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

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3 hours ago, Markus Hanke said:

Exactly  Relativity treats time and space on equal footing -

So long as this is not meant to mean that space and time are themselves the same, since there are differences.

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3 hours ago, michel123456 said:

Because what the traveler sees is the same (the mirror) of what the observer on earth sees.

When the traveler goes out, as much the distance to the Earth increases, as much the delay increases too. And on the return trip, as much the distance reduces, so reduces the delay. The turning point will not be reached at the middle point (in time) of the travel. Although it will be the middle point in distance.

And the delay can be accounted for, as has been explained a dozen times. There's nothing magical about it. It's just math. (it's not really different than realizing that if you kick the ball to where someone is right now, but they're running, it will miss. You kick the ball to where they will be - you take into account the time it takes the ball to travel)

3 hours ago, michel123456 said:

If the clock makes the U-turn at the middle point in time, at the end of the travel the clock will miss the Earth by a distance corresponding to the delay

Miss? How can it miss? It goes out and comes straight back. It's a 1-dimensional example

3 hours ago, michel123456 said:

(if I am correct, this is more a guess than an accurate calculation).

That's a huge part of the problem here.

3 hours ago, michel123456 said:

Check with Janus example.

Janus gave a correct explanation. The traveling twin does not miss the earth on the return trip.

3 hours ago, Markus Hanke said:

Relativity is a purely classical model based on the notion of local realism, so of course there is only one reality. It couldn’t be any different. The one major difference compared to Newtonian mechanics is that measurements of time and space are now purely local concepts, so in order to describe a global reality, you need to consider a different set of quantities - namely those that are invariant.

To add to this: The thing everyone agrees on are events. If something happens in one frame, it happens in all frames. But they will not agree on certain measurements: time, distance, energy, etc. since those depend on your frame of reference.

If there are two events, observers might not even agree on which one happened first.

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12 hours ago, michel123456 said:
13 hours ago, md65536 said:

The trip that I described is realistic. If you travel outbound at one speed, and return at the same speed, it will take you the same time to make each leg of the trip. Galilean relativity even agrees with that.

Galilean relativity yes., but not Relativity (because of SOL).

What? Of course the out- and inbound trips take the same time in Galilean and Einsteinian relativity. Same speed, same distance, and therefore same time. The 'only' discrepancy is between both relativity principles.

Take the example of flying to a star that has a fixed position seen from the earth, i.e. the star and the earth are in the same reference frame.

In Galilean relativity:

• Traveler's view: travels the distance to the star with its speed and back with the same speed. His speed he can correctly derive from the distance traveled and the time on its own clock. But of course on the outbound trip, he sees a clock on earth running slow. But he knows this is just because the increasing delay. On the inbound trip, he sees exactly the opposite, the earth's clock is running fast. When he ends his journey back on earth his clock, and the earth's clock show the same time again.
• Earth's view: more or less the same as the view from the traveler. On the outbound trip the traveler's clock seems to run slow, on the inbound fast, and at the end of the trip the clocks show the same time again.

Both agree on: the distance traveled and on the time it took.

In Einsteinian relativity:

• Traveler's view: the distance between the star and earth has become smaller, however the speed is the same. So the traveler sees he arrives at the star faster, because the distance is smaller. Returning with the same speed (but opposite direction!, i.e. the traveler changed his reference frame), of course the distance will be shortened by the same amount as the outbound trip. Looking at the clock on earth on his outbound trip he sees it slowed down because on one side the delay, but on the other side the time dilation. Flying back he still sees the time dilation, but also the effect of nearing the earth's clock. So depending on the speed, he sees the earth's clock, ticking faster, but not as fast as in Galilean relativity.
• Earth's view: the trip takes just as long on earth's clock as in Galilean relativity, but from the earth the traveler's clock is running slow to time dilation. So from the earth, using the clock of the traveler, the trip takes the same time, but not according earth's own clock. On the inbound trip the same happens. So the traveler's clock runs slower than in Galilean relativity.

