Anyone who has an ebook reader with Wi-Fi is asking for trouble.
It will be a sad day for me when my Sony PRS-300 reader fails to start. This reader has no Wi-Fi.
What is that I hear you say? Turn off the Wi-Fi on the reader? Please, how naive do you think I am?
"The only controls available to those on board were two push-buttons on the center post of the cabin -- one labeled on and one labeled off. The on button simply started a flight from Mars. The off button connected to nothing. It was installed at the insistence of the Martian mental-health experts, who said that human beings were always happier with machinery they thought they could turn off."
Empty space is globally flat, but because gravity is a force with unlimited range no universe with any mass in it is globally flat.
At small enough scale every spacetime is locally flat, although that scale may be very small near a black hole. Only at the location of the singularity is it impossible to find a locally flat reference frame.
During the 1987 Whittier Narrows earthquake every car alarm in the area was set off.
Although I now live in quake-free Texas the first thing I think of when a car alarm goes off is Earthquake! It must be the reptile part of the brain or something. Once my heart starts beating and the rest of my brain starts working I realize there is no earthquake.
Note taking on paper has a number of advantages, but one disadvantage is that the information is indexed only one way: by date. I prefer bound, numbered laboratory notebooks, but unless you have a pretty good idea when you wrote it down it is difficult to find the information you want.
Retrieving information is the reason you write it down, isn't it?
Of course, I learned in a lecture by Jack Kilby that the only reason he was granted the patent on the integrated circuit (and, later, his Nobel Prize) was because he had the bound notebooks he used periodically signed and dated by his manager and then notarized.
I, too, have an e-book reader that does not have the hardware to go on the internet.
Isn't the Unix philosophy to have a single command that does only one job well? "cat", "head", "tail", "ls" are examples of the commands I have in mind. Extend this idea to the real world. I have an e-book reader, a music player, a (dumb) phone, and a wristwatch.
A smart phone is a bit like the Microsoft operating system: it does everything, but does not do any of them well.
Not much of a bargain. Mediocre performance AND the loss of privacy.
I am old enough to remember seeing restrooms marked "white" and "colored". During the bad old days everyone understood that a sign that said "We reserve the right to refuse service to any person" was a code phrase for "whites only". It is sad to read that GitHub is so tone-deaf to the lessons of American history.
"Does a Restaurant Have the Unrestricted Right to Refuse Service to Specific Patrons?
No. The Civil Rights Act of 1964 explicitly prohibits restaurants from refusing service to patrons on the basis of race, color, religion, or natural origin. In addition, most courts don't allow restaurants to refuse service to patrons based on extremely arbitrary conditions. For example, a person likely can't be refused service due to having a lazy eye."
As a happy owner of the Adafruit Blue&White 16x2 LCD+Keypad Kit for Raspberry Pi I have used and modified the software that originally came with this kit.
There are some obvious uses for this kit. Two examples would be displaying its IP address and using the keypad to shutdown the Pi.
However, when I was modifying the software I could not find specific instructions on how to contribute software back to your site. I just checked again this morning (even the FAQ), and, if these instructions exist, I could not find them.
I watched on TV the Mercury capsules launch on TV as a boy, and as a young man I worked on the Galileo mission. Of all the books I have read about the space program none is better than Chris Karft's "Flight - My Life in Mission Control".
It is not an engineering book, but a book written by an engineer. For example, the description of the problems during Apollo 13 are described better here than anywhere. He never tries to make hemself or anyone else look better than they actually were. He often is quite critical of NASA's spin control.
The velocity of the craft does matter, and I will explain why.
If the velocity of the craft is much greater than the particles (think of dust floating in the air), then the craft will indeed sweep out all the particles in its line of motion.
However, the the velocity of the craft is much less that the particles (think cosmic rays in interplanetary space), then there will be the same number of collisions per unit time during the trip. A five hundred day trip will have ten times the number of collisions as a fifty day trip. Consequently, the faster your craft travels, the fewer particles you encounter during your journey.
I had the pleasure of listening to you speak at Caltech in the 1980s about the Nuclear Freeze Movement. You were a supporter even though you indicated that since the number of nuclear weapons was decreasing (at that time), keeping the current number of nuclear weapons was not desirable.
Thirty years have passed. Do you think this movement accomplished any of their goals?
Speaking as someone who was classified 1-A in 1973 I would claim you left off one of his important actions:
"On January 27, 1973, Secretary of Defense Melvin R. Laird announced the creation of an all-volunteer armed forces, negating the need for the military draft."
