Three Experiments Challenging SRT

[Read-Only]

What confounds me about people that don't understand relativity is the fact that they fail to grasp the fact that it's all about RELATIVE things! It compares in NO WAY to what people think about "ordinary" conditions - Euclidean geometry and Newtonian physics. They cannot unwrap their heads from "ordinary" everyday experience long enough to see how relativity works.

If they could, all the difficulties about clocks would immediately vanish. The very FIRST thing they should put some effort into understanding is frames of reference and it's actually not that hard to learn. But they try to get ahead of the learning process and thus become lost before they really ever start.

There's no mystery at all as to which of a set of clocks runs slower than the other. That can be understood without having to refer to math at all.

Here's a clear and simple way to do that: Two clocks sitting side by side will show no difference in time. However, if one is accelerated - in reference to the other - it will tick more slowly. How do we know is isn't the first one that runs slower? Simple - which of the two actually underwent acceleration? That's THE one that will always be running slower. So one more time... What happened to the first clock? Answer: nothing - and it remains unchanged. What happened to the second clock? Answer: It underwent acceleration and did NOT remain unchanged as a result! So it, and only it, now runs slower.

 

[Neverfly]

What confounds me about people that don't understand relativity is the fact that they fail to grasp the fact that it's all about RELATIVE things! It compares in NO WAY to what people think about "ordinary" conditions - Euclidean geometry and Newtonian physics. They cannot unwrap their heads from "ordinary" everyday experience long enough to see how relativity works.

If they could, all the difficulties about clocks would immediately vanish. The very FIRST thing they should put some effort into understanding is frames of reference and it's actually not that hard to learn. But they try to get ahead of the learning process and thus become lost before they really ever start.

There's no mystery at all as to which of a set of clocks runs slower than the other. That can be understood without having to refer to math at all.

Here's a clear and simple way to do that: Two clocks sitting side by side will show no difference in time. However, if one is accelerated - in reference to the other - it will tick more slowly. How do we know is isn't the first one that runs slower? Simple - which of the two actually underwent acceleration? That's THE one that will always be running slower. So one more time... What happened to the first clock? Answer: nothing - and it remains unchanged. What happened to the second clock? Answer: It underwent acceleration and did NOT remain unchanged as a result! So it, and only it, now runs slower.

Lakon had asked what the mechanism was that created the effect. And that's less easy for a mind accustomed to certain Newtonian Mechanics to wrap around, considering how 'time' must be viewed to make it work.
You see, the description appears to alter reality as we know it- that if light is a constant and it must travel a greater distance for a moving object than it would for an object at rest, that it somehow alters time seems very odd. Why would light bend the physics of the universe to its will?
It's not about that, however. It's about the nature of space-time, not just time, and how matter effects space-time and how it affects space-time when it moves in relation to other matter. How it moves in relation to a constant. If time is something that matter moves through rather than time being something that passes by at a constant rate, it makes more sense. Time is not a constant. Time is a perception, an effect, created by the motion of matter, not by the motion of time.
So, there isn't a mechanism, there is a consistency. As all of physics, conservation.

 

[Lakon]

Relativity doesn't make any such demand. So Dingle didn't do his homework and if you think that's fascinating neither did you.

Thanks for your response. Just a quick one for the moment, due to time constraints.

In my earlier post I was of course, talking only about SRT. From the Dingle quote;

Two exactly similar clocks, A and B, are in uniform relative motion.
Einstein's special relativity theory requires
(1) that the motion is wholly relative,
i.e. it belongs no more to one dock than to the other;
(2) that the clocks work at
different rates, i.e. one works faster than the other.

Are you saying this is not accurate ? If so, please elaborate.

 

[Tach]

(Underlined) Tach, length contraction has to me, seemed to be another thing that is quite weird and difficult to get my mind around.

What is the physical mechanism that causes a physical object to actually contract ? I simply don't know and can't imagine.

