If bosons don't interact, then how can gravity affect the path of light?

[nomadreid]

One says that bosons do not interact with one another. However, the presence of a gravitational field, and hence of gravitons (bosons) (assuming they exist), changes the probability of where a photon (boson) appears, which is the same sort of interaction as two fermions, no?
And, the contrary: mass-energy tells space how to bend, and this bending of space is essentially the gravitational field, so isn't this an interaction of photons and gravitons?

 

[Meir Achuz]

"One says that bosons do not interact with one another."

Who says?

 

[Regel]

Perhaps what one means is that bosons do not obey the Pauli exclusion principle.

This needs to be compared with fermions: Even non-interacting (i.e. no many-body interactions) fermions repel each other due to the Pauli exclusion principle. Bosons on the other hand do not repel in case of no many-body interactions.

 

[Vanadium 50]

Let's not guess what the OP means; let him explain it himself.

 

[andrien]

mass-energy tells space how to bend, and this bending of space is essentially the gravitational field, so isn't this an interaction of photons and gravitons?

I think there should be a feynman diagram for it?

 

[Bill_K]

I think there should be a feynman diagram for it?

Sure. One choice for the electromagnetic Lagrangian is

L = - ½ A^μ,νA_μ,ν = - ½g^μσg^ντA_σ,τA_μ,ν = - ½(η^μσ + h^μσ)(η^ντ + h^μσ)A_σ,τA_μ,ν

from which one can pick out the vertex that couples two photon lines and a graviton.

 

[nomadreid]

Oops, my apologies to all who responded; I misread an article ( "The Computational Complexity of Linear Optics", by Scott Aaronson and Alex Arkhipov), which outlines experiments using non-interacting bosons -- and I misread the way this phrase to mean that all bosons were like that. But after the challenge by Meir Achuz, I re-read it and understood my mistake. My thanks to Meir Achuz (like mea achuz~100%?), Regel, Vanadium 50, adrien, and Bill K.

 

[Meir Achuz]

My thanks to Meir Achuz (like mea achuz~100%?)

You have outed me. Now you know my test score, and my safah.