What causes time dilation and length contraction

This Video [Moderator's note: Unacceptable Reference removed] right here is describing a way of understanding SRs time dilation and length contraction. He tries to explain the phenomena with aether theory and argues that light does not have/is in a preferred frame of reference. So some context would be nice but in general my question is does anyone really know the physics/quantum physics behind time dilation / length contraction. I get that light has to travel two different paths at the same speed for the two different inertial observers with relative motions. Yet why is it actually happening.

Then I heard that the microscopic background radiation is in a preferred frame of reference any context to that as well would be great.

Thanks

When you measure the width of a table diagonally you find that it is longer than when you measure its width straight across. What causes that? Or what is the physics behind that?

The cosmic microwave background is a preferred frame only in the same sense as the Earth's surface frame is a preferred frame for Earthly motion or the solar system barycentric frame is preferred for solar system modelling. There's a lot of mass at rest in that frame and the maths becomes easier. But the laws of physics are the same in any other frame - so it is not a preferred frame in the sense used in relativity. Better to call it a convenient frame than a preferred one.

As Dale alludes above, length contraction and time dilation are simply aspects of Minkowski geometry, just as diagonals not being equal to widths is an aspect of Euclidean geometry. It's not particularly mysterious - it just takes a little bit of work to understand why this is an answer.

hababsbshshhs said:

TL;DR Summary: What causes time dilation/length contraction

This Video ... right here is describing a way of understanding SRs time dilation and length contraction. He tries to explain the phenomena with aether theory

I recommend, that you forget this video. The Lorentz ether-theory is not helpful. It contains a superfluous assumption of an undetectable ether.

As others mentioned, it is better if you learn about the physical meaning of the invariant 4D-spacetime-interval between events:
http://www.faculty.luther.edu/~macdonal/Interval/Interval.html

Moderator's note: Thread level changed to "I".

Dale said:

When you measure the width of a table diagonally you find that it is longer than when you measure its width straight across. What causes that? Or what is the physics behind that?

Fair enough, so that’s your response to the twin paradox? I get what you say and yet it doesn’t relay answer it. So imagine you’re near a black hole and for the rest of the universe 20 billion years pass by but for you it’s only 20 years. Now the moment you start to leave the black hole everything around you is gone so is the black hole so physically you’re the last man standing. How’s that work ?

hababsbshshhs said:

Fair enough, so that’s your response to the twin paradox? I get what you say and yet it doesn’t relay answer it.

You didn't ask about the twin paradox, you asked about length contraction and time dilation. The physics behind them is closely analogous to the physics behind a table having a different diagonal to its width - so what, to you, wuld be an acceptable answer to "why is a table longer across the diagonal than the width"?

hababsbshshhs said:

So imagine you’re near a black hole and for the rest of the universe 20 billion years pass by but for you it’s only 20 years. Now the moment you start to leave the black hole everything around you is gone so is the black hole so physically you’re the last man standing. How’s that work ?

You took a shortcut through spacetime.

You seem to be shotgunning questions on widely disparate topics. If you really want answers to them, you really need a textbook.

hababsbshshhs said:

Fair enough, so that’s your response to the twin paradox? I get what you say and yet it doesn’t relay answer it.

You can find plenty of already existing PF threads, plus a FAQ article in this subforum (at the top of the sticky threads), that discuss the twin paradox. Please read them.

hababsbshshhs said:

So imagine you’re near a black hole

You should not even be trying to think about this scenario until you have a good understanding of the simpler flat spacetime case.

hababsbshshhs said:

This Video

Because nobody is every allowed to post nonsense on the internet.

hababsbshshhs said:

a black hole

Where I fear this thread is heading.

OP. you got some answers to your question. Does this satisfy you? If so, say thank you and if you have questions on other topics, start a new thread on a new topic. If not, tossing in new questions will not help with either question.

The key is @Dale's table. Do you agree with it? Do you see its relationship to SR?

Thread closed for moderation.

After moderator review, the thread will remain closed as the OP was based on an unacceptable reference and the only substantive question posed has been answered. Thanks to all who participated.