Gravitons

Son Goku

Does anybody here think that Gravitons are a more accurate description of gravity.

In other words do you think geometrodynamics is actually an approximation and Gravity is in truth the result of a spin-2 quantum field in Minkowski space-time.

I myself disagree with this and think geometrodynamics is the truth.

Professor_Fink

I think its probably to early to call the graviton theory, since we're nowhere near being able to probe it directly. We still don't fully understand the origin of mass. LEP2 at CERN could teach us alot about the Higgs particle (if its found), and that would probably help clarify matters.

General relativity does not sit well with quantum mechanics, so it doesn't fully explain the nature of gravity. I doubt that a full explanation is possible without some reference to quantum field theory.

Having said all that, I am by no means an expert. Planck2 might have more info.

Joe

Son Goku

I find the viewpoint differences between them fascinating.

For instance the nature of primordial space-time in the Spin-2 derivation is a Lorentz manifold.

As well as the different starting points for the derivation.

Also the Spin-2 derivation doesn't make that big of a deal about collapse.

breadmonkey

My God, I've never been so lost!

Professor_Fink

Hi breadmonkey,

Basically there are a number of different views of what gives rise to gravity. According to general relativity, gravity is not actually a force, but rather a warping of space-time. Free particles travel on geodesics, which are basically the path of shortest distance in space time. Matter and energy cause the space-time to be curved, so that the geodesic may not be a straight line from our point of view.

Particle physics offers another explanation; that there is an exchange particle, called a graviton, which has spin 2. This is similar to the explanation for the electromagnetic, weak and strong forces which uses photons,W and Z bosons, and gluons respectively as exchange particles.

The two theories appear to be mutually exclusive, so there is inevitably much debate over which (if either) represents what is truly happening.

Professor_Fink

D'oh. Should have mentioned that none of the other exchange particles I mentioned are spin 2.

breadmonkey

Thanks for that, makes a bit more sense now!

Professor_Fink

Any time.

aku0000

i think gravitons are a load of bull. like potental energy.
what we think of gravity is a combination of spacail warping and mater being a bit clingy.

Spear

aku0000 wrote:

i think gravitons are a load of bull. like potental energy.
what we think of gravity is a combination of spacail warping and mater being a bit clingy.

Except for the slight problem that potential energy is very real and very measurable.

cazeone

Professor_Fink wrote:

The two theories appear to be mutually exclusive, so there is inevitably much debate over which (if either) represents what is truly happening.

How then does string theory explain gravitation then, if it is a relativistic theory yet the closed strings are force mediators? Or is it only relativistic in the special not general sense?