Does light travel in a straight line or waves?
Light waves travel in straight lines. You can detect them with your eyes, and also with instruments such as cameras. They are reflected by mirrors and change direction when they travel from the air into glass or water. Light travels very fast.
Does light travel in a straight way?
Light travels in straight lines primarily due to the fact that light is a wave. However, light can change its path (away from a straight line) when it is incident on certain obstacles. This effect is commonly reffered to as diffraction.
Does light travel in straight lines forever?
Ordinarily, no, light will continue on its path forever unless it runs into something. Now, this said, very powerful photons (i.e. gamma rays) can spontaneously transform into particle-antiparticle pairs.