So the point is to make the United States' efforts to stop terrorist attacks less effective?
I think it would be hard to make them less effective; they're pretty ineffective already.
How do you know that? I presume, since you're making this assertion, that you're cleared and have access to information most people do not on U.S. anti-terrorism operations? Or are you concluding that stuff you haven't heard about must therefore not exist?
Either way, the effectiveness (or lack thereof) of U.S. anti-terrorism operations had very little to do with the point I made in the post to which you replied.
This is precisely the outcome that Wikileaks was looking for: Assange's plan has been to leak information in order to make those who wish to keep secrets paranoid, so that they clamp down on their own internal communications and become less effective:
So the point is to make the United States' efforts to stop terrorist attacks less effective?
I know that's not what you're trying to say; it's not even what Assange is trying to say. But it's *one* of the effects of this process -- not the only one, I know, and people will argue that more good than harm has been done by these leaks. But it can't realistically be questioned that harm has been done. The question is essentially whether one believes that governments should ever keep secrets. The position of Assange, and most people here, appears to be "no, they shouldn't, ever." The kindest thing I can say about that position is that it's naive.
z=8.6 corresponds to an apparently recession velocity of 0.9785c.
The formula of interest is (1+z) = wavelength_obs / wavelength_emitted = [ (1+\beta) / (1-\beta) ]^0.5, where \beta = v/c, and v = apparent line of sight velocity. Invert that equation for beta and you get \beta = [ (1+z)^2 - 1 ] / [ (1+z)^2 + 1 ]. Plug in z=8.6 and there's your answer.
This is the one I came to this thread to post about. I *loved* multiplayer DECWAR on the DEC-10, and spent hundreds and hundreds of hours playing its child MegaWars on Compuserve with/against a bunch of other players. It was the only reason I ever accessed Compuserve. I'm sure if I played it now, it wouldn't have the same impact; but I miss the way I felt playing DECWAR/MegaWars. It was a blast.
Without actually going and reading the articles in question, if the proposals discussed weren't put forward or at least publicly defended by Bush, then I agree with you 100%. Issues like this are so incredibly far down the list of priorities for a president, I have no doubt that their knowledge of this topic is at the level of being told "we have people working on some proposals about this" by a staffer.
I love how the OP gave this article a title of "Obama Wants . .." (well, the submission used "US President wants. .."). Not the FBI or the DOJ or the NSA, or even "Feds Want . .." in order to be comprehensive; but Obama. As if this was some devious idea Obama had while dining on babies, rather than something the law enforcement and national security comunities have been working up for more than a half-decade. Of course he's responsible for the actions of the administration while he's president; but that's a long way from this being part of his nefarious plan for fascism. I looked for the quote from Obama or a spokesperson of his in TFA -- something, *anything* indicating this was an initiative specifically coming from him -- but couldn't find it. Nonetheless, just as the OP intended, 90% of the replies have been about Obama, rather than about the actual regulations. Way to be manipulated, folks. Given this, how unsurprising that the story link accompanying the submission was to Fox News, even though that Fox News story does absolutely nothing more than quote a story in the NYT.
And to head it off at the pass -- it shouldn't be necessary, but someone here will try it anyway -- I can't stand Obama. I think he's been terrible in a variety of ways. I just also can't stand people who are intellectually dishonest in an effort to score political points.
It is an insightful comment, but it lacks enough information for some people to share the insight.
(rest of your post snipped)
It's probable that nobody's reading this anymore; but just in case . ..
I agree with a lot of what you say, but the point I was trying to make with my reply was more fundamental.
The poster to whom I replied referred to a scientific theory being *proven*. This represents a fundamental misconception of science. Science is not in the business of proving things true. In fact, if it's in the business of proving anything at all, it's proving things *false*.
To elaborate: it is impossible to prove a scientific theory to be true. No matter how much evidence you have in favor of a theory, it's always possible that tomorrow, someone will conceive of and execute an experiment under circumstances that the theory implicitly says shouldn't matter that then provides a result that's inconsistent with the theory. You can accumulate evidence in favor of a theory, but you can never, ever prove a theory to be true. And people who say "________ is just a theory that hasn't been proved" thus are advertising that they don't know what they're talking about.
But while you can't prove anything true in science, you can prove things false. A theory that makes firm predictions that fail the test of experiment is wrong.
No, sir, I disagree with that. It isn't just about models that can predict things.
You would agree with me that archeology is a part of science, is it not?
No, I would say it is not; although archaeologists certainly use some tools of science in their work. Archaeology to me is a branch of anthropology, and is no more a science than history is. Paleontology, OTOH, can be science.
Evolution only explains how we got here, it makes no prediction about where we will be (and it can't).
