I personally disagree about Griffiths, but hey, that's what great about Physics- everyone is entitled to their own opinion about which books are best, because everyone learns different. I have a hard time with math, and my theory isn't that great (if I haven't mentioned above, I'm an experimentalist), so Griffiths was really good for someone like me. One size does not fit all!
I'm not familiar with those QM texts. I also have used Baym (and was taught by the man himself) and Merzbacher, but Shankar was by far my favorite. His first chapter finally made the language of QM (linear algebra) click for me. Again, I think my opinions are heavily influenced by my mathematical abilities and my lack of knack for theory.
I've heard so many good things about Goldstein that I may just go ahead and pick up a copy for myself. My intro to the Hamiltonian was rough and incomplete (I never attended a CM lecture in undergrad due to a schedule conflict), and I've always wanted a better handle on it for the purposes of QM. I totally agree with your stressing of the importance of CM in that it makes understanding QM easier, and a little more physical.
I've heard good things about Boas. For some strange reason, I don't have a copy of this, and Arfken has sufficed for my needs, which are not very high when it comes to math methods. An aspiring astrophysicist may need more math than a condensed matter experimentalist (all that GR), so it may behoove such a person to pick up Boas. Good recommendations.
Seriously, yes. Comparing physics to computer science is like comparing apples to UNIX. There is a little cross-over, but not much, and certainly not in the manner in which each subject is taught. It also might speak a bit about the lack of quality CS texts (not that there are many quality physics texts overall). The level of rigor in graduate texts is much higher than in undergrad texts, and from my own personal experience, there is simply no way I could have handled most of my grad texts when I was an undergrad- I didn't know enough, and my math skills sucked (and are only slightly improved now). It does get a bit expensive, but some foolish physics students actually sell their books back, enabling people like me to buy perfectly good used texts on the cheap, or sometimes, they even GIVE them away. Physics texts are invaluable as references, even after taking a class, which is why most physicists have stacks of them- we can't remember how to do everything we've ever learned, but a little reminder goes a long way.
The vast majority of the recommendations here are top notch. A lot of which book to use really is personal preference and background. Here are my personal choices after having been in 3 separate Physics departments. Also, you should consider looking at ANY of the Landau-Lifshitz texts. These Soviet scientists wrote comprehensive texts that might be right up your alley as someone with a math background. I only wish I could understand them more, their physics is really beautiful.
First off, a general reference book. I recommend the Halliday and Resnick series. Buy this used. It is basically an encyclopedia of physics that is presented at the intro undergraduate level. I use it frequently when working through problems outside my specific area of expertise.
Electricity and Magnetism: Three books. Griffiths, Purcell, and Jackson. The first is a classic undergrad text, the second is a more advanced undergrad text, and the last is the standard graduate text in E&M.
Quantum Mechanics: Griffiths' undergrad text is a must, though it is not very mathematically rigorous. I recommend Shankar as a supplement- Shankar is used as both a grad and undergrad text. I'm an experimentalist who stopped learning formal quantum mechanics after 1 year of graduate study, so Shankar may not be enough for you depending on your interests. Check out other's recommendations. Griffiths and Shankar are very good intro and reference books.
Statistical Mechanics- I used Kittel and Kroemer as an undergrad, and it's OK, a little dated. Huang was my grad text, and it is also OK. I don't have strong feelings here. Landau and Lifshitz may be better for you
Classical Mechanics- Marion and Thorton was my undergrad text. Personally, I don't think the CM text really matters. They are all equally bad. The basics they teach you are what a Langrangian is, and unfortunately always underemphasized what a Hamiltonian is (used REPEATEDLY in QM).
Finally, make sure to get a good Mathematical Methods book, even if you really understand math well (I am sure you do). I recommend Arfken as a reference tome, and the Schaum's outline as a handy desktop reference for solving various partial differential equations. Past that, you should be able to pick up texts cheap used from fellow students, or on eBay. Good luck!
Lol. I have to say, chances are that it was not a particularly difficult topic that was being presented, as much as a particularly poor presentation. Physicists are usually not very good at explaining what they do to students (sad).
This is only true if you are using off-the-shelf parts from companies like Bruker and Varian. My spectrometer is made by Tecmag, and the rest of my setup is home-built. I don't care if the center frequency shifts or not- it'll do that with or without He fills. And the lineshape changes too- that's what shims are for. Also, I don't bother with tuning because for me, the logistics of tuning after each cryogen fill or sample change are impossible, and I'd never acquire any data. In general, I am not very interested in doing super high-res NMR- my setup is originally designed to do microMRI where shifts on the order of a few ppb just don't matter. All those changes get washed out when your start turning on gradients and frequency/phase encoding. That being said, my shifts are no where near as big as yours. At least 200 times smaller.
