String theory on the way out?

[SusanB-M1]

I have just been reading eijah's thread on 'Is gravity fundamental?' and wondered whether to add this on the end as it only needs a sort of yes/no answer. However, I've decided to make it a separate one.

My Monday reader is almost at the end of 'The Elegant Universe' by Brian Greene, and I am almost at the end of a talking book called, 'The Trouble With Physics' by Lee Smollen. I do not actually understand them, but having also listened to some Richard Feynmann lectures - also without understanding but great interest! - I have a vague sort of gist. I have really enjoyed all of it.

Lee Smollen seems to think that, although the string theorists have devoted many years and careers and money to their subject, the results have been of limited use. Of course, hindsight's great, but I wonder what the opinion of physicists here is. Are you pro or anti string/superstring theories? Do you think they will be the best answer in the long run? Or will the M theory, which seems to be the elusive theory of everything, win out?

 

[fuelair]

Hard to say since string theory is mathmatical constructs which seem to explain things but which do not prove anything and may not be the only way of explaining what they explain. Don't think they are given up on yet, but there are a number of persons here with more physics background/deeper physics background than I! Hopefully they will start chiming in soon!!

 

[Dancing David]

The issue that I see as a non-physics person who has read extensively in popular science and some not so popular is that string theory is itself very complex. One part of it is the Calabi–Yau manifold^WP, and the issue with that is that the 'strings' as they vibrate can take an incredible number of possible shapes, trying to determine which shapes give you the properties you want is very daunting as they are not infinite but still huge in manifestation.

And that is just one potential set of solutions that can be brought to bear in string theory.

Now as Lee Smolin says there are 2⁵⁰⁰ possible variations of string theory that would mean sorting them out is a huge task.

Now some very smart people are working on this and are finding ways to hopefully sort through categories of string theory and study just the fruitful ones, of course they don't really know which ones are going to be fruitful or not. Either way some cool math is being developed.

 

[TubbaBlubba]

Was string theory ever on the way in, aside from in popular science magazines?

 

[plumjam]

Yeah, it's about time they wound it up.

 

[TubbaBlubba]

Doesn't seem like they had a clue in the first place anyway.

 

[!Kaggen]

~snip~
Now as Lee Smolin says there are 2⁵⁰⁰ possible variations of string theory that would mean sorting them out is a huge task.~snip~

Sounds a bit like my fishing experiences with the tackle tangled up and all.......

 

[gnome]

Something I wanted to comment on--the more you drill down into physics and cosmology, the more you move from the intuitive to simply "what mathematical model predicts observations best?"

Sometimes the mathematics lends itself to some kind of intuitive summary, but do not mistake the summary of the model for the phenomenon itself. Unfortunately, a cool way of describing the math is often reported as the science itself.

If "string" or "M-Theory" is replaced, it is unlikely to be with anything more approachable by someone who isn't in the field.

 

[TubbaBlubba]

If "string" or "M-Theory" is replaced, it is unlikely to be with anything more approachable by someone who isn't in the field.

"Replaced"? What do you mean? String theory is an alternate way to describe particles compared to the standard model, but doesn't predict anything on its own, no?

 

[tsig]

The issue that I see as a non-physics person who has read extensively in popular science and some not so popular is that string theory is itself very complex. One part of it is the Calabi–Yau manifold^WP, and the issue with that is that the 'strings' as they vibrate can take an incredible number of possible shapes, trying to determine which shapes give you the properties you want is very daunting as they are not infinite but still huge in manifestation.

And that is just one potential set of solutions that can be brought to bear in string theory.

Now as Lee Smolin says there are 2⁵⁰⁰ possible variations of string theory that would mean sorting them out is a huge task.

Now some very smart people are working on this and are finding ways to hopefully sort through categories of string theory and study just the fruitful ones, of course they don't really know which ones are going to be fruitful or not. Either way some cool math is being developed.

They're still all tied up in knots.

 

[sol invictus]

Now as Lee Smolin says there are 2⁵⁰⁰ possible variations of string theory that would mean sorting them out is a huge task.

