Slashdot Mirror

An anonymous reader writes with a link to this "detailed and fascinating interview with Douglas Hofstadter (of Gödel Escher Bach fame) about his latest book, science fiction, Kurzweil's singularity and more ... Apparently this leading cognitive researcher wouldn't want to live in a world with AI, since 'Such a world would be too alien for me. I prefer living in a world where computers are still very very stupid.' He also wouldn't want to be around if Kurzweil's ideas come to pass, since he thinks 'it certainly would spell the end of human life.'"

Tal Cohen writes: "It is said that one of the most important skills a physicist needs is the ability to quickly make "back-of-the-envelope" calculations. For example, Jan Wolitzky (in Jon Bently's "Programming Pearls") tells about Enrico Fermi, Robert Oppenheimer, and the other Manhattan Project brass who were behind a low blast wall awaiting the detonation of the first nuclear device from a few thousand yards away. Fermi was tearing up sheets of paper into little pieces, which he tossed into the air when he saw the flash. After the shock wave passed, he paced off the distance traveled by the paper shreds, performed a quick "back-of-the-envelope" calculation, and arrived at a figure for the explosive yield of the bomb, which was confirmed much later by expensive monitoring equipment." Read on to find out what this has to do with the unusual characteristics of Earth, and how they could influence our search for life elsewhere in the universe. Rare Earth: Why Complex Life is Uncommon in the Universe author Peter D. Ward, Donald Brownlee pages 368 publisher Copernicus rating 7 reviewer Tal Cohen ISBN 0387987010 summary Maybe we are alone, after all.

But expensive monitoring equipment which can confirm the calculation does not always exist, and hence in some fields, our entire knowledge is based on back-of-the-envelope calculations and rough estimates.

Take, for example, the following question: "How many intelligent civilizations, capable of radio communications, currently exist in the Milky Way galaxy?". The worthwhileness of search projects (such as SETI) is closely related to the answer to this question. The number of positively known civilizations is exactly one: the human civilization. And yet, many scientists believe, or at least believed until recently, that the actual number is far, far higher.

This belief was based on various estimates, such as the calculation proposed by Frank Drake, now known as "The Drake Equation." This equation was popularized in Carl Sagan's remarkable TV series, "Cosmos". Sagan himself believed the calculation's result, and was one of the founders of SETI.

Drake's equation is easy to understand. Take the number of stars in the galaxy (about 200 to 300 billion, based on generally accepted estimates), and multiply it by: the percentage of stars that are similar to our Sun in the energy output and stability; the percentage of stars that have planets (since not every star has any); the percentage of planets orbiting their star in a proper distance (so they could hold liquid water, a necessity for maintaining life); the percentage of planets with liquid water on which life actually evolved; and finally, the percentage of life-bearing planets in which intelligent civilizations (i.e., those that can communicate by radio) eventually came to be. All in all, there are five or six factors in this product.

(Note: In my own copy of the book (2nd impression), page 267 states that "a good estimate for the number of stars in our galaxy [is] between 200 and 300 million" - one letter misspelled, and wrong by three orders of magnitude. I do hope the authors' actual calculations were based on the correct value.)

But what values should be used for the various percentages? Drake (and Sagan) chose what they considered to be a conservative approach, and estimated that only about 1 in 10 stars has any planets; only 1 in 10 planets is in the proper orbit, and so forth. Despite the conservative approach, the results were encouraging, indicating that there are thousands of intelligent civilizations in the Milky Way, and probably millions of them in the whole universe. Thus they concluded that there is intelligent life out there, in all likelihood; now we only have to look for it.

In their book Rare Earth, published by Copernicus Press in 2000, Peter Ward and Donald Brownlee point at Drake's (and other physicists') mistakes in a long and depressing discussion, a discussion that took the wind out of more than one SF author's sail.

The book presents what the authors call "the rare Earth hypothesis": simple (bacterial) life is very common in the universe; complex life (multi-cellular life forms, or animals -- let alone intelligent life) is very rare. The first part of the hypothesis is easy to understand, and few scientists will argue with it: indications of simple life were already discovered on rocks originating on Mars, and even here on Earth in conditions that were, until recently, considered completely hostile to life (such as temperatures higher than 100 degrees Celsius, in which 'extremophile' bacteria were found to exist). The second part is the interesting one, and it suggests that the existence of simple life does not necessarily lead to the evolutionary development of complex life, for any number of reasons.

Drake's mistake was basically in the assumption that all it takes for a planet to develop life is being in the proper distance from a proper star. The truth, Ward and Brownlee suggest, is that we have to look at each and every attribute of Earth, and re-estimate its importance for supporting life. Drake's equation is a statistical calculation, but with no other example for life, we're doing statistics with N=1.

Well then, what are the special attributes of Earth that we have to take into account when attempting to run this calculation?

• Proper distance from the star. If a planet orbits its sun too closely or too far away, liquid water would not exist. There isn't much margin for error here: a change of 5 to 15 percent in Earth's distance from the Sun would lead to the freezing, or boiling, of all water on Earth.
• Proper distance from the center of the galaxy. The density of stars near the center of the galaxy is so high, that the amount of cosmic radiation in that area would prevent the development of life.
• A star of a proper mass. A too-massive star would emit too much ultra-violet energy, preventing the development of life. A star that is too small would require the planet to be closer to it (in order to maintain liquid water). But such a close distance would result in tidal locking (where one face of the planet constantly faces the star, and the other always remains dark -- as with the moon in its orbit around Earth). In this case one side becomes too hot, the other too cold, and the planet's atmosphere escapes.
• A proper mass. A planet that is too small will not be able to maintain any atmosphere. A planet that is too massive would attract a larger number of asteroids, increasing the chances of life-destroying cataclysms.
• Oceans. The ability to maintain liquid water does not automatically imply that there will be any on the planet's surface. It looks like Earth acquired its own water from asteroids made of ice that crashed here billions of years ago. On the other hand, too much water (i.e., a planet with little or no land) will lead to an unstable atmosphere, unfit for maintaining life.
• A constant energy output from the star. If the star's energy output suddenly decreases, even for a relatively short while, all the water on the planet would freeze. This situation is irreversible, since when the star resumes its normal energy output, the planet's now-white surface will reflect most of this energy, and the ice will never melt. Conversely, if the stars energy output increases for a short while, all the oceans will evaporate and the result would be an irreversible greenhouse-effect, preventing the oceans from reforming.
• Successful evolution. Even if all of these conditions hold, and simple life evolves (which probably happens even if some of these conditions aren't met), this still does not imply that the result is animal (multi-cellular) life. The evolution of life on Earth included some surprising leaps; two worth mentioning are the move from simple, single-cellular life to cells which contain internal organs, and the appearance of calcium-based skeletons. It appears like the first of these leaps took more time than the evolution from complex single-celled life to full-blown humans.
• Avoiding disasters. Any number of disasters can lead to the complete extinction of all life on a planet. This include the supernova of a nearby star; a massive asteroid impact (like the one that probably caused the extinction of dinosaurs, and 70% of all other life-forms at the time); drastic changes of climate; and so on.

There are also a few attributes that seem, at first, to be completely unrelated to life and not required for its development. Ward and Brownlee argue strongly for the importance of the following attributes:

• The existence of a Jupiter-like planet in the system. Apparently, Jupiter's large mass attracted many of the asteroids that would have otherwise hit Earth. Could life evolve in a system with no Jovian planet? On the other hand, too many Jovian planets, or one that is too large, could lead to a non-stable solar system, sending the smaller planets into the central sun or ejecting them into the cold of space.
• The existence of a large, nearby moon. Luna, Earth's moon, is atypically large and close. Both of Mars's moons, for example, are minor rocks by comparison. What does this have to do with life? Well, it turns out that Luna kept (and still keeps) Earth's tilt stable. Without Luna, the tilt would have changed drastically over time, and no stable climate could exist. If the tilt would have stabilized on a too-large or too-small value, the results could also be disastrous; Earth's tilt is "just right."
• Plate tectonics. Surprisingly enough, it seems like plate tectonics are required for maintaining a stable atmosphere. Plate tectonics play an important role in a complex feedback system (explained in detail in the book) that prevents too many greenhouse gases from existing in the atmosphere. No other planet (except maybe for Jupiter's moon Europa) is known to have plate tectonics. Is this a rare phenomenon, but required for life?

The bottom line is that many additional factors must be added to Drake's equation. One must keep in mind that as any term in such an equation approaches zero, so too does the final product. For most terms, we have no way of reliably estimating their true value, but it seems like at least some of these values are extremely low.

Two important things should be noted about this book. First, about what it does not contain: although I am sure many people will see the Rare Earth Hypothesis as another proof for the existence of a god, this notion of a proof is completely unrelated to the authors' ideas. The hypothesis claims that the conditions for creating complex life are rare; but we know for a fact that at least in one case, all the required conditions were met. Additionally, anyone who insists on taking the ideas of this book as a proof for god's existence will also have to accept the authors' prepositions about the age of the universe, the age of planet Earth, and more importantly, the theory of evolution.

Second, about what the book does contain: the book discusses at length all the issues I've listed above, and more. The problem is that sometimes one gets the feeling that these issues are discussed in too much detail, and the authors tend to repeat themselves, or to delve too deep into some of the less-important aspects of their theory. This is certainly not your common popular-science book; it relies on very up-to-date research results (including some results that were not even published when the book went to press). The writing gets technical on many points in astrophysics, biology, chemistry, and geology (as well as the new field of astrobiology, of course). Over 25 pages of bibliography and references are included.

The theory's weakest point, however, is obvious. The authors admit (after 281 pages of discussion) that their base assumption was that every complex life-form would be similar in many ways to life on Earth: "We assume in this book that animal life will be somehow Earth-like. We take the perhaps jingoistic stance that Earth-life is every-life, that lessons from Earth are not only guides but also rules. We assume that DNA is the only way, rather than only one way" (p. 282).

For me, reading this book was a fascinating and awe-inspiring experience. The most important conclusion (apart from SETI being a huge waste of resources) is an unavoidable cliché, which the authors avoided presenting directly, even though it stares into the reader's face from every page and each paragraph: What we have here is rare, maybe even unique. We should try a little harder to make sure it survives.

Post Scriptum: A news item in the November/December 2001 issue of the Skeptical Inquirer (Vol. 25, No. 6) states that "David Darling, an astronomer who is a critic of the Rare Earth hypothesis, has revealed that one of the strongest influences on the authors, a young [...] astronomer who they acknowledge in their preface 'changed many of our views about planets and habitable zones', has a hidden, Earth-is-unique agenda motivated by strong 'intelligent design' religious views." That astronomer, Guillermo Gonzalez, published several articles in Connections, a quarterly newsletter published by Reasons to Believe, Inc. In one of these articles, co-authored with the creationist scientist Hugh Ross, Gonzalez writes: "The fact that the Sun's location is fine-tuned to permit the possibility of life [...] powerfully suggests divine design."

Darling published these findings, along with a detailed point-by-point scientific critique of the Rare Earth hypothesis, in his book Life Everywhere: The Maverick Science of Astrobiology . Skeptical Inquirer quotes Darling as saying, "What matters is not whether there's anything unusual about the Earth; there's going to be something idiosyncratic about every planet in space. What matters is whether any of Earth's circumstances are not only unusual but also essential for complex life. So far we've seen nothing to suggest there is."

For more about this book, please see this page. For additional book reviews, please visit Tal's bookshelf. You can purchase Rare Earth from bn.com. Want to see your own review here? Just read the book review guidelines, then use Slashdot's handy submission form.

Tal Cohen writes: "It is said that one of the most important skills a physicist needs is the ability to quickly make "back-of-the-envelope" calculations. For example, Jan Wolitzky (in Jon Bently's "Programming Pearls") tells about Enrico Fermi, Robert Oppenheimer, and the other Manhattan Project brass who were behind a low blast wall awaiting the detonation of the first nuclear device from a few thousand yards away. Fermi was tearing up sheets of paper into little pieces, which he tossed into the air when he saw the flash. After the shock wave passed, he paced off the distance traveled by the paper shreds, performed a quick "back-of-the-envelope" calculation, and arrived at a figure for the explosive yield of the bomb, which was confirmed much later by expensive monitoring equipment." Read on to find out what this has to do with the unusual characteristics of Earth, and how they could influence our search for life elsewhere in the universe. Rare Earth: Why Complex Life is Uncommon in the Universe author Peter D. Ward, Donald Brownlee pages 368 publisher Copernicus rating 7 reviewer Tal Cohen ISBN 0387987010 summary Maybe we are alone, after all.

But expensive monitoring equipment which can confirm the calculation does not always exist, and hence in some fields, our entire knowledge is based on back-of-the-envelope calculations and rough estimates.

Take, for example, the following question: "How many intelligent civilizations, capable of radio communications, currently exist in the Milky Way galaxy?". The worthwhileness of search projects (such as SETI) is closely related to the answer to this question. The number of positively known civilizations is exactly one: the human civilization. And yet, many scientists believe, or at least believed until recently, that the actual number is far, far higher.

This belief was based on various estimates, such as the calculation proposed by Frank Drake, now known as "The Drake Equation." This equation was popularized in Carl Sagan's remarkable TV series, "Cosmos". Sagan himself believed the calculation's result, and was one of the founders of SETI.

Drake's equation is easy to understand. Take the number of stars in the galaxy (about 200 to 300 billion, based on generally accepted estimates), and multiply it by: the percentage of stars that are similar to our Sun in the energy output and stability; the percentage of stars that have planets (since not every star has any); the percentage of planets orbiting their star in a proper distance (so they could hold liquid water, a necessity for maintaining life); the percentage of planets with liquid water on which life actually evolved; and finally, the percentage of life-bearing planets in which intelligent civilizations (i.e., those that can communicate by radio) eventually came to be. All in all, there are five or six factors in this product.

(Note: In my own copy of the book (2nd impression), page 267 states that "a good estimate for the number of stars in our galaxy [is] between 200 and 300 million" - one letter misspelled, and wrong by three orders of magnitude. I do hope the authors' actual calculations were based on the correct value.)

But what values should be used for the various percentages? Drake (and Sagan) chose what they considered to be a conservative approach, and estimated that only about 1 in 10 stars has any planets; only 1 in 10 planets is in the proper orbit, and so forth. Despite the conservative approach, the results were encouraging, indicating that there are thousands of intelligent civilizations in the Milky Way, and probably millions of them in the whole universe. Thus they concluded that there is intelligent life out there, in all likelihood; now we only have to look for it.

In their book Rare Earth, published by Copernicus Press in 2000, Peter Ward and Donald Brownlee point at Drake's (and other physicists') mistakes in a long and depressing discussion, a discussion that took the wind out of more than one SF author's sail.

The book presents what the authors call "the rare Earth hypothesis": simple (bacterial) life is very common in the universe; complex life (multi-cellular life forms, or animals -- let alone intelligent life) is very rare. The first part of the hypothesis is easy to understand, and few scientists will argue with it: indications of simple life were already discovered on rocks originating on Mars, and even here on Earth in conditions that were, until recently, considered completely hostile to life (such as temperatures higher than 100 degrees Celsius, in which 'extremophile' bacteria were found to exist). The second part is the interesting one, and it suggests that the existence of simple life does not necessarily lead to the evolutionary development of complex life, for any number of reasons.

Drake's mistake was basically in the assumption that all it takes for a planet to develop life is being in the proper distance from a proper star. The truth, Ward and Brownlee suggest, is that we have to look at each and every attribute of Earth, and re-estimate its importance for supporting life. Drake's equation is a statistical calculation, but with no other example for life, we're doing statistics with N=1.

Well then, what are the special attributes of Earth that we have to take into account when attempting to run this calculation?

• Proper distance from the star. If a planet orbits its sun too closely or too far away, liquid water would not exist. There isn't much margin for error here: a change of 5 to 15 percent in Earth's distance from the Sun would lead to the freezing, or boiling, of all water on Earth.
• Proper distance from the center of the galaxy. The density of stars near the center of the galaxy is so high, that the amount of cosmic radiation in that area would prevent the development of life.
• A star of a proper mass. A too-massive star would emit too much ultra-violet energy, preventing the development of life. A star that is too small would require the planet to be closer to it (in order to maintain liquid water). But such a close distance would result in tidal locking (where one face of the planet constantly faces the star, and the other always remains dark -- as with the moon in its orbit around Earth). In this case one side becomes too hot, the other too cold, and the planet's atmosphere escapes.
• A proper mass. A planet that is too small will not be able to maintain any atmosphere. A planet that is too massive would attract a larger number of asteroids, increasing the chances of life-destroying cataclysms.
• Oceans. The ability to maintain liquid water does not automatically imply that there will be any on the planet's surface. It looks like Earth acquired its own water from asteroids made of ice that crashed here billions of years ago. On the other hand, too much water (i.e., a planet with little or no land) will lead to an unstable atmosphere, unfit for maintaining life.
• A constant energy output from the star. If the star's energy output suddenly decreases, even for a relatively short while, all the water on the planet would freeze. This situation is irreversible, since when the star resumes its normal energy output, the planet's now-white surface will reflect most of this energy, and the ice will never melt. Conversely, if the stars energy output increases for a short while, all the oceans will evaporate and the result would be an irreversible greenhouse-effect, preventing the oceans from reforming.
• Successful evolution. Even if all of these conditions hold, and simple life evolves (which probably happens even if some of these conditions aren't met), this still does not imply that the result is animal (multi-cellular) life. The evolution of life on Earth included some surprising leaps; two worth mentioning are the move from simple, single-cellular life to cells which contain internal organs, and the appearance of calcium-based skeletons. It appears like the first of these leaps took more time than the evolution from complex single-celled life to full-blown humans.
• Avoiding disasters. Any number of disasters can lead to the complete extinction of all life on a planet. This include the supernova of a nearby star; a massive asteroid impact (like the one that probably caused the extinction of dinosaurs, and 70% of all other life-forms at the time); drastic changes of climate; and so on.

There are also a few attributes that seem, at first, to be completely unrelated to life and not required for its development. Ward and Brownlee argue strongly for the importance of the following attributes:

• The existence of a Jupiter-like planet in the system. Apparently, Jupiter's large mass attracted many of the asteroids that would have otherwise hit Earth. Could life evolve in a system with no Jovian planet? On the other hand, too many Jovian planets, or one that is too large, could lead to a non-stable solar system, sending the smaller planets into the central sun or ejecting them into the cold of space.
• The existence of a large, nearby moon. Luna, Earth's moon, is atypically large and close. Both of Mars's moons, for example, are minor rocks by comparison. What does this have to do with life? Well, it turns out that Luna kept (and still keeps) Earth's tilt stable. Without Luna, the tilt would have changed drastically over time, and no stable climate could exist. If the tilt would have stabilized on a too-large or too-small value, the results could also be disastrous; Earth's tilt is "just right."
• Plate tectonics. Surprisingly enough, it seems like plate tectonics are required for maintaining a stable atmosphere. Plate tectonics play an important role in a complex feedback system (explained in detail in the book) that prevents too many greenhouse gases from existing in the atmosphere. No other planet (except maybe for Jupiter's moon Europa) is known to have plate tectonics. Is this a rare phenomenon, but required for life?

