Relativity And Simple Algebra

[fahrquad]

Wow that pic of Alice is like looking in a mirror when I'm reading y'all's responses. Do you guys like cartoons? I bet you do. Here's one about my experiences on this forum:

 

https://www.youtube.com/watch?v=nX9OnI4yDrw

 

...So in cartoon language, if Homer's time is 5 and Marge's time is 4, their time difference is 1 to them. That same time diff of 1 is seen by everyone in the room even though everyone in the room may have different times on when Homer and Marge compared watches. But the key is that Homer and Marge can only establish their time diff when they're side by side. Homer can't yell across the room to Marge to ask what time she's got. Then no one will agree on their time difference or when they compared watches. It's like relativity defines co-location as a super perspective of time, like a present that's more real than the normally real perspective present. (This was a simplified example of faulty watches causing time diff but, in relativity, the time diff is real, the watches only record it.)...

 

Could you please re-state that in "Ren and Stimpy" terms so I can relate? 

 

https://www.youtube.com/embed/zRNPsd_PfeI

 

Why yes, I would like more blotter acid please.

Edited April 25, 2019 by fahrquad

[Amplituhedron]

 Why is that? Why are the time effects permanent but no permanent effect on length if the two happen concurrently to maintain the constancy of the speed of light. I can't wait to hear the answer.

 

Except you HAVE been given the answer: the clock that registers having run slower when the twins meet up again IS the residue of length contraction. When the twins meet, everything is the same for both again: clocks tick the same and lengths are the same for both. The twin that switched frames took a different path through spacetime than the stay-at-home twin. This has been explained to you for years, with no understanding on your part.

[Amplituhedron]

Not that this will make any difference to you, since you are a victim of the sunk-cost fallacy and will never admit you are wrong under any circumstances, but to say that the twin who switched frames should be “permanently length-contracted” when she meets up on earth again with her stay-at-home twin is a complete misconception of what has happened. The returning twin is not permanently time-dilated either! The twins’ clocks  again tick at the same rate when they meet up again. The corollary to the the traveling twin still being length contracted when she again shares the same frame with her twin, would be that when they are reunited, the formerly traveling twin’s clock is still ticking slower. Needless to say, this is NOT a prediction of SR, and indeed any such state of affairs would invalidate SR. Again, when the twins reunite, they are the same length and their clocks tick again at the same rate, BUT, the less elapsed time on the traveler’s clock IS the record of the length contraction.

[ralfcis]

No you have my attention. I don't remember ever hearing this before. The closest anyone has ever said to me that length contraction is permanent is through the calculations of it having happened during a spacetime path which is a circular argument to me. It's like saying the record of Alice seeing her distance length contracted is that she can travel 4ly in 3 of her years at .8c which would be 4/3 c if length contraction wasn't taken into account. This is a ridiculous argument to me as relativity has no speed limit of Alice's time covering Bob's space. That velocity is Yv which is not limited by c.

 

The returning twin may not experience continuing time dilation at the re-unification but she has permanently lost time. She may not be expected to continue being length contracted but it's a reasonable expectation that she may have permanently lost some length in the same way she lost time. Are you saying the length lost is converted into time and becomes part of the total time lost?

 

In my watch in an ice bucket analogy, the watch in the ice bucket runs slow, even physically shrinks but once out of the bucket it warms and never recovers the time it has lost but will recover its size. But in the analogy, time and size are not two sides of the same coin as space and time are in relativity. While I agree time dilation has nothing to do with the time permanently lost, if space = time as relativity says, there should be some way space can be lost the same way time is lost for the equation to be true.

Edited April 25, 2019 by ralfcis

[Amplituhedron]

Forget about relativity for a moment.

 

Bob and Alice live in a house at location A.

 

Exactly one block away on the same street is location B. B stands for “Bar.” Every night, Bob and Alice walk to the bar, get wasted, and then stagger home together, reeling and projectile vomiting the whole way.

 

BUT, Bob and Alice do not walk together TO the bar. They have different routines.

 

Alice, being the no-nonsense sort, walks straight down the block to the bar — the shortest possible distance.

 

Bob likes to take the scenic route. He walks a winding path that takes a lot longer. So he gets to the bar later than Alice does.

