Re: Unification question

Mike Helland wrote:

> Is this roughly accurate:
>
> General relativity is a theory of space, time, and motion
> quantum mechanics is a theory of light and matter.
>
> Would you say then that a unified theory would have to be a single
> theory for space, time, and matter?

That is not accurate. Consider the points where General relativity and the
quantum theories are at least tangently in agreement.

First What is General relativity? It is a classical theory for the force of
gravitation that works over very-very large distances.
The theories of quantum mechanics are theories of the strong, weak, and
electromagnetic forces. All of these theories deal with time, space,
matter, light, motion, all that you mentioned in different ways. In GR
space-time is the mediator of the gravitational force. It is seen as a
classical continuum compleat with nasty singularities. In say
electromagnetic theory space-time is fixed and a-priory flat in most
problems. Some times when a really strong gravitational field is involved
a different metric has to be used. This would be the case near a black
hole.

The difference between general relativity and the quantum theories is that
it works on such huge scales. Furthermore it is a classical theory in
essence. The equations of general relativity do not give us a probability
that a photon will follow one path or the other. They say that a beam of
light will bend by this many arcseconds exactly. General relativity
contains nasty singularities called black holes. These are, as classically
described, also not compatible with quantum mechanics.

What is needed to unify general relativity and quantum theory is a quantum
theory of gravitation. Like every other theory of a fundamental force it
will have to work for both free energy and mass, matter and vacuum, from
v=0 to v=c. It will have to take in to account the action of the other
forces and how they alter the future probability of an interaction. A
tested, generally accepted, quantum theory of gravity will bring
gravitation into the QM fold.

The real conflict lies in how to quantize gravity.

If you ask a string theorist they will say that gravity cannot be
satisfactorily explained except as part of a unified theory like string -
M-theory.

If you ask a canonical quantum gravity theorist they will say that gravity
doenot care about the exact form of of the other forces only their total
energy-momentum contributions.






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"...we advanced from the telegraph to telephones to e-mail?" -Mr ef'n
conductor- George Carlin. www.geocities.com/hontasfx

.

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