Back to the original question !
astronomerjim wrote:
So as we all know, as we approach the speed of light, time slows down...
Actually it doesn't slow down, it just appears to slow down.
Consider a clock in front of you ticking away in time with your wrist watch.
You look at your watch and then at the clock and they are knocking up the seconds at the same rate.
But what happens if the clock is moving ?
There is now a delay between one second and the next.
You will look at the clock initially to synchronise with your watch at say 12:00:00
Then when your watch reaches 12:00:01 you look at the clock but there is a delay due to the time taken for the signal to reach you from the clock.
As the clock moves away from you nearer to the speed of light the delay increases.
Hence you will think it is running slow in comparison to your watch.
An observer travelling with the clock would use exactly the same argument to say that your watch was running slow compared to his Clock.
Two assumptions are made here:
1: The speed of light is constant.
2: Neither the clock or your watch are accelerating
Note: The same is true for mass and length using the arguement above.
They do not increase/decrease dependant upon speed but remain constant.
They just appear to change....it would be nonsense otherwise.