ISBNs suck as identifiers for digital books, especially digital books that are free. There are two problems.
Problem number one is that they cost money. Let's say someone writes up a really nice manual documenting some open-source software. He wants the manual to be free, just like the software. But now if he wants an ISBN, he has to pay money to get the ISBN, which means expending dollars on a book that is not going to be bringing in any dollars. The fact that ISBNs cost money is out of step with the fact that we have this thing called the World Wide Web, which is basically a huge machine for letting people do publishing without the per-copy costs that are associated with print publishing.
The other problem is that ISBNs are supposed to uniquely identify an edition of the book. This makes sense for traditional print publishing, where the economics of production forced people to make discrete editions widely spaced in time. It makes no sense for print on demand or for pure digital publishing. I've written some CC-licensed textbooks. When someone emails me to let me know about a typo or a factual error, I fix it right away in the digital version, and I usually update the print-on-demand version within about 6 months. No way am I going to assign a different ISBN every 6 months.
We can say that ISBNs are for printed books, not for ephemeral web pages, but that doesn't really work. The two overlap. My textbooks exist simultaneously as web pages, pdf files, and printed books. Amazon sells a book for the kindle using one ISBN, assigning a different ISBN to the printed version. Print-on-demand books share some characteristics with printed books (e.g., they're physical objects) and some with the web (can be updated continuously).
By the way, why do you think library catalogs don't show ISBNs? It's because ISBNs are meant as commercial tools, like the barcode on a box of cereal. If google finds ISBNs useful for other purposes than selling copies of books, it's probably because google is trying to deal with a massive number of books using a minimum amount of human labor.
If you want to prove that all the digits are correct, you only have to check a few things:
1. There is a sound mathematical proof that the algorithm used in fact does generate the digits of pi, and
2. The algorithm was coded correctly. This should be even easier to check, though likely more tedious.
No, that isn't practical or sufficient, and it's not how they actually did it. Proving nontrivial pieces of software to be correct is basically impossible, and really you'd also need to prove that the compiler was correct, the CPU was correct, etc. -- in fact, computation of pi is often used as a test of new hardware.
Some typical methods that give good confidence in such a calculation:
1. You're calculating pi using a series approximation. These series approximations typically come in families, with different series in the same family being implementable with the same algorithms and having similar performance. You calculate it using two different series, and verify that both series give the same result.
2. You verify an identity. A typical example (which would not be practical for the actual calculation described in the article) would be to calculate tan(pi/4) using the Taylor series for tan(x), and verify that it equals 1.
3. There are algorithms that can compute the nth digit without computing digits 1 through n-1. You can check selected digits against that.
They actually used method 3 plus some other methods.
Your post sounds kind of hostile and defensive. I'm just interested in discussing the free books that are out there, and seeing if there are good free books that I don't know about. Let's put it this way. Suppose you're hired to teach first-semester calculus for fall 2010, and you have complete freedom to choose any book you like. Would you choose a free book? If so, which one?
I can only comment on the situation in my own state, which is California. The kind of heavy regulation you're describing is more a feature of California K-8 education. High school is a lot looser. Also, California has a Free Digital Textbook Initiative, which is designed to help free high school texts get adopted in public high schools. But although the situation is not always as dire as you make out, it's definitely true that private high schools are much more open to free textbooks than public ones.
When it comes to college level stuff, mathematics has more free books available online than any other discipline.
Yet, most universities use either James Stewart or one other book for calculus.
There are a number of free calc textbooks out there. However, I'm not aware of a free calc textbook that would be likely to be tempting as a choice for department-wide adoption at a big, bureaucratic school. A book can be good without being a viable candidate for a department to choose. They're not going to give extra brownie points for the fact that the book is free. They want something professionally laid out, with lots of exercises, and good ancillary materials. Do you know of an intro calc book that you think is really a good candidate? I like Keisler's Elementary Calculus: An Approach Using Infinitesimals, and it is a professionally put together book, but I suspect that the use of infinitesimals is the kiss of death in the eyes of most profs. Gilbert Strang's book appears more mainstream in its approach, but it's only available in a horrible eye-straining low-resolution scan. Both Strang and Keisler are only free as in beer, not free as in speech, so they represent dead ends in terms of the free-information ecosystem. There are some free-as-in-speech intro calc books out there, but most of the ones I know of probably deviate too much from the standard order of topics to be likely to be widely adopted.
It may be unethical to have students use a text book written by you, but it happens a fair bit.
It's only unethical if the professor adopts his own book and also doesn't make the book available for free to his own students. I teach using my own physics text, but it's free online.
Rather than re-invent the wheel, he could also have a look at South Africa's free science and math textbooks: http://www.fhsst.org/
My books predate theirs by several years, and mine are college-level, while theirs are for high school. I think what FHSST is doing is great, and since the two books are under compatible copyleft licenses, we're both contributing to the same free-information ecosystem. Even if the books had been at the same level, I don't think that having more than one textbook on the same subject constitutes reinventing the wheel. Different books treat the same subject differently, and individual professors will have their own criteria for picking books. If commercial publishers have dozens of non-free options to offer on a particular subject, I think it's healthy for there to be more than one free book as well; otherwise a professor who doesn't like the one free book will have no choice but to use a non-free book.
Does anyone know of any pre-1923 (i.e. out of copyright) series of educational books for early education that could serve as the foundation for some "open source" textbooks?
