The Naked Scientists

The Naked Scientists Forum

Author Topic: Will a photon clock run at a different rate from an atomic clock under gravity?  (Read 45818 times)

Offline amrit

  • Sr. Member
  • ****
  • Posts: 103
  • Power of science is uncompromised search for truth
    • View Profile
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.

yours amrit

Amrit, I've rephrased your title as a question to make the forum easier to navigate.  Try to do so in the future.  Thanks.  -Mod
« Last Edit: 20/05/2010 06:51:38 by JP »


 

Offline Soul Surfer

  • Neilep Level Member
  • ******
  • Posts: 3345
  • keep banging the rocks together
    • View Profile
    • ian kimber's web workspace
You are thinking wrongly here.  Time always ticks at the same rate wherever you are and however you move,  so you would not notice any change.  The difference in time scales is between the two points one inside and one outside the gravitational field and/or  travelling at different speeds. so it is the distant observer who will see the clocks ticking at a different rate. and you will only notice the difference when you get back and compare your clock with that of the distant observer.
 

Offline amrit

  • Sr. Member
  • ****
  • Posts: 103
  • Power of science is uncompromised search for truth
    • View Profile
I would not agree.
Atomic clock on the top of a high mountain runs faster than at the sea-side.
This is proved with experiment.
We will prove with experiment that for the photon clocks it is not so.
They run with the same velocity regardless to the gravity.

amrit
 

Offline graham.d

  • Neilep Level Member
  • ******
  • Posts: 2208
    • View Profile
At first sight your reasoning seems sound, Amrit. It is an extension to the simple demonstration of time dilation in Special Relativity where a stationary observer is watching light bouncing between two mirrors in a moving frame. This is interesting.

Have you any theory associated with this?
 

Offline syhprum

  • Neilep Level Member
  • ******
  • Posts: 3823
  • Thanked: 19 times
    • View Profile
"General Theory of Relativity considers light moves through the space with constant velocity regardless upon the strength of gravitation"
This is true of course but when there is a gravitational field present the light takes a curved path hence the effective speed is less than if it took the direct path.
 

Offline imatfaal

  • Neilep Level Member
  • ******
  • Posts: 2787
  • rouge moderator
    • View Profile
Amrit - a bit confused.  You are certainly right about the atomic clocks running slower due to a time dilation effect caused by gravity - but why would this time dilation effect not alter the perceived time for photon ticks as well. the speed of light will remain constant for a local observer - ie both clocks must remain in synchrony.  on the surface an observer will notice that time is slower in the mine compared to his measurement
 

Offline graham.d

  • Neilep Level Member
  • ******
  • Posts: 2208
    • View Profile
I think that the photon clock will behave the same as the atomic clock though I do not agree with Syphrum. The maths would not work out - the bending of light would not increase the path length sufficiently. It is not the gravitational field that causes the time dilation but the gravitational potential. If you have a clock at the centre of the earth there is no significant field but the clock will be seen to run slower that one (also in no significant field) close to an observer a long way from the earth. The clock at the centre of the earth is at a much lower potential; another way to look at it is that the ticks from the clock would be redshifted in emerging from the earth's gravity to reach the distant observer.

I don't think a photon clock will behave differently but I have not reasoned out why yet. I think it is to do with not being able to time photon speed remotely. It can only be done by observing events and their intervals.
 

Offline JP

  • Neilep Level Member
  • ******
  • Posts: 3366
  • Thanked: 2 times
    • View Profile
I don't think a photon clock will behave differently but I have not reasoned out why yet. I think it is to do with not being able to time photon speed remotely. It can only be done by observing events and their intervals.

I think so.  It seems to me that to compare the clocks you have to get a signal from one clock to the other.  In doing so, the signal itself is going to be distorted because it has to change from the center-of-earth coordinate frame to the far-from-earth coordinate frame, which would make the results not agree.  It would be as if you took two sheets of graph paper with different scales and gave them to two of your friends.  You ask each of them to draw a line that's 5 boxes long.  Each friend would tell you they've drawn a 5-box-long line, and only when you compare them would you be able to tell the difference.  General relativity basically tells you that your clocks are going to measure things on your local graph paper.  You have to compare them with someone else's graph paper to notice where they disagree.

