[hamdani yusuf (OP)]

Forward and reverse time jump only appear to the accelerating observer  when the observed object is not co-located. The observed object itself isn't affected by the acceleration of the observer.

If the acceleration is less extreme, the forward time jump becomes time sprint. While the reverse time jump can turn into time rewind. At the focal point of the simultaneity lines, the accelerating twin observes a time stop. With low acceleration away, he observes a time crawl.

[Halc]

What's considered established at some point, may no longer be the case a few decades or even years later.

It doesn't matter who said that. What's important is whether it's true or not.

I completely disagree. It being true is a fairly trivial thing, but the fact that the new established theory has, without exception, only been made by those who first understood the previous established theory, means that no troll (somebody proposing anything with said understanding) has ever contributed to progress, and that was the point of the comment.  Not saying that you're a troll, but I am noticing that you use arguments that seem only used by trolls, notably the first quote above.

What's more important is whether the equations accurately represent physical reality.

The twins scenario is not representative of physical reality. The exercise is a simplified exercise in Minkowskian spacetime, and real spacetime is Minkowskian only locally. The twins scenario is not a local scenario.
This means that you need to use GR to represent non-local physical reality. The SR exercise (especially your funny diamond one) is inapplicable since the answers it gives are trivial differences compared to the differences GR would produce.

You seem to think that you know better than professional scientists working in this field, including Einstein.

The average professional scientist knows next to nothing about relativity, but their field of expertise is elsewhere. No, I never claimed to know relativity better than any student that say took a graduate level course in it. I know it well enough for my purposes, which doesn't involve actually getting a rocket to go where I want it to.

Einstein reportedly said that he "didn't recognize" his theory of special relativity anymore because of how its interpretations and applications evolved far beyond his original formulation. When he developed the theory in 1905, his focus was on solving specific physical problems, such as reconciling Maxwell's equations of electromagnetism with the principle of relativity.

However, as the theory gained widespread acceptance, it became a foundational framework for theoretical physics and was interpreted in ways Einstein had not anticipated, especially in the hands of other physicists. For instance:

1. Mathematical Formalism: Mathematicians and physicists like Hermann Minkowski reformulated special relativity in a four-dimensional spacetime framework. While this interpretation became standard, Einstein initially resisted Minkowski's geometrical approach, as it was different from his more intuitive understanding of the theory.

This is a fairly accurate response by chatgpt.  I didn't keep the entire quote. Minkowski reinterpreted his 1905 theory as spacetime geometry, not the way Einstein interpreted it in his paper. Without this new interpretation, he'd not have been abble to finish the theory (GR).  Yes, he didn't recognize it at first, but he needed to recognize it to make progress. Minkowski (his mentor) did him an extreme favor by doing this. Minkowski was given too little credit for relativity theory.  Einstein published it first, but did not do it on his own.  He had to learn a lot of mathematics along the way.

#369: time dilation is a coordinate phenomenon, differential ageing is a real world effect.

This is a super important distinction.  A physical fact cannot be explained as a function of  mental abstractions.  Time dilation is a coordinate effect. Coordinate systems are mental abstractions, and no amount of mental imaginations are going to change what physically goes on.

This diagram from Wikipedia is supposed to be the established explanation for twin paradox.

The wiki article mentions perhaps half a dozen ways to explain the twins thing, many of which are abstract.

The wiki article is a very good resource, but most of its text concerns coordinate effect (things that are true in one frame and not in others).  This includes any mention of simultaneity, distances, durations, and any numbers (coordinates) assigned to points.
Physical facts include Differential aging and any event, and also spacetime intervals.  These things are frame invariant and observer independent and are not abstractions. The twins scenario is about physical differential aging, and saying any physical fact is caused by human mental abstraction, is idealism at best, similar to saying the apple ceases to exist when not being perceived.. As I said, the wiki article is very good, and it never asserts anything like that.

The picture you reference is one of the abstractions. It shows lines of simultaneity, and simultaneity is completely abstract, having no physical meaning. That doesn't make the picture wrong, but it isn't a physical explanation.

It predicts apparent time jump in the observation by traveling twin

No it doesn't.  In fact, it doesn't mention observation at all since there are no light lines in the picture. If the twin looks at Earth when turning around, he sees the same thing just before and just after the acceleration. The observation only changes in redshift, but no time jump is observed.  What is observed would be physical fact, and nobody regardless of where they are could contest it.