Imagine a cylindrical spaceship moving away from an observer, A, in a collinear path, at a speed such that it's length is contracted by half - say from 100 metres to 50 metres, according to observer A.

Questions;
- Say the spaceship was 10 metres in diameter. Would it's diameter also contract by half ?

1. Nope, I just explained that there is no contraction in the direction(s) perpendicular to motion.

- Is it's length contraction a real, physical contraction or just a visual thing, i.e., in the eyes of the observer A?

2. It is real.

- If it is a real physical thing what length would the spaceship appear to a second observer, B, if B saw it rush past him and his line of sight was perpendicular to it's line of travel ?

3. The simple answer is that the effect does not depend on the "line of sight" it depends only on the direction of relative motion. A much more complicated answer is that , once you start bringing in the physiology of sight, you need to take into consideration some very complicated effects of relativity of simultaneity (google "the Terrell-Penrose effect").

 

[Tach]

I continue to try to get a better understanding about time dilation. I have read a good deal both for and against - such as might be available in my language, Modern English, which is a rich and powerful language and hasn't failed me yet in any other field of endeavour.

And yes, I've come across Dingle. I recall reference to him in posts long ago in this thread, but never took much notice, particularly because such posts were heavy with mathematics (a language I don't speak), so I skipped them altogether.

If I can summarise my present conceptions, I can say that the pro time dilation camp rests on, mainly, assuming that one twin is somewhat fixed or at rest, while the other twin is the one doing the travelling.

The anti time dilation camp, however .. well .. I don't think I could ever express it better than Dingle has, in a book styled;


Can anyone proffer an answer to Dingle here ?

I will of course, continue to read this fascinating book, and see where it goes.

The Lorentz transformation for time is:

$$t' = \gamma (t-vx/c^2)$$.

This equation implies :
$$t' = \gamma t$$ at $$x = 0$$.
Its algebraic inverse is:

$$t = \gamma (t'+vx'/c^2)$$.

This equation implies $$t = \gamma t'$$ at $$x' = 0$$.
Dingle alleged that these two facts are mutually contradictory, because the first implies $$t'/t = \gamma$$ and the second implies $$t/t' = \gamma$$. However, these ratios apply to two different conditions, namely, $$x = 0$$ and $$x' = 0$$ respectively. Hence, contrary to Dingle's assertion, there is no contradiction, nor are these relations merely "appearances". They are the actual ratios of the inertial time coordinates along two different directions in space-time. In order to for you to understand relativity, you will need to learn the underlying math.

 

[Tach]

Thanks for your response. Just a quick one for the moment, due to time constraints.

In my earlier post I was of course, talking only about SRT. From the Dingle quote;

Two exactly similar clocks, A and B, are in uniform relative motion.
Einstein's special relativity theory requires
(1) that the motion is wholly relative,
i.e. it belongs no more to one dock than to the other;
(2) that the clocks work at
different rates, i.e. one works faster than the other.

Are you saying this is not accurate ? If so, please elaborate.

Not accurate, see the post above. You can stop wasting your time reading the Dingle "book". It is a waste of time (you already wasted your money buying it).

 

[OnlyMe]

Thanks for your response. Just a quick one for the moment, due to time constraints.

In my earlier post I was of course, talking only about SRT. From the Dingle quote;

Two exactly similar clocks, A and B, are in uniform relative motion.
Einstein's special relativity theory requires
(1) that the motion is wholly relative,
i.e. it belongs no more to one dock than to the other;
(2) that the clocks work at
different rates, i.e. one works faster than the other.

Are you saying this is not accurate ? If so, please elaborate.

Lakon, taking Dingle's hypothetical literarily, is an example of one part of what SRT presented and one component of what leads to the Twin Paradox. With no other information aside from their relative velocity no two inertial observers can say who is moving relative to who. All inertial frames of reference are equivalent and the laws of physics applies equally to all inertial frames of reference.

