I mean it basically seems to be saying that if I have a meter stick which is the "standard", and you have a meter stick that's twice as long, and in the middle of the night you sneak in to the building where the meter stick is kept, that the next day nobody would be able to tell the difference.
Sort of. More to the point, suppose that the fine structure constant changes overnight. Then the meter stick is going to shrink or expand because its size is determined by electromagnetic interactions, and the fine structure constant is a way of parametrizing the strength of those interactions.
All of it makes me wonder what the mechanism is that determines c or the gravitational constant, the electro weak force and a myriad of other variables that determine the way the universe exists
All of the quantities you've listed have units, and therefore what determines them is our choice of a system of units. What makes sense is to ask what determines unitless constants such as the fine structure constant. Here is a nice discussion of this kind of thing: http://math.ucr.edu/home/baez/constants.html
First off, the slashdot summary is somewhat misleading, because the result is not new. Their result was announced in August 2010: http://arxiv.org/abs/1008.3907 . What is new is that they finally managed to get it published in a peer-reviewed journal. You can't judge whether it's right or wrong simply based on whether it's been published in a peer-reviewed journal. Peer review doesn't judge whether a result is right, or whether it can be reproduced. Peer review just tries to judge whether there are obvious mistakes, and things like whether it properly cites the previous literature. The fact that the journal is a prestigious one also doesn't mean it's right; it just means that *if* it were right, it would be of a high level of scientific importance.
Second, it's not really correct to say that the result is controversial. It's not controversial. It's wrong, and the fact that it's wrong is uncontroversial. Just because there's an overwhelming consensus that a result is wrong, that doesn't mean it can't be published in a peer-reviewed journal. Below is a FAQ entry I wrote about this stuff.
Has the fine structure constant changed over cosmological timescales?
It has been claimed based on astronomical observations that the unitless fine-structure constant alpha=e^2/hbar*c actually varies over time, rather than being fixed.[Webb 2001] This claim is probably wrong, since later attempts to reproduce the observations failed.[Chand 2004] Rosenband et al.[Rosenband 2008] have done laboratory measurements that rule out a linear decrease of alpha with time large enough to be consistent with Webb's results.
Webb et al. have recently made even more extraordinary claims that the fine structure constant varies over the celestial sphere.[Webb 2010] Extraordinary claims require extraordinary proof, and Webb et al. have not supplied that; their results are at the margins of statistical significance compared to their random and systematic errors.
Even if their claims are correct, this is not evidence that c is changing, as is sometimes stated in the popular press. If an experiment is to test whether a fundamental constant is really constant, the constant must be unitless.[Duff 2002] If the fine-structure constant does vary, there is no empirical way to assign blame to c as opposed to hbar or e. John Baez has a nice web page discussing the unitless constants of nature.
if we assume that only muon neutrinos are tachyonic, there's a trivial explanation
This possibility has been investigated, and it doesn't work: if different neutrino flavors had different limiting velocities of propagation, then neutrino oscillations would go away when the neutrinos propagated over long distances, because the wave-packets would split up. http://arxiv.org/abs/1109.5682 This is contrary to previous observations.
This is helpful but not that helpful. There are at this point a variety of potential explanations for what went wrong in the OPERA experiment. These include mismeasuring the tunnel length, issues with the clock calibration, and issues with the statistical analysis among other issues.
The distance measurement and clock calibration were initially proposed by people outside the calibration as simple explanations, but at this point it's clear that they are simply not credible explanations. Contaldi http://arxiv.org/abs/1109.6160
suggested early on that the clocks could have been put out of synchronization by transport, but the OPERA team clarified that they were calibrated after
transport, through GPS. Van Elburg, who is apparently completely ignorant of how GPS works, proposed that it could be a special-relativistic
time dilation effect due to the orbital motion of GPS satellites relative to the lab frame. The distance measurement would have to be off by 20 meters in order to explain the
60 ns shift, and that's completely implausible.
All of the really obvious, stupid explanations have been ruled out -- which is not a big surprise, since 170 PhD's in the OPERA collaboration had
their reputations on the line, so they were highly motivated to detect any really dumb blunders. So the remaining sources of error really are things in the general
category you're referring to as statistical analysis. Some serious suggestions have been made that seem viable: (1) There could be a correlation between the direction of emission
of the neutrinos and the time at which they were emitted during the 10 us beam pulse. (2) There could be a correlation between the distribution of
energies in the neutrino beam and the time of emission. (3) There could be spillover from previous beam pulses. (4) There could be subtle effects in the
electronics such as dead-time. Every single one of these possible errors is eliminated in the design that they're currently running, with 1- or 2-ns pulses instead of 10 us ones.
A better replication attempt is that which is being done by MINOS http://en.wikipedia.org/wiki/MINOS [wikipedia.org], the equivalent experiment at Fermilab in the US. One reason that OPERA was paying careful attention to the arrival times (when their main interest was actually in measuring neutrino oscillation) was that MINOS had earlier reported data that tentatively suggested that some neutrinos might be going too fast. Now that OPERA has done their work, MINOS is working on doing a more detailed analysis that should be out by around February.