For short:

• the traveler did fly a shorter distance than seen from earth, therefore he has not grown older as fast as the earth.
• for the earth the clock of the traveler ran slow, therefore the traveler has not grown older as fast as the earth.

So they both agree about reality. Just as the example of the muons: they reach the earth's surface.

@michel123456: When do you explain to us why muons can arrive the earth's surface, even if, using Galilean relativity, they live too short to reach the earth's surface? You never seem to answer any of the challenging questions we ask, or show us where our arguments are wrong. You only show us where the results of our arguments conflict with your picture of reality.

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11 hours ago, michel123456 said:

Because what the traveler sees is the same (the mirror) of what the observer on earth sees.

No he doesn't. Because, since the traveler has to undergo a change of velocity at the end of his outbound leg in order to return to the Earth, he will see a change in the  frequency of light he receives from the Earth when he makes that velocity change.  There is no delay.   He sees the Earth clock tick at 1/3 speed for 45 min by his clock and thus accumulating 15 min, and then sees it ticking 3 times as fast for 45 min, accumulating  2 hrs, 15 min. Thus he sees the Earth clock accumulate 2 1/2 hrs while his own clock ticked off 1 1/2 hrs.

The Earth observer has to wait to see the result of the velocity change because it takes place 1 light hr from him. The traveler doesn't have to wait, because he is the one making the velocity change, so it is happening where he is.

I never addressed what the traveler would have seen before this.  You jumped to an erroneous conclusion regarding what the traveler would see.

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1 hour ago, Janus said:

No he doesn't. Because, since the traveler has to undergo a change of velocity at the end of his outbound leg in order to return to the Earth, he will see a change in the  frequency of light he receives from the Earth when he makes that velocity change.  There is no delay.   He sees the Earth clock tick at 1/3 speed for 45 min by his clock and thus accumulating 15 min, and then sees it ticking 3 times as fast for 45 min, accumulating  2 hrs, 15 min. Thus he sees the Earth clock accumulate 2 1/2 hrs while his own clock ticked off 1 1/2 hrs.

The Earth observer has to wait to see the result of the velocity change because it takes place 1 light hr from him. The traveler doesn't have to wait, because he is the one making the velocity change, so it is happening where he is.

I never addressed what the traveler would have seen before this.  You jumped to an erroneous conclusion regarding what the traveler would see.

When the traveler makes the U-turn, he sees the Earth still getting away from him. He will see the Earth stop going away and begin the rush at him some minutes after he made the U-turn, because there is a delay. The image of the Earth takes some time to go to the traveler.

See it otherwise: if the traveler stopped for a drink at destination, he would see the image of the Earth stop getting away from him after 1 hour. (approx 4 beers in Belgian units)

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2 minutes ago, michel123456 said:

He will see the Earth stop going away and begin the rush at him some minutes after he made the U-turn, because there is a delay.

How many minutes will it take? What formula do you use to calculate that?

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12 minutes ago, zapatos said:

How many minutes will it take? What formula do you use to calculate that?

As I wrote above: if he stopped, it is 60 minutes aka1 hour (because he is 1 HL away). If he makes the U-turn immediately it gets complicated because you have to count for the velocity after the U-turn. It is this instant that Janus describes when the traveler is going back but observer on the Earth haven't seen the U-turn yet.

But we have not reached an agreement on what is happening. Basically I am the bad guy disagreeing with everybody.

Edited by michel123456
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30 minutes ago, michel123456 said:

See it otherwise: if the traveler stopped for a drink at destination, he would see the image of the Earth stop getting away from him after 1 hour. (approx 4 beers in Belgian units)

So you are seriously saying that if our traveler stopped for a beer with a friend who was already at the bar, that the traveler would see the earth moving away from him while his friend would see the earth as NOT moving away?

You are not trying, this is not reflective of 20 years of study.