The bottom line is that many additional factors must be added to Drake's equation. One must keep in mind that as any term in such an equation approaches zero, so too does the final product. For most terms, we have no way of reliably estimating their true value, but it seems like at least some of these values are extremely low.

Two important things should be noted about this book. First, about what it does not contain: although I am sure many people will see the Rare Earth Hypothesis as another proof for the existence of a god, this notion of a proof is completely unrelated to the authors' ideas. The hypothesis claims that the conditions for creating complex life are rare; but we know for a fact that at least in one case, all the required conditions were met. Additionally, anyone who insists on taking the ideas of this book as a proof for god's existence will also have to accept the authors' prepositions about the age of the universe, the age of planet Earth, and more importantly, the theory of evolution.

Second, about what the book does contain: the book discusses at length all the issues I've listed above, and more. The problem is that sometimes one gets the feeling that these issues are discussed in too much detail, and the authors tend to repeat themselves, or to delve too deep into some of the less-important aspects of their theory. This is certainly not your common popular-science book; it relies on very up-to-date research results (including some results that were not even published when the book went to press). The writing gets technical on many points in astrophysics, biology, chemistry, and geology (as well as the new field of astrobiology, of course). Over 25 pages of bibliography and references are included.

The theory's weakest point, however, is obvious. The authors admit (after 281 pages of discussion) that their base assumption was that every complex life-form would be similar in many ways to life on Earth: "We assume in this book that animal life will be somehow Earth-like. We take the perhaps jingoistic stance that Earth-life is every-life, that lessons from Earth are not only guides but also rules. We assume that DNA is the only way, rather than only one way" (p. 282).

For me, reading this book was a fascinating and awe-inspiring experience. The most important conclusion (apart from SETI being a huge waste of resources) is an unavoidable cliché, which the authors avoided presenting directly, even though it stares into the reader's face from every page and each paragraph: What we have here is rare, maybe even unique. We should try a little harder to make sure it survives.

Post Scriptum: A news item in the November/December 2001 issue of the Skeptical Inquirer (Vol. 25, No. 6) states that "David Darling, an astronomer who is a critic of the Rare Earth hypothesis, has revealed that one of the strongest influences on the authors, a young [...] astronomer who they acknowledge in their preface 'changed many of our views about planets and habitable zones', has a hidden, Earth-is-unique agenda motivated by strong 'intelligent design' religious views." That astronomer, Guillermo Gonzalez, published several articles in Connections, a quarterly newsletter published by Reasons to Believe, Inc. In one of these articles, co-authored with the creationist scientist Hugh Ross, Gonzalez writes: "The fact that the Sun's location is fine-tuned to permit the possibility of life [...] powerfully suggests divine design."

Darling published these findings, along with a detailed point-by-point scientific critique of the Rare Earth hypothesis, in his book Life Everywhere: The Maverick Science of Astrobiology . Skeptical Inquirer quotes Darling as saying, "What matters is not whether there's anything unusual about the Earth; there's going to be something idiosyncratic about every planet in space. What matters is whether any of Earth's circumstances are not only unusual but also essential for complex life. So far we've seen nothing to suggest there is."

For more about this book, please see this page. For additional book reviews, please visit Tal's bookshelf. You can purchase Rare Earth from bn.com. Want to see your own review here? Just read the book review guidelines, then use Slashdot's handy submission form.

Tal Cohen writes: "It is said that one of the most important skills a physicist needs is the ability to quickly make "back-of-the-envelope" calculations. For example, Jan Wolitzky (in Jon Bently's "Programming Pearls") tells about Enrico Fermi, Robert Oppenheimer, and the other Manhattan Project brass who were behind a low blast wall awaiting the detonation of the first nuclear device from a few thousand yards away. Fermi was tearing up sheets of paper into little pieces, which he tossed into the air when he saw the flash. After the shock wave passed, he paced off the distance traveled by the paper shreds, performed a quick "back-of-the-envelope" calculation, and arrived at a figure for the explosive yield of the bomb, which was confirmed much later by expensive monitoring equipment." Read on to find out what this has to do with the unusual characteristics of Earth, and how they could influence our search for life elsewhere in the universe. Rare Earth: Why Complex Life is Uncommon in the Universe author Peter D. Ward, Donald Brownlee pages 368 publisher Copernicus rating 7 reviewer Tal Cohen ISBN 0387987010 summary Maybe we are alone, after all.

But expensive monitoring equipment which can confirm the calculation does not always exist, and hence in some fields, our entire knowledge is based on back-of-the-envelope calculations and rough estimates.

Take, for example, the following question: "How many intelligent civilizations, capable of radio communications, currently exist in the Milky Way galaxy?". The worthwhileness of search projects (such as SETI) is closely related to the answer to this question. The number of positively known civilizations is exactly one: the human civilization. And yet, many scientists believe, or at least believed until recently, that the actual number is far, far higher.

This belief was based on various estimates, such as the calculation proposed by Frank Drake, now known as "The Drake Equation." This equation was popularized in Carl Sagan's remarkable TV series, "Cosmos". Sagan himself believed the calculation's result, and was one of the founders of SETI.

Drake's equation is easy to understand. Take the number of stars in the galaxy (about 200 to 300 billion, based on generally accepted estimates), and multiply it by: the percentage of stars that are similar to our Sun in the energy output and stability; the percentage of stars that have planets (since not every star has any); the percentage of planets orbiting their star in a proper distance (so they could hold liquid water, a necessity for maintaining life); the percentage of planets with liquid water on which life actually evolved; and finally, the percentage of life-bearing planets in which intelligent civilizations (i.e., those that can communicate by radio) eventually came to be. All in all, there are five or six factors in this product.

(Note: In my own copy of the book (2nd impression), page 267 states that "a good estimate for the number of stars in our galaxy [is] between 200 and 300 million" - one letter misspelled, and wrong by three orders of magnitude. I do hope the authors' actual calculations were based on the correct value.)

But what values should be used for the various percentages? Drake (and Sagan) chose what they considered to be a conservative approach, and estimated that only about 1 in 10 stars has any planets; only 1 in 10 planets is in the proper orbit, and so forth. Despite the conservative approach, the results were encouraging, indicating that there are thousands of intelligent civilizations in the Milky Way, and probably millions of them in the whole universe. Thus they concluded that there is intelligent life out there, in all likelihood; now we only have to look for it.

In their book Rare Earth, published by Copernicus Press in 2000, Peter Ward and Donald Brownlee point at Drake's (and other physicists') mistakes in a long and depressing discussion, a discussion that took the wind out of more than one SF author's sail.

The book presents what the authors call "the rare Earth hypothesis": simple (bacterial) life is very common in the universe; complex life (multi-cellular life forms, or animals -- let alone intelligent life) is very rare. The first part of the hypothesis is easy to understand, and few scientists will argue with it: indications of simple life were already discovered on rocks originating on Mars, and even here on Earth in conditions that were, until recently, considered completely hostile to life (such as temperatures higher than 100 degrees Celsius, in which 'extremophile' bacteria were found to exist). The second part is the interesting one, and it suggests that the existence of simple life does not necessarily lead to the evolutionary development of complex life, for any number of reasons.

Drake's mistake was basically in the assumption that all it takes for a planet to develop life is being in the proper distance from a proper star. The truth, Ward and Brownlee suggest, is that we have to look at each and every attribute of Earth, and re-estimate its importance for supporting life. Drake's equation is a statistical calculation, but with no other example for life, we're doing statistics with N=1.

Well then, what are the special attributes of Earth that we have to take into account when attempting to run this calculation?

• Proper distance from the star. If a planet orbits its sun too closely or too far away, liquid water would not exist. There isn't much margin for error here: a change of 5 to 15 percent in Earth's distance from the Sun would lead to the freezing, or boiling, of all water on Earth.
• Proper distance from the center of the galaxy. The density of stars near the center of the galaxy is so high, that the amount of cosmic radiation in that area would prevent the development of life.
• A star of a proper mass. A too-massive star would emit too much ultra-violet energy, preventing the development of life. A star that is too small would require the planet to be closer to it (in order to maintain liquid water). But such a close distance would result in tidal locking (where one face of the planet constantly faces the star, and the other always remains dark -- as with the moon in its orbit around Earth). In this case one side becomes too hot, the other too cold, and the planet's atmosphere escapes.
• A proper mass. A planet that is too small will not be able to maintain any atmosphere. A planet that is too massive would attract a larger number of asteroids, increasing the chances of life-destroying cataclysms.
• Oceans. The ability to maintain liquid water does not automatically imply that there will be any on the planet's surface. It looks like Earth acquired its own water from asteroids made of ice that crashed here billions of years ago. On the other hand, too much water (i.e., a planet with little or no land) will lead to an unstable atmosphere, unfit for maintaining life.
• A constant energy output from the star. If the star's energy output suddenly decreases, even for a relatively short while, all the water on the planet would freeze. This situation is irreversible, since when the star resumes its normal energy output, the planet's now-white surface will reflect most of this energy, and the ice will never melt. Conversely, if the stars energy output increases for a short while, all the oceans will evaporate and the result would be an irreversible greenhouse-effect, preventing the oceans from reforming.
• Successful evolution. Even if all of these conditions hold, and simple life evolves (which probably happens even if some of these conditions aren't met), this still does not imply that the result is animal (multi-cellular) life. The evolution of life on Earth included some surprising leaps; two worth mentioning are the move from simple, single-cellular life to cells which contain internal organs, and the appearance of calcium-based skeletons. It appears like the first of these leaps took more time than the evolution from complex single-celled life to full-blown humans.
• Avoiding disasters. Any number of disasters can lead to the complete extinction of all life on a planet. This include the supernova of a nearby star; a massive asteroid impact (like the one that probably caused the extinction of dinosaurs, and 70% of all other life-forms at the time); drastic changes of climate; and so on.

There are also a few attributes that seem, at first, to be completely unrelated to life and not required for its development. Ward and Brownlee argue strongly for the importance of the following attributes:

• The existence of a Jupiter-like planet in the system. Apparently, Jupiter's large mass attracted many of the asteroids that would have otherwise hit Earth. Could life evolve in a system with no Jovian planet? On the other hand, too many Jovian planets, or one that is too large, could lead to a non-stable solar system, sending the smaller planets into the central sun or ejecting them into the cold of space.
• The existence of a large, nearby moon. Luna, Earth's moon, is atypically large and close. Both of Mars's moons, for example, are minor rocks by comparison. What does this have to do with life? Well, it turns out that Luna kept (and still keeps) Earth's tilt stable. Without Luna, the tilt would have changed drastically over time, and no stable climate could exist. If the tilt would have stabilized on a too-large or too-small value, the results could also be disastrous; Earth's tilt is "just right."
• Plate tectonics. Surprisingly enough, it seems like plate tectonics are required for maintaining a stable atmosphere. Plate tectonics play an important role in a complex feedback system (explained in detail in the book) that prevents too many greenhouse gases from existing in the atmosphere. No other planet (except maybe for Jupiter's moon Europa) is known to have plate tectonics. Is this a rare phenomenon, but required for life?

The bottom line is that many additional factors must be added to Drake's equation. One must keep in mind that as any term in such an equation approaches zero, so too does the final product. For most terms, we have no way of reliably estimating their true value, but it seems like at least some of these values are extremely low.

Two important things should be noted about this book. First, about what it does not contain: although I am sure many people will see the Rare Earth Hypothesis as another proof for the existence of a god, this notion of a proof is completely unrelated to the authors' ideas. The hypothesis claims that the conditions for creating complex life are rare; but we know for a fact that at least in one case, all the required conditions were met. Additionally, anyone who insists on taking the ideas of this book as a proof for god's existence will also have to accept the authors' prepositions about the age of the universe, the age of planet Earth, and more importantly, the theory of evolution.

Second, about what the book does contain: the book discusses at length all the issues I've listed above, and more. The problem is that sometimes one gets the feeling that these issues are discussed in too much detail, and the authors tend to repeat themselves, or to delve too deep into some of the less-important aspects of their theory. This is certainly not your common popular-science book; it relies on very up-to-date research results (including some results that were not even published when the book went to press). The writing gets technical on many points in astrophysics, biology, chemistry, and geology (as well as the new field of astrobiology, of course). Over 25 pages of bibliography and references are included.

The theory's weakest point, however, is obvious. The authors admit (after 281 pages of discussion) that their base assumption was that every complex life-form would be similar in many ways to life on Earth: "We assume in this book that animal life will be somehow Earth-like. We take the perhaps jingoistic stance that Earth-life is every-life, that lessons from Earth are not only guides but also rules. We assume that DNA is the only way, rather than only one way" (p. 282).

For me, reading this book was a fascinating and awe-inspiring experience. The most important conclusion (apart from SETI being a huge waste of resources) is an unavoidable cliché, which the authors avoided presenting directly, even though it stares into the reader's face from every page and each paragraph: What we have here is rare, maybe even unique. We should try a little harder to make sure it survives.

Post Scriptum: A news item in the November/December 2001 issue of the Skeptical Inquirer (Vol. 25, No. 6) states that "David Darling, an astronomer who is a critic of the Rare Earth hypothesis, has revealed that one of the strongest influences on the authors, a young [...] astronomer who they acknowledge in their preface 'changed many of our views about planets and habitable zones', has a hidden, Earth-is-unique agenda motivated by strong 'intelligent design' religious views." That astronomer, Guillermo Gonzalez, published several articles in Connections, a quarterly newsletter published by Reasons to Believe, Inc. In one of these articles, co-authored with the creationist scientist Hugh Ross, Gonzalez writes: "The fact that the Sun's location is fine-tuned to permit the possibility of life [...] powerfully suggests divine design."

Darling published these findings, along with a detailed point-by-point scientific critique of the Rare Earth hypothesis, in his book Life Everywhere: The Maverick Science of Astrobiology . Skeptical Inquirer quotes Darling as saying, "What matters is not whether there's anything unusual about the Earth; there's going to be something idiosyncratic about every planet in space. What matters is whether any of Earth's circumstances are not only unusual but also essential for complex life. So far we've seen nothing to suggest there is."

For more about this book, please see this page. For additional book reviews, please visit Tal's bookshelf. You can purchase Rare Earth from bn.com. Want to see your own review here? Just read the book review guidelines, then use Slashdot's handy submission form.

Tal Cohen writes "Borland Kylix 2 is now available. Most new features are geared at Enterprise-level developers; the Open edition is still available for free download. The CLX (cross-platform component library) is covered under both GNU and Borland's license." The new features list is interesting - a fair number of buzzwords, but it also looks like they are supporting a lot of the new stuff. The white papers have some interesting topics - including gcc vs. Kylix.

Tal Cohen, one of our best book reviewers thought that the Slashdot audience would appreciate Pattern Hatching: Design Patterns Applied, a book written by John Vlissides. This book is not one of the many new pattern catalogs, this book shows how patterns are applied in real life -- and also includes some interesting guidelines for would-be pattern writers. Pattern Hatching: Design Patterns Applied author John Vlissides pages 172 publisher Addison-Wesley, 06/1998 rating 7/10 reviewer Tal Cohen ISBN 0-201-43293-5 summary Not one of the many new pattern catalogs, this book shows how patterns are applied in real life -- and also includes some interesting guidelines for would-be patternwriters. Along with all the hoopla surrounding patterns these days comes more than a little confusion, consternation, and misinformation. This is partly a reflection of how new the field is to mainstream software developers even though it's not, strictly speaking, a new field. It's a fast-moving field too, creating vacuums of facts. And yes, we pattern proponents deserve some of the blame for not educating people as thoroughly as we'd like, though not for lack of trying.

John Vlissides, a member of the "Gang of Four" -- the authors of Design Patterns, presents another book on the subject. In part, this book presents some important aspects in using patterns; hence the subtitle "Design Patterns Applied" is right on the spot. Vlissides shows when certain patterns are used in real life, and even quotes a lot of e-mail from other users, showing patten advantages and, notably, weaknesses. As Vlissides states, "This book conveys something very important that's missing in the more academic and published Design Patterns book -- that patterns are the result of real, working programmers who don't get everything right the first time, and who struggle with the pragmatics of recurring design practices" (page x). Herein lies the book's greatest strength. Another part is aimed for pattern writers, rather than users. Sadly, these is no clear separation between these two aspects of the book.

The book is basically a collection of Vlissides's columns in C++ Report, and this is arguably the book's weakest point: if you're not intimately familiar with the little details of C++, you'll miss much of the action. This is sad, because the original Design Patterns book was careful to present patterns in a relatively language-independent manner, both in C++ and in Smalltalk. Here, the view is strongly biased towards C++, in ways that sometimes would annoy (or amuse) users of other languages, such as Smalltalk or Java.

Consider, for exmaple, Chapter 3: "Themes and Variations". A large portion of the chapter deals with the de-allocation problem of Singleton objects. Any programmer who uses a garbage-collecting language will be simply amused by the entire hoopla. The only conclusion from the entire discussion, one that the author himself admits (p. 69 and elsewhere), is that the lack of garbage collection greatly increases design complexity, in addition to program complexity. A design that had the potential of being elegant turns out into an ugly monster by the need to manually manage memory deallocation. Not to mention the suggested use of "delete this" (p. 41). The author is "not sure why, but [...] people wince at delete this". Hint, John: objects sometimes reside on the stack. In which case delete this can have very... interesting consequences. (True, in the context of a Singleton, where allocation is controlled and cannot occur on stack, this specific problem is not present, and yet "delete this" is such an evil construct, with such horrible possible results, that I'd rather avoid it even in such controlled cases.)

And sadly, the entire discussion on the use of Singletons ignores what I've come to conlude is the pattern's worst, and most common, misuse: Singletons, in my experience, are a tempting (and in practically all cases wrong) replacement for global variables. A designer that finds a need for a global variable simply replaces it with a Singleton, and pronounces that not only he's not using globals, but rather he's using a known pattern, which must mean his design is good.

