Does light travel in a straight line?

Does light travel in a straight line?

Does light travel in a straight line?

• Answer 1 :

Yes, it does, at least in flat space-time under most circumstances.

In curved space-time (or for that matter in flat) it travels a path called a geodesic. This is still a straight line to it, the light, but in another reference frame one may measure it as curved.

It can be made to deviate from a straight line, such as in a medium. Most of the time, like when it enters a sheet of glass, it just looks like it's bent. However, you can get a real, obvious curve using something like acoustic-optical modulation.

To explain why, we'd have to go into quantum electrodynamics. It's fascinating but probably TMI for this question.

• Answer 2 :

Depends on how you look at light.

Light can be assumed to move spherically as in we assume they are purely waves(Huygens principle), or assumed to move linearly as in we assume they are purely particles(Newtons principle).

Of course light is a combination of both.

So to break it down, normal light seems to disperse spherically at distances very small from the source and then seem to travel linearly when the source is far away(which very much is Huygens principle).

• Answer 3 :