String Theory: no unique solution for the Universe?

[pmbryant]

From the NY Times: Sep 4 2003

One Cosmic Question, Too Many Answers

By DENNIS OVERBYE


Call it the theory of anything.

Einstein once wondered aloud whether "God had any choice" in creating the universe. It was his fondest hope that the answer was no.

He and subsequent generations of physicists have hoped that at the end of their labors there would be one answer — a so-called Theory of Everything — that would explain why the details of the world are the way they are and cannot be any other way: why there was a Big Bang, the number of dimensions of space-time, the masses of elementary particles.

For 20 years, physicists have lodged those hopes in string theory, a mathematically labyrinthian effort to portray nature as made up of tiny wriggling strings and membranes, rather than pointlike particles or waves.

(snip)

The hope was that when all was said and done, there would be only one solution to the theory's tangled equations, one answer corresponding to only one possible universe. But recent progress in string theory paradoxically seems to leave physics further than ever from that dream of a unique answer. Instead of a single answer, the equations of string theory seem to have so many solutions, millions upon millions of them, each describing a logically possible universe, that it may be impossible to tell which one describes our own.

(snip)

But the same calculations confirmed that string theory could have a vast number of solutions, each representing a different universe with slightly different laws of physics. The detailed characteristics of any particular one of these universes — the laws that describe the basic forces and particles — might be decided by chance.

(snip... much, much more...)

More: http://www.nytimes.com/2003/09/02/science/space/02STRI.html

[ewagner]

1. Cool

I'm no physicist but I was following this years ago.

Thanks for the link....great recreational reading..............

[brokensymmetry]

2. Great article!

I really enjoyed reading it - thank you!

[On the Road]

3. This Part Was New to Me:

"In the long run," he said, "the universe doesn't want to be four-dimensional. It wants to be 10 dimensions."

So sooner or later, the loops will unravel like a tangle of rubber bands, passing through a succession of configurations that take less and less energy to maintain, until finally the other dimensions expand and the cosmological constant is gone.

The decay of the cosmological constant will be fatal, astronomers agree. At that moment a bubble of 10-dimensional space will sweep out at the speed of light, rearranging physics and the prospects of atoms and planets, not to mention biological creatures.

"What it leaves behind," Dr. Susskind said, "it's hard to say. Almost certainly not a livable universe."

Worse than the big crunch. Definitely a new wrinkle.

[pmbryant]

5. Yes, that seems a bit far-fetched to me

There is still no evidence that these supposed 'curled up' dimensions even exist, and now string theorists are suggesting that they will destroy the universe as we know it.

I wish there were a bit more string theory skepticism expressed in that article.

But otherwise it was quite interesting.

--Peter

[Dudley_DUright]

4. Thanks Peter

I missed this one. I keep forgetting to check the science section on Tuesday. I saw string theorist Ed Witten give a talk at the 100th anniversary American Physical Society meeting in Atlanta in 1999. The guy has to be one of the most brilliant people on the planet. I agree with him (as most physicists do) that the anthropic principle is kind of a cop out.

Dr. Witten said he also disliked the anthropic principle. "I continue to hope that we are overlooking or misunderstanding something and that there is ultimately a more unique answer," he wrote by e-mail.

[pmbryant]

6. Major cop out indeed

The whole appeal of string theory in the first place, I thought, was the hope that it would produce a unique solution that explained all physics. If they abandon that, they don't have much left to stand on, I would think.

--Peter

[kixot]

7. It's very easy to criticize an idea

When you don't know or understand the mathematics from which they conclude.

[pmbryant]

8. LOL

Indeed.

But one doesn't need to fully grasp the mathematics to understand that String Theory has not been able to make any predictions yet, as far as I know. So skepticism should be the default attitude.

String Theory is fascinating stuff, though. :bounce:

--Peter

[midnight armadillo]

10. Without predictions...

...string theory is little more than elegant mathematics. Heck, I hesitate to consider it to really be science. Then again, I'm an experimentalist, so I may be biased against the eggheads ;-)

[ewagner]

9. Admittedly, I don't understand the math

I do however, understand that the concept of 10 dimensions is mathematically the only way that string theory holds together. Is that also your understanding?

[papau]

12. 11 dimensions (10 plus time) was required to solve a math problem

That was interpreted as meaning we are 4 dimension shadows of 11 dimension reality.

Folks did not like this and got curled up dimensions (that do not cast a shadow ? - this is fun to play with - since by definition there are no size limits on the dimensions - or are there? - and expanding from 4 dimension to 11 dimension is an expansion in what sense if the 4 dimension is a "reality" of the 11 dimension only with 7 dimensions curled up and without meaning - and are we calling the fudge factor now needed for the fudge factor cosmological constant a result of the curled up nature of the 7 dimensions? - it really is fun - and it is making more folks in science appreciate and accept religion - you can decide if that is a good! )

I have a math resume - which does not mean I travel in these circles - but does mean I try to keep up. And I believe the fellow that said there are no predictive results from string theory that can be tested is correct. But the solution is always to get more data - so lets build a really really big atomic research device!

:-)

:toast:

:-)

[bigtree]

11. memo to Blake

Instead of a single answer, the equations of string theory seem to have so many solutions, millions upon millions of them, each describing a logically possible universe

The theory recalls William Blake's description of religious philosophy:
"Man's perceptions are not bound by organs of perceptions.", he wrote.
"The desire of man being Infinite, the possession is Infinite and himself Infinite. He who sees the Infinite in all things sees God.

He felt that every particle of matter had inherent motive that originated from one supreme entity. Still, there has been no discoveries that have proved the existence of that originating force.