Chapter 2 is a tour-de-force of using "classical" patterns, those presented in the original Design Patterns book. The examples look a little forced, and life too simple (every problem has a corresponding pattern that fits it like a glove), and yet it is a most educating read. For one relatively simple problem, the author comes up with an elegant solution that uses no less than six patterns (Proxy, Composite, Template Method, Visitor, Mediator and Singleton) -- and suggests an enhancement using a seventh one (Observer). This discussion alone could be worth the effort of reading the book, as it examplifies the correct and practical use of patterns in real life. The end of the chapter presents a very nice kind of diagram, invented by Erich Gamma, which could be very useful indeed. This "pattern:role annotation", as Gamma calls it, allows people who are sufficiently fluent in the pattern language of design to immediately grasp the role of different objects, even in a large design.

Chapters 4 and 5 are aimed mainly for pattern developers, though this is not clear when one begins to read them. It includes an example of the Gang of Four's elaborate discussions about pattern design, with lots of quotes from e-mail messages, etc. This is interesting only to a certain extent. The discussion, basically, is about whether Multicast should be presented as a pattern in its own right, or as an adaptation of the Observer pattern. Most of the discussion seemed to be dealing with minute neuances, but the conclusion (the presentation of a whole new pattern, "Typed Message"), is a beautiful one.

The concluding chapter (5) is titled "Seven Habits of Effective Pattern Writers". The name says it all. Though some of the advice presented (e.g. number 5, "Presenting Effectively") are trivial, others (e.g. number 1, "Taking Time to Reflect") are very educating. (Don't be mislead by that simple title, "Taking Time to Reflect". Vlissides provides some real important tips under this seemingly obvious one.)

In conclusion, if you do a lot of object-oriented design, and use (or consider using) design patterns, reading this book can be a good use of your time; but unless you spend time on designing patterns, too, you might wish to simply skim the last two chapters.

Pick this book up at ThinkGeek.

For additional book reviews, please visit http://www.forum2.org/tal/books.

Tal Cohen, one of our best book reviewers thought that the Slashdot audience would appreciate Pattern Hatching: Design Patterns Applied, a book written by John Vlissides. This book is not one of the many new pattern catalogs, this book shows how patterns are applied in real life -- and also includes some interesting guidelines for would-be pattern writers. Pattern Hatching: Design Patterns Applied author John Vlissides pages 172 publisher Addison-Wesley, 06/1998 rating 7/10 reviewer Tal Cohen ISBN 0-201-43293-5 summary Not one of the many new pattern catalogs, this book shows how patterns are applied in real life -- and also includes some interesting guidelines for would-be patternwriters. Along with all the hoopla surrounding patterns these days comes more than a little confusion, consternation, and misinformation. This is partly a reflection of how new the field is to mainstream software developers even though it's not, strictly speaking, a new field. It's a fast-moving field too, creating vacuums of facts. And yes, we pattern proponents deserve some of the blame for not educating people as thoroughly as we'd like, though not for lack of trying.

John Vlissides, a member of the "Gang of Four" -- the authors of Design Patterns, presents another book on the subject. In part, this book presents some important aspects in using patterns; hence the subtitle "Design Patterns Applied" is right on the spot. Vlissides shows when certain patterns are used in real life, and even quotes a lot of e-mail from other users, showing patten advantages and, notably, weaknesses. As Vlissides states, "This book conveys something very important that's missing in the more academic and published Design Patterns book -- that patterns are the result of real, working programmers who don't get everything right the first time, and who struggle with the pragmatics of recurring design practices" (page x). Herein lies the book's greatest strength. Another part is aimed for pattern writers, rather than users. Sadly, these is no clear separation between these two aspects of the book.

The book is basically a collection of Vlissides's columns in C++ Report, and this is arguably the book's weakest point: if you're not intimately familiar with the little details of C++, you'll miss much of the action. This is sad, because the original Design Patterns book was careful to present patterns in a relatively language-independent manner, both in C++ and in Smalltalk. Here, the view is strongly biased towards C++, in ways that sometimes would annoy (or amuse) users of other languages, such as Smalltalk or Java.

Consider, for exmaple, Chapter 3: "Themes and Variations". A large portion of the chapter deals with the de-allocation problem of Singleton objects. Any programmer who uses a garbage-collecting language will be simply amused by the entire hoopla. The only conclusion from the entire discussion, one that the author himself admits (p. 69 and elsewhere), is that the lack of garbage collection greatly increases design complexity, in addition to program complexity. A design that had the potential of being elegant turns out into an ugly monster by the need to manually manage memory deallocation. Not to mention the suggested use of "delete this" (p. 41). The author is "not sure why, but [...] people wince at delete this". Hint, John: objects sometimes reside on the stack. In which case delete this can have very... interesting consequences. (True, in the context of a Singleton, where allocation is controlled and cannot occur on stack, this specific problem is not present, and yet "delete this" is such an evil construct, with such horrible possible results, that I'd rather avoid it even in such controlled cases.)

And sadly, the entire discussion on the use of Singletons ignores what I've come to conlude is the pattern's worst, and most common, misuse: Singletons, in my experience, are a tempting (and in practically all cases wrong) replacement for global variables. A designer that finds a need for a global variable simply replaces it with a Singleton, and pronounces that not only he's not using globals, but rather he's using a known pattern, which must mean his design is good.

Chapter 2 is a tour-de-force of using "classical" patterns, those presented in the original Design Patterns book. The examples look a little forced, and life too simple (every problem has a corresponding pattern that fits it like a glove), and yet it is a most educating read. For one relatively simple problem, the author comes up with an elegant solution that uses no less than six patterns (Proxy, Composite, Template Method, Visitor, Mediator and Singleton) -- and suggests an enhancement using a seventh one (Observer). This discussion alone could be worth the effort of reading the book, as it examplifies the correct and practical use of patterns in real life. The end of the chapter presents a very nice kind of diagram, invented by Erich Gamma, which could be very useful indeed. This "pattern:role annotation", as Gamma calls it, allows people who are sufficiently fluent in the pattern language of design to immediately grasp the role of different objects, even in a large design.

Chapters 4 and 5 are aimed mainly for pattern developers, though this is not clear when one begins to read them. It includes an example of the Gang of Four's elaborate discussions about pattern design, with lots of quotes from e-mail messages, etc. This is interesting only to a certain extent. The discussion, basically, is about whether Multicast should be presented as a pattern in its own right, or as an adaptation of the Observer pattern. Most of the discussion seemed to be dealing with minute neuances, but the conclusion (the presentation of a whole new pattern, "Typed Message"), is a beautiful one.

The concluding chapter (5) is titled "Seven Habits of Effective Pattern Writers". The name says it all. Though some of the advice presented (e.g. number 5, "Presenting Effectively") are trivial, others (e.g. number 1, "Taking Time to Reflect") are very educating. (Don't be mislead by that simple title, "Taking Time to Reflect". Vlissides provides some real important tips under this seemingly obvious one.)

In conclusion, if you do a lot of object-oriented design, and use (or consider using) design patterns, reading this book can be a good use of your time; but unless you spend time on designing patterns, too, you might wish to simply skim the last two chapters.

Pick this book up at ThinkGeek.

For additional book reviews, please visit http://www.forum2.org/tal/books.

Tal Cohen, one of our best book reviewers thought that the Slashdot audience would appreciate Pattern Hatching: Design Patterns Applied, a book written by John Vlissides. This book is not one of the many new pattern catalogs, this book shows how patterns are applied in real life -- and also includes some interesting guidelines for would-be pattern writers. Pattern Hatching: Design Patterns Applied author John Vlissides pages 172 publisher Addison-Wesley, 06/1998 rating 7/10 reviewer Tal Cohen ISBN 0-201-43293-5 summary Not one of the many new pattern catalogs, this book shows how patterns are applied in real life -- and also includes some interesting guidelines for would-be patternwriters. Along with all the hoopla surrounding patterns these days comes more than a little confusion, consternation, and misinformation. This is partly a reflection of how new the field is to mainstream software developers even though it's not, strictly speaking, a new field. It's a fast-moving field too, creating vacuums of facts. And yes, we pattern proponents deserve some of the blame for not educating people as thoroughly as we'd like, though not for lack of trying.

John Vlissides, a member of the "Gang of Four" -- the authors of Design Patterns, presents another book on the subject. In part, this book presents some important aspects in using patterns; hence the subtitle "Design Patterns Applied" is right on the spot. Vlissides shows when certain patterns are used in real life, and even quotes a lot of e-mail from other users, showing patten advantages and, notably, weaknesses. As Vlissides states, "This book conveys something very important that's missing in the more academic and published Design Patterns book -- that patterns are the result of real, working programmers who don't get everything right the first time, and who struggle with the pragmatics of recurring design practices" (page x). Herein lies the book's greatest strength. Another part is aimed for pattern writers, rather than users. Sadly, these is no clear separation between these two aspects of the book.

The book is basically a collection of Vlissides's columns in C++ Report, and this is arguably the book's weakest point: if you're not intimately familiar with the little details of C++, you'll miss much of the action. This is sad, because the original Design Patterns book was careful to present patterns in a relatively language-independent manner, both in C++ and in Smalltalk. Here, the view is strongly biased towards C++, in ways that sometimes would annoy (or amuse) users of other languages, such as Smalltalk or Java.

Consider, for exmaple, Chapter 3: "Themes and Variations". A large portion of the chapter deals with the de-allocation problem of Singleton objects. Any programmer who uses a garbage-collecting language will be simply amused by the entire hoopla. The only conclusion from the entire discussion, one that the author himself admits (p. 69 and elsewhere), is that the lack of garbage collection greatly increases design complexity, in addition to program complexity. A design that had the potential of being elegant turns out into an ugly monster by the need to manually manage memory deallocation. Not to mention the suggested use of "delete this" (p. 41). The author is "not sure why, but [...] people wince at delete this". Hint, John: objects sometimes reside on the stack. In which case delete this can have very... interesting consequences. (True, in the context of a Singleton, where allocation is controlled and cannot occur on stack, this specific problem is not present, and yet "delete this" is such an evil construct, with such horrible possible results, that I'd rather avoid it even in such controlled cases.)

And sadly, the entire discussion on the use of Singletons ignores what I've come to conlude is the pattern's worst, and most common, misuse: Singletons, in my experience, are a tempting (and in practically all cases wrong) replacement for global variables. A designer that finds a need for a global variable simply replaces it with a Singleton, and pronounces that not only he's not using globals, but rather he's using a known pattern, which must mean his design is good.

Chapter 2 is a tour-de-force of using "classical" patterns, those presented in the original Design Patterns book. The examples look a little forced, and life too simple (every problem has a corresponding pattern that fits it like a glove), and yet it is a most educating read. For one relatively simple problem, the author comes up with an elegant solution that uses no less than six patterns (Proxy, Composite, Template Method, Visitor, Mediator and Singleton) -- and suggests an enhancement using a seventh one (Observer). This discussion alone could be worth the effort of reading the book, as it examplifies the correct and practical use of patterns in real life. The end of the chapter presents a very nice kind of diagram, invented by Erich Gamma, which could be very useful indeed. This "pattern:role annotation", as Gamma calls it, allows people who are sufficiently fluent in the pattern language of design to immediately grasp the role of different objects, even in a large design.

Chapters 4 and 5 are aimed mainly for pattern developers, though this is not clear when one begins to read them. It includes an example of the Gang of Four's elaborate discussions about pattern design, with lots of quotes from e-mail messages, etc. This is interesting only to a certain extent. The discussion, basically, is about whether Multicast should be presented as a pattern in its own right, or as an adaptation of the Observer pattern. Most of the discussion seemed to be dealing with minute neuances, but the conclusion (the presentation of a whole new pattern, "Typed Message"), is a beautiful one.

The concluding chapter (5) is titled "Seven Habits of Effective Pattern Writers". The name says it all. Though some of the advice presented (e.g. number 5, "Presenting Effectively") are trivial, others (e.g. number 1, "Taking Time to Reflect") are very educating. (Don't be mislead by that simple title, "Taking Time to Reflect". Vlissides provides some real important tips under this seemingly obvious one.)

In conclusion, if you do a lot of object-oriented design, and use (or consider using) design patterns, reading this book can be a good use of your time; but unless you spend time on designing patterns, too, you might wish to simply skim the last two chapters.

Pick this book up at ThinkGeek.

For additional book reviews, please visit http://www.forum2.org/tal/books.

Tal Cohen, one of our best book reviewers thought that the Slashdot audience would appreciate Pattern Hatching: Design Patterns Applied, a book written by John Vlissides. This book is not one of the many new pattern catalogs, this book shows how patterns are applied in real life -- and also includes some interesting guidelines for would-be pattern writers. Pattern Hatching: Design Patterns Applied author John Vlissides pages 172 publisher Addison-Wesley, 06/1998 rating 7/10 reviewer Tal Cohen ISBN 0-201-43293-5 summary Not one of the many new pattern catalogs, this book shows how patterns are applied in real life -- and also includes some interesting guidelines for would-be patternwriters. Along with all the hoopla surrounding patterns these days comes more than a little confusion, consternation, and misinformation. This is partly a reflection of how new the field is to mainstream software developers even though it's not, strictly speaking, a new field. It's a fast-moving field too, creating vacuums of facts. And yes, we pattern proponents deserve some of the blame for not educating people as thoroughly as we'd like, though not for lack of trying.

John Vlissides, a member of the "Gang of Four" -- the authors of Design Patterns, presents another book on the subject. In part, this book presents some important aspects in using patterns; hence the subtitle "Design Patterns Applied" is right on the spot. Vlissides shows when certain patterns are used in real life, and even quotes a lot of e-mail from other users, showing patten advantages and, notably, weaknesses. As Vlissides states, "This book conveys something very important that's missing in the more academic and published Design Patterns book -- that patterns are the result of real, working programmers who don't get everything right the first time, and who struggle with the pragmatics of recurring design practices" (page x). Herein lies the book's greatest strength. Another part is aimed for pattern writers, rather than users. Sadly, these is no clear separation between these two aspects of the book.

The book is basically a collection of Vlissides's columns in C++ Report, and this is arguably the book's weakest point: if you're not intimately familiar with the little details of C++, you'll miss much of the action. This is sad, because the original Design Patterns book was careful to present patterns in a relatively language-independent manner, both in C++ and in Smalltalk. Here, the view is strongly biased towards C++, in ways that sometimes would annoy (or amuse) users of other languages, such as Smalltalk or Java.

Consider, for exmaple, Chapter 3: "Themes and Variations". A large portion of the chapter deals with the de-allocation problem of Singleton objects. Any programmer who uses a garbage-collecting language will be simply amused by the entire hoopla. The only conclusion from the entire discussion, one that the author himself admits (p. 69 and elsewhere), is that the lack of garbage collection greatly increases design complexity, in addition to program complexity. A design that had the potential of being elegant turns out into an ugly monster by the need to manually manage memory deallocation. Not to mention the suggested use of "delete this" (p. 41). The author is "not sure why, but [...] people wince at delete this". Hint, John: objects sometimes reside on the stack. In which case delete this can have very... interesting consequences. (True, in the context of a Singleton, where allocation is controlled and cannot occur on stack, this specific problem is not present, and yet "delete this" is such an evil construct, with such horrible possible results, that I'd rather avoid it even in such controlled cases.)

And sadly, the entire discussion on the use of Singletons ignores what I've come to conlude is the pattern's worst, and most common, misuse: Singletons, in my experience, are a tempting (and in practically all cases wrong) replacement for global variables. A designer that finds a need for a global variable simply replaces it with a Singleton, and pronounces that not only he's not using globals, but rather he's using a known pattern, which must mean his design is good.

Chapter 2 is a tour-de-force of using "classical" patterns, those presented in the original Design Patterns book. The examples look a little forced, and life too simple (every problem has a corresponding pattern that fits it like a glove), and yet it is a most educating read. For one relatively simple problem, the author comes up with an elegant solution that uses no less than six patterns (Proxy, Composite, Template Method, Visitor, Mediator and Singleton) -- and suggests an enhancement using a seventh one (Observer). This discussion alone could be worth the effort of reading the book, as it examplifies the correct and practical use of patterns in real life. The end of the chapter presents a very nice kind of diagram, invented by Erich Gamma, which could be very useful indeed. This "pattern:role annotation", as Gamma calls it, allows people who are sufficiently fluent in the pattern language of design to immediately grasp the role of different objects, even in a large design.

Chapters 4 and 5 are aimed mainly for pattern developers, though this is not clear when one begins to read them. It includes an example of the Gang of Four's elaborate discussions about pattern design, with lots of quotes from e-mail messages, etc. This is interesting only to a certain extent. The discussion, basically, is about whether Multicast should be presented as a pattern in its own right, or as an adaptation of the Observer pattern. Most of the discussion seemed to be dealing with minute neuances, but the conclusion (the presentation of a whole new pattern, "Typed Message"), is a beautiful one.

The concluding chapter (5) is titled "Seven Habits of Effective Pattern Writers". The name says it all. Though some of the advice presented (e.g. number 5, "Presenting Effectively") are trivial, others (e.g. number 1, "Taking Time to Reflect") are very educating. (Don't be mislead by that simple title, "Taking Time to Reflect". Vlissides provides some real important tips under this seemingly obvious one.)

In conclusion, if you do a lot of object-oriented design, and use (or consider using) design patterns, reading this book can be a good use of your time; but unless you spend time on designing patterns, too, you might wish to simply skim the last two chapters.

Pick this book up at ThinkGeek.

For additional book reviews, please visit http://www.forum2.org/tal/books.

Tal Cohen has taken a close look at Douglas R. Hofstadter's Godel, Escher, Bach -- 20th Anniversary Edition. He's returned to the book to try and explain what the book is really about-using a new foreword. Definitely a book worth checking out - click below to read more. Godel, Escher, Bach -- 20th Anniversary Edition author Douglas R. Hofstadter pages publisher Basic Books rating 12/10 reviewer Tal Cohen ISBN 0-465-02656-7 summary Twenty years after its original release, the author of this spectacular masterpiece clarifies, once and for all, what the book is actually about.

In an interview to Wired magazine a few years back, Douglas R. Hofstadter, author of Gödel, Escher, Bach: an Eternal Golden Braid (GEB for short) complained that most people, even those who actually read the book, couldn't tell what it's really about. Yes, it talks about music and art, mathematics and zen, biochemistry and computer languages; but none of these is what the book is really about.

This seems to be a real problem, because in the new "20th Anniversary Edition" of the book, Hofstadter says that the question "so what is this book about?" haunted him since he was scribbling the first drafts, back in 1973. Now, twenty years after its first publication (in 1979), the author decided to clarify the matter once and for all, and added a new 23-page preface that, among other things, clarifies the issue.