Don't ask me to do the math though.... ???
« Last Edit: 19/05/2010 15:53:30 by JP »
 

Offline amrit

  • Sr. Member
  • ****
  • Posts: 103
  • Power of science is uncompromised search for truth
    • View Profile
At first sight your reasoning seems sound, Amrit. It is an extension to the simple demonstration of time dilation in Special Relativity where a stationary observer is watching light bouncing between two mirrors in a moving frame. This is interesting.

Have you any theory associated with this?

Yes I have, see our last article published in Physics Essays:
http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=PHESEM000023000002000330000001&idtype=cvips&gifs=yes&ref=no

yors amrit
 

Offline amrit

  • Sr. Member
  • ****
  • Posts: 103
  • Power of science is uncompromised search for truth
    • View Profile
Amrit - a bit confused.  You are certainly right about the atomic clocks running slower due to a time dilation effect caused by gravity - but why would this time dilation effect not alter the perceived time for photon ticks as well. the speed of light will remain constant for a local observer - ie both clocks must remain in synchrony.  on the surface an observer will notice that time is slower in the mine compared to his measurement

Velocity of photon is invariant on gravity. Out of that comes that photon clock will not have relativistic gravitational effect. I got that insight dhuring 4 days of za-zen meditation.
CALTECH has such a clock. I plan to have 4 clocks, 2 atom 2 photon and do experiment next year in South Africa in Gloden Mine Shaft 4200 m deep.
If someone is interested he can join us

HERE IS PAGE OF CALTECH PHOTON CLOCK
http://www.physorg.com/news5577.html
« Last Edit: 19/05/2010 19:28:27 by amrit »
 

Offline imatfaal

  • Neilep Level Member
  • ******
  • Posts: 2787
  • rouge moderator
    • View Profile

Velocity of photon is invariant on gravity. Out of that comes that photon clock will not have relativistic gravitational effect.

But the slowing of the photon clock is not premised on the concept that the speed of light has changed - quite the opposite, to the observer it is invariable.  it is time that is dilated - the passing of time has slowed.  If i have understood correctly it is not that the measuring-devices that display the passage of time are incorrect; but that the passing of time has slowed ie proper time is still displayed.

how big and expensive are these clocks?  I would have thought very...

Gonna go to caltech site now. thnks for link

Matthew
 

Offline imatfaal

  • Neilep Level Member
  • ******
  • Posts: 2787
  • rouge moderator
    • View Profile

HERE IS PAGE OF CALTECH PHOTON CLOCK
http://www.physorg.com/news5577.html

Amrit - Sorry to write consecutive posts but I think you might have put in a dud link. 

The link you gave and the paper that the physorg paper summarises is not for a photon clock that depends of the passage of light between two mirrors!!  It is a micromechanical device that is forced into oscillation by radiation-pressure; it is an analogue of a quartz clock that is forced into oscillation by electric current but using radiation-pressure.

I must admit that I thought and still kinda think that the photon clock based on a beam of light between two mirrors was an elegant gedanken to help elucidate SR.

Matthew
 

Offline amrit

  • Sr. Member
  • ****
  • Posts: 103
  • Power of science is uncompromised search for truth
    • View Profile
Matthew

you think it is possible to make a real Photon Clock with two mirrors ?
If yes, than we will do an interesting experiment.

yours amrit
 

Offline imatfaal

  • Neilep Level Member
  • ******
  • Posts: 2787
  • rouge moderator
    • View Profile
Matthew

you think it is possible to make a real Photon Clock with two mirrors ?
If yes, than we will do an interesting experiment.

yours amrit

Amrit - No I don't think it is possible , I think it is a Gedankenexperiment; ie a thought experiment to help people to get their heads around SR.  On top of that I think your concept that photon clock (if it existed) would be unaffected by gravitational potential time dilation is incorrect.  I must admit I have grave doubts about your initial statements; they challenge very profound and important ideas - and I do not think you have backed them up enough yet.