The inductive losses should be zero if it is a DC current. I believe this to be true because I have a 7 Tesla SC magnet that has the same electrons running around inside of it that it did over 8 years ago. The only thing I have done to maintain this current is add liquid helium twice a year (it boils off) and liquid nitrogen every week. The liquid helium costs about 400-500 bucks a year, and the LN2 is virtually free- I use maybe 40 or 50 L a week, so over a year, that is MAYBE a thousand bucks, if even that. It is so inexpensive (cheaper than pop) that we don't pay for it out of our research group's funds, our department or perhaps the University just subsidizes it.
Yes, the pre-Nebula Award SFHoF vol.1 is perhaps the greatest selection of sci-fi short stories ever put together. No author has more than one entry in the book, so you get exposed to a wide swath of different writers. Look for it on eBay!
The ultimate future of solid state lighting resides in a combination of two existing/developing technologies. The first is the LED, already in commercial production, which will continue to be refined with respect to spectral output. The second is a technology that is mostly still in the lab- visible spectrum photonic bandgap materials. Basically, these are kind of "perfect reflectors". By creating an LED in a photonic bandgap material, reabsorption of emitted photons would be eliminated, or at the very least steeply curbed. This would increase the effective efficiency of the LED, giving you more light for the same amount of electrical energy. It would make lighting incredibly inexpensive with regards to energy usage, but the when the combination of LEDs and PBG materials comes out, it will be very expensive, just as with any new technology. It will eventually prove superior to other lighting paradigms due to longevity (how often do LEDs burn out?) and operational costs, especially for industrial users whose premises use a lot of light 24 hours a day.
I don't understand this Slashdot and in general, IT personnel, infatuation with Ron Paul. He is really just the Republican version of Dennis Kucinich in the sense that both are kooky extremists who bring up good points, but in the end are too far too the left and right to be suitable to lead this country. And as for Ron Paul sticking to his guns... why is so much value attached to that? It can be looked at as a foible as well as a virtue. All in all, I think that Ron Paul more poorly represents geeks than many of them realize.
I digress. My plans as president. Hmmm. So many things... well first off, I believe in nationalizing education. We are falling behind other countries very quickly, and without a strong lead in technology, our economy is doomed to fail. I've seen numerous state boards of education fuck up their states' curricula, especially with regards to science, so I think state control, and even more importantly, local community control causes way more harm than good. Plus, as an Ohioan, I can see that funding schools via property taxes is an abject failure, and encourages poor, ignorant people to stay poor and ignorant. Nationalizing education gets us off the property tax crack, or whatever other funding schemes various states/municipalities have in place. We need to all be on the same page, learning the same material. Is science really different in Texas and Kansas than it is in New York or Oregon? Last time I checked, no, but it is taught differently (see evolution), which is crap. We also need to have national standards for teachers. Basically, there is an overabundance of shitfucks in our public schools, who partied hardy and got shitty grades in college, so they became teachers. That's not always true, and there are many good, if not great teachers out there, but they tend to congregate in the better school systems (see funding issues above) because they don't want to deal with the problems associated with poor, ignorant people's kids, as well as the shittier pay. We need to set higher standards and requirements for K-12 teachers, and provide economic incentives to encourage qualified people to enter the teaching profession and meet those goals.
Secondly, I would nationalize health care. It makes little sense to have a private industry provide something that EVERYBODY needs. It takes away the maximum advantages of economy of scale. I am not saying that there is not room for private health care, there still would be. But doctors should be forced to work at set prices, determined by local cost of living, that is paid out by the federal government. If they don't like those set prices, they are free to go out on their own and charge what they will to whomever is willing to pay for it. But otherwise, they get paid by the feds. And there definitely needs to be more accountability on the part of doctors- they should not be financially rewarded for screwing up by getting paid for a second operation or procedure. Financial incentives should be provided for more GPs, and for more doctors period in rural areas, or those working in high-traffic urban hospitals. Will this lower pay for doctors? Probably, but that is not necessarily a bad thing, unless you're a doctor. And to be honest, doctors are overrated, and have an overly large sense of importance. They are basically mechanics for the human body, with good memories, and good hands if they are a surgeon. In my opinion, that should not be worth more than being an innovative scientist or engineer. And don't give me this bullshit about the time doctors spend in med school and residency, etc. Try getting a PhD in science, followed by a post doc, maybe a government lab position, then trying to climb up the tenure track ladder, all to be rewarded by a salary that may not even clear six figures when you are in your early 50's. There is no reason for medical doctors and science/engineering doctorates to have such a large difference in their pay. It is economically wasteful to be paying bio-mechanics that much.
