What do physics geeks think of Gravitons?

[History_Buff]

I'd agree there, but I think TLC is taking it to a higher level then that. Is that the best argument for it?


If gravitons do exist, what must be true about them in terms of physical characteristics?

Well, if Gravitational force only came in discrete amounts, wouldn't it have to be carried by something?

 

[Perfection]

Well, if Gravitational force only came in discrete amounts, wouldn't it have to be carried by something?

Maybe, but I dunno what about some sort of crazy discrete spacetime thing instead.

 

[col]

Graviton is just the name we give to the quantum unit of gravitational field. Maybe quantum theory is wrong and there is no quantum - but QED has had amazing success at predicting experimental results.

No pro- physicist serisouly doubts that it is GR that will have to be quantised to come into line - so we give the hypothetical quantum the name of graviton.

The graviton would have to be massless and travel at the speed of light (like the photon) - because grav forces obey an inverse square law.

 

[El_Machinae]

Everything I know about this topic, I learned from a Lee Smolin book. I don't know if he's very reputable.

 

[Perfection]

The graviton would have to be massless and travel at the speed of light (like the photon) - because grav forces obey an inverse square law.

Would it have different wavelengths and polarities like photons too?

 

[col]

Wavlengths are to do with the wave aspects of light rather than the photn aspects. Grav waves would certainly have wavelengths. Gravitons? I dont see why it shouldnt obey similar rules to photons where the energy is proportional to the frequency.

But then I dont know much about gravitons compared to GR and QED.

 

[ybbor]

The graviton would have to be massless and travel at the speed of light (like the photon) - because grav forces obey an inverse square law.

can something massless exist?

 

[Irish Caesar]

How would gravitons be observed or detected? I mean, could a detector be able to notice just one?

can something massless exist?

Why not?

Photons do.

 

[Bill3000]

can something massless exist?

Yup! A massless particle always moves at speed v = c, and has an energy-momentum relation of E = pc, as opposed to a massive particle's relation of E^2 = (pc)^2 + (mc^2)^2 ; note that in the latter, when m = 0, it reduces to E = pc.

 

[SparrowHawk95]

Graviton is just the name we give to the quantum unit of gravitational field. Maybe quantum theory is wrong and there is no quantum - but QED has had amazing success at predicting experimental results.

No pro- physicist serisouly doubts that it is GR that will have to be quantised to come into line - so we give the hypothetical quantum the name of graviton.

The graviton would have to be massless and travel at the speed of light (like the photon) - because grav forces obey an inverse square law.

This is correct. But, unlike the photon which has spin 1, a graviton would have spin 2, so it would have more degrees of freedom (different polarizations).

 

[warpus]

So if we know all the properties of this supposed graviton, why is it so hard to detect?

 

[col]

Because it doesnt have much energy.