So -- what is this book about? The New York Times bestsellers list originally summarized it as "A scientist argues that reality is a system of interconnected brains".

Hogwash.

The Jargon File (4.1.0) says it's "a brilliant tapestry themed on the concept of encoded self-reference". Brilliant, yes; but otherwise not very accurate. Another common definition is "a book that shows how math, art, and music are really all the same thing at their core". Hofstadter says he heard this one over and over again, even by people who read the book, and it is (in his own words) "a million miles off".

My own review of the book (http://www.forum2.org/tal/books/geb.html), the single most popular page on my web site, says that the book is about "the question of consciousness and the possibility of artificial intelligence. It is a book that attempts to discover what 'self' really means".

Much closer (but I had the advantage of reading that Wired interview).

"In a word," writes Hofstadter in the new preface, "GEB is a very personal attempt to say how it is that animate beings can come out of inanimate matter. What is a self, and how can a self come out of stuff that is as selfless as a stone or a puddle?". His explanation goes on, and clarifies at least one thing: despite its beautiful playfulness, GEB is a serious book presenting a serious theory about consciousness. Despite its popularity, it is not a "popular science" book.

If you already read GEB, you're probably wondering what else is new in the 20th Anniversary Edition -- other than the new preface. Certainly, there were many possibilities. Most ideas were about additional chapters -- about progress made in the last twenty years in the field of artificial intelligence, or about machine translation, and more. There was also the idea of including a new dialogue, that was previously published elsewhere. Wilder suggestions went as far as releasing GEB with a CD-ROM including the Escher's art, Bach's works and recordings of all of GEB's dialogues by professional narrators.

None of that.

Not a word was changed; not a figure added; not even, the author admits, the few typos fixed. The book is a facsimile of the original release, with even page numbering left intact (the preface pages use a separate numbering, from P-1 to P-23). The CD-ROM suggestion was turned down because Hofstadter "intended GEB as a book, not as a multimedia circus, and a book it shall remain". The other suggestions were turned down for more delicate reasons.

But while the preface is the only change, it is a very important one. For first-time readers, it clears several aspects of the book before they commence reading. This is important, especially because GEB is anything but an easy read (some compared reading it to giving birth). For returning readers, the introduction clarifies many things, and sheds a new light on several aspects.

In addition to establishing, once and for all, a formal definition to what the book is about, the introduction also describes the history of the book, and the history of its authors for the last twenty years. You probably heard about the books he wrote later -- Metamagical Themas, Fluid Concepts and Creative Analogies, The Mind's I (as a co-editor), and Le Ton beau de Marot: in Praise of the Music of Language . These books cover much of the suggested additions to GEB: Fluid Concepts, for example, covers Hofstadter's research work, while Le Ton beau de Marot includes a lengthy discussion (or rather, a lengthy attack) on machine translation -- among many other things.

The preface also talks about GEB's translations, a suggested sex-change operation for the Tortoise, a brief account of Hofstadter's recent literary efforts, and more.

Since you probably owe yourself a re-read of the book (you did read it before, right?), the new edition is a good excuse as any to start now.

For a complete review of the original Gödel, Escher, Bach, visit http://www.forum2.org/tal/books/geb.html.

To purchase this book, head over to Amazon.

For my review of Le Ton beau de Marot, see http://www.forum2.org/tal/books/marot.html.

Tal Cohen has taken a close look at Douglas R. Hofstadter's Godel, Escher, Bach -- 20th Anniversary Edition. He's returned to the book to try and explain what the book is really about-using a new foreword. Definitely a book worth checking out - click below to read more. Godel, Escher, Bach -- 20th Anniversary Edition author Douglas R. Hofstadter pages publisher Basic Books rating 12/10 reviewer Tal Cohen ISBN 0-465-02656-7 summary Twenty years after its original release, the author of this spectacular masterpiece clarifies, once and for all, what the book is actually about.

In an interview to Wired magazine a few years back, Douglas R. Hofstadter, author of Gödel, Escher, Bach: an Eternal Golden Braid (GEB for short) complained that most people, even those who actually read the book, couldn't tell what it's really about. Yes, it talks about music and art, mathematics and zen, biochemistry and computer languages; but none of these is what the book is really about.

This seems to be a real problem, because in the new "20th Anniversary Edition" of the book, Hofstadter says that the question "so what is this book about?" haunted him since he was scribbling the first drafts, back in 1973. Now, twenty years after its first publication (in 1979), the author decided to clarify the matter once and for all, and added a new 23-page preface that, among other things, clarifies the issue.

So -- what is this book about? The New York Times bestsellers list originally summarized it as "A scientist argues that reality is a system of interconnected brains".

Hogwash.

The Jargon File (4.1.0) says it's "a brilliant tapestry themed on the concept of encoded self-reference". Brilliant, yes; but otherwise not very accurate. Another common definition is "a book that shows how math, art, and music are really all the same thing at their core". Hofstadter says he heard this one over and over again, even by people who read the book, and it is (in his own words) "a million miles off".

My own review of the book (http://www.forum2.org/tal/books/geb.html), the single most popular page on my web site, says that the book is about "the question of consciousness and the possibility of artificial intelligence. It is a book that attempts to discover what 'self' really means".

Much closer (but I had the advantage of reading that Wired interview).

"In a word," writes Hofstadter in the new preface, "GEB is a very personal attempt to say how it is that animate beings can come out of inanimate matter. What is a self, and how can a self come out of stuff that is as selfless as a stone or a puddle?". His explanation goes on, and clarifies at least one thing: despite its beautiful playfulness, GEB is a serious book presenting a serious theory about consciousness. Despite its popularity, it is not a "popular science" book.

If you already read GEB, you're probably wondering what else is new in the 20th Anniversary Edition -- other than the new preface. Certainly, there were many possibilities. Most ideas were about additional chapters -- about progress made in the last twenty years in the field of artificial intelligence, or about machine translation, and more. There was also the idea of including a new dialogue, that was previously published elsewhere. Wilder suggestions went as far as releasing GEB with a CD-ROM including the Escher's art, Bach's works and recordings of all of GEB's dialogues by professional narrators.

None of that.

Not a word was changed; not a figure added; not even, the author admits, the few typos fixed. The book is a facsimile of the original release, with even page numbering left intact (the preface pages use a separate numbering, from P-1 to P-23). The CD-ROM suggestion was turned down because Hofstadter "intended GEB as a book, not as a multimedia circus, and a book it shall remain". The other suggestions were turned down for more delicate reasons.

But while the preface is the only change, it is a very important one. For first-time readers, it clears several aspects of the book before they commence reading. This is important, especially because GEB is anything but an easy read (some compared reading it to giving birth). For returning readers, the introduction clarifies many things, and sheds a new light on several aspects.

In addition to establishing, once and for all, a formal definition to what the book is about, the introduction also describes the history of the book, and the history of its authors for the last twenty years. You probably heard about the books he wrote later -- Metamagical Themas, Fluid Concepts and Creative Analogies, The Mind's I (as a co-editor), and Le Ton beau de Marot: in Praise of the Music of Language . These books cover much of the suggested additions to GEB: Fluid Concepts, for example, covers Hofstadter's research work, while Le Ton beau de Marot includes a lengthy discussion (or rather, a lengthy attack) on machine translation -- among many other things.

The preface also talks about GEB's translations, a suggested sex-change operation for the Tortoise, a brief account of Hofstadter's recent literary efforts, and more.

Since you probably owe yourself a re-read of the book (you did read it before, right?), the new edition is a good excuse as any to start now.

For a complete review of the original Gödel, Escher, Bach, visit http://www.forum2.org/tal/books/geb.html.

To purchase this book, head over to Amazon.

For my review of Le Ton beau de Marot, see http://www.forum2.org/tal/books/marot.html.

Tal Cohen has taken a close look at Douglas R. Hofstadter's Godel, Escher, Bach -- 20th Anniversary Edition. He's returned to the book to try and explain what the book is really about-using a new foreword. Definitely a book worth checking out - click below to read more. Godel, Escher, Bach -- 20th Anniversary Edition author Douglas R. Hofstadter pages publisher Basic Books rating 12/10 reviewer Tal Cohen ISBN 0-465-02656-7 summary Twenty years after its original release, the author of this spectacular masterpiece clarifies, once and for all, what the book is actually about.

In an interview to Wired magazine a few years back, Douglas R. Hofstadter, author of Gödel, Escher, Bach: an Eternal Golden Braid (GEB for short) complained that most people, even those who actually read the book, couldn't tell what it's really about. Yes, it talks about music and art, mathematics and zen, biochemistry and computer languages; but none of these is what the book is really about.

This seems to be a real problem, because in the new "20th Anniversary Edition" of the book, Hofstadter says that the question "so what is this book about?" haunted him since he was scribbling the first drafts, back in 1973. Now, twenty years after its first publication (in 1979), the author decided to clarify the matter once and for all, and added a new 23-page preface that, among other things, clarifies the issue.

So -- what is this book about? The New York Times bestsellers list originally summarized it as "A scientist argues that reality is a system of interconnected brains".

Hogwash.

The Jargon File (4.1.0) says it's "a brilliant tapestry themed on the concept of encoded self-reference". Brilliant, yes; but otherwise not very accurate. Another common definition is "a book that shows how math, art, and music are really all the same thing at their core". Hofstadter says he heard this one over and over again, even by people who read the book, and it is (in his own words) "a million miles off".

My own review of the book (http://www.forum2.org/tal/books/geb.html), the single most popular page on my web site, says that the book is about "the question of consciousness and the possibility of artificial intelligence. It is a book that attempts to discover what 'self' really means".

Much closer (but I had the advantage of reading that Wired interview).

"In a word," writes Hofstadter in the new preface, "GEB is a very personal attempt to say how it is that animate beings can come out of inanimate matter. What is a self, and how can a self come out of stuff that is as selfless as a stone or a puddle?". His explanation goes on, and clarifies at least one thing: despite its beautiful playfulness, GEB is a serious book presenting a serious theory about consciousness. Despite its popularity, it is not a "popular science" book.

If you already read GEB, you're probably wondering what else is new in the 20th Anniversary Edition -- other than the new preface. Certainly, there were many possibilities. Most ideas were about additional chapters -- about progress made in the last twenty years in the field of artificial intelligence, or about machine translation, and more. There was also the idea of including a new dialogue, that was previously published elsewhere. Wilder suggestions went as far as releasing GEB with a CD-ROM including the Escher's art, Bach's works and recordings of all of GEB's dialogues by professional narrators.

None of that.

Not a word was changed; not a figure added; not even, the author admits, the few typos fixed. The book is a facsimile of the original release, with even page numbering left intact (the preface pages use a separate numbering, from P-1 to P-23). The CD-ROM suggestion was turned down because Hofstadter "intended GEB as a book, not as a multimedia circus, and a book it shall remain". The other suggestions were turned down for more delicate reasons.

But while the preface is the only change, it is a very important one. For first-time readers, it clears several aspects of the book before they commence reading. This is important, especially because GEB is anything but an easy read (some compared reading it to giving birth). For returning readers, the introduction clarifies many things, and sheds a new light on several aspects.

In addition to establishing, once and for all, a formal definition to what the book is about, the introduction also describes the history of the book, and the history of its authors for the last twenty years. You probably heard about the books he wrote later -- Metamagical Themas, Fluid Concepts and Creative Analogies, The Mind's I (as a co-editor), and Le Ton beau de Marot: in Praise of the Music of Language . These books cover much of the suggested additions to GEB: Fluid Concepts, for example, covers Hofstadter's research work, while Le Ton beau de Marot includes a lengthy discussion (or rather, a lengthy attack) on machine translation -- among many other things.

The preface also talks about GEB's translations, a suggested sex-change operation for the Tortoise, a brief account of Hofstadter's recent literary efforts, and more.

Since you probably owe yourself a re-read of the book (you did read it before, right?), the new edition is a good excuse as any to start now.

For a complete review of the original Gödel, Escher, Bach, visit http://www.forum2.org/tal/books/geb.html.

To purchase this book, head over to Amazon.

For my review of Le Ton beau de Marot, see http://www.forum2.org/tal/books/marot.html.

Tal Cohen has taken a close look at Douglas R. Hofstadter's Godel, Escher, Bach -- 20th Anniversary Edition. He's returned to the book to try and explain what the book is really about-using a new foreword. Definitely a book worth checking out - click below to read more. Godel, Escher, Bach -- 20th Anniversary Edition author Douglas R. Hofstadter pages publisher Basic Books rating 12/10 reviewer Tal Cohen ISBN 0-465-02656-7 summary Twenty years after its original release, the author of this spectacular masterpiece clarifies, once and for all, what the book is actually about.

In an interview to Wired magazine a few years back, Douglas R. Hofstadter, author of Gödel, Escher, Bach: an Eternal Golden Braid (GEB for short) complained that most people, even those who actually read the book, couldn't tell what it's really about. Yes, it talks about music and art, mathematics and zen, biochemistry and computer languages; but none of these is what the book is really about.

This seems to be a real problem, because in the new "20th Anniversary Edition" of the book, Hofstadter says that the question "so what is this book about?" haunted him since he was scribbling the first drafts, back in 1973. Now, twenty years after its first publication (in 1979), the author decided to clarify the matter once and for all, and added a new 23-page preface that, among other things, clarifies the issue.

So -- what is this book about? The New York Times bestsellers list originally summarized it as "A scientist argues that reality is a system of interconnected brains".

Hogwash.

The Jargon File (4.1.0) says it's "a brilliant tapestry themed on the concept of encoded self-reference". Brilliant, yes; but otherwise not very accurate. Another common definition is "a book that shows how math, art, and music are really all the same thing at their core". Hofstadter says he heard this one over and over again, even by people who read the book, and it is (in his own words) "a million miles off".

My own review of the book (http://www.forum2.org/tal/books/geb.html), the single most popular page on my web site, says that the book is about "the question of consciousness and the possibility of artificial intelligence. It is a book that attempts to discover what 'self' really means".

Much closer (but I had the advantage of reading that Wired interview).

"In a word," writes Hofstadter in the new preface, "GEB is a very personal attempt to say how it is that animate beings can come out of inanimate matter. What is a self, and how can a self come out of stuff that is as selfless as a stone or a puddle?". His explanation goes on, and clarifies at least one thing: despite its beautiful playfulness, GEB is a serious book presenting a serious theory about consciousness. Despite its popularity, it is not a "popular science" book.

If you already read GEB, you're probably wondering what else is new in the 20th Anniversary Edition -- other than the new preface. Certainly, there were many possibilities. Most ideas were about additional chapters -- about progress made in the last twenty years in the field of artificial intelligence, or about machine translation, and more. There was also the idea of including a new dialogue, that was previously published elsewhere. Wilder suggestions went as far as releasing GEB with a CD-ROM including the Escher's art, Bach's works and recordings of all of GEB's dialogues by professional narrators.

None of that.

Not a word was changed; not a figure added; not even, the author admits, the few typos fixed. The book is a facsimile of the original release, with even page numbering left intact (the preface pages use a separate numbering, from P-1 to P-23). The CD-ROM suggestion was turned down because Hofstadter "intended GEB as a book, not as a multimedia circus, and a book it shall remain". The other suggestions were turned down for more delicate reasons.

But while the preface is the only change, it is a very important one. For first-time readers, it clears several aspects of the book before they commence reading. This is important, especially because GEB is anything but an easy read (some compared reading it to giving birth). For returning readers, the introduction clarifies many things, and sheds a new light on several aspects.

In addition to establishing, once and for all, a formal definition to what the book is about, the introduction also describes the history of the book, and the history of its authors for the last twenty years. You probably heard about the books he wrote later -- Metamagical Themas, Fluid Concepts and Creative Analogies, The Mind's I (as a co-editor), and Le Ton beau de Marot: in Praise of the Music of Language . These books cover much of the suggested additions to GEB: Fluid Concepts, for example, covers Hofstadter's research work, while Le Ton beau de Marot includes a lengthy discussion (or rather, a lengthy attack) on machine translation -- among many other things.

The preface also talks about GEB's translations, a suggested sex-change operation for the Tortoise, a brief account of Hofstadter's recent literary efforts, and more.

Since you probably owe yourself a re-read of the book (you did read it before, right?), the new edition is a good excuse as any to start now.

For a complete review of the original Gödel, Escher, Bach, visit http://www.forum2.org/tal/books/geb.html.

To purchase this book, head over to Amazon.

For my review of Le Ton beau de Marot, see http://www.forum2.org/tal/books/marot.html.

Tal Cohen has taken a close look at Douglas R. Hofstadter's Godel, Escher, Bach -- 20th Anniversary Edition. He's returned to the book to try and explain what the book is really about-using a new foreword. Definitely a book worth checking out - click below to read more. Godel, Escher, Bach -- 20th Anniversary Edition author Douglas R. Hofstadter pages publisher Basic Books rating 12/10 reviewer Tal Cohen ISBN 0-465-02656-7 summary Twenty years after its original release, the author of this spectacular masterpiece clarifies, once and for all, what the book is actually about.

In an interview to Wired magazine a few years back, Douglas R. Hofstadter, author of Gödel, Escher, Bach: an Eternal Golden Braid (GEB for short) complained that most people, even those who actually read the book, couldn't tell what it's really about. Yes, it talks about music and art, mathematics and zen, biochemistry and computer languages; but none of these is what the book is really about.

This seems to be a real problem, because in the new "20th Anniversary Edition" of the book, Hofstadter says that the question "so what is this book about?" haunted him since he was scribbling the first drafts, back in 1973. Now, twenty years after its first publication (in 1979), the author decided to clarify the matter once and for all, and added a new 23-page preface that, among other things, clarifies the issue.

So -- what is this book about? The New York Times bestsellers list originally summarized it as "A scientist argues that reality is a system of interconnected brains".

Hogwash.

The Jargon File (4.1.0) says it's "a brilliant tapestry themed on the concept of encoded self-reference". Brilliant, yes; but otherwise not very accurate. Another common definition is "a book that shows how math, art, and music are really all the same thing at their core". Hofstadter says he heard this one over and over again, even by people who read the book, and it is (in his own words) "a million miles off".

My own review of the book (http://www.forum2.org/tal/books/geb.html), the single most popular page on my web site, says that the book is about "the question of consciousness and the possibility of artificial intelligence. It is a book that attempts to discover what 'self' really means".

Much closer (but I had the advantage of reading that Wired interview).

"In a word," writes Hofstadter in the new preface, "GEB is a very personal attempt to say how it is that animate beings can come out of inanimate matter. What is a self, and how can a self come out of stuff that is as selfless as a stone or a puddle?". His explanation goes on, and clarifies at least one thing: despite its beautiful playfulness, GEB is a serious book presenting a serious theory about consciousness. Despite its popularity, it is not a "popular science" book.