And it is true that within the context of SRT, that even for the twin we say is at rest, we can never be certain there is no motion.., that even the twin at rest in the hypothetical is not experiencing some velocity. It is in fact according to SRT safe to assume that all clocks do have some velocity. That no inertial frame of reference is truely at rest... Dingle then says that because we cannot know which is moving relative to the other, how can we know which is experiencing time dilation? Especially when not knowing who is moving, both would see the other as time dilated, relative to theirself.

But there is a difference that has been omitted in the reference you cite. Other posters have repeatedly introduced it as the deciding factor. The two clocks or twins begin in a common frame of reference and one then accelerates, in the process changing inertial frames and adding some velocity to any velocity the two may have shared, when they were side by side and the clocks were synchronized. Even where you assume that both clocks began with some constant velocity, the clock that was accelerated then experiences some velocity in addition, to that common beginning frame of reference.

Generally in the twin paradox, it is assumed that the two are at rest.., relative to the conditions of the hypothetical. But as long as you are talking about conditions consistent with SRT and the abscence of gravity.., and are including one clock that begins and ends in the common frame of reference it does not matter, if they are really at rest or just moving together at the start and end.

The clock which is moved relative to the common frame of reference is the clock that will be time dilated relative to that common frame of reference... And it is acceleration that separates the two clocks and tells you which one had some additional velocity, relative to their common beginning and ending, frame of reference.

 

[Janus58]

Thanks for your response. Just a quick one for the moment, due to time constraints.

In my earlier post I was of course, talking only about SRT. From the Dingle quote;

Two exactly similar clocks, A and B, are in uniform relative motion.
Einstein's special relativity theory requires
(1) that the motion is wholly relative,
i.e. it belongs no more to one dock than to the other;
(2) that the clocks work at
different rates, i.e. one works faster than the other.

Are you saying this is not accurate ? If so, please elaborate.

The second statement is inaccurate in that it implies an absoluteness to the clock rates. I can find a third frame in which the clocks run at the same rate.

Let's see if I can explain where Dingle goes wrong by way of analogy. In it, we'll treat the passage of time like it is like traveling a distance.

Dingle treats time as if it it runs in a North-South direction. By this analogy if we say the clocks run at as different rates, they are traveling from South to North at different rates. It is easy to see in this example if you have 2 "clocks" you can't have both clocks being further North than the other. This is the "contradiction" he claims happens with relativity.

However, this is not how time behaves in Relativity. In Relativity, time behaves as if if it runs in the back to front direction. Unlike North and South, which remains fixed no matter what direction you face. Front and back turns "with you" as you turn.

So for example, if you have two men, A&B walking along side of each other in the same direction they travel through time at the same rate. Now assume that B turns and starts walking in a slightly different direction without changing his gait. After a while, he will note that A has fallen behind him (instead of being abreast with him, he has to look back over his shoulder to see A). Sine he judges progress through time as distance traveled in the direction he is facing, Man A is making less progress in time (His clock runs slower.).

However, if we now switch to Man A, we find he will note that it is B that is making less progress (As A judges progress as being in the direction he is facing.) Thus both men judge that other as making less progress then themselves, and since there is no absolute "direction" by which to judge progress, both are equally correct.

So this is where Dingle goes wrong: He uses rules from one game to analyze another and complains that the results don't make sense.

 

[Tach]

Lakon, taking Dingle's hypothetical literarily, is an example of one part of what SRT presented and one component of what leads to the Twin Paradox. With no other information aside from their relative velocity no two inertial observers can say who is moving relative to who. All inertial frames of reference are equivalent and the laws of physics applies equally to all inertial frames of reference.

You are persisting in your error of co-mingling time dilation and the Twins Paradox. They are two different effects. Lakon is talking about time dilation, more precisely about Dingle's misconceptions about SR time dilation. Nothing to do with the Twins Paradox.