Matthew
 

Offline amrit

  • Sr. Member
  • ****
  • Posts: 103
  • Power of science is uncompromised search for truth
    • View Profile
Mathew is interesting link where Einstein discuss the subject:
http://www.relativitybook.com/resources/Einstein_gravity.html
important to know he never talks about fourth coordinate X4 as time,
he presented as X4 = ict.

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 ?

We all agree that c = 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.

yours amrit
« Last Edit: 21/05/2010 01:18:51 by amrit »
 

Offline JP

  • Neilep Level Member
  • ******
  • Posts: 3366
  • Thanked: 2 times
    • View Profile
He did that to make all the coordinates have the same units so that you can use (x1,x2,x3,x4) as a four-vector...
 

Offline amrit

  • Sr. Member
  • ****
  • Posts: 103
  • Power of science is uncompromised search for truth
    • View Profile
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.
 

Offline JP

  • Neilep Level Member
  • ******
  • Posts: 3366
  • Thanked: 2 times
    • View Profile
Gravity effects space and time.  This is why it can cause disagreement between your photon clocks at the center of the earth and in deep space.  Gravity doesn't have to effect the velocity of light in order to cause the clocks to disagree, since it effects the spatial distance between them.  Are you arguing that the clocks at the center of the earth and in deep space will agree perfectly when you compare them?
 

Offline graham.d

  • Neilep Level Member
  • ******
  • Posts: 2208
    • View Profile
A proper treatment should use GR but here is my reasoning; as I said before it is importent to understand what is meant by measuring times and lengths - you should really measure events and intervals as these would be invariant. Please bear with this lengthy description.

I prefer to use two observers - one at a long distance from the earth and another at the centre of the earth (ignoring practical difficulties that do not change the gedanken experiment). The reason is that neither will be in a gravitational field (or at least not one that cannot be made arbitrarily small) but the one at the earth's centre is at a lower gravitational potential.

The photon clock is constructed of two miirors spaced apart by a distance "x" so that a "tick" would be 2x/c long. In taking such a clock to the centre of the earth you, as a local observer, would not see any change in its behaviour. The mirrors will be the same distance apart however measured with any method you would have locally and the ticks would appear at the same time interval as when you constructed it (using measuring sticks, other clocks etc).

To a distant observer though, you and your clock have moved to a lower gravitational potential. The ticks from your clock (and any other clock) will be redshifted and running slow compared with his clocks. The apparent conundrum is why, if the velocity of light is the same to all observers, should the ticks from the photon clock be slow? The answer is (I think) that, at the lower potential, lengths (as measured by the distant observer) are larger so the mirrors are further apart. It is importent to understand how a distant observer would measure lengths and this is fundamental in solving even some apparent paradoxes in Special Relativity. The distant observer could measure the mirror spacing by sending a light pulse that partially reflects of the back of the first mirror (closest to him) but also passes by and reflects of the front face of the second mirror (furthest away from him). He would receive, some time later, two pulses with a time interval between them. This time interval (at the centre of the earth) would be the same as the tick time, but it would also be redshifted in returning to the distant observer. Like the tick, he would see that the gravitational potential gradient would have stretched the measured time to 2x'/c. This is interpreted exactly in the way that Lorentz contraction in SR is defined. It is the only way a distant observer can measure distances and lengths. The mirror spacing is larger to the distant observer.

The correct and more rigorous treatment would use GR and intervals in space-time but is mathematically challenging - at least for me.
« Last Edit: 21/05/2010 08:58:41 by graham.d »
 

Offline imatfaal

  • Neilep Level Member
  • ******
  • Posts: 2787
  • rouge moderator
    • View Profile
Amrit - I realise from your paper and other points you have made that you are trying to investigate new concepts of time - but in order to do this you are advancing arguments and quoting sources that explicitly require an engagement with the effet of gravity on space and time; and you seem to be avoiding this.  Your photon clocks will disagree for reasons that JP and Graham mentioned above.

With regards to your link of Einstein's notes - please read the final few paragraphs of section 3 and advise how this does not compromise your entire argument.  you will note that in the argument Einstein does not define 4th dimnsion attributes at all but talks of three-dimensional frames of reference in either uniform acceleration or homogeneous gravitational field.

in order to prove your points you must deal with observed and theoretical predicted time dilation and with spacial distortion (as described very clearly by Graham above) - which you have not done so far.

