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

In summary, the author thinks that there should be a diagram to show the interaction between photons and gravitons.
  • #1
nomadreid
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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?
 
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  • #2
"One says that bosons do not interact with one another."

Who says?
 
  • #3
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.
 
  • #4
Let's not guess what the OP means; let him explain it himself.
 
  • #5
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?
 
  • #6
I think there should be a feynman diagram for it?
Sure. One choice for the electromagnetic Lagrangian is

L = - ½ Aμ,νAμ,ν = - ½gμσgντAσ,τAμ,ν = - ½(ημσ + hμσ)(ηντ + hμσ)Aσ,τAμ,ν

from which one can pick out the vertex that couples two photon lines and a graviton.
 
  • #7
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.
:blushing:
 
  • #8
nomadreid said:
My thanks to Meir Achuz (like mea achuz~100%?)
You have outed me. Now you know my test score, and my safah.
 

1. How can gravity affect the path of light if bosons don't interact?

The reason gravity can affect the path of light even though bosons don't interact is because gravity is not a type of boson. It is a fundamental force described by the theory of general relativity. This theory states that gravity is caused by the curvature of spacetime, and all objects with mass (including light particles, which have no mass) are affected by this curvature.

2. Does this mean that light particles are immune to gravity?

No, light particles are not immune to gravity. While they do not have mass, they still have energy, which can be affected by gravity. This means that light particles will follow the curvature of spacetime caused by massive objects, just like any other object with energy.

3. How does the curvature of spacetime affect the path of light?

The curvature of spacetime caused by gravity can be thought of as a "bending" of the fabric of spacetime. Light particles follow a straight path through this fabric, but because of the curvature caused by gravity, their path appears to be curved to an outside observer. This is similar to how a straight line drawn on a curved surface appears to be curved.

4. What evidence do we have that gravity affects the path of light?

There is a significant amount of evidence that gravity affects the path of light. One example is the phenomenon of gravitational lensing, where light from distant objects is bent as it passes near massive objects. This has been observed and confirmed through various experiments and observations, such as the bending of starlight near the sun during a solar eclipse.

5. Are there any other forces that can affect the path of light?

Aside from gravity, there are no other fundamental forces that can directly affect the path of light. However, light particles can also be influenced by other forces, such as electromagnetic forces, which can cause light to be reflected, refracted, or absorbed. These forces do not directly change the path of light, but can change its direction or intensity.

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