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Not too hard to conceive that an experiment at NIST with 2 clocks, 1 on the ground, and 1 at a metre elevation could be measured simultaneously by the far away clock
A photon has mass
How can you possibly state that the clock is changing frequency in the gp the same as the photon? Clearly a photon is becoming redshifted the further it gets from the ground, and a clock is becoming blueshifted the further it gets from the ground.
Think of it this way. The photon never changes. When it starts its journey it is being measured by a time dilated clock. So the frequency appears high. As the photon moves out of the gravity well the clocks are getting faster so that they record lower and lower frequencies. If you don't understand time dilation properly then you can get into all sorts of trouble.
Why does the far away clock need to be far away? The far away clock is a calculation tool, and only needs to be 'at' a differing gravity potential from the clock/clocks it is measuring.
@alancalverd, I did not say that photons have mass, that was Evan, whom I quoted. He is talking about photon energy/mass.
So - you agree with me that a photon released at G, when arriving at A is redshifted from A's perspective, and when arriving at F is further redshifted from F's perspective.And that a clock at G is redshifted from the perspective of A, and further redshifted from the perspective of F.
But if we move the clock from G and place it at A, the clock will be blueshifted as compared to when it was at G from A, F and G's perspective, and blueshifted further if we move the clock to F, from F and A and G's perspective.Can you confirm that we are agreed upon the above?
So - as I have been saying for last 3 years, a photon shifts oppositly to a clock in the gravity potential!Glad we've got that sorted out.Do you share this viewpoint Alan?
What NIST did, or did not do doesn't really affect the discussion as laid out in posts 26 & 27.
And if we say there was 2 clocks on the ground and clock G(a) was moved to A's position, clock G(b) left on ground also observes clock G(a) to be blueshifted.
Black holes emit x-rays and gamma rays
If you view the photons as not changing it makes it more apparent WHY both photons and clocks combine to show the effects of shift. I was trying to make it easier for you to understand.
Quote from: jeffreyH on 02/04/2018 20:58:34Think of it this way. The photon never changes. When it starts its journey it is being measured by a time dilated clock. So the frequency appears high. As the photon moves out of the gravity well the clocks are getting faster so that they record lower and lower frequencies. If you don't understand time dilation properly then you can get into all sorts of trouble. So you are saying that light itself does not gain or lose energy, and it only looks that way b/c of the clocks.(Edit: Where it may be considered that stating this as the case puts you on shaky ground with regards to the remit of GR, in that GR requires that light change energy and frequency in order to remain travelling at the constant speed of light.)So, (edited) looking at clocks, is there a possibilty that the clocks lose or gain energy in order that their frequency is changed?