Experiments Supporting Relativity Theory

[BurtJordaan]

In a recent post, Viv Maxine asked about tests for relativistic time dilation that non-physicists can understand easily. The standard internet forum method is to simply refer people to the site http://math.ucr.edu/home/baez/physics/Relativity/SR/experiments.html. I think that most find that a bore to work through.

Here I want to point you to one of the latest and most beautifully simple relativity tests that I know of. There is a journalistic article on the experiment in Nature of September 2010, titled Relativity comes down to Earth. Written with typical journalistic flare and vague statements, like "warped time" and "time slows down for moving objects" (instead of "warped spacetime" and "clock rates slow down between relatively moving objects"), it is nevertheless a nice article, well worth a read.

TwinClocks

Essentially, it is two identical single-atom optical clocks, of which only was 'tickled' by a laser beam so that it oscillated with a average speed of only 10 meters per second, or 36 kilometers per hour. The clock's tick rate seemed to drop by one tick in around 10¹⁶ ticks, when compared to the other one. That's one tick in 10,000 trillion ticks, but since the clocks tick very, very fast, over a period of time, the 'tickled clock' recorded observably less elapsed time than the other one. Just like the 'away-twin' in the famous 'twin paradox' thought experiment.

The scientific report is available in Sciencemag.org of Nov 2010: Optical Clocks and Relativity. Although it does not offer an explanation for the 'twin paradox' resolution, it brings the experimental verification a little closer to home, so to speak...

[vivian maxine]

Thank you, Burt. Will you please remind me on what thread I posted my question? I want to see how I asked as this doesn't quite get what I was after. Perhaps I didn't word things rightly. Thanks.

[BurtJordaan]

Thank you, Burt. Will you please remind me on what thread I posted my question? I want to see how I asked as this doesn't quite get what I was after. Perhaps I didn't word things rightly. Thanks.

http://www.sciencechatforum.com/viewtopic.php?f=39&t=32714&p=320037#p320037

The slightly less "down-to-earth" test was the well-known Hafele–Keating experiment: https://en.wikipedia.org/wiki/Hafele%E2%80%93Keating_experiment.

[vivian maxine]

Good. I've been wandering all over the place. Be back. I don't think - well, I know - it isn't proof that one clock can be made to run more slowly that I was meaning to ask about. Shan't go into more now. Thank you.

[Inchworm]

Although it does not offer an explanation for the 'twin paradox' resolution, it brings the experimental verification a little closer to home, so to speak...

Hi Burt,

You probably say it doesn't solve the paradox because relativity isn't supposed to tell us which one of the clocks is moving, but the data from those two clocks does, so it kind of contradicts relativity. The Sagnac interferometer shows that light aimed in the direction of earth's rotation takes more time than the inverse, so maybe the slower clock was moving in that direction too, otherwise it should have run faster.

[BurtJordaan]

Hi Inch, have you read the details of the experiment? The one particle was jostled to and fro, the other one not. SR is crystal clear as to what it does to the elapsed time for each particle.

As you mentioned the Sagnac effect - did you know that Newton's theory cannot explain the full observed Sagnac effect, but SR can? But this will require a new thread if you want to discuss the details.

[vivian maxine]

Thank you, Burt. Will you please remind me on what thread I posted my question? I want to see how I asked as this doesn't quite get what I was after. Perhaps I didn't word things rightly. Thanks.

http://www.sciencechatforum.com/viewtopic.php?f=39&t=32714&p=320037#p320037

The slightly less "down-to-earth" test was the well-known Hafele–Keating experiment: https://en.wikipedia.org/wiki/Hafele%E2%80%93Keating_experiment.

All right. I did muddle the question. But that was what I wanted to know first before I moved on to the stories that go with it on relativity and they would be off-topic. Shall save those for another day. Thank you again.

[Inchworm]

Hi Inch, have you read the details of the experiment? The one particle was jostled to and fro, the other one not. SR is crystal clear as to what it does to the elapsed time for each particle.

