If Hubble can se 95% of the "known" time, How did we get so far away anything in first 5% of time that the light had to use the remaining 95% of time to catch up?
The short answer is: the expansion of the Universe. You're probably thinking these two things:
that if the Universe has an age of t_o, the farthest away from us anything we can theoretically see can be (ignoring practical limitations such as the surface of last scattering or the redshifting of photon energies down below visible limits for the moment) is c*t_o, the speed of light times the age of the Universe;
that if we're viewing something from a time when the Universe is 5% of its current age, it must therefore be 95% of that distance c*t_o away.
Neither of these things are true in a Universe in which the background space is expanding.
1. open source projects don't really have deadlines, so they cannot fail. There is no manager to say "stop working on this" so there always exists the possibility that someone will take up the torch and finish the project or add the finishing touches that make it interesting to users.
Sure. But I think it's safe to say that often, no one will. This could be because there are now other projects that solve the problem better, serve the users better, pose more interesting challenges to developers, etc. Or it could be because technology has moved on and a project isn't really useful or needed anymore (dot matrix prettyprinting packages?). Or it could be because of a fork or spinoff occurring for whatever reason, and the original project dying from developer disinterest as its spinoff moves on. Or it could be something else entirely.
Let me put what I'm getting at another way. Suppose you're the manager/lead developer/HMFWIC of an open source project that's moderately successful: you have code, it runs, you have some interested contributors and a small but growing userbase. At this point, you might be interested in answers to the questions "what ought I to do right now to help my project continue to grow, and at least prevent it from withering?" Treatises like ESR's etc. make some specific suggestions (e.g. "release often," "encourage and facilitate bug reporting," "be willing to delegate some responsibility over chunks of the project," etc.). But I can imagine that a systematic look at the history of projects that finally withered might provide more insight into what the most important things to do/not do are than anecdotal evidence does.
Again, my comment (to which you replied) explicitly stated, in so many words that of course some projects fail for the reasons you outline, but that it's the failed projects that get beyond the stage(s) you outline that are the interesting ones for the purpose of this question.
It would be interesting to see such an analysis done with an open source-centric viewpoint: why open source/free software projects fail.
It would be necessary to structure the survey carefully to avoid the obvious results that don't contain useful information. For instance, Sourceforge is littered with old projects that never got past alpha or pre-alpha because no one was interested except for the project initiator (who never created enough of a start to encourage significant involvement from others), and the project initiator eventually lost interest him/herself. That may be the way in which most open source projects fail -- but that knowledge is of little use to someone running a project and looking for tips on management. There are of course books about aspects of this topic; but it would be nice if someone were to do a similar survey of open source projects that did get their legs underneath them, that did produce something that enticed involvement and an interested user community, only to eventually fail.
I was able to get in, logged in automatically, by going directly to the story page (from an RSS/RDF aggregator). But the homepage is no go, as you've all noted.
For the chinese web search, they remove listings that are unreachable from China. China's internet is filtered, regardless of anything Google does. Google simply saved the chinese users' time by hiding the links to content that they can't access anyway.
I think that's a fairly shallow way of looking at it. There is important information conveyed when one learns that there are sites (search results) that one is not allowed to reach. Put another way, there's a difference in the ideas you get in your head when you're not allowed to see contrary information versus when you're not even aware the contrary information exists.
Honestly? I think we're conditioned by the way in which 99.9% of Hollywood movies (especially action-adventure movies) end: climax, brief 2-3 minute denoument, roll credits. As you note, that's not at all the way the book is, in no small part because the book aimed at something different from a simple action-adventure. Peter Jackson didn't do a by-rote reproduction of the book, of course; but he did drift a little away from the standard action-adventure, or aspire to do more than what a-a's do. But the movie came across as one, so many people expected it to end the way action-adventure movies typically end.
The current state of the scope is that there is NO money for new telescopes other then the Webb telescope, but it's a radio scope and not an optical one (even though it's being sold as a Hubble replacement).
This was modded insightful? The Webb/NGST will be a near-IR telescope, not a radio telescope. As such, it is a partial replacement for the Hubble, as there is significant overlap in the wavelengths for which each were/will be used. If you consider perhaps the main purpose of the Webb/NGST to be high-z observations, then it's even more clearly a replacement for the Hubble.
Larry Krauss addressed this eight years ago in an excellent editorial for the NYTimes entitled "In Defense of Nonsense," which I reproduce below:
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July 29, 1996
In Defense of Nonsense
By Lawrence Krauss
CLEVELAND, Ohio -- Four months ago, when his Presidential campaign still seemed viable, Patrick Buchanan appeared on a national television program and argued in favor of creationism. This, by itself, is not so remarkable, given some of Mr. Buchanan's other views.
