a logical shot....

[meemoe_uk]

Hey, here's a chance to shoot me down by giving me an endless list of reasons why this is the dummest idea of all time!

Could netrinos actually be the missing graviton particles?
In my nieve mind they qualify in most respects..
1. hardly interact with matter at all.
2. Vast quantitys of sun's netrinos are spose to flow through the earth and throughout the rest of the solar system.

Only drawback is that current theory reckons non nuclear-active bodys don`t produce enough of them.

So how loose is current theory on cold-body netrino production? 100% certain no way?

[Ambitwistor]

Originally posted by meemoe_uk
Could netrinos actually be the missing graviton particles?

Eh? No. Neutrinos are spin 1/2 particles; gravitons are spin 2, by definition.

What do you mean, "missing" gravitons, anyway? Did you mean dark matter, instead of gravitons?

[cucumber]

why are gravitons by definition spin 2??

(don't bother to answer if you can't do it
in a few lines, I'm just curious...)

thanks.
cucumber.

[Ambitwistor]

[QUOTE]Originally posted by cucumber
why are gravitons by definition spin 2??

Because gravitons come from the quantization of general relativity, and in GR the gravitational field is given by a rank-2 tensor (the metric). A rank-2 tensor corresponds to a spin-2 particle.

It's possible to construct theories with particles other than spin 2, but they don't behave like general relativity does in the classical limit.

[meemoe_uk]

What do you mean, "missing" gravitons, anyway?
as far as I know, no-one has been able to detect them. Give us a link that prooves beyond reasonble doubt otherwise ( not just some optimistic speculation on some new result ).

[Ambitwistor]

Originally posted by meemoe_uk
as far as I know, no-one has been able to detect them.

Of course no one has ever detected them. It is certain that nobody ever will. Theory predicts this: it's extremely difficult to directly detect a gravitational wave, which would be made up of an astronomical number of gravitons, because gravitational waves are so weak. In light of that, directly detecting a single graviton is out of the question. However, it may be within the reach of future experiment to have some indirect evidence of them (much as we have indirect evidence of gravitational waves today), e.g. by photon dispersion experiments or something. It depends on what theory of quantum gravity is true.