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michel123456's relativity thread (from Time dilation dependence on direction)

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37 minutes ago, michel123456 said:

And 1 hour behind, the Earth was closer to him. So he is observing the earth larger (because of regular perspective). And because of length contraction, he is observing the Earth flattened.

Oh my... Our traveler sees the same light arriving from earth as the man in the bar. So they see the same. So according to you the man in the bar sees the earth suddenly bigger, because the traveler entered the bar??? Or maybe, maybe, when the traveler stops at the bar, he sees exactly what the man already sitting in the bar sees? Just the usual angular size as everybody else on 1 LH distance?

54 minutes ago, Eise said:

and I want your interpretation of why muons reach the surface.

Still waiting. Or do you start to see the problem with your interpretation?

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3 hours ago, Eise said:

Oh my... Our traveler sees the same light arriving from earth as the man in the bar. So they see the same.

Let's take it from the start.

At time zero A & B are at rest looking at planet X that is 1LH away.

Out of magic, B steps instantly into a FOR that travels at 0.8c.

What does B sees? Doesn't he sees planet X length contracted? And closer to him? Instantly? While observer A sees it normal as usual?

Or am I wrong there too?

Edited by michel123456

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28 minutes ago, michel123456 said:

Let's take it from the start.

At time zero A & B are at rest looking at planet X that is 1LH away.

Out of magic, B steps instantly into a FOR that travels at 0.8c.

What does B sees? Doesn't he sees planet X length contracted? And closer to him? Instantly? While observer A sees it normal as usual?

Or am I wrong there too?

B would see X as length-contracted (not that he can actually see through the planet to notice this), and also see planet X (that is 1 LH away according to A) as being only 0.6 LH away. According to B's clock, the trip will take 45 minutes. According to A's clock it will take an hour and fifteen minutes. 

All of this has been explained, multiple times, starting with Janus in the fourth post of the thread. It's not going to change.

 

 

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13 minutes ago, michel123456 said:

Let's take it from the start.

At time zero A & B are at rest looking at planet X that is 1LH away.

Out of magic, B steps instantly into a FOR that travels at 0.8c.

What does B sees? Doesn't he sees planet X length contracted? And closer to him? Instantly? While observer A sees it normal as usual?

Or am I wrong there too?

Yes, you are wrong.  You are again confusing what someone visually "sees", and what they would determine as being true at that moment.

He would "see" exactly the same light as he saw before he made the jump* However, the conclusions he would make based on what he sees and his relative velocity to planet X would be that Planet X is closer and length contracted at that moment. 

It is important to separate the "optical" effects due to Relativistic velocity differences from the actual Relativistic effects. For example while according to you, an object flying by you at .8c would be length contracted, visually you would see it rotating as it passed you.  This "Terrell rotation" is an optical effect, which doesn't represent an actual rotation of the object according to you, but the length contraction is measured as a physical change.

This distinction between what one "sees" and what they "determine" seems to be something you struggle with.

 

* There would be an aberration effect which would distort the image of planet X for him, But that would occur with or without Relativity( just to a different degree).  And this aberration would vanish just as quickly if he were to come to a rest again with respect to Planet X.

 

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1 hour ago, swansont said:

B would see X as length-contracted (not that he can actually see through the planet to notice this), and also see planet X (that is 1 LH away according to A) as being only 0.6 LH away. According to B's clock, the trip will take 45 minutes. According to A's clock it will take an hour and fifteen minutes. 

All of this has been explained, multiple times, starting with Janus in the fourth post of the thread. It's not going to change.

 

 

So you seem to agree that A & B would see different things although getting the same light. If that does not hurt your feelings at the departure, why is it so mind blowing at the arrival at planet X?

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33 minutes ago, michel123456 said:

So you seem to agree that A & B would see different things although getting the same light. If that does not hurt your feelings at the departure, why is it so mind blowing at the arrival at planet X?

Again A and B would visually "see" the same thing. They would conclude a different state of things.

B is at rest with, and 1 light hour from planet X as measured by either. A is moving at 0.8c relative to both, and is passing B on his way to planet X.  As A and B pass, they see the same light that came from Planet X.

B concludes that the light left 1 hr ago and took one hour to reach him across the 1 light hr distance separating them.