What seemed more significant, however, was that the same national media that questioned other Buchanan campaign planks like trade protectionism
and limits on immigration did not produce a major article or editorial proclaiming the candidate's views on evolution to be simple nonsense.
Why is this the case? Could it be that the fallacies inherent in a strict creationist viewpoint are so self-evident that they were deemed not to deserve comment? I think not. Indeed, when a serious candidate for the highest office of the most powerful nation on earth holds such views you would think that this commentary would automatically become "newsworthy."
Rather, what seems to have taken hold is a growing hesitancy among both journalists and scholars to state openly that some viewpoints are not subject to debate: they are simply wrong. They might point out flaws, but journalists also feel great pressure to report on both sides of a
"debate."
Part of the reason is that few journalists naturally feel comfortable enough on scientific matters to make pronouncements. But there is another good reason for such hesitancy. In a truly democratic society, one might argue, everything is open to debate.
Who has the authority to deem certain ideas incorrect or flawed? Indeed, appeal to authority is as much an anathema to scientists as it is to many on the academic left who worry about the authority of the "scientific establishment."
What is so wonderful about scientific truth, however, is that the authority which determines whether there can be debate or not does not reside in some fraternity of scientists; nor is it divine.
The authority rests with experiment.
It is perhaps the most immutable but most widely misunderstood property of modern science: a proposition can never be proved to be absolutely true. There can always be some experiment lurking around the corner to require alteration of any model of reality.
What is unequivocal, however, is falseness. A theory whose predictions fail the test of experiment is always wrong, period, end of story.
The earth isn't flat, because you can travel around it, period, end of story.
This misunderstanding is at the heart of much scholarly debate in recent months, including the amusing hoax that a New York University physicist, Alan Sokal, played at the expense of the editors of the journal Social Text. The postmodernist journal published a bogus article that Professor Sokal had written as a satire of some social science criticism of the nature of scientific knowledge.
It was aimed at those in the humanities who study the social context of science, but whom he argued could not discern empirically falsifiable models from meaningless nonsense.
The editors, on the other hand, argued that publication was based in part on their notion that the community of scholars depends on the goodwill of the participants -- namely they had assumed Professor Sokal had something to say.
They too have a point.
The great paranormal debunker and magician, the Amazing Randi, has shown time and again that earnest researchers can be duped by those who would have been willing to answer "yes" to the question "are you lying?" but who were never asked.
We must always be skeptical. Being skeptical, however does not get in the way of the search for objective truths.
It merely assists in the uncovering of falsehoods.
Another popular misunderstanding of the nature of truth and falsehood in modern scie
I'm calling bullshit. There are no sexually-explicit sites that target children. The credit card chargebacks on something like that would be overwhelming.
There certainly have sorta been sites that fall into that domain, even if it wasn't the site master's intent. Viz. this story from the winter.
I can understand (and agree with) this argument if all one does is use the pre-prepared campaigns and adventures put out by WotC. But if you're designing your own campaign, I don't see how this need be true. I can't tell you you're wrong, since I haven't run a game or played under D&D3 rules (since I'm not playing or running games at all these days). But you don't have to use the campaigns that WotC puts out.
Put another way, what is it about D&D3 (as opposed to AD&D2 or AD&D1 or original D&D -- don't know much about D&D2 myself) that prevents a creative referee from desigining an interesting campaign, containing involving stories, and presenting them in an engaging fashion?
Wait...I thought mankind was destroying the ozone layer, but man-made chemicals play an important role in ozone creation?
This is the stuff they were supposed to teach you in high school.
Both of the statements you say above are true. Yes, processes associated with human activity (basically, the production and release of chloroflurocarbons) have, over time, resulted in a degradation of the stratospheric ozone layer
(there is, fortunately, some evidence that things are finally improving here, but that's another conversation). And yes, pollutants associated with human activity produce tropospheric ozone.
These two statements do not in any way conflict. The key is the presence of the words "stratospheric" and "tropospheric."
Ozone is toxic to humans; you don't wanna breathe it. So you don't want it in the troposphere (low altitudes, where we are). If it's up in the stratosphere (very high altitudes), it's not around us, so we're not breathing it. Ozone in the stratosphere also does a good job of screening out sunlight of potentially harmful energies; ozone in the troposphere isn't effective at screening out UV radiation.
Unfortunately, tropospheric ozone doesn't really get much of a chance to rise up and replenish the stratospheric ozone, because ozone is such a fragile molecule. So you can't look on it as a good thing for that reason, either.