Where the energy gets deposited depends on the composition. For instance, an icy asteroid is more likely to deposit energy in the atmosphere as the ice it is partially made up of melts, vaporizes, or perhaps even sublimes. The latent heat of vaporization of water is much much less than that of rock, so a mostly rock asteroid is more likely to stay intact by the time it reaches the surface, hence depositing more of its initial energy into the surface and lower atmostphere.
It seems that while the asteroid itself did not cause as much damage as previously believed (3-5 megatons vs 10-20), the asteroid was most likely much smaller than had been estimated. Too bad the article doesn't give some numbers about the size. Pretty scary thinking about one of these things hitting on top of or near a major population center.
I would say this- the transistor led to virtually all modern electronics. In fact, it is the basis of our modern life and economy. Without it, we could not possibly be where we are today. While tubes may indeed have been the size of the original transistor in 1947/1948, there is no way it could have miniaturized at the rate transistors have- in fact, there is most likely a hard limit to the smallest tube size. Finally, the transistors importance over tubes was that it acted as a miniaturized amplifier. Its true value lay in its ability to facilitate digital (Boolean) logic, which led us to develop computers. The transistor is the single-most important invention of the human race in the last 100 years, and perhaps even the last 200 (though good arguments could be made for penicillin/antibiotics).
Well, so one would think. Unfortunately, there is a fairly hard limit to lowering diffusion via temperature, which is that water freezes at 0C. Once you have a solid, NMR/MRI becomes much more difficult- relaxation times decrease by orders of magnitude (no more motional narrowing), causing short-lived signal and broad linewidths. And even lowering the temperature to just above freezing will only nominally change the diffusion coefficient, probably not more than a factor of 5 or so.
There are hard limits to resolution. You mentioned one in the SNR issue. But you signal average till kingdom come to get around that. Another issue is that at very small voxel sizes, diffusion becomes important, and you get blurring in your image as a result. Understanding how important this is depends on the tissue type, of which I am not an expert (I am not a clinical MRI guy, but a research and development type).
BTW, the SNR enhancement from stronger fields goes roughly as the square of the field, so doing these same scans in a 7 Tesla scanner, all other things being equal (which they wouldn't be), would increase the SNR by over 50,000. That is using a 30 mT field, skipping over the 46 microTesla detection field. Honestly, they might be better off trying to do PEDRI, and excite electron resonances, and then couple to the protons via the Overhauser effect to improve their SNR at the higher field. Basically reverse what they are doing now- excite at 46 microT, and detect at 30mT. Or even polarize at 30mT, excite electrons at 46microT, and detect at 30mT. The higher field affects both the net polarization of the spins AND the sensitivity of the detection coils, which is why you'd want to come back to 46 mT. Of course, I am not thinking of using SQUIDS, but more conventional style coils...
From having read the article and comments here, I'd like to make some observations. First off, it seems like there is a very sizable percentage of Slashdot posters who are in the IT community. My anecdotal evidence about IT people is that some of them have this anti-education bias, in that they themselves did not seek out higher education or post-graduate degrees, and have done just fine, which means that they didn't need that higher education. Therefore, higher education is bunk, because you don't need it be successful. I definitely do not agree with that, because basically in the hard sciences, you go nowhere without your PhD.
The other observation I have made is that there is a tendency to look at IT people as being part of this "tech class" that includes scientists and engineers. To me, you need to make a clear distinction, because doing IT is very different than working as an engineer or as a research scientist. You simply don't need the same type of education because you don't do a similar type of job. Yet business pundits often times approach the problem and invoke IT job numbers, which are pretty much irrelevant to science and engineering.
I am in Physics. Half of the graduate students in my department are foreign, mostly from East Asia. I can tell you right now that that has more to do with the lack of domestic talent than the quality of that talent- in other words, there are still not enough domestic physics majors. And it is not that we are trying to attract foreign talent because they are willing to work for less. A friend of mine who is an international student just got a job offer from a well-known tech company that is close to 6 figures. That doesn't sound like peanuts to me. The problem is that as high as that sounds, it may not be high enough. Science and engineering pay better than many jobs, but they do not pay enough to encourage more domestic students to study those fields in college and then go on to get jobs. And while the American public may think it is hunky-dory to pay a PhD physicist 75K a year to do his job, I can assure you that it is not OK. For some reason, Americans are willing to pay doctors hundreds of thousands of dollars a year, but a comparably-educated scientist gets to be merely middle-class, despite working longer hours.