A however, has to reason like this:

"I am now seeing light from Planet X, while I am next to B, This light was traveling at c relative to me, and had to have left planet X before I was next to B, and when the distance between Planet X and myself was much greater than it is at this moment now, when I am next to B  Planet X was 3 light hrs away from me when the light left, to be exact. It took 3 hrs for that light to reach me, during which time, The distance between planet X and myself decreased at 0.8c to  3lh -(3h*0.8c) = 0.6 light hrs.  Thus as I am passing B, planet X is 0.6 light hrs from me ( even though the light I am now seeing left it when it was 3 light hrs from me) "

A and B see exactly the same light from Planet X as they pass each other, but reach different conclusions as to how far away planet X is at that moment.

A can reaffirm his conclusion by waiting until he and planet X meet up, which will occur in 45 min by A's clock.   45 min * .8c =  36 light min = 0.6 light hrs.

 

 

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On 9/17/2020 at 3:25 PM, michel123456 said:

Third problem is length contraction happening only in the direction of movement. I wonder how that can happen, while time dilation has no direction. How are the 2 effects compatible? (it would make more sense if length contraction happened in all directions. More sense if length contraction was a kind of illusion, a kind of perspective effect and not a real thing.

It does only happen in the direction of motion as is or would be derived from the Lorentz transformation. If you have some other mathematical model to propose in which the object doesn't just contract in the direction of motion but in every direction equally or by some function of the velocity be my guest. . . propose it and test it. Further, "time dilation has no direction" why does this have to be a problem. . . why is this a problem for length contraction? Again you can propose some inhomogeneity or anisotropic effects that if a clock went in one direction it would slow more than in another in a round trip. . . be my guest in mathematically realizing this and testing it.  

On 9/17/2020 at 3:25 PM, michel123456 said:

Fourth problem is with multiple realities; how is it possible for all observers to measure different realities (different times & lengths) and that these realities are all existing at the same time: aka you have a rod 1 meter long in your hand but some other observer in a moving car tells you that you are wrong, the rod is 90 centimeters. If someone told you that you would probably answer that you know better, the rod is 1meter long, point. What the other observer is measuring is a distorted image, it is not a 2nd reality.

You cannot just assume there is this immaterial Newtonian Clock that ticks throughout the universe and some how also minimally interacts with everything in the process assigning a precise time measurement anywhere in the universe. . . you cannot just claim this by fiat.

Further, you literally DO NOT HAVE TO LEAVE GALILEAN RELATIVITY or classical physics to have your "multiple realities". Remember the Galilean transformation? Through this transformation you can transform from one INERTIAL frame to another without issue and thusly could show that the laws of physics (conservation of energy/linear and angular momentum) were followed in both frames of reference just as YOU will see the other frame moving away from you with some velocity (they are not identical frames of reference then) according to your frame of reference. . . wait. . . but the velocity was opposite that way in the other inertial frame of reference. . . which is the right velocity? In which the answer to said question is that this is a nonsense question as only a velocity assigned to a particular frame of reference (even the almighty stationary one) is what matters as you can only ask what velocity an object has with RESPECT to a particular frame of reference. In special relativity this idea is merely extended to measurements of lengths as well as clock ticks seen from your frame of reference. 

On 9/17/2020 at 3:25 PM, michel123456 said:

Ah yes, fifth problem: the twin paradox. The paradox is not about one twin aging more or less than the other. The paradox is that there is a broken symmetry: the traveling twin is aging less than the twin who stays at rest. But since the traveling twin is also in a resting FOR (a different one), who is the traveling twin? twin A or twin B? Which of the 2 twins will age less than the other? It is not logically acceptable that both twins will age less than the other. That is the paradox. And there is something wrong in it.(and not endless conversations about accelerations in order to determine who is the traveler & who is at rest, that is not the problem)

And maybe more. 

Again, you do not need to leave classical physics to see the fault in seeing this as a problem. Imagine you have a spaceship and a lone spaceman out in the middle of space at rest with respect to each other. The spaceship rockets away accelerating up then slows down to speed up in the opposite direction before slowing down again to enter the original frame of reference it resided in at the beginning. You both ask each other who really moved?

First Person: I clearly didn't as I saw you speed away and during the whole time I remained at rest with respect to myself. I wasn't moving.

Second Person: But I also saw myself as at rest the whole time. 