Sr is about relative motion, so it certainly cannot be used to tell which one of the two clocks is moving, but since this experiment does, to me, it simply shows that SR has good chances to be wrong.

As you mentioned the Sagnac effect - did you know that Newton's theory cannot explain the full observed Sagnac effect, but SR can? But this will require a new thread if you want to discuss the details.

The Sagnac experiment only shows that the speed of light is absolute, that it doesn't depend on the motion of bodies in the relativity sense, but in the absolute sense. With it, we could measure the rotation of the universe for instance if it wasn't infinite. Rotation with regard to what? I'm afraid it is with regard to what we used to call the aether. A Sagnac interferometer would work the same if it was made out of air and sound for instance, providing the air would not be dragged by the device. To me, a propagating medium is by far the easiest way to understand the data.

[BurtJordaan]

Sr is about relative motion, so it certainly cannot be used to tell which one of the two clocks is moving, but since this experiment does, to me, it simply shows that SR has good chances to be wrong.

So you don't think there was relative motion between the two particles? Strange!
It may simply show that you have a 100% chance of being wrong... ;)

For the Sagnac effect, read the proper analysis at http://www.physicsinsights.org/sagnac_1.html.

But if you want to discuss that, we should start a new topic.

[Inchworm]

What I contest is not the idea that motion is relative, but that since it is, then an observer cannot know if it is him or the source of waves that is moving while only observing the waves. It is so for any kind of waves because doppler effect is symmetrical, but then it is contradictory to conclude that, in the case of clocks, we can tell which one is moving. If clocks are really affected by motion, and it seems that they are, we have to find another explanation than relative motion only, and the Sagnac effect is a good tool to work with. The author of the page on Sagnac at Physics Insight starts with saying that the effect is easy to explain with relativity, but at the second paragraph, he says that the effect is rather strange, and after having shown a drawing of the interferometer, he contradicts his introduction and says that the analysis is not obvious. To me, what is not obvious is using SR to explain the data, otherwise I find it quite simple to understand.

A Sagnac interferometer is simply able to measure the one way speed of light, and the other interferometers are not. If it had been possible to do that with a linear interferometer, Michelson would have detected the motion of the earth, and Einstein would have known that the motion of bodies was affecting the measured speed of light. This way, light would still take more time between the mirrors of its moving light clock than for the one of the observer at rest, but it wouldn't be because motion is relative otherwise it wouldn't be possible to tell which one is moving. Now, from that basis, we can ask ourselves the fatal question: would that clock run slow compared to the one at rest? My answer is no, because there would be no doppler effect to measure, and that the only way to measure time is to compare frequencies. For instance, on that basis, it certainly takes more time for the light from the sun to reach the earth because the solar system is really traveling through the galaxy, but that time is not affecting the timing of the orbital motion of the earth, which would always be one year whatever our speed through the galaxy.

To me, this analysis means that clocks cannot run slow whatever their speeds, and that we have to look for other explanations if data show the contrary.

[Inchworm]

Hi Burt,

I met a guy named David Cooper on another forum, and he succeeded to convince me that the length contraction of relativity was right. He did a very nice simulation of MM experiment using LET (Lorentz Aether Theory) as a basis for propagation of light.

My problem with relativity was that I did not understand the beaming phenomenon. In David's simulation, a laser is sending a photon at the future position of the upper mirror even if it is pointing at its actual position, and I couldn't understand why, so he simply told me to observe the way the photon was traveling in the laser while it was moving to the right, and I finally understood that only the photons already moving in the right direction in the laser could be reflected properly at its ends, in such a way that when they finally get out of it, they are actually traveling towards the interferometer's mirror. His simulation shows that only a contraction of the interferometer would permit the two photons to travel the same distance in the two arms, so this way, length contraction was easy to accept, but I still had a doubt on time dilation even if a photon would visibly travel more distance through aether between two moving atoms.

