Space time paradox warps reality

If you can follow the logic of this thought experiment, the way Dr Greene expresses this has some interesting conclusions. It goes like this......Their are two opposing countries that finally work out how to sign a peace treaty, they decide to do it on a train, and one of the rules is that neither wants to sign it first, so they decide to have a light in the middle of the table, and when the light goes on they both sign. This happens to occur at the same time that the train goes through a station with a lot of onlookers watching. Because the train is travelling at speed, the observers on the platform realise that one of the signatories signs first because the speed at which the train is travelling means the photons, from the light in the middle of the tabe has further to travel , therefore to the observers on the platform the treaty has been violated. But too the signatories, the terms of the treaty have been complied with as "they" signed it at the same time. Now the paradox...the people on the train have a clock that reads the same time, but the people on the platform have a clock that has logged the time that the first signatory signed, and the time that the second signatory signed. When the train stops will the people on the train compare their realities. Were there two different reality outcomes, where each observers reality was different because of the time dilation? leaving part of the general populace at war because the terms of the peace treaty was violated, and others on the train quite happy because the terms were upheld. So does time dilation alter observed reality outcomes? cant seem to embed the ones with two equal signs...www.youtube.com...

a reply to: anonentity

The first value determines starting point. You probably pulled it from a playlist.

a reply to: worldstarcountry

Thanks for that...

a reply to: anonentity

That's not a good example. How big is the table? How fast is the train moving?
If you've ever seen a fast train before you'd know all the people on the plattform would see is a smear. Best case scenario some can move their heads as fast as the train and get maybe one clear frame, if both signing the treaty are in that frame there's no effect, if that table is so big they're in two different frames it's so minimal people on the plattform would need super sensitive hightech laboratory equipment to measure that super tiny time difference.
Trains don't go that fast.
It was okay for Einstein to use that as example because he came up with it around 1920 or so, didn't ad that many details and just used it for the general idea.
What Brian's doing here makes me just question his sanity. Why?

So, all these different time measurements are using atomic clocks and are accurate to the microsecond or beyond?

As a practical situation, the inaccuracies of the humans perceptions of what the blur of passing numbers, or the press of a button as in a stop watch, actually indicate at the precise moment the signatures occur makes the whole difference in the times irrelevant.

The accuracy of the observers is well short of an accurate and repeatable measurement of this event.

If they are that upset over who signs first, the treaty is irrelevant as one side will find an excuse to break it soon.

a reply to: anonentity

There is no paradox. Simultaneity is relative in a relativistic universe.

Love those literal responses above. Brilliant!

a reply to: anonentity

You kind of messed up the thought experiment a little. You needed to say one is walking from the front of the train the other from the rear and are meeting in the middle to sign. It would be impossible to say in an absolute sense that two distinct events occur at exactly the same time if those events are separated in space.

There will always be an observer that could say they happened at different times because light itself has to travel through space. Einstien covered this with RELATIVITY OF SIMULTANEITY If space separates two events then it depends on your reference frame as to the order of events.

Id argue in your scenario the only true reference frame is the people at the station. Since the train would have to decelerate to check clocks. Therefore the train is not traveling at a constant speed any observation made on the train is invalid the moment they reenter the same reference frame as the people on the station.

a reply to: dragonridr

But that's still not working, if they sign the treaty at the same table, ie the same space.
The example is just really stupid, it would maybe make sense if the two'd have to push a button at the same time and one of them is in a spaceship travelling more than 30 000 km/s.
I don't know like two countries at war both push the button for nukes at the same time, with an instant quantum entanglement mechanism, so we don't run into the difficulty of how fast the signal from the guy in the spaceship takes, he'd still be lagging a bit.

Something like that

originally posted by: moebius
a reply to: anonentity

There is no paradox. Simultaneity is relative in a relativistic universe.

The trick is, as always, that time is personal. There is no objective measurement or experience of time. It experienced by a consciousness (yours) and there isn't anything you can really do to change it because it's an inherent quality of yourself.

originally posted by: moebius
a reply to: anonentity

There is no paradox. Simultaneity is relative in a relativistic universe.

Good answer.

"Signing at the same time" means one thing in the reference frame of the train.
"Signing at the same time" means another thing in the reference frame of the ground.

So if the agreement doesn't specify which reference frame, the problem is the agreement is ambiguous for not specifying which frame. Reality is not warped, you can use a Lorentz transformation to convert one reference frame to another, they are mathematically equivalent and different aspects of the same reality.

originally posted by: dragonridr
Id argue in your scenario the only true reference frame is the people at the station. Since the train would have to decelerate to check clocks. Therefore the train is not traveling at a constant speed any observation made on the train is invalid the moment they reenter the same reference frame as the people on the station.

You can argue that, but I don't know how the people on the train use the ground clock accurately, they will be using the train clock. They would have to do a Lorentz transformation to re-interpret the clock on the train to predict what the clock on the ground would show, wouldn't they? Maybe not impossible, but tricky.