When you think about it kinematically and visually they both have some grounds to consider themselves both correct as there space-time diagrams would show similar but oppositely oriented collections of parabolic curves. To alleviate the issue we decide to mount an apprautus to the spaceship that is basically a small ball within a larger ball where the smaller ball is floating freely but the larger ball is attached to the spaceship. If we accelerated forward then the freely floating ball would just slowly float in the air until the now moving outer surface closed the distance and then impacted it. If we were in an inertial frame of reference the whole time then clearly the ball within there would just float as you would expect via our classical understanding of physics and inertial frames of reference (frames without any induced forces). You then both repeat the same experiment and predictably the floating spaceman would never notice any forces (fictitious or real) creep into his frame of reference while those in the spaceship would see their smaller ball begin to move as if some force was exerted on it but (assuming they accounted for all other forces) this cannot be as it clearly must remain inertial as we accounted for all forces. The only real answer is that a force was exerted on the spaceship which gave rise to our fictitious force on the ball. Thus the paradox is solved. . . the spaceship was the one that moved. 

With two inertial frames of reference (one moving away at constant velocity) you couldn't really do this because the paradox requires the frames come back together and if they both accelerated away then came back together they would still see the fictitious forces arise in their respective frames of reference. 

Just as in Galilean or classical physics there is NO RELATIVITY OF NON-INERTIAL FRAMES OF REFERENCE so is the case in special relativity because. . . you know. . . its first postulate is that all inertial frames of reference are equivalent not ALL NON-INERTIAL FRAMES OF REFERENCE ARE EQUIVALENT or ALL FRAMES OF REFERENCE ARE EQUIVALENT. Which would be required for the twin paradox in that one of them has to turn around so to speak or both equally turn around but in the process in both situations their are people objectively changing inertial frames of reference. In the later case, however, given they accelerated for the same amount of proper time (slowed then speed up to come back) they would have identical world lines and there wouldn't be any net time difference with respect to each other when they re-enter the original inertial frame of reference because they would be entirely symmetric. . . the people in the original frame of reference however would notice that they were both equally younger assuming they remained inertial (we could as an experiment or mathematically set up a similar ball apparatus as before). 

On 9/18/2020 at 2:44 AM, michel123456 said:

Not to say that the laws of optics should be derived from Relativity, since it is a theory that deals with what is being observed.

This is an issue I see all the time in people trying to grasp relativity. In the theory (with minimal ontological assumptions of Minkowski spacetime) while you have this effect of length contraction that is rather mathematically explicit even by theory or ontology what you would actually observe is something like. . . Animated_Terrell_Rotation_-_Cube.gif.826392720aa377b16ead0471b11a2ead.gif

In fact I'm pretty sure there is even a further different classical perspective of the cube that you would expect which does differ from the visual image seen above that special relativity would, being approximately correct, in the end expect. 

 

@swansont How'd I do? 

Edited by The victorious truther

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6 hours ago, The victorious truther said:

 

On 9/18/2020 at 10:44 AM, michel123456 said:

Not to say that the laws of optics should be derived from Relativity, since it is a theory that deals with what is being observed.

This is an issue I see all the time in people trying to grasp relativity. In the theory (with minimal ontological assumptions of Minkowski spacetime) while you have this effect of length contraction that is rather mathematically explicit even by theory or ontology what you would actually observe is something like. . . Animated_Terrell_Rotation_-_Cube.gif.826392720aa377b16ead0471b11a2ead.gif

In fact I'm pretty sure there is even a further different classical perspective of the cube that you would expect which does differ from the visual image seen above that special relativity would, being approximately correct, in the end expect. 

 

That is worth a separate thread. Some Moderator will send me a warning & do the job (I hope) with a link here for those interested.

A comment from Swansont about the same topic some posts above says:

21 hours ago, swansont said:

This is a geometry/perspective issue, not one of relativity. They are distinct effects and have to be treated as such. The perspective issue should be easy to incorporate and separate from analysis, because it's an everyday effect. But it doesn't go away simply because of relativity. 

 

The laws of perspective (that try to represent our visual  everyday experience) say that an object that gets away from you is seen as if its size was diminishing, and an object that gets close to you is seen as getting larger. Of course the object does not change size in "reality", it is simply an effect of optics, but as I read here, it is completely ignored in Relativity. The moving examples posted above by V.T. do not care about this perspective effect.

 

From Wiki

Quote

Linear perspective is an approximate representation, generally on a flat surface, of an image as it is seen by the eye. The most characteristic features of linear perspective are that objects appear smaller as their distance from the observer increases, and that they are subject to foreshortening, meaning that an object's dimensions along the line of sight appear shorter than its dimensions across the line of sight. All objects will recede to points in the distance, usually along the horizon line,

What is foreshortening:

https://drawpaintacademy.com/foreshortening/

1463198187_ScreenShot09-22-20at10_54AM.JPG.78326aa2c725aa2a248bfa460f60011e.JPG

 

The analogy with length contraction is pure coincidence, I guess.