The problem is, the universe doesn't have any particular obligation to be convenient.

Consider the following example from biology. Suppose you know the sequence of 500 amino acids that make up a protein. Question: what's the stable configuration that protein will fold itself into?

Very roughly speaking, at each join between two amino acids the molecule can fold in one of four ways (left or right, front or back). That means you have 4⁵⁰⁰ possible configurations. And that's just for one protein.

The moral? Simple rules lead to enormous complexity, and that's the way the world is.

 

[Fnord]

String theories are explanations.

Explanations are not evidence.

But why am I writing this? I could be an agent of an extra-terrestrial polity that is bent on world domination, and our clever plan includes spreading disinformation regarding key scientific principles -- not that string theories are any of these, but that they are involved in the plot for which I can divulge no further information on a less than need-to-know basis.

And that's all that I can explain ... for now ...

 

[gnome]

"Replaced"? What do you mean? String theory is an alternate way to describe particles compared to the standard model, but doesn't predict anything on its own, no?

You may know more about it than I do... and mainly by "replaced" I mean replaced in popular consciousness.

 

[TubbaBlubba]

You may know more about it than I do... and mainly by "replaced" I mean replaced in popular consciousness.

Well, the standard model involves quarks (making up protons, neturons, etc), gluons (interacting between quarks), electrons (delocalized around nuclei) and photons (interact with electrons to make up all chemical phenomena of the world) as (some of) the fundamental particles (there are some others like the Neutrino) and regard "anti-particles" as particles travelling backwards in time (see Quantum Electrodynamics for more on this). The string theory replaces all of these with... vibrating strings or membranes. It sounds cool, but unfortunately it's not useful in the least at the moment, yet has been firmly put in place by popular science magazines trying to sway you with the depth of the math involved, etc. It's "not even wrong" at the moment, since it's not testable. The math works, but we can't use it for anything.

 

[SusanB-M1]

Many thanks for the interesting replies. I'll be back later today.

 

[Marduk]

Are you pro or anti string/superstring theories?

It died 20 seconds after Laird Scranton claimed it as evidence that the Dogon tribe of west mali had been in contact with Aliens

 

[Roboramma]

and regard "anti-particles" as particles travelling backwards in time (see Quantum Electrodynamics for more on this).

I may be wrong, but I thought that was just one way of looking at anti-particles which may or may not be useful.

The string theory replaces all of these with... vibrating strings or membranes. It sounds cool, but unfortunately it's not useful in the least at the moment, yet has been firmly put in place by popular science magazines trying to sway you with the depth of the math involved, etc.

Well, all the physicists studying string theory and "building" it aren't doing so simply because of popular science magazines. Clearly there's something that has drawn them to put their time and effort into creating this theory. It may not turn out to be fruitful, but of all the options available they considered it to be the most likely to bear fruit (or most interesting for some other reason, I suppose).

 

[MattTheTubaGuy]

I don't know much about string theory except that it involves very small strings vibrating harmonically, and that different harmonic vibrations are the different particles, like in a brass instrument where you can play different notes without changing the length of the tube, causing the same length of air to vibrate in different ways. (I think)
I haven't even really learnt general relativity yet (I want to though). I am a physicist (halfway through a uni degree), and I think in my lifetime developments in physics is going to be interesting. It will be interesting to see if some kind of unified theory can be created sometime. I would like to specialise in gravity, which is the last 'force', yet to be joined with the others. in GR, it isn't even a force (It is a bending of spacetime) I have no idea how string theory handles gravity, but I wouldn't mind finding out more about it.

 

[ponderingturtle]

I may be wrong, but I thought that was just one way of looking at anti-particles which may or may not be useful.

My understanding was that it was involving symmetry violation, specifically this would be CT violation, which is not full CPT violation which has not been found(I am not aware that anything assumes CPT as being inviolable, just that no one has found a case of it being violated).

 

[ponderingturtle]

Was string theory ever on the way in, aside from in popular science magazines?

Sure, it is big with the theoretical physicists.