 

Now consider that Bob and Alice both carry stopwatches that are synced. When they leave the house at the same time, they simultaneously turn on their stopwatches. Each, then, when they arrive at the bar, immediately switches off his/her stopwatch. 

 

When they meet up at the bar, less time has elapsed on Alice’s stopwatch, than on Bob’s watch — obviously! There is nothing paradoxical about this, right? Alice’s  stopped watch may register two minutes for her trip. Bob’s stopped watch may register twenty minutes for his trip.

 

But what, exactly, are these watches recording? Time, of course, BUT … they are also recording distances. Alice’s stopped watch recording two minutes having elapsed is also a record of the shorter route she took through space — it’s a record, so to say, of length contraction relative to Bob!

 

Same exact thing happens when we fuse space and time into spacetime and take into account relativity. If space-traveling Alice switched frames relative to earthbound Bob, when they compare clocks, hers will show less elapsed time — but this is ALSO a record of a shorter spatial distance that she traveled. For Alice, whose ship clock ticks normally, the same way it did on earth, the distance between two celestial objects is contracted relative to Bob, so less time will have been found to elapse for her, when Alice and Bob meet again on earth.

 

So Alice’s clock is the record of length contraction. Both time dilation and length contraction are therefore accounted for by Alice’s clock.

 

If light itself had a point of view, and a stopwatch (it doesn’t have a POV or a stopwatch, but this is a gedanken experiment), and traveled directly from Bob and Alice’s house A to B (bar), it would travel no distance at all, in no time at all (from its POV). 

 

The upshot is that clocks measure both time AND distance, and so Alice’s relativistic clock in the twins though experiment just IS the permanent record of BOTH time dilation AND length contraction. And to reiterate, to suggest that Alice should somehow be permanently “flattened” when she reunites with Bob, is ludicrous, because if that were true, then when they reunite, her clock would also have to still be ticking slower than Bob’s — which, of course, it does not! If that bizarre state of affairs WERE true, relativity theory would be absolutely false!

 

To go back to the original setup, with Bob and Alice’s different routes to the bar, it would be like saying that when Bob got to the bar after twenty minutes, whereas Alice got there in only two minutes, then Bob should find, not only that less time elapsed on Alice’s stopwatch, but that also, Alice should be permanently flattened along her plane of forward motion, wrt  Bob. That would be an utterly ludicrous expectation — would you not agree? Why, then, would you have a different expectation for relativistic travel?

 

Therefore: relativistic space-traveling Alice’s clock, when compared again with stay-at-home Bob’s clock, just is the record of her length contraction relative to Bob.

[ralfcis]

Yes I understand this is relativity's explanation. I want to carefully respond and avoid arguing about the analogy and concentrate on the meaning of the analogy. 

 

1. The main equation of relativity is (c tau)² = (ct)² - x² where tau is proper time. Unlike the analogy, this equation states the one who travels through space will travel the shorter time. So the longer path in distance is done in less time unlike what we would think normally. So Bob's watch says he took less time even though he walked a further distance to the bar. This is all manufactured to keep c constant from all perspectives; length must contract when time dilates which results in maintaining the constant.  So the assumption becomes the conclusion; c can't be constant if there is no length contraction. I have a different explanation to keep c constant and to have space travel subtract from time duration without the need for length contraction.

 

2. I also spent time proving light does not travel no distance at all in no time at all. This would need to be true if length contraction was a fact.

 

3. From Alice's perspective, she'd say Bob looked flattened and Bob would say his path was shorter but neither illusion persists after they meet up. Alice had never moved through space and the assumption that Bob had to move over a contracted distance is not necessary. It can be simply explained that his clock slowed from Alice's perspective so he was able to cover that great distance in less of his time (which looked like it was ticking normally from his perspective). I'm saying no need to introduce a reality that doesn't persist once the conditions that caused it vanish. Relativistic results can be explained without bringing in length contraction. The theory of relativity can`t explain them without length contraction of which there is no permanent form of except as time. Why not get rid of the middleman.

 

I agree this has been explained to me countless times and I don`t reject it because I don`t understand it, I reject it because i have a far better explanation. The analogy you gave is not correct. Alice and Bob don`t race to the bar, they`re already at the bar and Bob flies to Cincinnati and returns for closing time at 3 am when his watch says its only 2 am. Alice wonders how she was just standing there and he had time to fly to Cincinnati and back in less time (according to his watch) than it took her to just stand there. His velocity change, not the supposedly contracted distance he travelled, is the reason for his permanently shorter time duration.