Or not. Are the laws of physics a single thing that enties everything ( the way we see things on a daily basis), or are the laws of perspective totally independent of Relativity? (as it seems to be the case at first sight).

And respectively, can Relativity ignore the fact that objects appear smaller as their distance from the observer increase? And not taking count of this effect when representing the distortion of objects that move at near to c velocity?

Edited by michel123456

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On 9/21/2020 at 10:39 AM, michel123456 said:

Like the "multiple reality" argument

It has been pointed out to you multiple times already that there is no such thing as "multiple realities" in a classical model such as SR/GR. It seems to me that in fact you are the only one here attempting to use this as an argument.

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3 hours ago, michel123456 said:

 The laws of perspective (that try to represent our visual  everyday experience) say that an object that gets away from you is seen as if its size was diminishing, and an object that gets close to you is seen as getting larger. Of course the object does not change size in "reality", it is simply an effect of optics, but as I read here, it is completely ignored in Relativity. The moving examples posted above by V.T. do not care about this perspective effect.

Right. it’s a separate effect, and as such, not part of relativity. You account for the effects independent of relativity, because they manifest themselves independently 

 

Quote

And respectively, can Relativity ignore the fact that objects appear smaller as their distance from the observer increase? And not taking count of this effect when representing the distortion of objects that move at near to c velocity?

You don’t care if a clock appears smaller, and we know that the visual size is not the measured size. As has been pointed out, what you see and what you measure are not the same, and it’s time you stopped interchanging the two.

 

Quote

The analogy with length contraction is pure coincidence, I guess.

Perhaps, but this confirms that you can handle the concept of something visually looking longer or shorter does not mean that its measured length has changed. 

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5 hours ago, michel123456 said:

The analogy with length contraction is pure coincidence, I guess.

No, it's not. Length and time contraction are some kind of foreshortening. But the angle analogue is v/c, and it's based on the geometry of a hyperbola, not of a sphere (or circle). But never mind that now. And it is an observer-dependent effect. If for some reason you are thinking that the object you're looking at doesn't have the length you seem to perceive, you may choose to change the angle and you'll see something different.

But exactly the same as the foreshortened arm has a proper length (invariant), moving objects have a proper time (their co-moving time).

About 'twins' trips:

Exactly the same as you can go from one corner of a square 9 m² room (of 3 m-wide walls) to the contiguous one along the wall, measuring a distance of 3 meters, you may decide go to the contiguous corner the long way, by sequentially covering the other two corners, and cover 9 m (3+3+3) around the other direction. That's exactly the same that happens to the non-inertial twin that went around to the same place on a non-inertial trip. The first twin has gone along a flat wall and has noticed nothing significant. The non-inertial twin has had to cross two corners and has noticed curvature.

I'm not sure I'm helping with this alternative explanation. If not, feel free to ignore me.

I'm amazed by the patience displayed here by almost everybody else here, TBH. They don't give up on you. They just don't.

I confess my inability as of today of concocting such careful and detailed Alice-Bob analyses as have been offered to you. I have a tendency to search for shortcuts.

Edit: Rather than shortcuts, to concentrate on the formalism and learn to relax about puzzling un-intuitive notions. I do mistrust my intuitive notions.

Edited by joigus

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6 hours ago, michel123456 said:

That is worth a separate thread. Some Moderator will send me a warning & do the job (I hope) with a link here for those interested.

A comment from Swansont about the same topic some posts above says:

Please do so but i'm not sure I trust you with deriving the visual results from special relativity on what you would see so when you get there stick to classical physics. . . unless you can show us the mathematical rigor needed. 

6 hours ago, michel123456 said:

The laws of perspective (that try to represent our visual  everyday experience) say that an object that gets away from you is seen as if its size was diminishing, and an object that gets close to you is seen as getting larger.

Yes, there is also a classical assumption that would play into this and give rather predictive results as to how it would exactly look. Cut your teeth on this article I found. 

6 hours ago, michel123456 said:

Of course the object does not change size in "reality", it is simply an effect of optics, but as I read here, it is completely ignored in Relativity. The moving examples posted above by V.T. do not care about this perspective effect.