If you already read GEB, you're probably wondering what else is new in the 20th Anniversary Edition -- other than the new preface. Certainly, there were many possibilities. Most ideas were about additional chapters -- about progress made in the last twenty years in the field of artificial intelligence, or about machine translation, and more. There was also the idea of including a new dialogue, that was previously published elsewhere. Wilder suggestions went as far as releasing GEB with a CD-ROM including the Escher's art, Bach's works and recordings of all of GEB's dialogues by professional narrators.

None of that.

Not a word was changed; not a figure added; not even, the author admits, the few typos fixed. The book is a facsimile of the original release, with even page numbering left intact (the preface pages use a separate numbering, from P-1 to P-23). The CD-ROM suggestion was turned down because Hofstadter "intended GEB as a book, not as a multimedia circus, and a book it shall remain". The other suggestions were turned down for more delicate reasons.

But while the preface is the only change, it is a very important one. For first-time readers, it clears several aspects of the book before they commence reading. This is important, especially because GEB is anything but an easy read (some compared reading it to giving birth). For returning readers, the introduction clarifies many things, and sheds a new light on several aspects.

In addition to establishing, once and for all, a formal definition to what the book is about, the introduction also describes the history of the book, and the history of its authors for the last twenty years. You probably heard about the books he wrote later -- Metamagical Themas, Fluid Concepts and Creative Analogies, The Mind's I (as a co-editor), and Le Ton beau de Marot: in Praise of the Music of Language . These books cover much of the suggested additions to GEB: Fluid Concepts, for example, covers Hofstadter's research work, while Le Ton beau de Marot includes a lengthy discussion (or rather, a lengthy attack) on machine translation -- among many other things.

The preface also talks about GEB's translations, a suggested sex-change operation for the Tortoise, a brief account of Hofstadter's recent literary efforts, and more.

Since you probably owe yourself a re-read of the book (you did read it before, right?), the new edition is a good excuse as any to start now.

For a complete review of the original Gödel, Escher, Bach, visit http://www.forum2.org/tal/books/geb.html.

To purchase this book, head over to Amazon.

For my review of Le Ton beau de Marot, see http://www.forum2.org/tal/books/marot.html.

Tal Cohen has taken a close look at Douglas R. Hofstadter's Godel, Escher, Bach -- 20th Anniversary Edition. He's returned to the book to try and explain what the book is really about-using a new foreword. Definitely a book worth checking out - click below to read more. Godel, Escher, Bach -- 20th Anniversary Edition author Douglas R. Hofstadter pages publisher Basic Books rating 12/10 reviewer Tal Cohen ISBN 0-465-02656-7 summary Twenty years after its original release, the author of this spectacular masterpiece clarifies, once and for all, what the book is actually about.

In an interview to Wired magazine a few years back, Douglas R. Hofstadter, author of Gödel, Escher, Bach: an Eternal Golden Braid (GEB for short) complained that most people, even those who actually read the book, couldn't tell what it's really about. Yes, it talks about music and art, mathematics and zen, biochemistry and computer languages; but none of these is what the book is really about.

This seems to be a real problem, because in the new "20th Anniversary Edition" of the book, Hofstadter says that the question "so what is this book about?" haunted him since he was scribbling the first drafts, back in 1973. Now, twenty years after its first publication (in 1979), the author decided to clarify the matter once and for all, and added a new 23-page preface that, among other things, clarifies the issue.

So -- what is this book about? The New York Times bestsellers list originally summarized it as "A scientist argues that reality is a system of interconnected brains".

Hogwash.

The Jargon File (4.1.0) says it's "a brilliant tapestry themed on the concept of encoded self-reference". Brilliant, yes; but otherwise not very accurate. Another common definition is "a book that shows how math, art, and music are really all the same thing at their core". Hofstadter says he heard this one over and over again, even by people who read the book, and it is (in his own words) "a million miles off".

My own review of the book (http://www.forum2.org/tal/books/geb.html), the single most popular page on my web site, says that the book is about "the question of consciousness and the possibility of artificial intelligence. It is a book that attempts to discover what 'self' really means".

Much closer (but I had the advantage of reading that Wired interview).

"In a word," writes Hofstadter in the new preface, "GEB is a very personal attempt to say how it is that animate beings can come out of inanimate matter. What is a self, and how can a self come out of stuff that is as selfless as a stone or a puddle?". His explanation goes on, and clarifies at least one thing: despite its beautiful playfulness, GEB is a serious book presenting a serious theory about consciousness. Despite its popularity, it is not a "popular science" book.

If you already read GEB, you're probably wondering what else is new in the 20th Anniversary Edition -- other than the new preface. Certainly, there were many possibilities. Most ideas were about additional chapters -- about progress made in the last twenty years in the field of artificial intelligence, or about machine translation, and more. There was also the idea of including a new dialogue, that was previously published elsewhere. Wilder suggestions went as far as releasing GEB with a CD-ROM including the Escher's art, Bach's works and recordings of all of GEB's dialogues by professional narrators.

None of that.

Not a word was changed; not a figure added; not even, the author admits, the few typos fixed. The book is a facsimile of the original release, with even page numbering left intact (the preface pages use a separate numbering, from P-1 to P-23). The CD-ROM suggestion was turned down because Hofstadter "intended GEB as a book, not as a multimedia circus, and a book it shall remain". The other suggestions were turned down for more delicate reasons.

But while the preface is the only change, it is a very important one. For first-time readers, it clears several aspects of the book before they commence reading. This is important, especially because GEB is anything but an easy read (some compared reading it to giving birth). For returning readers, the introduction clarifies many things, and sheds a new light on several aspects.

In addition to establishing, once and for all, a formal definition to what the book is about, the introduction also describes the history of the book, and the history of its authors for the last twenty years. You probably heard about the books he wrote later -- Metamagical Themas, Fluid Concepts and Creative Analogies, The Mind's I (as a co-editor), and Le Ton beau de Marot: in Praise of the Music of Language . These books cover much of the suggested additions to GEB: Fluid Concepts, for example, covers Hofstadter's research work, while Le Ton beau de Marot includes a lengthy discussion (or rather, a lengthy attack) on machine translation -- among many other things.

The preface also talks about GEB's translations, a suggested sex-change operation for the Tortoise, a brief account of Hofstadter's recent literary efforts, and more.

Since you probably owe yourself a re-read of the book (you did read it before, right?), the new edition is a good excuse as any to start now.

For a complete review of the original Gödel, Escher, Bach, visit http://www.forum2.org/tal/books/geb.html.

To purchase this book, head over to Amazon.

For my review of Le Ton beau de Marot, see http://www.forum2.org/tal/books/marot.html.

Tal Cohen, author of a number of book reviews in his own right, has sent over a review of Bruce Schneier's Applied Cryptography, 2nd Edition. One of the best introductions to the field of cryptography this is a book well worth reading, even for those who simply want a better understanding of the potentials about cryptography, and what it's all about. Applied Cryptography, 2nd Edition author Bruce Schneier pages publisher John Wiley & Sons rating 8/10 reviewer Tal Cohen ISBN 0-471-11709-9 summary A fantastic introduction and a handy reference on one of computer science's most interesting fields.

More than any other field in computer science, cryptography is associated with computer warfare. Recent international treaties define cryptographic algorithms as weapons, and the laws of many countries prohibit either the development, the usage, or the export of cryptographic algorithms. Yet while feared by governments, cryptography is one of the most fascinating -- and useful -- fields of algorithmics.

The whole point of cryptography is to solve problems. (Actually, that's the whole point of computers -- something many peopletend to forget.) Cryptography solves problems that involve secrecy, authentication, integrity, and dishonest people. You can learn all about cryptographic algorithms and techniques, but these are academic unless they can solve a problem.

Bruce Schneier's Applied Cryptography, in its second edition, is probably the best introduction to the field. Schneier is not merely an excellent technical writer, but also a researcherin the field; for example, he developed the public-domain Blowfish encryption algorithm. But unlike many works by other researchers, Schneier's work does not read like a dry paper for a scientific journal. His writing is very enjoyable (though the jokes are overdone at times) and his explanations are almost always lucid.

Breaking a plate is a good example of a one-way function. It is easy to smash a plate into a thousand tiny pieces. However, it's not easy to put all those tiny pieces back together into a plate. [...]

So, what good are one-way functions? We can't use them for encryption as is. A message encrypted with the one-way function isn't useful; no one could decrypt it. (Exercise: Write a message of a plate, smash the plate into bits, and then give the bits to a friend. Ask your friend to read the message. Observe how impressed he is with the one-way function.) For public-key cryptography, we need something else.

Generally, the book covers four main subjects: protocols, algorithms, source code (in C), and politics. As the title indicates, the book is intended to people who actually wish to apply cryptographic methods to their programs, and so the theoretical discussions and mostly at introductory level - sufficient to make you understand how an algorithm works and what are its benefits and potential weaknesses, but without elaborate mathematical proofs, for example.

Part I of the book, "Cryptographic Protocols", includes five chapters: building blocks, basic protocols (like key exchange and authentication), intermediate protocols (timestamping, fair coin flips, key escrew, etc.), advanced (zero-knowledge proofs, simultaneous contract signing, digital certified mail, etc.) and esoteric ones (like secure elections and anonymous message broadcast).

Part II, "Cryptographic Techniques", deals with such issues as key length, key management, and methods of employing algorithms. The longest section, Part III, spans 13 chapters -- "Cryptographic Algorithms". The algorithms covered include DES and its variants,Skipjack, Lucifer, LOKI, RC2, RC4, RC5 (that's the cow in your tray-bin!), IDEA Blowfish, RSA and many others. The greatest detail is given to the venerable old DES, but the information about other protocols (over 50 in all, including blockDES, but the information about other protocols (over 50 in all, including block ciphers, stream ciphers, random-sequence generators, one-way hash functions, public key algorithms, and more) is sufficiently detailed for you to decide which best suites your needs. And if you need more information, an outstandingl$ detailed list of over 1,600 references is included.

As in most texts about cryptography, protocols and algorithms are described using the merry cast of Alice (side A), Bob (side B), Eve the eavesdropper, Mallory the malicious attacker, and their other friends and foes. This makes descriptions much easier, since once you get used to these Dramatis Personae (which happens rather quickly), you immediately know who plays what role in each scene, without wasting time on repeated explanations. Schneier brings those characters to life in numerous examples of the pros and cons of various approaches.

Part IV, "The Real World", deals with two subjects: sample implementations in actual products, and politics, including history and legal issues. The history of cryptography is much longer than that of computer science: from secret codes to invisible inks, encoded messages were here for a very long time indeed. On the other hand, cracking cryptographic codes was among the earliest uses of computers, back in WWII (as anyone familiar with the story of Alan Turing knows).

One section in chapter 25 lists the import and export limitations on cryptography in different places around the globe. The most interesting entry is for my own country, Israel, which (according to Schneier) "has import restrictions, but no one seems to know what they are."

The final section, "Source Code", includes over 50 pages of sources in C for several algorithms: DES, LOKI91, IDEA, GOST, Blowfish, 3-Way, RC5, A5 and SEAL. It looks insane that a book with so many lines of source is not accompanied by a CD; but then you realize that what's insane is not the boo$ but export laws, which allow cryptographic algorithms to be distributed in prin$ -- but not on electronic media. Consider, for example, how Phil Zimmermann's PG$ was legally exported from the US to the rest of the world: the sources were printed in a one-copy book, which was mailed to Europe, scanned in and recompiled.

If you live in the States, you can order a set of 3 floppies directly from Schneier, with sources for most of the algorithms discussed in the book (and more).

Anyone cares to mail me a printout?

Purchase this book at Computer Literay and help Slashdot.

For more information about this book, see the sidebar of http://www.forum2.org/tal/books/crypto.html.

For additional book reviews, please visit http://www.forum2.org/tal/books.

Tal Cohen, author of a number of book reviews in his own right, has sent over a review of Bruce Schneier's Applied Cryptography, 2nd Edition. One of the best introductions to the field of cryptography this is a book well worth reading, even for those who simply want a better understanding of the potentials about cryptography, and what it's all about. Applied Cryptography, 2nd Edition author Bruce Schneier pages publisher John Wiley & Sons rating 8/10 reviewer Tal Cohen ISBN 0-471-11709-9 summary A fantastic introduction and a handy reference on one of computer science's most interesting fields.

More than any other field in computer science, cryptography is associated with computer warfare. Recent international treaties define cryptographic algorithms as weapons, and the laws of many countries prohibit either the development, the usage, or the export of cryptographic algorithms. Yet while feared by governments, cryptography is one of the most fascinating -- and useful -- fields of algorithmics.

The whole point of cryptography is to solve problems. (Actually, that's the whole point of computers -- something many peopletend to forget.) Cryptography solves problems that involve secrecy, authentication, integrity, and dishonest people. You can learn all about cryptographic algorithms and techniques, but these are academic unless they can solve a problem.

Bruce Schneier's Applied Cryptography, in its second edition, is probably the best introduction to the field. Schneier is not merely an excellent technical writer, but also a researcherin the field; for example, he developed the public-domain Blowfish encryption algorithm. But unlike many works by other researchers, Schneier's work does not read like a dry paper for a scientific journal. His writing is very enjoyable (though the jokes are overdone at times) and his explanations are almost always lucid.

Breaking a plate is a good example of a one-way function. It is easy to smash a plate into a thousand tiny pieces. However, it's not easy to put all those tiny pieces back together into a plate. [...]

So, what good are one-way functions? We can't use them for encryption as is. A message encrypted with the one-way function isn't useful; no one could decrypt it. (Exercise: Write a message of a plate, smash the plate into bits, and then give the bits to a friend. Ask your friend to read the message. Observe how impressed he is with the one-way function.) For public-key cryptography, we need something else.

Generally, the book covers four main subjects: protocols, algorithms, source code (in C), and politics. As the title indicates, the book is intended to people who actually wish to apply cryptographic methods to their programs, and so the theoretical discussions and mostly at introductory level - sufficient to make you understand how an algorithm works and what are its benefits and potential weaknesses, but without elaborate mathematical proofs, for example.

Part I of the book, "Cryptographic Protocols", includes five chapters: building blocks, basic protocols (like key exchange and authentication), intermediate protocols (timestamping, fair coin flips, key escrew, etc.), advanced (zero-knowledge proofs, simultaneous contract signing, digital certified mail, etc.) and esoteric ones (like secure elections and anonymous message broadcast).

Part II, "Cryptographic Techniques", deals with such issues as key length, key management, and methods of employing algorithms. The longest section, Part III, spans 13 chapters -- "Cryptographic Algorithms". The algorithms covered include DES and its variants,Skipjack, Lucifer, LOKI, RC2, RC4, RC5 (that's the cow in your tray-bin!), IDEA Blowfish, RSA and many others. The greatest detail is given to the venerable old DES, but the information about other protocols (over 50 in all, including blockDES, but the information about other protocols (over 50 in all, including block ciphers, stream ciphers, random-sequence generators, one-way hash functions, public key algorithms, and more) is sufficiently detailed for you to decide which best suites your needs. And if you need more information, an outstandingl$ detailed list of over 1,600 references is included.

As in most texts about cryptography, protocols and algorithms are described using the merry cast of Alice (side A), Bob (side B), Eve the eavesdropper, Mallory the malicious attacker, and their other friends and foes. This makes descriptions much easier, since once you get used to these Dramatis Personae (which happens rather quickly), you immediately know who plays what role in each scene, without wasting time on repeated explanations. Schneier brings those characters to life in numerous examples of the pros and cons of various approaches.

Part IV, "The Real World", deals with two subjects: sample implementations in actual products, and politics, including history and legal issues. The history of cryptography is much longer than that of computer science: from secret codes to invisible inks, encoded messages were here for a very long time indeed. On the other hand, cracking cryptographic codes was among the earliest uses of computers, back in WWII (as anyone familiar with the story of Alan Turing knows).

One section in chapter 25 lists the import and export limitations on cryptography in different places around the globe. The most interesting entry is for my own country, Israel, which (according to Schneier) "has import restrictions, but no one seems to know what they are."

The final section, "Source Code", includes over 50 pages of sources in C for several algorithms: DES, LOKI91, IDEA, GOST, Blowfish, 3-Way, RC5, A5 and SEAL. It looks insane that a book with so many lines of source is not accompanied by a CD; but then you realize that what's insane is not the boo$ but export laws, which allow cryptographic algorithms to be distributed in prin$ -- but not on electronic media. Consider, for example, how Phil Zimmermann's PG$ was legally exported from the US to the rest of the world: the sources were printed in a one-copy book, which was mailed to Europe, scanned in and recompiled.

If you live in the States, you can order a set of 3 floppies directly from Schneier, with sources for most of the algorithms discussed in the book (and more).

Anyone cares to mail me a printout?

Purchase this book at Computer Literay and help Slashdot.

For more information about this book, see the sidebar of http://www.forum2.org/tal/books/crypto.html.

For additional book reviews, please visit http://www.forum2.org/tal/books.

Tal Cohen, author of a number of book reviews in his own right, has sent over a review of Bruce Schneier's Applied Cryptography, 2nd Edition. One of the best introductions to the field of cryptography this is a book well worth reading, even for those who simply want a better understanding of the potentials about cryptography, and what it's all about. Applied Cryptography, 2nd Edition author Bruce Schneier pages publisher John Wiley & Sons rating 8/10 reviewer Tal Cohen ISBN 0-471-11709-9 summary A fantastic introduction and a handy reference on one of computer science's most interesting fields.

More than any other field in computer science, cryptography is associated with computer warfare. Recent international treaties define cryptographic algorithms as weapons, and the laws of many countries prohibit either the development, the usage, or the export of cryptographic algorithms. Yet while feared by governments, cryptography is one of the most fascinating -- and useful -- fields of algorithmics.

The whole point of cryptography is to solve problems. (Actually, that's the whole point of computers -- something many peopletend to forget.) Cryptography solves problems that involve secrecy, authentication, integrity, and dishonest people. You can learn all about cryptographic algorithms and techniques, but these are academic unless they can solve a problem.

Bruce Schneier's Applied Cryptography, in its second edition, is probably the best introduction to the field. Schneier is not merely an excellent technical writer, but also a researcherin the field; for example, he developed the public-domain Blowfish encryption algorithm. But unlike many works by other researchers, Schneier's work does not read like a dry paper for a scientific journal. His writing is very enjoyable (though the jokes are overdone at times) and his explanations are almost always lucid.