The trouble with MINOS is that (1) they have poorer statistics, (2) the energy is lower than the one used in CNGS (and the FTL effect,
if real, is energy-dependent), and (3) OPERA's design was closely based on MINOS's, so
subtle sources of error that are present in OPERA are likely to be present in MINOS as well. A better candidate for totally independent checking of the OPERA
result is Tokai to Kamioka (T2K).
But, if the neutrinos traveled faster than light to the extent OPERA data suggests then SN 1987A neutrinos should have arrived years earlier.
If you believe both the OPERA result and other results at lower energy, then there is an energy-dependence in the speed that is different than that predicted by special relativity.
(If neutrinos were tachyons, which is consistent with SR, then OPERA neutrinos would have been slower than SN1987A neutrinos, because tachyons go
slower when you put more energy in them. This is the opposite of what is actually claimed observationally.)
There is essentially no hope for reconciling this observation with theory, unless we are in the middle of a major scientific revolution where everything is so weird that we just can't
make sense of it yet -- which I don't find plausible. If neutrinos really went faster than light, then they would emit
I have yet to meet the piece of paper that gives immediate feedback.
Here's an example. The following is written on a piece of paper:
Divide 7 by 11, expressing your result as a repeating decimal. Check your answer by multiplication.
Immediate feedback is provided by the part about checking your answer.
Parent post:
Oh pooh. Real life problems don't come with pre-programmed immediate answers. Immediate feedback encourages trail and error problem solving rather than thinking through the answers, and is very harmful.
Well, yes and no. It is certainly possible to construct tasks that can't be done by trial and error. As an example from the college level, I assign a physics homework problem where the answer is T=(1/2)Mg(1+(L/2h)^2)^(1/2). What do you think are the chances that someone is going to come up with that formula by chance? I use computer software that allows students to check the answer. One of the advantages of the software is that if they come up with some equivalent form, such as Mg/2sin(atan(h/L)), the software can immediately recognize it as being correct. (The software checks for equality by plugging in random numbers for M, g, L, and h, and seeing if it gets the same answer from both forms. This doesn't rigorously prove that the two forms are equivalent, but in the practical examples we do in my class, it turns out to be 100% accurate.)
I certainly do see students try to do problems by random guessing, and some of the problems I assign are doable by random guessing. Well, hey, there are lots of dopey things students do. All you can do is try to give them guidance and hope they accept it.
Computers are not inherently good or bad -- not in education, and not anywhere else. They're a tool. Tools can be used correctly or incorrectly.
Poorer schools often have terrible teacher to student ratios[...]
The school they're describing is in California. My kids go to public schools in California, and I don't think what you're saying is accurate. In the late 90's/early 2000's, California went through a period where the economy was good, and we got class size reduction. It was state-mandated, e.g., they decided that in K-2 or whatever they would have a maximum student-to-teacher ratio of x. Then the economy turned sour, and they started laying off teachers and increasing class sizes again. Our school district is affluent, and it has some very highly ranked schools. However, my kids are experiencing the same extremely large class sizes as everyone else in California.
IIRC, research also shows that class size does not have any empirically measurable effect on learning until you get it down to about 10 -- which isn't going to happen in any public school.
It's true that in the US, when schools draw from a population with low socioeconomic status, those schools are almost always horrible by all the available objective measures. However, I'm really not convinced that that has all that much to do with funding and class size. I think it's overwhelmingly a "network effect," similar to the network effect that makes Windows so popular. The parents have low levels of education, don't have books in the house, don't subscribe to a newspaper, and don't have high educational expectations for their kids. Many of them may be immigrants, and their kids may come into school with low English skills. The teachers are there because they couldn't get a job in a better school district. Incompetent teachers probably won't be fired (because of teachers' unions), and even if they were, there is no particular reason to believe that the school would be able to attract a replacement candidate who was any better. Families that have enough money to have a choice will choose to live in a better school district. Kids model their behavior on their peers'. They see that 60% of their peers don't do their homework. There isn't enough critical mass of kids to do geekly things like a chess club or a model rocket club. None of this changes if you just put more money, computers, etc., into the school.
(Interestingly, the anti-nukes just HATE this, and severely critisize us for using such a deceptive concept.)
Well, that might actually be because you have your facts wrong. BTW, I have a PhD in physics, my specialty is nuclear physics, I am very much in favor of nuclear power, and I think the radiation issues at Fukushima were ridiculously overblown. But nevertheless that doesn't affect the reality that your facts are wrong.
The body has systems that regulate the amount of potassium it holds. If you ingest more potassium, your body immediately detects that and immediately excretes the excess in your urine. Therefore ingesting a banana has essentially no effect on your radiation exposure. For a very short time, you have a slightly higher than normal amount of potassium in your body. Then it goes back down. The integrated excess dose turns out to be negligible compared to natural background.