To sum it up, scientists are underpaid, underappreciated, and well-below the national numbers necessary to ensure our continued technological dominance over other countries. Business people are cheap, and usually know next to nothing when it comes to science, and their advice should not be taken seriously, even with a boulder of salt. Business is what engineers who can't cut it in undergrad go into, so there are people there who are jaded against S&E to begin with (not that there are huge numbers, but I think most people who went to college know someone who fits this description). They are looking to cut costs, and one way to do that is disparage scientists and engineers, who as professionals, are not cheap to employ. Unfortunately, what they are being paid right now is STILL not enough, so businesses that employ them are in fact getting a great deal. If American business become convinced that we do not need more scientists and engineers, we are all screwed. An undereducated populace is guaranteed to lose money as jobs that don't involve their heads go the way of the horse and buggy, or even more likely, go overseas.
Avoid the Big Bang Theory like the plague it is
on
The Fall Geek TV Lineup
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· Score: 3, Interesting
Please do not watch this show. It is utter crap. I'm a grad student in physics, and am offended by the stereotypes it portrays. Sure, I'm a geek, as evidenced by me posting here. But I also like to have fun, know how to socialize, have had many many relationships with the opposite sex that for the most part have been positive, and basically am known for my personality rather than my career choice, JUST LIKE MOST NORMAL PEOPLE. Oh, and I really hate most Star Trek related things. I did enjoy (but am not a psychotic fan of) the original series (more for its campiness and originality), as well as the 2nd-4th movies. And I like Star Wars, just like any other red-blooded American male who was a little kid in the early 1980's. But that's it. Also, I love sports. Especially baseball, which for some reason seems to be common among physicists (maybe it's all those statistics). Put me in a bar on a fall Saturday or Sunday with football on the TV and I'm happy. Why can't physicists be portrayed for what we really are, which is normal people who happen to do physics? Look at Einstein! Witty, charismatic, and womanizer! Now that's a physicist!
Well, shitty for Wheel of Time fans, Robert Jordan is dead. Looks like you'll never know what happens to the characters. Oh wait, you wouldn't have anyways. Rumor has it that the twelfth and final book had most of the main characters discussing what to have for dinner for more than 35 chapters.
I am convinced that the way to get people in to science is to get down to brass-tax much earlier on;
get down to the real physics of what's going on. In my opinion, there is no reason that the bright kids could not be walked through
a solution to the Schrodinger Equation's solution for the Hydrogen atom energy levels at sixteen. There is no reason you can't teach them
basic calculus either. There's no reason why you can't walk them through how to derive the equations for circular motion.
I disagree with you on this particular point. Yes it is true that you don't want to water things down. But if you are serious about advocating these particular examples, I believe that you are wrong. I know this because, A. I have solved the hydrogen atom starting from the Schrodinger equation, and B. because I have taught high school science in the US, specifically physics, to 15 and 16 year old children of all kinds of ability levels.
The fact of the matter is that while that may have been OK for you to have studied at the age, it most certainly is NOT for the overwhelming majority of students, by which I mean 99.9%. That is a literal number, not figurative. I myself would have been unable to understand the quantum mechanical derivation of the Bohr model of the atom at the age of 16, even if someone had carefully explained it to me. There is just no way to do that and impart deep understanding of both the process and the end result. You are better off just presenting the solution, because that at least is something that students can understand. 16 year olds (again, 99.9% of them) are not going to understand calculus (did I mention it is multivariable vector calculus in 3 dimensions?), let alone partial differential equations (e.g. Schrodinger) and spherical harmonics, all of which are needed to understand the "walkthrough".
Basically what I am saying is that it is unrealistic to expect even a minority of students to understand such high level concepts that they are not taught in the United States until the sophomore and junior years of university, and even then only to a select number of students (in physics, electrical engineering, and maybe a few others). That is a good way to turn students off to science- making the barrier unnecessarily high. Sometimes, it is OK to gloss over the math, because there is nothing to be gained there. Most students, even the bright ones, are not going to be come physicists, so why subject them to something that is so specific?
Doing a derivation on something like circular motion is much more appropriate. Why? Because it is something that students can relate to (they have all experienced circular motion, centripetal force etc.), unlike quantum mechanics which is inherently non-intuitive, and the math is orders of magnitude simpler (algebra vs spherical harmonics). On that point I am in agreement. But you must be careful about how you phrase your argument and present your viewpoint because the minute you start spouting off about showing students how to derive the Bohr model of the atom from the Schrodinger equation, you are going to turn people because they don't even know what the Schrodinger equation is. We don't want to dumb down science, but at the same time it needs to be accessible to students beyond the future Stephen Hawkings of the world.