I said it would work if moving atoms were sending photons one at a time and if they would wait for the other atom to send it back, because then, the photons' frequency would be slower than with atoms at rest, but why would atoms do that I said, and he referred me to his Twin's paradox simulation this time. The solution of the paradox resides in the speed a ship has to get to catch up with another ship that has been traveling away from it for a while, and that is still traveling away at the moment the other ship tries to catch up with it. That ship will have to move so fast that, when they will meet, his clock will have slowed twice as much the clock from the other ship has. This way, wether we take the earth or the traveling twin as a reference frame, the result is the same: the twin that has to turn around if the earth is considered at rest stays younger. Have a look at his simulation for a better explanation. That's the first time I saw this paradox solved in a convincing way, so I began to believe Einstein was right about time dilation and length contraction, and I immediately tried to apply them to my small steps. (Feel free to send the rest of my post to Personal Theories if you feel that my conversion is not complete enough :0)

Atoms cannot emit photons without being accelerated or without absorbing an incoming one, so we can imagine that two atoms that are part of the same molecule could exchange indefinitely a photon that one of them would have emitted while it was accelerated, providing they could do so without loosing energy. As I said to David, I certainly cannot object to that mechanism since my small steps depend on it, but while looking at the distance my photon would travel back and forth, I realized that it would be different whether the atoms would be approaching or getting away from one another during their steps, and it has to be the same otherwise the steps wouldn't be the same.

So I juggled with the idea for a while until I realized that my steps necessarily had to suffer length contraction, and that any contraction due to motion had to happen at the beginning of any acceleration. If we accelerate a first atom which is part of a two atoms' molecule, it necessarily moves before the information from that acceleration has the time to reach the second atom, so the distance between them contracts, and if we are still accelerating that first atom while the information from the motion of the second atom is back, that information will simply pull the first atom forward a bit while it accelerates, so the distance between the two atoms will contract a bit more than previously, and it will go on contracting more and more until the acceleration ceases. At that moment, the information about the speed of the two atoms will be contained between them in the form of doppler effect: the rear atom will perceive redshift from the front one, which will pull it forward, and the front one will perceive blueshift from the rear one, which will push it forward. Contrary to my original small steps, during the motion of the molecule, the two time shifted motions of the atoms would thus happen at the same time, but those motions would still be due to the accumulated doppler effect between the two atoms. Here is the diagram and the explanations that I gave to David:

We have two atoms A and B that are part of the same molecule. The time interval represents the time the information takes between the two atoms at t0. I did not account for the time dilation of particle A since it moves before particle B, but I think we should. We accelerate A for a while and observe what happens to the system from t0 to t7. The blue arrows represent the blueshifted information that travels from A to B, and the red arrows represent the redshifted information that travels from B to A. The acceleration of A begins at t0 and ends at t4, so because of the time gap, the acceleration of B begins at t1 and ends at t5. After t5, the two atoms travel at the same speed, but we can easily see that the distance between them has contracted, and we can follow its progression during the acceleration. At that moment, the information on the future speed of each atom with regard to aether is situated between them in the form of doppler effect. The main idea is that, without doppler effect, there would be no motion between bonded particles, so there would be no motion either at our scale. I insist on the fact that we have to exert a force to introduce that doppler effect between them, and that this force represents mass. So with the same principle, we explain mass, motion and contraction. Of course motion is a bit more complicated this way, but we can discard the complicated Higgs, and we can study more closely what happens with motion at the micro scale, which could help us to link Relativity theory to Quantum theory.

