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Re: Gravitational redshift and clocks



Always remember that you are comparing observers, so put one on the
ground, one at altitude. The observer at altitude counts 10 clock ticks.
How many ticks did the observer at altitude count during the "same"
interval. I put "same" in quotes, because you have to worry about how
each observer measures the interval. Let's say they communicate with a
light signal at the beginning and end of the measurement, and the
transmittal time is negligible compared with the length of time it takes
for "10 clock ticks" for the upper observer.



On Mon, 1 Sep 2003, Savinainen Antti wrote:

Hello all,
General Relativity predicts that when a light ray leaves the ground a=
nd rises
higher its frequency gets smaller (i.e., light is redshifted). The Ro=
und &
Rebka (1960) experiment confirmed the prediction. On the other hand c=
locks run
more slowly in the precence of gravity. This is related to the gravit=
ational
redshift since atomic oscillations which emit the radiation can be vi=
ewed as
accurate clocks.
Here comes my question: I understand that the frequency of light (or =
any
electromagnetic wave) decreases when it "climbs" higher from the grou=
nd. This
means that period of the wave motion increases. Is there a way to "se=
e" that
this (decrease in f, increase in T) implies that time passes faster a=
t higher
altitude? For some reason I can't see it :-). Could you come up with =
an
explanation which would be suitable at the high school level?

Regards,

Antti

Antti Savinainen
Senior Lecturer in Physics and Mathematics
Kuopion Lyseo High School
Puijonkatu 18
70110 Kuopio, FINLAND
E-mail: antti.savinainen@kuopio.fi
Home page: <http://kotisivu.mtv3.fi/physics/>


--
"Don't push the river, it flows by itself"
Frederick Perls