That's not how scientists use the word "prediction." In science, a prediction simply means "if I go and do this experiment or conduct this observation, what would my theory tell me I should find?" Evolutionary theory has made predictions about what we would expect to see in the fossil record, the comparative anatomy of genetically similar species (or, similarly, the genetic sequences present in morphologically similar species), the geographical distribution of species, etc.
And I have no idea what the Big Bang predicts exactly. Maybe you can enlighten me.
The dynamic nature of space (i.e. that it's not static). (observed)
The existence of the cosmic microwave background, with a blackbody spectrum (observed) and an energy density that scales with redshift in a specific way (observed at multiple redshifts).
The existence of the cosmic neutrino background, with an energy density that relates to the energy density of the CMBR in a specific way. (this is a prediction that hasn't yet been observed, by the way; but experimentally we're a long way away from being able to try.)
The cosmic abundances of hydrogen, helium and lithium. (observed)
I'm not sure I understand the questions in your post; so rather than trying to answer them, I'll just post what they're actually doing at the LHC and hope that it answers your questions.
The LHC is a ring-shaped particle accelerator. It accelerates counter-rotating beams of subatomic particles (normally, protons) to extremely high energies, and arranges for the particles in the beams to "collide" in several collision halls located at various places around the ring. Fundamental particles can interact with each other in a number of ways which can result in (for example) the annihilation of the original particles and the creation of new ones. As the energy of the interaction/collision goes up, the manner of interactions available change -- that is, the nature of the fundamental forces between particles depends on the energy of their interaction. This is not speculation: we've already observed this sort of thing. At LEP (an earlier particle accelerator, also located at CERN like the LHC is), for instance, back in the 80s, we saw that at high enough energies, two fundamental forces (the electromagnetic force and the weak force) unify and become the electroweak interaction, as theorized years earlier. There are a number of reasons, mostly theoretical in nature, for why we expect similar changes to the fundamental interactions at even higher energies. So, we build accelerators that get particles moving to higher and higher speeds (energies) before allowing them to come together and interact, in order to see how they interact and whether there's evidence for the kind of new physics that people expect.
The Big Bang comes in when you consider that the expansion of the Universe reduces the energy of the particles within it. If you imagine running the film backwards, looking into the past of the Universe, you get to a state where it was so hot that the atoms in the Universe would be ionized -- we had a sea of simple nuclei and electrons, with photons interacting with them. Run the film a little forward again, and as the Universe expands and the stuff within it cools, the electrons and nuclei combine to form atoms while around the same time, the likelihood of any one photon interacting with matter drops to where most photons in the Universe are likely to fly freely through it. Those photons are what we see in the Cosmic Microwave Background -- you may have heard of that. Now, consider still earlier times in the Universe. As you run the film backward, you'll eventually get to a point where the typical energies of matter are comparable to the binding energies of nuclei. Earlier than this in the Universe's history, nucleons (protons and neutrons) could come together and form simple nuclei, while nuclei could also break up as the energies of the nucleons typically exceeded the nuclear binding energies. As the Universe expanded and cooled, it passed through this transition where the nuclei that had formed stuck around. People call this era "Big Bang Nucleosynthesis" and have done calculations of how much hydrogen, helium, lithium, etc., should have been produced that do a pretty good job of matching what astronomical observations tell us. Now consider even earlier times. As you look further back, you'll get to a time where the average energies in the Universe are comparable to the binding energies of the nucleons themselves. People use the expression "quark-gluon plasma" to refer to the state of the Universe immediately preceding the transition when nucleons form for good. This is the state of matter they're talking about in TFA. In principle, if we collide subatomic particles together at sufficiently high energies, we can recreate (in a very very very small volume of space) the conditions that existed in the Universe at that time; observing the results of the collision will hopefully tell us whether such a state can indeed exist, as we think, and what it might have been like.
But it's incorrect to think of this state as being the state of matter "immediately" after the Big Bang, because "immedia
As soon as you say "Until _(insert any scientific theory at all here)_ can be proven . ..," you've demonstrated that you don't understand even the tiniest little bit of how science is done or what scientific understanding is.
That's a rather 'tricky' statement don't you think? First, I'll agree with you in that gravity doesn't technically reach zero. But it does appear to have to propagate. In a system many thousand of lightyears across, propagation delay would be significant.
I'm not sure how this makes my statement about gravity not having a range "tricky"; but it's definitely something worth thinking about. Several thousand lightyears is actually a pretty small-scale simulation; the simulation volume wouldn't be large enough to contain a typical bright galaxy. Cosmological simulations incorporating galaxy formation typically use volumes tens or even hundreds of megaparsecs (Mpc) on a side. Imagine you're working with a 100 Mpc per-side cube (for the cognoscenti: taking h=1 because I don't feel like carrying notation around). You typically use periodic boundary conditions, so the furthest mass from you is 50 Mpc away. Light travels at about 300 Mpc/Gyr; so it'll take about 1/6 Gyr for changes in the distribution of sources of the gravitational field to impact the field halfway across the box. That's a long time. So you might imagine that this is a major issue.
