* Light can bend: Light doesn't always travel in a straight line. It can be bent (refracted) when passing from one medium to another, like from air to water. This is why objects appear distorted when partially submerged in water.
* Light can curve: Light can also be curved (deflected) by strong gravitational fields, as predicted by Einstein's theory of general relativity. This is called gravitational lensing, and it's observed around massive objects like stars and galaxies.
* Wave-particle duality: Light exhibits both wave-like and particle-like properties. In some cases, it behaves more like a wave, which can spread out and diffract around obstacles.
Instead of "proof," we have strong evidence supporting the idea that light travels in a straight line under normal circumstances:
* Pinhole cameras: A pinhole camera demonstrates that light travels in straight lines. Light from a source enters the pinhole and projects an image onto the opposite wall. The image formed is an inverted projection of the source, indicating that light travelled in straight lines from the source to the pinhole and then to the wall.
* Shadows: Shadows are formed because light travels in straight lines. An object blocking light creates a shadow, indicating that the light couldn't pass through the object and continued in a straight line.
* Laser beams: Lasers produce highly focused beams of light that appear to travel in straight lines.
Conclusion: While the idea of light traveling in a straight line is a useful approximation in many situations, it's not a universal truth. Light can bend and curve under certain conditions, and its behavior is ultimately governed by the principles of wave-particle duality and general relativity.