Now what about time dilation? Can my small steps benefit from it? As David's simulation shows, a photon would take more time between my two atoms since they are moving, so the frequency at which this photon makes its roundtrip between them should be slowed, and that difference should show if we observe them while we are at rest, but what about the acceleration the first atom suffers before the other has moved? Would it add to the doppler effect? Soon to be released on your screens! :0)

[Inchworm]

Nobody seems to have noticed that the contraction becomes a lengthening when we pull on the right atom instead of pushing on the left one, what means that my idea might be wrong, but even if I'm wrong about that, David and me agree that acceleration still tells us which one of the twins travels, which also tells us which one is going to get younger, what contradicts the relativity principle. An interesting outcome of LET in this case is that the twin that accelerates can very well be getting older while moving away from the other twin because he might lose some speed with regard to ether while doing so, but as soon as he turns around and accelerates back towards his brother, he will have to travel twice as fast the same distance with regard to the same ether, so he will be the one to get younger anyway. I'm satisfied with that resolution of the twin's paradox, but it means that the relativity principle is wrong, so how about amending it? There is no motion without acceleration anyway, so there is no relative motion either. No more discussions on that paradox anymore, lots of bits saved! :0)

[ralfcis]

I'd love to see the math that backs up your claims because all I see is a jumble of popular science articles mashed up together in a giant word salad. I think more bits need be spent.

[Dave_Oblad]

Hi Ralfcis,

The issue with Relativity is that it is based on a Non-Linear Equation. Relativity only works on paper when absolutes are given. For example: Alice has an unknown inertial velocity greater than zero but less than 0.5c. Bob has an inertial velocity greater than Alice by 25%. What is the difference in their Clock Rates?

This question can not be answered.. as it has a full spectrum of answers dependent on Alice's Speed. Look at any Relativity problem. It will always have an absolute or an implied absolute. You can't determine clock dilation differentials between two velocities without an absolute because the Equation is non-linear.

So we have a paradox that:
1. Relativity Math doesn't work without an absolute.
2. Relativists demand that no absolutes can be known.

Strange set of affairs.. lol.

So I have no problem with Relativity.. it is correct. My beef stems from the amount of effort put into hiding the above paradox created by simultaneously supporting both statements 1 and 2 above that are contradictory.

Best wishes,
Dave :^)

[Sivad]

I've always been sort of baffled by the relativity of simultaneity, if there's no preferred reference frame then the arrow of time is kaput, no?

[ralfcis]

The issue with Relativity is that it is based on a Non-Linear Equation. Relativity only works on paper when absolutes are given.

I don't see the connection between these 2 statements. If you're talking about relativity is based on a pythagorean subtraction of squares instead of a sum of squares, I've normalized that in my latest SR defining the present post. Either way you see it, relativity was NEVER based on any absolutes, only relatives. That's the very first lesson of relativity and no matter how many times it's been explained to you, you just won't accept that. I've shown mathematically that no matter what stationary reference frame you orient the relative motion between two participants, everything works out the same. But you can't understand the algebra even though you're a "boolean mathematician" which is useless in this case.

The full spectrum of individual velocities is irrelevant to a relative velocity. The only reason you use this term is because YOU are assuming an absolute reference and can't understand what relative velocity means. I spent years in the same boat and only recently snapped out of it. The clock dilation values are always the same between the two participants in that full spectrum but they are not the same between the two participants and the absolute frame you have chosen. That last statement will mean nothing to you unless you dive into the algebra. You make wrong assumptions and instead of coming to the conclusion your assumptions are wrong, you instead assume relativity is wrong. I don't think you can be saved.

[Dave_Oblad]

Hi Ralfcis,

You know that the clock dilation factor is:
1.1547005383792517 for 0.5c
Correct?

You know that the clock dilation factor is:
2 for 0.8660254037844386c
Correct?

You know that the clock dilation factor is:
99 for 0.9999489834961278c
Correct?

The clock dilation factor is Not Linear. Thus you can not know the clock differential between two travelers if the only thing you know is.. how much faster one is to another.. PERIOD.

You can confirm this with a Relativity Calculator:
http://www.1728.org/reltivty.htm

Here is a Graph of Dilation Vs Velocity:

Notice the Graph is NOT Linear?

For any given velocity you are moving, Relative to Light Speed, you will have a very specific Clock Dilation factor. It doesn't matter how fast anything else is moving.. they have no effect on your personal dilation factor. Just your absolute velocity is all that's needed to compute your exact Dilation Factor.

