Why Light Has No Net Charge & Can Be Bent by Gravity

[chrisych]

I know that the light has no net charge and so it can't be bent by magnetic and electric fields but why there is no net charge for light.

Actually, light is propagating by varying both of these fields. These variations should make a net charge for light.

In addition, someone said that light can be bent by gravitational field. Why?

 

[Doc Al]

I know that the light has no net charge and so it can't be bent by magnetic and electric fields but why there is no net charge for light.

Actually, light is propagating by varying both of these fields. These variations should make a net charge for light.

Why do you think that? Just because charges have fields associated with them does not mean that wherever there's a field there must be charge. After all, a point charge has a Coulomb field everywhere around it, but the charge only exists in one place.

In addition, someone said that light can be bent by gravitational field. Why?

For a detailed answer, you'll need to learn some general relativity. In a nutshell, GR predicts that energy/momentum is what couples to gravity, not just mass (as in Newtonian physics). Read the last paragraph of this for a taste: http://math.ucr.edu/home/baez/physics/Relativity/SR/light_mass.html"

In the relativity forum we have many experts who can give you more, when you are ready for it.