There were 279 students enrolled in this class. Assuming a ten minute oral exam for each and two minutes to grade the answers it takes 55.8 hours to examine all the students. This oral exam would take at least two weeks in a 14 week semester, and ten minutes is really too little time to judge the work of an entire semester.
If anyone other than the professor grades the student, then they cry foul.
If the exams begin in the fifth week of the 14 week semester, the students examined last cry foul since they must study significantly more material.
There should be only twenty students in a class? Good luck with that. I suppose you could raise tuition and hire more professors or have the classes taught by lecturers.
Actually, in the USA most classes are taught by lecturers, and the classes are still huge.
"Failure is not an Option" is a good book, but Christopher C. Kraft's book "Flight" covers many of the same events better. I closely followed the Mercury, Gemini, and Apollo missions at the time they occurred and find Kraft's discussion of the engineering problems and solutions clearer, and he is not afraid to be critical of men (like John Glenn) when he believes they were wrong.
Kraft also originated the concept of the Mission Control Center.
I enjoyed "The Sand Reckoner", Gillian Bradshaw's fictional account of Archimedes. (I also enjoyed the original "Sand Reckoner" by Archimedes, but that was not fiction.)
Gillian Bradshaw is a well regarded historical novelist, and there is mathematical content in the novel if you know what to look for. In the book Archimedes' father dies, and Archimedes distracts by working on his mathematics. The reader does not know what he is working on until he tells his sister "It's more than ten seventy-firsts and less than a seventh." Pi minus three, of course.
However, if you are familiar with his proof, the suggestion that he could work this out in a single evening suggests that this is a fantasy rather than a historical novel.
Back in the 1990s I worked as a software developer at a company that monitored a large amount of data in real time. Not stock market data or particle accelerator data, but telephone switching data (SS7). They began selling the hardware/software package in the late 1980s.
If this amount of data can be monitored and displayed in real time using 1980s technology, why can't the SEC do it now for stock market data?
In equity trading there appears to be at least three time scales. Fundamental analysis functions over a period of months. Technical analysis (used by day traders) works over periods of minutes and seconds. And then there is high frequency trading (accounting for over 70% of equity trades in the US in 2010) which works on the millisecond or microsecond scale.
Some persons in this forum has suggested that the millisecond scale be eliminated.
Front running has been illegal for a long time in the USA, but as long as the second trade is made after the initial trade (even a microsecond later) it is legal. My problem with HFT is that if a person does not have access to a millisecond trading, then for all practical purposes the second trade is front running.
In December 2010 Frank Zhang of the Yale School of Management published a paper claiming that HFT accounted for 70% of the dollar trading volume in the U.S. capital market.
David Woodcock, the Regional Director of the SEC, confirmed this number in a lecture I attended at the University of Texas at Dallas in May.
As far as HFT reform goes, I think that ship has sailed. Or, quoting from the film "Giant": "You should have shot that fella a long time ago. Now he's too rich to kill."
Since when has the search for extraterrestrial life been part of NASA's mandate? And why must the search for life be the sole reason for NASA to launch a scientific mission?
Here are NASA's objectives according to the National Aeronautics and Space Act:
"(1) The expansion of human knowledge of the Earth and of phenomena in the atmosphere and space.
(2) The improvement of the usefulness, performance, speed, safety, and efficiency of aeronautical and space vehicles.
(3) The development and operation of vehicles capable of carrying instruments, equipment, supplies, and living organisms through space.
(4) The establishment of long-range studies of the potential benefits to be gained from, the opportunities for, and the problems involved in the utilization of aeronautical and space activities for peaceful and scientific purposes.
(5) The preservation of the role of the United States as a leader in aeronautical and space science and technology and in the application thereof to the conduct of peaceful activities within and outside the atmosphere.
(6) The making available to agencies directly concerned with national defense of discoveries that have military value or significance, and the furnishing by such agencies, to the civilian agency established to direct and control nonmilitary aeronautical and space activities, of information as to discoveries which have value or significance to that agency.
(7) Cooperation by the United States with other nations and groups of nations in work done pursuant to this chapter and in the peaceful application of the results thereof.
(8) The most effective utilization of the scientific and engineering resources of the United States, with close cooperation among all interested agencies of the United States in order to avoid unnecessary duplication of effort, facilities, and equipment.