Thompson's Calculus Made Easy is PD, and it's quite a good book IMO. Actually 1923 isn't really the dividing line. Nearly all books published in the 20's, 30's, and 40's are PD now. If books from that era didn't get their copyrights renewed after an initial 28 years (and only a tiny percentage did), then they went PD. You can check whether a book's copyright was renewed using links from this page.
It's very easy to find old PD algebra books, spellers, etc. In most cases, they're not anything that 99% of today's teachers would consider using.
In my opinion, the NY Times article focuses mostly on aspects of the free textbook movement that have been the least successful. It focuses on K-12, but actually there are very few high-quality, free K-12 textbooks; most of the high-quality, free texts are at the college level, and especially at the graduate level. This is probably partly because the opportunities for profit in a non-free book get thinner and thinner as you go to higher and higher levels, and also partly because most states' public K-12 systems have very restrictive requirements for textbooks, which make it virtually impossible for the schools to adopt free books. I've written some free physics textbooks, which are college level. I do have a bunch of high school adoptions, but those are almost 100% from private high schools, mainly Catholic schools.
Another thing the article focuses on is group-organized efforts such as Curriki and CK-12. If you look at the free textbooks that are out there (see my sig), the vast majority are purely individual efforts.
I have a weird hobby of collecting pre-1950 textbooks, and frankly I think kids learned "more" back then from their textbooks than they do today.
I share your idiosyncrasy. I have a fairly big collection of old physics textbooks, mostly college-level books from the 20's and 30's. Actually IMO they're far worse than today's textbooks. They have a lot of detailed diagrams of devices like butter churns and arc lights, but the underlying concepts are very poorly developed.
The Ars Technica article links to the paper on the Nature web site, where it's paywalled. The authors have posted the article here, where you can access it without paying.
The Ars summary is also inaccurate.
First off, this paper does not "topple Heisenberg's uncertainty principle." If you look at the paper, equation (1) is the Heisenberg uncertainty relation, while equation (2) is a similar, but different, uncertainty relation. The paper claims to demonstrate a violation of (2), not (1). Since (1) was proved mathematically 80 years ago based on standard quantum mechanics, disproving it would require either detecting an error in the original proof (which the authors don't claim to have done) or doing the disproof using some foundational theory other than standard quantum mechanics (which the authors didn't do).
And in my opinion the authors' depiction of their own result is an extreme over-selling of what it really says. On p. 1 of the paper, they interpret equation (2) in terms of a game in which Bob tries to predict something as accurately as possible -- more accurately than permitted by (2). To accomplish this, they have Bob store his prediction in a quantum memory device. The quantum memory device is in a superposition of states, sort of like Schrodinger's cat. The memory is partially in a state where it makes prediction P, and partially in a state where it makes a different prediction Q. Only when you read out the memory later do you force the memory to collapse its wavefunction into either state P or state Q. It seems to me that by any reasonable standard, this is not really a prediction at all. If you redefine "prediction" to mean something this weak, then you get all kinds of silly possibilities. For instance, I could entangle my quantum memory's wavefunction with the quantum state of a uranium nucleus, in such a way that I "predict" when the nucleus will decay. Well, I haven't really found a technology for predicting when the nucleus will decay; all I've done is weaken the definition of "predict."
The article leaves me feeling not very enlightened.
When the Chernobyl disaster happened, two changes were made simultaneously to the local ecosystem: (1) There was radioactive crud spread around. (2) Humans left the area.
It's fairly obvious that #2 should have a huge positive effect on many species. Having humans turn habitat into a city, and then drive around it incessantly in cars, is the worst thing that can possibly happen to any plant or animal's habitat. (Of course there might be a few exceptions, like mice and cockroaches, or plants that benefit from artificial irrigation, or certain plant species that tend to thrive in disturbed areas like road cuts.)
Effect #1, radiation, could be either positive or negative. A wide variety of data shows that low levels of radiation are beneficial to almost all living things, until you get to a certain dose at which the net effect starts to become negative. This is called radiation hormesis. Surprisingly, there is even a radiation hormesis effect on reproduction. That is, organisms like mice and fish actually produce more, healthier offspring when they're exposed to small doses of radiation. Radiation doses at Chernobyl are not uniform. You can look at contour maps that show how much radiation there is in different places. The dose is much, much higher when you're closer to the ruined plant. So roughly speaking, I'd imagine that some organisms a little farther out from the site would benefit from hormesis, while others closer in would be harmed. In any case, I would expect #1, radiation, to be a much, much weaker effect than #2, removing people.
The article makes it sound like they just tried to do surveys and evaluate biodiversity, and different people are getting different answers about whether biodiversity is up or down. Seems to me that this tells us absolutely nothing. If biodiversity has increased, it could be because effect #2 is extremely powerful, outweighing significant harm from #1. Or it could be that both #1 and #2 are positive (you get a net hormesis effect). If biodiversity is down, I'm still not sure it tells me anything. Maybe it just means that #2 is negative, for some counterintuitive reason. After all, you kick an ecosystem like crazy (by evacuating all the people), and it's not necessarily easy to tell what will happen. Maybe eliminating humans made it a better environment for predators, which made it a worse environment for prey animals. Maybe eliminating humans allowed a small number of weed species to take over instead of a larger number of ornamental and cultivated plants.
The built-in PDF feature isn't available on the linux version yet.
Some questions that I had that weren't answered by TFA:
Is the PDF renderer fully open source and available under the same license as everything else, so that it can be included in nonproprietary builds of Chromium?
