In science, the question of what light is reduces to what it does, but what it does is often inexplicable. Even after centuries of study, physics still can’t explain why light:
1. Doesn’t fade. All physical waves fade over time, by the second law of thermodynamics, but light doesn’t. A photon that took a million years to hit a screen gives the same result as one just made.
2. Has a constant speed. The speed of a wave depends on the medium it travels through, but light travels at a constant speed in empty space for no apparent reason.
3. Is like a wave and a particle. Waves aren’t particles nor are particles waves, but light is sometimes like a wave and sometimes like a particle, which doesn’t make sense.
4. Always takes the fastest path. A particle can’t know the fastest path to any destination in advance, but light always finds that path, somehow.
5. Defines its path when it arrives. A particle can’t pick the path it took to a destination when it arrives but light seems to do just that, which is very strange.
6. Can reveal an object it didn’t physically touch. In a purely physical world, it should be impossible to detect an object without touching it, but light can do exactly that.
7. Seems to vibrate outside space. Light waves vibrate as other waves do, but according to the equations that describe it, do so in a dimension outside our space, which is odd.
Most scientists assume that light is physical, but it often behaves in non-physical ways. For example, current physics says that light is particles that can also be waves, but physical particles can’t do that. A water wave doesn’t arrive at a point like a particle, but light does. A particle can’t take many paths at once like a wave, but light seems to. Physical waves don’t act like particles, and particles don’t act like waves, so how can light be both? Surely science can decide if light is a particle or a wave?