Edited April 26, 2019 by ralfcis

[Amplituhedron]

I assume you are familiar with the light clock? A rod with mirrors at each end is placed perpendicular upon a conveyance moving in constant uniform motion with respect to an observer in a rest frame. Light pulses bounce back and forth between the mirrors, up and down, ticking off the time. From the rest-frame point of view, the clock will tick slower than a rest frame light clock. I assume you understand why?

 

Now all one need do is place the same light clock parallel to the direction of motion, and length contraction automatically follows. If it did not, the speed of light would not be measured to be constant in all frames — which it always is.

 

[ralfcis]

I was not previously familiar with the parallel light clock thought experiment and I agree the theory of relativity has no choice but to explain the results in any way other than length contraction. I don't treat c as anything separate from any other velocity (except that it's speed of light through time is 2c as shown in a previous post). Just like the clock rate is the same within any frame, c is the same within any frame. The problems start occurring once you try to view frames from another perspective. While v and c are subject to the rules of relativity, Yv and Yc are not. These are velocities seen by an outside frame of another frame travelling through an invariant space using the time within the frame being observed. An outside observer will see that frame moving at v and light moving at c but the distance that is being covered by that frame is done in much shorter time. If you look at the STD where Alice is moving at  v=.6c, her Yv = .75c and her Yc = 1.25c. At v=.8c, her Yv = 1.333c and her Yc = 1.667 c. V and c do not break the rules but Yv and Yc are unlimited and actually appear in the STD while not appearing in any perspective. Time dilation alone ends up explaining the parallel light clock example without involving length contraction because the light traverses the rod's length in Yc=x/t' without violating v=x/t or c from any perspective.

 

This is difficult to accept because of relativity's brain washing but that same brainwashing dictates the muon experiment cannot be explained without invoking length contraction. I have previously shown in detail how this is not true. Once you understand that example, you will be able to understand how Yc does not violate c as the max speed limit.

Edited April 26, 2019 by ralfcis

[marcospolo]

Not that this will make any difference to you, since you are a victim of the sunk-cost fallacy and will never admit you are wrong under any circumstances, but to say that the twin who switched frames should be “permanently length-contracted” when she meets up on earth again with her stay-at-home twin is a complete misconception of what has happened. The returning twin is not permanently time-dilated either! The twins’ clocks  again tick at the same rate when they meet up again. The corollary to the the traveling twin still being length contracted when she again shares the same frame with her twin, would be that when they are reunited, the formerly traveling twin’s clock is still ticking slower. Needless to say, this is NOT a prediction of SR, and indeed any such state of affairs would invalidate SR. Again, when the twins reunite, they are the same length and their clocks tick again at the same rate, BUT, the less elapsed time on the traveler’s clock IS the record of the length contraction.

 

The trouble with this idea of length contraction at a certain velocity only in an inertial, non accelerating frame is simply that once the object returns to the same stationary state as the "Earth Twin"  the length is magically, inexplicably restored. 

 

So it must be true that at any measured lesser speed, the length shrinking effect is less and less till its finally nul.

The only way to decrease speed is to decelerate, and the only way to get from zero to any specific speed is to accelerate.

 

But SR does not work in acceleration frames! (it actually fails to work under any conditions!)

 

Are there tiny nano seconds at every stage of the acceleration and subsequent deceleration that we must pretend are "inertial", in order for the Length Dilated object to be able to return to normal size?

 

Fir instance, say the guy went fast enough that he is 1/10th his normal length. Now please explain how he manages to return to normal length, (Length Contraction on reverse) when at any given nano second he must STILL be proportionally length contracted, YET he MUST ALSO be in a decelerating frame?

 

If he is in a decelerating frame, and indeed he must be in order to get back to a stationary state, then SR cannot be applied, so the split second he touches the brakes, his instantly pops back to full size?  What say he touches the brakes, pops magically back to normal size, but then regains constant acceleration but at a slightly lesser velocity, does he also now instantly shrink somewhat? Does this hurt much?

 

Please explain how Length Contraction could possibly a considered a rational theory.