It's like rants about what "could have" happened if the quarterback had thrown for 2 more touchdowns, or if Lee had flanked instead of going up the middle at Chancellorsville,
I own over 3000 CDs; and while I like a lot of modern music, my music tastes aren't heavily influenced by what's hip this month (I'm usually about 5-7 years behind the times). And I like having physical CDs/LPs/whatever. So I just don't have much interest in p2p mp3 downloading, sorry.
No. This has been understood for decades.
on
When Galaxies Collide
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· Score: 5, Interesting
It the universe is expanding due to the Big Bang, then why would galaxy clusters ever meet?
The short answer is: because the Universe on these scales is not perfectly homogeneous. If it were, they wouldn't merge.
The longer answer:
Remember that the expansion of the Universe is an expansion of background space -- an expansion of the space in which everything is embedded -- rather than stuff moving through space. The rate of change of the relative separation of two hunks of matter can then be thought of as having two components: one from the expansion of space (objects staying in the same location, but the distances between objects are increasing because space is expanding), and one from the movement of objects through space (objects changing their locations in space). In the case of the latter -- the so-called "peculiar velocity" of an object -- if matter were distributed perfectly smoothly throughout the Universe, there'd be no reason for anything to change locations in space. But it isn't; and so there are net gravitational forces on objects that cause them to move. Whether the attraction of two objects "wins" over the expansion tending to separate them depends upon the situation.
For a simple way to picture this sort of thing, consider a big rubber sheet with two marbles on it. Give one a nudge towards the other (its peculiar velocity), and then start stretching the sheet (the expansion of the Universe). Will they collide? Depends on the peculiar velocity, rate of stretching (expansion), etc. But it's certainly not the case that they always won't.
Now, so far as I know, intersteller distances are measured by the light year; Alpha Centuri is ~4 light years away, etc.
Well, actually, parsecs (and kiloparsecs and megaparsecs) are what tend to be used, for mainly traditional reasons. But it's a straightforward unit conversion.
The problem is this: You can point the hubble in any direction, and get an equally old image. Further, if you take a deep enough image, you can (theoretically) take an image of the Big Bang itself (or X million years after it, whatever).
In practical fact, you can't see back to the Big Bang, for a number of reasons. The first is that until a few hundred thousand years after the putative Big Bang, the Universe was opaque to radiation. Photons were simply too unlikely to pass much of any distance through the Universe without scattering off a charged particle of some sort. After that point, the Universe became transparent to photons. Consequently, that's as far back as you can see -- with photons, anyway. But you're right that you can see this change of state in the Universe (the so-called "surface of last scattering") in any direction you look, and in fact that's what astrophysicists are looking at when they map the cosmic microwave background radiation.
The other thing that prevents you from seeing all the way back to the Big Bang is that as the Universe expands, light is redshifted (basically, its wavelengths are stretched out with the expansion). That's why we have to look in the infrared band for these distant galaxies, and that's why the light we observe from the surface of last scattering is in the microwave band.
Light emitted at times closer and closer to the putative Big Bang is redshifted by larger and larger degrees, approaching infinite redshifting at the Big Bang itself (when the scale factor of the Universe, describing the expansion of space relative to today, is 0). So even if the surface of last scattering wasn't there, there'd be a practical limit to just how far back one could see, based on just how low-energy (long-wavelength) of photons one could detect and interpret.
The paradox to me, is that this means the Big Bang can be conceptualized as a the outer edge of a sphere that surrounds us. You can, with the telescope, image in any direction in all three dimensions, and your limit wrt distance in any of those directions is the big bang. So the big bang is the edge.
The Big Bang occurred everywhere. It occurred where you're sitting, where I'm sitting, and where Zaphod is sitting.
Imagine some event -- say, the change of state that I described above, referred to as "decoupling", when the Universe became effectively transparent to photons, where before that it was opaque. This happened basically everywhere at once -- as the Universe expanded, densities and temperatures dropped until the scattering probabilities fell low enough. This happened everywhere, including right where you and I are now. But the photons that were around here then are long-gone now. They've been flying off in different directions since then. Similarly, the photons that were 10 light years away aren't around us either: the time they've had to fly, times the speed of light, is a long way from here.
If you think about it, the photons you're going to see are ones that started out on a shell that's centered on us, with a radius equal to the distance light could travel in the time since decoupling (it's a little more complicated than that because of the expansion, but that's the basic idea). At any later time, from 1 second to 1 billion years later, that shell will be larger.
So that's why we see a given time in the history of the Universe as a shell around us. It's not because these things (like the surface of last scattering, or the Big Bang itself) really are shells, but simply because that's all we can see. The photons that started at points interior to that shell aren't anywhere near us now; they've had enough time to propagate further than the distance between us and their starting points. The photons that started at points outside that shell haven't had enough time to reach us yet.