Hmmmm. . . I found it! There is a difference between length contraction (measured) and what is observed which respectively would be (b) versus (c) as well as what you would expect with naive classical physics (e). 

PWAug19Appell-fig2a_1200-635x1518.thumb.jpg.3bcf8b17e2fa148b5944b78341af7626.jpg

(a) A row of dice at rest moving from left to right in a single file at 95% of the speed of light. (b) The moving dice are length contracted, so that one might (wrongly) expect them to look as here. (c) If you actually observe the dice, however, they will appear rotated. (d) But when some perception in depth is provided, you’d see them as sheared rather than rotated. (e) Shown here is the predicted “classical” appearance of the dice, with no length contraction. You can view a short film of part c online here. (Courtesy: U Kraus 2008 Eur. J. Phys. 29 1)

6 hours ago, michel123456 said:

Or not. Are the laws of physics a single thing that enties everything ( the way we see things on a daily basis), or are the laws of perspective totally independent of Relativity? (as it seems to be the case at first sight).

And respectively, can Relativity ignore the fact that objects appear smaller as their distance from the observer increase? And not taking count of this effect when representing the distortion of objects that move at near to c velocity?

You better have read the articles above and looked at the image as well as considered that there is a strong difference between what length you measure an object to have and distorted image you see.  

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7 hours ago, michel123456 said:

The laws of perspective (that try to represent our visual  everyday experience) say that an object that gets away from you is seen as if its size was diminishing, and an object that gets close to you is seen as getting larger. Of course the object does not change size in "reality", it is simply an effect of optics, but as I read here, it is completely ignored in Relativity. The moving examples posted above by V.T. do not care about this perspective effect.

The perspective effect is due to the fact that objects of the same size subtend a smaller angle of your visual field as the distance to them increases.

If the observer is moving relative to the object, a second visual effect also has to be taken into account: aberration.

Aberration affects the angle at which you will see the light coming from.  In the case where you are looking at an object coming towards you, the angle tightens inward making the object "look" smaller.

So let's go back to my last example:

A and B both see light coming from planet X as they pass each other.  They see the same light.  The difference is that due to aberration, A sees the light come from a smaller angle, and visually "sees" a smaller image.  Now this is not inconsistent with what I said about what he concludes, which is that the light he is now seeing left planet X when it was 3 light hrs from him, thus he would expect to "see" a smaller image.

The point is that there is nothing about what A "sees" that runs contrary to, or is inconsistent with, what Relativity says is happening.  Relativity usually ignores these secondary "visual" effects, not because it can't deal or account for them, but because at best, They don't tell us anything important, and at worst, they add unnecessary "clutter" to the scenario.  

 

 

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5 minutes ago, Janus said:

The perspective effect is due to the fact that objects of the same size subtend a smaller angle of your visual field as the distance to them increases.

And this is true while at rest, so it’s not an effect of special relativity. SR is an effect of relative motion.

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4 hours ago, The victorious truther said:

Thanks for the interesting visuals, they're rarely shown.

From what I understand, the only(?) differences between the length-contracted measured (b) and the seen (c) are abberation of light (where the orientation of a ray of light is different in different frames of reference, due to the time that it takes light to travel from source to destination while those points are moving) as well as different parts of the scene being seen in different positions due to delay of light from different distances.

The rotation seen must be a rotation in 4 dimensions, nothing is rotated in 3? To demonstrate, if you add rails that the dice slide on (say 4 rails that 4 edges of each die slide on), such that the rails are at rest relative to the observer, you'll see of course that the rails do not appear distorted, and that the dice edges never appear to leave the rails. For example, the tops of the 1-side of the dice still appear to follow an undistorted straight line, and the bottoms of the 1s follow another, and same with the 6-side at the back. When moving in the x direction, an objects's parts don't rotate off their yx coordinates, but instead appear stretched between them. That can also be seen in the black and white animation you posted earlier.

Edit: I just noticed, the (d) image shows this... Instead of rails, have the dice slide along lines in the floor. It looks like the checkered floor is at rest relative to the observer, and each die has the same width and proper length as a floor tile. The sides of the dice appear remaining aligned with the straight floor tiles. The description also describes them as sheared, not rotated, but the shearing is how the 4D rotation appears in 3D?