Slashdot Mirror
I personally disagree about Griffiths, but hey, that's what great about Physics- everyone is entitled to their own opinion about which books are best, because everyone learns different. I have a hard time with math, and my theory isn't that great (if I haven't mentioned above, I'm an experimentalist), so Griffiths was really good for someone like me. One size does not fit all!
I'm not familiar with those QM texts. I also have used Baym (and was taught by the man himself) and Merzbacher, but Shankar was by far my favorite. His first chapter finally made the language of QM (linear algebra) click for me. Again, I think my opinions are heavily influenced by my mathematical abilities and my lack of knack for theory.
I've heard so many good things about Goldstein that I may just go ahead and pick up a copy for myself. My intro to the Hamiltonian was rough and incomplete (I never attended a CM lecture in undergrad due to a schedule conflict), and I've always wanted a better handle on it for the purposes of QM. I totally agree with your stressing of the importance of CM in that it makes understanding QM easier, and a little more physical.
I've heard good things about Boas. For some strange reason, I don't have a copy of this, and Arfken has sufficed for my needs, which are not very high when it comes to math methods. An aspiring astrophysicist may need more math than a condensed matter experimentalist (all that GR), so it may behoove such a person to pick up Boas. Good recommendations.
Seriously, yes. Comparing physics to computer science is like comparing apples to UNIX. There is a little cross-over, but not much, and certainly not in the manner in which each subject is taught. It also might speak a bit about the lack of quality CS texts (not that there are many quality physics texts overall). The level of rigor in graduate texts is much higher than in undergrad texts, and from my own personal experience, there is simply no way I could have handled most of my grad texts when I was an undergrad- I didn't know enough, and my math skills sucked (and are only slightly improved now). It does get a bit expensive, but some foolish physics students actually sell their books back, enabling people like me to buy perfectly good used texts on the cheap, or sometimes, they even GIVE them away. Physics texts are invaluable as references, even after taking a class, which is why most physicists have stacks of them- we can't remember how to do everything we've ever learned, but a little reminder goes a long way.
The vast majority of the recommendations here are top notch. A lot of which book to use really is personal preference and background. Here are my personal choices after having been in 3 separate Physics departments. Also, you should consider looking at ANY of the Landau-Lifshitz texts. These Soviet scientists wrote comprehensive texts that might be right up your alley as someone with a math background. I only wish I could understand them more, their physics is really beautiful.
First off, a general reference book. I recommend the Halliday and Resnick series. Buy this used. It is basically an encyclopedia of physics that is presented at the intro undergraduate level. I use it frequently when working through problems outside my specific area of expertise.
Electricity and Magnetism: Three books. Griffiths, Purcell, and Jackson. The first is a classic undergrad text, the second is a more advanced undergrad text, and the last is the standard graduate text in E&M.
Quantum Mechanics: Griffiths' undergrad text is a must, though it is not very mathematically rigorous. I recommend Shankar as a supplement- Shankar is used as both a grad and undergrad text. I'm an experimentalist who stopped learning formal quantum mechanics after 1 year of graduate study, so Shankar may not be enough for you depending on your interests. Check out other's recommendations. Griffiths and Shankar are very good intro and reference books.
Statistical Mechanics- I used Kittel and Kroemer as an undergrad, and it's OK, a little dated. Huang was my grad text, and it is also OK. I don't have strong feelings here. Landau and Lifshitz may be better for you
Classical Mechanics- Marion and Thorton was my undergrad text. Personally, I don't think the CM text really matters. They are all equally bad. The basics they teach you are what a Langrangian is, and unfortunately always underemphasized what a Hamiltonian is (used REPEATEDLY in QM).
Finally, make sure to get a good Mathematical Methods book, even if you really understand math well (I am sure you do). I recommend Arfken as a reference tome, and the Schaum's outline as a handy desktop reference for solving various partial differential equations. Past that, you should be able to pick up texts cheap used from fellow students, or on eBay. Good luck!
Lol. I have to say, chances are that it was not a particularly difficult topic that was being presented, as much as a particularly poor presentation. Physicists are usually not very good at explaining what they do to students (sad).
This is only true if you are using off-the-shelf parts from companies like Bruker and Varian. My spectrometer is made by Tecmag, and the rest of my setup is home-built. I don't care if the center frequency shifts or not- it'll do that with or without He fills. And the lineshape changes too- that's what shims are for. Also, I don't bother with tuning because for me, the logistics of tuning after each cryogen fill or sample change are impossible, and I'd never acquire any data. In general, I am not very interested in doing super high-res NMR- my setup is originally designed to do microMRI where shifts on the order of a few ppb just don't matter. All those changes get washed out when your start turning on gradients and frequency/phase encoding. That being said, my shifts are no where near as big as yours. At least 200 times smaller.