TFA says: "The plug-in doesn't do everything that the Adobe Reader does. It can't handle, for instance, certain embedded media[...]" This is probably a good thing, IMO. The $40,000 question is whether it supports javascript embedded in PDFs, which is the huge security nightmare in Adobe Reader. If it does support it, I hope it's turned off by default. Since I run linux, I can't test this. Can any slashdotters try it and find out?
Same question as #2 for embedded flash. I assume they haven't implemented it, hope they never do.
What is the patent situation with the implemented and nonimplemented "embedded media," and how does this affect fully nonproprietary builds of Chromium?
This is supposed to open up participation by anonymous and new editors so that they can work on a small number of highly controversial articles. It might work, for those articles. But there is a broader problem that it won't address, which is that when a newbie edits *any* article on WP, they are extremely likely to get slapped in the face by having their edits immediately reverted without any explanation. I started working on WP articles in 2002, did a lot of editing until 2006, and finally gave up and munged the password to my account so I wouldn't be tempted to get heavily into it again. Somewhere between 2002 and 2006, the whole experience changed. These days, WP belongs to people who keep watch-lists of articles that they want to defend. The type of person who is successful at this game is totally obsessed with making sure that a particular paragraph in the article on shoe polish remains the way it is. Since I only edit anonymously now, I see the same experience as a newbie, and it ain't pretty. If you add a citation to a source, people will revert you because they assume the link is spam. If you clean up redundant text in an article, people revert you because they were in love with the sentence they wrote, and want it to stay in the article. Recently I added a couple of sentences to a WWII-era biographical article in which I referred to the Nazi party, and someone's bot reverted it because "Nazi" was a keyword that it was programmed to assume indicated vandalism.
I thought that the event horizon of a black hole was caused by the immense gravity of the main body. Just an area of space around the black hole where light would be unable to maintain enough momentum to escape the gravitational pull of the singularity. I don't even want to try understanding the calculations that this theory was derived from. If you were able to remove the event horizon, would that not mean that you would be destroying the singularity itself?
Cyber0ne and internic have done a good job of explaining what happens with a standard Schwarzschild black hole, but I don't think that really addresses what Tarchan was asking about, which is what it would mean to have a naked singularity (one without an event horizon).
The only naked singularity that we actually can verify the existence of is the big bang. It was a singularity, but a different type of singularity than a black hole singularity.
So you can see already that singularities come in more than one flavor. Just because a Schwarzschild black hole solution has a singularity surrounded by an event horizon, that doesn't mean that all singularities do.
The kind of naked singularity they're describing in this paper is one that has a whole bunch of angular momentum and/or charge. This changes the properties of the space around the singularity, due to effects like frame dragging. It's well established that effects like these can lead to a naked singularity. What's much more uncertain is whether naked singularities can arise from any realistic initial conditions in our universe; this is what the cosmic censorship hypothesis says can't happen. The calculations in the paper describe such a process, which would be a counterexample to cosmic censorship. But they use various approximations, and nobody knows whether those approximations are valid.
I once read a bit about black holes, and one of the things I read was: a black hole doesn't necessarily have to be very dense. It can also be sparse (and the larger, the sparser it can be). For example, if you'd take a lot of stars and planets, and put them together (but not too close together), then at one point if you make this large enough, it'll also be a black hole: there appears an event horizon around all this matter. But inside of it are still stars with gaps between them, maybe some planets orbiting around them,... So now I wonder, if the above is true: can someone live inside that? Would there be any noticeable difference between being inside of that, and the other side (the outside) of this event horizon?
You do understand that he was just saying there is no way to actually formalize a singularity, right? That there really isn't any chance socks will come out of a singularity.
I don't think you're understanding his point correctly. Singularities can be formalized mathematically. That's not the issue. The issue is the inability to use the theory to make predictions, when there are naked singularities. What he's saying is that if we observed a naked singularity, it would not violate the field equations of GR if any unpredictable thing whatsoever came flying out. In fact, actual, literal socks do come flying out of naked singularities. I'm wearing a pair of cotton socks right now, and they came flying out of a naked singularity known as the big bang. The question posed by the cosmic censorship hypothesis is whether other naked singularities could arise in our universe from realistic initial conditions.
The title of the paper is "Destroying black holes with test bodies," and the language about "destroying" black holes is echoed in both the arxiv blog summary and the/. summary. This may be somewhat misleading. They're actually talking about processes that would strip away the event horizon, leaving behind a naked singularity. The black hole wouldn't have been "destroyed," but just changed into a different form. The authors themselves put the word "destroying" in quotes in the paper.
The paper doesn't settle this one way or the other. It says shows that if you use a certain set of approximations, the result is that the event horizon can go away. However, there is no particular reason to believe that the approximation is correct.
The real issue here isn't whether a black hole can actually be transformed this way, it's the question of whether cosmic censorship holds. If cosmic censorship fails, then general relativity is fundamentally flawed as a classical field theory, because it fails to make predictions. John Earman's famous way of expressing this is that anything could come out of a naked singularity: lost socks, green slime, even horrible things like Nixon's "Checkers" speech or Japanese monster-movie creatures.
This "story" is an ad, with promotional language in the slashdot summary like "available for a limited period." The OS isn't open source. Looks like someone knows how to game the firehose.