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1 hour ago, michel123456 said:

As I wrote above: if he stopped, it is 60 minutes aka1 hour (because he is 1 HL away). If he makes the U-turn immediately it gets complicated because you have to count for the velocity after the U-turn. It is this instant that Janus describes when the traveler is going back but observer on the Earth haven't seen the U-turn yet.

No. A signal will take an hour to get there, but light is continuously sent. The traveler will immediately see the earth get closer, from photons emitted an hour (or slightly less) earlier

Quote

But we have not reached an agreement on what is happening. Basically I am the bad guy disagreeing with everybody.

Disagreeing without scientific justification. If you think there is a delay, show the math.

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1 hour ago, michel123456 said:

When the traveler makes the U-turn, he sees the Earth still getting away from him. He will see the Earth stop going away and begin the rush at him some minutes after he made the U-turn, because there is a delay. The image of the Earth takes some time to go to the traveler.

See it otherwise: if the traveler stopped for a drink at destination, he would see the image of the Earth stop getting away from him after 1 hour. (approx 4 beers in Belgian units)

As Bufofrog has already pointed out, this would mean that two people, at the same spot and at rest with respect to each other would see two different things happening to the Earth for an hour. This is impossible, as the same light from the Earth is reaching both of them simultaneously at any given moment of that hr.  Your claim leads to a physical contradiction.

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2 hours ago, michel123456 said:

As I wrote above: if he stopped, it is 60 minutes aka1 hour (because he is 1 HL away). If he makes the U-turn immediately it gets complicated because you have to count for the velocity after the U-turn. It is this instant that Janus describes when the traveler is going back but observer on the Earth haven't seen the U-turn yet.

But we have not reached an agreement on what is happening. Basically I am the bad guy disagreeing with everybody.

I have never studied Relativity and even I know that is wrong.

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19 hours ago, studiot said:

So long as this is not meant to mean that space and time are themselves the same, since there are differences.

Yes, of course there are differences, which is why I used the term “on equal footing” instead They are treated the same, which is different from being the same.

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9 hours ago, swansont said:

No. A signal will take an hour to get there, but light is continuously sent. The traveler will immediately see the earth get closer, from photons emitted an hour (or slightly less) earlier

Disagreeing without scientific justification. If you think there is a delay, show the math.

There must be a delay. If I am wrong, then the delay is somewhere else. Go and find it.

As observed from the Earth, the image of the traveler going away is delayed. So logically speaking, the image of the Earth that as seen by the traveler is delayed too. There is no reason why one observer would see a delay and the other not.

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11 hours ago, michel123456 said:

When the traveler makes the U-turn, he sees the Earth still getting away from him. He will see the Earth stop going away and begin the rush at him some minutes after he made the U-turn, because there is a delay. The image of the Earth takes some time to go to the traveler.

46 minutes ago, michel123456 said:

There must be a delay. If I am wrong, then the delay is somewhere else. Go and find it.

The delay is in what any observer in the bar sees happening on earth. So the traveler and the person living there see exactly the same: what happens on earth one hour ago. That is your delay.

On his outbound trip the traveler notices an increasing delay. This increase stops when he stops traveling. If you are moving you see your starting point moving away. But the moment you stop, this moving away stops immediately. Otherwise you get the contradiction that Bufofrog and Janus pointed you to.

Even Zapatos understands that!

And when do I get your explanation that we can see muons reaching the surface of the earth? What does it look like for an observer on earth, and what does it look like from the FOR of the muon?

I assume you cannot answer it, if I don't get an answer.

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1 hour ago, Eise said:

The delay is in what any observer in the bar sees happening on earth. So the traveler and the person living there see exactly the same: what happens on earth one hour ago. That is your delay.

But if the traveler looks behind him just before stopping, he will see the earth as it was in the past 1 hour ago. At this time (1hour ago) the Earth was closer to him. Because he is in a state of motion he sees things differently than the observer at rest at the bar.*

1 hour ago, Eise said:

And when do I get your explanation that we can see muons reaching the surface of the earth? What does it look like for an observer on earth, and what does it look like from the FOR of the muon?

