Martillo talks about the twin paradox

[Tach]

May be you didn't considered the symmetry properly.

Actually , I did. Between you, Emil and OnlyMe there are enough ignorants, so you can have an entertaining discussion.

 

[przyk]

No I don't think would be good to include Doppler shifts factors on the problem. This just complicates it more. When it is said to consider what one twin would see about the other twin it means we want to take the relativistic prediction of the observation for the other twin. That's what Lorentz Transform does, it makes the necessary transformations to observe what is happening on the other frame as it would be seen directly and instantaneously by the twin "at rest".

The Lorentz transformation describes the relation between the coordinates of two inertial reference frames that are always moving with the same velocity with respect to one another in perpetuity. If the relative velocity between two observers ever changes, even instantaneously, their rest frames cannot be related by a single Lorentz transformation the whole time. In twin paradox-like scenarios you can attach "rest" frames to both the Earth and travelling twin(s) if you want, but their rest frames are not related by Lorentz transformations in that case. Accounting for the actual relation between their coordinates gets you additional effects, like gravitational time dilation associated with acceleration.

I think the symmetric linear travel avoids the problem you mention.

No, you're just describing the same scenario as the usual twin paradox, except with a third twin, which doesn't change anything. A couple of pitfalls:

two of them travels symmetrically in opposite direction far enough and stop (in relation to the twin "at rest") at the same time (the symmetry allows this)

They stop at the "same time" according to whom? Presumably you mean according to the twin "at rest". Just keep in mind this is frame-dependent in relativity.

I consider this point as the better starting of the travels to be considered. As they stopped in relation to the twin "at rest" all twins can have their clocks resinchronized again and start a symmetrical travel back for all them meet again.

That's fine, but like I said in an earlier post, once your two travelling twins start moving back to the one in the middle "at rest", they will no longer agree that their clocks are still synchronised because their standard of simultaneity/synchronisation will have changed. Only the twin "at rest" will still consider that all their clocks are synchronised immediately after the other two twins start moving back.

What matters now is what each twin would observe at any point of the travel, this means to each one consider and record the relativistic predictions of what would be happening on the other twins and their own observations in their own frame to finally compare observations at a final crossing point (I think is simpler to consider they don't reunite there but just interchange the information while travelling at the constant velocity of the travel.

Like various people have explained to you in one or two different ways, if you correctly account for the relativity of simultaneity effect/gravitational time dilation, you will find no contradiction. And like I explained earlier, that isn't surprising because what happens in noninertial reference frames, including instantaneous switching from one inertial frame to another, is derived from what happens in inertial frames. So considering the point of view of an accelerating observer can never lead to a contradiction.

 

[przyk]

In relativity any frame of observation is equivalent, right?

Wrong. Every inertial reference frame is equivalent in special relativity. Inertial reference frames always move with constant velocity with respect to one another. So if the relative velocity between two observers ever changes, at least one of them is noninertial. It is possible to handle noninertial frames if you want, but they're not equivalent to inertial frames and it is a mistake to treat them like they are.

And we can choose any frame of observation possible, right?

Yes, but you can't treat them all equally. If you use a noninertial frame, including one that you make up by stitching two partial inertial frames with different velocities together (corresponding to an observer instantaneously accelerating from one constant velocity to another), it is an error to treat it as equivalent to a single entirely inertial frame.

 

[martillo]

Like various people have explained to you in one or two different ways, if you correctly account for the relativity of simultaneity effect/gravitational time dilation, you will find no contradiction. And like I explained earlier, that isn't surprising because what happens in noninertial reference frames, including instantaneous switching from one inertial frame to another, is derived from what happens in inertial frames. So considering the point of view of an accelerating observer can never lead to a contradiction.