However, in one of these simulations, when evaluating the gravitational potential at the location of a point mass of interest, it's the stuff out at the largest scales that's treated in the most simplistic fashion -- that's how they avoid having to calculate pair forces between all the point masses in the simulation, which would make the computational time scale as N^2. Generally, you do some simplistic calculation of the gravitational potential at the point mass of interest, using a simplification of the mass distribution at large scales, and then calculate pair forces between the point mass of interest and others very nearby as a correction to the simplistic calculation. This simplification introduces error; but the folks who work on this are generally careful to set it up so that the error introduced is small enough to be acceptable (how they do that and can feel pretty confident about it would have to be another post), given that simplifications like this permit you to do the simulation in the first place. So, to my point mass of interest, the distant stuff 50 Mpc away is represented at low resolution. Typical peculiar velocities of masses in intergalactic space are 500 km/s and under, often well under. 500km/s is about 0.5 Mpc/Gyr. So in that delay time of 1/6 Gyr we were talking about earlier, distant stuff will have typically moved under 100 kpc. Compared to how we simplify the mass distribution at large distances to make the problem computationally tractable, that's nothing. There are some simulations where you have to care about this; but in general, ignoring it doesn't introduce as much error as you might think.
Incidentally, this kind of simplification helps parallelization quite a bit. If volumes of the simulation are allocated to nodes of a cluster, two nodes considering portions of the simulation volume which are very distant from each other may care about little more than the total mass in the other node's volume and where the center of mass of that stuff is located.
Not only that, but wouldn't the galaxy have expanded several million, if not billions of miles in the 27,000 years it would take for light to travel from one end to the other? (I'm not trusting my back of the envelope calcuations which put it at expanding 500 billion miles over 27,000 years)
This is only a significant effect for separations that are not small compared to the size of the theoretical horizon. And at any rate, it's straightforward to consider. The simulations are done in comoving coordinates (that is, coordinates that expand with the expansion). Working in comoving coordinates introduces some powers of the scale factor (well, inverse factors typically) that you have to include in the equations you solve; but that's OK.
That's correct. In a simulation like this, the most important physical effect to model is gravity. Gravity doesn't have a range. For each timestep in the simulation, all the mass in the simulation has to interact with all the other mass in the simulation. There are a variety of numerical tricks that people who write these codes use to make the problem feasible, so that the computation time required doesn't scale as N^2, with N = number of particles in the simulation. But even with these tricks, to calculate the force on an individual particle, you still have to care about the stuff outside your local volume. These are problems you have to solve when you parallelize your code. Distributing the problem in an @home fashion would require so much inter-participant communication that at this point, it wouldn't really be practical.
deserves to get screwed.
Seriously, go publish the songs yourself as an independent band. You don't need to be a record label to get it on itunes either (I think)
It's not as easy as you think. Really.
Eight years ago, Janis Ian, a performer who's had a hit song or two and been recording and releasing albums for 45 years now, did a *fantastic* interview here on/., with questions submitted by the readership. It's worth reading -- one of the best things I've ever read on Slashdot. I bet you'll find that the opinions she expresses about how repugnant the RIAA and major labels can be aren't so far from yours. And yet, she takes pains to emphasize that the major labels have a lot to offer a budding artist (see Question #10 and her response).
You need to be careful here. When you talk about relativity "not extending down to small scales," you're referring to General Relativity. Special relativity, OTOH, is a fundamental component of Quantum Field Theory.
Crud. The very first thing I thought of when I saw this was "cool, a high-res DEM to create terrain for FlightGear." SRTM is getting long in the tooth.
Not all Zappa is weird. I don't even think of *most* Zappa as weird. However, most of it *is* pretty complex stuff. He occasionally wrote pieces for orchestra that had passages considered unplayable by human musicians. OTOH, that which isn't complex often tends to the opposite extreme: the ribald or scatalogical stuff is frequently very simple musically.
So what's the appeal? Each fan would give you a different answer, and the answer would probably vary from track to track. I'll just pick two songs from his enormous repertoire and explain what their appeal is to me:
"Watermelon in Easter Hay," from the pseudo-rock-opera Joe's Garage. This nine-minute instrumental is a vehicle for Zappa's guitar soloing. It appears on some other live albums of his, but I think this studio version is the best, because it projects the somewhat sad feel of the piece the best. Prior to when I first heard this song, I always thought of guitar soloing as a means for lead guitarists with big egos to show off their technique; to the extent that electric lead guitar solos expressed emotion, those emotions tended to be upbeat, energetic ones, like anger or joy. Not here: the soloing in "Watermelon in Easter Hay" is instead evocative of a late afternoon, staring out the window into the rain while thinking of something sad. It is gorgeous melancholy, from the melody he works and plays with and twists, to the tone of the guitar itself. I loved this song for years purely on that level; but something about its structure always seemed odd to me until I realized that it's played in a non-standard time signature. The song is in 9/4 time, which subconsciously to us produces some discomfort or edginess, which adds to the emotional effect.
