Science a GoGo's Home Page Forums General Discussion Physics Forum Testing String Theory

The problem most scientists have with string theory is that it does not make any testable predictions. Now somebody thinks they may have come up with a way to do the tests. On Phys.Org there is a story about the suggestion. Scientists find a practical test for string theory.

The idea is to look for variations in the orbits of Solar system bodies that might indicate variations from the predictions of General Relativity. Specifically they want to look at the Saturnian satellites Tethys and Dione, which have different compositions and which they feel will make good candidates for checking the equivalence principle. It will take careful observations and calculations to find the differences, IF they exist.

Bill Gill

LOL all the good science writers must be on holiday and we get this garbage as science stories.

ROFL in the paper it is a proposal for a test (and not a very good one) of the equivalence principle. The claim is then that a violation of the equivalence principle would be evidence for string theory.

Now compare this stupidity to post from Marosz and the lunatic Astronomers who are going to prove GR is wrong by exactly the falsification of equivalence principle.

So falsification of equivalence principle gives us a flat absolute space or it proves string theory ... you choose because according to all these idiots it proves one or the other. Perhaps we should toss a coin for which it is

This tripe only ever sees the light of day at this time of year in the absence of real science

Now if we go to a string proponent like Lubos Motl he has set a fairly correct statement on the matter

http://motls.blogspot.com.au/2006/10/falsifiability-in-physics.html

I feel I should make a more definite statement on falsification of the equivalence principle.

If it were to be falsified no theory gets proved or installed just GR as a theory falls.

QM still stands as it does not use equivalence principle and as we have discussed before the equivalence principle makes QM and GR compatible. You will also recall many suspect that GR and QM may be incompatible it is a deep nagging doubt many scientists have which is painted over by the equivalence principle.

So what the idiots above are doing is saying if GR falls the QM is right and as string theory encompasses QM then string theory is proven .... that is a bridge to far by any science standard.

If equivalence principle is falsified GR falls and QM becomes the only theory left and any new theory must be compatible with QM. String theory is compatible but there are probably many more theories which could also meet that requirement.

Unfortunately for Marosz and the lunatic Astronomers and there flat absolute space that is not a theory that QM is compatible with so they would now need to go and invalidate QM before we could believe any of their garbage.

I always have this feeling that Motl is saying something significant, but quite often I find I'm not absolutely sure what it is. The above quote is an example. Perhaps you could shed some light on it.

What he is saying is there are some key things that string theory predicts which are highly highly unexpected. In the same way entanglement was predicted by QM and then found the chances of these sorts of weird things being predicted and then found is not remotely possible by accident

He has given you examples lets take his first

- Lorentz symmetry breaking

In 1989 Alan Kostelecký and Stuart Samuel proved that interactions in string theories could lead to the spontaneous breaking of Lorentz symmetry.

In general field theory, there are two possible ways to implement the breaking of a symmetry: explicit and spontaneous.

Explicit Lorentz violation leads to incompatibility of the Bianchi identities in string theory with the conservation laws for the energy-momentum in string theory.

So finding Explicit Lorentz symmetry breaking or that Lorentz symmetry does not break would falsify string theory.

You can pickup the background in http://en.wikipedia.org/wiki/Lorentz_symmetry


So string theory is the only current theory that not only expects Lorentz symmetry to break but describes how it would break.

Now at the moment we have sort of stayed in science language so lets pull it down to a specific concept from a layman perspective. Lets look at the anti-matter to matter in the universe ratio problem I am sure you are well aware of

http://en.wikipedia.org/wiki/Antimatter_tests_of_Lorentz_violation



See the issue here if you test anti-matter and matter and they are identical you have a problem because the ratios in the universe should therefore be exactly the same and they aren't. If they are identical then you have to break Lorentz symmetry to get a different matter/anti-matter ratio and your only theory to do that is string theory.

You can expand each item in his list in a similar way that string theory has something definite to say which is entirely unexpected from normal physics.

Does that answer your question?

Do you know of experiments under way that are making these tests? And I might point out that when you say that string theory is the only theory that takes care of these questions, shouldn't that be the only current theory? There may be new theories waiting in the wings.

And then there is the picky part of it. I don't think any of the "theories" you allude to are strictly speaking scientific theories, since they have not really risen to a level that the word theory should be applied to. They should more properly be called hypotheses.

Now I admit that I really don't like the string hypothesis. It has been around for a long time, and nobody has yet managed to match any form of it to real world observations. They still haven't coaxed the particles described in QM out of the string hypothesis. It has seemed to me to be a lot of high powered hand waving. I do admit that it has provided some really powerful mathematical techniques for use in other areas of physics.

Bill Gill

There are thousands of tests being done in many different places. Test I can think of off the top of my head

- neutrino oscillations
- neutral-meson oscillations
- clock-comparison tests on Earth and in space
- spin-polarized torsion pendulum
- hydrogen and antihydrogen tests
- comparative tests of QED in Penning traps
- muon properties studies
- cosmological birefringence
- matter /antimater asymmetry




The same is true of GR, evolution and any other current science theory. So if you want to take that stance I have no issue but be consistent.

I know you aren't a fan of string theory and your bias shows, I used to be a fan but I am now indifferent on stringy stuff.



I am using what is the science normal most call it string theory but you could argue it isn't a theory that is true.

I would also point out I have some controversial views on evolution you know that. So should I start referring to evolution as a hypotheses?

I don't because I use the science norms I try to masking my personal bias as much as possible in science discussions.



That bit is true and why I put string theory in the indifferent basket these days.

I think so; thanks