# Gravitons and gravity in a asteroid-planet interaction

## Main Question or Discussion Point

Let me start by saying I know nothing and just come seeking knowledge.

I hear that a graviton has never been discovered, only theorized. True?

If so, I was thinking of how we might find one.

When planets get nailed by asteroids isn't the energy from the momentum of the asteroid getting added or subtracted to to the planets gravity?

Might there be Gravitons being created here? Antigravitons? Wouldn't it be cool if we could launch some spinning, molten spheres from the space station and nail them with BBs to see what happens?

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mgb_phys
Homework Helper
A little background - in Quantum mechanics a massless particle is needed to carry a force, the photon carries the electric force and W and Z particles carry the forces that hold atoms together.
Since gravity is a force this theory says that there must be a particle to carry it = the graviton, and predicts some of the properties of the particle.
But relativity says that gravity is just an effect of bending space and so there is no need for a particel to carry the force.

Getting these two theories to matchup has what physics has been about for the last 80 years!

Unfortunately since gravity is such a weak force the graviton, if it existed, would be almost impossible to detect directly - it would need detectors much larger than a planet! You can test some of the properties by looking at gravitaitonal waves - but these are also tricky to detect.

You can't have an anti-graviton, they are in the same class of particles as the photon (the bosons) which don't have anti particles.

mathman
A little background - in Quantum mechanics a massless particle is needed to carry a force, the photon carries the electric force and W and Z particles carry the forces that hold atoms together.
The W and Z are responsible for the weak nuclear force (beta decay), gluons are the carriers of the strong nuclear force (holding protons and neutrons together).

mgb_phys
Homework Helper
The W and Z are responsible for the weak nuclear force (beta decay), gluons are the carriers of the strong nuclear force (holding protons and neutrons together).
oops, thats why i'm an astronomer -and i think w&z have mass

pervect
Staff Emeritus
A real graviton would be a quantum of gravitational radiation, just as a real photon is a quantum of electromagnetic radiation.

Obviously since we are working on detecting gravitational radiation at all, it will be a long time before we can determine whether or not its quantized.

Don't confuse real gravitons with virtual gravitons, or real photons with virtual photons. See the sci.physics.faq on virtual particles for more info

http://math.ucr.edu/home/baez/physics/Quantum/virtual_particles.html

Basically, one often sees a lot of confusion from people who treat virtual particles as if they were real.

mathman
oops, thats why i'm an astronomer -and i think w&z have mass
They do, in contrast to the other force carriers which are massless.

Re: Gravitron

A real graviton would be a quantum of gravitational radiation, just as a real photon is a quantum of electromagnetic radiation.

Obviously since we are working on detecting gravitational radiation at all, it will be a long time before we can determine whether or not its quantized.
How does this relate to the quantum gravitational states observed at the Institute Laue-Langevin, reported in 2002?

http://www.aip.org/pnu/2002/573.html [Broken]

http://physicsworld.com/cws/article/news/3525

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Re: Gravitron

wow, you just bumped a 2 year old topic :)>
I'm new here, so ... What is the average age of other bumped topics? :)

(And I was impressed by the Institute Laue-Langevin observations.)