"The Black Page (drum solo, part 1, and part 2)" from Zappa in New York. This song, in the three forms in which it appears on this album, is a fabulous opportunity for learning about music, or at least about Zappa's concept of music. The song was originally a drum/percussion solo; a second version, immediately following the first on this album, adds other instruments. When I first heard this, I knew less than nothing about music, and the percussion song just seemed like a bunch of pointless banging with no real rhyme or reason; and the version with additional instrumentation ("The Black Page Part One, the Hard Version") seemed kinda boring and pointless as well. Somewhat later in this live album, however, he revisits it again, this time with the full band and arranged to a upbeat vamp ("The Black Page Part Two, the Easy Teenage New York Version"). In this form, I found the song easy to follow, and reasonably entertaining. And then time passed, and I learned how to play the guitar, and listened to a lot of jazz and orechestral music in the interim. And then one day I was listening to this album, and I made the connection between the "Easy" version and the "Hard" version -- I realized what he was trying to do. And that made me go back and listen to it a few more times, and then go back some more and listen to the Black Page drum solo -- the song stripped down to nothing but percussion, and I could hear all kinds of things going on that I couldn't before. It's hard to explain, but there were levels of complexity there that weren't apparent to me at first, but came later. And I love a lot of his music for revealing its secrets over time like that.
One of the problems in picking up Zappa discs is the range of music amongst them: orchestral music, jazz, free jazz, blues, straight-up rock, experimental music, etc. You could listen to ten FZ albums and not like anything on any of them, and that still wouldn't mean there isn't FZ stuff out there you'd like. There's often some commonality between recordings in a certain period of time (the first three Mothers albums, or the 73-75 band recordings); but even that's not consistently the case (his 80s recordings jumped all over the stylistic map going from release t
And if it is something the Feds can do, let them prove it in the one school sytem Congress can take direct responsibility for.
After all, if the DC school system is truly excellent, then there should be no problem applying those policies and funding decisions to other school systems.
What, the DC school system is not among the finest in the nation?
(snip)
Maybe we should return control of local school systems back to local school boards. And let Congress and the DOE control only the DC school system. When the DC school system is ranked among the top 25 then perhaps we might want to pay attention to the example set by Washington. Pay attention to the example - not do as they say. Under local control, some schools would undoubtably do better, some might do worse, but DC is dead last right now - so even your religious nutjob nightmare districts are still likely to do a better job than the nations capital.
I'm stunned this was modded as "Insightful." As someone who actually lives in DC, I can tell you that the involvement of Congress in the DC Public Schools is zero. However Congress' powers of oversight may *allow* Congress to get involved, the practical fact of the matter is that they do not. Instead, the absolutely awful DC public school system is treated by Congress in exactly the same way as every other school district throughout the United States. It is not an example of a failure of Federal management, since there isn't any more here than there is for Schnectady, New York or Hays, Kansas.
Because of demands on my time, I eat carryout/delivery way more than I'd like, or should (for both health and money reasons). With regard to calorie-counting approaches like The Hacker's Diet, how do you figure stuff like this? Obviously there's a way to do it for fast-food, but I'm not talking about fast-food. I'm talking about a dinner portion of chicken tikka masala from the Punjabi place up the street, or garlic dill potatoes from the soul food restaurant. How do those of you who have successfully applied The Hacker's Diet deal with stuff where the calorie content isn't easily discoverable?
Hah. I came to/. today just to see if someone had posted the xkcd geocities tribute. Everything from the background, the revolving "@" symbol, the under construction GIFs, and especially the malformed HTML coming across as text content, is exceptionally well done.
Addendum to the size recommendation: when I was in HS, we read A Canticle for Leibowitz in an AP English class. That's about as big a book as I'd recommend.
You might as well have asked people to name their favorite fantasy or sci-fi authors; you're going to get zillions of lists of recommendations without much guidance on what to pick and why.
IMHO, you need to look at that course description and ask questions like "Can you suggest some high quality fantasy or sci-fi works that have as their core theme "the relationship of humans with their environment" or "the nature of intelligence" or whatever.
Two recommendations I'd make:
1. Don't be afraid to go old (H.G. Wells _The Time Machine_, for instance, attempts to make some provocative claims about what happens to an increasingly technological society -- remarkable given when it was written).
2. Steer away from huge works. LOTR is my favorite fantasy book; but books like that are too big. They prevent you from reading too much other stuff because of time constraints.
Slashdot Mirror
So the point is to make the United States' efforts to stop terrorist attacks less effective?
I think it would be hard to make them less effective; they're pretty ineffective already.
