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Nova: The Elegant Universe and the String Theory

 
 
littlek
 
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Reply Thu 30 Oct, 2003 07:46 pm
aha, follwed the NOVA link:

Six-dimensional Calabi-Yau shapes can account for the additional dimensions required by superstring theory. There are 6 dimensions bundled up into pockets - could those also hold the missing mass?
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sozobe
 
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Reply Thu 30 Oct, 2003 08:10 pm
I suppose they could. It's just a matter of compatibility of theories... physicists who are working on finding dark matter are not generally going into the stuff of parallel universes et al... they are trying to plumb the depths of THIS universe.

The main thing, which it looks like the program did a good job of emphasizing from what fishin' said, is that this is all a theory. With theory, you can just create anything to fill in gaps, by definition. Oh, that wouldn't work, hmm, I guess we need to add one more dimension.

The physicists who are looking for dark matter are operating in an entirely different sphere. One experiment has found that neutrinos have between __ and __ of mass. Other experiments have found that the universe has __ of mass, total. Various objects found in the universe have been measured. Things don't compute... where's the rest?

It's all specific and measurable, and theories are meant to get you to something else specific and measurable. ("Well, since this made this happen, I wonder if this could make this happen. If it did, it would indicate this, so let's go ahead and test it and see what happens.")

So the physicists who are interested in dark matter would say to the string theorists, show me some proof of a string existing and we will go from there. Until then, they just don't have much to do with each other. The whole either/ or thing.
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littlek
 
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Reply Thu 30 Oct, 2003 08:11 pm
yep, I can see that. Thanks Soz.
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fishin
 
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Reply Fri 31 Oct, 2003 09:08 am
sozobe wrote:
The main thing, which it looks like the program did a good job of emphasizing from what fishin' said, is that this is all a theory. With theory, you can just create anything to fill in gaps, by definition. Oh, that wouldn't work, hmm, I guess we need to add one more dimension.


They did do a lot of stressing that it is more of a philosophy than a science at this point stating several times that String Theory isn't provable and probably won't be any time soon.

But like dark matter theory, you have a mathmatical formula that seems to work and within the formula you have "X" and "Y". The quest becomes figuring out just exactly what "X" and "Y" are.

One group searches for dark matter, another searches for strings.
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sozobe
 
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Reply Fri 31 Oct, 2003 09:25 am
But dark matter has something concrete to go on. The X is theory, Einstein's, how much mass the whole Universe should have, but Y is specific, how much mass the known things in the universe have. Subract y from x and you should get zero, and you don't. So physicists who are looking for dark matter (not just theorists, experimentalists too) are taking X as true and know a lot of Y, but are looking for more of it.

It's like saying evolution and creationism are both theories. That's true, I guess, but one is based on objective truths and the other is more internal -- the theory says so so that means it's true.

Again, not to completely debunk string theory or anything, it just hasn't gotten to a useful place yet, not clear if it ever will.

More basically -- string theory is about math, dark matter is about physics.
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rosborne979
 
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Reply Fri 31 Oct, 2003 09:32 am
Hi K,

As I understand it, there are two distinctly different "dark" things out there. One is dark matter. Clumps of material (usually called baryonic matter) which we can't see like burned out stars, gas clouds, neutrino's, MACHO's, and black holes (though the holes are not necessarily "matter" any more).

The other dark thing (the more interesting one) is dark energy. There appears to be an "essence" to the universe which we do not understand yet, which causes the acceleration of the universe and adds to its overall mass.

The ratio of parts is fairly well agreed upon at this point: 73 percent dark energy, 23 percent cold dark matter, and only 4 percent atoms.

http://antwrp.gsfc.nasa.gov/apod/ap030212.html
http://antwrp.gsfc.nasa.gov/apod/ap030303.html

Strings are predictions of a mathematical model which attempts to combine QED with GR. Because they are proposed as the structural element of EVERYTHING, even energy, they would not be thought of as a "piece" of the puzzle when it comes to identifying the missing mass in the Universe, because everything is made up of strings, dark matter as well as dark energy and any other dark thing we can think of.

Best Regards,
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Butrflynet
 
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Reply Fri 31 Oct, 2003 08:26 pm
The more I read about this, the more confused I get.

It appears to me that scientists needed something to resolve the incompatibilities of quantum mechanics and relativity when they disintegrated into chaos when explaining the existence of black holes.

It looks to me like the urge to find an equation to settle the disruption between the two theories was the priority and strings were invented to heal that disruption. The vast emptiness between quarks and strings in the power of 100 scaled images model is just the cushion of time needed before advancement in optics proves or disproves the string theory.

Is there anything known to science that would lead one to the theory of strings other then the need to bridge that gap between quantum mechanics and relativity with some kind of equation?
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rosborne979
 
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Reply Fri 31 Oct, 2003 09:38 pm
Butrflynet wrote:
Is there anything known to science that would lead one to the theory of strings other then the need to bridge that gap between quantum mechanics and relativity with some kind of equation?


Well said Butterfly, and no, there is nothing else known to science which implies strings, other than the math needed to unify QED with GR. And that's the hitch; science normally proceeds from observation or deduction (within the natural world) to theory. But in this case, it's our own theories which become our world (and perhaps an un-natural world at that).

String Theory needs to produce a testable hypothesis, otherwise it's not science. It's here that the line between science and philosophy is most strained; we need to be careful not to confuse the model with the measure.

Luckily the best minds in physics are aware of this connundrum, and are understandably wary. String theory has been around for a long time, but it's still just speculative (maybe for good reason).

Best Regards,
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littlek
 
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Reply Fri 31 Oct, 2003 11:55 pm
Thanks rosborne. More to think on.....
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jpowell
 
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Reply Tue 18 Nov, 2003 04:27 am
I just wanted to point out that this series is available for viewing at the pbs website.

http://www.pbs.org/wgbh/nova/elegant/program.html

I thought it was great. For those of you who haven't seen it you should check it out.

{edit: I noticed a link to the pbs site in the first post. But I think it was just offered for viewing within the last couple of days. So I added the link.}
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neil
 
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Reply Thu 20 Nov, 2003 02:52 pm
Hi Sosbina: Would a billion times increase in nutrino flux Kill all us humans? Neil
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