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The Trouble with Physics
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by kudoushinichi
on 2007-11-27 08:49:50
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Has anyone read this book by Lee Smolin? It's quite an eye-opener. The way Smolin describes what is the Physics community like today, especially in the States is quite worrying. From Smolin's descriptions, it seems that String Theorists are might really be on the wrong track. To take an example out from the book, Smolin pointed out that the finiteness of String Theory has not been proven (there is a paper by Mandelstam that provided 'proof' of the finiteness of the string theory, but the 'proof' provided in that paper is regarded as incomplete by mathematicians). But many string theorists continue to insist that the theory is finite although it is unproven. They will say something like 'Can you not see how beautiful the theory is?' They are believing in the theory because of its elegance although the theory might not be related to nature at all. It's like a cult now... And many physicists these days are involved in string theory to the extent that if you are working on something else other than string theory, it will be very difficult for you to get an academic job. String Theory is like the fashion in physics. And I thought fads are not the 'intellectual, smart, people' stuff... So anyway, since this is a Physics forum, I'm not supposed to delve about that too much, right? The book also explores alternative approaches to solve the fundamental problems in Physics (there are 5, according to Smolin). One that interests me is Doubly Special Relativity (Smolin admits, it is a stupid name). DSR has this crazy idea that the speed of light is not constant but changes over time. And that the speed of light is infinite at the beginning of the universe. And there seems to be some observations on cosmic rays at AGASA, that suggests that this might be true. There is another observatory, Pierre Auger Observatory in Argentina that is now setting out to improve AGASA's results and to confirm whether or not the speed of light is really constant. (I'm not going to attempt to explain what the observations are, since after the first reading, I have little understanding of it... But it has something to do with protons from the cosmic rays. Protons traveling in outer space should have energy lower than a certain value according to Special Theory of Relativity and apparently they are violating this limit according to the observations) Now that is interesting. Since if it is true that the speed of light is not constant, the consequences are profound. 1. Einstein is wrong. Or partially correct; and that the postulates of Special Theory of Relativity has to be rewritten. 2. Smolin pointed out that it may mean that there can be absolute rest or absolute motion. Since we have learned before that motion is relative, and if the speed of light is not constant, light moves relative to what? The revival of the luminiferous aether perhaps? Or maybe something else? That is my question...
Shinjitsu wa itsumo hitotsu!
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Re: The Trouble with Physics
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by
on 2007-11-27 11:47:59 (edited 2007-11-27 11:51:00)
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On Fads I define a "fad" as a transient group of related memes. Transient because they enter and leave the culture they effect, leaving no net effect. Related in that we group lots of different specific cultural memes together when we talk about a fad. They are a part of any culture, and the culture of modern physics inquiry is no exception. Unfortunately, such vague human concepts are hard for me to talk about. I like to be precise. I will say that it is clear that much of the hubbub around String theory et al is similar to that around peanut allergy. We've got very little in the ways of new unknowns and new data, compared to the 1930's! We're left with a small handful of very difficult problems. That brings be to the topic of string theory itself. String Theory The problems of string theory are well known: not yet testable, not yet mathematically satisfactory, etc. IT DOES NOT FOLLOW, however, that just because we haven't figured it out yet, we never will. I have heard arguments for and against the likelihood of finding predictable results. Much progress has been made into finding mathematical formulae that are satisfactory. If I were president of the world, I would not take any grant money away from string theorists. I would, however, grant MORE money to projects like the LHC, which will be conducting some real interesting tests very soon. You should not use the word cult lightly. String theory is certainly not a cult, but it does have a seemingly undeserving following of the overly dedicated sort. This is, indeed, a problem. One solution would be for these people to follow Feynman's example! Doubly Special Relativity I think you are mistaken about DSR. This theory adds one postulate on top of special relativity: that the Planck energy is a universal constant, just like the speed of light. It does not imply that these constants change over time. In fact, it seems to really state the opposite. By the way, there is some criticism that DSR is not a new theory at all. It strikes me, too, that this is nothing more than a re-orientation of terminology, not producing a new way things ought to work (WTOTW). The WTOTW is, in my opinion, the only meaningful result of a theory, and thus a good way to judge them. If two theories produce the same WTOTW, when we do a test, the results will support both theories equally. It's a matter of applying Occam's razor from there! Varying Speed of Light The VSL is a neat idea, and could explain a lot if true, but the evidence is stacked up against it. For example, Richard Feynman made strong argument against the theory based on simple (and universally agreed upon) observations on the solar system. Just for fun, though, let's think about what it would mean if the speed of light did vary, in our imaginary video game. In our video game, we play a photon, and we get to aim ourselves in a direction, and fire from some point. Then we sit back and watch our photon body fly through space and wrap around the screen at the edges forever. Sounds like a fun game!!! The speed of light is an editable variable at the beginning of each level, and so is the window size. Speed is a measure of distance units over time units. The units of distance are measured in pixels, and time is measured in milliseconds. Let's say we play the game and notice it takes 2 seconds to wrap around the screen once pointed in the up and down direction. Now, on level 2, we double the speed of light variable. Now things happen twice as fast, because the clock in the computer is fixed, that is to say, the units of time are fixed. So, the result we see is that things travel a greater distance (more pixels) in a given amount of time. What if, say, we shrink the game window by half, but use the original speed of light. That's the same results as when we doubled the speed of light! So, you see, by editing the size of space, or the speed of light, we produce the same results. Inflation theory is another theory that has the same WTOTW as VSL. It easier to accept, for purely historical reasons, and so it's the theory I'll stick with. Making up silly little theories that have the same WTOTW but are either more complex or a clever reshuffling of variables is probably a waste of time. However, if it leads to a new idea, then it's not a waste of time, so, we'll see. I think it's important for people to be honest that they've just found a new way of doing the same thing. If it's easier to teach, or easier to do mathematics with, or leads to a well rounded understanding of the WTOTW, than good times. If done for publicity, prestige, etc., it is pure evil. absolute rest, absolute motion, and the luminiferous aether Not a chance. Not a chance in hell. This is NOT how physics works at all. Please read about the Correspondence Principle. It is very important and something the laymen does not tend to appreciate. 