(9) The preservation of the United States preeminent position in aeronautics and space through research and technology development related to associated manufacturing processes."
If you know that this question is meaningless and why, then you are ready to study general relativity.
Otherwise take a course in Special Relativity or read and study "Spacetime Physics" by E F Taylor and J A Wheeler. Wheeler once told me that he believed that every figure should have as much information as 10 pages of text, and some figures in "Spacetime Physics" come near his goal.
IMHO most scientists who can perform the algebra and solve problems in Special Relativity do not really understand the implications of their answers.
From what I have heard, the reason it took 52 years to get this spacecraft into space was political, not technical.
There is no doubt that the technology developed to measure these parameters is very impressive. The real question is whether or not it was worth the effort.
When I was at JPL in the 1980s a person who had published numerous papers in both experimental and theoretical relativity explained why scientists within the space program were not supporting this project. Since this conversation took place thirty years ago I must paraphrase:
"No modern theory of gravity predicts anything else, and if the measurements showed anything but the predicted results it would be assumed to be an experimental error. Unlike the technology used to search for gravitational radiation (which is also used to study the atmospheres of planets), the hardware in this spacecraft cannot be used for any other scientific experiment."
So for 52 years the money has been used for other science. For a much more worthy project read about the recently canceled LISA project.
If you wish to read about the politics of how a science project is chosen by NASA I can think of no better description that Steven W. Squyres' "Roving Mars" where he describes how the Mars Rovers were nearly canceled.
Slashdot Mirror
Why doesn't hardware designed for schoolchildren not have a shutdown button?
Would a button or even a pair of jumpers really add that much to the cost of materials?
Anyone who has an ebook reader with Wi-Fi is asking for trouble.
It will be a sad day for me when my Sony PRS-300 reader fails to start. This reader has no Wi-Fi.
What is that I hear you say? Turn off the Wi-Fi on the reader? Please, how naive do you think I am?
"The only controls available to those on board were two push-buttons on the center post of the cabin -- one labeled on and one labeled off. The on button simply started a flight from Mars. The off button connected to nothing. It was installed at the insistence of the Martian mental-health experts, who said that human beings were always happier with machinery they thought they could turn off."
- Kurt Vonnegut, The Sirens of Titan
The idea of using Lunar Seismic activilty to measure gravitational radiation dates back to the 1970s.
http://en.wikipedia.org/wiki/A...
In particular, consider the purpose of the Lunar Surface Gravimeter (LSG).
I do not believe that what you wrote is correct.
Empty space is globally flat, but because gravity is a force with unlimited range no universe with any mass in it is globally flat.
At small enough scale every spacetime is locally flat, although that scale may be very small near a black hole. Only at the location of the singularity is it impossible to find a locally flat reference frame.
During the 1987 Whittier Narrows earthquake every car alarm in the area was set off.
Although I now live in quake-free Texas the first thing I think of when a car alarm goes off is Earthquake! It must be the reptile part of the brain or something. Once my heart starts beating and the rest of my brain starts working I realize there is no earthquake.
Note taking on paper has a number of advantages, but one disadvantage is that the information is indexed only one way: by date. I prefer bound, numbered laboratory notebooks, but unless you have a pretty good idea when you wrote it down it is difficult to find the information you want.
Retrieving information is the reason you write it down, isn't it?
Of course, I learned in a lecture by Jack Kilby that the only reason he was granted the patent on the integrated circuit (and, later, his Nobel Prize) was because he had the bound notebooks he used periodically signed and dated by his manager and then notarized.
I, too, have an e-book reader that does not have the hardware to go on the internet.
Isn't the Unix philosophy to have a single command that does only one job well? "cat", "head", "tail", "ls" are examples of the commands I have in mind. Extend this idea to the real world. I have an e-book reader, a music player, a (dumb) phone, and a wristwatch.
A smart phone is a bit like the Microsoft operating system: it does everything, but does not do any of them well.
Not much of a bargain. Mediocre performance AND the loss of privacy.
I am old enough to remember seeing restrooms marked "white" and "colored". During the bad old days everyone understood that a sign that said "We reserve the right to refuse service to any person" was a code phrase for "whites only". It is sad to read that GitHub is so tone-deaf to the lessons of American history.
from http://www.legalmatch.com/law-library/article/restaurants-right-to-refuse-service.html
"Does a Restaurant Have the Unrestricted Right to Refuse Service to Specific Patrons?
