Re: midsummer puzzle: about those clocks

From: louisnews Newstrom (louisnews@comcast.net)
Date: Fri Aug 23 2002 - 15:00:53 MDT


From: Charles Hixson <charleshixsn@earthlink.net>

> Lets set up those clocks a bit differently than usual. Lets set
> one of
> them in motion such that on inertia it will eventually complete a
> circuit of the universe

The travelling clock will approach with a time ahead of the local
clock. However, it is running slower than the local clock, so it is
losing time. It's time will match the local clock right as it passes.
As it pulls away, it will be behind the local clock. The next time it
approaches, it will again be ahead of the local clock.

That last part sounds impossible. It seems that if you had a large
enough telescope, you could keep an eye on the clock, and it would have
to still be behind when it came back.

The solution to this seeming paradox is to realize that there are more
than one image of the clock. As you watched the clock recede into deep
space, it would take longer and longer for it's light to reach you.
Eventually, someone would tap you on the shoulder and say "here it
comes again!". You would still be watching the image in deep space.

While the distant image would show an old time, the local image of the
clock would have the correct time. If you kept watching the image in
deep space, you would eventually see it meet up with the local clock,
and both would have the same (long-ago) time that you watched it pass
by at.

---
Louis Newstrom
louisnews@comcast.net


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