I assume you cannot answer it, if I don't get an answer.

You know that you are right, and I know it. If you read my previous posts more carefully you may understand than I don't want to counter the mathematics of Relativity. I am against some interpretations of relativity. Like the "multiple reality" argument, or like the present discussion.

* And yes I was wrong. I forgot that when the traveler stops he jumps into another FOR and he must see what other people are seeing from this FOR.

Edited by michel123456
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Other members are doing a good job describing what actually happens in nature. So I try a different path, describing consequences of your description and see where that may take the discussion. I hope the questions may trigger som thinking regarding your current understanding in relation to the models available in mainstream physics.

14 hours ago, michel123456 said:

See it otherwise: if the traveler stopped for a drink at destination, he would see the image of the Earth stop getting away from him after 1 hour. (approx 4 beers in Belgian units)

I have some trouble with all the paradoxes that follows from the description and why you would believe in such scenarios. Maybe I have not understood your ideas. Let's assume that your description correctly describes what happens.

Questions:

1: If the traveler* and the bar tender** takes simultaneous photos of the earth from the bar, will the images look different according to your understanding? If they switch cameras with each other will that change anything?

2: If the traveler had followed a curved or "s"-formed path earlier, how does that affect what he is supposed to see? While the earth is still getting away from the traveler 1 hour after the traveler has stopped, does the earth also move sideways to reflect the earlier curves os "s"-bends?

Edit: X-post with michel123456; my questions above are not applicable any more:

1 hour ago, michel123456 said:

* And yes I was wrong. I forgot that when the traveler stops he jumps into another FOR and he must see what other people are seeing from this FOR.

*) That is, the person that just traveled
**) an individual that was at the destination already, and has been there for an extended amount of time

Edited by Ghideon
format, x-post with michel123456
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15 minutes ago, Ghideon said:

Other members are doing a good job describing what actually happens in nature. So I try a different path, describing consequences of your description and see where that may take the discussion. I hope the questions may trigger som thinking regarding your current understanding in relation to the models available in mainstream physics.

I have some trouble with all the paradoxes that follows from the description and why you would believe in such scenarios. Maybe I have not understood your ideas. Let's assume that your description correctly describes what happens.

Questions:

1: If the traveler* and the bar tender** takes simultaneous photos of the earth from the bar, will the images look different according to your understanding? If they switch cameras with each other will that change anything?

2: If the traveler had followed a curved or "s"-formed path earlier, how does that affect what he is supposed to see? While the earth is still getting away from the traveler 1 hour after the traveler has stopped, does the earth also move sideways to reflect the earlier curves os "s"-bends?

*) That is, the person that just traveled
**) an individual that was at the destination already, and has been there for an extended amount of time

I was wrong. See above.

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2 hours ago, michel123456 said:

There must be a delay. If I am wrong, then the delay is somewhere else. Go and find it.

As observed from the Earth, the image of the traveler going away is delayed. So logically speaking, the image of the Earth that as seen by the traveler is delayed too. There is no reason why one observer would see a delay and the other not.

There is a delay, which they both see. The light from the earth takes an hour to get to the traveler. But the light is continuously sent. It's not sent every hour, like the clock signals everyone has discussed. But you identified two delays - the light travel time, and the delay before the twin sees the earth getting closer, after turnaround. The first exists. The second does not.

If you go 1 LH away and stop, you will get light that was sent from earth an hour earlier. If you turn around and go back, when you've moved 1 LS, you will get light that left the earth 59 minutes and 59 seconds ago.The earth will take up an incrementally larger solid angle on your screen (assuming sufficient resolution) because you are closer to the source. There is no delay in noticing this; that light was already en route.

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3 minutes ago, swansont said:

There is a delay, which they both see. The light from the earth takes an hour to get to the traveler. But the light is continuously sent. It's not sent every hour, like the clock signals everyone has discussed. But you identified two delays - the light travel time, and the delay before the twin sees the earth getting closer, after turnaround. The first exists. The second does not.