How do you know that? I presume, since you're making this assertion, that you're cleared and have access to information most people do not on U.S. anti-terrorism operations? Or are you concluding that stuff you haven't heard about must therefore not exist?
Either way, the effectiveness (or lack thereof) of U.S. anti-terrorism operations had very little to do with the point I made in the post to which you replied.
This is precisely the outcome that Wikileaks was looking for: Assange's plan has been to leak information in order to make those who wish to keep secrets paranoid, so that they clamp down on their own internal communications and become less effective:
So the point is to make the United States' efforts to stop terrorist attacks less effective?
I know that's not what you're trying to say; it's not even what Assange is trying to say. But it's *one* of the effects of this process -- not the only one, I know, and people will argue that more good than harm has been done by these leaks. But it can't realistically be questioned that harm has been done. The question is essentially whether one believes that governments should ever keep secrets. The position of Assange, and most people here, appears to be "no, they shouldn't, ever." The kindest thing I can say about that position is that it's naive.
Re-read what he wrote; what you wrote isn't equivalent.
The title of this submission should have read "Cooks Source". Cooks is a completely different magazine.
z=8.6 corresponds to an apparently recession velocity of 0.9785c.
The formula of interest is (1+z) = wavelength_obs / wavelength_emitted = [ (1+\beta) / (1-\beta) ]^0.5, where \beta = v/c, and v = apparent line of sight velocity. Invert that equation for beta and you get \beta = [ (1+z)^2 - 1 ] / [ (1+z)^2 + 1 ]. Plug in z=8.6 and there's your answer.
I played it a little bit; friends played it more. It was hard to keep a group together long enough to play a whole game.
This is the one I came to this thread to post about. I *loved* multiplayer DECWAR on the DEC-10, and spent hundreds and hundreds of hours playing its child MegaWars on Compuserve with/against a bunch of other players. It was the only reason I ever accessed Compuserve. I'm sure if I played it now, it wouldn't have the same impact; but I miss the way I felt playing DECWAR/MegaWars. It was a blast.
Without actually going and reading the articles in question, if the proposals discussed weren't put forward or at least publicly defended by Bush, then I agree with you 100%. Issues like this are so incredibly far down the list of priorities for a president, I have no doubt that their knowledge of this topic is at the level of being told "we have people working on some proposals about this" by a staffer.
I love how the OP gave this article a title of "Obama Wants . . ." (well, the submission used "US President wants. . ."). Not the FBI or the DOJ or the NSA, or even "Feds Want . . ." in order to be comprehensive; but Obama. As if this was some devious idea Obama had while dining on babies, rather than something the law enforcement and national security comunities have been working up for more than a half-decade. Of course he's responsible for the actions of the administration while he's president; but that's a long way from this being part of his nefarious plan for fascism. I looked for the quote from Obama or a spokesperson of his in TFA -- something, *anything* indicating this was an initiative specifically coming from him -- but couldn't find it. Nonetheless, just as the OP intended, 90% of the replies have been about Obama, rather than about the actual regulations. Way to be manipulated, folks. Given this, how unsurprising that the story link accompanying the submission was to Fox News, even though that Fox News story does absolutely nothing more than quote a story in the NYT.
And to head it off at the pass -- it shouldn't be necessary, but someone here will try it anyway -- I can't stand Obama. I think he's been terrible in a variety of ways. I just also can't stand people who are intellectually dishonest in an effort to score political points.
It is an insightful comment, but it lacks enough information for some people to share the insight.
(rest of your post snipped)
It's probable that nobody's reading this anymore; but just in case . . .
I agree with a lot of what you say, but the point I was trying to make with my reply was more fundamental.
The poster to whom I replied referred to a scientific theory being *proven*. This represents a fundamental misconception of science. Science is not in the business of proving things true. In fact, if it's in the business of proving anything at all, it's proving things *false*.
To elaborate: it is impossible to prove a scientific theory to be true. No matter how much evidence you have in favor of a theory, it's always possible that tomorrow, someone will conceive of and execute an experiment under circumstances that the theory implicitly says shouldn't matter that then provides a result that's inconsistent with the theory. You can accumulate evidence in favor of a theory, but you can never, ever prove a theory to be true. And people who say "________ is just a theory that hasn't been proved" thus are advertising that they don't know what they're talking about.
But while you can't prove anything true in science, you can prove things false. A theory that makes firm predictions that fail the test of experiment is wrong.
No, sir, I disagree with that. It isn't just about models that can predict things.
You would agree with me that archeology is a part of science, is it not?
No, I would say it is not; although archaeologists certainly use some tools of science in their work. Archaeology to me is a branch of anthropology, and is no more a science than history is. Paleontology, OTOH, can be science.
Evolution only explains how we got here, it makes no prediction about where we will be (and it can't).
