Relative Velocity of Photon Clock and Relative Velocity of Atomic Clock

We have a “photon clock” made out of two mirrors A and B. Photon is moving from A to B, back to A and so on. One traveling of the photon between A and B is a “tick” of the clock. We take two photon clocks. One photon clock is on the surface of the earth, second is 4200 meters below at the bottom of the mine shaft. Velocity of light is invariant on gravity; both of clocks will “tick” with the same velocity.

We take two atomic clocks. One clock we put beside photon clock on the surface and second beside clock that is 4200 meters deep. According to the relativistic gravitational effect of relative velocity of material change second atom clock will in 30 days “tick” faster as the atom clock on the surface for 1,23 x 10 -6 seconds.

General Theory of Relativity considers light moves through the space with constant velocity regardless upon the strength of gravitation. This implies that at the scale of the photon and below at the scale of Planck relativistic gravitational effect of relative velocity of material change does not exist.

 

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Wouldn't the photon paths be different because of the gravitational effect?

 

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Time really does move slower in a stronger gravitational field, it doesn't matter how you measure it. Your two photon clocks will not tick at the same speed.

 

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You have stepped on a land mine. The locally-measured speed of light is invariant in General Relativity. All bets are off when talking about someone else's (and therefore non-local) speed of light as measured by your clocks and rulers. That's when you have to shut-up and do the math.

 

A landmine indeed.

Einstein started with the constant speed of light as a postulate in 1905, but in 1911 he wrote On the Influence of Gravitation on the Propagation of Light, where we can see his ideas evolving. He gives the expression c = c0(1 + Φ/c²), which is c varying with gravitational potential. Then in 1912 he said it again when he wrote "On the other hand I am of the view that the principle of the constancy of the velocity of light can be maintained only insofar as one restricts oneself to spatio-temporal regions of constant gravitational potential". He reiterated this in 1913 when he said this: "I arrived at the result that the velocity of light is not to be regarded as independent of the gravitational potential. Thus the principle of the constancy of the velocity of light is incompatible with the equivalence hypothesis". We see it again in 1915 when he says " the writer of these lines is of the opinion that the theory of relativity is still in need of generalization, in the sense that the principle of the constancy of the velocity of light is to be abandoned." That’s on page 259 of Doc 21, sorry, I’m not sure what the original paper is called. He says it again in late 1915, on page 150 of Doc 30, within The Foundation of the General Theory of Relativity. Einstein says "the principle of the constancy of the velocity of light in vacuo must be modified.". He spells it out in section 22 of the 1916 book Relativity: The Special and General Theory where he says this:

"In the second place our result shows that, according to the general theory of relativity, the law of the constancy of the velocity of light in vacuo, which constitutes one of the two fundamental assumptions in the special theory of relativity and to which we have already frequently referred, cannot claim any unlimited validity. A curvature of rays of light can only take place when the velocity of propagation of light varies with position. Now we might think that as a consequence of this, the special theory of relativity and with it the whole theory of relativity would be laid in the dust. But in reality this is not the case. We can only conclude that the special theory of relativity cannot claim an unlimited domain of validity; its results hold only so long as we are able to disregard the influences of gravitational fields on the phenomena (e.g. of light)".

People tend to see the word velocity in the various translations without seeing the context and without noticing that he’s repeatedly referring to “the principle”. They miss the significance of “laid in the dust”, and skip over his reference to "one of the two fundamental assumptions". They don’t see that he's talking about the SR postulate, which is the constant speed of light. And they don't appreciate that Einstein didn't speak English in 1916, and that what he actually said was die Ausbreitungsgeschwindigkeit des Lichtes mit dem Orte variiert. I’ve got the original German version, and I got a German friend and an Austrian friend to translate it for me. It translates into the speed of light varies with the locality. The word “velocity” in the 1920 Methuen translation was the common usage, as in “high velocity bullet”, not the vector quantity that combines speed and direction. He was saying the speed varies with position, hence the reference to the postulate, and hence it causes curvilinear motion.

The light clock down the mine "ticks" slower, because the light goes slower.

 

Farsight

light velocity is invariant of inertial system and of gravity.
That is the fundation of SR and GR.

yours Zweistein

 

Read what Einstein said.