The symmetric twins' paradox eliminates the problem of the effect of acceleration in the problem. Both twins experience exactly the same relativistic effects, acceleration included. If we first take the frame K (non-inertial if you want) attached to one twin, make the predictions (with acceleration included or not), after consider the same situation but with the frame K attached to the other twin and make the predictions. As both experience exactly the same symmetrical physical effects both predictions must be exactly the same except that in each case we are dealing with the other twin and so opposite results are obtained.
Whatever the travel would be with whatever velocities and accelerations the physical effects on both twins are identical. This way if with one pair of frames you would find, just for instance, that one would age less then, in the other symmetric pair of frames you necessarily must find that this time the other twin would age less. No other way is possible in a perfectly symmetrical travel.
The "symmetric twins' paradox" solves it all.

 

[eram]

Huh? The fact that you are incapable of following the math doesn't mean that the answer isn't clear.

sorry, that comment was directed at martillo.

 

[Tach]

I think the symmetric linear travel avoids the problem you mention. Initially the three twins are together with clocks syncronized and two of them travels symmetrically in opposite direction far enough and stop (in relation to the twin "at rest") at the same time (the symmetry allows this). I consider this point as the better starting of the travels to be considered. As they stopped in relation to the twin "at rest" all twins can have their clocks resinchronized again and start a symmetrical travel back for all them meet again.
What matters now is what each twin would observe at any point of the travel, this means to each one consider and record the relativistic predictions of what would be happening on the other twins and their own observations in their own frame to finally compare observations at a final crossing point (I think is simpler to consider they don't reunite there but just interchange the information while travelling at the constant velocity of the travel.
I think if we make such considerations many problems are avoided and the paradox turns simpler.

There is no "paradox" in this case, the two clocks traveling towards the center clock will show exactly the same time. I am willing to bet that you, being totally ignorant of relativity , will not understand that.
You don't even need three clocks, consider only two. Synchronize them remotely. Now, let one clock move VERY SLOWLY towards the other one. When they meet, they are still synchronized. This is called the "slow clock transport synchronization method". It is well known in mainstream physics.
What happens if one of the clocks is not moved very slowly?

 

[Emil]

There is no "paradox" in this case, all three clocks show exactly the same time. I am willing to bet that you, being totally ignorant of relativity , will not understand that.

LOL
Twin1 and twin2 are those who travel. Twin 3 stay.
What is the age difference between twin1 and twin3?
That depends on twin2, if he travel or not!
LOL

 

[Tach]

LOL
Twin1 and twin2 are those who travel. Twin 3 stay.
What is the age difference between twin1 and twin3?

$$\frac{L}{v}(1-\sqrt{1-((v/c)^2})$$

That depends on twin2, if he travel or not!

Nope.

LOL

You, martillo and OnlyMe are on the same level of ignorance.

 

[martillo]

There is no "paradox" in this case, all three clocks show exactly the same time. I am willing to bet that you, being totally ignorant of relativity , will not understand that.

What a silly commment.
I can't believe I should answer this...
I am the ignorant of Relativity or you are?
Did you forget we are dealing with relativistic predictions of Lorentz transforms?
Not at all. The three clocks would show exactly the same time only before the travel or when they stop. Once the travel begins Lorentz's Transforms would apply and as one twin is travelling at some velocity relative to the other differences in the timing of each twin would appear in the relativistic predictions for each one.

You, martillo and OnlyMe are on the same level of ignorance.

Same level of ignorance or wisdom. Afterall the wisdom Socrates said "I only know that I know nothing".

 

[Tach]

I am the ignorant of Relativity or you are?

You are, years of posting the same garbage and your "book" are ample proof.

Once the travel begins Lorentz's Transforms would apply and as one twin is travelling at some velocity relative to the other differences in the timing of each twin would appear in the relativistic predictions for each one.

I'll have ranch with the word salad.

 

[eram]

All of you sound like this:

But it doesn't go into great detail, only a small section devoted to it.


in the meantime, we really should stay on topic

I'm sorry. I couldn't imagine your intention was to hear only how mainstream pretend to solve your twin's paradox. I thought you could also have interest in the "dissident" ("crank", "crackpot" or whatever) approach for which the problem actually has no solution at all because it is a real contradiction in Relativity.
I apologize for this. Sure I'll post nothing else at all.

well, if you hold "crackpot" views then discussing the twin paradox is pointless.

