Personal Topic

[Moronium]

Yes, but velocity is not a satisfactory explanation of why moving clocks run slower AND clocks in a higher gravitational field run slower. Something more fundamental must link velocity time dilation with gravity time dilation.

 

Well, whatever the actual "cause," the correlation of clock retardation with increased speed is 100% and exactly in accordance with the predictions of the LT, so for predictive purposes it seems to be infallible.  There is no correlation with, for example, turning around during a journey. 

 

Just talking in Newtonian terms while ignoring GR, we never have had a satisfactory explanation for gravity, but, relying on Newton will get us to the moon and back.  We know the effect of gravity, even if we don't know the "true cause."  One would be ill-advised to start treating gravity as if it is always the result of the presence of water in a near-by lake, or something ridiculous like that.

Edited January 26, 2019 by Moronium

[Moronium]

 You can't even grasp the first concept that time dilation is not the same thing as age difference... I just learned last night that this has all been a made up story. The truth behind relativity is far more complex than they led us to believe...I'm not interested in discussing why that is or is not true.

 

Obviously.  Rave on.

[Moronium]

Yes, but velocity is not a satisfactory explanation of why moving clocks run slower AND clocks in a higher gravitational field run slower. Something more fundamental must link velocity time dilation with gravity time dilation.

 

Theoretically speaking, there is a very significant difference between time dilation in SR due to speed, and gravitational time dilation due to proximity to large masses in GR.

 

In GR the time dilation is absolute, not relative.  It is not a mere matter of perspective and the speed of light is not constant--it actually does vary with altitude. All observers will agree on this. I seem to recall that we discussed this difference at some length in another thread, Popeye.

 

So, if you're looking to connect the two, you would probably be much better off adopting a theory of motion which does not claim that time dilation is strictly relative and reciprocal.  There are such theories, and they have been experimentally confirmed, so why cling to SR? 

 

SR itself acknowledges that time dilation is not reciprocal, but is instead absolute and asymmetrical, in an accelerating frame, so the comcept is by no means foreign to SR.  This is also the reason why you can ONLY try to apply SR in inertial frames, not accelerating ones.  Accelerated motion is absolute, not relative.

 

Time dilation in Special relativity comes about because of both the relativity postulate (that motion can only be determined relative to some other object) along with the speed of light being a fundamental constant independent of source velocity. These two postulates are entirely symmetric in that the time dilation observed by objects in relative motion will be identical....

 

The important property regarding gravitational time dilation is that it is an absolute quantity (unlike relativistic time dilation). Thus it is possible to determine is one observer is in a gravitational field (or is undergoing acceleration).

 

If one twin goes on an interstellar journey travelling close to the speed of light, leaving the other at home, the travelling twin will return to meet a much older twin. Why does the travelling twin not age at the same rate? The resolution to this question resides in the fact that the travelling twin can be distinguished from the non-travelling twin. This requires an absolute effect...

 

 

https://www.quora.com/What-is-the-difference-between-relativistic-time-dilation-and-gravitational-time-dilation

 

That link is to a "physicist with 20 years experience," and I believe that some of the statements he makes there do not comport with accepted theory and experiment, but I think virtually all physicists agree with him about the absolute and relative character of time.dilation in GR vs SR.  It is also obvious (to me at least) that the resolution to the twin paradox basically undermines the claim that velocity-related time dilation is "relative" (i.e., reciprocal).

Edited January 26, 2019 by Moronium

[Moronium]

I said:

 

I believe that some of the statements he makes there do not comport with accepted theory and experiment...

 

 

 

The glib claim that there is "no paradox" in the twin scenario because the two twins are not in identical circumstances misconstrues the nature of the the alleged paradox.

 

If one twin had 10,000 freckles on his face and the other had 10,001 freckles, then their circumstances would not be identical, but so what?  How is that relevant?  What would that explain?  It is simply a distinction without a difference.

 

Tests in particle accelerating labs have conclusively shown that acceleration, per se, has NO effect on velocity-related time dilation.

 

The clock hypothesis is the assumption that the rate at which a clock is affected by time dilation does not depend on its acceleration but only on its instantaneous velocity....The clock hypothesis was implicitly (but not explicitly) included in Einstein's original 1905 formulation of special relativity. Since then, it has become a standard assumption and is usually included in the axioms of special relativity, especially in the light of experimental verification up to very high accelerations in particle accelerators.

 

 

https://en.wikipedia.org/wiki/Time_dilation#Clock_hypothesis

Edited January 26, 2019 by Moronium

[Moronium]

Tests in particle accelerating labs have conclusively shown that acceleration, per se, has NO effect on velocity-related time dilation.