That's not how scientists use the word "prediction." In science, a prediction simply means "if I go and do this experiment or conduct this observation, what would my theory tell me I should find?" Evolutionary theory has made predictions about what we would expect to see in the fossil record, the comparative anatomy of genetically similar species (or, similarly, the genetic sequences present in morphologically similar species), the geographical distribution of species, etc.
And I have no idea what the Big Bang predicts exactly. Maybe you can enlighten me.
The dynamic nature of space (i.e. that it's not static). (observed)
The existence of the cosmic microwave background, with a blackbody spectrum (observed) and an energy density that scales with redshift in a specific way (observed at multiple redshifts).
The existence of the cosmic neutrino background, with an energy density that relates to the energy density of the CMBR in a specific way. (this is a prediction that hasn't yet been observed, by the way; but experimentally we're a long way away from being able to try.)
The cosmic abundances of hydrogen, helium and lithium. (observed)
I'm not sure I understand the questions in your post; so rather than trying to answer them, I'll just post what they're actually doing at the LHC and hope that it answers your questions.
The LHC is a ring-shaped particle accelerator. It accelerates counter-rotating beams of subatomic particles (normally, protons) to extremely high energies, and arranges for the particles in the beams to "collide" in several collision halls located at various places around the ring. Fundamental particles can interact with each other in a number of ways which can result in (for example) the annihilation of the original particles and the creation of new ones. As the energy of the interaction/collision goes up, the manner of interactions available change -- that is, the nature of the fundamental forces between particles depends on the energy of their interaction. This is not speculation: we've already observed this sort of thing. At LEP (an earlier particle accelerator, also located at CERN like the LHC is), for instance, back in the 80s, we saw that at high enough energies, two fundamental forces (the electromagnetic force and the weak force) unify and become the electroweak interaction, as theorized years earlier. There are a number of reasons, mostly theoretical in nature, for why we expect similar changes to the fundamental interactions at even higher energies. So, we build accelerators that get particles moving to higher and higher speeds (energies) before allowing them to come together and interact, in order to see how they interact and whether there's evidence for the kind of new physics that people expect.
The Big Bang comes in when you consider that the expansion of the Universe reduces the energy of the particles within it. If you imagine running the film backwards, looking into the past of the Universe, you get to a state where it was so hot that the atoms in the Universe would be ionized -- we had a sea of simple nuclei and electrons, with photons interacting with them. Run the film a little forward again, and as the Universe expands and the stuff within it cools, the electrons and nuclei combine to form atoms while around the same time, the likelihood of any one photon interacting with matter drops to where most photons in the Universe are likely to fly freely through it. Those photons are what we see in the Cosmic Microwave Background -- you may have heard of that. Now, consider still earlier times in the Universe. As you run the film backward, you'll eventually get to a point where the typical energies of matter are comparable to the binding energies of nuclei. Earlier than this in the Universe's history, nucleons (protons and neutrons) could come together and form simple nuclei, while nuclei could also break up as the energies of the nucleons typically exceeded the nuclear binding energies. As the Universe expanded and cooled, it passed through this transition where the nuclei that had formed stuck around. People call this era "Big Bang Nucleosynthesis" and have done calculations of how much hydrogen, helium, lithium, etc., should have been produced that do a pretty good job of matching what astronomical observations tell us. Now consider even earlier times. As you look further back, you'll get to a time where the average energies in the Universe are comparable to the binding energies of the nucleons themselves. People use the expression "quark-gluon plasma" to refer to the state of the Universe immediately preceding the transition when nucleons form for good. This is the state of matter they're talking about in TFA. In principle, if we collide subatomic particles together at sufficiently high energies, we can recreate (in a very very very small volume of space) the conditions that existed in the Universe at that time; observing the results of the collision will hopefully tell us whether such a state can indeed exist, as we think, and what it might have been like.
But it's incorrect to think of this state as being the state of matter "immediately" after the Big Bang, because "immedia
As soon as you say "Until _(insert any scientific theory at all here)_ can be proven . . .," you've demonstrated that you don't understand even the tiniest little bit of how science is done or what scientific understanding is.
Gravity doesn't have a range.
That's a rather 'tricky' statement don't you think? First, I'll agree with you in that gravity doesn't technically reach zero. But it does appear to have to propagate. In a system many thousand of lightyears across, propagation delay would be significant.
I'm not sure how this makes my statement about gravity not having a range "tricky"; but it's definitely something worth thinking about. Several thousand lightyears is actually a pretty small-scale simulation; the simulation volume wouldn't be large enough to contain a typical bright galaxy. Cosmological simulations incorporating galaxy formation typically use volumes tens or even hundreds of megaparsecs (Mpc) on a side. Imagine you're working with a 100 Mpc per-side cube (for the cognoscenti: taking h=1 because I don't feel like carrying notation around). You typically use periodic boundary conditions, so the furthest mass from you is 50 Mpc away. Light travels at about 300 Mpc/Gyr; so it'll take about 1/6 Gyr for changes in the distribution of sources of the gravitational field to impact the field halfway across the box. That's a long time. So you might imagine that this is a major issue.