Because circulating electrons generate a magnetic field, and in the whole time I have maintained this magnet, the field has not changed.
I know because the magnetic field they create has not changed.
The inductive losses should be zero if it is a DC current. I believe this to be true because I have a 7 Tesla SC magnet that has the same electrons running around inside of it that it did over 8 years ago. The only thing I have done to maintain this current is add liquid helium twice a year (it boils off) and liquid nitrogen every week. The liquid helium costs about 400-500 bucks a year, and the LN2 is virtually free- I use maybe 40 or 50 L a week, so over a year, that is MAYBE a thousand bucks, if even that. It is so inexpensive (cheaper than pop) that we don't pay for it out of our research group's funds, our department or perhaps the University just subsidizes it.
Moon River... wider than a mile... I'm crossing you in style some day.
Yes, the pre-Nebula Award SFHoF vol.1 is perhaps the greatest selection of sci-fi short stories ever put together. No author has more than one entry in the book, so you get exposed to a wide swath of different writers. Look for it on eBay!
Instantaneously slashdotted site?
Yet another temperature scale: 70 degrees Delisle = 128 degrees Fahrenheit. They like it hot hot hot!
The ultimate future of solid state lighting resides in a combination of two existing/developing technologies. The first is the LED, already in commercial production, which will continue to be refined with respect to spectral output. The second is a technology that is mostly still in the lab- visible spectrum photonic bandgap materials. Basically, these are kind of "perfect reflectors". By creating an LED in a photonic bandgap material, reabsorption of emitted photons would be eliminated, or at the very least steeply curbed. This would increase the effective efficiency of the LED, giving you more light for the same amount of electrical energy. It would make lighting incredibly inexpensive with regards to energy usage, but the when the combination of LEDs and PBG materials comes out, it will be very expensive, just as with any new technology. It will eventually prove superior to other lighting paradigms due to longevity (how often do LEDs burn out?) and operational costs, especially for industrial users whose premises use a lot of light 24 hours a day.
I don't understand this Slashdot and in general, IT personnel, infatuation with Ron Paul. He is really just the Republican version of Dennis Kucinich in the sense that both are kooky extremists who bring up good points, but in the end are too far too the left and right to be suitable to lead this country. And as for Ron Paul sticking to his guns... why is so much value attached to that? It can be looked at as a foible as well as a virtue. All in all, I think that Ron Paul more poorly represents geeks than many of them realize.
I digress. My plans as president. Hmmm. So many things... well first off, I believe in nationalizing education. We are falling behind other countries very quickly, and without a strong lead in technology, our economy is doomed to fail. I've seen numerous state boards of education fuck up their states' curricula, especially with regards to science, so I think state control, and even more importantly, local community control causes way more harm than good. Plus, as an Ohioan, I can see that funding schools via property taxes is an abject failure, and encourages poor, ignorant people to stay poor and ignorant. Nationalizing education gets us off the property tax crack, or whatever other funding schemes various states/municipalities have in place. We need to all be on the same page, learning the same material. Is science really different in Texas and Kansas than it is in New York or Oregon? Last time I checked, no, but it is taught differently (see evolution), which is crap. We also need to have national standards for teachers. Basically, there is an overabundance of shitfucks in our public schools, who partied hardy and got shitty grades in college, so they became teachers. That's not always true, and there are many good, if not great teachers out there, but they tend to congregate in the better school systems (see funding issues above) because they don't want to deal with the problems associated with poor, ignorant people's kids, as well as the shittier pay. We need to set higher standards and requirements for K-12 teachers, and provide economic incentives to encourage qualified people to enter the teaching profession and meet those goals.
Secondly, I would nationalize health care. It makes little sense to have a private industry provide something that EVERYBODY needs. It takes away the maximum advantages of economy of scale. I am not saying that there is not room for private health care, there still would be. But doctors should be forced to work at set prices, determined by local cost of living, that is paid out by the federal government. If they don't like those set prices, they are free to go out on their own and charge what they will to whomever is willing to pay for it. But otherwise, they get paid by the feds. And there definitely needs to be more accountability on the part of doctors- they should not be financially rewarded for screwing up by getting paid for a second operation or procedure. Financial incentives should be provided for more GPs, and for more doctors period in rural areas, or those working in high-traffic urban hospitals. Will this lower pay for doctors? Probably, but that is not necessarily a bad thing, unless you're a doctor. And to be honest, doctors are overrated, and have an overly large sense of importance. They are basically mechanics for the human body, with good memories, and good hands if they are a surgeon. In my opinion, that should not be worth more than being an innovative scientist or engineer. And don't give me this bullshit about the time doctors spend in med school and residency, etc. Try getting a PhD in science, followed by a post doc, maybe a government lab position, then trying to climb up the tenure track ladder, all to be rewarded by a salary that may not even clear six figures when you are in your early 50's. There is no reason for medical doctors and science/engineering doctorates to have such a large difference in their pay. It is economically wasteful to be paying bio-mechanics that much.