At the same time, the mainstream response doesn't seem to be very clear.

"Crackpot" from whom's perspective? The mainstream followers? What else could you expect...
I supposed you were a bit smarter.
Waste of time.

@martillo, take look at this QUOTECEPTION.

My orignial post was directed at brucep, cos I think he misunderstood the "we should stay on topic" part.
And I didn't call you a crackpot, you said it yourself.

Since you already hold such views, you believe relativity is false.
However, this thread is not to prove the twin paradox wrong. I'm not going to discuss that within this thread because I'm not interested in discussing that at the moment.

The mainstream claims they have the solution to the paradox, therefore I want to hear the mainstream's explanation. This thread is for that purpose.

If you keep on replying with your crankish views, then you're just bogging everyone down, cos they have to waste time explaining it to you. That's all there is to it.

 

[martillo]

All of you sound like this:

@martillo, take look at this QUOTECEPTION.

My orignial post was directed at brucep, cos I think he misunderstood the "we should stay on topic" part.
And I didn't call you a crackpot, you said it yourself.

Since you already hold such views, you believe relativity is false.
However, this thread is not to prove the twin paradox wrong. I'm not going to discuss that within this thread because I'm not interested in discussing that at the moment.

The mainstream claims they have the solution to the paradox, therefore I want to hear the mainstream's explanation. This thread is for that purpose.

If you keep on replying with your crankish views, then you're just bogging everyone down, cos they have to waste time explaining it to you. That's all there is to it.

You know, my experience in forums says threads can have very unexpected paths. I started threads going who knows where out of the initial topic of the thread. If you want to ban me or somebody else out of the thread you should try to tell that to the moderator.
I have mantained my discussion on the topic of the thread and someones showed interest in my answers (agreeing or not) and others "attacked" me so I couldn't avoid posting about.
You know, you seems newbie in forums and you can't control the threads the way you expressed you want to control. May be a moderator or administrator of the forum can explain it better to you.

 

[Tach]

"I only know that I know nothing".

Yep, you know nothing. Doesn't seem to stop you making a fool of yourself with your crackpottery.

 

[martillo]

Yep, you know nothing. Doesn't seem to stop you making a fool of yourself with your crackpottery.

I can't believe you are considered as a "Valued Senior Member" of this forum...

 

[OnlyMe]

I can't believe you are considered as a "Valued Senior Member" of this forum...

I am pretty sure that title is bestowed based on the number of posts one has made.

 

[Tach]

I am pretty sure that title is bestowed based on the number of posts one has made.

Good to see you two cranks agree.

 

[OnlyMe]

Good to see you two cranks agree.

There was nothing derogatory intended Tach. It seems I am also a Valued Senior Member.

 

[eram]

You know, my experience in forums says threads can have very unexpected paths. I started threads going who knows where out of the initial topic of the thread. If you want to ban me or somebody else out of the thread you should try to tell that to the moderator.
I have mantained my discussion on the topic of the thread and someones showed interest in my answers (agreeing or not) and others "attacked" me so I couldn't avoid posting about.
You know, you seems newbie in forums and you can't control the threads the way you expressed you want to control. May be a moderator or administrator of the forum can explain it better to you.

ok so i cant control it the way i want. But you have been repeatedly been posting on why the twin pardox is false. It could be, but today i want to hear the mainstream explanation.

You do realize that stating that the twin paradox is false is the most straightforward assumption. If you think these mainstream proponents are talking out of their ass, arguing with them wont change their minds anyway.

So you're free to post, but i hope you'll be considerate and try not to bog everyone down.

 

[przyk]

The symmetric twins' paradox eliminates the problem of the effect of acceleration in the problem.

No it doesn't, because you have the twins all synchronising their clocks when they're all stopped, and then the two travelling twins start accelerating toward one another. The problem here is that once the two travelling twins have accelerated, they will no longer consider all the clocks to be synchronised.

