Doubts about the theory of relativity, several doubts about the theory of relativity

You should note that the speed you express is based on a certain reference object (frame of reference), "B sees that A's time slows down", a clear expression is: in a frame of reference that is relatively stationary with object B, it is observed that a clock that is relatively stationary with object A (i.e., time in a frame of reference) travels a unit of time longer than a clock that is relatively stationary with a reference frame B.

At this point, you have a potential standard time of being on B, and compare the time on A to conclude that time on A is slowing down.

In the same way, the unit time of looking at object B on object A also becomes longer. At this point, your standard time becomes the time on a again.

And what you think of as "a is slow, b is also slow" must be compared with the time on the third object c (a, b is moving at a uniform speed relative to c) and the time of c has been set as the standard time.

There are only two objects here, A and B, and you can only say on one of them, that time has slowed down on the other. And you can't say "A is slowing down, B is slowing down". Unless you're standing on the third object C.

Yes, everyone looks at each other slowly, your question is the same as the twin paradox, you can see the explanation of the gods for yourself.

Here, the speed of light spacecraft just says that the speed is close to the speed of light, which is not standard, just understand.

The special theory of relativity only applies to the inertial frame of reference, the so-called inertial frame, that is, you stand in a car moving at a constant speed, and you don't know whether your car is moving without looking outside, at this time the car is an inertial frame (to be precise, no, because you should not be forced to jump up, but you will land, so you can judge that you are gravitational on the earth, and the real inertial frame such as the space station, if you jump up, it will not land), once the car accelerates or turns, you know that the car is moving without looking outside, so it is not an inertial frame. When the spacecraft is flying at a constant speed, it is determined by the special theory of relativity that time slows down. When decelerating, it is not an inertial frame, so the conclusion that time slows down does not apply, and it is necessary to analyze it using general relativity, and the result is that time becomes faster.

The first sentence is wrong, the lightspeed spaceship is impossible, so, there is no interest in watching later.

1.You are right, each level of time is made up of a separate cosmic space. The t in (x,y,z,t) is inherently a variable that represents each different time.

But this t is shared by x, y, z. Because an event has only one coordinate, and all the spatial components of a coordinate have only one temporal rate of change, the t corresponding to x, y, and z is the same, and there is no need to distinguish between them.

It is said to be the fourth dimension because it is separate from the other dimension of the three spatial dimensions (descriptive parameter).

2.How do you tell if you're at time tx, tx-1 or tx+1?

3.Faster-than-light time rewind is just a myth. Both theory and practice have proven that there is no such thing as "faster-than-light". Definition: The speed of light refers to the speed of light in a vacuum relative to the observer. Any so-called faster-than-light is a change of concept.

To be clear, what we say by "what is actual" is actually "what the observer observes". For example, sitting on a high-speed rocket and seeing the surroundings "actually thin and slower" is meaningless to observers around the rocket.

It's like if you say, "This leaf is actually green," doesn't mean anything to a red-green color blind.

So the "change", which must be "the change observed by whom", is left without the subject of observation, and all descriptions are meaningless.

1.This is just a mathematical approach, that is, in classical mechanics, space-time can also be treated as a four-dimensional space (in the sense of spatial exponentials here, Euclidean space in classical mechanics and Minkowski space in special relativity), but in classical mechanics, the dimension of time is unchanged in any frame of reference and is meaningless.

You can even think of mass and charge as the 5th dimension, and the 6th dimension together with space-time to build a 6-dimensional space, but it's not very useful.

2.This seems to have nothing to do with the theory of relativity.

3.It is impossible to speed faster than light, not to mention that 99% of science fiction movies are nonsense, and science fiction ** is somewhat rigorous.

1. Suppose there is a reference system S, so that the velocity of A and B relative to S is equal and let S be at the midpoint of AB, and the time is right before SAB starts, then in the table of S, at a certain time, AB stops at the same time and sends an optical signal to S and the other party, and S receives the signal and learns that AB stops at the same time and the pointer is the same. However, in A's opinion, when he stopped and sent the signal, he had not received the signal that B had stopped, so A thought that the two tables did not stop at the same time, so there is the following :

2. If A is used as the reference system, B's clock slows down, so it takes the longest time. The explanation is as follows: B stops and sends light signals to A and S, and A stops immediately after seeing the signal that B stops, but B has stopped for a while at this time, so A has a long time (the same is true with B as a reference frame, B thinks that it will take a long time to stop at the same time).

But in S's view, AB does not stop at the same time, but B stops first (because it receives B's signal first), so it causes A to take a long time.

This is the relativity of simultaneity, and what appears to be simultaneous in S may not be in A. In the same way, what appears to be a simultaneous occurrence in S may not be in the case of S. Therefore, when looking at this kind of problem, it is important to have a clear frame of reference.

If A is used as the frame of reference, it means that the time measured by Table A is long.

If B is used as the frame of reference, it means that B is counted as a long time.

If we use other frames of reference as frames, it means that the table that moves slowly relative to the frame of reference has a long time [relativity], which means that we should look at the problem ...... relativelyIt's not absolute that the watch is long.