However, in one of these simulations, when evaluating the gravitational potential at the location of a point mass of interest, it's the stuff out at the largest scales that's treated in the most simplistic fashion -- that's how they avoid having to calculate pair forces between all the point masses in the simulation, which would make the computational time scale as N^2. Generally, you do some simplistic calculation of the gravitational potential at the point mass of interest, using a simplification of the mass distribution at large scales, and then calculate pair forces between the point mass of interest and others very nearby as a correction to the simplistic calculation. This simplification introduces error; but the folks who work on this are generally careful to set it up so that the error introduced is small enough to be acceptable (how they do that and can feel pretty confident about it would have to be another post), given that simplifications like this permit you to do the simulation in the first place. So, to my point mass of interest, the distant stuff 50 Mpc away is represented at low resolution. Typical peculiar velocities of masses in intergalactic space are 500 km/s and under, often well under. 500km/s is about 0.5 Mpc/Gyr. So in that delay time of 1/6 Gyr we were talking about earlier, distant stuff will have typically moved under 100 kpc. Compared to how we simplify the mass distribution at large distances to make the problem computationally tractable, that's nothing. There are some simulations where you have to care about this; but in general, ignoring it doesn't introduce as much error as you might think.
Incidentally, this kind of simplification helps parallelization quite a bit. If volumes of the simulation are allocated to nodes of a cluster, two nodes considering portions of the simulation volume which are very distant from each other may care about little more than the total mass in the other node's volume and where the center of mass of that stuff is located.
Not only that, but wouldn't the galaxy have expanded several million, if not billions of miles in the 27,000 years it would take for light to travel from one end to the other? (I'm not trusting my back of the envelope calcuations which put it at expanding 500 billion miles over 27,000 years)
This is only a significant effect for separations that are not small compared to the size of the theoretical horizon. And at any rate, it's straightforward to consider. The simulations are done in comoving coordinates (that is, coordinates that expand with the expansion). Working in comoving coordinates introduces some powers of the scale factor (well, inverse factors typically) that you have to include in the equations you solve; but that's OK.
That's correct. In a simulation like this, the most important physical effect to model is gravity. Gravity doesn't have a range. For each timestep in the simulation, all the mass in the simulation has to interact with all the other mass in the simulation. There are a variety of numerical tricks that people who write these codes use to make the problem feasible, so that the computation time required doesn't scale as N^2, with N = number of particles in the simulation. But even with these tricks, to calculate the force on an individual particle, you still have to care about the stuff outside your local volume. These are problems you have to solve when you parallelize your code. Distributing the problem in an @home fashion would require so much inter-participant communication that at this point, it wouldn't really be practical.
deserves to get screwed. Seriously, go publish the songs yourself as an independent band. You don't need to be a record label to get it on itunes either (I think)
It's not as easy as you think. Really.
Eight years ago, Janis Ian, a performer who's had a hit song or two and been recording and releasing albums for 45 years now, did a *fantastic* interview here on /., with questions submitted by the readership. It's worth reading -- one of the best things I've ever read on Slashdot. I bet you'll find that the opinions she expresses about how repugnant the RIAA and major labels can be aren't so far from yours. And yet, she takes pains to emphasize that the major labels have a lot to offer a budding artist (see Question #10 and her response).
You need to be careful here. When you talk about relativity "not extending down to small scales," you're referring to General Relativity. Special relativity, OTOH, is a fundamental component of Quantum Field Theory.
Crud. The very first thing I thought of when I saw this was "cool, a high-res DEM to create terrain for FlightGear." SRTM is getting long in the tooth.
Not all Zappa is weird. I don't even think of *most* Zappa as weird. However, most of it *is* pretty complex stuff. He occasionally wrote pieces for orchestra that had passages considered unplayable by human musicians. OTOH, that which isn't complex often tends to the opposite extreme: the ribald or scatalogical stuff is frequently very simple musically.
So what's the appeal? Each fan would give you a different answer, and the answer would probably vary from track to track. I'll just pick two songs from his enormous repertoire and explain what their appeal is to me:
"Watermelon in Easter Hay," from the pseudo-rock-opera Joe's Garage. This nine-minute instrumental is a vehicle for Zappa's guitar soloing. It appears on some other live albums of his, but I think this studio version is the best, because it projects the somewhat sad feel of the piece the best. Prior to when I first heard this song, I always thought of guitar soloing as a means for lead guitarists with big egos to show off their technique; to the extent that electric lead guitar solos expressed emotion, those emotions tended to be upbeat, energetic ones, like anger or joy. Not here: the soloing in "Watermelon in Easter Hay" is instead evocative of a late afternoon, staring out the window into the rain while thinking of something sad. It is gorgeous melancholy, from the melody he works and plays with and twists, to the tone of the guitar itself. I loved this song for years purely on that level; but something about its structure always seemed odd to me until I realized that it's played in a non-standard time signature. The song is in 9/4 time, which subconsciously to us produces some discomfort or edginess, which adds to the emotional effect.