Point is, learn what the diagram actually shows. It shows an abstraction, something any person anywhere at any time could compute.  All one needs to observe is an itinerary. No other observation need be made at all by anybody.  Nobody observes a time jump. The jump is just a result of a change in arbitrary selection of inertial frame, and the Lorentz transformation details such changes.  The Lorentz transform is once again purely an abstraction.

to also accept reverse time jump or rewind when the direction of the acceleration is away from the observed twin.

Yes, but again, this 'jump' is an abstraction, not anything that physically happens. One is always free to jump back and forth between two different reference frames. Acceleration isn't required at all to do it, and doing so makes zero physical difference to the universe.

    "Reverse Time Jump" --->  It sounds like you're describing something amazing, maybe time travel into the past.

Yes, it sounds kind of amazing when a coordinate effect is presented as a physical one, and this is indeed the gist of the Andromeda scenario. It's just an abstraction with no physical effect, no actual acceleration required, and no observation of any time 'jump' in either direction.

[hamdani yusuf (OP)]

No it doesn't.  In fact, it doesn't mention observation at all since there are no light lines in the picture. If the twin looks at Earth when turning around, he sees the same thing just before and just after the acceleration. The observation only changes in redshift, but no time jump is observed.  What is observed would be physical fact, and nobody regardless of where they are could contest it.

OK. I agree that this is not an observation, which should also consider light transit time. It's just a mental model of physical reality to calculate and predict the outcome. But if these time jumps are ignored, we get the wrong results.
Nevertheless, the reverse time jump is as real (or as unreal) as the forward time jump in the analysis of twin paradox using space-time diagram.

[hamdani yusuf (OP)]

Wikipedia article also describes a rotational version of the twin paradox. But in this case, the twin who experiences acceleration and deceleration ends up older than the twin stays in orbit. This is contrary to the original linear case of twin paradox.

A rotational version
Twins Bob and Alice inhabit a space station in circular orbit around a massive body in space. Bob suits up and exits the station. While Alice remains inside the station, continuing to orbit with it as before, Bob uses a rocket propulsion system to cease orbiting and hover where he was. When the station completes an orbit and returns to Bob, he rejoins Alice. Alice is now younger than Bob.[36] In addition to rotational acceleration, Bob must decelerate to become stationary and then accelerate again to match the orbital speed of the space station.
https://en.wikipedia.org/wiki/Twin_paradox#A_rotational_version

[hamdani yusuf (OP)]

Every now and then I checked if there's someone upload a reasonable effort to explain about the twin paradox worth sharing. I think this one will do.

Twin Paradox is NOT a Paradox: An Explanation that Makes Sense

Einstein's Theory of Special Relativity is confusing. It?s even harder to grasp when all the explanations disagree about how to interpret it. And to top it all off, the explanations all use a PARADOX.

I decided I needed to step in and give one more explanation to destroy the paradox once and for all. Did I succeed? Let me know in the comments what I should clarify in my next video.

Chapters:
00:00 - Intro
00:48 - The Story
03:03 - The Paradox
04:56 - The Problem
07:59 - Breaking the Symmetry
10:15 - Constructed Inertial Frames
12:27 - Video Evidence
15:21 - There is No Paradox
17:33 - Connecting the Dots

Here's an addendum to the previous video.

How to Read a Spacetime Diagram - A Crash Course

Spacetime diagrams are great tools for understanding Relativity.

This is a crash course in how to read one.

[alancalverd]

Once again, it's only a paradox if you start from classical physics and try to guess what happens in extreme circumstances.

If you start with relativistic physics there is no paradox and the answer converges to the classical result  if v << c.

Why do people waste time with this stuff?

[hamdani yusuf (OP)]

Once again, it's only a paradox if you start from classical physics and try to guess what happens in extreme circumstances.

If you start with relativistic physics there is no paradox and the answer converges to the classical result  if v << c.

Why do people waste time with this stuff?

You can't expect to find the solution if you can't see the problem in the first place.

[alancalverd]

There isn't a problem, just a common misconception that Δt = 0 for all systems, simply because it is a near-enough approximation for many purposes.

If you are brought up to believe that π = 3, you will be amazed by the "tape measure paradox". You might even become a philosopher!

[hamdani yusuf (OP)]

There isn't a problem, just a common misconception that Δt = 0 for all systems, simply because it is a near-enough approximation for many purposes.

If you are brought up to believe that π = 3, you will be amazed by the "tape measure paradox". You might even become a philosopher!

How can rejecting that Δt = 0 for all systems solve the paradox?

[alancalverd]

If you show that Δt→0 as v→0, there is no paradox, just a convenient approximation.

[hamdani yusuf (OP)]

If you show that Δt→0 as v→0, there is no paradox, just a convenient approximation.

