What is the current state of efforts towards "Grand Unified Field Theory"?

Question

Do not simply regurgitate watered down layman's "String Theory" (ie, Elegant Universe)

re:joysula-if you would have qualified "some" physicists you'd have maintained a modicum or correctness ...the fact is 11th dimensional phasespaces will never be mapped,any more than "angels will be counted on the head of a pin"...and while elegant-it is not "applied" and is therefore more speculative...and many "serious" physicists do not believe it ever will be "applied"...I am more interested in asrophysics...the "inflationary theory"...z-particles and quantum mappings...than a new philosophic and esoteric physics designed for the speculations of laymen...

Answer 1

Hi gmonkai

Lets start by defining exactly what you're asking. Currently physics recognises four fundamental interactions: electromagnetism, weak nuclear interaction, strong nuclear interaction, gravity. The hierarchy of unification physics goes this way:

1). electromagnetism + weak nuclear interaction = electroweak theory (discovered by Glashow, Weinberg, Salam)
2). electroweak + strong nuclear interaction (QCD) = grand unified theory (GUT)
3). GUT + gravity = theory of everything (TOE)

Most people tend to use GUT to mean TOE, and I'm unsure if that's what you mean as well. It seems to be evident that most replies to this thread have made this mistake. If you mean GUT as written above then there's no need to talk string theory. There are a number of extended standard model theories which are candidate GUTs. The key element they share is the ability for quarks to decay into leptons (the particle group containing electrons, muons, tauons and neutrinos). This means a decay mode for the proton, hence GUT experimental investigation focuses on searching for proton decay.

If you're talking TOE on the other hand then there is a key piece of the puzzle still missing: quantum gravity. The other fundamental interactions each have quantum theories, gravity does not. A successful quantum gravity theory will point in the right direction for the TOE. So far standard quantised field theory (the approach which yielded quantum electrodynamics and quantum chromodynamics) doesn't work for gravity largely because the field (and hence the field quanta) carry energy and energy is a source term for gravity. These extra infinities aren't renormalisable (a mathematical tool used to cancel infinities). String theory purports to explain this and that but it doesn't make testable predictions - neither do brane theories yet. n-supergravity seemed promising but can't be the solution on its own, neither can SUSY.


Hope this helps!
The Chicken

Answer 2

Until string theory makes a testable prediction, it is not my first choice for a potential G.U.T. I think that the multiple extra dimensions that we can't observe are a sign that something isn't quite right with the theory. (It reminds me too much of the luminiferous ether as an explaination for some problems in classical electrodynamics) I've been working on unifying the electromagnetic and gravitational forces for a while now. I think I'm on to something good but it is going to take a lot of thought. I hope that if I can theoretically unite these two forces, the nuclear forces will fall out in the process. Personally I think most of my fellow physicists are concentrating too much on bizzare quantum mechanical theories. Most current attempts are just too complicated, they lack the beauty and elegance that nature so often displays.

Answer 3

Currently the most favored candidate for a Grand Unified Field Theory is Superstring Theory. However, there are many versions of String Theory. The most recent thinking is that each version is the theory for one possible Universe, not necessarily our own. The hunt is on for one version of String Theory that will describe our own Universe.

However, some String Theorists believe that our Universe is one tiny bubble within a Megaverse of universes. Because String Theories seems to be pointing toward the existence of a "Cosmic Landscape", where every point on this landscape represent one possible universe, i.e. a unique set of physical laws, a set number of large extended spatial dimensions, and a unique value for the cosmic constant, etc. This seems to explain why there are so many string theories.

One other worthy mentionables is this: a major breakthrough in String Theory is the development of extra higher spatial dimensions, specially the introduction of the concept of "branes".

Branes seems to have resolved alot of the mathematical inconsistencies that plagued string theories before, and provides a meaningful explanation of how our 3-dimensional world can exist within a higher spatial dimensional world, and also provide someway for us to test the correctness of String Theory.

Answer 4

i talk about this with my science friend,

i dont think we are ever going to figure it out, but the applications from trying are worthwhile

thanks for getting my back with that guy regarding free thought, and from whence democracy came,

if they had their way it would be theocracy, im not joking ive asked them if they would prefer theocracy of jesus and they almost all said yes

Answer 5

unified feild theory can only be achieved with string theory (As physicsts believe) and now i ask you do you know whats there in the string theory?? you dont know its silly for you to ask this question and comment on the theory you dont know the answer contact me you *********

Answer 6

I don't want to try to make any sense out of it