Here’s a delicious contradiction: sometimes, light is a wave and sometimes it behaves like a stream of particles.

Science tells us that light is electromagnetic radiation that can be seen with our human eyes. It spans wavelengths from about 400 to 700 nanometres, transporting energy through space at a constant speed of 299,792,458 meters per second (186,282 miles per second). (That's fast. It is also, far as we can tell, the universal speed limit.)