Can Time Slow Down on a Clock Due to Relativity?

[x-ecutioner]

hi there,

I just watched a documentary on the discovery channel.

Steven Hawking's into the universe, and i have two questions.

How can time slow down on a clock, if a clock is influenced by the movement of gears or automated by circuitry? An example would be a faster clock in space than on earth.

and

if a gigantic rocket were to be built that travels at 99.9% speed of light and time travel were to occur, how would the space crew come back to Earth and appreciate the change in time?

that documentary got me thinking

thanks guys

 

[magpies]

For the clock example I would say pressure change is what caused the time differences.

 

[Geigerclick]

There is a relativistic rocket FAQ on this site.