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Feb25-12, 05:34 PM
P: 381
Quote Quote by suprised View Post

And no, GR ist not just the theory of a spin 2 graviton; string theorists know this probably better than anyone. How often needs it to be repeated that gravitons corresponds to "small ripples on a water surface" and not to the whole ocean including vortices etc.

The amount of misconceptions, desinformation and plain nonsense propagated here is really staggering!

In quantum field theory, the quanta like photons and gravitons are just momentum and energy of the fields. Of course you need the entire fields to do the work although what you can measure are simply the photons and gravitons but the fields which you take as the ocean underneath the "small ripples on a water surface" need to be active with the properties it needs.

Now in the case of our spin-2 gravitons discussions. To be sure I understood the concept. Let me explain it to you. What they meant when they say spin-2 field over flat spacetime equaled curved spacetime and gravity is not that spin-2 gravitons is enough to pull off those trick. But the ocean or gravitational fields derived from a quantum gravity has the properties and right coupling to pull of the gravity act. Then the spin-2 gravitons are just manifestation of this hidden gravitational fields. Therefore to avoid confusion. I think the proper things to say is instead of:

"Spin 2 gravitons + flat spacetime = General Relativity". One must say this:

"Spin 2 gravitons (with underlying gravitational field produced from excitations of strings or LQG or others) + flat spacetime = General Relativity."

Are we clear on this now. You guys used the former descriptons all throughout hence you confused even others like "surprised". Right?