 

 

That is one stumbling block which undercuts the simple reasoning that since acceleration is said to be equivalent to gravity, and since acceleration results in increased instantaneous speed in connection with velocity-induced time dilation, then gravity (or acceleration) must be the cause of the clock retardation which we see in connection with speed.

 

All the evidence we have acquired to date suggests that gravitational and speed effects on clock rates are completely independent phenomena.

Edited January 26, 2019 by Moronium

[Moronium]

The site I linked said:

 

If one twin goes on an interstellar journey travelling close to the speed of light, leaving the other at home, the travelling twin will return to meet a much older twin. Why does the travelling twin not age at the same rate? The resolution to this question resides in the fact that the travelling twin can be distinguished from the non-travelling twin. This requires an absolute effect...

 

 

So, to sum up what I'm trying to say in response, Popeye, let's see what this "absolute effect" is.

 

It's NOT acceleration.

 

It is, by all evidence, motion.  That is to say absolute motion, not relative motion.  Does this contradict the premises of SR?  Yes it does.  That's why the twin paradox is a paradox.  

 

The paradox is NOT that the two twins age differently.  That is indeed strange, and raises legitimate questions about "why" it happens, and what causes it. But it is not logically contradictory, nor is it in any way "paradoxical."

 

The paradox is that SR insists that you must accept all motion as being relative, but then comes up with an absolute answer in the twin paradox, i.e, an answer that cannot be obtained from relative motion.

 

The relevant distinction between the two twins is not that one accelerates and one doesn't.  It is that one has (absolutely) increased his speed, and one hasn't.

Edited January 26, 2019 by Moronium

[OceanBreeze]

The site I linked said:

 

 

So, to sum up what I'm trying to say in response, Popeye, let's see what this "absolute effect" is.

 

It's NOT acceleration.

 

It is, by all evidence, motion.  That is to say absolute motion, not relative motion.  Does this contradict the premises of SR?  Yes it does.  That's why the twin paradox is a paradox.  

 

The paradox is NOT that the two twins age differently.  That is indeed strange, and raises legitimate questions about "why" it happens, and what causes it. But it is not logically contradictory, nor is it in any way "paradoxical."

 

The paradox is that SR insists that you must accept all motion as being relative, but then comes up with an absolute answer in the twin paradox, i.e, an answer that cannot be obtained from relative motion.

 

The relevant distinction between the two twins is not that one accelerates and one doesn't.  It is that one has (absolutely) increased his speed, and one hasn't.

 

 

I have already said that the fundamental property at work here cannot be acceleration, so your are preaching to the choir, so to speak.

 

I still do not know what is fundamentally at work in time dilation (both velocity and gravity) but I am plodding my way through the math with the hope of gaining some insight, not that I think I am capable of solving this question!

 

I have come across this very interesting paper, that you and Ralf might enjoy reading. 

It hits on several things that I was thinking about, including conservation of mass and momentum and path length.

I won't try to summarize it here, please read it yourselves and then maybe we can discuss it.

[ralfcis]

I'm still on my last link. The problem is the physics stack exchange is not a forum. You only get a limited number of wishes before they grant you more wishes and the criteria is you can't ask questions that were already answered and you can't comment on answers given. Luckily they at least pointed me in the right direction, I could've been banned on my 1st question. So I'm going through a basic link on what is time dilation. I can now see how relativity defines time, how this article continually contradicts itself on that definition and how it considers the twin paradox as an example of time dilation but later says it isn't. The 3rd link in the series is much better. This introductory article is a mess and I can see why everyone is confused about the differences between time dilation and age difference.

 

Relativity's definition of time is just whack: it doesn't flow and it's the same thing as space. I'd like to say why I disagree with that on the physics stack exchange but would be banned immediately if I did. Yes time could be a dimensional line like any of the 3 dimensional lines of space and the universe is just a motionless block of ballistic gel with static world lines in it joining events. The common example in 2 dimensions is if time is the north direction and space is the east direction, the faster you want to go east, the slower you will go north.But they neglect to mention the car you're travelling in only has 1 speed and no brakes and that speed is c. And while you can travel east or west, you can't go south so there is a direction and speed of time, it isn't exactly like a space dimension. 

 

There are not 2 dimensions of space and one of time in the above example. If the world was flat, you would be jetting straight up at c if you were standing still relative to the earth. If you moved slightly, you'd be jetting up off the earth at  slight angle. This is what they neglected to mention.

[Moronium]

I have already said that the fundamental property at work here cannot be acceleration, so your are preaching to the choir, so to speak.

 

I still do not know what is fundamentally at work in time dilation (both velocity and gravity) but I am plodding my way through the math with the hope of gaining some insight, not that I think I am capable of solving this question!

 

I have come across this very interesting paper, that you and Ralf might enjoy reading. 

It hits on several things that I was thinking about, including conservation of mass and momentum and path length.