I don't think it's anything deep -- just that "often" is not the same as "usually". If polls are wrong a sixth of the time, it's not crazy to call that "often". (I haven't read the article, so I don't know whether it says that or not -- I just took 100% minus your quoted figure of 84% correct. But it's irrelevant to this comment)
Re:Stephen Hawking
on
Odds-on Science
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· Score: 4, Insightful
And yes, I'm a physicist.
So am I. Your characterization of Feynman vis-a-vis Hawking is silly, I think.
As you suggest, Hawking is indeed considered to be quite smart, but to have made contributions that haven't been that major to physics as a whole. Such concepts as the Hartle-Hawking equation, black hole evaporation, etc., have been quite interesting to people working in comparatively narrowly-defined areas; that plus their removal from unambiguous observational testing makes them at most curiosities to most of the physics community.
That's a pretty far cry from the contributions of Feynman. His work on QED, weak interactions, superfluidity, and the makeup of hadrons are each individually closely tied to experiment, and all of that work related to issues that nearly all theoretical physicists spend at least some time in their careers considering. Hell, pulling Feynman rules out of interaction Lagrangians, and using the diagrams that follow for solving perturbation expansion problems, are now staples not only of particle physics, but of solid state theory as well. He was tremendously influential. Nothing Hawking has done compares in its influence.
Regular people will never be affected by anything Hubble has ever done or will do, in the course of their lives. Hubble will not cure cancer or provide anyone with a faster car.
To be honest, it seems sad to me that these are the only sorts of ways in which you can imagine regular people being affected.
Tell us, what's so "awesome" about the data Hubble's provided so far, since it went live in 1990? How has it impacted your life since then (aside from giving you neat wallpapers)? How will it impact the lives of your grandchildren (aside from giving them neat wallpapers)? How has Hubble benefited you aside from the "wow that's neat" effect?
Well, I'm not the person to whom you were responding, but I'll answer this for myself: without the FOS on the HST, we would not have had two independent teams confirming each others results in the course of determining the eventual fate of the universe. Yes, that's affected me greatly. You may chalk that sort of effect as nothing more than a version of "wow, that's neat." But if so, I can only wonder whether you've ever experienced love in your life, since loving someone and having them love you doesn't result in cancer cures or faster cars either -- but it has a huge effect on us nonetheless. Various astronomical results, including some from the Hubble, have affected me in ways a hell of a lot more profound than the most recent sexy-but-ultimately-meaningless gadget or computer game.
Note that I'm not arguing in favor of keeping the Hubble going; I'm not addressing that at all. I'm merely responding to what seems to me to be a rather sad perspective on what it means to have an effect on lives. Have you ever heard a talented orator give the St. Crispin's day speech from Henry V? Did you really not feel an excited chill when you learned that the atoms that make us all up were at one time contained in a star that supernovaed? That latter one will humble me with awe decades after I've forgotten there ever was an iPod. What kind of effect does this stuff have on us? Nothing, and everything.
for example, feynman no doubt did some great physics, but he gets much, MUCH greater recognition over two other guys who did the same work (tomonaga and schwinger, they shared the nobel prize)
You're correct that Feynman was a more dynamic speaker/teacher, etc. But I think it's a bit of a jump to say that that's the only reason why he gets more attention than Schwinger and Tomonaga. For starters, they didn't all do the same work, even on QED. It's true that all three arrived at equivalent formalisms for calculating amplitudes, but that's not the same as saying they did the same work. Have you thrown away Feynman diagrams and straightforward perturbation expansions and instead tried to do things the way Schwinger did? It's a bitch! As a famous quote of the time went, "Feynman shows you how to do it; Schwinger shows you that only he can do it." And that had a lot to do with the eventual predominance of Feynman's perspective, and thus his getting more recognition than Schwinger or Tomonaga.
Furthermore, while I can't speak to Tomonaga in this regard, Feynman made a major splash in a much broader spectrum of physical investigations than Schwinger did. The work on QED was simply one of many arguably Nobel-worthy accomplishments of his. That, too, contributes to his being paid more attention to than Schwinger and Tomonaga.
Of course, you could argue that these are only things that matter to the cognoscenti; they don't explain why Feynman is more recognized by the general public. But I would claim that contrary to what physicists, and geeks who like physics, think, the general public is pretty oblivious to physicists entirely. They've heard of Einstein; they might have heard of Hawking. That's pretty much it, though. We think of Feynman as famous; the average person on the street has never heard of him.
So while I would agree that Feynman's dynamic personality, excellence in presentation, etc., is important in the way he is remembered by those who are aware of him at all, at least equally important is the fact that he did a ton of amazing new physics.
