# [time-nuts] UTC and the speed of light?

Bill Hawkins bill at iaxs.net
Tue Aug 30 19:02:47 EDT 2011

```The question has both a frequency and a counter part, as does any
clock.

The frequency shift with gravity has been nicely addressed by tvb
and others.

The counter of the frequency is subject to phase shift caused by the
speed of light and the distance to the measured source. Each counter
must be given an initial value of time in order to be called a clock.

There can be no correction done at the source of the frequency. The
user must make a distance/speed of light correction for his (rarely
her) location.

Try this old analogy. There is one clock in the center of town. It's
pendulum is the only source of frequency. If you can't see the clock,
then the bell is your only source of time. Different citizens at
different distances will not hear the bell at the same time because
of the speed of sound.

If some of the citizens had astoundingly precise wristwatches, really
fast reaction times, and different large distances from the bell, they
would be surprised when they met at the monthly Gentleman's Time Club
gathering to see that their watches did not match. Eventually Isaac
Galilei would discover the speed of sound and deduce the reason for
the offsets. Then the gentlemen would periodically meet under the
clock tower to set their watches, and reckon the distances to their
homes by the time offset.

Bill Hawkins, who recently read Neal Stephenson's "Quicksilver."

```