I won't try to summarize it here, please read it yourselves and then maybe we can discuss it.

 

1.  Sorry.  Although I know you were focusing on laws of mass/energy and momentum conservation (and of mass/energy equivalence), I somehow got the idea that you felt velocity dilation must be equivalent to gravitational dilation.  And since acceleration is supposedly equivalent to gravitation in GR, I got the impression that you might be thinking that acceleration (gravity) must be the cause of all time dilation.

 

2.  Another thing that threw me was your statement that you "do not believe in absolute motion."  In the other thread, I said that I thought you did in fact believe in absolute motion.  You have not made any further comments in that thread, so I'm not sure how to interpret your claim about absolute motion.  You do, however, seem to think that the LT is misguided in aligning velocity dilation with motion.

 

3.  I read the article you linked.  My criticisms of SR are essentially philosophical, not mathematical. My objections basically start with its fundamental assumptions that seem to me to reduce to the proposition that there is no objective reality and that only subjective perception is "real."  Put another way, my objections precede the math, and I don't look to the math formulas as a way of resolving questions of "reality."

Edited January 27, 2019 by Moronium

[Moronium]

This excerpt is from the article you cited, Popeye:

 

It is clear that observers in different frames can observe totally different things. For example, if you drop a ball from an airplane (neglecting the atmosphere), the ball will fall straight down relative to you. However a stationary observer on the ground will see the ball in a parabolic trajectory. However, it is far less clear that time should depend on the completion of a cycle. The issue is NOT that a shorter distance yields a shorter time, but rather that the time dilation is asymmetrical (different) depending on the path taken. In ESR time and space are supposed to be symmetrically interlinked. But it appears that dilated time is not symmetrical in these thought experiments

 

.

I certainly agree that time dilation is asymmetrical (not reciprocal), but, to be honest, I'm not quite sure what he is saying here.  I think I understand his conclusion, and why he reaches it, but what does he mean by "the completion of a cycle?"

Edited January 27, 2019 by Moronium

[Moronium]

Perhaps I'm getting too far off topic here, but I don't really think so.

 

It is clear that clocks tick at different rates when they are travelling at different speeds.  But does this mean that "time" itself varies?

 

According to Einstein (who at the time adopted a Machian positivism--which he later completely rejected), yes it does.  Time, he said, was merely what a clock measures.  He was basically giving what Percy Bridgeman later called an "operational definition" to time.

 

I disagree with the validity of this definition.  Time, as an abstract concept, does not change at all just because two clocks do not run at the same rate.  An easy to understand example is one where there are two watches and one runs slow.  After an hour is shown passing on one watch, the other may only register the passage of half an hour, for example.  Does this mean that the two durations are different, and that it all depends on the rate at which the clocks tick?  I don't see how any reasonable person can say "Yes, that's what it means."

 

Another example:  Suppose a powerful light beam is suddenly "turned on" and an observer 100 miles away sees it before one who is 200 miles away does.  Does this subjective difference in the time the light beam is "seen" by two different observers mean that the light was turned on at different times.  Does it mean that time is somehow "different" for the two observers?  I can't see how.  Yet this is the explicit basis which Einstein uses to explain his (dubious) concept of the "relativity of simultaneity."

Edited January 27, 2019 by Moronium

[Moronium]

Another excerpt from the article you cited, Popeye:

 

From this starting point, he [Einstein] goes on to derive the reciprocal observation equations for length and time where each observer says the other’s rod is shorter (length contraction), and each observer says the other’s clock is running slower (time dilation)....

 

ESR theory has been challenged in the interpretation of reciprocal observations of length and time; as well as whether other velocities can replace c in the equations of length contraction and time dilation. To my knowledge, actual experiments of this kind have not yet been conducted. Experiment must decide which view is correct. My paper raises the question: Is the physical interpretation of ESR completely correct? The meaning of Einstein’s postulate that physical laws are the same in all inertial frames is not clear when reciprocal observations seem contradictory....

 

we should question and experimentally test these very anti-intuitive aspects of ESR, even though they may be part and parcel of what we think are symmetries in nature. I think it is as important to test Reciprocal Observations as it has been to try to confirm the existence of Gravitational Waves. Symmetry breaking of reciprocal observations is almost as radical a concept as time dilation when Einstein surmised it in 1905....

 

It may not be that hard to test Reciprocal Times. Global Positioning Sattelite (GPS) clocks in accelerating satellites signal to earth. They could signal to each other to ascertain if each says the others’ time is slower.

 

 

1.  I believe that the issue of "reciprocal observations" has, in effect, already been tested. It is not a question of what clock on satellites "observe," (or, as this author puts it, what satellite clocks "say") but rather what they have been programmed to accept as being the case.  In the GPS, the satellite clocks presume that their clocks run slower, and that the clock at the ECI runs faster.  In other words, they assume that velocity related time dilation is NOT reciprocal.  This presumption makes the system work. 