Given two parties at non-equal velocities, the Clock Dilation is a non-linear Differential as a function of knowing both their velocities Relative to Light Speed.

Or.. knowing the absolute velocity of one and knowing the other is an absolute relative velocity to the first.

Only knowing the difference between their velocities is completely worthless information because the Dilation Function is NOT Linear.

Want more proof? Ok.. Alice is traveling at velocity X.. while Bob is traveling in the same direction as Alice but 0.25c faster. How much slower is Bob's clock than Alice's clock?

Use the Graph.. Put Alice at any Velocity and you will see that Bob's clock dilation is a non linear function of Alice's velocity. So even if you know their relative velocity to each other (0.25c), you can't know the differential clock dilation between them. PERIOD!

This problem has an infinite number of answers until one locks down Alice's Absolute Speed. Your favorite problem where party (A) is at 0.6c and party (B) is at 0.8c is only solvable because you have applied those absolute velocities. But the problem is not solvable.. if all you know is that their relative velocity difference is 0.2c.

That should be pretty obvious to anybody.. that looks at the Math.

Regards,
Dave :^)

[ralfcis]

Dave, you don't know the meaning of relative velocity . . Period!

1st relative velocity is not relative to the speed of light because that would make it the speed of light.

2nd You're listing all these velocities as individual absolute velocities that are not relative to anything except, wrongly, to the speed of light.

3rd you forgot to mention your consortium of future scientists who will prove relative velocity is relative to the CMB rather than between 2 participants.

4th you keep confusing fractions and factors as relative to the speed of light because it includes a fraction and c. That's not relative velocity.

[Dave_Oblad]

Hi Ralfcis,

Relative velocity is the velocity of an object or observer B in the rest frame of another object or observer A.

This doesn't change the facts as I stated above, as long as the Two-Way Speed of Light is an absolute constant.

Regards,
Dave :^)

[ralfcis]

Dave just answer me one question as honestly as you can. Which is the absolute velocity and which is the relative velocity: .66667c or 2x10⁸m/s?

[Dave_Oblad]

Hi Ralfcis,

0.66667c is 199,862,638 Meters per Second. (approximate)
2x10⁸ m/s is 200,000,000 Meters per Second.

Both are just velocities as Distance in Meters by Time in Seconds.

Personally, I would say the 0.66667c is Relative to Light Speed (reason for the (c) being placed). In my book, that would be an Absolute Velocity as c is a constant and thus is a specific fraction of an absolute maximum (well defined) anchor velocity.

The other Velocity doesn't define what it is Relative to. It's too ambiguous. It doesn't have an anchor as stated. Thus it would seem to be solely a Relative Velocity.

My best guess... cheers.

Regards,
Dave :^)

Ps. Have to go to bed now.. later.. Good Night :)

[Inchworm]

I'd love to see the math that backs up your claims because all I see is a jumble of popular science articles mashed up together in a giant word salad. I think more bits need be spent.

If you didn't do it yet, take a look at those simulations, they use SR maths to show that LET gives the same result.
http://www.magicschoolbook.com/science/relativity.html

[Inchworm]

I'd love to see the math that backs up your claims because all I see is a jumble of popular science articles mashed up together in a giant word salad. I think more bits need be spent.

If you didn't do it yet, take a look at those simulations, they use SR maths to show that LET gives the same result, but with a better logic. It's not maths that add some logic, it's ether.
http://www.magicschoolbook.com/science/relativity.html

[ralfcis]

Dave,
Guessing the right answer is not the same as knowing the right answer. In this case, that was not done but that temporary pain you must have felt second guessing yourself; that is called thinking.

[Dave_Oblad]

Hi Ralfcis,

It was a deductive guess. BTW, I meant to address my first post here to Inchworm not you.. I'm sorry. Actually, I should have addressed it to Jorrie as this is his thread.