Or if I can't make each breath you take illegal, I at least want a 5-cent royalty. I figure I should be a trillionaire by noon.
Where the energy gets deposited depends on the composition. For instance, an icy asteroid is more likely to deposit energy in the atmosphere as the ice it is partially made up of melts, vaporizes, or perhaps even sublimes. The latent heat of vaporization of water is much much less than that of rock, so a mostly rock asteroid is more likely to stay intact by the time it reaches the surface, hence depositing more of its initial energy into the surface and lower atmostphere.
It seems that while the asteroid itself did not cause as much damage as previously believed (3-5 megatons vs 10-20), the asteroid was most likely much smaller than had been estimated. Too bad the article doesn't give some numbers about the size. Pretty scary thinking about one of these things hitting on top of or near a major population center.
I would say this- the transistor led to virtually all modern electronics. In fact, it is the basis of our modern life and economy. Without it, we could not possibly be where we are today. While tubes may indeed have been the size of the original transistor in 1947/1948, there is no way it could have miniaturized at the rate transistors have- in fact, there is most likely a hard limit to the smallest tube size. Finally, the transistors importance over tubes was that it acted as a miniaturized amplifier. Its true value lay in its ability to facilitate digital (Boolean) logic, which led us to develop computers. The transistor is the single-most important invention of the human race in the last 100 years, and perhaps even the last 200 (though good arguments could be made for penicillin/antibiotics).
Well, so one would think. Unfortunately, there is a fairly hard limit to lowering diffusion via temperature, which is that water freezes at 0C. Once you have a solid, NMR/MRI becomes much more difficult- relaxation times decrease by orders of magnitude (no more motional narrowing), causing short-lived signal and broad linewidths. And even lowering the temperature to just above freezing will only nominally change the diffusion coefficient, probably not more than a factor of 5 or so.
There are hard limits to resolution. You mentioned one in the SNR issue. But you signal average till kingdom come to get around that. Another issue is that at very small voxel sizes, diffusion becomes important, and you get blurring in your image as a result. Understanding how important this is depends on the tissue type, of which I am not an expert (I am not a clinical MRI guy, but a research and development type). BTW, the SNR enhancement from stronger fields goes roughly as the square of the field, so doing these same scans in a 7 Tesla scanner, all other things being equal (which they wouldn't be), would increase the SNR by over 50,000. That is using a 30 mT field, skipping over the 46 microTesla detection field. Honestly, they might be better off trying to do PEDRI, and excite electron resonances, and then couple to the protons via the Overhauser effect to improve their SNR at the higher field. Basically reverse what they are doing now- excite at 46 microT, and detect at 30mT. Or even polarize at 30mT, excite electrons at 46microT, and detect at 30mT. The higher field affects both the net polarization of the spins AND the sensitivity of the detection coils, which is why you'd want to come back to 46 mT. Of course, I am not thinking of using SQUIDS, but more conventional style coils...
From having read the article and comments here, I'd like to make some observations. First off, it seems like there is a very sizable percentage of Slashdot posters who are in the IT community. My anecdotal evidence about IT people is that some of them have this anti-education bias, in that they themselves did not seek out higher education or post-graduate degrees, and have done just fine, which means that they didn't need that higher education. Therefore, higher education is bunk, because you don't need it be successful. I definitely do not agree with that, because basically in the hard sciences, you go nowhere without your PhD.
The other observation I have made is that there is a tendency to look at IT people as being part of this "tech class" that includes scientists and engineers. To me, you need to make a clear distinction, because doing IT is very different than working as an engineer or as a research scientist. You simply don't need the same type of education because you don't do a similar type of job. Yet business pundits often times approach the problem and invoke IT job numbers, which are pretty much irrelevant to science and engineering.
I am in Physics. Half of the graduate students in my department are foreign, mostly from East Asia. I can tell you right now that that has more to do with the lack of domestic talent than the quality of that talent- in other words, there are still not enough domestic physics majors. And it is not that we are trying to attract foreign talent because they are willing to work for less. A friend of mine who is an international student just got a job offer from a well-known tech company that is close to 6 figures. That doesn't sound like peanuts to me. The problem is that as high as that sounds, it may not be high enough. Science and engineering pay better than many jobs, but they do not pay enough to encourage more domestic students to study those fields in college and then go on to get jobs. And while the American public may think it is hunky-dory to pay a PhD physicist 75K a year to do his job, I can assure you that it is not OK. For some reason, Americans are willing to pay doctors hundreds of thousands of dollars a year, but a comparably-educated scientist gets to be merely middle-class, despite working longer hours.