Seems that Relativists want the cake, and eat it too!

Edited April 27, 2019 by marcospolo

[ralfcis]

Marco, I don't want to defend length contraction to you but you're interpreting it all wrong. Just like time dilation, it can't be seen or felt or measured, it can only be calculated assuming Einstein's clock sync method or through light signal messaging. All time and space is normal within a frame. However, the only way to see time rate in slow motion or fast forward is by observing a broadcast video signal from the other frame. When the frames are separating, they will receive each others video in slow motion and if they're coming together, fast forward. Time dilation can't be in fast forward nor does it match the time rate observed in the video. But the clincher here is that while the video time rate is affected by velocity and direction, the size of the people in the videos will not be distorted. They will not look flatter or thicker which means there is no equivalent to a doppler shift ratio view of length contraction. At least this is what an experiment could determine. Raskar photos of light show a light pulse is not contracted to zero, it comes out the length set for it by the outside frame's proper distance. Also, as I said before when discussing the ladder paradox, the ladder is not length contracted, the ladder experiences a non-simultaneity of when the front and back doors open to give the illusion that a longer ladder can fit into a shorter barn. Nothing physically shrinks from any perspective.

 

PS. Some will argue that relativity does not apply to anything going at c but when light goes through water, it goes at .75c. If you took Raskar photos of a light pulse going through a horizontal tube of water, the lack of measurable length contraction of the light pulse could not be blamed on relativity's formulas not applying to things going at c. The only conclusion would be length contraction was dreamed up by Einstein and everyone buys it because Einstein said so.

Edited April 27, 2019 by ralfcis

[marcospolo]

Marco, I don't want to defend length contraction to you but you're interpreting it all wrong. Just like time dilation, it can't be seen or felt or measured, it can only be calculated assuming Einstein's clock sync method or through light signal messaging. All time and space is normal within a frame. However, the only way to see time rate in slow motion or fast forward is by observing a broadcast video signal from the other frame. When the frames are separating, they will receive each others video in slow motion and if they're coming together, fast forward. Time dilation can't be in fast forward nor does it match the time rate observed in the video. But the clincher here is that while the video time rate is affected by velocity and direction, the size of the people in the videos will not be distorted. They will not look flatter or thicker which means there is no equivalent to a doppler shift ratio view of length contraction. At least this is what an experiment could determine. Raskar photos of light show a light pulse is not contracted to zero, it comes out the length set for it by the outside frame's proper distance. Also, as I said before when discussing the ladder paradox, the ladder is not length contracted, the ladder experiences a non-simultaneity of when the front and back doors open to give the illusion that a longer ladder can fit into a shorter barn. Nothing physically shrinks from any perspective.

 

Your version of SR does not gel with the official version of modern Physics. They claim that both Time dDlation and Length Contraction are REAL physical effects, but that the victim does not realize it.  You are saying its all imaginary, to which I will add, therefore its not Physics.

In fact, the approved versions of SR claim that not only will the space ship shrink, but the distance between the ships departure and destination will also shrink!. That would mean that the Earth and Mars are actually moved closer together in reality for the fast moving ship!

AND that the ships occupant WILL really notice the shorter travel distance, but not notice that their time is slower.

 

The fact is that Relativists can't make up their mind what the hell to believe. If its so settled science, why all the arguing back and forth? If its settled, then all possible problems will have a set approved answer, but they don't.  Half the physicists have conflicting stories to the other half.

 

The only people making any sense are those that say that SR and GR are so crazy that they are not even wrong.

[ralfcis]

Imaginary is not what I mean. If you look shorter to me from a distance is that imaginary or an illusion of perspective. Light messages are real. If I send a message as I pass Mars that it took me 20 minutes by my watch while earth said from their perspective it should have taken 25 minutes then knowing perspective is involved allows one to calculate a time from any perspective but to say all those times are real is misleading. You look really shorter to me but you are not really shorter. However, my message from Mars will not include my perspective of the shortened distance to Mars. Mars' distance is fixed and Earth will know I travelled that distance at the speed of Yv using my time and the invariant distance.