If you want an example that's scientifically correct, here are some:
sleeping in the same bed as someone else for one month =.001 mSv (not that this will be an issue for slashdotters)
eating a pound of Brazil nuts =.001 mSv
long plane flight =.1 mSv
CT scan = 10 mSv
dose needed to cause mild radiation sickness = 1000 mSv in a short time
maximum excess rate of exposure for people in Tokyo due to Fukushima =.001 mSv/hr
I'm not a Republican or a Democrat, so I have very few meaningful ways of participating in the US political process. My congressman is a social-conservative Republican in a safe Republican district, so there is essentially no chance of ever getting rid of him. I did recently re-register Republican so that I could vote against him twice, once in the primary and once in the general election -- not that it will accomplish anything. Another benefit of being registered Republican is that I can vote against Rick Perry in the primary. And that's about it -- that's all I can do in electoral politics, and it ain't much. I'd love to have a chance to vote for a politician who was against the USA-PATRIOT Act, but I can't, because it has essentially 100% support in both of the major parties. Ditto for ending the disastrous War on Drugs, or for kicking America's habit of getting involved in multiple simultaneous wars thousands of miles away from home; all of these issues have zero traction in either of the two major parties.
So this petition thing may not be much, but I'll take what I can get. It might make it harder for politicians to claim that absolutely nobody cares about certain issues, and that would be a good thing.
...I would support elimination of DOE. DOE does a random collection of stuff. One of the things it does is support physics research, which is what I was doing -- it sort of plays the same role as NSF does in the life sciences. The thing that most non-scientists don't understand about science is that the vast majority of scientific papers are both (a) correct and (b) utterly unimportant. Researchers get tenure or permanent jobs by publishing as many papers as possible. Quality matters, but quantity is also mandatory. Because DOE does so many different things, I can't comment from personal experience on all of them, but I would be 100% in favor of closing the DOE lab (Argonne National Lab) where I worked. It would have absolutely no impact on the amount of important new scientific discoveries coming out, only on the number of scientific papers coming out. There is really sort of a conservation law at work in science. At any given time iin history, scientific techniques are capable of doing certain things, and people will use those techniques to do the obvious, important things. If you hire ten times more scientists, they'll just continue using that technique to do more of the same.
I currently work in education, and I would say ditto for the department of education. I teach at a community college, and we get 100% of our funding from state and local taxes. Education is not a traditional or proper field for the federal government to be involved in. The federal government does fund research at universities, but that's not education, it's research. (Yes, the two do overlap, but only partially.) If we ever needed a demonstration of what can go wrong when the feds get involved in education, NCLB was it.
Does this mean that we're in a Godel Universe, and that closed timelike loops are possible?
No. The Godel metric has rotation and closed timelike curves, but not all cosmological solutions that have rotation have CTCs. The Godel universe is not consistent with observation. For descriptions of some cosmological models that have rotation but no CTCs, see the references here: http://physicsforums.com/showthread.php?t=506988
So we still can't say objectively that the universe is spinning.
No, if this result is correct then we can say the universe is spinning. FAQ
Although, this outwards acceleration could possibly explain the expansion of the universe (instead of "dark energy").
The upper bounds on the universe's rate of rotation are such that it cannot have any significant contribution to the universe's expansion. (See the references in the FAQ link above.)
There's nothing intrinsically wrong with the idea. It's perfectly consistent with all the known laws of physics. There is in fact no well-established physical principle that should make non-rotation any more likely than rotation. There are other techniques for detecting rotation of the universe (see the references in the FAQ entry); their claim would become much more convincing if it could be confirmed by one of those techniques.
If it's right, then it probably implies that inflation was an incorrect theory; I believe that in cosmological models that include both rotation and inflation, the angular velocity dies out exponentially, so it should be unobservably small today.
When you use a surveying-quality GPS in a fixed position over a long period, it is much, much more accurate than a hand-held or car-mounted GPS. It has two channels, which allows it to correct for ionospheric distortion. Echoes from cliffs and tall buildings cause intermittent errors on hand-held GPS, when the satellite geometry is unfavorable, but I don't think they're an issue here. There is a graph in the OPERA group's paper where they show the GPS detecting the 6-cm shift when an earthquake occurred in Italy.
Looking back at this post, I notice one thing I said that was an oversimplification. The ECI t coordinate does differ from a time coordinate synchronized in the frame of the labs, which are rotating with the earth. However, the relative velocity involved is the velocity of the earth's rotation, not the much larger orbital velocity of the satellites, which is what van Elburg assumed was relevant. The effect is vx/c^2, where x is the east-west distance between the two labs. If you work it out, it's less than one ns, which is far too small to be relevant. (I assume OPERA did understand this issue and take it into account, but even if they hadn't, it would be far too small to explain the effect.)