Edit2: No wait... I think there are 2 separate things. A hyperbolic rotation of lengths and times, between the x and t dimensions (y and z are not affected at all if there's no motion in those directions) and the superficial appearance of the objects appearing rotated. The observable effect of the actual rotation is length contraction. The distortion that appears similar to a rotation isn't a rotation at all, but shearing. The entire front (in direction of travel) of a die passes the parallel floor lines simultaneously, both in the die's frame and this observer's frame, but appears not to because the die face isn't all the same distance to the camera.

Edited by md65536

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7 minutes ago, md65536 said:

Thanks for the interesting visuals, they're rarely shown.

So true numerous different misconceptions in relativity or perhaps other areas of physics could be alleviated with sort of thinking. 

8 minutes ago, md65536 said:

From what I understand, the only(?) difference between the length-contracted measured (b) and the seen (c) is the effect of abberation of light, where the orientation of a ray of light is different in different frames of reference, due to the time that it takes light to travel from source to destination while those points are moving.

The time it has to travel as well as where and when it was emitted as even in your frame of reference in special relativity it's perfectly possible to imagine being in the cube's frame to emit light equally in all directions at the same time but others will not see it in the same manner you would expect. 

10 minutes ago, md65536 said:

The rotation seen must be a rotation in 4 dimensions, nothing is rotated in 3? To demonstrate, if you add rails that the dice slide on (say 4 rails that 4 edges of each die slide on), such that the rails are at rest relative to the observer, you'll see of course that the rails do not appear distorted, and that the dice edges never appear to leave the rails. For example, the tops of the 1-side of the dice still appear to follow an undistorted straight line, and the bottoms of the 1s follow another, and same with the 6-side at the back. When moving in the x direction, an objects's parts don't rotate off their yx coordinates, but instead appear stretched between them. That can also be seen in the black and white animation you posted earlier.

You know I think you may be rather right in your speculation but i'd have to investigate further mathematically. 

@md65536 Also. . . Steins Gate. . . NICE! 

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3 hours ago, Janus said:

So let's go back to my last example:

A and B both see light coming from planet X as they pass each other.  They see the same light.  The difference is that due to aberration, A sees the light come from a smaller angle, and visually "sees" a smaller image.  Now this is not inconsistent with what I said about what he concludes, which is that the light he is now seeing left planet X when it was 3 light hrs from him, thus he would expect to "see" a smaller image.

That is the point, why is it not inconsistent? As you say, the image of planet X  at 3 LH that the traveler A observes when bypassing B is different than the image of planet X at 1 LH as seen by resting observer B. It is not a small difference. 3 times farther means 9 times smaller.

6 hours ago, joigus said:

About 'twins' trips:

Exactly the same as you can go from one corner of a square 9 m² room (of 3 m-wide walls) to the contiguous one along the wall, measuring a distance of 3 meters, you may decide go to the contiguous corner the long way, by sequentially covering the other two corners, and cover 9 m (3+3+3) around the other direction. That's exactly the same that happens to the non-inertial twin that went around to the same place on a non-inertial trip. The first twin has gone along a flat wall and has noticed nothing significant. The non-inertial twin has had to cross two corners and has noticed curvature.

Nicely presented. Except that intuition would say that the guy who covered the long path through the corners would be older than the one going straight away, while the result of the twin paradox is the contrary.

@Janus could you please continue your example & describe what traveler A observes when reaching planet X? Thank you.

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12 hours ago, michel123456 said:

The analogy with length contraction is pure coincidence, I guess.

Or not. Are the laws of physics a single thing that enties everything ( the way we see things on a daily basis), or are the laws of perspective totally independent of Relativity? (as it seems to be the case at first sight).

And respectively, can Relativity ignore the fact that objects appear smaller as their distance from the observer increase? And not taking count of this effect when representing the distortion of objects that move at near to c velocity?

The arm does look smaller or larger depending on your perspective. . . but if you actually made a measurement and sent a light beam (or a radio signal or even used a measuring rod that was at rest with respect to your arm) you would happen to find the length had remained unchanged in BOTH situations. So. . . no length contraction. . . bad analogy. 