 

Better yet, read what a modern graduate-level textbook on GR says.

 

Farsight and rpenner.......there is no book of physics where it would be written that light velocity is depending on gravity......if yes that you know, please inform us.

 

That is the flat-earth interpretation of Shapiro delay which is covered in may GR textbooks.
Locally, the speed of light in vacuum is constant, but when measured by someone else's clocks and rulers, strange results appear as a consequence of the curvature of space-time.

Examples:
Richard A. Mould, Basic Relativity p. 255

You have to read the whole paragraph to see the very nuanced point he is making about local measurements.
http://books.google.com/books?id=lf...="shapiro delay"&pg=PA255#v=onepage&q&f=false

 

I think velocity of light is constant regardless gravity. Why should gravity diminish speed in stronger gravity ? There is no reason. When pulling out of strong gravity frequency of light change, but velocity is the same. When passing sun direction change but speed is the same.

 

Can you explain how GPS validates a change in light speed? Sure a change in time is seen based on gravity but not a change in light speed.

http://relativity.livingreviews.org/Articles/lrr-2003-1/index.html

See chapter 5.

Your argument is inconsistent with GPS.

Flat earth folks make arguments inconsistent with the scientific evidence.

 

Hi Jack

we have two options:
A ) if light velocity is constant than photon clock "ticks" with equal velocity regardless gravity
B ) if light velocity is influenced by gravity change than photon clock "ticks" with different velocity in different gravity
What you think is real ?

light speed = frequency • vawe lenght
by gravitational red shift frequency goes down and vawe lenght goes up. For me this shows gravity does not influences velocity of light, A is real B is wrong.

 

Your reasoning is consistent with the scientific GPS evidence.

I think this place is infected with flat earthers.

 

photon moves in space only (not in time)......that is the point

 

I see you are of the view that light speed in space is a constant c.

This does not work.
I have seen papers, though I did not bookmark them, dammit, that proves light speed is a constant speed in space with astronomy.

In fact, distant light star aberration, seems to show light speed is one speed in space.

So do binary stars. So does lab Sagnac and tests from moving light sources.

But, GPS does not detect the motion of the earth around the sun and not the motion of our solar system in the milky way.

So, something is wrong.

 

SR is postulated on constancy of light velocity.
Equality of inertial and gravitational mass is connecting SR and GR.
Discussing on possibility that gravity infects velocity of light put under question relatedness of SR and GR.
Gravitational red shift shows that gravity influences only frequency and not velocity of light.
This means that “thought experiment” with photonic clock is correct:
Velocity of photonic clock is invariant on gravity.
In stronger gravity photon moving between mirror A and B change only frequency and not velocity.
And this means that relativity gravitational effect of relative velocity of material change starts above photon scale.

 

It has already been pointed out to you that the local speed of light doesn't change, it is only when you try to compare the speed of light somewhere else to the speed of light next to you that you will find they are different.

Consider watching someone fall into a black hole. As you watch them they will appear to move slower and slower; if they shine a light out at you it will get dimmer as the rate of photons reaching you becomes slower. The photons also look redder as they become red shifted. The photons also seem to take longer to reach you than you would expect if space were flat, which is really just the same thing as saying time goes slower near the black hole.

This is a weird argument to be having anyway, you already accepted that the light clock will tick differently according to different inertial observers as usual in SR, why do you now think it will tick the same for different non-intertial observers? Surely it is only going to be a worse situation. If two observers are situated in different gravitational fields, they are not in the same reference frame, so you shouldn't expect them to observe the same things as each other. The frame down the mineshaft is more accelerated than the frame on the surface.

 

also in SR photon clock have same velocity regardless inertial system
a photon clock on the satelite will have same velocity as the photon clock on the surface
sure atom clock velocity is different

 

So you think in SR photon clocks appear to tick the same to all observers? The photon clock and the constancy of the speed of light to all observers is one of the most common ways time dilation is demonstrated in SR.

Have you seen diagrams like this?

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Because the speed of light is measured to be the same by all observers, the two clocks have to be seen to tick at different rates; the light has further to travel in the moving clock, so if it goes at the same speed the ticking has to be seen to be slower.