 

[OnlyMe]

Lakon, taking Dingle's hypothetical literarily, is an example of one part of what SRT presented and one component of what leads to the Twin Paradox. With no other information aside from their relative velocity no two inertial observers can say who is moving relative to who. All inertial frames of reference are equivalent and the laws of physics applies equally to all inertial frames of reference.

You are persisting in your error of co-mingling time dilation and the Twins Paradox. They are two different effects. Lakon is talking about time dilation, more precisely about Dingle's misconceptions about SR time dilation. Nothing to do with the Twins Paradox.

Tach, this discussion and Lakon's questions about time dilation have not been limited to the just recent reference to Dingle. See his post below... (quoted only in part)

One problem I'm having is who decided who is travelling and who is at rest. If the travelling twin returned to earth he would actually be younger because he was travelling and earthbound one was at rest, right ?

But doesn't this fly in the face of relatiivity itself ? Who decided who is at rest ? Between the two of them, there's only their relative motion, right ?....

I am not confused or unnecessarily commingling, anything. The twin paradox does involve time dilation and sometimes confusion, can be addressed within the context of the Relativity of Simultaneity.

The objective is to speak to the question presented, in a manner consistent with the questioner's understanding. Which within this discussion has not been limited to a single current reference.

What ever things look like to you, Lakon does appear to be trying to understand the issue raised. Even to the extent of seeking out references, like Dingle, independent of the discussion, or references others have offered. And several times over the course of the discussion various posters have attempted explanations approaching the question from different angles.

If someone does not at first understand, it is better to try another approach, than to criticize. Not all of those approaches and attempted explanations will be without some error of semantics or even be consistent with traditional solutions. The fact that you are unable to address the question(s) without the math, which Lakon has already said is of no help, does not mean that others should not try.

And just so you don't waste time, I am not going to get into a side debate with you here.., and I really don't care much what you think or believe. You are a fair hand at the math, but not really much good at general communication.

 

[Tach]

The twin paradox does involve time dilation and sometimes confusion, can be addressed within the context of the Relativity of Simultaneity.

You can't tell the difference between elapsed proper time and time dilation. Understanding the difference requires a little math, since you can't understand the math, the discussion tends to repeat itself.

 

[Lakon]

While the theories discussed here do not even begin to address the mechanism, they only describe the experience and observations that lead to that conclusion, I'll give you the short answer as I see it — inertia. But then the detail of how that is, lies again not in the theories discussed here, rather they will be found within the context of QM.



As mentioned above the physical mechanism is inertia. But understanding that time dilation does occur does not require an understanding of how inertia emerges.., to be the mechanism. It is a fact that clocks in motion run at a slower rate than clocks at rest. Tested and proven true. Clocks are the rulers we use to measure time, so if the ruler you are using is running slower when you are moving than it was when you were at rest, you are experiencing time dilation and will age slower, than you would have, had you remained at rest. (all mentions of at rest are naturally intended to be assumed as at relative rest)

However, you must keep in mind that no one has proven what the mechanism is or how it works, beyond a variety of theoretical explorations. Both SR and GR do no better than to describe and predict, what we do and will observe and experience. Neither one, says how or why, things are the way they are.

One further note, you do not need to have a masters in mathematics to understand SR. It is a great help where GR is concerned. Understanding the math just makes grasping the conceptual model(s) and discussing and describing them easier.

Hi OnlyMe

Thats rather extraordinary. I've never heard it put that way before - that the physical mechanism that causes time dilation is ..

Inertia; (thefreedictionary.com)
1. Physics The tendency of a body to resist acceleration; the tendency of a body at rest to remain at rest or of a body in straight line motion to stay in motion in a straight line unless acted on by an outside force

.. and that the details can (only ?) be found in Quantum Mechanics. This moves it further into the realm of the mysterious so far as I'm concerned, particularly as you then say that no one has proven what the mechanism is or how it works.

I'm having much headache with relativity at the moment, so I'll have to leave QM for another time, unless of cource, you can elucidate a little.