OT: "Better to die on your feet...
on
Black Hat
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· Score: 1
...Than to live on your knees. I don't know who said it,
The same person who said just about everything else of importance: James Brown.
Slashdot Mirror
The short answer is: the expansion of the Universe. You're probably thinking these two things:
Neither of these things are true in a Universe in which the background space is expanding.
1. open source projects don't really have deadlines, so they cannot fail. There is no manager to say "stop working on this" so there always exists the possibility that someone will take up the torch and finish the project or add the finishing touches that make it interesting to users.
Sure. But I think it's safe to say that often, no one will. This could be because there are now other projects that solve the problem better, serve the users better, pose more interesting challenges to developers, etc. Or it could be because technology has moved on and a project isn't really useful or needed anymore (dot matrix prettyprinting packages?). Or it could be because of a fork or spinoff occurring for whatever reason, and the original project dying from developer disinterest as its spinoff moves on. Or it could be something else entirely.
Let me put what I'm getting at another way. Suppose you're the manager/lead developer/HMFWIC of an open source project that's moderately successful: you have code, it runs, you have some interested contributors and a small but growing userbase. At this point, you might be interested in answers to the questions "what ought I to do right now to help my project continue to grow, and at least prevent it from withering?" Treatises like ESR's etc. make some specific suggestions (e.g. "release often," "encourage and facilitate bug reporting," "be willing to delegate some responsibility over chunks of the project," etc.). But I can imagine that a systematic look at the history of projects that finally withered might provide more insight into what the most important things to do/not do are than anecdotal evidence does.
Sigh.
Again, my comment (to which you replied) explicitly stated, in so many words that of course some projects fail for the reasons you outline, but that it's the failed projects that get beyond the stage(s) you outline that are the interesting ones for the purpose of this question.
Your response was a non-sequitur. What "expectation" did I suggest, and what does your response have to do with the question I posed?
It would be interesting to see such an analysis done with an open source-centric viewpoint: why open source/free software projects fail.
It would be necessary to structure the survey carefully to avoid the obvious results that don't contain useful information. For instance, Sourceforge is littered with old projects that never got past alpha or pre-alpha because no one was interested except for the project initiator (who never created enough of a start to encourage significant involvement from others), and the project initiator eventually lost interest him/herself. That may be the way in which most open source projects fail -- but that knowledge is of little use to someone running a project and looking for tips on management. There are of course books about aspects of this topic; but it would be nice if someone were to do a similar survey of open source projects that did get their legs underneath them, that did produce something that enticed involvement and an interested user community, only to eventually fail.
I was able to get in, logged in automatically, by going directly to the story page (from an RSS/RDF aggregator). But the homepage is no go, as you've all noted.
For the chinese web search, they remove listings that are unreachable from China. China's internet is filtered, regardless of anything Google does. Google simply saved the chinese users' time by hiding the links to content that they can't access anyway.
I think that's a fairly shallow way of looking at it. There is important information conveyed when one learns that there are sites (search results) that one is not allowed to reach. Put another way, there's a difference in the ideas you get in your head when you're not allowed to see contrary information versus when you're not even aware the contrary information exists.
Honestly? I think we're conditioned by the way in which 99.9% of Hollywood movies (especially action-adventure movies) end: climax, brief 2-3 minute denoument, roll credits. As you note, that's not at all the way the book is, in no small part because the book aimed at something different from a simple action-adventure. Peter Jackson didn't do a by-rote reproduction of the book, of course; but he did drift a little away from the standard action-adventure, or aspire to do more than what a-a's do. But the movie came across as one, so many people expected it to end the way action-adventure movies typically end.
The current state of the scope is that there is NO money for new telescopes other then the Webb telescope, but it's a radio scope and not an optical one (even though it's being sold as a Hubble replacement).
This was modded insightful? The Webb/NGST will be a near-IR telescope, not a radio telescope. As such, it is a partial replacement for the Hubble, as there is significant overlap in the wavelengths for which each were/will be used. If you consider perhaps the main purpose of the Webb/NGST to be high-z observations, then it's even more clearly a replacement for the Hubble.
Larry Krauss addressed this eight years ago in an excellent editorial for the NYTimes entitled "In Defense of Nonsense," which I reproduce below:
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July 29, 1996
In Defense of Nonsense
By Lawrence Krauss
CLEVELAND, Ohio -- Four months ago, when his Presidential campaign still seemed viable, Patrick Buchanan appeared on a national television program and argued in favor of creationism. This, by itself, is not so remarkable, given some of Mr. Buchanan's other views.
What seemed more significant, however, was that the same national media that questioned other Buchanan campaign planks like trade protectionism and limits on immigration did not produce a major article or editorial proclaiming the candidate's views on evolution to be simple nonsense.
