This process is broken down into seven layers; Application Layer, Presentation Layer, Session Layer, Transport Layer, Network Layer, Data Link Layer, and Physical Layer. When a person communicates to another person on a network the information passes through these layers.
Ptolemy was an astronomer and mathematician. He believed that the Earth was the center of the Universe. The word for earth in Greek is geo, so we call this idea a geocentric theory.
Johannes Kepler (1571-1630) Nominated by Michael Mosley, writer and presenter of Trust Me Iâm A Doctor. Kepler was the person who made sense of astronomy. He realised, following in the footsteps of Copernicus, that the Sun is not the dead centre of the Universe and that the planets go round in ellipses. He was a wonderful, weird character: incredibly short-sighted and yet he gazed at the stars.