To sum it up, scientists are underpaid, underappreciated, and well-below the national numbers necessary to ensure our continued technological dominance over other countries. Business people are cheap, and usually know next to nothing when it comes to science, and their advice should not be taken seriously, even with a boulder of salt. Business is what engineers who can't cut it in undergrad go into, so there are people there who are jaded against S&E to begin with (not that there are huge numbers, but I think most people who went to college know someone who fits this description). They are looking to cut costs, and one way to do that is disparage scientists and engineers, who as professionals, are not cheap to employ. Unfortunately, what they are being paid right now is STILL not enough, so businesses that employ them are in fact getting a great deal. If American business become convinced that we do not need more scientists and engineers, we are all screwed. An undereducated populace is guaranteed to lose money as jobs that don't involve their heads go the way of the horse and buggy, or even more likely, go overseas.
Please do not watch this show. It is utter crap. I'm a grad student in physics, and am offended by the stereotypes it portrays. Sure, I'm a geek, as evidenced by me posting here. But I also like to have fun, know how to socialize, have had many many relationships with the opposite sex that for the most part have been positive, and basically am known for my personality rather than my career choice, JUST LIKE MOST NORMAL PEOPLE. Oh, and I really hate most Star Trek related things. I did enjoy (but am not a psychotic fan of) the original series (more for its campiness and originality), as well as the 2nd-4th movies. And I like Star Wars, just like any other red-blooded American male who was a little kid in the early 1980's. But that's it. Also, I love sports. Especially baseball, which for some reason seems to be common among physicists (maybe it's all those statistics). Put me in a bar on a fall Saturday or Sunday with football on the TV and I'm happy. Why can't physicists be portrayed for what we really are, which is normal people who happen to do physics? Look at Einstein! Witty, charismatic, and womanizer! Now that's a physicist!
Well, shitty for Wheel of Time fans, Robert Jordan is dead. Looks like you'll never know what happens to the characters. Oh wait, you wouldn't have anyways. Rumor has it that the twelfth and final book had most of the main characters discussing what to have for dinner for more than 35 chapters.
It's like a wealthy financier trying to become a world-renowned filmmaker just because he has the money to hire a camera crew.
Um.... you mean like Howard Hughes? I guess he was pretty good at it after all.I disagree with you on this particular point. Yes it is true that you don't want to water things down. But if you are serious about advocating these particular examples, I believe that you are wrong. I know this because, A. I have solved the hydrogen atom starting from the Schrodinger equation, and B. because I have taught high school science in the US, specifically physics, to 15 and 16 year old children of all kinds of ability levels.
The fact of the matter is that while that may have been OK for you to have studied at the age, it most certainly is NOT for the overwhelming majority of students, by which I mean 99.9%. That is a literal number, not figurative. I myself would have been unable to understand the quantum mechanical derivation of the Bohr model of the atom at the age of 16, even if someone had carefully explained it to me. There is just no way to do that and impart deep understanding of both the process and the end result. You are better off just presenting the solution, because that at least is something that students can understand. 16 year olds (again, 99.9% of them) are not going to understand calculus (did I mention it is multivariable vector calculus in 3 dimensions?), let alone partial differential equations (e.g. Schrodinger) and spherical harmonics, all of which are needed to understand the "walkthrough".
Basically what I am saying is that it is unrealistic to expect even a minority of students to understand such high level concepts that they are not taught in the United States until the sophomore and junior years of university, and even then only to a select number of students (in physics, electrical engineering, and maybe a few others). That is a good way to turn students off to science- making the barrier unnecessarily high. Sometimes, it is OK to gloss over the math, because there is nothing to be gained there. Most students, even the bright ones, are not going to be come physicists, so why subject them to something that is so specific?
Doing a derivation on something like circular motion is much more appropriate. Why? Because it is something that students can relate to (they have all experienced circular motion, centripetal force etc.), unlike quantum mechanics which is inherently non-intuitive, and the math is orders of magnitude simpler (algebra vs spherical harmonics). On that point I am in agreement. But you must be careful about how you phrase your argument and present your viewpoint because the minute you start spouting off about showing students how to derive the Bohr model of the atom from the Schrodinger equation, you are going to turn people because they don't even know what the Schrodinger equation is. We don't want to dumb down science, but at the same time it needs to be accessible to students beyond the future Stephen Hawkings of the world.