Motion is relative

notions of relativity

"The earth does move but we´re not aware of it. Tiring is more to be feared for the stellar sphere than the terrestial globe".



... observed by Galileo Galilei (1564-1642), Italian physicist and astronomer, when speculating about the earth´s rotation.

The big "c".

The velocity of light is not relative, space and time are. The velocity of light isn't just how fast light goes, it's a number somehow woven into reality itself — that is, space and time organize themselves around "c".