Is there a relativist in the crowd

@dalehileman,

dalehileman wrote:

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At the moment you appear confused about the actual effects of relativity.
Perhaps so Ros but in what way specifically

A number of ways. And if you would address my previous post we might be able to break them down.

But for example, your scenario involves clocks that all start at 12:00. But then later in your scenario you mention a clock that reads 11:55. Explain why you think one of the clocks would read 11:55.

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@rosborne979,

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Please stop introducing more people and more clocks, it's only making the scenario more difficult.

Sorry Ros but Marty was necessary to illustrate time-at-a-distance so we have three observers at the same location and same instant (noon) giving three different reports of the present clock reading on Mars, as you will see directly

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Beyond that, the above paragraph is wrong. Assuming that 12:00 (what I call 0) is the synchronized point at which all clocks start, then no clock will ever read 11:55.

If you will reread my postings still again once more Ros you will see that the synchronization was performed long before the time at which those reports are made

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it is again with your 4 clocks:

1. There are 4 clocks, all synchronized to 12:00. Two of them are on Mars and two of them are on Earth.

At the above instant there are 3 clocks at Earth and one on Mars as I believe you'll find pretty apparent from above

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2. At a certain instant, one of the Earth clocks goes to Mars and one of the Mars clocks goes to Earth….so they will read 12:00 when they arrive.

Obviojusly the confusion having arisen from your misunderstanding about Marty's trip, preceding Isaac's by 5 min

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3. The clocks that stayed in place each show 12:05 and the clocks that travelled each show 12:00 (approximately).

Of course Ros if you review all of the above you will see the reason for three different reports at noon Al's time, the critical instant where I illustrate the conventional, classical relativistic concept of time-at-a-distance, as I've said

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The fact that Marsha is there or whether someone stopped to visit anyone else doesn't matter.

Yes, in fact I seem to remember having posted that very observation in almost identical wording

Of course by now you can see that her clock had read 11:55 at Marty's departure

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Now, do you agree with that? We have to reach some common ground on which we agree,…....

By now Ros I suppose we'll be more nearly on the same track

So here we've discussed only the classical aspects of the four participants' observations. But now getting back to the OP, regarding my "posit", the alternate way to explain apparent changes in the moving object, as I've said, comment welcome from the dedicated relativist

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@dalehileman,

dalehileman wrote:

Sorry Ros but Marty was necessary to illustrate time-at-a-distance so we have three observers at the same location and same instant (noon) giving three different reports of the present clock reading on Mars, as you will see directly...At the above instant there are 3 clocks at Earth and one on Mars as I believe you'll find pretty apparent from above...Obviojusly the confusion having arisen from your misunderstanding about Marty's trip, preceding Isaac's by 5 min

You never said any of this before, which is making it almost impossible to understand what you are asking. Now I will have to pour over your scenario once again, adding in these (not so minor) details, to try to make sense of what you are asking.

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@rosborne979,

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You never said any of this before,

Pasting from OP:

At the moment in q, noon Al's time, Marty is just arriving from his home planet….

Third posting:

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What "home planet"?

Mars where Marty resides

Subsequently there are many postings reflecting Marty's trip. Perhaps you're unaware of page 1

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Now I will have to pour over your scenario once again

Yea Ros please do

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@dalehileman,

dalehileman wrote:

Is there a relativist in the crowd

I could be called a relativist... but only by comparison to some of the other folks here.

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Dahileman, when you talk about "relativists" like you do, it makes me wonder if you think that relativity is merely something that you can choose to believe in or not, like astrology or Scientology.

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@contrex,

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talk about "relativists" like you do

And Con how is that, exactly

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@DrewDad,

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I could be called a relativist...

Well then Dad welcome to our cheerful platoon

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@dalehileman,

dalehileman wrote:

Except, Bran, in my version when Isaac arrives at Mars, Marty had already left 5 minutes ago. Reason: His arrival at Earth noon makes it possible to better illustrate the concept of time-at-a-distance

Except that I'm not sure your version is valid. I'm sure that mine is.

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@dalehileman,

dalehileman wrote:

Subsequently there are many postings reflecting Marty's trip. Perhaps you're unaware of page 1

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Now I will have to pour over your scenario once again
Yea Ros please do

Ok, here's from your first post:

dalehileman wrote:

At another thread I attempt to explain my skewed view of relativity, a mere speculation, in the hope you might be able to help me clarify it for the benefit of at least a couple of other participants--or you know somebody who could

http://able2know.org/topic/232832-1

Background:

For sheer simplicity I posit three observers, Albert who's situated on the East Coast and two very sturdy travelers Isaac and Marty who pilot impossible rocket ships capable of instantly accelerating to c (almost). I've halted Mars at a distance of 5 light minutes or about 60 million miles, all clocks having been synchronized some time ago

You specify three observers, not four (Marsha is not mentioned) and no mention of how many clocks. Clocks are synchronized but you don't specify at what time they are synchronized. This makes it extremely difficult to deduce the actual setup of your thought experiment. But anyway...

dalehileman wrote:

At the moment in q, noon Al's time, Marty is just arriving from his home planet while Isaac is just taking off

It's clear at this point (since Marty left from Mars) that the clocks must have been synchronized at 11:55.

At this point Al's clock reads 12:00 and Marty's clock reads 11:55, Isaac's clock probably also reads 12:00 but that's assuming that he's taking off from Earth and not Mars (which isn't specified).

dalehileman wrote:

My view simply emphasizes Isaac's notion that it's 5 minutes later,

Later than what?

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@Brandon9000,

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Except that I'm not sure your version is valid.

I'm not either

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I'm sure that mine is.

Why then Bran don't you describe it

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@dalehileman,

dalehileman wrote:

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Except that I'm not sure your version is valid.