Breaking a plate is a good example of a one-way function. It is easy to smash a plate into a thousand tiny pieces. However, it's not easy to put all those tiny pieces back together into a plate. [...]

So, what good are one-way functions? We can't use them for encryption as is. A message encrypted with the one-way function isn't useful; no one could decrypt it. (Exercise: Write a message of a plate, smash the plate into bits, and then give the bits to a friend. Ask your friend to read the message. Observe how impressed he is with the one-way function.) For public-key cryptography, we need something else.

Generally, the book covers four main subjects: protocols, algorithms, source code (in C), and politics. As the title indicates, the book is intended to people who actually wish to apply cryptographic methods to their programs, and so the theoretical discussions and mostly at introductory level - sufficient to make you understand how an algorithm works and what are its benefits and potential weaknesses, but without elaborate mathematical proofs, for example.

Part I of the book, "Cryptographic Protocols", includes five chapters: building blocks, basic protocols (like key exchange and authentication), intermediate protocols (timestamping, fair coin flips, key escrew, etc.), advanced (zero-knowledge proofs, simultaneous contract signing, digital certified mail, etc.) and esoteric ones (like secure elections and anonymous message broadcast).

Part II, "Cryptographic Techniques", deals with such issues as key length, key management, and methods of employing algorithms. The longest section, Part III, spans 13 chapters -- "Cryptographic Algorithms". The algorithms covered include DES and its variants,Skipjack, Lucifer, LOKI, RC2, RC4, RC5 (that's the cow in your tray-bin!), IDEA Blowfish, RSA and many others. The greatest detail is given to the venerable old DES, but the information about other protocols (over 50 in all, including blockDES, but the information about other protocols (over 50 in all, including block ciphers, stream ciphers, random-sequence generators, one-way hash functions, public key algorithms, and more) is sufficiently detailed for you to decide which best suites your needs. And if you need more information, an outstandingl$ detailed list of over 1,600 references is included.

As in most texts about cryptography, protocols and algorithms are described using the merry cast of Alice (side A), Bob (side B), Eve the eavesdropper, Mallory the malicious attacker, and their other friends and foes. This makes descriptions much easier, since once you get used to these Dramatis Personae (which happens rather quickly), you immediately know who plays what role in each scene, without wasting time on repeated explanations. Schneier brings those characters to life in numerous examples of the pros and cons of various approaches.

Part IV, "The Real World", deals with two subjects: sample implementations in actual products, and politics, including history and legal issues. The history of cryptography is much longer than that of computer science: from secret codes to invisible inks, encoded messages were here for a very long time indeed. On the other hand, cracking cryptographic codes was among the earliest uses of computers, back in WWII (as anyone familiar with the story of Alan Turing knows).

One section in chapter 25 lists the import and export limitations on cryptography in different places around the globe. The most interesting entry is for my own country, Israel, which (according to Schneier) "has import restrictions, but no one seems to know what they are."

The final section, "Source Code", includes over 50 pages of sources in C for several algorithms: DES, LOKI91, IDEA, GOST, Blowfish, 3-Way, RC5, A5 and SEAL. It looks insane that a book with so many lines of source is not accompanied by a CD; but then you realize that what's insane is not the boo$ but export laws, which allow cryptographic algorithms to be distributed in prin$ -- but not on electronic media. Consider, for example, how Phil Zimmermann's PG$ was legally exported from the US to the rest of the world: the sources were printed in a one-copy book, which was mailed to Europe, scanned in and recompiled.

If you live in the States, you can order a set of 3 floppies directly from Schneier, with sources for most of the algorithms discussed in the book (and more).

Anyone cares to mail me a printout?

Purchase this book at Computer Literay and help Slashdot.

For more information about this book, see the sidebar of http://www.forum2.org/tal/books/crypto.html.

For additional book reviews, please visit http://www.forum2.org/tal/books.

Tal Cohen, author of a number of book reviews in his own right, has sent over a review of Bruce Schneier's Applied Cryptography, 2nd Edition. One of the best introductions to the field of cryptography this is a book well worth reading, even for those who simply want a better understanding of the potentials about cryptography, and what it's all about. Applied Cryptography, 2nd Edition author Bruce Schneier pages publisher John Wiley & Sons rating 8/10 reviewer Tal Cohen ISBN 0-471-11709-9 summary A fantastic introduction and a handy reference on one of computer science's most interesting fields.

More than any other field in computer science, cryptography is associated with computer warfare. Recent international treaties define cryptographic algorithms as weapons, and the laws of many countries prohibit either the development, the usage, or the export of cryptographic algorithms. Yet while feared by governments, cryptography is one of the most fascinating -- and useful -- fields of algorithmics.

The whole point of cryptography is to solve problems. (Actually, that's the whole point of computers -- something many peopletend to forget.) Cryptography solves problems that involve secrecy, authentication, integrity, and dishonest people. You can learn all about cryptographic algorithms and techniques, but these are academic unless they can solve a problem.

Bruce Schneier's Applied Cryptography, in its second edition, is probably the best introduction to the field. Schneier is not merely an excellent technical writer, but also a researcherin the field; for example, he developed the public-domain Blowfish encryption algorithm. But unlike many works by other researchers, Schneier's work does not read like a dry paper for a scientific journal. His writing is very enjoyable (though the jokes are overdone at times) and his explanations are almost always lucid.

Breaking a plate is a good example of a one-way function. It is easy to smash a plate into a thousand tiny pieces. However, it's not easy to put all those tiny pieces back together into a plate. [...]

So, what good are one-way functions? We can't use them for encryption as is. A message encrypted with the one-way function isn't useful; no one could decrypt it. (Exercise: Write a message of a plate, smash the plate into bits, and then give the bits to a friend. Ask your friend to read the message. Observe how impressed he is with the one-way function.) For public-key cryptography, we need something else.

Generally, the book covers four main subjects: protocols, algorithms, source code (in C), and politics. As the title indicates, the book is intended to people who actually wish to apply cryptographic methods to their programs, and so the theoretical discussions and mostly at introductory level - sufficient to make you understand how an algorithm works and what are its benefits and potential weaknesses, but without elaborate mathematical proofs, for example.

Part I of the book, "Cryptographic Protocols", includes five chapters: building blocks, basic protocols (like key exchange and authentication), intermediate protocols (timestamping, fair coin flips, key escrew, etc.), advanced (zero-knowledge proofs, simultaneous contract signing, digital certified mail, etc.) and esoteric ones (like secure elections and anonymous message broadcast).

Part II, "Cryptographic Techniques", deals with such issues as key length, key management, and methods of employing algorithms. The longest section, Part III, spans 13 chapters -- "Cryptographic Algorithms". The algorithms covered include DES and its variants,Skipjack, Lucifer, LOKI, RC2, RC4, RC5 (that's the cow in your tray-bin!), IDEA Blowfish, RSA and many others. The greatest detail is given to the venerable old DES, but the information about other protocols (over 50 in all, including blockDES, but the information about other protocols (over 50 in all, including block ciphers, stream ciphers, random-sequence generators, one-way hash functions, public key algorithms, and more) is sufficiently detailed for you to decide which best suites your needs. And if you need more information, an outstandingl$ detailed list of over 1,600 references is included.

As in most texts about cryptography, protocols and algorithms are described using the merry cast of Alice (side A), Bob (side B), Eve the eavesdropper, Mallory the malicious attacker, and their other friends and foes. This makes descriptions much easier, since once you get used to these Dramatis Personae (which happens rather quickly), you immediately know who plays what role in each scene, without wasting time on repeated explanations. Schneier brings those characters to life in numerous examples of the pros and cons of various approaches.

Part IV, "The Real World", deals with two subjects: sample implementations in actual products, and politics, including history and legal issues. The history of cryptography is much longer than that of computer science: from secret codes to invisible inks, encoded messages were here for a very long time indeed. On the other hand, cracking cryptographic codes was among the earliest uses of computers, back in WWII (as anyone familiar with the story of Alan Turing knows).

One section in chapter 25 lists the import and export limitations on cryptography in different places around the globe. The most interesting entry is for my own country, Israel, which (according to Schneier) "has import restrictions, but no one seems to know what they are."

The final section, "Source Code", includes over 50 pages of sources in C for several algorithms: DES, LOKI91, IDEA, GOST, Blowfish, 3-Way, RC5, A5 and SEAL. It looks insane that a book with so many lines of source is not accompanied by a CD; but then you realize that what's insane is not the boo$ but export laws, which allow cryptographic algorithms to be distributed in prin$ -- but not on electronic media. Consider, for example, how Phil Zimmermann's PG$ was legally exported from the US to the rest of the world: the sources were printed in a one-copy book, which was mailed to Europe, scanned in and recompiled.

If you live in the States, you can order a set of 3 floppies directly from Schneier, with sources for most of the algorithms discussed in the book (and more).

Anyone cares to mail me a printout?

Purchase this book at Computer Literay and help Slashdot.

For more information about this book, see the sidebar of http://www.forum2.org/tal/books/crypto.html.

For additional book reviews, please visit http://www.forum2.org/tal/books.

Tal Cohen sent in a 3 part review: The Tao of Programming, The Zen of Programming, and Computer Parables: Enlightenment in the Information Age. All of these were written by Geoffrey James, and while the first book Tao is one that has been around, the other two are interesting reading as well. Click below to find out more. REVIEW: The Tao of Programming, The Zen of Programming and Computer Parables: Enlightenment in the Information Age by Geoffrey James (Tao: InfoBooks, ISBN 0-931-13707-1) (Zen: InfoBooks, ISBN 0-931-13709-8) (Parables: InfoBooks, ISBN 0-931-13713-6) Nutshell
Review: You've probably already read The Tao of Programming -- as an e-text. It's a great book, and fun to re-read every so often; but don't buy the print version just for the illustrations. Do buy it as a gift to a friend, though.

The two sequels, The Zen of Programming and Computer Parables, are less well-known (probably because they were never transcribed and spread over usenet). They're also generally less entertaining, though you'll probably still find them enjoyable.

Rating: Outstanding (8/10), Average (4/10) and Average (4/10) Review by: Tal Cohen

Assigning more people to a programming project does not make it end earlier. There are a many explanations for this; in fact, it is the subject of one of the most important software engineering books, Fredrick Brooks's The Mythical Man Month. But experienced programmers don't need research results to tell them about this. For them, it is a fact of life -- knowledge earned by working on software projects for years. So many programmers appreciate Geoffrey James's simple way of presenting this fact in a very short story:

A manager went to the master programmer and showed him the requirements document for a new application. The manager asked the master: "How long will it take to design this system if I assign five programmers to it?"

"It will take one year," said the master promptly.

"But we need this system immediately or even sooner! How long will it take if I assign ten programmers to it?"

The master programmer frowned. "In that case, it will take two years."

"And what if I assign a hundred programmers to it?"

The master programmer shrugged. "Then the design will never be completed," he said.

The simple, humoristic representation of experienced software developers as "masters" and inexperienced ones as "apprentices", the characterization of managers as unintelligent, sometimes plain stupid people, combined with the simple wisdom of the text is just part of what makes The Tao of Programming such am amusing booklet for programmers. I think many readers will find that they are reminded of the Dilbert comic strips.

Thus spake the master programmer:

"You can demonstrate a program for an executive, but you can't make him computer literate."

The stories are presented with an aura of oriental wisdom; some of them are paraphrases of famous oriental stories. For example, the point of the story in which Grand Master Turing dreams that he is a machine (and wakes up wondering if he is really Turing, or a machine dreaming that it is Turing) will probably be missed by those not familiar with the story about Confucius and the butterfly.

The Tao of Programming contains nine "books" -- each with wisdom about a different area, such as design, coding, maintenance, and so on. All in all, there are about fifty short stories like the two quoted above, and it will probably make a great gift to any programmer. If you haven't read it yet, you should probably buy yourself this gift. In the computer programmers' Humor Hall of Fame, this book resides up there with canons such as the Jargon file ("The Hacker's Dictionary").

The Zen of Programming was published by James a year after The Tao, and it contains numerous short Koan-like stories of the same spirit -- the kind of stories only computer nerds could possibly enjoy. However, much like the stories in the third book Computer Parables: Enlightenment in the Information Age, the stories in The Zen of Programming lack the special, naive magic that made the first book so enjoyable. The stories in these two books don't try just to entertain -- they try to teach a lesson, and often fail miserably. And yet some stories (especially in Computer Parables) do hit the nail on the head. Consider, for example, the following story:

A programmer once built a vast database containing all the literature, facts, figures, and data in the world. The he built an advanced querying system that linked that knowledge together, allowing him to wander through the database at will. Satisfied and pleased, he sat down before his computer to enjoy the fruits of his labor.

After three minutes, the programmer had a headache. After three hours, the programmer felt ill. After three days, the programmer destroyed his database. When asked why, he replied: "That system put the world at my fingertips. I could go anywhere, see anything. Because I was no longer limited by external conditions, I had no excuse for not knowing everything there is to know. I could neither sleep nor eat. All I could do was wander through the database. Now I can rest."

The amazing thing is that this piece was published years before the World Wide Web came to be; it is even more amazing if you consider the fact that it is titled "The Navigator".

Other stories from Computer Parables that had a similar surprising (or should I say sobering?) effect, at least for me, include "The Computer Pornographer" and "The Museum". But apart from these rare gems, the two sequels generally do not stand up to the quality of the first.

To purchase The Tao of Programming, click here to buy it from Amazon. Otherwise, get The Zen of Programming from here, or Computer Parables: Enlightenment in the Information Age from here.

For more information about these books, please visit http://www.forum2.org/tal/books/tao.html.

For additional book reviews, please visit http://www.forum2.org/tal/books.

Tal Cohen sent in a 3 part review: The Tao of Programming, The Zen of Programming, and Computer Parables: Enlightenment in the Information Age. All of these were written by Geoffrey James, and while the first book Tao is one that has been around, the other two are interesting reading as well. Click below to find out more. REVIEW: The Tao of Programming, The Zen of Programming and Computer Parables: Enlightenment in the Information Age by Geoffrey James (Tao: InfoBooks, ISBN 0-931-13707-1) (Zen: InfoBooks, ISBN 0-931-13709-8) (Parables: InfoBooks, ISBN 0-931-13713-6) Nutshell
Review: You've probably already read The Tao of Programming -- as an e-text. It's a great book, and fun to re-read every so often; but don't buy the print version just for the illustrations. Do buy it as a gift to a friend, though.

The two sequels, The Zen of Programming and Computer Parables, are less well-known (probably because they were never transcribed and spread over usenet). They're also generally less entertaining, though you'll probably still find them enjoyable.

Rating: Outstanding (8/10), Average (4/10) and Average (4/10) Review by: Tal Cohen

Assigning more people to a programming project does not make it end earlier. There are a many explanations for this; in fact, it is the subject of one of the most important software engineering books, Fredrick Brooks's The Mythical Man Month. But experienced programmers don't need research results to tell them about this. For them, it is a fact of life -- knowledge earned by working on software projects for years. So many programmers appreciate Geoffrey James's simple way of presenting this fact in a very short story:

A manager went to the master programmer and showed him the requirements document for a new application. The manager asked the master: "How long will it take to design this system if I assign five programmers to it?"

"It will take one year," said the master promptly.

"But we need this system immediately or even sooner! How long will it take if I assign ten programmers to it?"

The master programmer frowned. "In that case, it will take two years."

"And what if I assign a hundred programmers to it?"

The master programmer shrugged. "Then the design will never be completed," he said.

The simple, humoristic representation of experienced software developers as "masters" and inexperienced ones as "apprentices", the characterization of managers as unintelligent, sometimes plain stupid people, combined with the simple wisdom of the text is just part of what makes The Tao of Programming such am amusing booklet for programmers. I think many readers will find that they are reminded of the Dilbert comic strips.

Thus spake the master programmer:

"You can demonstrate a program for an executive, but you can't make him computer literate."

The stories are presented with an aura of oriental wisdom; some of them are paraphrases of famous oriental stories. For example, the point of the story in which Grand Master Turing dreams that he is a machine (and wakes up wondering if he is really Turing, or a machine dreaming that it is Turing) will probably be missed by those not familiar with the story about Confucius and the butterfly.

The Tao of Programming contains nine "books" -- each with wisdom about a different area, such as design, coding, maintenance, and so on. All in all, there are about fifty short stories like the two quoted above, and it will probably make a great gift to any programmer. If you haven't read it yet, you should probably buy yourself this gift. In the computer programmers' Humor Hall of Fame, this book resides up there with canons such as the Jargon file ("The Hacker's Dictionary").

The Zen of Programming was published by James a year after The Tao, and it contains numerous short Koan-like stories of the same spirit -- the kind of stories only computer nerds could possibly enjoy. However, much like the stories in the third book Computer Parables: Enlightenment in the Information Age, the stories in The Zen of Programming lack the special, naive magic that made the first book so enjoyable. The stories in these two books don't try just to entertain -- they try to teach a lesson, and often fail miserably. And yet some stories (especially in Computer Parables) do hit the nail on the head. Consider, for example, the following story:

A programmer once built a vast database containing all the literature, facts, figures, and data in the world. The he built an advanced querying system that linked that knowledge together, allowing him to wander through the database at will. Satisfied and pleased, he sat down before his computer to enjoy the fruits of his labor.

After three minutes, the programmer had a headache. After three hours, the programmer felt ill. After three days, the programmer destroyed his database. When asked why, he replied: "That system put the world at my fingertips. I could go anywhere, see anything. Because I was no longer limited by external conditions, I had no excuse for not knowing everything there is to know. I could neither sleep nor eat. All I could do was wander through the database. Now I can rest."

The amazing thing is that this piece was published years before the World Wide Web came to be; it is even more amazing if you consider the fact that it is titled "The Navigator".

Other stories from Computer Parables that had a similar surprising (or should I say sobering?) effect, at least for me, include "The Computer Pornographer" and "The Museum". But apart from these rare gems, the two sequels generally do not stand up to the quality of the first.

To purchase The Tao of Programming, click here to buy it from Amazon. Otherwise, get The Zen of Programming from here, or Computer Parables: Enlightenment in the Information Age from here.

For more information about these books, please visit http://www.forum2.org/tal/books/tao.html.

For additional book reviews, please visit http://www.forum2.org/tal/books.

Tal Cohen sent in a 3 part review: The Tao of Programming, The Zen of Programming, and Computer Parables: Enlightenment in the Information Age. All of these were written by Geoffrey James, and while the first book Tao is one that has been around, the other two are interesting reading as well. Click below to find out more. REVIEW: The Tao of Programming, The Zen of Programming and Computer Parables: Enlightenment in the Information Age by Geoffrey James (Tao: InfoBooks, ISBN 0-931-13707-1) (Zen: InfoBooks, ISBN 0-931-13709-8) (Parables: InfoBooks, ISBN 0-931-13713-6) Nutshell
Review: You've probably already read The Tao of Programming -- as an e-text. It's a great book, and fun to re-read every so often; but don't buy the print version just for the illustrations. Do buy it as a gift to a friend, though.