If you go 1 LH away and stop, you will get light that was sent from earth an hour earlier. If you turn around and go back, when you've moved 1 LS, you will get light that left the earth 59 minutes and 59 seconds ago.The earth will take up an incrementally larger solid angle on your screen (assuming sufficient resolution) because you are closer to the source. There is no delay in noticing this; that light was already en route.

Yes, but (quoting myself)

44 minutes ago, michel123456 said:

But if the traveler looks behind him just before stopping, he will see the earth as it was in the past 1 hour ago. At this time (1hour ago) the Earth was closer to him. Because he is in a state of motion he sees things differently than the observer at rest at the bar.*

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41 minutes ago, michel123456 said:

But if the traveler looks behind him just before stopping, he will see the earth as it was in the past 1 hour ago. At this time (1hour ago) the Earth was closer to him. Because he is in a state of motion he sees things differently than the observer at rest at the bar.*

As long he is moving away from earth, yes, he sees earth clocks go slow, but as soon as he stops at the bar, his clock and earth clocks go in the same pace. But, yes, the earth clocks seem to be one hour behind. That is the delay due to the distance.

44 minutes ago, michel123456 said:

* And yes I was wrong. I forgot that when the traveler stops he jumps into another FOR and he must see what other people are seeing from this FOR.

Right. At least a first step...

39 minutes ago, michel123456 said:

You know that you are right, and I know it. If you read my previous posts more carefully you may understand than I don't want to counter the mathematics of Relativity. I am against some interpretations of relativity.

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

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48 minutes ago, michel123456 said:

You know that you are right, and I know it. If you read my previous posts more carefully you may understand than I don't want to counter the mathematics of Relativity. I am against some interpretations of relativity. Like the "multiple reality" argument, or like the present discussion.

That there are no preferred frames, so that all measurements are equally valid, is based on one of the postulates of relativity. To deny that is to deny the validity of relativity, and there really isn't any "interpretation" that gets you around this.

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1 minute ago, Eise said:

As long he is moving away from earth, yes, he sees earth clocks go slow, but as soon as he stops at the bar, his clock and earth clocks go in the same pace. But, yes, the earth clocks seem to be one hour behind. That is the delay due to the distance.

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.

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49 minutes ago, michel123456 said:

But if the traveler looks behind him just before stopping, he will see the earth as it was in the past 1 hour ago. At this time (1hour ago) the Earth was closer to him.

The earth doesn't "know" where an observer is. The lights leaving the earth doesn't care about any potential observers. It will spread out, decreasing in intensity with approximately a 1/r^2 dependence. The earth will look smaller to the observer as they move away. The thing that the delay will affect is if there is an event. If there is an explosion, the observer will not notice until the light gets to them. Events happen at particular times. But the earth just sitting there sends out the same signal continuously. Only time-tagged events will be affected by the delay.

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5 minutes ago, swansont said:

The earth doesn't "know" where an observer is. The lights leaving the earth doesn't care about any potential observers. It will spread out, decreasing in intensity with approximately a 1/r^2 dependence. The earth will look smaller to the observer as they move away. The thing that the delay will affect is if there is an event. If there is an explosion, the observer will not notice until the light gets to them. Events happen at particular times. But the earth just sitting there sends out the same signal continuously. Only time-tagged events will be affected by the delay.

I meant the Earth will look larger, because closer. And length contracted.

1 hour ago, the traveler was closer to the Earth, and the Earth was closer to the traveler.

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17 minutes ago, michel123456 said:

I meant the Earth will look larger, because closer. And length contracted.

1 hour ago, the traveler was closer to the Earth, and the Earth was closer to the traveler.

But the earth isn't closer when you are 1 LH away.  The light doesn't "remember" where it came from. 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.

In fact, almost all of this discussion could be done with examples at slow speeds, allowing us to ignore relativity completely. Then it becomes simple everyday effects, and the misconceptions based on those effects could theoretically be cleared up.

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