[marcospolo]

Imaginary is not what I mean. If you look shorter to me from a distance is that imaginary or an illusion of perspective. Light messages are real. If I send a message as I pass Mars that it took me 20 minutes by my watch while earth said from their perspective it should have taken 25 minutes then knowing perspective is involved allows one to calculate a time from any perspective but to say all those times are real is misleading. You look really shorter to me but you are not really shorter. However, my message from Mars will not include my perspective of the shortened distance to Mars. Mars' distance is fixed and Earth will know I travelled that distance at the speed of Yv using my time and the invariant distance.

Great, so we totally agree that every claim of SR is but imaginary, as no physical changes to length or time occur for anyone, only that is what may SEEM to change, but only if they fail to take into consideration that affects of perspective, or the fact that their message system has a finite speed.

Allow for these things, and we have no possibility of any of Einstein's theories being real.

Because if, as you say, distance is invariant, then mathematically time must also be invariant.

Simply because velocity= distance  x time. 

We have the velocity, and we have the distance fixed, so therefore the other possibly "variable" ,  which is "time" must be actually a constant too!. Or the math won't work.

[ralfcis]

That's why I introduced proper time which is more invariant than perspective time but not totally invariant. A person making a velocity change will permanently affect the proper time on the proper simultaneity lines between them during the period of relative velocity imbalance between them. They do not share the same relative velocity so if distance is invariant, time must accommodate the velocity imbalance. I've spent a lot of time showing the math behind this. Relativity uses different math but it's only applicable to velocity changes that result in re-unification. That false limitation is a result of bad assumptions made by Einstein and without that limitation, his theory falls apart.

Edited December 21, 2019 by ralfcis

[marcospolo]

That's why I introduced causal time which is more invariant than perspective time but not totally invariant. A person making a velocity change will permanently affect the causal time between them during the period of relative velocity imbalance between them. They do not share the same relative velocity so if distance is invariant, time must accommodate the velocity imbalance. I've spent a lot of time showing the math behind this. Relativity uses different math but it's only applicable to velocity changes that result in re-unification. That false limitation is a result of bad assumptions made by Einstein and without that limitation, his theory falls apart.

and I would suggest that you also have made bad assumptions about the imagined requirement pertaining to time.

Why would one even consider that some modification of any of the measures, distance, speed and in your case, time, would be necessary?

Its not. The problem is imagined, the assumptions are false, but your proposed Math solution may be mathematically sound.  But Math is not Physics, its but a simple tool.

You've solved a problem that never existed in Physics. Its just an exercise in number crunching, not based on reality.

 

You seem to think that there is some "Velocity Imbalance", which is the mistake you have made.  There is no such imbalance, everything is OK with the world, no imbalance anywhere.

 

At any speed, or speed change, classical Physics has it covered nicely. Why invent imaginary unbalances then try to "fix" them.

Its only done to practice Math skills.

 

Edited April 27, 2019 by marcospolo

[ralfcis]

What specifically are my bad assumptions because the number crunching matches the physical results. But so does relativity's number crunching. Neither is enough to verify the theory behind the number crunching. However, I can crunch out more numbers than relativity can since I can calculate proper age difference for velocity changes that do not end in re-unification. The use of proper time allows me to do that. Is that my bad assumption?

Edited December 21, 2019 by ralfcis

[Amplituhedron]

The trouble with this idea of length contraction at a certain velocity only in an inertial, non accelerating frame is simply that once the object returns to the same stationary state as the "Earth Twin"  the length is magically, inexplicably restored. 

 

And, as I have pointed out, there is no permanent time dilation, either. When Bob and Alice meet up again in the same frame, their clocks are ticking in sync again, and of course they are the same length again.

 

What there is, rather, is a record of the person who switched frames — traveling Alice — wrt earthbound Bob. That record is the loss of time on Alice’s clock vis a vis Bob’s clock — the fact that Alice is actually younger. This is a record of time dilation and length contraction together.

 

Also, SR can be formulated without reference to accelerated frames at all. But of course that there are accelerated frames in the twin thought experiment is irrelevant. GR encompasses accelerated frames while keeping SR intact.

 

It is a funny thing how relativity denialists deny SR, when SR has been OBSERVED — the classic muon experiment, for example, which validates both time dilation and length contraction.

 

If you think these things are wrong, then scroll up to the link I gave to the light clock, one running perpendicular to the direction of motion and the other parallel to it, and show where the demonstration goes wrong. It doesn’t. Also, explain muons.