No. The Civil Rights Act of 1964 explicitly prohibits restaurants from refusing service to patrons on the basis of race, color, religion, or natural origin. In addition, most courts don't allow restaurants to refuse service to patrons based on extremely arbitrary conditions. For example, a person likely can't be refused service due to having a lazy eye."
As a happy owner of the Adafruit Blue&White 16x2 LCD+Keypad Kit for Raspberry Pi I have used and modified the software that originally came with this kit.
There are some obvious uses for this kit. Two examples would be displaying its IP address and using the keypad to shutdown the Pi.
However, when I was modifying the software I could not find specific instructions on how to contribute software back to your site. I just checked again this morning (even the FAQ), and, if these instructions exist, I could not find them.
How does one contribute back?
I watched on TV the Mercury capsules launch on TV as a boy, and as a young man I worked on the Galileo mission. Of all the books I have read about the space program none is better than Chris Karft's "Flight - My Life in Mission Control".
It is not an engineering book, but a book written by an engineer. For example, the description of the problems during Apollo 13 are described better here than anywhere. He never tries to make hemself or anyone else look better than they actually were. He often is quite critical of NASA's spin control.
The velocity of the craft does matter, and I will explain why.
If the velocity of the craft is much greater than the particles (think of dust floating in the air), then the craft will indeed sweep out all the particles in its line of motion.
However, the the velocity of the craft is much less that the particles (think cosmic rays in interplanetary space), then there will be the same number of collisions per unit time during the trip. A five hundred day trip will have ten times the number of collisions as a fifty day trip. Consequently, the faster your craft travels, the fewer particles you encounter during your journey.
Professor Dyson
I had the pleasure of listening to you speak at Caltech in the 1980s about the Nuclear Freeze Movement. You were a supporter even though you indicated that since the number of nuclear weapons was decreasing (at that time), keeping the current number of nuclear weapons was not desirable.
Thirty years have passed. Do you think this movement accomplished any of their goals?
Thank you.
Speaking as someone who was classified 1-A in 1973 I would claim you left off one of his important actions:
"On January 27, 1973, Secretary of Defense Melvin R. Laird announced the creation of an all-volunteer armed forces, negating the need for the military draft."
It is a violation of federal law in the USA to fire a worker for discussing their salary with a co-worker. This law dates back to the New Deal.
http://www.staffingtalk.com/allowed-discuss-salary-co-workers/
You wonder why oral exams are not more common?
There were 279 students enrolled in this class. Assuming a ten minute oral exam for each and two minutes to grade the answers it takes 55.8 hours to examine all the students. This oral exam would take at least two weeks in a 14 week semester, and ten minutes is really too little time to judge the work of an entire semester.
If anyone other than the professor grades the student, then they cry foul.
If the exams begin in the fifth week of the 14 week semester, the students examined last cry foul since they must study significantly more material.
There should be only twenty students in a class? Good luck with that. I suppose you could raise tuition and hire more professors or have the classes taught by lecturers.
Actually, in the USA most classes are taught by lecturers, and the classes are still huge.
"Failure is not an Option" is a good book, but Christopher C. Kraft's book "Flight" covers many of the same events better. I closely followed the Mercury, Gemini, and Apollo missions at the time they occurred and find Kraft's discussion of the engineering problems and solutions clearer, and he is not afraid to be critical of men (like John Glenn) when he believes they were wrong.
Kraft also originated the concept of the Mission Control Center.
I enjoyed "The Sand Reckoner", Gillian Bradshaw's fictional account of Archimedes. (I also enjoyed the original "Sand Reckoner" by Archimedes, but that was not fiction.)
Gillian Bradshaw is a well regarded historical novelist, and there is mathematical content in the novel if you know what to look for. In the book Archimedes' father dies, and Archimedes distracts by working on his mathematics. The reader does not know what he is working on until he tells his sister "It's more than ten seventy-firsts and less than a seventh." Pi minus three, of course.
However, if you are familiar with his proof, the suggestion that he could work this out in a single evening suggests that this is a fantasy rather than a historical novel.
A good read, in either case.
The method described here seems like a straightforward idea.
Wasn't a similar idea posted to slashdot five years ago?
http://slashdot.org/comments.pl?sid=440258&cid=22283136
The fish will now have the opportunity to turn the caffeine into theorems.
(With apologies to Alfred Renyi.)
http://en.wikipedia.org/wiki/Alfr%C3%A9d_R%C3%A9nyi
Back in the 1990s I worked as a software developer at a company that monitored a large amount of data in real time. Not stock market data or particle accelerator data, but telephone switching data (SS7). They began selling the hardware/software package in the late 1980s.
