Ok if I was going the speed of light traveling away from earth and I looked back what would I see? Would I see the same sight until I slowed down? I know this is physicly impossible for several reasons but work with me here?

Under those conditions I believe you would see an unchanging snapshot until you slowed down.

Let's take a different approach. If you were travelling from Earth at 161,000 mile/sec, time would pass more slowly for you in the ratio of 2 to 1. That is, an observer would see your clocks count one second while a clock on Earth counted two.

You watch a ball being dropped from a height of 32 feet. On Earth, it will take one second to drop. The moment to see the ball's release, you start your stopwatch.

Of course, you are seeing the drop begin some time after the event, because it has taken the light that amount of time to reach you. This does not affect the example, though.

One second after you start the stopwatch (and it has counted 1/2 second), the image of the ball's ground impact has reached your previous location -- but you have moved away from it. The light will take another 6 1/2 seconds to catch up, for 7 1/2 seconds total.

For you, of course, about 3 3/4 seconds has elapsed on your watch, and your perceptions tell you that that amount of time has passed.

Now, you have watched an event which experience has taught you to take one second, and you've seen it take 3 3/4. Everything you see along your line of departure appears in slow motion, at a ratio of 3.75 to 1.

Had you not been travelling directly from Earth, but had changed course 90 degrees (across your line of departure), the image of the ball's impact would have arrived one second after you saw the release. It would still have appeared a slow fall, but less so -- only a 2 to 1 slowdown.

Hey, can someone check my math on that? I haven't done this stuff for a quarter century...

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Originally posted by TomGL2:
Hey, can someone check my math on that? I haven't done this stuff for a quarter century...

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It's been longer than that for me, but I believe that a ball dropped from a height of 32 feet on earth takes 2 seconds to fall. In 1 second it reaches 32ft/sec but it averages 16ft/sec.

Thank you, frankvan! I knew something was amiss. I was so intent on getting the other stuff right, that I confused acceleration with velocity (duh!) -- d=at²/2, right? So that's 1.414 (root 2) seconds for a 32 foot fall.

Luckily, it doesn't change anything important in the example. Thanks again!

[This message was edited by TomGL2 on 06-27-02 at 02:45 AM.]

You would see nothing. It would be all light could do just to keep up with you, so no photons would be striking your eye.

At slightly less than the speed of light you'd see a dim red spot directly behind you. As you slowed down the red spot would broaden and become lighter until it started looking like a reddish circular bubble looking out on the universe, kind of like how it looks when you peer through the peephole in the front door of your house. As you continued to slow the bubble would get wider and whiter until you stop, at which point your view would have returned to normal.

Your trip would be much more interesting if you faced forward. For due to time dilation and length contraction, you would see the entire Universe flash before you as a single point of light in a single instant of time.