Maybe teach creationism, ID AND evolution in school... teach them as the three most widely-accepted ideas on how the world started and push them forward as all *theories* and there is no scientific proof (there is evidence for some, but that is not conclusive proof) for any of it yet?
"Theory" in science doesn't mean the same thing as "theory" in common speech. In everyday speech, "theory" means "what someone thinks." In science, it means something that is capable of making testable predictions, and that has made correct predictions in all the cases where the theory is applicable. For example, Newton's law of gravity is a scientific theory. Although we know it's not true in any absolute sense (because it's only an approximation to general relativity), we know that it is accurate to within certain bounds, under certain conditions.
Creationism and intelligent design are not scientific theories in this sense. They don't testable predictions.
One of the favorite lines of creationists is "it's only a theory." If they mean that evolution is only a (scientific) theory, then they're saying that evolution is totally solid. If they're saying that creationism is only an (alternative) (scientific) theory, then they don't understand what a scientific theory is.
...and the big [bang] sounds plausible considering the expansion rate of the universe. Is that how it happened ultimately? No freaking clue and I think we fight and evangelize about it too much (myself included at times).
Here it sounds like you just don't have enough scientific knowledge to evaluate the evidence correctly. The current rate of expansion of the universe is not the only evidence for the big bang theory. Within the last 15 years, cosmology has become an exact science. There are extremely tight observational constraints. In addition, one of the things Stephen Hawking built his early career on was proving certain singularity theorems. One of those singularity theorems says that given what we currently observe about the universe, general relativity predicts that there *has* to have been a big bang.
One of the most common things that laypeople misundertand about science is that they think scientists know about things they don't know about, and don't know about things that they do know about. The big bang falls in the latter category. Just because you don't know enough about the evidence to be sure, that doesn't mean there's any doubt remaining among scientists.
The use of the word "controversy" here is taken directly from the creationist playbook. There is "controversy" about whether a big earthquake could cause California to fall off into the Pacific Ocean, but it's only a controversy between two guys sitting in a bar, it's not a controversy among geologists. When creationists say "teach the controversy," they're really asking teachers to present something that's not scientifically controversial as if it were.
Like any flavor of *nix, it was designed from the ground up to live safely in networked, multi-user environments.
This is incorrect. Unix was not designed for security from the ground up. Unix predates the internet by decades. In the 70's and 80's, networking your unix machine meant networking it to other unix machines in the same building. Those other machines were used by people you knew and worked with. If they did something antisocial on the network, you could go knock on their door and politely ask them to stop. For this reason, unix has historically had very poor network security -- by modern standards. For instance, people were still using rlogin well into the 90's -- sending their passwords unencrypted over the network. There was a difference between how unix historically handled network security and how windows handled it, but it was definitely not a matter of ground-up design. Unix adapted more quickly and successfully to the internet. Also, a lot of the security problems on Windows are related to attempts to make it easy to use, whereas unix was never originally aimed at people who had minimal computing skills.
...not very smart. First off, it's silly to equate "smart" to "educated." Smart children of illegal immigrants who pick strawberries don't tend to go to college. Dumb children of business executives tend to go to college and get a degree in something, e.g., education, that doesn't require mastering any speficic, difficult body of knowledge. A college education is a middle-class entitlement in the U.S., like Social Security and Medicare.
The other silly thing about it is that first he tabulates the density of degree holders and finds out that degree holders are more dense where people are more dense. Wow, blinding insight. Then he tries to eliminate the effect of population density using a linear regression, which isn't the right tool for the job. If he wants to eliminate the effect of population density, he should just start with the percentage of the population that has a degree. His linear regression method produces results that obviously don't make much sense, e.g., that Oklahoma City has 544% more people with degrees than you'd expect. (See the note at the bottom of the chart.) Presumably this indicates that not only does every adult in Oklahoma City have a degree, but so do all their children, as do their dogs, cats, and major household appliances.
If what you want is to embed tex in html, you can do it: http://asciimathml.sourceforge.net/ But that doesn't do anything about solving the font problem. You need the fonts, otherwise it can't be rendered. Knuth's Computer Modern fonts were an impressive achievement, but they date back to 1992, and the technology they're built on is obsolete and doesn't fit well with the modern operating systems, or with modern encodings such as unicode. Knuth invented scalable fonts before Adobe reimplemented and commercialized them.
Whatever the merits of this particular disagreement, the term "open source" is definitely getting diluted in the same way that "organic" and "innovative" have been diluted. I went to a symposium in LA last year about the governor's Free Digital Textbook Initiative. There was quite a mix of people there -- teachers, education bureaucrats, open-source software types, authors of free books, people from hardware companies, and people from traditional textbook publishing houses. Everyone was using "open source" like it was magic pixie dust, sprinkling it on everything to make it seem shinier and better. Pearson's rep referred to the consumable workbook it submitted as "free and open-source" -- actually it's just a PDF file that you can download and print, but that you can't redistribute, modify, etc. Houghton Mifflin Harcourt's rep, when questioned about DRM, said that her company was committed to DRM, and envisioned its DRM'd materials being mixed and matched with open-source ones. Both said that they wanted to be service providers (think Red Hat), rather than just content providers (a la Microsoft) -- but, hey, they produce really great content, too. Apple and Dell's reps argued for open formats such as XML.