 

[Lakon]

Relativity doesn't make any such demand. So Dingle didn't do his homework and if you think that's fascinating neither did you.

In the Dingle quote, he is talking about SRT only. Which of his content do you feel was not consistent with SRT ?

Yes, I haven't done my homework. But I hardly think you can say that of Dingle. Even his opponents of that era respected his 50 year focus on relativity.

 

[Lakon]

What confounds me about people that don't understand relativity is the fact that they fail to grasp the fact that it's all about RELATIVE things! It compares in NO WAY to what people think about "ordinary" conditions - Euclidean geometry and Newtonian physics. They cannot unwrap their heads from "ordinary" everyday experience long enough to see how relativity works.

If they could, all the difficulties about clocks would immediately vanish. The very FIRST thing they should put some effort into understanding is frames of reference and it's actually not that hard to learn. But they try to get ahead of the learning process and thus become lost before they really ever start.

There's no mystery at all as to which of a set of clocks runs slower than the other. That can be understood without having to refer to math at all.

Here's a clear and simple way to do that: Two clocks sitting side by side will show no difference in time. However, if one is accelerated - in reference to the other - it will tick more slowly. How do we know is isn't the first one that runs slower? Simple - which of the two actually underwent acceleration? That's THE one that will always be running slower. So one more time... What happened to the first clock? Answer: nothing - and it remains unchanged. What happened to the second clock? Answer: It underwent acceleration and did NOT remain unchanged as a result! So it, and only it, now runs slower.

I thought SRT involved only inertia (constant speed) and not acceleration. It is SRT that I'm querying.

 

[Lakon]

1. Nope, I just explained that there is no contraction in the direction(s) perpendicular to motion.

2. It is real.

3. The simple answer is that the effect does not depend on the "line of sight" it depends only on the direction of relative motion. A much more complicated answer is that , once you start bringing in the physiology of sight, you need to take into consideration some very complicated effects of relativity of simultaneity (google "the Terrell-Penrose effect").

OK, it's a real, physical contraction. Bear with my ignorance, but upon returning to earth, would it remain contracted ?

And if so, it doesn't bode well for future interstellar space travel, does it ? I had hopes for the prospect, say in 500, or 1,000 years or so. You might laugh, but we have gone from horse and carriage to International Space Station in merely 160 years or so.

So, we'd have our travellers coming back - or even just getting there, dwarfed down significantly, or even pancaked, depending on their hibernation pods attitude to their line of travel .. could even become 2 dimensional if they travelled far enough

I googled the T-P effect as you suggested, and from Wiki, got ..

Terrell's paper pointed out that although special relativity appeared to describe an "observed contraction" in moving objects, these interpreted "observations" were not to be confused with the theory's literal predictions for the visible appearance of a moving object. Thanks to the differential timelag effects in signals reaching the observer from the object's different parts, a receding object would appear contracted, an approaching object would appear elongated (even under special relativity) and the geometry of a passing object would appear skewed, as if rotated.

Appear .. appear .. observed .. appeared .. appeared ..

More stuff to get my mind around, I suppose. I'll put it on the list.

 

[Lakon]

Lakon, taking Dingle's hypothetical literarily, is an example of one part of what SRT presented and one component of what leads to the Twin Paradox. With no other information aside from their relative velocity no two inertial observers can say who is moving relative to who. All inertial frames of reference are equivalent and the laws of physics applies equally to all inertial frames of reference.

And it is true that within the context of SRT, that even for the twin we say is at rest, we can never be certain there is no motion.., that even the twin at rest in the hypothetical is not experiencing some velocity. It is in fact according to SRT safe to assume that all clocks do have some velocity. That no inertial frame of reference is truely at rest... Dingle then says that because we cannot know which is moving relative to the other, how can we know which is experiencing time dilation? Especially when not knowing who is moving, both would see the other as time dilated, relative to theirself.

