Galileo Galilei was born on February 15, 1564 in Pisa, Italy. Galileo studied medicine at the University of Pisa but his real passions were in mathematics and natural philosophy. His general contributions helped to revolutionize the field of astronomy. He helped to initiate the concept of relativity. His and other scientists’ views were being condemned by the church because they contradicted those of the Bible. Since he held his viewpoints very highly he was forced to publicly renounce everything that he wrote in the Dialogue concerning the two greatest world systems. Officially, he was no longer able to publish in Italy by order of the Pope. Later he was put under house arrest until his death on January 8, 1642 in Arcetri (near Florence).

Galileo Galilei can be credited with so many accomplishments during his lifetime. He helped to make telescopes very popular. Galileo also made them an intricate part of the field of astronomy. With his telescopes he saw the moons of Jupiter, sunspots, and craters on the moon. He published his astronomical findings in the book Message from the Stars. Galileo believed in and promoted the heliocentric model of the Milky Way Galaxy that was proposed by Nicolaus Copernicus. The heliocentric model of the galaxy had the sun at the center with the Earth the other planets orbiting it. This was in stark contrast to the church accepted Earth centered (geocentric) model of the galaxy. He published his observations and beliefs in the book Dialogue concerning the two greatest world systems that he later had to publicly renounce. He can also be remembered for his theory regarding free fall. It stated that if any two objects are dropped at the same time, they will fall at the same rate. This experiment was performed by dropping various size objects at the same time from the leaning tower of Pisa.

Along with all his other great scientific accomplishments, Galileo Galilei also was the first person to propose the idea of relativity. Galileo thought that a state of uniform motion (also known as free motion) was as good as any other. He said that the relative uniform motion (moving or at rest) of two sailing ships do not affect the laws of motion in the two ships. To quote the book Spacetime Physics, "The simplicity of the Galilean Principle of Relativity lies in the equivalence of the two Earthbound frames and the symmetry between them." (Wheeler, page 55). From what Galileo described, it is possible to infer that he meant there would exist an inertial reference frame (or a frame of rest) in each ship with respect to the other ship. For example, if an object is dropped from a height on ship one it will appear to follow a straight line on ship one. Meanwhile on ship two, ship one’s object appears to follow a parabolic path. The same results will be seen from ship one if something is dropped on ship two. The concept that everything is relative was first formulated by Galileo.

Galileo Galilei created and discovered many things that have made modern science more effective. Galileo also helped to sprout the basic ideas of relativity well before Einstein was even born.