Lets suppose that the twins synchronise their clocks at $$t = 0$$ and the two travelling twins L (left) and R (right) instantaneously accelerate to the constant speed $$v$$. Let's look at L's perspective for example. Once L is moving at constant velocity $$v$$, he can use the normal relativistic formula $$\Delta t/\gamma$$ to work out how much each of his other twins ages and how much their clocks gain up until the time he crosses them. That's actually completely fine and there is no problem with that. The problem is that he can no longer use $$t = 0$$ as their initial times, because that synchronisation was done before he accelerated and synchronisation is defined differently in his new frame. The initial times of his other twins in his frame, immediately after accelerating, are significantly higher than $$t = 0$$, and are exactly what they need to be to ensure there is no contradiction when they all cross over and compare their clock readings.

The end result is the only result relativity is capable of predicting for this scenario: when they cross over, the two travelling twins are the same age and younger than the "rest" twin.

 

[martillo]

No it doesn't, because you have the twins all synchronising their clocks when they're all stopped, and then the two travelling twins start accelerating toward one another. The problem here is that once the two travelling twins have accelerated, they will no longer consider all the clocks to be synchronised.

Lets suppose that the twins synchronise their clocks at $$t = 0$$ and the two travelling twins L (left) and R (right) instantaneously accelerate to the constant speed $$v$$. Let's look at L's perspective for example. Once L is moving at constant velocity $$v$$, he can use the normal relativistic formula $$\Delta t/\gamma$$ to work out how much each of his other twins ages and how much their clocks gain up until the time he crosses them. That's actually completely fine and there is no problem with that. The problem is that he can no longer use $$t = 0$$ as their initial times, because that synchronisation was done before he accelerated and synchronisation is defined differently in his new frame. The initial times of his other twins in his frame, immediately after accelerating, are significantly higher than $$t = 0$$, and are exactly what they need to be to ensure there is no contradiction when they all cross over and compare their clock readings.

If I understand you properly you are assuming that there could be a problem in determining the initial instant of the clocks after the acceleration stage, am I right? But you can consider that if the travel is perfectly symmetric both clocks will read exactly the same lecture at any instant, before the acceleration, during the acceleration and after during the constant velocity travel. Forget the twin "at rest" for the moment. The travelling twins would just need to read their own clocks to know the reading of the clock of the other travelling twin. Problem solved for the travelling twins. And they both would have opposite relativistic predictions and so contradiction/inconsistency. I don't understand why you stucks in little possible "technical" issues of the problem. Further, you can even not separate stages and consider an inertial frame to apply SRT for the uniform motion. You can consider the entire travel in a non-inertial frame with acceleration included applying the full GR mathematics on it. I'm not restricting tehe problem to SRT frames only. Some people say GR is needed to solve the twins' paradox,well, just apply it to the symmetric twins' paradox. What will you obtain? As they experience exactly same physical effects during the entire travel (perfectly symmetric travels) they must have exactly the same relativistic prediction in both twins, and as for each one the other is moving then the other would age less. This means opposite results and so contradiction/inconsistency. There's no need to do the math to know this.

The end result is the only result relativity is capable of predicting for this scenario: when they cross over, the two travelling twins are the same age and younger than the "rest" twin.

That's what the twin "at rest" observe only, not what the travelling twins observe. What are the travelling twins observing at the crossing point?
I repeat again and again, the paradox appears when all the observations of all the considered twins (only the two travelling ones would be enough) in all their frames of observations are taken into account and compared. If you stay with the observation from the twin "at rest" only of course no problem arises, you are not comparing this observation with any other else!
I'm tired to explain the same keypoint again and again seeing it being ignored in the discussions. That's why I actually consider the discussions about the twins' paradox a totally waste of time. I think I will not discuss anymore, particularly now that the "owner" of the thread expressed clearly he want to hear the arguments of the defenders of Relativity only. Unbelievably, preventing an "accused" one to make his defense...
I'm tired of this.
Leaving now.