Matthew
 

Offline amrit

  • Sr. Member
  • ****
  • Posts: 103
  • Power of science is uncompromised search for truth
    • View Profile
Amrit - I realise from your paper and other points you have made that you are trying to investigate new concepts of time - but in order to do this you are advancing arguments and quoting sources that explicitly require an engagement with the effet of gravity on space and time; and you seem to be avoiding this.  Your photon clocks will disagree for reasons that JP and Graham mentioned above.

With regards to your link of Einstein's notes - please read the final few paragraphs of section 3 and advise how this does not compromise your entire argument.  you will note that in the argument Einstein does not define 4th dimnsion attributes at all but talks of three-dimensional frames of reference in either uniform acceleration or homogeneous gravitational field.

in order to prove your points you must deal with observed and theoretical predicted time dilation and with spacial distortion (as described very clearly by Graham above) - which you have not done so far.

Matthew

Matthew space is timeless.
With clocks we measure numeric order of material change i.e. motion running in space.
Fundamental unit of numeric order is Planck Time.
Velocity of atomic clocks depends on gravity.
Velocity of photon clocks is independent on gravity as C is constant.
This has nothing to do with close or distant observer.
Such are rules of the universe, we observe it or not.
http://www.vetrnica.net/index.php?option=com_content&view=article&id=21&Itemid=23
yours amrit
 

Offline amrit

  • Sr. Member
  • ****
  • Posts: 103
  • Power of science is uncompromised search for truth
    • View Profile
Gravity effects space and time.  This is why it can cause disagreement between your photon clocks at the center of the earth and in deep space.  Gravity doesn't have to effect the velocity of light in order to cause the clocks to disagree, since it effects the spatial distance between them.  Are you arguing that the clocks at the center of the earth and in deep space will agree perfectly when you compare them?

as C is invariant on inertial system and gravity, velocity of photon clocks is the same in the whole universe
velocity of atom clocks is not the same.....we know why and when
 

Offline graham.d

  • Neilep Level Member
  • ******
  • Posts: 2208
    • View Profile
Amrit, (to quote from Monty Python) this is contradiction, not argument.

"Space is timeless" is meaningless unless you explain your definitions
"'Velocity' of clocks" is also not what you mean (I think).
It has everything to do with the observer and the different gravitational potential. If you were to do the maths rigorously you would find the "spacetime interval" will be the same to all observers.
The rules of the universe are what they are and not what you choose them to be, so by all means do your experiment, but you seem to have presupposed the result. But if it turned out you were right you will surprise a lot of people :-)
 

Offline imatfaal

  • Neilep Level Member
  • ******
  • Posts: 2787
  • rouge moderator
    • View Profile
Amrit - I am afraid you are repeating assertions without providing anything more.  Would you care to explain how space can be timeless yet there is experimental and practical proof of time dilation through differing gravitational potential and relative velocity.  you keep on repeating that photon clocks are unvarying despite Graham's explanation under SR of why they vary - could you answer this single question.  

As an aside - I read your paper and flicked through the references; I was unable to find the quote you gave within the Eckle paper.  If, in fact, it was a paraphrase it should really not be in quotes - perhaps you could direct me towards it.
Matthew
 
 

Offline Farsight

  • Sr. Member
  • ****
  • Posts: 396
    • View Profile
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.
Hi amrit. I'm afraid this isn't right. The second clock runs slower than the first clock. People say the speed of light doesn't change, but it does. The reason why is simple: speed is distance over time. If we avoid radial length contraction by lying our clocks flat, the distance is the same for both clocks. However we say that time dilation has occurred for the second clock, and that the times are not the same. Speed equals distance over time, so if the distances are the same and the times aren't, the speeds aren't the same either, even though we measure them both to be 299,792,458 metres per second. There's a hidden scale-change at work here, wherein the clock goes slower not because "time goes slower", but because the light goes slower.
 

The Naked Scientists Forum


 

SMF 2.0.10 | SMF © 2015, Simple Machines
SMFAds for Free Forums