 

2.  But I also think that the whole question of "reciprocal observations" is an irrelevant red herring, as far as physics (as opposed to perceptual psychology) is concerned to begin with.

 

In physics the ultimate issue is to ask what IS happening, and not just how some subject may "observe" it.  I will "think" the other guy's clock is moving more slowly than mine if  (1) I believe in the Lorentz transforms,  and (2) I posit that I am motionless, as SR requires me to do.  But what I think, based upon arbitrary and suspect assumptions, is not really the question here.  The question is whether his clock is, in actuality, moving slower than mine, NOT what I think or "say" (often erroneously called what I "observe") about it.

Edited January 27, 2019 by Moronium

[OceanBreeze]

 

3.  I read the article you linked.  My criticisms of SR are essentially philosophical, not mathematical. My objections basically start with its fundamental assumptions that seem to me to reduce to the proposition that there is no objective reality and that only subjective perception is "real."  Put another way, my objections precede the math, and I don't look to the math formulas as a way of resolving questions of "reality."

 

You read the entire paper already?

I am still going through it. I am a bit slow.

 

I have spent too many years learning and practicing engineering, and not much time on philosophy, so I am not equipped to answer that sort of question. I do think we are forced to work with the models because “reality” is very elusive and possibly unattainable. The mathematical models may seem to be complex but I strongly suspect the reality, whatever it may be, is far more complex than the models.

[OceanBreeze]

This excerpt is from the article you cited, Popeye:

 

.

I certainly agree that time dilation is asymmetrical (not reciprocal), but, to be honest, I'm not quite sure what he is saying here.  I think I understand his conclusion, and why he reaches it, but what does he mean by "the completion of a cycle?"

 

In the first three sentences he is just using the ball drop to make the obvious point that observers in different frames will observe it differently.

 

The last sentence “however, it is far less clear that time should depend on the completion of a cycle,” he is referring back to the previous discussion where he had a rod with a light pulse moving in different directions, and demonstrated that the time dilation was different in each direction and only the time dilation taken over the complete cycle matched the prediction of the Lorentz transform. In other words, he is saying that he demonstrated that reciprocal time dilation is asymmetrical. I am not 100% sure of that; it looks just a little too easy!

[OceanBreeze]

Another excerpt from the article you cited, Popeye:

 

 

1.  I believe that the issue of "reciprocal observations" has, in effect, already been tested. It is not a question of what clock on satellites "observe," (or, as this author puts it, what satellite clocks "say") but rather what they have been programmed to accept as being the case.  In the GPS, the satellite clocks presume that their clocks run slower, and that the clock at the ECI runs faster.  In other words, they assume that velocity related time dilation is NOT reciprocal.  This presumption makes the system work. 

 

2.  But I also think that the whole question of "reciprocal observations" is an irrelevant red herring, as far as physics (as opposed to perceptual psychology) is concerned to begin with.

 

In physics the ultimate issue is to ask what IS happening, and not just how some subject may "observe" it.  I will "think" the other guy's clock is moving more slowly than mine if  (1) I believe in the Lorentz transforms,  and (2) I posit that I am motionless, as SR requires me to do.  But what I think, based upon arbitrary and suspect assumptions, is not really the question here.  The question is whether his clock is, in actuality, moving slower than mine, NOT what I think or "say" (often erroneously called what I "observe") about it.

 

 

But that is what relativity is all about; how observers in different frames experience things like time, length and mass. Nobody has a lock on reality.

[Moronium]

I offer this as a historical but relevant sidenote:

 

I mentioned Percy Bridgeman a post or two back.  For those who are unfamiliar with him he wrote a book on the subject of the philosophy of science in 1927 called  "The Logic of Modern Physics"  which advocated operationalism and coined the term operational definition.

 

By the time this book was published, Einstein had already denounced the "positivistic" philosophy of science which Bridgeman's book promoted.  In an interview he said it fallaciously embodied Berkeley's solipsistic dictum that "to be is to be perceived."

 

As usual, Einstein was way ahead of his peers.  Percy's book, and similar thought, held sway as the dominant and commonly accepted philosophy of science until well after 1950.  It has since been thoroughly refuted and universally abandoned, but many of its remants still subsist in modern "scientific" thought.

Edited January 27, 2019 by Moronium

[Moronium]

” he is referring back to the previous discussion where he had a rod with a light pulse moving in different directions, and demonstrated that the time dilation was different in each direction and only the time dilation taken over the complete cycle matched the prediction of the Lorentz transform. 

 

OK, I see.  Thanks for that.