Why is this the case? Could it be that the fallacies inherent in a strict creationist viewpoint are so self-evident that they were deemed not to deserve comment? I think not. Indeed, when a serious candidate for the highest office of the most powerful nation on earth holds such views you would think that this commentary would automatically become "newsworthy."
Rather, what seems to have taken hold is a growing hesitancy among both journalists and scholars to state openly that some viewpoints are not subject to debate: they are simply wrong. They might point out flaws, but journalists also feel great pressure to report on both sides of a "debate."
Part of the reason is that few journalists naturally feel comfortable enough on scientific matters to make pronouncements. But there is another good reason for such hesitancy. In a truly democratic society, one might argue, everything is open to debate.
Who has the authority to deem certain ideas incorrect or flawed? Indeed, appeal to authority is as much an anathema to scientists as it is to many on the academic left who worry about the authority of the "scientific establishment."
What is so wonderful about scientific truth, however, is that the authority which determines whether there can be debate or not does not reside in some fraternity of scientists; nor is it divine.
The authority rests with experiment.
It is perhaps the most immutable but most widely misunderstood property of modern science: a proposition can never be proved to be absolutely true. There can always be some experiment lurking around the corner to require alteration of any model of reality.
What is unequivocal, however, is falseness. A theory whose predictions fail the test of experiment is always wrong, period, end of story.
The earth isn't flat, because you can travel around it, period, end of story.
This misunderstanding is at the heart of much scholarly debate in recent months, including the amusing hoax that a New York University physicist, Alan Sokal, played at the expense of the editors of the journal Social Text. The postmodernist journal published a bogus article that Professor Sokal had written as a satire of some social science criticism of the nature of scientific knowledge.
It was aimed at those in the humanities who study the social context of science, but whom he argued could not discern empirically falsifiable models from meaningless nonsense.
The editors, on the other hand, argued that publication was based in part on their notion that the community of scholars depends on the goodwill of the participants -- namely they had assumed Professor Sokal had something to say.
They too have a point.
The great paranormal debunker and magician, the Amazing Randi, has shown time and again that earnest researchers can be duped by those who would have been willing to answer "yes" to the question "are you lying?" but who were never asked.
We must always be skeptical. Being skeptical, however does not get in the way of the search for objective truths.
It merely assists in the uncovering of falsehoods.
Another popular misunderstanding of the nature of truth and falsehood in modern scie
I'm calling bullshit. There are no sexually-explicit sites that target children. The credit card chargebacks on something like that would be overwhelming.
There certainly have sorta been sites that fall into that domain, even if it wasn't the site master's intent. Viz. this story from the winter.
Oh for heaven's sakes, this would have taken you maybe five seconds to check online.
The NRAO's headquarters are in Charlottesville, Virginia, and have been for a very long time.
The NRAO has facilities in a variety of locations, of which Green Bank is one.
How do you plan on doing high-quality UV and IR observations from ground-based telescopes?
I can understand (and agree with) this argument if all one does is use the pre-prepared campaigns and adventures put out by WotC. But if you're designing your own campaign, I don't see how this need be true. I can't tell you you're wrong, since I haven't run a game or played under D&D3 rules (since I'm not playing or running games at all these days). But you don't have to use the campaigns that WotC puts out.
Put another way, what is it about D&D3 (as opposed to AD&D2 or AD&D1 or original D&D -- don't know much about D&D2 myself) that prevents a creative referee from desigining an interesting campaign, containing involving stories, and presenting them in an engaging fashion?
Wait...I thought mankind was destroying the ozone layer, but man-made chemicals play an important role in ozone creation?
This is the stuff they were supposed to teach you in high school.
Both of the statements you say above are true. Yes, processes associated with human activity (basically, the production and release of chloroflurocarbons) have, over time, resulted in a degradation of the stratospheric ozone layer (there is, fortunately, some evidence that things are finally improving here, but that's another conversation). And yes, pollutants associated with human activity produce tropospheric ozone.
These two statements do not in any way conflict. The key is the presence of the words "stratospheric" and "tropospheric."
Ozone is toxic to humans; you don't wanna breathe it. So you don't want it in the troposphere (low altitudes, where we are). If it's up in the stratosphere (very high altitudes), it's not around us, so we're not breathing it. Ozone in the stratosphere also does a good job of screening out sunlight of potentially harmful energies; ozone in the troposphere isn't effective at screening out UV radiation.
So to summarize:
Stratospheric ozone: good.
Tropospheric ozone: bad.
Unfortunately, tropospheric ozone doesn't really get much of a chance to rise up and replenish the stratospheric ozone, because ozone is such a fragile molecule. So you can't look on it as a good thing for that reason, either.