Part of the reason for the confusion is that people are confused about applying the term to anything other than computer software. When I've mentioned here on slashdot that I was the author of some open-source books, I've sometimes gotten reactions amounting to, "You're an idiot. You don't even know what open source means." This despite the fact that the books are under a GPL-style copyleft license (CC-BY-SA, same as Wikipedia) and their source code (written in a programming language called LaTeX) is openly available and free for redistribution and modification under that license.
It sounds like there's similar confusion here because people aren't distinguishing clearly between the issue of WebM as an open format and the implementation of WebM in open-source software. Who the heck cares whether google's reference implementation is open source, as long as the format is openly defined and usable without paying patent royalties? The first implementations of html by NCSA weren't open source according to the modern meaning of the term, but html was certainly an open format.
No it isn't. Mach is the speed sound travels in a medium (the atmosphere). As there is no atmosphere in orbit, you can't associate a mach speed value to orbital velocities.
Actually the GP was correct. Outer space is not a perfect vacuum, so sound waves can travel in it. The reason you can't hear in outer space is basically an impedance mismatch; the mechanism for turning vibration into sound, and then back into vibration, is extremely inefficient. Next thing to understand is that the speed of sound only depends on temperature, not pressure. Therefore the speed of sound in outer space is not drastically different from the speed of sound in the earth's atmosphere. I believe the temperature of the interplanetary medium in the vicinity of the earth's orbit is on the order of a cold night in Antarctica. So if you want to nitpick about the definition of mach factors, you're nitpicking the wrong variable. You should be nitpicking about temperature, not pressure -- and variations in temperature exist even within the earth's atmosphere, but that doesn't stop us from using mach factors to discuss speeds within the atmosphere.
Slashdot Mirror
ISBNs suck as identifiers for digital books, especially digital books that are free. There are two problems.
Problem number one is that they cost money. Let's say someone writes up a really nice manual documenting some open-source software. He wants the manual to be free, just like the software. But now if he wants an ISBN, he has to pay money to get the ISBN, which means expending dollars on a book that is not going to be bringing in any dollars. The fact that ISBNs cost money is out of step with the fact that we have this thing called the World Wide Web, which is basically a huge machine for letting people do publishing without the per-copy costs that are associated with print publishing.
The other problem is that ISBNs are supposed to uniquely identify an edition of the book. This makes sense for traditional print publishing, where the economics of production forced people to make discrete editions widely spaced in time. It makes no sense for print on demand or for pure digital publishing. I've written some CC-licensed textbooks. When someone emails me to let me know about a typo or a factual error, I fix it right away in the digital version, and I usually update the print-on-demand version within about 6 months. No way am I going to assign a different ISBN every 6 months.
We can say that ISBNs are for printed books, not for ephemeral web pages, but that doesn't really work. The two overlap. My textbooks exist simultaneously as web pages, pdf files, and printed books. Amazon sells a book for the kindle using one ISBN, assigning a different ISBN to the printed version. Print-on-demand books share some characteristics with printed books (e.g., they're physical objects) and some with the web (can be updated continuously).
By the way, why do you think library catalogs don't show ISBNs? It's because ISBNs are meant as commercial tools, like the barcode on a box of cereal. If google finds ISBNs useful for other purposes than selling copies of books, it's probably because google is trying to deal with a massive number of books using a minimum amount of human labor.
No, that isn't practical or sufficient, and it's not how they actually did it. Proving nontrivial pieces of software to be correct is basically impossible, and really you'd also need to prove that the compiler was correct, the CPU was correct, etc. -- in fact, computation of pi is often used as a test of new hardware.
Some typical methods that give good confidence in such a calculation:
1. You're calculating pi using a series approximation. These series approximations typically come in families, with different series in the same family being implementable with the same algorithms and having similar performance. You calculate it using two different series, and verify that both series give the same result.
2. You verify an identity. A typical example (which would not be practical for the actual calculation described in the article) would be to calculate tan(pi/4) using the Taylor series for tan(x), and verify that it equals 1.
3. There are algorithms that can compute the nth digit without computing digits 1 through n-1. You can check selected digits against that.
They actually used method 3 plus some other methods.
Your post sounds kind of hostile and defensive. I'm just interested in discussing the free books that are out there, and seeing if there are good free books that I don't know about. Let's put it this way. Suppose you're hired to teach first-semester calculus for fall 2010, and you have complete freedom to choose any book you like. Would you choose a free book? If so, which one?
I can only comment on the situation in my own state, which is California. The kind of heavy regulation you're describing is more a feature of California K-8 education. High school is a lot looser. Also, California has a Free Digital Textbook Initiative, which is designed to help free high school texts get adopted in public high schools. But although the situation is not always as dire as you make out, it's definitely true that private high schools are much more open to free textbooks than public ones.
There are a number of free calc textbooks out there. However, I'm not aware of a free calc textbook that would be likely to be tempting as a choice for department-wide adoption at a big, bureaucratic school. A book can be good without being a viable candidate for a department to choose. They're not going to give extra brownie points for the fact that the book is free. They want something professionally laid out, with lots of exercises, and good ancillary materials. Do you know of an intro calc book that you think is really a good candidate? I like Keisler's Elementary Calculus: An Approach Using Infinitesimals, and it is a professionally put together book, but I suspect that the use of infinitesimals is the kiss of death in the eyes of most profs. Gilbert Strang's book appears more mainstream in its approach, but it's only available in a horrible eye-straining low-resolution scan. Both Strang and Keisler are only free as in beer, not free as in speech, so they represent dead ends in terms of the free-information ecosystem. There are some free-as-in-speech intro calc books out there, but most of the ones I know of probably deviate too much from the standard order of topics to be likely to be widely adopted.
