Gravity and String Theory

• January 23rd, 2009, 10:16 AM
(Q)
Gravity and String Theory
I must admit to knowing very little of string theory, especially the math.

Why is it that gravity is thought to be weak due to the fact that it must "struggle" through the torus shaped "hidden" dimensions of space, and the other forces do not struggle to the same degree, hence are stronger forces?

Does this question even make sense?
• January 23rd, 2009, 12:10 PM
organic god
i think the reason that gravity can be considered comparitively weak, is that when a pin is put on the surface of a planet of large mass, it can still be picked up by a tiny magnet.
• January 23rd, 2009, 12:21 PM
(Q)
Quote:

Originally Posted by organic god
i think the reason that gravity can be considered comparitively weak, is that when a pin is put on the surface of a planet of large mass, it can still be picked up by a tiny magnet.

I understand that gravity is weak. However, I'm trying to understand why the other forces, after breaking symmetry in the Big Bang, do not undergo the same issue as gravity, from a string theoretical perspective.
• January 24th, 2009, 06:44 AM
Liongold
Spontaneous symmetry breaking. Superstring theory by nature has supersymmetry in it, to get rid of tachyons. The spontaneous symmetry breaking is simply described by "struggle through the torus shaped "hidden" dimensions of space".

However, please don't take my word for it. I am not a physicist myself and know little of the math. However, spontaneous symmetry breaking is the likeliest possibility.
• January 24th, 2009, 09:58 AM
(Q)
Quote:

Originally Posted by Liongold
Spontaneous symmetry breaking. Superstring theory by nature has supersymmetry in it, to get rid of tachyons. The spontaneous symmetry breaking is simply described by "struggle through the torus shaped "hidden" dimensions of space".

However, please don't take my word for it. I am not a physicist myself and know little of the math. However, spontaneous symmetry breaking is the likeliest possibility.

Thank you, sir. But, that doesn't really explain why gravity is so weak compared with the other forces, which is what I'm trying to understand.
• January 24th, 2009, 10:49 AM
Liongold
Quote:

Thank you, sir. But, that doesn't really explain why gravity is so weak compared with the other forces, which is what I'm trying to understand.
In a string theory of context, I've given my best guess for it.

However, nobody knows why the forces are so different. Supersymmetry tried to explain this with spontaneous symmetry breaking, but supersymmetry failed as a theory (though there are scientists hoping for it to be true).

I personally believe it is because the forces act on different criteria. Gravity acts on mass, which can be small compared to a charge, which, in comparison to a particle's mass, is huge. The electroweak force works on leptons, which have significantly smaller mass than hadrons but equal charge, while the strong force works on quarks, which are equal in mass but smaller in charge.

Further, gravity and electromagnetism have infinite range which decreases with distance, as does the weak nuclear force; the strong force, however, has asymptotic freedom i.e. the farther they are, the stronger the force; after a certain limit, the force is constant.

Why is the most difficult question to answer with such vast differences.

I just read my third paragraph again, and it strikes me that the weak and strong nuclear forces have odd parallels, as if they fit. The strong force works on particles with mass equal to leptons but smaller charge; the weak nuclear force acts on particles with mass smaller than hadrons, which quarks collectively make up, but has a larger charge.

Don't you think that's a little odd?