When you talk about the laws of perspective being independent of Relativity note the difference between what a camera or perhaps even a human being could potentially see and what kind of raw measurements we could make in which these sort of perceptual effects wouldn't come into it. You get the SAME PERCEPTUAL effects in CLASSICAL PHYSICS and we rightly so do not designate them as actual length changes but this is because of the specific collection of dynamical/kinematical laws we are assuming to then analyze this. The same is in special relativity in which length contraction is usually treated as the sort of frame dependent observation that is consistent with Lorentzian transformations while what you would see is (c) instead of (b) so you CANNOT go off of pure visual observations so to speak to find this contraction but you would measurably notice it in special relativity,

PWAug19Appell-fig2a_1200-635x1518.thumb.jpg.7a0e73252c9146de461f811686fc10f6.jpg 

Not only that. . . are you just going to ignore the meat of my previous posts. . . anything to say. . . the laws of optics are not ignored in special relativity rather they are amended yielding the above image (c) rather than the classical optical image (e). If you desire to chalk it up to CLASSICAL OPTICS then please be my guest and explain how this can be the case that in special relativity we seem to measure/record lengths as being shorter when in reality they are not supposed to be but we measure them as. 

Further, there isn't entirely something wrong with the philosophical question of whether it's the dynamical laws that give rise to or are fundamental to the kinematical ones or vice versa as other philosophers in spacetime philosophy have claimed that dynamical symmetries must be symmetries of spacetime. Dissenters have argued that we should flip the arrow of explanation from the kinematically explaining dynamical laws (spacetime structure -> dynamical laws) to seeing them as rather fundamental (dynamical laws -> spacetime structure). The question then of whether the Lorentz length contraction is more real in one perspective or the other one isn't really a question that would get a wrong answer in this situation as if we emphasized dynamical considerations then the objects from other perspectives do contract seemingly (dynamical laws require us to measure them as shortened) or it's the spacetime structure that results in our. . . wait for it. . . length measurements to result in being shorter. In either situation it wouldn't be any less real or entirely more perceptual

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5 minutes ago, The victorious truther said:

Not only that. . . are you just going to ignore the meat of my previous posts. . . anything to say. . .

Michel has established that he's spent 20 years denying relativity. There are many, many hijacked threads over the decades, any that have certain keywords (in this case, "time, direction"), turned into 6+ pages of failed attempts to get him personally to accept something about SR. He's stated in this thread that he's not interested in relativity, and of all the hundreds and hundreds of answers to his repeated questions, not a single one of them he acknowledges as an answer to his questions. The only time I've seen any calculation or attempt to work through a problem, is when he's twisting his beliefs and made-up definitions into a nonsensical answer that confirms that relativity is wrong. Trying to understand relativity is destructive to his goals, and completely avoided. So the answer is yes, anything that shows relativity working will be ignored. If you're enjoying explaining it, that's good. If you're hoping Michel will learn something, ... I wouldn't.

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1 hour ago, michel123456 said:

Nicely presented. Except that intuition would say that the guy who covered the long path through the corners would be older than the one going straight away, while the result of the twin paradox is the contrary.

You would think this if you didn't consult the spacetime interval in which \( s^{2} = (ct)^{2} - x^{2} = (c\tau)^{2}\). NOTE that the traveler happens to have a longer path through spacetime and together with the objectively long path they traveled in space some of that distance in SPACETIME that they happened to traverse has some of that temporal component eaten up by the distance they traveled. 

The spacetime interval for the person at rest is: 

\[ \tau = t_{person at rest} \]

For the twin who (because he was non-inertial) was objectively traveling a longer path through spacetime they started and ended the journey at the same spot yielding in terms of the rest frame time \( \tau \) or it took \( \tau \) time for them to leave then come back: 

\[  (c\tau)^{2} = (ct_{traveler})^{2} + x^{2} \]

They traveled objectively some certain distance \( x \) and using your knowledge of pythagorean theorem you notice that the length of the one side (the time by the traveler) couldn't exceed the length of the two others. Objectively given they traveled away there was no way the time of the traveler could in fact exceed or even equal that of the time given by the clock at rest if it must abide by special relativity and likewise the spacetime interval. 

\[ t_{traveler} \neq \tau \]

@joigus Did I do this right? 

14 minutes ago, md65536 said:

Michel has established that he's spent 20 years denying relativity. There are many, many hijacked threads over the decades, any that have certain keywords (in this case, "time, direction"), turned into 6+ pages of failed attempts to get him personally to accept something about SR. He's stated in this thread that he's not interested in relativity, and of all the hundreds and hundreds of answers to his repeated questions, not a single one of them he acknowledges as an answer to his questions. The only time I've seen any calculation or attempt to work through a problem, is when he's twisting his beliefs and made-up definitions into a nonsensical answer that confirms that relativity is wrong. Trying to understand relativity is destructive to his goals, and completely avoided. So the answer is yes, anything that shows relativity working will be ignored. If you're enjoying explaining it, that's good. If you're hoping Michel will learn something, ... I wouldn't.

