Arcadian Functor

occasional meanderings in physics' brave new world

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Marni D. Sheppeard

Friday, February 20, 2009

Good, Bad and Ugly

People who hear that I am interested in physics often say to me that they would like to know more about String Theory. Although not articulated, the implication is usually that there must be Only One String Theory. In reality, string theorists come in several flavours: good, bad and ugly. For example, our friend kneemo is a good string theorist, who recognises that the so called physical predictions of main stream String Theory are probably just plain wrong.

Then there is mottle, who recently said:
String theory is one theory, it predicts many possible vacua (Lorentz-invariant or dS-invariant solutions to its equations of motion), and we live in one of them.
Well, at least this statement settles any doubt one might have had that the bad string theorists might be willing to alter their physics a little to fit the facts. Clearly, the facts don't matter to them. Ugly string theorists include people who boast loudly that they are not string theorists at all, but are not very convincing.

9 Comments:

Blogger L. Riofrio said...

For a while it was hard getting over all the publicity that string types have made for themselves. String theory makes physical predictions?

February 20, 2009 4:37 PM  
Anonymous Anonymous said...

Hi Louise. I have been making phone calls to Australia regarding my visa application. Another week ends, and it turns out that the initial enthusiasm of the Sydney people has waned somewhat. They assured me they could find out something about the progress of my application, but that was before they checked any details. Now it would appear that they cannot, in fact, tell me anything about my application. One really begins to wonder whether knifes have been aimed at certain backs. I sure know what that feels like, anyway.

Remote Kea

February 20, 2009 6:11 PM  
Anonymous Anonymous said...

What do you get when string theorists party?

Entanglement.

***

What do you get when you give a string theorist plenty of rope?

A Gordian Knot.

***

What happens when two string theorists marry?

10^500 children across the multiverse, but all with differing amounts of dark energy.

***

What's the difference between a good string theorist and a bad one?

The good one predicts nothing; the bad one predicts everything!

***

How many string theorists does it take to change a light bulb?

Up to 10^500, depending on how Calabi-Yau moduli are stabilized.

***

What happens when two string theorists have an argument?

Branes collide.

February 21, 2009 12:13 AM  
Blogger Matti Pitkanen said...

Dear Anonynmous. You seem to have an unrespectful attitude towards string theorists and you deserve a healing treatment.

I order you to write on toilet paper 10^(500) times "Super string theory is the only possible theory of everything!".

February 21, 2009 4:31 PM  
Anonymous Anonymous said...

How many string theorists does it take to play hide and seek?

10^500 + 1 ... so that there exists at least one universe with two people in it.

Remote Kea

February 21, 2009 5:43 PM  
Blogger L. Riofrio said...

What did the string theorist say when caught by his wife in bed with another woman?

"I can explain everything!"

Have courage, the NASA job required a long security investigation.

February 22, 2009 5:41 AM  
Blogger kneemo said...

It is said that papers in string theory are published at a rate greater than the speed of light. This, however, is not problematic since no information is being transmitted.

-H. Kleinert

February 22, 2009 12:24 PM  
Blogger antimatter33 said...

I have to say here all string theory is bad. The attempt is a roll back to Democritus, an ambitious plan. Yes a new idea for matter is needed to incorporate gravity into the general scheme of physics. It remains resolutely alone.

One should recognize this. The domination of quanta should be questioned - the lesson is that gravity is geometry and we should simply accept this. One cannot have a background, because the background IS physics. This was why string theory was doomed from the beginning - the fiction that gravity is just a spin-2 Boson led everyone astray.

But how did simple quanta come to describe the entire theory? In fact QM is about Hilbert (state) space and measurement. That quanta may be incorporated is not its essential feature - it is complementarity.

And so strings were doomed from the start, because the real question is not how to make gravity accomdate quanta, but how to make it susceptible to a complementary description. The failure was bound to be in the vacuum - this was obvious in 1984 when I learned about it. They tried to update Democritus, but made the same error, of putting something "in the void".

There should be a description of matter in which wave behavior is intrinsic to the vacuum, even in the case of curvature. That is the real definition of background free.

You cannot do that but putting one thing inside another. As we learn from special relativity, wave propagation is not a matter of ether, but of geometry - propagation is intrinsic to the geometry of the world, and this should show up explicity in any new proposed theory of matter. String theory fails for the simplest of reasons, because from the start it is a classical idea with no possible classical analogue. This is nearly identical with the failure to find any actual physical vacuum.

The lesson is to adapt field theory to gravity, and that gravity should adopt from field theory its locality (commutation on a spacelike surface) and well-defined energy. Even classical GR does not have this simple property. That's the main clue.

-drl

February 23, 2009 6:26 PM  
Blogger Mitchell said...

Louise, that's the best string theory joke I've ever heard.

February 28, 2009 8:07 PM  

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