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Re: The Trouble with Physics
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by SuicidopoliS
on 2008-02-01 13:55:20 (edited 2008-02-01 13:57:58)
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And many physicists these days are involved in string theory to the extent that if you are working on something else other than string theory, it will be very difficult for you to get an academic job. String Theory is like the fashion in physics. And I thought fads are not the 'intellectual, smart, people' stuff... What the hell is this for b...? There's still plenty of fundamental Quantum research to be done (and yes, people are working on that), solid state physics (super conductivity, blablabla...), astronomy has a LOT of open questions, high energy physics, bio-physics, acoustics, nuclear physics, etc., etc., etc... There's still SO much to be done, that has nothing to do with string theory at all, and believe me, people ARE working on that, too. Wake up, dude, go have a look at some universities and the different active departments. Loads of work for physicists that don't want anything to do with String Theory. I'd just like to add that *if* String Theory is a cult, it's only so because people like you (no offense, just an observation), make it one. Go talk to some physicists and see what they think of it, and how much of a cult it is to them. .oO° Life's THE CURE, the rest are details! °Oo. |
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Re: The Trouble with Physics
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by kudoushinichi
on 2008-02-01 19:29:30
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Argh~ Don't attack me! That's what Smolin says in his book. I'm just quoting what he says.
Shinjitsu wa itsumo hitotsu!
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Re: The Trouble with Physics
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by
on 2008-02-02 10:48:03 (edited 2008-02-02 10:50:56)
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SuicidopoliS, maybe Kudou wasn't able to articulate clearly, but I think it what he means is that today it is harder to get a job on the cutting edge of physics compared to 50 years ago. Government spending on particle physics research in the U.S. has been dramatically reduced in the last 2 decades, for example. In some ways, it might be said that the U.S. has in some large part abandoned physics research. This is no doubt as disturbing to Smolin as it is to me. So, part of "the trouble with physics" is lack of funding. Valid point. As for cults, I don't think mathematicians who sneak into the physics department late at night to study possible applications of their work should be labeled such. They seem more like romantics to me. However, if they are sucking up all the funding, then I can see how this might be perceived negatively by Smolin and company.
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Re: The Trouble with Physics
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by SuicidopoliS
on 2008-02-11 03:33:14
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Yeah, the lack of funding is know also in my small little European country... I'm guessing it's no better in my neighboring countries. But i got set off by the statement that if you want to pursue a career in Physics, you're almost obliged to do so in String Theory. Here, this is most definitely not true. Funding is, as you said, already hard to get, no matter what Physics you're doing, and down here, it's even more difficult if you want to study String Theory (there seems to be a lot of Elementary Particle Physics going on, though). Recently, i had a discussion with a professor of mine, who told me that the U.S. is trying to attract young, European Physicists, for the simple reason that they don't have enough of their own anymore. He said it's difficult to make a living out of it in the U.S., even more so than down here (kind of aknowledging what Smoling says), so a lot of people prefer pursuing a career in, i dunno, say... some big company. And i can't help but being somewhat bothered by all this talk about String Theory these days. It reminds me of how people who don't know the first about Quantum Physics try to use it to "explain" some "supernatural phenomena" and stuff... (I recently saw 10 minutes of "What the bleep do we know?", and couldn't take it anymore... That movie has absolutely zero to do with Quantum Physics.) I feel the same thing is going on with String Theory, and it p... me off. But maybe i'm just seeing things that aren't really there, and getting upset way to easy. Wouldn't be the first time. .oO° Life's THE CURE, the rest are details! °Oo. |
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Re: The Trouble with Physics
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| Regarding the cult thing on String Theory, I agree with Gendou, but I see why Smolin calls it a cult. On this interview to PBS, Sheldon Glashow says: "there is today a disconnect in the world of physics. Let me put it bluntly. There are physicists, and there are string theorists. Of course the string theorists are physicists, but the string theorists in general will not attend lectures on experimental physics. They will not be terribly concerned about the results of experiments. They will talk to one another." Later he says "in other words, we don't listen to them, and they don't listen to us. We can't understand them, and what we do is not of any direct interest to them". That helps to understand why Glashow left Harvard, since in his words they have a "very strong group of string theorists" and he's quite skeptical on that matter. |