It's only unethical if the professor adopts his own book and also doesn't make the book available for free to his own students. I teach using my own physics text, but it's free online.
My books predate theirs by several years, and mine are college-level, while theirs are for high school. I think what FHSST is doing is great, and since the two books are under compatible copyleft licenses, we're both contributing to the same free-information ecosystem. Even if the books had been at the same level, I don't think that having more than one textbook on the same subject constitutes reinventing the wheel. Different books treat the same subject differently, and individual professors will have their own criteria for picking books. If commercial publishers have dozens of non-free options to offer on a particular subject, I think it's healthy for there to be more than one free book as well; otherwise a professor who doesn't like the one free book will have no choice but to use a non-free book.
Thompson's Calculus Made Easy is PD, and it's quite a good book IMO. Actually 1923 isn't really the dividing line. Nearly all books published in the 20's, 30's, and 40's are PD now. If books from that era didn't get their copyrights renewed after an initial 28 years (and only a tiny percentage did), then they went PD. You can check whether a book's copyright was renewed using links from this page.
It's very easy to find old PD algebra books, spellers, etc. In most cases, they're not anything that 99% of today's teachers would consider using.
In my opinion, the NY Times article focuses mostly on aspects of the free textbook movement that have been the least successful. It focuses on K-12, but actually there are very few high-quality, free K-12 textbooks; most of the high-quality, free texts are at the college level, and especially at the graduate level. This is probably partly because the opportunities for profit in a non-free book get thinner and thinner as you go to higher and higher levels, and also partly because most states' public K-12 systems have very restrictive requirements for textbooks, which make it virtually impossible for the schools to adopt free books. I've written some free physics textbooks, which are college level. I do have a bunch of high school adoptions, but those are almost 100% from private high schools, mainly Catholic schools.
Another thing the article focuses on is group-organized efforts such as Curriki and CK-12. If you look at the free textbooks that are out there (see my sig), the vast majority are purely individual efforts.
I share your idiosyncrasy. I have a fairly big collection of old physics textbooks, mostly college-level books from the 20's and 30's. Actually IMO they're far worse than today's textbooks. They have a lot of detailed diagrams of devices like butter churns and arc lights, but the underlying concepts are very poorly developed.
The Ars Technica article links to the paper on the Nature web site, where it's paywalled. The authors have posted the article here, where you can access it without paying.
The Ars summary is also inaccurate.
First off, this paper does not "topple Heisenberg's uncertainty principle." If you look at the paper, equation (1) is the Heisenberg uncertainty relation, while equation (2) is a similar, but different, uncertainty relation. The paper claims to demonstrate a violation of (2), not (1). Since (1) was proved mathematically 80 years ago based on standard quantum mechanics, disproving it would require either detecting an error in the original proof (which the authors don't claim to have done) or doing the disproof using some foundational theory other than standard quantum mechanics (which the authors didn't do).
And in my opinion the authors' depiction of their own result is an extreme over-selling of what it really says. On p. 1 of the paper, they interpret equation (2) in terms of a game in which Bob tries to predict something as accurately as possible -- more accurately than permitted by (2). To accomplish this, they have Bob store his prediction in a quantum memory device. The quantum memory device is in a superposition of states, sort of like Schrodinger's cat. The memory is partially in a state where it makes prediction P, and partially in a state where it makes a different prediction Q. Only when you read out the memory later do you force the memory to collapse its wavefunction into either state P or state Q. It seems to me that by any reasonable standard, this is not really a prediction at all. If you redefine "prediction" to mean something this weak, then you get all kinds of silly possibilities. For instance, I could entangle my quantum memory's wavefunction with the quantum state of a uranium nucleus, in such a way that I "predict" when the nucleus will decay. Well, I haven't really found a technology for predicting when the nucleus will decay; all I've done is weaken the definition of "predict."
The article leaves me feeling not very enlightened.
When the Chernobyl disaster happened, two changes were made simultaneously to the local ecosystem: (1) There was radioactive crud spread around. (2) Humans left the area.
It's fairly obvious that #2 should have a huge positive effect on many species. Having humans turn habitat into a city, and then drive around it incessantly in cars, is the worst thing that can possibly happen to any plant or animal's habitat. (Of course there might be a few exceptions, like mice and cockroaches, or plants that benefit from artificial irrigation, or certain plant species that tend to thrive in disturbed areas like road cuts.)
Effect #1, radiation, could be either positive or negative. A wide variety of data shows that low levels of radiation are beneficial to almost all living things, until you get to a certain dose at which the net effect starts to become negative. This is called radiation hormesis. Surprisingly, there is even a radiation hormesis effect on reproduction. That is, organisms like mice and fish actually produce more, healthier offspring when they're exposed to small doses of radiation. Radiation doses at Chernobyl are not uniform. You can look at contour maps that show how much radiation there is in different places. The dose is much, much higher when you're closer to the ruined plant. So roughly speaking, I'd imagine that some organisms a little farther out from the site would benefit from hormesis, while others closer in would be harmed. In any case, I would expect #1, radiation, to be a much, much weaker effect than #2, removing people.
