1

Physics, Astronomy & Cosmology / Re: Which twin is older when they meet again?

« on: 16/04/2020 23:11:06 »

what is the position of the front of the train car for x=0.2598cs and t=2.3s in the train frame coordinates?

I didn't do any calculations to 4 digits of precision.  The yellow lines show lines of simultaneity along the changing frame of the train as it turns around.  You can see the line from that event being simultaneous with the short duration at t'=4 x'=0 measured at the front of the train.

The Triplets challenge - is the right triplet going to say that the left triplet proper time is the same as his/her (the right triplet)?

Proper time is frame independent, so all observers will agree that the proper times of the left and right worldlines between events A and B are identical.

If the proper time is not the same then the middle triplet reference frame analysis is useless, essentially, we do not have physics.
If the left triplet proper time is observed/analyzed as to be same as the proper time of the right triplet from the right triplet frame then we need to see those claims/analysis because according to MCF (momentarily co-moving inertial reference frame) the left frame is moving and the Lorentz Transformation does not allow for the proper time to be the same.

Maybe you should not only read, but actually comprehend that book you linked.

The claim is:
- if the left time is not the same from the right frame point of view ... then we do not have physics because it contradicts the middle triplet's frame.
- if the left time is the same as the right frame time ... then we do not have the Lorentz Transformation, we do not have the Relativity

Have fun justifying these claims.

Halc,
using this: http://www.trell.org/div/minkowski.html


The time on the train car is 4.15s'.
The train starts to decelerate at 2.3s according to your calculations.
The front of the train car is already past the turning point for the platform 2.3s.
What are you trying to show us with your spacetime diagram?
Jano

2

Physics, Astronomy & Cosmology / Re: Which twin is older when they meet again?

« on: 03/04/2020 14:52:12 »

https://en.wikipedia.org/wiki/Relativistic_Doppler_effect#Relativistic_longitudinal_Doppler_effect

Hafele-Keating experiment is a mystery, very unreliable,
Jano

...

Can you provide a link to the source?

Yusuf,
here it is:



Link at the bottom of that page: http://handle.dtic.mil/100.2/ADA489971   is currently broken.
I have a copy of the pdf though. If you want one, just send me a pm and we can coordinate,
Jano

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Physics, Astronomy & Cosmology / Re: Which twin is older when they meet again?

« on: 03/04/2020 04:06:46 »

Hafele-Keating experiment is a mystery, very unreliable,
Jano

4

Physics, Astronomy & Cosmology / Re: Which twin is older when they meet again?

« on: 01/04/2020 23:39:05 »

Well, you really should watch the video.
The time dilation has nothing to do with acceleration. It is a claim made in the video.
Why would the author made such a claim?
Because there are experiments that prove that.
I am not sure why you are talking about the acceleration?
Jano

You've either misunderstood the video or the video is wrong. Acceleration is how you change frames. The one that changes frames is always the younger once they're back in the same frame again. Without that distinction how could a different amount of time possibly pass for each? It's probably just poorly explained in the video, it usually is.

From here: http://math.ucr.edu/home/baez/physics/Relativity/SR/clock.html

The clock postulate generalises this to say that even when the moving clock accelerates, the ratio of the rate of our clocks compared to its rate is still the above quantity.  That is, this ratio depends only on v, and does not depend on any derivatives of v, such as acceleration.  So this says that an accelerating clock will count out its time in such a way that at any one moment, its timing has slowed by a factor (γ) that depends only on its current speed; its acceleration has no effect at all.

Although the clock postulate is just that, a postulate, it has been verified experimentally up to extraordinarily high accelerations, as much as 1018 g in fact (see the FAQ What is the experimental basis of Special Relativity?).

This is the basis for the video claim,
Jano

5

Physics, Astronomy & Cosmology / Re: How can we reach temperatures sufficient for fusion without melting everything?

« on: 04/07/2018 02:13:06 »

These guys know some stuff about plasma:

... and many things mentioned in this thread are questionable. Big time!

1hr 25min ... towards the end of the video, you can see some plasma there.
1hr 26min ... double layers, very interesting.

Anybody interested in plasma should watch the video.
This is one way how plasma can be done, without big budget like Wendelstein 7-X: https://en.wikipedia.org/wiki/Wendelstein_7-X