It's bogus. (Yes, I am a physicist.) OPERA used portable atomic clocks, which were moved to the the two labs and then synchronized via GPS (see this article). GPS thoroughly incorporates general relativity (which includes special relativity). It has incorporated GR ever since it was first built, because if it didn't, it wouldn't work. At all. No, not even well enough for hiking and driving. Here is a review article on relativity in GPS. GPS uses coordinates called Earth-Centered Inertial (ECI). These are coordinates (t,r,theta,phi), where the spatial coordinates are spherical coordinates that rotate along with the earth, and t is the time coordinate of a hypothetical observer in a nonrotating frame at rest relative to the center of the earth. General relativity is completely agnostic about what coordinate system you use, so this choice of a coordinate system is not a choice that has any physical significance; it's just a bookkeeping thing. Van Elburg assumes that GPS was constructed by people who didn't understand relativity, and therefore GPS times need to be corrected for relativistic effects. That's just completely wrong.
if the priest's superior knows that his priest-employee has been looking at kiddie porn for 30 years with no instances of abuse, then he can come to a reasonable conclusion that he won't abuse.
"In a memo dated May 19, 2010, Hess wrote that several people had complained Ratigan was taking compromising pictures of young children and that he allowed them to sit on his lap and reach into his pocket for candy."
The problem is, the law is ordering you to ruin someone's career and life when no one has been harmed,[...]
If the porn is a cartoon drawing, then probably no child has been harmed. But that wasn't the case here. "Seven months later, a computer technician working on Ratigan's laptop found hundreds of what he called "disturbing" images of children, most of them fully clothed with the focus on their crotch areas, and a series of pictures of a 2- to 3-year-old girl with her genitals exposed." If someone took crotch shots of my daughter when she was 2, I would certainly consider that "harm."
Yes, but once you have no copyright restrictions at all, then no book is even slightly profitable (at least for the author)..
Two misconceptions here: (1) Copyleft is not the same as having no copyright restrictions at all. Copyleft means using a license such as CC-BY-SA. (2) Copyleft is not incompatible with profit. My own physics textbooks, for example, are copylefted and profitable for me. (I make money from ads on my web site, but other authors of copylefted books have other ways of making a buck.)
I run a site that catalogs books that have intentionally been made free by their authors (see my sig). By far the majority of such books are just free-as-in-beer, not free-as-in-speech.
The half-life of the free-as-in-beer books seems to be something like 5 years. That's about how long it typically takes before the author takes them down off the web, and they are lost forever. (This is not just like a printed book going out of print. These books are typically not sitting around in libraries. That means they're as lost as a lost play by Aristophanes.)
Free-as-in-beer books are different. The beautiful thing about copyleft licensing is that once you provide the world with the gift of a piece of copylefted information, it's free forever. It basically doesn't matter at all that Mark Pilgrim has taken down his web site. Because his books are free-as-in-speech, his valuable contributions to the digital commons are still out there, making people's lives better.
We would all be a lot richer if more people could be convinced of what a good thing copyleft licenses are. When it comes to books, the problem seems to be that people underestimate how hard it is to do commercially successful writing. They have this illusion that they're going to make all kinds of money from their wonderful book, and they see copyleft licensing as being incompatible with that. The hard truth is that even a good, well-written book is seldom significantly profitable.
The right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures, shall not be violated, and no Warrants shall issue, but upon probable cause, supported by Oath or affirmation, and particularly describing the place to be searched, and the persons or things to be seized.
What about that is so complicated that the courts and the governor can't understand it? A cellphone is an effect and the Bill of rights says you need a warrant to search those. It offers no exceptions.
I think there are some parts that you're not understanding. There's the part about "unreasonable." If you get arrested, in any state of the union, the cops are almost certainly going to search you to see if you have a knife or a gun on you, and they're going to take away your wallet while you're in jail. This is not unconstitutional. If you want to argue that pawing around on someone's cell phone is constitutionally distinct from searching their pockets and removing their contents, then please feel free to do that. You just haven't done that yet.
Slashdot Mirror
I mean it basically seems to be saying that if I have a meter stick which is the "standard", and you have a meter stick that's twice as long, and in the middle of the night you sneak in to the building where the meter stick is kept, that the next day nobody would be able to tell the difference.
Sort of. More to the point, suppose that the fine structure constant changes overnight. Then the meter stick is going to shrink or expand because its size is determined by electromagnetic interactions, and the fine structure constant is a way of parametrizing the strength of those interactions.