Always bound to come across somebody like this on any forum. . .

Edited by The victorious truther

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3 hours ago, michel123456 said:

Nicely presented. Except that intuition would say that the guy who covered the long path through the corners would be older than the one going straight away, while the result of the twin paradox is the contrary.

Time for the free falling trajectory is actually a maximum, not a minimum.

Unintuitive? Perhaps, but that's the way it is.

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As I wrote, for each answer I get, more questions raise:

1432370208_ScreenShot09-23-20at09.46AM2.jpg.813a05824084eec4015b742fb9833672.jpg( my error corrected)

Quest1. Why is the distance d2 larger than the distance d1? Shouldn't it be contracted?

Quest2. Why is the red distance smaller than the orange one? I am counting 4 intervals for the red one (4 squares) and 8 or more for the orange one. If the cube is moving at constant velocity, the 2 lines should be equal.

And I have to admit that I had in mind picture B. I was wrong again as it seems. But I still don't know why: in this picture B everything looks fine.

 

 

8 hours ago, joigus said:

Time for the free falling trajectory is actually a maximum, not a minimum.

Unintuitive? Perhaps, but that's the way it is.

Good point. That's a good input for the "what is time" thread.

 

Edited by michel123456

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7 hours ago, michel123456 said:

Quest1. Why is the distance d2 larger than the distance d1? Shouldn't it be contracted?

How about you go through the mathematics and create an image plane with the relativistic object having its light happen to reach some focus then figure it out. It's difficult and perhaps not actually correct to analyze some image analysis as has been given as we do not know what the units were nor whether your naive perceptual decision on what is longer is truly correct. Should the image of a cube appear larger than it should in the way you claim or is this not what special relativity would predict optically? Remember, no "I think it would look like this," just do the mathematics or perhaps wait for some one competent in that respective to show it in a simplified situation.  

7 hours ago, michel123456 said:

Quest2. Why is the red distance smaller than the orange one? I am counting 4 intervals for the red one (4 squares) and 8 or more for the orange one. If the cube is moving at constant velocity, the 2 lines should be equal.

A simple imaging plane and a focus will construe the image like that as objects farther to the left will appear more scrunched together i'm assuming. . . we're talking about what you would see optically. In fact. . . just you wait as i'll perform the some mathematical investigation into this but derived via some simple vector mechanics with objects being focused unto an imaging plane with a focus. Then we can compare the images showing that those objects farther away parallel wise to the imaging plane do seem to have their distance scrunched up even if we happen to possess an equally dispersed series of lines in reality

7 hours ago, michel123456 said:

And I have to admit that I had in mind picture B. I was wrong again as it seems. But I still don't know why: in this picture B everything looks fine.

Glad you admit your fault and you must please understand that you should not use your intuition as if it's a judicial gavel of physics as even in CLASSICAL PHYSICS with optical imaging i'm willing to bet we could both make similar mistakes in thinking if we didn't actually do the proper mathematical preliminaries to derive how things would actually play out. I'll attempt to get back to you as soon as possible for the classical then the special relativistic case with all proper mathematical foundations. I'll be using equally spaced constant velocity rods then for both the classical as well as the relativistic to compare. 

 

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7 hours ago, michel123456 said:

As I wrote, for each answer I get, more questions raise:

1432370208_ScreenShot09-23-20at09.46AM2.jpg.813a05824084eec4015b742fb9833672.jpg( my error corrected)

Quest1. Why is the distance d2 larger than the distance d1? Shouldn't it be contracted?

Is the “length” moving? No. So it’s not contracted.

The picture depicts the object (die) moving, and pictured at different times. Basically like snapshots put into the same picture.

 

7 hours ago, michel123456 said:

Quest2. Why is the red distance smaller than the orange one? I am counting 4 intervals for the red one (4 squares) and 8 or more for the orange one. If the cube is moving at constant velocity, the 2 lines should be equal.

Because that’s how it was drawn. The distance between the pictures is irrelevant to the discussion. The objects gave to be depicted with enough space between them so they don’t overlap, in order to see them clearly.

 

 

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7 minutes ago, swansont said:

The picture depicts the object (die) moving, and pictured at different times. Basically like snapshots put into the same picture.

In the description is declares that it's a row of dice moving. Not a single (die) pictured at different times while it was moving if I recall correctly. 

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