Why in the world would Einstein suggest....

@layman,

Quote:

I'm not sure if that responds to your question about what is "contrary to Al's theory," though. Does it, or is your question something else?

Yes I hear what you're saying, and I have to agree the temptation to assume that "stationary ref" is very strong indeed

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@barmpot,

Your link, Barm, seems to indicate, contrary to Lay's position, that it's the acceleration that makes the traveler's clock slow

I had assumed all my 84 years that Al had settled this matter but apparently not

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@dalehileman,

Al has settled the matter or we can all throw away our satnavs ! The travelers clock has NOT "gone slow". His trajectory in space-time between comparison points on take off and landing is "shorter" due to his acceleration.

The fact is Dale that we can all be deemed to be "traveling" with respect to something...1000 mph round the earth....67,000 mph round the sun.....500,000 mph round the center of the galaxy. Layman seems to have forgotten that when he tries to play childish games with Chicago.

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@barmpot,

Quote:

His trajectory in space-time between comparison points on take off and landing is "shorter" due to his acceleration.

And yet Barm this link seems to deny any effect of acceleration, which would seem to say that after my circumnavigation of the Universe, on my return to Earth from the opposite direction I should find you and I both at the same age as when I left

http://en.wikipedia.org/wiki/Clock_hypothesis

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@dalehileman,

No. You missed the link there to "proper time"

Quote:

In relativity, proper time along a world line is the time as measured by a clock following that line. The proper time interval between two events depends not only on the events but also the world line connecting them, and hence on the motion of the clock between the events. An accelerated clock will measure a smaller elapsed time between two events than that measured by a non-accelerated (inertial) clock between the same two events. The twin paradox is an example of this effect.

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barmpot, I think you're wasting your breath here.

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@contrex,

Quote:

barmpot, I think you're wasting your breath here.

I gotta admit Con is right, and I am confused about the supposed effect of acceleration. If you and I pass at a relative speed near c, each of us sees the other's clock as stopped. But what has me going is this: Does it matter which one of us had accelerated in order to achieve this relative speed

Another issue: If the Universe is finite, will we meet again coming from opposite directions; will which of us had accelerated have any effect on our respective ages at this meeting

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@dalehileman,

Yes it matters. The fact that each of our clocks appears to be "slow" to the other during the constant velocity stage is undetectable on our own aging with our own instruments in our own isolated reference frame. Our instruments "see" the other as "younger" It only "actually" matters when our "world lines" meet and we can compare ages side by side in the same reference frame. The accelerated world line is shorter than the inertial one between conjoint points. Remember that "points" are events in space-time not merely locations in space.

Seeing as Younger ?
Think about astronomical observations "seeing into the past" of distant objects. That should help you understand the "appearance vs actuality" issue.

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@barmpot,

Quote:

Al has settled the matter or we can all throw away our satnavs ! The travelers clock has NOT "gone slow"

That's not what Al himself says, Barm. He has written expositions on SR where he clearly and distinctly says that the clocks of moving observers run slower.

I might add that this is also exactly what's indicated by the math relevant to SR (the Lorentz transformations).

From what I can tell, your own references also say otherwise. You quoted an explanation of proper time, for example, which said:

Quote:

The proper time interval between two events depends...on the motion of the clock between the events. An accelerated clock will measure a smaller elapsed time between two events... .

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@barmpot,

Quote:

The fact is Dale that we can all be deemed to be "traveling" with respect to something...1000 mph round the earth....67,000 mph round the sun.....500,000 mph round the center of the galaxy. Layman seems to have forgotten that when he tries to play childish games with Chicago

1. Why would you think I "forgot" that? I was only talking about the relative motion between 2 particular observers (a guy on the ground and a guy on a train).

2. Did Al also "forget," you figure? Because I am merely using his example, and his explanation, not one of my own creation.

How is your (accurate) claim that "we can all be deemed to be "traveling" with respect to something" even relevant here, Barm?

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@layman,

Quote:

That's not what Al himself says, Barm. He has written expositions on SR where he clearly and distinctly says that the clocks of moving observers run slower

Chapter and verse please. I can handle the original German.

