On Unification

[Jay-qu]

How is the process of unifing the four fundamental forces going? last i heard superstring theory was the go but was unpopular because of a lack of experimental evidence... i dont expect that we will master the planck energy anytime soon so does this leave superstring theory for future scientist or is there an indirect method been worked on?

[Quantum]

Well I sit back beleiving that the way ahead is Superstrings andI think that String Theory is very much active. On experimental evidence, I think we will have to wait until 2007 in CERN. :hyper:

 

Your Thoughts?

[paultrr]

I agree with that time period and also that it is very much an alive subject at the present. Also, Smolin's LQFT approach is also alive and well. There have been some experiments conducted to test the limits, so to speak. For one, as mentioned in some other posts, certain String based approaches predict Lorentz symmetry breaking. Here groups have been buzy testing just how exact lorentz invariance actually is. There is a tie in here to the size of these extra dimensions and most of the results there have tended to center around the Planck scale or less as a threshold limit on their size. However, some of the debate about large extra dimensions raised primarily after the advent of the Randall-Sundrum model is not exact talking about those compacted spaces originally out of M-Theory, but more along the lines of whole extra universes out there. These current experiments in some cases have little bearing on that issue while in others they do have bearing.

 

One of the biggest shots in the arm for string theory was its backup of Hawking radiation in the case of at least extremal blackhole solutions. LQFT has its own problems at this time one of which is rather major in that the equations have been thus far unable to actually be broken down into anything simular to the type of spacetime above the Planck scale. Most of the research there has simply involved polishing the theory itself with little actually suggested in the way of experiments to try and support the model.

 

One close tie to all this goes right back to the SM itself. The old issue about the Higgs field itself. Both string theory and the SM has that field involved. By the SM alone our best accelerators should have discovered Higg's particles and have not. This has translated to a bit of redoing of both types of theory to account for a much higher energy range at which they might be found. Current focus has been around the Tev level at present and higher.

[maddog]

I am reading a book by Michio Kaku, called "Parallel Worlds" which is giving a history

lesson on the 20th Century developments from GR of Einstein through Cosmology to

Study of Black Holes (where I am now) then into String through to M-Theory and to

whatever the latest Michio has cooked up. For LQG (Loop Quantum Gravity) check out

the book by Lee Smolin, "Three Roads to Quantum Gravity".

 

Michio Kaku was at the beginning showing the WMAP data was so accurate at predicting

the temperature of background that it verified the very small lumpiness predicted. It

predicted the flatness as predicted by Inflation by Alan Guth. He mentioned still some

problems. He hasn't got to the lack of finding the Higgs Boson yet expected to be

around 150 GeV or so (I expect him to as soon as Michio introduces Superstrings).

I forgot he did bring up the validation for not finding any Monopoles...

 

My opinion is what has M-Theory and LQG as a final TOE when they can work together.

That may be only a few years away or maybe more. We don't know yet... Greetings!

Welcome to this forum... :Alien:

 

Maddog

[Jay-qu]

my thought....

 

well even with what CERN is doing i dont think the will come close to probing the plank energy (10,000,000,000,000,000,000,000 eV) and even if they did how could you detect a superstring... but this doesnt mean i am against the theory as Michio Kaku said it is elegant...

[maddog]

I don't think they are attempting to probe the strings themselves. Just verify what

interactions are going on by using the theory. A good example is the article on the

homepage. Fermilab is doing a Neutrino experiment. Read it, I found it fascinating.

 

Maddog

[Aki]

in 2007, if we find sparticles, then that will prove the theory of supersymmetry.

[Bo]

Supertstring theory is still most 'active' and the most promising theory of everything. And it is not the lack of experimental evidence that feeds the critics (for the past 30 or 40 years or so, theory is ahead of experiment), it is the fact that it almost appears that string theory is not able to do any predictions. For example one thing people are working on is: "how to get the elementary particles we know from string theory?" now it turns out that there are probably a zillion ways to get a zillion different particle spectra out of string theory, So string theory (till now) can't say: "well we should measure a superparticle of the electron at 1.6739 TeV". (TeV is an energy scale) It is theis lack of predictable power that is just a big drawback of string theory.

 

Bo

[Quantum]

I don't think we will EVER be able to probe a string, but instead hopefully we may see a graviton escaping into a higher dimension. That would be news :confused:

[lindagarrette]

Here is an excellent article published by the New York times a number of years ago that is only slightly dated and explains a lot about space/time and quantum relationships (or lack thereof).

 

http://academics.hamilton.edu/physics/smajor/Papers/nyt_profile.html

[UncleAl]

Unification of gravitation with the Strong Force and the Electroweak Force (in turn unified Weak Interaction plus electromagnetism) is an ongoing disaster. Nobody has any idea how to do it. All attempts to date result in theory with no physical predictions.

 

(Work out the following by restoring proper spacing)

 

Planck's constant (h, enforces uncertainty in measurement; h-bar is the fundamental unit of action), Newton's constant (Big G, scales gravitation), and lightspeed (c, enforces information transfer delay) define physics:

 

? h=h G=G c=infinity

mechanics,

electrostatics: h=zero G=zero c=infinity

classical physics: h=zero G=G c=infinity

quantum mechanics: h=h G=zero c=infinity

special relativity: h=zero G=zero c=c

general relativity: h=zero G=G c=c

quantum field theory: h=h G=zero c=c

Theory of Everything: h=h G=G c=c

 

A Grand Unified Theory (GUT) unifies all forces except for

gravity using a simple gauge group such as SU(5) or SO(10) or E6.

 

Description Geometry Dynamics

of state

---------------------------------------------------------

Newtonian Mechanics | Vector in | Euclidean | Newton's

| phase space | 3 + time | laws

----------------------------------------------------------

Special Relativity | Vector in | Minkowski | Newton's

| phase space | 4 dimen | laws

----------------------------------------------------------

General Relativity | Vector in | pseudo- | Newton's

| phase space | Riemannian| laws

----------------------------------------------------------

Quantum Mechanics | Vector in | Euclidean | Newton's

| Hilbert space | 3 + time | laws

----------------------------------------------------------

Relativistic QM | Vector in | Minkowski | Newton's

| Hilbert Space | 4 dim | laws

----------------------------------------------------------

QM of black holes | Vector in | pseudo- | Newton's

| Hilbert Space | Riemannian| laws

----------------------------------------------------------