If this amount of data can be monitored and displayed in real time using 1980s technology, why can't the SEC do it now for stock market data?
In many physical problems (like the study of water waves) there are multiple length and time scales, each of which can be approximated separately. See
http://en.wikipedia.org/wiki/Method_of_multiple_scales
In equity trading there appears to be at least three time scales. Fundamental analysis functions over a period of months. Technical analysis (used by day traders) works over periods of minutes and seconds. And then there is high frequency trading (accounting for over 70% of equity trades in the US in 2010) which works on the millisecond or microsecond scale.
Some persons in this forum has suggested that the millisecond scale be eliminated.
http://en.wikipedia.org/wiki/Front_running
Front running has been illegal for a long time in the USA, but as long as the second trade is made after the initial trade (even a microsecond later) it is legal. My problem with HFT is that if a person does not have access to a millisecond trading, then for all practical purposes the second trade is front running.
In December 2010 Frank Zhang of the Yale School of Management published a paper claiming that HFT accounted for 70% of the dollar trading volume in the U.S. capital market.
David Woodcock, the Regional Director of the SEC, confirmed this number in a lecture I attended at the University of Texas at Dallas in May.
As far as HFT reform goes, I think that ship has sailed. Or, quoting from the film "Giant": "You should have shot that fella a long time ago. Now he's too rich to kill."
Since when has the search for extraterrestrial life been part of NASA's mandate? And why must the search for life be the sole reason for NASA to launch a scientific mission?
Consider http://www.nasa.gov/offices/ogc/about/space_act1.html
Here are NASA's objectives according to the National Aeronautics and Space Act:
"(1) The expansion of human knowledge of the Earth and of phenomena in the atmosphere and space.
(2) The improvement of the usefulness, performance, speed, safety, and efficiency of aeronautical and space vehicles.
(3) The development and operation of vehicles capable of carrying instruments, equipment, supplies, and living organisms through space.
(4) The establishment of long-range studies of the potential benefits to be gained from, the opportunities for, and the problems involved in the utilization of aeronautical and space activities for peaceful and scientific purposes.
(5) The preservation of the role of the United States as a leader in aeronautical and space science and technology and in the application thereof to the conduct of peaceful activities within and outside the atmosphere.
(6) The making available to agencies directly concerned with national defense of discoveries that have military value or significance, and the furnishing by such agencies, to the civilian agency established to direct and control nonmilitary aeronautical and space activities, of information as to discoveries which have value or significance to that agency.
(7) Cooperation by the United States with other nations and groups of nations in work done pursuant to this chapter and in the peaceful application of the results thereof.
(8) The most effective utilization of the scientific and engineering resources of the United States, with close cooperation among all interested agencies of the United States in order to avoid unnecessary duplication of effort, facilities, and equipment.
(9) The preservation of the United States preeminent position in aeronautics and space through research and technology development related to associated manufacturing processes."
"What is happening on Mars right now?"
If you know that this question is meaningless and why, then you are ready to study general relativity.
Otherwise take a course in Special Relativity or read and study "Spacetime Physics" by E F Taylor and J A Wheeler. Wheeler once told me that he believed that every figure should have as much information as 10 pages of text, and some figures in "Spacetime Physics" come near his goal.
IMHO most scientists who can perform the algebra and solve problems in Special Relativity do not really understand the implications of their answers.
From what I have heard, the reason it took 52 years to get this spacecraft into space was political, not technical.
There is no doubt that the technology developed to measure these parameters is very impressive. The real question is whether or not it was worth the effort.
When I was at JPL in the 1980s a person who had published numerous papers in both experimental and theoretical relativity explained why scientists within the space program were not supporting this project. Since this conversation took place thirty years ago I must paraphrase:
"No modern theory of gravity predicts anything else, and if the measurements showed anything but the predicted results it would be assumed to be an experimental error. Unlike the technology used to search for gravitational radiation (which is also used to study the atmospheres of planets), the hardware in this spacecraft cannot be used for any other scientific experiment."
So for 52 years the money has been used for other science. For a much more worthy project read about the recently canceled LISA project.
If you wish to read about the politics of how a science project is chosen by NASA I can think of no better description that Steven W. Squyres' "Roving Mars" where he describes how the Mars Rovers were nearly canceled.