The two sequels, The Zen of Programming and Computer Parables, are less well-known (probably because they were never transcribed and spread over usenet). They're also generally less entertaining, though you'll probably still find them enjoyable.

Rating: Outstanding (8/10), Average (4/10) and Average (4/10) Review by: Tal Cohen

Assigning more people to a programming project does not make it end earlier. There are a many explanations for this; in fact, it is the subject of one of the most important software engineering books, Fredrick Brooks's The Mythical Man Month. But experienced programmers don't need research results to tell them about this. For them, it is a fact of life -- knowledge earned by working on software projects for years. So many programmers appreciate Geoffrey James's simple way of presenting this fact in a very short story:

A manager went to the master programmer and showed him the requirements document for a new application. The manager asked the master: "How long will it take to design this system if I assign five programmers to it?"

"It will take one year," said the master promptly.

"But we need this system immediately or even sooner! How long will it take if I assign ten programmers to it?"

The master programmer frowned. "In that case, it will take two years."

"And what if I assign a hundred programmers to it?"

The master programmer shrugged. "Then the design will never be completed," he said.

The simple, humoristic representation of experienced software developers as "masters" and inexperienced ones as "apprentices", the characterization of managers as unintelligent, sometimes plain stupid people, combined with the simple wisdom of the text is just part of what makes The Tao of Programming such am amusing booklet for programmers. I think many readers will find that they are reminded of the Dilbert comic strips.

Thus spake the master programmer:

"You can demonstrate a program for an executive, but you can't make him computer literate."

The stories are presented with an aura of oriental wisdom; some of them are paraphrases of famous oriental stories. For example, the point of the story in which Grand Master Turing dreams that he is a machine (and wakes up wondering if he is really Turing, or a machine dreaming that it is Turing) will probably be missed by those not familiar with the story about Confucius and the butterfly.

The Tao of Programming contains nine "books" -- each with wisdom about a different area, such as design, coding, maintenance, and so on. All in all, there are about fifty short stories like the two quoted above, and it will probably make a great gift to any programmer. If you haven't read it yet, you should probably buy yourself this gift. In the computer programmers' Humor Hall of Fame, this book resides up there with canons such as the Jargon file ("The Hacker's Dictionary").

The Zen of Programming was published by James a year after The Tao, and it contains numerous short Koan-like stories of the same spirit -- the kind of stories only computer nerds could possibly enjoy. However, much like the stories in the third book Computer Parables: Enlightenment in the Information Age, the stories in The Zen of Programming lack the special, naive magic that made the first book so enjoyable. The stories in these two books don't try just to entertain -- they try to teach a lesson, and often fail miserably. And yet some stories (especially in Computer Parables) do hit the nail on the head. Consider, for example, the following story:

A programmer once built a vast database containing all the literature, facts, figures, and data in the world. The he built an advanced querying system that linked that knowledge together, allowing him to wander through the database at will. Satisfied and pleased, he sat down before his computer to enjoy the fruits of his labor.

After three minutes, the programmer had a headache. After three hours, the programmer felt ill. After three days, the programmer destroyed his database. When asked why, he replied: "That system put the world at my fingertips. I could go anywhere, see anything. Because I was no longer limited by external conditions, I had no excuse for not knowing everything there is to know. I could neither sleep nor eat. All I could do was wander through the database. Now I can rest."

The amazing thing is that this piece was published years before the World Wide Web came to be; it is even more amazing if you consider the fact that it is titled "The Navigator".

Other stories from Computer Parables that had a similar surprising (or should I say sobering?) effect, at least for me, include "The Computer Pornographer" and "The Museum". But apart from these rare gems, the two sequels generally do not stand up to the quality of the first.

To purchase The Tao of Programming, click here to buy it from Amazon. Otherwise, get The Zen of Programming from here, or Computer Parables: Enlightenment in the Information Age from here.

For more information about these books, please visit http://www.forum2.org/tal/books/tao.html.

For additional book reviews, please visit http://www.forum2.org/tal/books.

Tal Cohen sent in a 3 part review: The Tao of Programming, The Zen of Programming, and Computer Parables: Enlightenment in the Information Age. All of these were written by Geoffrey James, and while the first book Tao is one that has been around, the other two are interesting reading as well. Click below to find out more. REVIEW: The Tao of Programming, The Zen of Programming and Computer Parables: Enlightenment in the Information Age by Geoffrey James (Tao: InfoBooks, ISBN 0-931-13707-1) (Zen: InfoBooks, ISBN 0-931-13709-8) (Parables: InfoBooks, ISBN 0-931-13713-6) Nutshell
Review: You've probably already read The Tao of Programming -- as an e-text. It's a great book, and fun to re-read every so often; but don't buy the print version just for the illustrations. Do buy it as a gift to a friend, though.

The two sequels, The Zen of Programming and Computer Parables, are less well-known (probably because they were never transcribed and spread over usenet). They're also generally less entertaining, though you'll probably still find them enjoyable.

Rating: Outstanding (8/10), Average (4/10) and Average (4/10) Review by: Tal Cohen

Assigning more people to a programming project does not make it end earlier. There are a many explanations for this; in fact, it is the subject of one of the most important software engineering books, Fredrick Brooks's The Mythical Man Month. But experienced programmers don't need research results to tell them about this. For them, it is a fact of life -- knowledge earned by working on software projects for years. So many programmers appreciate Geoffrey James's simple way of presenting this fact in a very short story:

A manager went to the master programmer and showed him the requirements document for a new application. The manager asked the master: "How long will it take to design this system if I assign five programmers to it?"

"It will take one year," said the master promptly.

"But we need this system immediately or even sooner! How long will it take if I assign ten programmers to it?"

The master programmer frowned. "In that case, it will take two years."

"And what if I assign a hundred programmers to it?"

The master programmer shrugged. "Then the design will never be completed," he said.

The simple, humoristic representation of experienced software developers as "masters" and inexperienced ones as "apprentices", the characterization of managers as unintelligent, sometimes plain stupid people, combined with the simple wisdom of the text is just part of what makes The Tao of Programming such am amusing booklet for programmers. I think many readers will find that they are reminded of the Dilbert comic strips.

Thus spake the master programmer:

"You can demonstrate a program for an executive, but you can't make him computer literate."

The stories are presented with an aura of oriental wisdom; some of them are paraphrases of famous oriental stories. For example, the point of the story in which Grand Master Turing dreams that he is a machine (and wakes up wondering if he is really Turing, or a machine dreaming that it is Turing) will probably be missed by those not familiar with the story about Confucius and the butterfly.

The Tao of Programming contains nine "books" -- each with wisdom about a different area, such as design, coding, maintenance, and so on. All in all, there are about fifty short stories like the two quoted above, and it will probably make a great gift to any programmer. If you haven't read it yet, you should probably buy yourself this gift. In the computer programmers' Humor Hall of Fame, this book resides up there with canons such as the Jargon file ("The Hacker's Dictionary").

The Zen of Programming was published by James a year after The Tao, and it contains numerous short Koan-like stories of the same spirit -- the kind of stories only computer nerds could possibly enjoy. However, much like the stories in the third book Computer Parables: Enlightenment in the Information Age, the stories in The Zen of Programming lack the special, naive magic that made the first book so enjoyable. The stories in these two books don't try just to entertain -- they try to teach a lesson, and often fail miserably. And yet some stories (especially in Computer Parables) do hit the nail on the head. Consider, for example, the following story:

A programmer once built a vast database containing all the literature, facts, figures, and data in the world. The he built an advanced querying system that linked that knowledge together, allowing him to wander through the database at will. Satisfied and pleased, he sat down before his computer to enjoy the fruits of his labor.

After three minutes, the programmer had a headache. After three hours, the programmer felt ill. After three days, the programmer destroyed his database. When asked why, he replied: "That system put the world at my fingertips. I could go anywhere, see anything. Because I was no longer limited by external conditions, I had no excuse for not knowing everything there is to know. I could neither sleep nor eat. All I could do was wander through the database. Now I can rest."

The amazing thing is that this piece was published years before the World Wide Web came to be; it is even more amazing if you consider the fact that it is titled "The Navigator".

Other stories from Computer Parables that had a similar surprising (or should I say sobering?) effect, at least for me, include "The Computer Pornographer" and "The Museum". But apart from these rare gems, the two sequels generally do not stand up to the quality of the first.

To purchase The Tao of Programming, click here to buy it from Amazon. Otherwise, get The Zen of Programming from here, or Computer Parables: Enlightenment in the Information Age from here.

For more information about these books, please visit http://www.forum2.org/tal/books/tao.html.

For additional book reviews, please visit http://www.forum2.org/tal/books.

Tal Cohen sent in a 3 part review: The Tao of Programming, The Zen of Programming, and Computer Parables: Enlightenment in the Information Age. All of these were written by Geoffrey James, and while the first book Tao is one that has been around, the other two are interesting reading as well. Click below to find out more. REVIEW: The Tao of Programming, The Zen of Programming and Computer Parables: Enlightenment in the Information Age by Geoffrey James (Tao: InfoBooks, ISBN 0-931-13707-1) (Zen: InfoBooks, ISBN 0-931-13709-8) (Parables: InfoBooks, ISBN 0-931-13713-6) Nutshell
Review: You've probably already read The Tao of Programming -- as an e-text. It's a great book, and fun to re-read every so often; but don't buy the print version just for the illustrations. Do buy it as a gift to a friend, though.

The two sequels, The Zen of Programming and Computer Parables, are less well-known (probably because they were never transcribed and spread over usenet). They're also generally less entertaining, though you'll probably still find them enjoyable.

Rating: Outstanding (8/10), Average (4/10) and Average (4/10) Review by: Tal Cohen

Assigning more people to a programming project does not make it end earlier. There are a many explanations for this; in fact, it is the subject of one of the most important software engineering books, Fredrick Brooks's The Mythical Man Month. But experienced programmers don't need research results to tell them about this. For them, it is a fact of life -- knowledge earned by working on software projects for years. So many programmers appreciate Geoffrey James's simple way of presenting this fact in a very short story:

A manager went to the master programmer and showed him the requirements document for a new application. The manager asked the master: "How long will it take to design this system if I assign five programmers to it?"

"It will take one year," said the master promptly.

"But we need this system immediately or even sooner! How long will it take if I assign ten programmers to it?"

The master programmer frowned. "In that case, it will take two years."

"And what if I assign a hundred programmers to it?"

The master programmer shrugged. "Then the design will never be completed," he said.

The simple, humoristic representation of experienced software developers as "masters" and inexperienced ones as "apprentices", the characterization of managers as unintelligent, sometimes plain stupid people, combined with the simple wisdom of the text is just part of what makes The Tao of Programming such am amusing booklet for programmers. I think many readers will find that they are reminded of the Dilbert comic strips.

Thus spake the master programmer:

"You can demonstrate a program for an executive, but you can't make him computer literate."

The stories are presented with an aura of oriental wisdom; some of them are paraphrases of famous oriental stories. For example, the point of the story in which Grand Master Turing dreams that he is a machine (and wakes up wondering if he is really Turing, or a machine dreaming that it is Turing) will probably be missed by those not familiar with the story about Confucius and the butterfly.

The Tao of Programming contains nine "books" -- each with wisdom about a different area, such as design, coding, maintenance, and so on. All in all, there are about fifty short stories like the two quoted above, and it will probably make a great gift to any programmer. If you haven't read it yet, you should probably buy yourself this gift. In the computer programmers' Humor Hall of Fame, this book resides up there with canons such as the Jargon file ("The Hacker's Dictionary").

The Zen of Programming was published by James a year after The Tao, and it contains numerous short Koan-like stories of the same spirit -- the kind of stories only computer nerds could possibly enjoy. However, much like the stories in the third book Computer Parables: Enlightenment in the Information Age, the stories in The Zen of Programming lack the special, naive magic that made the first book so enjoyable. The stories in these two books don't try just to entertain -- they try to teach a lesson, and often fail miserably. And yet some stories (especially in Computer Parables) do hit the nail on the head. Consider, for example, the following story:

A programmer once built a vast database containing all the literature, facts, figures, and data in the world. The he built an advanced querying system that linked that knowledge together, allowing him to wander through the database at will. Satisfied and pleased, he sat down before his computer to enjoy the fruits of his labor.

After three minutes, the programmer had a headache. After three hours, the programmer felt ill. After three days, the programmer destroyed his database. When asked why, he replied: "That system put the world at my fingertips. I could go anywhere, see anything. Because I was no longer limited by external conditions, I had no excuse for not knowing everything there is to know. I could neither sleep nor eat. All I could do was wander through the database. Now I can rest."

The amazing thing is that this piece was published years before the World Wide Web came to be; it is even more amazing if you consider the fact that it is titled "The Navigator".

Other stories from Computer Parables that had a similar surprising (or should I say sobering?) effect, at least for me, include "The Computer Pornographer" and "The Museum". But apart from these rare gems, the two sequels generally do not stand up to the quality of the first.

To purchase The Tao of Programming, click here to buy it from Amazon. Otherwise, get The Zen of Programming from here, or Computer Parables: Enlightenment in the Information Age from here.

For more information about these books, please visit http://www.forum2.org/tal/books/tao.html.

For additional book reviews, please visit http://www.forum2.org/tal/books.

Actually titled Darwin Among the Machines: The Evolution of Global Intelligence, this review of the George Dyson book was sent to us by Tal Cohen. To give a good idea about what the book is exploring, I believe that this quote from Dyson, the author is well suited: "In the game of life and evolution, there are three players at the table: human beings, nature, and machine. I am firmly on the side of nature, but nature, I suspect, is on the side of machines." Touted in intellectual circles, this book examines the convergence of man, nature and machine, and the ramifications as well as examining aspects of it within a well developed historical context. For more, click below. Darwin Among the Machines: The Evolution of Global Intelligence author George B. Dyson pages publisher Helix Books / Addison Wesley rating 4/5 reviewer Tal Cohen ISBN 0-201-40649-7 summary

Could it possibly be that modern communication networks lead us to one of those rare crossroads between really far-fetched science-fiction and reality? In Darwin Among the Machines, George B. Dyson speculates that huge-scale non-human intelligence will inevitably evolve around us. In addition, the book is a refreshing history of both computing and evolution science.

Most scientist today believe that the human mind was never designed; it had evolved, slowly, over millions of generations. The main idea suggested by George Dyson in this book is simple: In the digital universe, too, a conscious mind will evolve naturally, rather than as the result of some design. Artificial Intelligence researches might as well spend their time searching for signs of intelligence on the net rather than try to develop it.

The book begins with a refreshing overview of the history of computing, as well as a brief history of the science of evolution -- with a glance towards the evolution of machines. The history of computing presented in the book is naturally biased towards issues that are relevant to the topic at hand, which is in fact an advantage, since it makes the history seem so much more refreshing.

It is a misconception, based on the stereotype of a Turing machine as executing a prearranged program one step at a time, to assume that Turing believed that any single, explicitly programmed serial process would ever capture human intelligence in mechanical form. Turing knew how many interconnected neurons it took to make a brain, and he knew how many brains it took to form a society that could kindle the spark of language and intelligence into flame.

Surprisingly for a book that deals with artificial life and intelligence, and in which Alan Turing is an important part of the cast, the infamous Turing Test for machine intelligence is hardly mentioned. Turing is not dealt with in the cliched way commonly found in other books on the subject. Rather, we are given a view of Turing as a serious researcher -- and as the first hacker-at-heart:

The IAS memory was based on the Williams tube -- an ordinary cathode-ray tube (CRT) modified to allow data to be read, written, and continuously refreshed as a pattern of charged spots on the phosphor coating inside the tube. [...] You could watch the bits of information dancing on the screen as a computation proceeded, and Turing, who soon joined the Manchester group, was noted for his ability to read numbers directly off the screen, just as he had been able to read binary code directly from teletypewriter tapes as intercepted messages were being sorted out.

Dyson quotes from sources, some surprisingly old, about the implications of the theory of evolution on the world of machines. Newer sources, of course, speak mainly about computers in this context; some of the older quotes in the book, however, date long before the computer was even conceived. In fact, even the book's title is a quote -- it was originally the title of an article published in 1863 by Samuel Butler. Such a substantial amount of text in the book is presented as direct quotes, that at times it creates the illusion that the book is nothing but a very-well done library research job. But do not be fooled: Dyson certainly presents bold new ideas.

Dyson's main claim is that the evolution of a conscious mind from today's technology is inevitable. It is not clear whether this will be a single mind or multiple minds, how smart that mind would be, and even if we will be able to communicate with it. He also clearly suggests that there are forms of intelligence on Earth that we are currently unable to understand.

What mind, if any, will become apprehensive of the great coiling of ideas now under way is not a meaningless question, but it is still too early in the game to expect an answer that is meaningful to us.

While Douglas Hofstadter, in Godel, Escher, Bach, had jokingly suggested an ant colony as a model of a mind, Dyson boldly states that insects have "socially distributed intelligence" (p. 174). He also suggests that human societies might actually form higher-level minds, in which humans take the part of neurons. And just as a neuron cannot possibly comprehend its role in the brain, so we can hardly expect a human the grasp his role in the greater mind that he is part of.

[It] is presumptuous to assume that artificial intelligence will operate on a level, or a time scale, that we are able to comprehend. As we merge toward collective intelligence, our own language and intelligence may be related to a subsidiary role or left behind. When the brass head speaks, there is no guarantee that it will speak in a language that we can understand.

With all the ideas Dyson relates regarding the inevitable appearance of intelligence over modern information networks, one might wonder if this hasn't already occurred. In his book Speaker for the Dead, science-fiction author Orson Scott Card suggested that when such an intelligence will emerge, it will be scared to let us know of its existence, knowing that some people, fearing anything nonhuman, will do their best to terminate it.

To buy this book head over to Amazon.

For more information about the book, please visit http://www.forum2.org/tal/books/darwin.html.

For additional book reviews, please visit http://www.forum2.org/tal/books.