In what way is GNOME 2.6 in Sarge not working for you? I'm running Sarge, and it's working for me.
It's like rants about what "could have" happened if the quarterback had thrown for 2 more touchdowns, or if Lee had flanked instead of going up the middle at Chancellorsville,
Uh, he did flank at Chancellorsville. Rather successfully, too.
I own over 3000 CDs; and while I like a lot of modern music, my music tastes aren't heavily influenced by what's hip this month (I'm usually about 5-7 years behind the times). And I like having physical CDs/LPs/whatever. So I just don't have much interest in p2p mp3 downloading, sorry.
It the universe is expanding due to the Big Bang, then why would galaxy clusters ever meet?
The short answer is: because the Universe on these scales is not perfectly homogeneous. If it were, they wouldn't merge.
The longer answer:
Remember that the expansion of the Universe is an expansion of background space -- an expansion of the space in which everything is embedded -- rather than stuff moving through space. The rate of change of the relative separation of two hunks of matter can then be thought of as having two components: one from the expansion of space (objects staying in the same location, but the distances between objects are increasing because space is expanding), and one from the movement of objects through space (objects changing their locations in space). In the case of the latter -- the so-called "peculiar velocity" of an object -- if matter were distributed perfectly smoothly throughout the Universe, there'd be no reason for anything to change locations in space. But it isn't; and so there are net gravitational forces on objects that cause them to move. Whether the attraction of two objects "wins" over the expansion tending to separate them depends upon the situation.
For a simple way to picture this sort of thing, consider a big rubber sheet with two marbles on it. Give one a nudge towards the other (its peculiar velocity), and then start stretching the sheet (the expansion of the Universe). Will they collide? Depends on the peculiar velocity, rate of stretching (expansion), etc. But it's certainly not the case that they always won't.
Now, so far as I know, intersteller distances are measured by the light year; Alpha Centuri is ~4 light years away, etc.
Well, actually, parsecs (and kiloparsecs and megaparsecs) are what tend to be used, for mainly traditional reasons. But it's a straightforward unit conversion.
The problem is this: You can point the hubble in any direction, and get an equally old image. Further, if you take a deep enough image, you can (theoretically) take an image of the Big Bang itself (or X million years after it, whatever).
In practical fact, you can't see back to the Big Bang, for a number of reasons. The first is that until a few hundred thousand years after the putative Big Bang, the Universe was opaque to radiation. Photons were simply too unlikely to pass much of any distance through the Universe without scattering off a charged particle of some sort. After that point, the Universe became transparent to photons. Consequently, that's as far back as you can see -- with photons, anyway. But you're right that you can see this change of state in the Universe (the so-called "surface of last scattering") in any direction you look, and in fact that's what astrophysicists are looking at when they map the cosmic microwave background radiation.
The other thing that prevents you from seeing all the way back to the Big Bang is that as the Universe expands, light is redshifted (basically, its wavelengths are stretched out with the expansion). That's why we have to look in the infrared band for these distant galaxies, and that's why the light we observe from the surface of last scattering is in the microwave band. Light emitted at times closer and closer to the putative Big Bang is redshifted by larger and larger degrees, approaching infinite redshifting at the Big Bang itself (when the scale factor of the Universe, describing the expansion of space relative to today, is 0). So even if the surface of last scattering wasn't there, there'd be a practical limit to just how far back one could see, based on just how low-energy (long-wavelength) of photons one could detect and interpret.
The paradox to me, is that this means the Big Bang can be conceptualized as a the outer edge of a sphere that surrounds us. You can, with the telescope, image in any direction in all three dimensions, and your limit wrt distance in any of those directions is the big bang. So the big bang is the edge.
The Big Bang occurred everywhere. It occurred where you're sitting, where I'm sitting, and where Zaphod is sitting.
Imagine some event -- say, the change of state that I described above, referred to as "decoupling", when the Universe became effectively transparent to photons, where before that it was opaque. This happened basically everywhere at once -- as the Universe expanded, densities and temperatures dropped until the scattering probabilities fell low enough. This happened everywhere, including right where you and I are now. But the photons that were around here then are long-gone now. They've been flying off in different directions since then. Similarly, the photons that were 10 light years away aren't around us either: the time they've had to fly, times the speed of light, is a long way from here. If you think about it, the photons you're going to see are ones that started out on a shell that's centered on us, with a radius equal to the distance light could travel in the time since decoupling (it's a little more complicated than that because of the expansion, but that's the basic idea). At any later time, from 1 second to 1 billion years later, that shell will be larger.
So that's why we see a given time in the history of the Universe as a shell around us. It's not because these things (like the surface of last scattering, or the Big Bang itself) really are shells, but simply because that's all we can see. The photons that started at points interior to that shell aren't anywhere near us now; they've had enough time to propagate further than the distance between us and their starting points. The photons that started at points outside that shell haven't had enough time to reach us yet.
