Why Pendulum as a clock do not shows, what General Theory of Relativity predicts?
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From: Sam Wormley on 28 Nov 2009 16:11 Enes wrote: > On 28 Lis, 20:54, Sam Wormley <sworml...(a)mchsi.com> wrote: >> Enes wrote: >> >>> Which clock is good to measure time? >>> Does it depends of time only and not of gravity? >> Use a clock (an accurate clock) where orientation does not >> matter. Space based atomic clocks come to mind. >> >> See: Relativistic Effects on Satellite Clocks >> http://relativity.livingreviews.org/open?pubNo=lrr-2003-1&page=node5.... > > Btw, Sam, > in http://en.wikipedia.org/wiki/Pound-Rebka_experiment > > was orientation matter or not ? What do you think, Enes?
From: BURT on 28 Nov 2009 16:20 On Nov 28, 1:11 pm, Sam Wormley <sworml...(a)mchsi.com> wrote: > Enes wrote: > > On 28 Lis, 20:54, Sam Wormley <sworml...(a)mchsi.com> wrote: > >> Enes wrote: > > >>> Which clock is good to measure time? > >>> Does it depends of time only and not of gravity? > >> Use a clock (an accurate clock) where orientation does not > >> matter. Space based atomic clocks come to mind. > > >> See: Relativistic Effects on Satellite Clocks > >> http://relativity.livingreviews.org/open?pubNo=lrr-2003-1&page=node5.... > > > Btw, Sam, > > inhttp://en.wikipedia.org/wiki/Pound-Rebka_experiment > > > was orientation matter or not ? > > What do you think, Enes?- Hide quoted text - > > - Show quoted text - The pendulum is falling but with weight that is full and straight down as it swings. Mitch Raemsch
From: Enes on 28 Nov 2009 16:38 On 28 Lis, 22:11, Sam Wormley <sworml...(a)mchsi.com> wrote: > Enes wrote: > > On 28 Lis, 20:54, Sam Wormley <sworml...(a)mchsi.com> wrote: > >> Enes wrote: > > >>> Which clock is good to measure time? > >>> Does it depends of time only and not of gravity? > >> Use a clock (an accurate clock) where orientation does not > >> matter. Space based atomic clocks come to mind. > > >> See: Relativistic Effects on Satellite Clocks > >> http://relativity.livingreviews.org/open?pubNo=lrr-2003-1&page=node5.... > > > Btw, Sam, > > inhttp://en.wikipedia.org/wiki/Pound-Rebka_experiment > > > was orientation matter or not ? > > What do you think, Enes? "Pound subtracted two experimental results: (1) the frequency shift with the source at the top of the tower (2) the frequency shift with the source at the bottom of the tower" What do you think, Sam? Was there any orientation of this experiment or not? Sam, what do you think about vertical direction ?
From: Sam Wormley on 28 Nov 2009 17:04 Enes wrote: What do you think, Enes? > > "Pound subtracted two experimental results: > (1) the frequency shift with the source at the top of the tower > (2) the frequency shift with the source at the bottom of the tower" > > What do you think, Sam? > Was there any orientation of this experiment or not? > Sam, what do you think about vertical direction ? There is a difference in gravitational potential between the top of the tower (further from the center of mass of the earth) compared to the bottom of the tower (closer to the center of the earth). You really should read this, Enes: http://en.wikipedia.org/wiki/Pound-Rebka_experiment Pound and Rebka set up their experiment as a variation of Mössbauer spectroscopy.
From: Tom Roberts on 28 Nov 2009 18:53
Enes wrote: > [a pendulum clock] > You can see and hear as it works: > tik...tak, tik..tak, tik..tak (in polish !) > When there is less gravitation: > tiiiiik..........taaak, tiiiiik..........taaak.... > The time is quite different, than GR predicts. > Why? Because a "pendulum clock" includes a pendulum, a support, a mechanism to count swings of the pendulum, AND THE EARTH. You keep forgetting that last part: the earth is an essential component of a pendulum clock. If you change the relationship between the earth and the pendulum (e.g. by moving the pendulum relative to the earth [#]), you have a DIFFERENT "pendulum clock". Once calibrated, each "pendulum clock" measures time in accordance with GR, but when you use several DIFFERENT "pendulum clocks" and try to assert they are a single "pendulum clock" then you get errors like above -- don't do that. I put "pendulum clock" in quotes, because that name omits essential aspects of the clock, such as the earth. [#] Ignoring the movement due to swinging; I'm talking about major changes, such as from valley to mountain or to orbit in space. Note that GR accurately predicts the period of a pendulum, including variations in its period with its position in a gravitational field such as that of the earth. This, of course, involves measuring the period with a good clock. Note also that GR predicts that good clocks located at different gravitational potentials, or moving rapidly relative to each other, will not remain synchronized. That is, when their tick rates are compared they are not equal. This is all in accordance with the theory, and does not mean these clocks are not good ones, it just means that your NAIVE expectations about clocks are not valid in GR; indeed, your NAIVE expectations are not valid in the world we inhabit, either. Tom Roberts |