Actually titled Darwin Among the Machines: The Evolution of Global Intelligence, this review of the George Dyson book was sent to us by Tal Cohen. To give a good idea about what the book is exploring, I believe that this quote from Dyson, the author is well suited: "In the game of life and evolution, there are three players at the table: human beings, nature, and machine. I am firmly on the side of nature, but nature, I suspect, is on the side of machines." Touted in intellectual circles, this book examines the convergence of man, nature and machine, and the ramifications as well as examining aspects of it within a well developed historical context. For more, click below. Darwin Among the Machines: The Evolution of Global Intelligence author George B. Dyson pages publisher Helix Books / Addison Wesley rating 4/5 reviewer Tal Cohen ISBN 0-201-40649-7 summary

Could it possibly be that modern communication networks lead us to one of those rare crossroads between really far-fetched science-fiction and reality? In Darwin Among the Machines, George B. Dyson speculates that huge-scale non-human intelligence will inevitably evolve around us. In addition, the book is a refreshing history of both computing and evolution science.

Most scientist today believe that the human mind was never designed; it had evolved, slowly, over millions of generations. The main idea suggested by George Dyson in this book is simple: In the digital universe, too, a conscious mind will evolve naturally, rather than as the result of some design. Artificial Intelligence researches might as well spend their time searching for signs of intelligence on the net rather than try to develop it.

The book begins with a refreshing overview of the history of computing, as well as a brief history of the science of evolution -- with a glance towards the evolution of machines. The history of computing presented in the book is naturally biased towards issues that are relevant to the topic at hand, which is in fact an advantage, since it makes the history seem so much more refreshing.

It is a misconception, based on the stereotype of a Turing machine as executing a prearranged program one step at a time, to assume that Turing believed that any single, explicitly programmed serial process would ever capture human intelligence in mechanical form. Turing knew how many interconnected neurons it took to make a brain, and he knew how many brains it took to form a society that could kindle the spark of language and intelligence into flame.

Surprisingly for a book that deals with artificial life and intelligence, and in which Alan Turing is an important part of the cast, the infamous Turing Test for machine intelligence is hardly mentioned. Turing is not dealt with in the cliched way commonly found in other books on the subject. Rather, we are given a view of Turing as a serious researcher -- and as the first hacker-at-heart:

The IAS memory was based on the Williams tube -- an ordinary cathode-ray tube (CRT) modified to allow data to be read, written, and continuously refreshed as a pattern of charged spots on the phosphor coating inside the tube. [...] You could watch the bits of information dancing on the screen as a computation proceeded, and Turing, who soon joined the Manchester group, was noted for his ability to read numbers directly off the screen, just as he had been able to read binary code directly from teletypewriter tapes as intercepted messages were being sorted out.

Dyson quotes from sources, some surprisingly old, about the implications of the theory of evolution on the world of machines. Newer sources, of course, speak mainly about computers in this context; some of the older quotes in the book, however, date long before the computer was even conceived. In fact, even the book's title is a quote -- it was originally the title of an article published in 1863 by Samuel Butler. Such a substantial amount of text in the book is presented as direct quotes, that at times it creates the illusion that the book is nothing but a very-well done library research job. But do not be fooled: Dyson certainly presents bold new ideas.

Dyson's main claim is that the evolution of a conscious mind from today's technology is inevitable. It is not clear whether this will be a single mind or multiple minds, how smart that mind would be, and even if we will be able to communicate with it. He also clearly suggests that there are forms of intelligence on Earth that we are currently unable to understand.

What mind, if any, will become apprehensive of the great coiling of ideas now under way is not a meaningless question, but it is still too early in the game to expect an answer that is meaningful to us.

While Douglas Hofstadter, in Godel, Escher, Bach, had jokingly suggested an ant colony as a model of a mind, Dyson boldly states that insects have "socially distributed intelligence" (p. 174). He also suggests that human societies might actually form higher-level minds, in which humans take the part of neurons. And just as a neuron cannot possibly comprehend its role in the brain, so we can hardly expect a human the grasp his role in the greater mind that he is part of.

[It] is presumptuous to assume that artificial intelligence will operate on a level, or a time scale, that we are able to comprehend. As we merge toward collective intelligence, our own language and intelligence may be related to a subsidiary role or left behind. When the brass head speaks, there is no guarantee that it will speak in a language that we can understand.

With all the ideas Dyson relates regarding the inevitable appearance of intelligence over modern information networks, one might wonder if this hasn't already occurred. In his book Speaker for the Dead, science-fiction author Orson Scott Card suggested that when such an intelligence will emerge, it will be scared to let us know of its existence, knowing that some people, fearing anything nonhuman, will do their best to terminate it.

To buy this book head over to Amazon.

For more information about the book, please visit http://www.forum2.org/tal/books/darwin.html.

For additional book reviews, please visit http://www.forum2.org/tal/books.

Actually titled Darwin Among the Machines: The Evolution of Global Intelligence, this review of the George Dyson book was sent to us by Tal Cohen. To give a good idea about what the book is exploring, I believe that this quote from Dyson, the author is well suited: "In the game of life and evolution, there are three players at the table: human beings, nature, and machine. I am firmly on the side of nature, but nature, I suspect, is on the side of machines." Touted in intellectual circles, this book examines the convergence of man, nature and machine, and the ramifications as well as examining aspects of it within a well developed historical context. For more, click below. Darwin Among the Machines: The Evolution of Global Intelligence author George B. Dyson pages publisher Helix Books / Addison Wesley rating 4/5 reviewer Tal Cohen ISBN 0-201-40649-7 summary

Could it possibly be that modern communication networks lead us to one of those rare crossroads between really far-fetched science-fiction and reality? In Darwin Among the Machines, George B. Dyson speculates that huge-scale non-human intelligence will inevitably evolve around us. In addition, the book is a refreshing history of both computing and evolution science.

Most scientist today believe that the human mind was never designed; it had evolved, slowly, over millions of generations. The main idea suggested by George Dyson in this book is simple: In the digital universe, too, a conscious mind will evolve naturally, rather than as the result of some design. Artificial Intelligence researches might as well spend their time searching for signs of intelligence on the net rather than try to develop it.

The book begins with a refreshing overview of the history of computing, as well as a brief history of the science of evolution -- with a glance towards the evolution of machines. The history of computing presented in the book is naturally biased towards issues that are relevant to the topic at hand, which is in fact an advantage, since it makes the history seem so much more refreshing.

It is a misconception, based on the stereotype of a Turing machine as executing a prearranged program one step at a time, to assume that Turing believed that any single, explicitly programmed serial process would ever capture human intelligence in mechanical form. Turing knew how many interconnected neurons it took to make a brain, and he knew how many brains it took to form a society that could kindle the spark of language and intelligence into flame.

Surprisingly for a book that deals with artificial life and intelligence, and in which Alan Turing is an important part of the cast, the infamous Turing Test for machine intelligence is hardly mentioned. Turing is not dealt with in the cliched way commonly found in other books on the subject. Rather, we are given a view of Turing as a serious researcher -- and as the first hacker-at-heart:

The IAS memory was based on the Williams tube -- an ordinary cathode-ray tube (CRT) modified to allow data to be read, written, and continuously refreshed as a pattern of charged spots on the phosphor coating inside the tube. [...] You could watch the bits of information dancing on the screen as a computation proceeded, and Turing, who soon joined the Manchester group, was noted for his ability to read numbers directly off the screen, just as he had been able to read binary code directly from teletypewriter tapes as intercepted messages were being sorted out.

Dyson quotes from sources, some surprisingly old, about the implications of the theory of evolution on the world of machines. Newer sources, of course, speak mainly about computers in this context; some of the older quotes in the book, however, date long before the computer was even conceived. In fact, even the book's title is a quote -- it was originally the title of an article published in 1863 by Samuel Butler. Such a substantial amount of text in the book is presented as direct quotes, that at times it creates the illusion that the book is nothing but a very-well done library research job. But do not be fooled: Dyson certainly presents bold new ideas.

Dyson's main claim is that the evolution of a conscious mind from today's technology is inevitable. It is not clear whether this will be a single mind or multiple minds, how smart that mind would be, and even if we will be able to communicate with it. He also clearly suggests that there are forms of intelligence on Earth that we are currently unable to understand.

What mind, if any, will become apprehensive of the great coiling of ideas now under way is not a meaningless question, but it is still too early in the game to expect an answer that is meaningful to us.

While Douglas Hofstadter, in Godel, Escher, Bach, had jokingly suggested an ant colony as a model of a mind, Dyson boldly states that insects have "socially distributed intelligence" (p. 174). He also suggests that human societies might actually form higher-level minds, in which humans take the part of neurons. And just as a neuron cannot possibly comprehend its role in the brain, so we can hardly expect a human the grasp his role in the greater mind that he is part of.

[It] is presumptuous to assume that artificial intelligence will operate on a level, or a time scale, that we are able to comprehend. As we merge toward collective intelligence, our own language and intelligence may be related to a subsidiary role or left behind. When the brass head speaks, there is no guarantee that it will speak in a language that we can understand.

With all the ideas Dyson relates regarding the inevitable appearance of intelligence over modern information networks, one might wonder if this hasn't already occurred. In his book Speaker for the Dead, science-fiction author Orson Scott Card suggested that when such an intelligence will emerge, it will be scared to let us know of its existence, knowing that some people, fearing anything nonhuman, will do their best to terminate it.

To buy this book head over to Amazon.

For more information about the book, please visit http://www.forum2.org/tal/books/darwin.html.

For additional book reviews, please visit http://www.forum2.org/tal/books.

Actually titled Darwin Among the Machines: The Evolution of Global Intelligence, this review of the George Dyson book was sent to us by Tal Cohen. To give a good idea about what the book is exploring, I believe that this quote from Dyson, the author is well suited: "In the game of life and evolution, there are three players at the table: human beings, nature, and machine. I am firmly on the side of nature, but nature, I suspect, is on the side of machines." Touted in intellectual circles, this book examines the convergence of man, nature and machine, and the ramifications as well as examining aspects of it within a well developed historical context. For more, click below. Darwin Among the Machines: The Evolution of Global Intelligence author George B. Dyson pages publisher Helix Books / Addison Wesley rating 4/5 reviewer Tal Cohen ISBN 0-201-40649-7 summary

Could it possibly be that modern communication networks lead us to one of those rare crossroads between really far-fetched science-fiction and reality? In Darwin Among the Machines, George B. Dyson speculates that huge-scale non-human intelligence will inevitably evolve around us. In addition, the book is a refreshing history of both computing and evolution science.

Most scientist today believe that the human mind was never designed; it had evolved, slowly, over millions of generations. The main idea suggested by George Dyson in this book is simple: In the digital universe, too, a conscious mind will evolve naturally, rather than as the result of some design. Artificial Intelligence researches might as well spend their time searching for signs of intelligence on the net rather than try to develop it.

The book begins with a refreshing overview of the history of computing, as well as a brief history of the science of evolution -- with a glance towards the evolution of machines. The history of computing presented in the book is naturally biased towards issues that are relevant to the topic at hand, which is in fact an advantage, since it makes the history seem so much more refreshing.

It is a misconception, based on the stereotype of a Turing machine as executing a prearranged program one step at a time, to assume that Turing believed that any single, explicitly programmed serial process would ever capture human intelligence in mechanical form. Turing knew how many interconnected neurons it took to make a brain, and he knew how many brains it took to form a society that could kindle the spark of language and intelligence into flame.

Surprisingly for a book that deals with artificial life and intelligence, and in which Alan Turing is an important part of the cast, the infamous Turing Test for machine intelligence is hardly mentioned. Turing is not dealt with in the cliched way commonly found in other books on the subject. Rather, we are given a view of Turing as a serious researcher -- and as the first hacker-at-heart:

The IAS memory was based on the Williams tube -- an ordinary cathode-ray tube (CRT) modified to allow data to be read, written, and continuously refreshed as a pattern of charged spots on the phosphor coating inside the tube. [...] You could watch the bits of information dancing on the screen as a computation proceeded, and Turing, who soon joined the Manchester group, was noted for his ability to read numbers directly off the screen, just as he had been able to read binary code directly from teletypewriter tapes as intercepted messages were being sorted out.

Dyson quotes from sources, some surprisingly old, about the implications of the theory of evolution on the world of machines. Newer sources, of course, speak mainly about computers in this context; some of the older quotes in the book, however, date long before the computer was even conceived. In fact, even the book's title is a quote -- it was originally the title of an article published in 1863 by Samuel Butler. Such a substantial amount of text in the book is presented as direct quotes, that at times it creates the illusion that the book is nothing but a very-well done library research job. But do not be fooled: Dyson certainly presents bold new ideas.

Dyson's main claim is that the evolution of a conscious mind from today's technology is inevitable. It is not clear whether this will be a single mind or multiple minds, how smart that mind would be, and even if we will be able to communicate with it. He also clearly suggests that there are forms of intelligence on Earth that we are currently unable to understand.

What mind, if any, will become apprehensive of the great coiling of ideas now under way is not a meaningless question, but it is still too early in the game to expect an answer that is meaningful to us.

While Douglas Hofstadter, in Godel, Escher, Bach, had jokingly suggested an ant colony as a model of a mind, Dyson boldly states that insects have "socially distributed intelligence" (p. 174). He also suggests that human societies might actually form higher-level minds, in which humans take the part of neurons. And just as a neuron cannot possibly comprehend its role in the brain, so we can hardly expect a human the grasp his role in the greater mind that he is part of.

[It] is presumptuous to assume that artificial intelligence will operate on a level, or a time scale, that we are able to comprehend. As we merge toward collective intelligence, our own language and intelligence may be related to a subsidiary role or left behind. When the brass head speaks, there is no guarantee that it will speak in a language that we can understand.

With all the ideas Dyson relates regarding the inevitable appearance of intelligence over modern information networks, one might wonder if this hasn't already occurred. In his book Speaker for the Dead, science-fiction author Orson Scott Card suggested that when such an intelligence will emerge, it will be scared to let us know of its existence, knowing that some people, fearing anything nonhuman, will do their best to terminate it.

To buy this book head over to Amazon.

For more information about the book, please visit http://www.forum2.org/tal/books/darwin.html.

For additional book reviews, please visit http://www.forum2.org/tal/books.

Actually titled Darwin Among the Machines: The Evolution of Global Intelligence, this review of the George Dyson book was sent to us by Tal Cohen. To give a good idea about what the book is exploring, I believe that this quote from Dyson, the author is well suited: "In the game of life and evolution, there are three players at the table: human beings, nature, and machine. I am firmly on the side of nature, but nature, I suspect, is on the side of machines." Touted in intellectual circles, this book examines the convergence of man, nature and machine, and the ramifications as well as examining aspects of it within a well developed historical context. For more, click below. Darwin Among the Machines: The Evolution of Global Intelligence author George B. Dyson pages publisher Helix Books / Addison Wesley rating 4/5 reviewer Tal Cohen ISBN 0-201-40649-7 summary

Could it possibly be that modern communication networks lead us to one of those rare crossroads between really far-fetched science-fiction and reality? In Darwin Among the Machines, George B. Dyson speculates that huge-scale non-human intelligence will inevitably evolve around us. In addition, the book is a refreshing history of both computing and evolution science.

Most scientist today believe that the human mind was never designed; it had evolved, slowly, over millions of generations. The main idea suggested by George Dyson in this book is simple: In the digital universe, too, a conscious mind will evolve naturally, rather than as the result of some design. Artificial Intelligence researches might as well spend their time searching for signs of intelligence on the net rather than try to develop it.

The book begins with a refreshing overview of the history of computing, as well as a brief history of the science of evolution -- with a glance towards the evolution of machines. The history of computing presented in the book is naturally biased towards issues that are relevant to the topic at hand, which is in fact an advantage, since it makes the history seem so much more refreshing.

It is a misconception, based on the stereotype of a Turing machine as executing a prearranged program one step at a time, to assume that Turing believed that any single, explicitly programmed serial process would ever capture human intelligence in mechanical form. Turing knew how many interconnected neurons it took to make a brain, and he knew how many brains it took to form a society that could kindle the spark of language and intelligence into flame.

Surprisingly for a book that deals with artificial life and intelligence, and in which Alan Turing is an important part of the cast, the infamous Turing Test for machine intelligence is hardly mentioned. Turing is not dealt with in the cliched way commonly found in other books on the subject. Rather, we are given a view of Turing as a serious researcher -- and as the first hacker-at-heart:

The IAS memory was based on the Williams tube -- an ordinary cathode-ray tube (CRT) modified to allow data to be read, written, and continuously refreshed as a pattern of charged spots on the phosphor coating inside the tube. [...] You could watch the bits of information dancing on the screen as a computation proceeded, and Turing, who soon joined the Manchester group, was noted for his ability to read numbers directly off the screen, just as he had been able to read binary code directly from teletypewriter tapes as intercepted messages were being sorted out.

Dyson quotes from sources, some surprisingly old, about the implications of the theory of evolution on the world of machines. Newer sources, of course, speak mainly about computers in this context; some of the older quotes in the book, however, date long before the computer was even conceived. In fact, even the book's title is a quote -- it was originally the title of an article published in 1863 by Samuel Butler. Such a substantial amount of text in the book is presented as direct quotes, that at times it creates the illusion that the book is nothing but a very-well done library research job. But do not be fooled: Dyson certainly presents bold new ideas.

Dyson's main claim is that the evolution of a conscious mind from today's technology is inevitable. It is not clear whether this will be a single mind or multiple minds, how smart that mind would be, and even if we will be able to communicate with it. He also clearly suggests that there are forms of intelligence on Earth that we are currently unable to understand.

What mind, if any, will become apprehensive of the great coiling of ideas now under way is not a meaningless question, but it is still too early in the game to expect an answer that is meaningful to us.

While Douglas Hofstadter, in Godel, Escher, Bach, had jokingly suggested an ant colony as a model of a mind, Dyson boldly states that insects have "socially distributed intelligence" (p. 174). He also suggests that human societies might actually form higher-level minds, in which humans take the part of neurons. And just as a neuron cannot possibly comprehend its role in the brain, so we can hardly expect a human the grasp his role in the greater mind that he is part of.

[It] is presumptuous to assume that artificial intelligence will operate on a level, or a time scale, that we are able to comprehend. As we merge toward collective intelligence, our own language and intelligence may be related to a subsidiary role or left behind. When the brass head speaks, there is no guarantee that it will speak in a language that we can understand.

With all the ideas Dyson relates regarding the inevitable appearance of intelligence over modern information networks, one might wonder if this hasn't already occurred. In his book Speaker for the Dead, science-fiction author Orson Scott Card suggested that when such an intelligence will emerge, it will be scared to let us know of its existence, knowing that some people, fearing anything nonhuman, will do their best to terminate it.

To buy this book head over to Amazon.

For more information about the book, please visit http://www.forum2.org/tal/books/darwin.html.

For additional book reviews, please visit http://www.forum2.org/tal/books.