I'm not either

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I'm sure that mine is.

Why then Bran don't you describe it

I did describe it. Read it again. There is no more.

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@rosborne979,

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You specify three observers, not four (Marsha is not mentioned)

Yea Ros I might have introduced her a bit later in order to clarify something about Isaac's trip--perhaps as a result of somebody's comment regarding the "end" of the two travelers' various trips

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Clocks are synchronized but you don't specify at what time they are synchronized.

To the contrary I do remember having mentioned it was done some time before Al's noon moment of special interest. However please don't ask me to go look for it since yardwork is calling

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...the clocks must have been synchronized at 11:55

Yes of course, or at some time earlier. I don't see how you might have gained the impression that I had omitted such a detail unless again perhaps somehow you had lost page 1

dalehileman wrote:
My view simply emphasizes Isaac's notion that it's 5 minutes later,

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Later than what?

Five minutes later on Mars than on Earth. Golly I was sure I had covered all this but I apologize again for any confusion

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@Brandon9000,

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I did describe it. Read it again. There is no more.

Sorry Bran I'm getting woozy. I presume you're speaking of time-at-a-distance so if you could provide a link to the pertinent posting I'd be much obliged

Edited to admit, yes you did give me your version in posting #…..545, to which I replied in #……142, agreeing pretty much with your except correcting your misunderstanding about the time of Marty's departure

So otherwise how is it mine differs from yours, pray

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@dalehileman,

dalehileman wrote:

Quote:
I did describe it. Read it again. There is no more.
Sorry Bran I'm getting woozy. I presume you're speaking of time-at-a-distance so if you could provide a link to the pertinent posting I'd be much obliged

Edited to admit, yes you did give me your version in posting #…..545, to which I replied in #……142, agreeing pretty much with your except correcting your misunderstanding about the time of Marty's departure

So otherwise how is it mine differs from yours, pray

Yours has a lot of extra stuff that's irrelevant. If someone departs from a non-accelerated location, accelerates to near the speed of light compared to that location, travels at that relative speed for a time, returns, and decelerates to match the speed of that location again, less time will seem to have passed to the traveler than to another person who stayed behind. The factor is SQRT(1 - v^2/c^2). That's time dilation. Anything you add is irrelevant. I don't have the time or the inclination to pore through poorly phrased irrelevancies until I can formulate a disproof.

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@Brandon9000,

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until I can formulate a disproof

Okay Bran it's all right, but a disproof of what

You summary of time dilation pretty much agrees with all I know about it. Maybe you mean the loopy way I've described looking at time-at-a-distance and yes, I could be dead wrong, but don't feel obliged to comment further as I know how yardwork seems to pile up

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@dalehileman,

dalehileman wrote:

Quote:
Later than what?
Five minutes later on Mars than on Earth. Golly I was sure I had covered all this but I apologize again for any confusion

Does Isaac not know that he just travelled to Mars at the speed of light? Is that why you are suggesting that he doesn't understand why his clock is out of sync with the clock on Mars?

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@dalehileman,

Are you suggesting that Isaac should pre-set his clock to 12:05 before he departs so that when he arrives on Mars it will already match Mars time? In other words, that when we look at distant objects that we should pre-set our definition of the object with a time value that we know relates to their distance from us?

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@rosborne979,

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Does Isaac not know that he just travelled to Mars at the speed of light? Is that why you are suggesting that he doesn't understand why his clock is out of sync with the clock on Mars?

I don't recall suggesting that's what he suggested. According to classical relativity, to Isaac at noon Al's time when he fires his rocket, the moment of significance, it actually is 12:05 on Mars, just as it's 11:55 according to Marty. All three understand relativity and appreciate the others' viewpoint

That's what's meant by time-at-a-distance. Carrying it a step further, however, once he's arrived at his destination I'm suggesting to Isaac that another possible reason his trip seemed so fast isn't because his clock had stopped (as in Al and Martha's view) but that his trip was instantaneous

Of course in my weird posit, it's also the reason Al sees him apparently shrinking, getting more massive, etc

So he's given permission to adopt either view. Admittedly of course mine is still up for grabs

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Are you suggesting that Isaac should pre-set his clock to 12:05 before he departs so that when he arrives on Mars it will already match Mars time?

No but he has my permission

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In other words, that when we look at distant objects that we should pre-set our definition of the object with a time value that we know relates to their distance from us?

Not exactly. If you will review my former postings still again once more you will see that with my prop we assume that actually is 12:05 there

At risk of repetition, revisiting still once again, replay of recapitulation; at any point in the Universe the time at distance d is thus t = d/c. I describe this as "favoring" Isaac's view at his launch, and ask Al to accept it also, explaining so much more easily all the peculiarities Isaac seems to undergo and why no matter how much fuel he uses he can never achieve exactly c

(Somewhat OT Ros but Isaac's situation is essentially identical to one in which our galaxy collection, that's all of 'em we can see, constitute only a peripheral fraction of the total, but owing to the Big Bang it's actually traveling at (ok, very near) c. So when Isaac fires his thrusters he actually becomes stationary

So in that scenario, even by classical relativity, his trip indeed is instantaneous)

Indeed the classical concept of t-at-a-d is a tough idea to grasp in the first place, much less my alternate speculation. I hope it's all a little clearer and again thanks Ros for your participation, with my apologies for any apparent lack of clarity

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@dalehileman,

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(Somewhat OT Ros…... owing to the Big Bang it's actually traveling at (ok, very near) c. So when Isaac fires his thrusters he actually becomes stationary

With apology just realized this might not make sense since the Universe doesn't have a "center" by which to judge our galaxy's velocity--Or Isaac's, it's all relative

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Is there a relativist in the crowd

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