In the case of original twin paradox, one twin travels at high a speed, significant portion of light speed, to emphasize the relativistic effects.

[alancalverd]

The "original" was not a paradox but the testable (and now demonstrated) solution to a relativistic equation. Only a philosopher could call it a paradox.

There's an old saying that a teacher explains a subject he understands, so that a child can understand it; an educationalist obfuscates a subject  he doesn't understand so that nobody else can understand it. So it is with the philosophy of science.

one twin travels at high a speed

More correctly, accelerates to a high speed. If there was relative motion at the start of the experiment, they couldn't synchronise identical clocks.

[hamdani yusuf (OP)]

The "original" was not a paradox but the testable (and now demonstrated) solution to a relativistic equation. Only a philosopher could call it a paradox.

Your statement here implies that your are trying to redefine the word paradox, or you are trying to rewrite the history of science.

[hamdani yusuf (OP)]

More correctly, accelerates to a high speed. If there was relative motion at the start of the experiment, they couldn't synchronise identical clocks.

The space time diagram as in the Wikipedia article and Minutephysics' video shows that accelerating observer doesn't observe significant time jump of the observed object when they are close to each other. The calculated time jump is only significant when they are separated in space.

[alancalverd]

Your statement here implies that your are trying to redefine the word paradox, or you are trying to rewrite the history of science.

Neither.

If I state that the world is round, G is a constant, and some atoms disintegrate, am I rewriting the history of science or merely stating a fact that wasn't obvious 2000 years ago?


Paradox:

a seemingly absurd or contradictory statement or proposition which when investigated may prove to be well founded or true:

Heavy objects fall at the same rate as light ones. Paradox or observation?

Scientific knowledge is continuously rewritten. That is the distinguishing feature of science.

I don't want to rewrite history, but I do want to teach what we know, and when we can use a convenient approximation.   

[alancalverd]

The calculated time jump is only significant when they are separated in space.

And if v_rel < ∞ that implies that significant time has elapsed since the point of synchronicity.

[hamdani yusuf (OP)]

I don't want to rewrite history, but I do want to teach what we know, and when we can use a convenient approximation.

Historically, the problem of asymmetry of time dilation between travelling clock and stationary clock was called clock paradox.

https://en.wikipedia.org/wiki/Twin_paradox#History
In 1911, Paul Langevin gave a "striking example" by describing the story of a traveler making a trip at a Lorentz factor of γ = 100 (99.995% the speed of light). The traveler remains in a projectile for one year of his time, and then reverses direction. Upon return, the traveler will find that he has aged two years, while 200 years have passed on Earth. During the trip, both the traveler and Earth keep sending signals to each other at a constant rate, which places Langevin's story among the Doppler shift versions of the twin paradox. The relativistic effects upon the signal rates are used to account for the different aging rates. The asymmetry that occurred because only the traveler underwent acceleration is used to explain why there is any difference at all,[17][18] because "any change of velocity, or any acceleration has an absolute meaning".[A 3]

Max von Laue (1911, 1913) elaborated on Langevin's explanation. Using Hermann Minkowski's spacetime formalism, Laue went on to demonstrate that the world lines of the inertially moving bodies maximize the proper time elapsed between two events. He also wrote that the asymmetric aging is completely accounted for by the fact that the astronaut twin travels in two separate frames, while the Earth twin remains in one frame, and the time of acceleration can be made arbitrarily small compared with the time of inertial motion.[A 4][A 5][A 6] Eventually, Lord Halsbury and others removed any acceleration by introducing the "three-brother" approach. The traveling twin transfers his clock reading to a third one, traveling in the opposite direction. Another way of avoiding acceleration effects is the use of the relativistic Doppler effect (see ? What it looks like: the relativistic Doppler shift below).

Neither Einstein nor Langevin considered such results to be problematic: Einstein only called it "peculiar" while Langevin presented it as a consequence of absolute acceleration.[A 7] Both men argued that, from the time differential illustrated by the story of the twins, no self-contradiction could be constructed. In other words, neither Einstein nor Langevin saw the story of the twins as constituting a challenge to the self-consistency of relativistic physics.

[hamdani yusuf (OP)]

Heavy objects fall at the same rate as light ones. Paradox or observation?

Do heavy rain drops fall at the same rate as light rain drops?

[alancalverd]

Aaaagh! The whole of Newtonian physics is debunked! Galileo really was a heretic! Bruno burns in the eternal fires of Hell!

Science is bunk, and the Pope is Infallible!

[hamdani yusuf (OP)]

The most commonly observed phenomena are usually not the simplest case, nor happened in ideal conditions.