"The Black Page (drum solo, part 1, and part 2)" from Zappa in New York. This song, in the three forms in which it appears on this album, is a fabulous opportunity for learning about music, or at least about Zappa's concept of music. The song was originally a drum/percussion solo; a second version, immediately following the first on this album, adds other instruments. When I first heard this, I knew less than nothing about music, and the percussion song just seemed like a bunch of pointless banging with no real rhyme or reason; and the version with additional instrumentation ("The Black Page Part One, the Hard Version") seemed kinda boring and pointless as well. Somewhat later in this live album, however, he revisits it again, this time with the full band and arranged to a upbeat vamp ("The Black Page Part Two, the Easy Teenage New York Version"). In this form, I found the song easy to follow, and reasonably entertaining. And then time passed, and I learned how to play the guitar, and listened to a lot of jazz and orechestral music in the interim. And then one day I was listening to this album, and I made the connection between the "Easy" version and the "Hard" version -- I realized what he was trying to do. And that made me go back and listen to it a few more times, and then go back some more and listen to the Black Page drum solo -- the song stripped down to nothing but percussion, and I could hear all kinds of things going on that I couldn't before. It's hard to explain, but there were levels of complexity there that weren't apparent to me at first, but came later. And I love a lot of his music for revealing its secrets over time like that.
One of the problems in picking up Zappa discs is the range of music amongst them: orchestral music, jazz, free jazz, blues, straight-up rock, experimental music, etc. You could listen to ten FZ albums and not like anything on any of them, and that still wouldn't mean there isn't FZ stuff out there you'd like. There's often some commonality between recordings in a certain period of time (the first three Mothers albums, or the 73-75 band recordings); but even that's not consistently the case (his 80s recordings jumped all over the stylistic map going from release t
Yeah, the article poster is a bit confused.
And if it is something the Feds can do, let them prove it in the one school sytem Congress can take direct responsibility for. After all, if the DC school system is truly excellent, then there should be no problem applying those policies and funding decisions to other school systems.
What, the DC school system is not among the finest in the nation?
(snip)
Maybe we should return control of local school systems back to local school boards. And let Congress and the DOE control only the DC school system. When the DC school system is ranked among the top 25 then perhaps we might want to pay attention to the example set by Washington. Pay attention to the example - not do as they say. Under local control, some schools would undoubtably do better, some might do worse, but DC is dead last right now - so even your religious nutjob nightmare districts are still likely to do a better job than the nations capital.
I'm stunned this was modded as "Insightful." As someone who actually lives in DC, I can tell you that the involvement of Congress in the DC Public Schools is zero. However Congress' powers of oversight may *allow* Congress to get involved, the practical fact of the matter is that they do not. Instead, the absolutely awful DC public school system is treated by Congress in exactly the same way as every other school district throughout the United States. It is not an example of a failure of Federal management, since there isn't any more here than there is for Schnectady, New York or Hays, Kansas.
Because of demands on my time, I eat carryout/delivery way more than I'd like, or should (for both health and money reasons). With regard to calorie-counting approaches like The Hacker's Diet, how do you figure stuff like this? Obviously there's a way to do it for fast-food, but I'm not talking about fast-food. I'm talking about a dinner portion of chicken tikka masala from the Punjabi place up the street, or garlic dill potatoes from the soul food restaurant. How do those of you who have successfully applied The Hacker's Diet deal with stuff where the calorie content isn't easily discoverable?
Hah. I came to /. today just to see if someone had posted the xkcd geocities tribute. Everything from the background, the revolving "@" symbol, the under construction GIFs, and especially the malformed HTML coming across as text content, is exceptionally well done.
Addendum to the size recommendation: when I was in HS, we read A Canticle for Leibowitz in an AP English class. That's about as big a book as I'd recommend.
You might as well have asked people to name their favorite fantasy or sci-fi authors; you're going to get zillions of lists of recommendations without much guidance on what to pick and why.
IMHO, you need to look at that course description and ask questions like "Can you suggest some high quality fantasy or sci-fi works that have as their core theme "the relationship of humans with their environment" or "the nature of intelligence" or whatever.
Two recommendations I'd make:
1. Don't be afraid to go old (H.G. Wells _The Time Machine_, for instance, attempts to make some provocative claims about what happens to an increasingly technological society -- remarkable given when it was written).
2. Steer away from huge works. LOTR is my favorite fantasy book; but books like that are too big. They prevent you from reading too much other stuff because of time constraints.