The article makes it sound like they just tried to do surveys and evaluate biodiversity, and different people are getting different answers about whether biodiversity is up or down. Seems to me that this tells us absolutely nothing. If biodiversity has increased, it could be because effect #2 is extremely powerful, outweighing significant harm from #1. Or it could be that both #1 and #2 are positive (you get a net hormesis effect). If biodiversity is down, I'm still not sure it tells me anything. Maybe it just means that #2 is negative, for some counterintuitive reason. After all, you kick an ecosystem like crazy (by evacuating all the people), and it's not necessarily easy to tell what will happen. Maybe eliminating humans made it a better environment for predators, which made it a worse environment for prey animals. Maybe eliminating humans allowed a small number of weed species to take over instead of a larger number of ornamental and cultivated plants.
The built-in PDF feature isn't available on the linux version yet.
Some questions that I had that weren't answered by TFA:
This is supposed to open up participation by anonymous and new editors so that they can work on a small number of highly controversial articles. It might work, for those articles. But there is a broader problem that it won't address, which is that when a newbie edits *any* article on WP, they are extremely likely to get slapped in the face by having their edits immediately reverted without any explanation. I started working on WP articles in 2002, did a lot of editing until 2006, and finally gave up and munged the password to my account so I wouldn't be tempted to get heavily into it again. Somewhere between 2002 and 2006, the whole experience changed. These days, WP belongs to people who keep watch-lists of articles that they want to defend. The type of person who is successful at this game is totally obsessed with making sure that a particular paragraph in the article on shoe polish remains the way it is. Since I only edit anonymously now, I see the same experience as a newbie, and it ain't pretty. If you add a citation to a source, people will revert you because they assume the link is spam. If you clean up redundant text in an article, people revert you because they were in love with the sentence they wrote, and want it to stay in the article. Recently I added a couple of sentences to a WWII-era biographical article in which I referred to the Nazi party, and someone's bot reverted it because "Nazi" was a keyword that it was programmed to assume indicated vandalism.
Cyber0ne and internic have done a good job of explaining what happens with a standard Schwarzschild black hole, but I don't think that really addresses what Tarchan was asking about, which is what it would mean to have a naked singularity (one without an event horizon).
The only naked singularity that we actually can verify the existence of is the big bang. It was a singularity, but a different type of singularity than a black hole singularity.
So you can see already that singularities come in more than one flavor. Just because a Schwarzschild black hole solution has a singularity surrounded by an event horizon, that doesn't mean that all singularities do.
The kind of naked singularity they're describing in this paper is one that has a whole bunch of angular momentum and/or charge. This changes the properties of the space around the singularity, due to effects like frame dragging. It's well established that effects like these can lead to a naked singularity. What's much more uncertain is whether naked singularities can arise from any realistic initial conditions in our universe; this is what the cosmic censorship hypothesis says can't happen. The calculations in the paper describe such a process, which would be a counterexample to cosmic censorship. But they use various approximations, and nobody knows whether those approximations are valid.
No, this is totally incorrect. The Penrose singularity theorem forbids this.
I don't think you're understanding his point correctly. Singularities can be formalized mathematically. That's not the issue. The issue is the inability to use the theory to make predictions, when there are naked singularities. What he's saying is that if we observed a naked singularity, it would not violate the field equations of GR if any unpredictable thing whatsoever came flying out. In fact, actual, literal socks do come flying out of naked singularities. I'm wearing a pair of cotton socks right now, and they came flying out of a naked singularity known as the big bang. The question posed by the cosmic censorship hypothesis is whether other naked singularities could arise in our universe from realistic initial conditions.
The title of the paper is "Destroying black holes with test bodies," and the language about "destroying" black holes is echoed in both the arxiv blog summary and the /. summary. This may be somewhat misleading. They're actually talking about processes that would strip away the event horizon, leaving behind a naked singularity. The black hole wouldn't have been "destroyed," but just changed into a different form. The authors themselves put the word "destroying" in quotes in the paper.
The paper doesn't settle this one way or the other. It says shows that if you use a certain set of approximations, the result is that the event horizon can go away. However, there is no particular reason to believe that the approximation is correct.
The real issue here isn't whether a black hole can actually be transformed this way, it's the question of whether cosmic censorship holds. If cosmic censorship fails, then general relativity is fundamentally flawed as a classical field theory, because it fails to make predictions. John Earman's famous way of expressing this is that anything could come out of a naked singularity: lost socks, green slime, even horrible things like Nixon's "Checkers" speech or Japanese monster-movie creatures.
This "story" is an ad, with promotional language in the slashdot summary like "available for a limited period." The OS isn't open source. Looks like someone knows how to game the firehose.
"Theory" in science doesn't mean the same thing as "theory" in common speech. In everyday speech, "theory" means "what someone thinks." In science, it means something that is capable of making testable predictions, and that has made correct predictions in all the cases where the theory is applicable. For example, Newton's law of gravity is a scientific theory. Although we know it's not true in any absolute sense (because it's only an approximation to general relativity), we know that it is accurate to within certain bounds, under certain conditions.
Creationism and intelligent design are not scientific theories in this sense. They don't testable predictions.
One of the favorite lines of creationists is "it's only a theory." If they mean that evolution is only a (scientific) theory, then they're saying that evolution is totally solid. If they're saying that creationism is only an (alternative) (scientific) theory, then they don't understand what a scientific theory is.