The following is addressed to anyone that can give a straight answer:

I have a burning question in mind and was going to solve it on my own.. when I have the time.

Suppose I created a Relativity Calculator using absolutes only.
I use an absolute velocity for Alice and compute her dilation factor.
I use an absolute velocity for Bob and compute his dilation factor.
Then I calculate the real dilation differential (ratio).
Save that Answer.

Next.. I do the same.. but I treat Alice as a variable unknown speed.. but I compute her absolute dilation anyway, it's just she doesn't know how fast she is moving. Then I treat Her clock as absolute (zero velocity) and only give her Bob's Velocity relative to Hers. So, using her (slowed clock) and only her knowing how much faster Bob is moving, I calculate the dilation differential ratio as expected from her point of view.
Save that answer.

I then compare both ratio answers derived from above two methods.

Will the dilation ratio for both methods above produce the same correct answer for all possible velocities applied to Alice?

Intuition says it won't.. but I have yet had the time to try this myself.

Regards,
Dave :^)

[Inchworm]

The issue with Relativity is that it is based on a Non-Linear Equation. Relativity only works on paper when absolutes are given. For example: Alice has an unknown inertial velocity greater than zero but less than 0.5c. Bob has an inertial velocity greater than Alice by 25%. What is the difference in their Clock Rates?

This question can not be answered.. as it has a full spectrum of answers dependent on Alice's Speed. Look at any Relativity problem. It will always have an absolute or an implied absolute. You can't determine clock dilation differentials between two velocities without an absolute because the Equation is non-linear.

So we have a paradox that:
1. Relativity Math doesn't work without an absolute.
2. Relativists demand that no absolutes can be known.

Strange set of affairs.. lol.

So I have no problem with Relativity.. it is correct. My beef stems from the amount of effort put into hiding the above paradox created by simultaneously supporting both statements 1 and 2 above that are contradictory.

Best wishes,
Dave :^)

Hi Dave! You said your answer was addressed to me, so here I am! :0)

Based on my new conversion, my answer is that relativists cannot compute any time dilation unless they know which individual is moving faster with regard to aether, or unless they know which one has accelerated in the case of the twins. The real paradox is thus about why they do not change their mind about motion being relative, and the answer is: because they know they are going to get kicked out of their beloved forum manu militari. :0)

[ralfcis]

Birds of a feather.

[Inchworm]

Birds of a RR feather, or birds of a LET feather, they both flock together anyway! :0)

[BurtJordaan]

Based on my new conversion, my answer is that relativists cannot compute any time dilation unless they know which individual is moving faster with regard to aether, or unless they know which one has accelerated in the case of the twins.

It sounds like you have been converted to LET. Not too bad a step along the way to be finally converted to the truth! ;) The fact that LET has no clue which frame is the aether and just picks a convenient one, should guide you to the truth.

In SR (as in LET) there is only relative time dilation and all inertial frames can be treated as equal. So to talk about which frame "is dilated" is just meaningless.

[Inchworm]

You're right Burt, both theories give the same predictions, but only one of them succeeded to convince me, and it is because we can make a simulation of the MM experiment with LET and not with SR. Moreover, this simulation helped me to understand the beaming phenomenon, because we can see the photon following the telescope tube while it is moving through aether, which meant to me that only the photons emitted in that direction can be amplified by the laser system, so they already have the right direction to hit the mirrors of the interferometer when they leave the telescope.

With LET, we can know which frame is dilated only if we know which body has accelerated, and if we know where and when the acceleration started with regard to the observer. For instance, if the observer is at rest beside the body and the body accelerates away from him, then we know it is the body that dilates. If the body stops and accelerates back to the observer, then we know it is still the body that dilates. That reasoning explains the twins' paradox a lot more easily than the other explanations I saw. It also explains all the data we have from relativistic speeds, like the Muon or the particles in accelerators for instance. If you know any data for which that principle doesn't apply, tell me, who knows if I won't start believing in god soon, so I might still change my mind again for SR! :0)