How come that satellites can transmit information to earth?
Satellites transmit information to Earth via radio waves. Radio waves (or more generally, electromagnetic waves) are oscillations between an electric and magnetic field. They all travel at the same speed (the speed of light) although this speed can be slowed down by matter (such as air or water, see “refraction”). Sound waves are compressional, so they need a medium to travel through. Electromagnetic waves do not. At one point, it was offered up as a theory that there was a medium called the “ether”, which permeated all of space and was the medium that electromagnetic waves travelled through, although this theory was discarded and the currently accepted idea is “wave-particle duality,” meaning that electromagnetic waves can also be thought of as particles (called photons), which is also an easier way to imagine them travelling through space with no medium.