Hope this clears things up some . . .
I don't think it's anything deep -- just that "often" is not the same as "usually". If polls are wrong a sixth of the time, it's not crazy to call that "often". (I haven't read the article, so I don't know whether it says that or not -- I just took 100% minus your quoted figure of 84% correct. But it's irrelevant to this comment)
And yes, I'm a physicist.
So am I. Your characterization of Feynman vis-a-vis Hawking is silly, I think.
As you suggest, Hawking is indeed considered to be quite smart, but to have made contributions that haven't been that major to physics as a whole. Such concepts as the Hartle-Hawking equation, black hole evaporation, etc., have been quite interesting to people working in comparatively narrowly-defined areas; that plus their removal from unambiguous observational testing makes them at most curiosities to most of the physics community.
That's a pretty far cry from the contributions of Feynman. His work on QED, weak interactions, superfluidity, and the makeup of hadrons are each individually closely tied to experiment, and all of that work related to issues that nearly all theoretical physicists spend at least some time in their careers considering. Hell, pulling Feynman rules out of interaction Lagrangians, and using the diagrams that follow for solving perturbation expansion problems, are now staples not only of particle physics, but of solid state theory as well. He was tremendously influential. Nothing Hawking has done compares in its influence.
To be honest, it seems sad to me that these are the only sorts of ways in which you can imagine regular people being affected.
Tell us, what's so "awesome" about the data Hubble's provided so far, since it went live in 1990? How has it impacted your life since then (aside from giving you neat wallpapers)? How will it impact the lives of your grandchildren (aside from giving them neat wallpapers)? How has Hubble benefited you aside from the "wow that's neat" effect?
Well, I'm not the person to whom you were responding, but I'll answer this for myself: without the FOS on the HST, we would not have had two independent teams confirming each others results in the course of determining the eventual fate of the universe. Yes, that's affected me greatly. You may chalk that sort of effect as nothing more than a version of "wow, that's neat." But if so, I can only wonder whether you've ever experienced love in your life, since loving someone and having them love you doesn't result in cancer cures or faster cars either -- but it has a huge effect on us nonetheless. Various astronomical results, including some from the Hubble, have affected me in ways a hell of a lot more profound than the most recent sexy-but-ultimately-meaningless gadget or computer game.
Note that I'm not arguing in favor of keeping the Hubble going; I'm not addressing that at all. I'm merely responding to what seems to me to be a rather sad perspective on what it means to have an effect on lives. Have you ever heard a talented orator give the St. Crispin's day speech from Henry V? Did you really not feel an excited chill when you learned that the atoms that make us all up were at one time contained in a star that supernovaed? That latter one will humble me with awe decades after I've forgotten there ever was an iPod. What kind of effect does this stuff have on us? Nothing, and everything.
for example, feynman no doubt did some great physics, but he gets much, MUCH greater recognition over two other guys who did the same work (tomonaga and schwinger, they shared the nobel prize)
You're correct that Feynman was a more dynamic speaker/teacher, etc. But I think it's a bit of a jump to say that that's the only reason why he gets more attention than Schwinger and Tomonaga. For starters, they didn't all do the same work, even on QED. It's true that all three arrived at equivalent formalisms for calculating amplitudes, but that's not the same as saying they did the same work. Have you thrown away Feynman diagrams and straightforward perturbation expansions and instead tried to do things the way Schwinger did? It's a bitch! As a famous quote of the time went, "Feynman shows you how to do it; Schwinger shows you that only he can do it." And that had a lot to do with the eventual predominance of Feynman's perspective, and thus his getting more recognition than Schwinger or Tomonaga.
Furthermore, while I can't speak to Tomonaga in this regard, Feynman made a major splash in a much broader spectrum of physical investigations than Schwinger did. The work on QED was simply one of many arguably Nobel-worthy accomplishments of his. That, too, contributes to his being paid more attention to than Schwinger and Tomonaga.
Of course, you could argue that these are only things that matter to the cognoscenti; they don't explain why Feynman is more recognized by the general public. But I would claim that contrary to what physicists, and geeks who like physics, think, the general public is pretty oblivious to physicists entirely. They've heard of Einstein; they might have heard of Hawking. That's pretty much it, though. We think of Feynman as famous; the average person on the street has never heard of him.
So while I would agree that Feynman's dynamic personality, excellence in presentation, etc., is important in the way he is remembered by those who are aware of him at all, at least equally important is the fact that he did a ton of amazing new physics.
The same person who said just about everything else of importance: James Brown.
And of course, I should know.