Why is it said that the speed of light cannot be exceeded?

We know that the sun is emitting light, just like a Gatling gun, firing bullets, for the sake of analogy. We can act like the sun is firing bullets.

We know that the Earth rotates, so if you're standing on the equator, at sunrise, you're actually moving toward the sun, and at sunset, you're moving away from the sun.

If it's a bullet and you're moving towards Gatling, it's obviously moving faster relative to you, and if it's not, it's going to feel slower. Chase meets problem, xiao Ming chase xiao Hong. I think you can understand that.

So replace the bullet with a photon (which is easier to understand than light waves) and you walk towards the photon, and you see that the photon gets faster, and the photon gets slower... (Seems to make sense, but we've never heard anyone say that light is moving with respect to something. It seems... strange to say so.

In fact, the above experiment was done at the beginning of the last century, and it was found that:

The speed of light measured on both sides is the same.

The speed of light measured on both sides is the same.

The speed of light measured on both sides is the same.

Strange! Is there something wrong with the bullet metaphor? Let's switch to sound waves, because light is a wave in addition to being a particle.

In the air, put a speaker, I run with my back to the speaker, the faster I run, the slower the sound is relative to me. When I get to the speed of sound, the speed of sound stops relative to me, and every time I make a mistake, a voice will chase me and never catch up.

This experiment is very interesting, you think, the earth has been moving in the universe, if the earth as a person, the earth moves forward, the speed of light in front will be faster, the light behind will be slower, we can measure the speed of the earth relative to the universe of some absolute coordinate system, is not very exciting ！！！！ This coordinate system is called the ether for the moment. (Please make fun of it)

If you do this experiment with light, you'll find:

The speed of light relative to you doesn't change at all!

The speed of light relative to you doesn't change!

The speed of light relative to you just doesn't change!

What a dog! Something must have gone wrong with our experimental tools! In fact, that's what people thought in 1900.

Around this time, a "clerk in the Patent Office" wrote a paper.

Since you have found that the speed of light does not change, I will assume that the speed of light does not change in any reference frame of speed!

I shoot a photon, it looks to me like it's traveling at the speed of light C, you're traveling toward the photon, you're traveling at C over 2, you're seeing the speed of light C,

I see the photon go 2,000 meters, you go 1,000 meters, so how far do you see the photon go? At first I, photon, and you overlap, and at some point:

I -- -- -- -- -- -- -- -- -- -- -- -- 2000 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- - photons

I -----1000----- you --------1000-- photons

You see the photon travel 1,000 meters

c=s/t

2000÷ my time = speed of light = 1000÷ your time

For this equation to work, you have to make your time slower than my time.

Your time is slowing down!

In fact, the patent clerk used the same method, except that he assumed that your velocity was V, and that the faster the object, the slower the time. I don't want to put a formula here. You can derive this formula on your own based on the above ideas, and then compare it to the slow clock effect. It doesn't require advanced mathematics to derive this formula. Think for yourself why it is not rigorous.)

Of course, a lot of people didn't believe the "time slows down" bullshit, until the cesium atomic clock in the supersonic plane circled the Earth a few times and actually slowed down. That's the next story.

Now, why is it that the speed of light cannot be exceeded? Because experiments have shown that the speed of light measured is the same everywhere.

So we say that the speed of the bullet is relative to the muzzle, and the speed of the sound is relative to the air (medium), and only the speed of light does not need to be relative, relative to everyone is the speed of light. So you can't say the speed of light relative to somebody, there's no such thing.

So finally, who is this "Patent Office clerk"?

Have a little ~ ~ ~ ~ ~

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There's got to be someone who's good at finding loose ends. I'm just writing the simplest science. I will study it carefully when I have time and make up the loopholes!!

On maxwell and Lorentz transformations:

Maxwell derived the speed of light from electromagnetic theory. But we didn't find the speed of light relative to who. So people thought it was relative to the light source, or relative to the ether.

