A funny topic about SR

Reply Sat 28 Dec, 2019 06:22 pm
According to the length contraction effect L’ = L / γ , when the moving velocity of something trends to light speed c, the observer will see its length trends to zero. Then from the angle of light, the cosmos is moving toward it in light speed, so, the cosmos should contract to zero. That means light can reach any place of cosmos instantaneously. But in fact it seems not that situation…
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Reply Sat 28 Dec, 2019 08:12 pm
This doesn't seem like a funny question.

I could try to answer it seriously rather than make a funny remark. Do you understand how reference frames work? You need to understand how reference frames work before we can have any type of intelligent discussion about relativity.

You are asking about the "angle of light"... do you mean "frame of reference" rather than "angle"? Are you suggesting that "light" is an observer?

Reply Sat 28 Dec, 2019 09:12 pm
That means light can reach any place of cosmos instantaneously. But in fact it seems not that situation…

Just to poke your imagination.... why does it seem to you that light can't reach "any place of cosmos instantaneously"?

I would like you to explain why you made this conclusion (which doesn't seem obvious to me).
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Reply Sun 29 Dec, 2019 05:27 pm
"...from the angle of light" in the OP of course means "light" is the observer. Although it's not a man, physics rules are applicable to it too.
I don't know why you think that light can reach any place in cosmos instantaneously...Light from the sun needs about 8 minutes to reach the Earth...
Reply Sun 29 Dec, 2019 05:32 pm
I think the first problem is that you don't understand relativity. Relativity depends on a "frame of reference" ... velocities are measured differently based on different frames of reference.

You are suggesting a frame of reference in which case the cosmos would be infinitesimally short... and your "light observer" would logically be able to travel to any point of the cosmos instantaneously. What you are missing is that just because this is true in one frame of reference, doesn't mean it is true in other frames.

We have to start with basic relativity... you can't understand this at all without grasping the fundamental idea of relativity.

I will help you with this if you would like. There is one concept that is difficult for students to grasp, you have to be patient. Everyone who studies physics in college has to work through this in their second or third semester. I will help you through this if you would like.

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Reply Mon 30 Dec, 2019 01:58 am
The OP hints that 3D space is not sufficient enough to describe the motion in nature as well as Einstein's SR can be extented.
Next is explanation in X4 Theory:
Light is in the matter state of X4 = ∞
When X4 = ∞, it’s very special situation, the 4D space Gama factor Ý = 1. Then Lorentz transformation is L’ = L. That means from the view/angle of light, space does not contract. More interesting △t’ = △t, so, L’/△t’ = L/△t, namely c’ = c, It means light speed is a constant in different inertial frames.
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