Curious about the Graviton

[imatfaal]

Classically, this seems to be the case, under some sensible conditions we have the various energy conditions, which more or less say no negative masses or energies. Note that these conditions are added to the geometric formulation of general relativity to place sensible constraints on what we mean by a physical matter content.

 

Quantum mechanically the situation is far less clear and negative energies arise. See the Casimir effect, for example. Such effects could create "antigravity" at the subatomic scale and support exotic configurations like wormholes.

 

It is also possible that classically the energy conditions do not hold and we have exotic matter.

 

 

AJB - in one of Leonard Susskind's lectures he mentioned, as an aside, that dark energy was "merely" the idea that at huge distances gravity could have a repulsive rather than attractive effect. I wasn't sure if he was serious at all - and I havent read up on this - is this current thinking at all or a bit off the wall?

 

 

[ajb]

AJB - in one of Leonard Susskind's lectures he mentioned, as an aside, that dark energy was "merely" the idea that at huge distances gravity could have a repulsive rather than attractive effect. I wasn't sure if he was serious at all - and I havent read up on this - is this current thinking at all or a bit off the wall?

 

 

In essence this is correct.

 

Either dark energy is the cosmological constant and thus very much "classical gravity" or it is described by some scalar fields that have dynamics.

[steevey]

The way gravity is described in quantum mechanics, is that it's composed of a particle called a Gage Boson. Gage bosons are the particles which are responsible for forces being carried from particle to particle. Mathematically, they are there, however, they appear out of the nothingness of space, usually for brief moments then disappear. The Gage Bosons with mass are the ones that disappear, and the higher the mass of a Gage Boson, the briefer the existence. However, there's another catch. Mathematically, the Gage Bosons with mass, "snap back" to the particle they were emitted from, but can also get exchanged between other particles.

To explain how gravity's strength changes, it's been determined that if Gage Bosons exist, Gravities Boson has no mass, which allows it to exist indefinitely. However, as it spreads out, it gets weaker as there is less and less of a concentration of Gage Bosons. These Bosons don't "snap back" to the parent particle that emitted them. The reason Gravity's Boson is so weak, is because it's composed of a smaller amount of some type of energy than there is mass of the Boson for a force like the electromagnetic force. At least that's what I've heard.

Edited November 17, 2010 by steevey

[Incendia]

...What if they're inside quarks?<Or inside electrons...>

Edited November 18, 2010 by ProcuratorIncendia

[steevey]

...What if they're inside quarks?<Or inside electrons...>

 

What's wrong with them being inside quarks? Well I think it would violate Planck Time, which is the shortest amount of time that matters because its the time it takes from light to travel from one proton in a nucleus to the next, but other than that, I don't see why. Since quarks have a color charge, there has to be some way the forces are carried throughout them.