Here it sounds like you just don't have enough scientific knowledge to evaluate the evidence correctly. The current rate of expansion of the universe is not the only evidence for the big bang theory. Within the last 15 years, cosmology has become an exact science. There are extremely tight observational constraints. In addition, one of the things Stephen Hawking built his early career on was proving certain singularity theorems. One of those singularity theorems says that given what we currently observe about the universe, general relativity predicts that there *has* to have been a big bang.
One of the most common things that laypeople misundertand about science is that they think scientists know about things they don't know about, and don't know about things that they do know about. The big bang falls in the latter category. Just because you don't know enough about the evidence to be sure, that doesn't mean there's any doubt remaining among scientists.
The use of the word "controversy" here is taken directly from the creationist playbook. There is "controversy" about whether a big earthquake could cause California to fall off into the Pacific Ocean, but it's only a controversy between two guys sitting in a bar, it's not a controversy among geologists. When creationists say "teach the controversy," they're really asking teachers to present something that's not scientifically controversial as if it were.
This is incorrect. Unix was not designed for security from the ground up. Unix predates the internet by decades. In the 70's and 80's, networking your unix machine meant networking it to other unix machines in the same building. Those other machines were used by people you knew and worked with. If they did something antisocial on the network, you could go knock on their door and politely ask them to stop. For this reason, unix has historically had very poor network security -- by modern standards. For instance, people were still using rlogin well into the 90's -- sending their passwords unencrypted over the network. There was a difference between how unix historically handled network security and how windows handled it, but it was definitely not a matter of ground-up design. Unix adapted more quickly and successfully to the internet. Also, a lot of the security problems on Windows are related to attempts to make it easy to use, whereas unix was never originally aimed at people who had minimal computing skills.
...not very smart. First off, it's silly to equate "smart" to "educated." Smart children of illegal immigrants who pick strawberries don't tend to go to college. Dumb children of business executives tend to go to college and get a degree in something, e.g., education, that doesn't require mastering any speficic, difficult body of knowledge. A college education is a middle-class entitlement in the U.S., like Social Security and Medicare.
The other silly thing about it is that first he tabulates the density of degree holders and finds out that degree holders are more dense where people are more dense. Wow, blinding insight. Then he tries to eliminate the effect of population density using a linear regression, which isn't the right tool for the job. If he wants to eliminate the effect of population density, he should just start with the percentage of the population that has a degree. His linear regression method produces results that obviously don't make much sense, e.g., that Oklahoma City has 544% more people with degrees than you'd expect. (See the note at the bottom of the chart.) Presumably this indicates that not only does every adult in Oklahoma City have a degree, but so do all their children, as do their dogs, cats, and major household appliances.
If what you want is to embed tex in html, you can do it: http://asciimathml.sourceforge.net/ But that doesn't do anything about solving the font problem. You need the fonts, otherwise it can't be rendered. Knuth's Computer Modern fonts were an impressive achievement, but they date back to 1992, and the technology they're built on is obsolete and doesn't fit well with the modern operating systems, or with modern encodings such as unicode. Knuth invented scalable fonts before Adobe reimplemented and commercialized them.
Whatever the merits of this particular disagreement, the term "open source" is definitely getting diluted in the same way that "organic" and "innovative" have been diluted. I went to a symposium in LA last year about the governor's Free Digital Textbook Initiative. There was quite a mix of people there -- teachers, education bureaucrats, open-source software types, authors of free books, people from hardware companies, and people from traditional textbook publishing houses. Everyone was using "open source" like it was magic pixie dust, sprinkling it on everything to make it seem shinier and better. Pearson's rep referred to the consumable workbook it submitted as "free and open-source" -- actually it's just a PDF file that you can download and print, but that you can't redistribute, modify, etc. Houghton Mifflin Harcourt's rep, when questioned about DRM, said that her company was committed to DRM, and envisioned its DRM'd materials being mixed and matched with open-source ones. Both said that they wanted to be service providers (think Red Hat), rather than just content providers (a la Microsoft) -- but, hey, they produce really great content, too. Apple and Dell's reps argued for open formats such as XML.
Part of the reason for the confusion is that people are confused about applying the term to anything other than computer software. When I've mentioned here on slashdot that I was the author of some open-source books, I've sometimes gotten reactions amounting to, "You're an idiot. You don't even know what open source means." This despite the fact that the books are under a GPL-style copyleft license (CC-BY-SA, same as Wikipedia) and their source code (written in a programming language called LaTeX) is openly available and free for redistribution and modification under that license. It sounds like there's similar confusion here because people aren't distinguishing clearly between the issue of WebM as an open format and the implementation of WebM in open-source software. Who the heck cares whether google's reference implementation is open source, as long as the format is openly defined and usable without paying patent royalties? The first implementations of html by NCSA weren't open source according to the modern meaning of the term, but html was certainly an open format.
Actually the GP was correct. Outer space is not a perfect vacuum, so sound waves can travel in it. The reason you can't hear in outer space is basically an impedance mismatch; the mechanism for turning vibration into sound, and then back into vibration, is extremely inefficient. Next thing to understand is that the speed of sound only depends on temperature, not pressure. Therefore the speed of sound in outer space is not drastically different from the speed of sound in the earth's atmosphere. I believe the temperature of the interplanetary medium in the vicinity of the earth's orbit is on the order of a cold night in Antarctica. So if you want to nitpick about the definition of mach factors, you're nitpicking the wrong variable. You should be nitpicking about temperature, not pressure -- and variations in temperature exist even within the earth's atmosphere, but that doesn't stop us from using mach factors to discuss speeds within the atmosphere.