But there is a difference that has been omitted in the reference you cite. Other posters have repeatedly introduced it as the deciding factor. The two clocks or twins begin in a common frame of reference and one then accelerates, in the process changing inertial frames and adding some velocity to any velocity the two may have shared, when they were side by side and the clocks were synchronized. Even where you assume that both clocks began with some constant velocity, the clock that was accelerated then experiences some velocity in addition, to that common beginning frame of reference.

Generally in the twin paradox, it is assumed that the two are at rest.., relative to the conditions of the hypothetical. But as long as you are talking about conditions consistent with SRT and the abscence of gravity.., and are including one clock that begins and ends in the common frame of reference it does not matter, if they are really at rest or just moving together at the start and end.

The clock which is moved relative to the common frame of reference is the clock that will be time dilated relative to that common frame of reference... And it is acceleration that separates the two clocks and tells you which one had some additional velocity, relative to their common beginning and ending, frame of reference.

I hope by now, I have clarified that my more recent enquiries were concerning SRT which involves uniform relative motion.

I really do admire and appreciate the time and effort you put into explaining things and meeting people (well, me on this occasion) at their level.

 

[Lakon]

The second statement is inaccurate in that it implies an absoluteness to the clock rates. I can find a third frame in which the clocks run at the same rate.

Let's see if I can explain where Dingle goes wrong by way of analogy. In it, we'll treat the passage of time like it is like traveling a distance.

Dingle treats time as if it it runs in a North-South direction. By this analogy if we say the clocks run at as different rates, they are traveling from South to North at different rates. It is easy to see in this example if you have 2 "clocks" you can't have both clocks being further North than the other. This is the "contradiction" he claims happens with relativity.

However, this is not how time behaves in Relativity. In Relativity, time behaves as if if it runs in the back to front direction. Unlike North and South, which remains fixed no matter what direction you face. Front and back turns "with you" as you turn.

So for example, if you have two men, A&B walking along side of each other in the same direction they travel through time at the same rate. Now assume that B turns and starts walking in a slightly different direction without changing his gait. After a while, he will note that A has fallen behind him (instead of being abreast with him, he has to look back over his shoulder to see A). Sine he judges progress through time as distance traveled in the direction he is facing, Man A is making less progress in time (His clock runs slower.).

However, if we now switch to Man A, we find he will note that it is B that is making less progress (As A judges progress as being in the direction he is facing.) Thus both men judge that other as making less progress then themselves, and since there is no absolute "direction" by which to judge progress, both are equally correct.

So this is where Dingle goes wrong: He uses rules from one game to analyze another and complains that the results don't make sense.

Hi Janus58 and thank you for your contribution.

Am I reading your post wrong, or did you read the Dingle quote wrong ? Most likely the former, but I should clarify in any case.

I don't think Dingle is implying absoluteness of the clock rates. I think he is saying that SRT requires it.

Thanks for your interesting example. In the paragraph I underlined, it seems you are saying something not at cross purposes with Dingle, ie, there is no absolute, and so, in the absense of observer C, who is right ? They can't both be right .. or something like that.

 

[Lakon]

Just a couple more points before I finish for the night.

1) I am not a cheer squad member for Dingle. He's just come up in some searches I done, I recalled mention of him here, so I read him. I must say though, I found him extremely erudite and whatever you may think of his relativity views, he seems to command some respect.

2) I am getting more confused by the day with this, and it's taking far more time from my obligations in life than what I can deal with. This of course, is no ones fault but mine. But I'll have to go a little light from here on (as though I've been heavy on you guys .. LOL ..)

Cheers all.

 

[Lakon]

Not accurate, see the post above. You can stop wasting your time reading the Dingle "book". It is a waste of time (you already wasted your money buying it).

Just one I missed, Tach - I didn't buy it. As I said in a post way above, it's a free PDF download.

 

[Tach]

Just one I missed, Tach - I didn't buy it. As I said in a post way above, it's a free PDF download.

A waste of time , then.