All of it makes me wonder what the mechanism is that determines c or the gravitational constant, the electro weak force and a myriad of other variables that determine the way the universe exists
All of the quantities you've listed have units, and therefore what determines them is our choice of a system of units. What makes sense is to ask what determines unitless constants such as the fine structure constant. Here is a nice discussion of this kind of thing: http://math.ucr.edu/home/baez/constants.html
The AC is basically right. Here are a couple of careful discussions of this topic: http://arxiv.org/abs/hep-th/0208093 , http://math.ucr.edu/home/baez/constants.html
First off, the slashdot summary is somewhat misleading, because the result is not new. Their result was announced in August 2010: http://arxiv.org/abs/1008.3907 . What is new is that they finally managed to get it published in a peer-reviewed journal. You can't judge whether it's right or wrong simply based on whether it's been published in a peer-reviewed journal. Peer review doesn't judge whether a result is right, or whether it can be reproduced. Peer review just tries to judge whether there are obvious mistakes, and things like whether it properly cites the previous literature. The fact that the journal is a prestigious one also doesn't mean it's right; it just means that *if* it were right, it would be of a high level of scientific importance.
Second, it's not really correct to say that the result is controversial. It's not controversial. It's wrong, and the fact that it's wrong is uncontroversial. Just because there's an overwhelming consensus that a result is wrong, that doesn't mean it can't be published in a peer-reviewed journal. Below is a FAQ entry I wrote about this stuff.
Has the fine structure constant changed over cosmological timescales?
It has been claimed based on astronomical observations that the unitless fine-structure constant alpha=e^2/hbar*c actually varies over time, rather than being fixed.[Webb 2001] This claim is probably wrong, since later attempts to reproduce the observations failed.[Chand 2004] Rosenband et al.[Rosenband 2008] have done laboratory measurements that rule out a linear decrease of alpha with time large enough to be consistent with Webb's results.
Webb et al. have recently made even more extraordinary claims that the fine structure constant varies over the celestial sphere.[Webb 2010] Extraordinary claims require extraordinary proof, and Webb et al. have not supplied that; their results are at the margins of statistical significance compared to their random and systematic errors.
Even if their claims are correct, this is not evidence that c is changing, as is sometimes stated in the popular press. If an experiment is to test whether a fundamental constant is really constant, the constant must be unitless.[Duff 2002] If the fine-structure constant does vary, there is no empirical way to assign blame to c as opposed to hbar or e. John Baez has a nice web page discussing the unitless constants of nature.
J.K. Webb et al., 2000, "Further Evidence for Cosmological Evolution of the Fine Structure Constant," http://arxiv.org/abs/astro-ph/0012539v3
J.K. Webb et al., 2010, "Evidence for spatial variation of the fine structure constant," http://arxiv.org/abs/1008.3907
H. Chand et al., 2004, Astron. Astrophys. 417: 853, http://arxiv.org/abs/astro-ph/0401094
Srianand et al., 2004, Phys.Rev.Lett.92:121302, http://arxiv.org/abs/astro-ph/0402177
Duff, 2002, "Comment on time-variation of fundamental constants," http://arxiv.org/abs/hep-th/0208093
Baez, http://math.ucr.edu/home/baez/constants.html
Rosenband et al., 2008, 319 (5871): 1808-1812, http://www.sciencemag.org/content/319/5871/1808.abstract
if we assume that only muon neutrinos are tachyonic, there's a trivial explanation
This possibility has been investigated, and it doesn't work: if different neutrino flavors had different limiting velocities of propagation, then neutrino oscillations would go away when the neutrinos propagated over long distances, because the wave-packets would split up. http://arxiv.org/abs/1109.5682 This is contrary to previous observations.
GR-based explanations (with or without extra dimensions) have been considered, and they don't work: http://arxiv.org/abs/1109.6312 http://arxiv.org/abs/1109.5687
This is helpful but not that helpful. There are at this point a variety of potential explanations for what went wrong in the OPERA experiment. These include mismeasuring the tunnel length, issues with the clock calibration, and issues with the statistical analysis among other issues.
The distance measurement and clock calibration were initially proposed by people outside the calibration as simple explanations, but at this point it's clear that they are simply not credible explanations. Contaldi http://arxiv.org/abs/1109.6160 suggested early on that the clocks could have been put out of synchronization by transport, but the OPERA team clarified that they were calibrated after transport, through GPS. Van Elburg, who is apparently completely ignorant of how GPS works, proposed that it could be a special-relativistic time dilation effect due to the orbital motion of GPS satellites relative to the lab frame. The distance measurement would have to be off by 20 meters in order to explain the 60 ns shift, and that's completely implausible.
All of the really obvious, stupid explanations have been ruled out -- which is not a big surprise, since 170 PhD's in the OPERA collaboration had their reputations on the line, so they were highly motivated to detect any really dumb blunders. So the remaining sources of error really are things in the general category you're referring to as statistical analysis. Some serious suggestions have been made that seem viable: (1) There could be a correlation between the direction of emission of the neutrinos and the time at which they were emitted during the 10 us beam pulse. (2) There could be a correlation between the distribution of energies in the neutrino beam and the time of emission. (3) There could be spillover from previous beam pulses. (4) There could be subtle effects in the electronics such as dead-time. Every single one of these possible errors is eliminated in the design that they're currently running, with 1- or 2-ns pulses instead of 10 us ones.
