Which theory or field can explain this?

[Christian Grey]

Suppose I am in a room and light(photons) from the light bulb reach my eyes, or I am outside light(photons) from the sun reach my eyes and I am able to see the objects around me.

I want to know what factors affect the path of photons like temperature, gravity etc.I mean by knowing these factors I can predict the path of photon/photons.

And which theory or field can help me in this case? like Quantum field theory,Quantum mechanics etc or Condensed matter physics,Solid state physics, Particle physics,Astrophysics,Cosmology,High Energy Physics etc.

 

[A. Neumaier]

You can ignore temperature and gravity. Classical geometric optics gives you all you need to find out about the paths of light (aka photons).