When I freeze water in an ice cube tray in my freezer they expand slightly. Their weight remains the same therefore density has reduced. When I put these ice cubes in a glass of water they float because of the lower density. A small portion of the cube rises above the surface of the water...
Ok thanks. So if take off in my spaceship and zoom around the universe at a velocity close to the speed of light then come back to Earth will all of my school friends be older than me?
From what I understand, the speed of any object in the universe can only be measured relative to another object in the universe. . . .
If this is the case then how can we say time slows down for an object traveling at super high speed. Who is to say which object is moving at super high speed...