A better replication attempt is that which is being done by MINOS http://en.wikipedia.org/wiki/MINOS [wikipedia.org], the equivalent experiment at Fermilab in the US. One reason that OPERA was paying careful attention to the arrival times (when their main interest was actually in measuring neutrino oscillation) was that MINOS had earlier reported data that tentatively suggested that some neutrinos might be going too fast. Now that OPERA has done their work, MINOS is working on doing a more detailed analysis that should be out by around February.
The trouble with MINOS is that (1) they have poorer statistics, (2) the energy is lower than the one used in CNGS (and the FTL effect, if real, is energy-dependent), and (3) OPERA's design was closely based on MINOS's, so subtle sources of error that are present in OPERA are likely to be present in MINOS as well. A better candidate for totally independent checking of the OPERA result is Tokai to Kamioka (T2K).
But, if the neutrinos traveled faster than light to the extent OPERA data suggests then SN 1987A neutrinos should have arrived years earlier.
If you believe both the OPERA result and other results at lower energy, then there is an energy-dependence in the speed that is different than that predicted by special relativity. (If neutrinos were tachyons, which is consistent with SR, then OPERA neutrinos would have been slower than SN1987A neutrinos, because tachyons go slower when you put more energy in them. This is the opposite of what is actually claimed observationally.)
There is essentially no hope for reconciling this observation with theory, unless we are in the middle of a major scientific revolution where everything is so weird that we just can't make sense of it yet -- which I don't find plausible. If neutrinos really went faster than light, then they would emit
GP post:
I have yet to meet the piece of paper that gives immediate feedback.
Here's an example. The following is written on a piece of paper:
Divide 7 by 11, expressing your result as a repeating decimal. Check your answer by multiplication.
Immediate feedback is provided by the part about checking your answer.
Parent post:
Oh pooh. Real life problems don't come with pre-programmed immediate answers. Immediate feedback encourages trail and error problem solving rather than thinking through the answers, and is very harmful.
Well, yes and no. It is certainly possible to construct tasks that can't be done by trial and error. As an example from the college level, I assign a physics homework problem where the answer is T=(1/2)Mg(1+(L/2h)^2)^(1/2). What do you think are the chances that someone is going to come up with that formula by chance? I use computer software that allows students to check the answer. One of the advantages of the software is that if they come up with some equivalent form, such as Mg/2sin(atan(h/L)), the software can immediately recognize it as being correct. (The software checks for equality by plugging in random numbers for M, g, L, and h, and seeing if it gets the same answer from both forms. This doesn't rigorously prove that the two forms are equivalent, but in the practical examples we do in my class, it turns out to be 100% accurate.)
I certainly do see students try to do problems by random guessing, and some of the problems I assign are doable by random guessing. Well, hey, there are lots of dopey things students do. All you can do is try to give them guidance and hope they accept it.
Computers are not inherently good or bad -- not in education, and not anywhere else. They're a tool. Tools can be used correctly or incorrectly.
Poorer schools often have terrible teacher to student ratios[...]
The school they're describing is in California. My kids go to public schools in California, and I don't think what you're saying is accurate. In the late 90's/early 2000's, California went through a period where the economy was good, and we got class size reduction. It was state-mandated, e.g., they decided that in K-2 or whatever they would have a maximum student-to-teacher ratio of x. Then the economy turned sour, and they started laying off teachers and increasing class sizes again. Our school district is affluent, and it has some very highly ranked schools. However, my kids are experiencing the same extremely large class sizes as everyone else in California.
IIRC, research also shows that class size does not have any empirically measurable effect on learning until you get it down to about 10 -- which isn't going to happen in any public school.
It's true that in the US, when schools draw from a population with low socioeconomic status, those schools are almost always horrible by all the available objective measures. However, I'm really not convinced that that has all that much to do with funding and class size. I think it's overwhelmingly a "network effect," similar to the network effect that makes Windows so popular. The parents have low levels of education, don't have books in the house, don't subscribe to a newspaper, and don't have high educational expectations for their kids. Many of them may be immigrants, and their kids may come into school with low English skills. The teachers are there because they couldn't get a job in a better school district. Incompetent teachers probably won't be fired (because of teachers' unions), and even if they were, there is no particular reason to believe that the school would be able to attract a replacement candidate who was any better. Families that have enough money to have a choice will choose to live in a better school district. Kids model their behavior on their peers'. They see that 60% of their peers don't do their homework. There isn't enough critical mass of kids to do geekly things like a chess club or a model rocket club. None of this changes if you just put more money, computers, etc., into the school.
(Interestingly, the anti-nukes just HATE this, and severely critisize us for using such a deceptive concept.)
Well, that might actually be because you have your facts wrong. BTW, I have a PhD in physics, my specialty is nuclear physics, I am very much in favor of nuclear power, and I think the radiation issues at Fukushima were ridiculously overblown. But nevertheless that doesn't affect the reality that your facts are wrong.