The larger point of course is this thought experiment is talking about what would be at the speed of even the fastest train on earth, incredibly small fractions of a second which you would probably need an atomic clock to measure. It's not something that someone using a stopwatch would measure at train speeds. The thought experiment is relativistic meaning these effects become more significant as the velocity approaches the speed of light, which is fast enough to circle the earth about 7 times in one second. Obviously no train goes anywhere near that fast.

originally posted by: Blue Shift

originally posted by: moebius
a reply to: anonentity

There is no paradox. Simultaneity is relative in a relativistic universe.

The trick is, as always, that time is personal. There is no objective measurement or experience of time. It experienced by a consciousness (yours) and there isn't anything you can really do to change it because it's an inherent quality of yourself.

Sounds like nonsense to say "There is no objective measurement or experience of time." Yes there is a personal perception of time. That doesn't mean there's not an objective measure of time using atomic clocks. Neither is exclusive, both can exist and don't have to agree with each other (and often they don't). In fact, some people study how much they disagree and why, ever hear the expression "a watched pot never boils"? Using personal perception, it may seem to take longer when watching it, for it to boil, if you don't use a stopwatch.
But if you use a stop watch, it should take the same time to boil every time if all other conditions are equal, (other than whether you are watching it or not, which shouldn't matter to the stopwatch time).

For example, atomic clocks can measure your head aging faster than your feet. You'll never experience that by subjective means, the time difference is too small for you to perceive without looking at an atomic clock.

You look up when you desire to be exalted, I look down because I am exalted.

a reply to: Arbitrageur

Regarding the possibility of a truly objective (i.e. spanning across frames of reference) measurement of particles that account for relativity, what is your interpretation on Heisenberg's work and the idea of the "observer effect"?

I understand (on a surface level, not deeply in terms of the math/equations) the concepts that Einstein and Heisenberg described in their theoretical work, and there was at one time unresolved differences between the two. As far as I'm aware, there was no historical reconciliation of relativity against the uncertainty principle, although I may be unaware of newer progress towards "unifying" relativity with competing models of particle physics.

originally posted by: SleeperHasAwakened
a reply to: Arbitrageur

Regarding the possibility of a truly objective (i.e. spanning across frames of reference) measurement of particles that account for relativity, what is your interpretation on Heisenberg's work and the idea of the "observer effect"?

The observer effect is often confused with the Heisenberg Uncertainty principle, it even says so in your link, but they are not the same thing. For one example, checking tire pressure is an example of an "observer effect" which has nothing to do with Heisenberg's uncertainty principle. It's hard use a tire pressure gage to measure tire pressure without a little air leaking out as the gage is applied, thus the act of measuring changes the tire pressure, but this has nothing to do with the uncertainly principle.

I understand (on a surface level, not deeply in terms of the math/equations) the concepts that Einstein and Heisenberg described in their theoretical work, and there was at one time unresolved differences between the two. As far as I'm aware, there was no historical reconciliation of relativity against the uncertainty principle, although I may be unaware of newer progress towards "unifying" relativity with competing models of particle physics.

There are some ideas for unifying relativity and quantum mechanics in some sort of quantum gravity model or other ideas, but that remains an unsolved problem.

Here's a doctoral thesis from 2017 discussing what is my understanding of the basis of your question:

Generalized Uncertainty Principle and Quantum Gravity Phenomenology

The fundamental physical description of Nature is based on two mutually incompatible theories: Quantum Mechanics andGeneral Relativity. Their unification in a theory of Quantum Gravity (QG) remains one of the main challenges of theoretical physics.

Quantum Gravity Phenomenology (QGP) studies QG effects in low-energy systems. The basis of one such phenomenological model is the Generalized Uncertainty Principle (GUP), which is a modified Heisenberg uncertainty relation and predicts a deformed canonical commutator.

In this thesis, we compute Planck-scale corrections to angular momentum eigenvalues, the hydrogen atom spectrum, the Stern–Gerlach experiment, and the Clebsch–Gordan coefficients. We then rigorously analyze the GUP-perturbed harmonic oscillator and study new coherent and squeezed states. Furthermore, we introduce a scheme for increasing the
sensitivity of optomechanical experiments for testing QG effects. Finally, we suggest future projects that may potentially test QG effects in the laboratory.

So the author has a GUP idea and also some ideas to make measurements, which are not easy to make in this respect but will ultimately be needed to convince people which model is right.

Another issue: I wouldn't assume the Copenhagen interpretation of quantum mechanics that's taught in textbooks is necessarily the right one, in fact there are probably at least as many professors who think it's wrong as who think it's right. In some interpretations there is no "wave function collapse" like there is in the Copenhagen interpretation. Don't ask me which interpretation of quantum mechanics is right; nobody knows, which was the topic I used to kick off my 400 page thread on physics questions, linked in my signature.

For example, here's what a measurement of the position of a particle may look like if one assumes the wave function collapses when the measurement is made:

Wavefunction Collapse

But what if this is not the correct interpretation, and there really is no wave function collapse? Hugh Everett thought that the wave function collapse idea was flawed because it was trying to describe a quantum mechanical system in a classical sense. But he says you can't get away from quantum mechanics so instead of wave function collapse he proposed a universal wave function, in which everything is quantum mechanical, even the measurement system that caused the collapse, so a measurement is one quantum system interacting with another. So far nobody has been clever enough to figure out a way to tell which interpretation is correct by means of lab experiment, if that's even possible.