Lorentz transformation is probably a precursor to relativity, but it was applied to electromagnetism, and was later generalized to the general case. (What happens in one frame (x,y,z,t), in the other frame is (x1,y1, Z1, T1) and the Lorentz transformation is the relationship between them.)

Some of the FAQ

Q: This example is actually inaccurate. I started with light at the same time because the speed of light is always greater than my speed, so I saw the whole journey from the start of my vision until the light reached the end point of 2000 meters. Even if I reached the end point of 1000 meters, I still saw the light and I still walked 2000 meters.

A: To answer A question first, why is it called relativity? Relativity says that there is no absolute inertial frame of reference, that is, every object moving uniformly in A straight line can declare itself to be at rest while other frames of reference are in motion. For each such frame of reference, any physical formula holds, and each frame measures the same amount of light.

Relativity also says, "It is impossible, by physical measurement, to find a frame of absolute rest."

For example, in my mind, I'm still, AND I say you're moving. In the same way, you have the right to claim that you are still and I am moving backwards.

In your question, when you analyze the speed of light, you're actually analyzing me as an absolute rest coordinate, the speed of light.

Q: What if the light goes in other directions?

Q: Why not distance reduction?

A: Yes, the shortening of distance and the slowing of time happen simultaneously.

Asking this question shows that you have understood and thought about it carefully. I don't have a simple explanation for these two problems, so here's the "complicated explanation" for you.

The proofs of special relativity go something like this :(the following references to me and you refer to the above examples

1. First, modify the axiom according to the experimental phenomenon "the change of the speed of light cannot be measured" : under any inertial reference frame (that is, the reference frame of static or uniform linear motion), any physical experiment can get the same result. Delete "time is the same for any frame of reference" and replace with "the speed of light is the same for any frame of reference".

2. Derivation simultaneity no longer holds that the speed of light is the same for any frame of reference. That is to say what happens simultaneously in one frame of reference does not happen simultaneously in another. (To further explain, for example, in the example above where you and I exercise, things that happen simultaneously under my measurements might happen sequentially under your measurements. This paragraph is difficult to understand and prone to habitual confusion and has little to do with the subsequent proof, so it can be ignored for the moment.

3. Relativity proves that the shortening of distance does not occur in the direction of vertical motion. For example, if you are on the ground moving away from me, this step proves that our measurements of the height at which an event occurred (like the height of a firecracker explosion) agree.

4, design you run forward, the photon runs up, I do not move the experiment (because you and I move back and forth, according to (3), the length measured up is the same). So T prime is equal to T over 1 minus v squared over c squared to the 1/2. (The algorithm I gave you can't derive this formula.) I'm just speaking metaphorically...

5. Design the experiment in which you, I and photons all run forward, and obtain the formula of shortening distance according to (4).

6. According to the above formula, assuming that the forces measured in the two coordinate systems are equal, (I am not sure about this, it is actually done by collision experiment), the mass increase formula is obtained.

7. According to the mass increase formula, the mass energy equation E= MC ² is derived.

It's just special relativity, and general relativity revises the axiom that "in any frame of reference, you do any physical experiment and you get the same result." You get rid of inertia. So the acceleration of gravity and the acceleration of motion are equivalent -- I haven't understood this part of the nonsense, and the general theory of relativity is beginning to be understood, so just forget it.

Q: In the case of me and you, you measured the displacement of the light from me, so the displacement of the light is still 2000.

A: To answer A question first, why is the theory of relativity called relativity? Relativity says that there is no absolute inertial frame of reference, so every object moving uniformly in A straight line can declare itself to be at rest while something else is in motion. For each of these reference frames, any physical experiment holds, including an experiment to measure the speed of light.

Relativity also says, "It is impossible, by physical measurement, to find a frame of absolute rest."

For example, in my mind, I'm still, AND I say you're moving. In the same way, you have the right to claim that you are still and I am moving backwards.

In your question, when you analyze the speed of light, you're actually analyzing me as an absolute rest coordinate, the speed of light.