The body has systems that regulate the amount of potassium it holds. If you ingest more potassium, your body immediately detects that and immediately excretes the excess in your urine. Therefore ingesting a banana has essentially no effect on your radiation exposure. For a very short time, you have a slightly higher than normal amount of potassium in your body. Then it goes back down. The integrated excess dose turns out to be negligible compared to natural background.
If you want an example that's scientifically correct, here are some:
sleeping in the same bed as someone else for one month = .001 mSv (not that this will be an issue for slashdotters)
eating a pound of Brazil nuts = .001 mSv
long plane flight = .1 mSv
CT scan = 10 mSv
dose needed to cause mild radiation sickness = 1000 mSv in a short time
maximum excess rate of exposure for people in Tokyo due to Fukushima = .001 mSv/hr
I'm not a Republican or a Democrat, so I have very few meaningful ways of participating in the US political process. My congressman is a social-conservative Republican in a safe Republican district, so there is essentially no chance of ever getting rid of him. I did recently re-register Republican so that I could vote against him twice, once in the primary and once in the general election -- not that it will accomplish anything. Another benefit of being registered Republican is that I can vote against Rick Perry in the primary. And that's about it -- that's all I can do in electoral politics, and it ain't much. I'd love to have a chance to vote for a politician who was against the USA-PATRIOT Act, but I can't, because it has essentially 100% support in both of the major parties. Ditto for ending the disastrous War on Drugs, or for kicking America's habit of getting involved in multiple simultaneous wars thousands of miles away from home; all of these issues have zero traction in either of the two major parties.
So this petition thing may not be much, but I'll take what I can get. It might make it harder for politicians to claim that absolutely nobody cares about certain issues, and that would be a good thing.
...I would support elimination of DOE. DOE does a random collection of stuff. One of the things it does is support physics research, which is what I was doing -- it sort of plays the same role as NSF does in the life sciences. The thing that most non-scientists don't understand about science is that the vast majority of scientific papers are both (a) correct and (b) utterly unimportant. Researchers get tenure or permanent jobs by publishing as many papers as possible. Quality matters, but quantity is also mandatory. Because DOE does so many different things, I can't comment from personal experience on all of them, but I would be 100% in favor of closing the DOE lab (Argonne National Lab) where I worked. It would have absolutely no impact on the amount of important new scientific discoveries coming out, only on the number of scientific papers coming out. There is really sort of a conservation law at work in science. At any given time iin history, scientific techniques are capable of doing certain things, and people will use those techniques to do the obvious, important things. If you hire ten times more scientists, they'll just continue using that technique to do more of the same.
I currently work in education, and I would say ditto for the department of education. I teach at a community college, and we get 100% of our funding from state and local taxes. Education is not a traditional or proper field for the federal government to be involved in. The federal government does fund research at universities, but that's not education, it's research. (Yes, the two do overlap, but only partially.) If we ever needed a demonstration of what can go wrong when the feds get involved in education, NCLB was it.
The radius of the observable universe is about 14Gly, not 14Gpc
The radius of the observable universe is about 46 Gly. http://physicsforums.com/showthread.php?t=506987
Does this mean that we're in a Godel Universe, and that closed timelike loops are possible?
No. The Godel metric has rotation and closed timelike curves, but not all cosmological solutions that have rotation have CTCs. The Godel universe is not consistent with observation. For descriptions of some cosmological models that have rotation but no CTCs, see the references here: http://physicsforums.com/showthread.php?t=506988
Okay, so what is the reference frame for the universe, in which you can measure angular momentum, spin, or even velocity (or even origin)?
General relativity doesn't have global frames of reference like the ones in Newtonian mechanics. It only has local ones.
If this result is correct, then there is a uniform vector field that exists throughout space, and objects have a tendency to align with this field.
So we still can't say objectively that the universe is spinning.
No, if this result is correct then we can say the universe is spinning. FAQ
Although, this outwards acceleration could possibly explain the expansion of the universe (instead of "dark energy").
The upper bounds on the universe's rate of rotation are such that it cannot have any significant contribution to the universe's expansion. (See the references in the FAQ link above.)
If the universe spins... what is it spinning in? "Space"?
Does space therefore exist outside the universe (other than in some theoretical brane)?
http://physicsforums.com/showthread.php?t=506988
The actual paper is here: http://arxiv.org/abs/1104.2815
Here is a FAQ entry about rotation of the universe and how general relativity would describe it: http://www.physicsforums.com/showthread.php?t=506988
There's nothing intrinsically wrong with the idea. It's perfectly consistent with all the known laws of physics. There is in fact no well-established physical principle that should make non-rotation any more likely than rotation. There are other techniques for detecting rotation of the universe (see the references in the FAQ entry); their claim would become much more convincing if it could be confirmed by one of those techniques. If it's right, then it probably implies that inflation was an incorrect theory; I believe that in cosmological models that include both rotation and inflation, the angular velocity dies out exponentially, so it should be unobservably small today.