You clearly seem to have no clue about the fundamental significance of the axiom of the constancy of c for all observers and its role in what is "observed" from each reference frame That is where Einstein departed from Lorentz. Without that understanding you will continue to produce waffle.

BTW "motion of a clock" can mean refer either to its mechanism or its path through space-time (the world line). The twins issue is about the latter..

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@dalehileman,

Quote:

Your link, Barm, seems to indicate, contrary to Lay's position, that it's the acceleration that makes the traveler's clock slow

That's not really "my" position, Dale, which I think you'll see if you read my post(s) on the topic.

I think it is clear that, according to the physicists, acceleration, per se, does NOT make the traveler's clock run slow.

An increase in relative speed does, but that is just the by-product of acceleration. The acceleration itself has no effect whatsoever on the amount of time dilation experienced by the traveler.

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@barmpot,

Quote:

You clearly seem to have no clue about the fundamental significance of the axiom of the constancy of c for all observers and its role in what is "observed" from each reference frame That is where Einstein departed from Lorentz

Likewise, Barm, you seem to have no clue about the fundamental difference between "not understanding" what a person say with "not agreeing" with what a person says.

Al's conception of "relative simultaneity" is NOT necessary to explain our experience (as many, perhaps you included, seem to think). It is a possible explanation, and, mathematically, at least, it is self-consistent. But other theories, which assume that simultaneity is absolute, not relative, also completely explain our experience, and make all the same predictions, just as accurately, as SR does.

Each and every experiment which is deemed to "confirm" SR also "confirm" those theories (which incorporate a preferred frame, such as the CMB).

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@layman,

Chapter and verse please.

Put up or shut up !

Lorentz tried to cling to the "aether" in support of Clerk-Maxwell but QM later reconstructed Maxwell's equations without it.

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@barmpot,

Quote:

Put up or shut up !

What? You've never read what Al says on the topic? I can find some relevant excerpts, but it might take some time

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@layman,

I have all the time in the world for you to find a reference where Al said the "moving" observer's clock actually runs slower rather than appears to run slower.

Waiting................................................................... . . .

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@barmpot,

Quote:

I have all the time in the world for you to find a reference where Al said the "moving" observer's clock actually runs slower rather than appears to run slower

I'll find it, but, to clarify let me ask you: Just exactly what distinction are you trying to make between "actually runs slower" and "appears to run slower?"

Let me make it more concrete. Take two different scenarios:

Case 1: One clock is boarded on an airplane for a transatlantic flight. When the flight lands, that clock has recorded less time elapsed than has the ground clock it was previously synchronized with.

Case 2.: Same scenario, but when the plane lands both clocks show an identical amount of time elapsed and any prior impression that the plane clock was, or would be, running slower was just a false "appearance."

Case 1 is "actually running slower," case 2 is only "apparently" running slower. Are you saying that Case 2 would be the result?

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@barmpot,

Quote:

You clearly seem to have no clue about the fundamental significance of the axiom of the constancy of c for all observers and its role in what is "observed" from each reference frame That is where Einstein departed from Lorentz.

I believe you are quite mistaken about that. That is not where Al "departed from" Lorentz (whose math calculations he himself used in SR). Both agreed that every observer in every inertial frame would "observe" the speed of light to be constant.

Lorentz' transformations were created to give an exact mathematical form to the adjustments that would have to be made between frames to explain this curious fact.

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@barmpot,

BTW, Barm, I am awaiting your response to my request for clarification before pursuing quotations from Al.

I'm not gunna go on some wild goose that if you're looking for something other than what you appear to be asking for.

If, for example, you said "There are pink elephants 50 feet below the surface of the moon. Show me any place where Al says there aren't," I wouldn't bother.

Obviously Al would never specifically refute such an absurd notion.

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@barmpot,

Quote:

..."actually" matters when our "world lines" meet...

….which supposedly would be when one or both of us had circumnavigated the Universe and we meet again coming back from the opposite direction--so would we then find ourselves the same age

Maybe that link you provide--and thanks for it--wold answer this q. I shall get to it

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Why in the world would Einstein suggest....

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