When you use a surveying-quality GPS in a fixed position over a long period, it is much, much more accurate than a hand-held or car-mounted GPS. It has two channels, which allows it to correct for ionospheric distortion. Echoes from cliffs and tall buildings cause intermittent errors on hand-held GPS, when the satellite geometry is unfavorable, but I don't think they're an issue here. There is a graph in the OPERA group's paper where they show the GPS detecting the 6-cm shift when an earthquake occurred in Italy.
Looking back at this post, I notice one thing I said that was an oversimplification. The ECI t coordinate does differ from a time coordinate synchronized in the frame of the labs, which are rotating with the earth. However, the relative velocity involved is the velocity of the earth's rotation, not the much larger orbital velocity of the satellites, which is what van Elburg assumed was relevant. The effect is vx/c^2, where x is the east-west distance between the two labs. If you work it out, it's less than one ns, which is far too small to be relevant. (I assume OPERA did understand this issue and take it into account, but even if they hadn't, it would be far too small to explain the effect.)
It's bogus. (Yes, I am a physicist.) OPERA used portable atomic clocks, which were moved to the the two labs and then synchronized via GPS (see this article). GPS thoroughly incorporates general relativity (which includes special relativity). It has incorporated GR ever since it was first built, because if it didn't, it wouldn't work. At all. No, not even well enough for hiking and driving. Here is a review article on relativity in GPS. GPS uses coordinates called Earth-Centered Inertial (ECI). These are coordinates (t,r,theta,phi), where the spatial coordinates are spherical coordinates that rotate along with the earth, and t is the time coordinate of a hypothetical observer in a nonrotating frame at rest relative to the center of the earth. General relativity is completely agnostic about what coordinate system you use, so this choice of a coordinate system is not a choice that has any physical significance; it's just a bookkeeping thing. Van Elburg assumes that GPS was constructed by people who didn't understand relativity, and therefore GPS times need to be corrected for relativistic effects. That's just completely wrong.
if the priest's superior knows that his priest-employee has been looking at kiddie porn for 30 years with no instances of abuse, then he can come to a reasonable conclusion that he won't abuse.
"In a memo dated May 19, 2010, Hess wrote that several people had complained Ratigan was taking compromising pictures of young children and that he allowed them to sit on his lap and reach into his pocket for candy."
The problem is, the law is ordering you to ruin someone's career and life when no one has been harmed,[...]
If the porn is a cartoon drawing, then probably no child has been harmed. But that wasn't the case here. "Seven months later, a computer technician working on Ratigan's laptop found hundreds of what he called "disturbing" images of children, most of them fully clothed with the focus on their crotch areas, and a series of pictures of a 2- to 3-year-old girl with her genitals exposed." If someone took crotch shots of my daughter when she was 2, I would certainly consider that "harm."
Yes, but once you have no copyright restrictions at all, then no book is even slightly profitable (at least for the author)..
Two misconceptions here: (1) Copyleft is not the same as having no copyright restrictions at all. Copyleft means using a license such as CC-BY-SA. (2) Copyleft is not incompatible with profit. My own physics textbooks, for example, are copylefted and profitable for me. (I make money from ads on my web site, but other authors of copylefted books have other ways of making a buck.)
I run a site that catalogs books that have intentionally been made free by their authors (see my sig). By far the majority of such books are just free-as-in-beer, not free-as-in-speech.
The half-life of the free-as-in-beer books seems to be something like 5 years. That's about how long it typically takes before the author takes them down off the web, and they are lost forever. (This is not just like a printed book going out of print. These books are typically not sitting around in libraries. That means they're as lost as a lost play by Aristophanes.)
Free-as-in-beer books are different. The beautiful thing about copyleft licensing is that once you provide the world with the gift of a piece of copylefted information, it's free forever. It basically doesn't matter at all that Mark Pilgrim has taken down his web site. Because his books are free-as-in-speech, his valuable contributions to the digital commons are still out there, making people's lives better.
We would all be a lot richer if more people could be convinced of what a good thing copyleft licenses are. When it comes to books, the problem seems to be that people underestimate how hard it is to do commercially successful writing. They have this illusion that they're going to make all kinds of money from their wonderful book, and they see copyleft licensing as being incompatible with that. The hard truth is that even a good, well-written book is seldom significantly profitable.
The right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures, shall not be violated, and no Warrants shall issue, but upon probable cause, supported by Oath or affirmation, and particularly describing the place to be searched, and the persons or things to be seized.
What about that is so complicated that the courts and the governor can't understand it? A cellphone is an effect and the Bill of rights says you need a warrant to search those. It offers no exceptions.
I think there are some parts that you're not understanding. There's the part about "unreasonable." If you get arrested, in any state of the union, the cops are almost certainly going to search you to see if you have a knife or a gun on you, and they're going to take away your wallet while you're in jail. This is not unconstitutional. If you want to argue that pawing around on someone's cell phone is constitutionally distinct from searching their pockets and removing their contents, then please feel free to do that. You just haven't done that yet.