2020-10-31

Why does light travel so fast? What is the motivation?

We all know that the speed of light is the upper limit of the speed of energy and information transmission. Generally speaking, there are no things faster than the speed of light in the universe (the expansion of the universe does not count, because the two are not the same thing), the question arises Now, why is the speed of light so fast? What is its initial motivation? About this issue, the transmission of light does not actually require Power, that is to say, at the moment the photon is born, the speed is destined to be the speed of light. There is no process in which the speed gradually increases from zero. The reason is precisely because the photon does not have a rest mass, so its speed is born the speed of light. About 300,000 kilometers per second.

Since the static mass was mentioned just now, is there still a moving mass?

Yes, there is indeed motion quality. In the early development of the theory of relativity, the concept of motion quality was very widespread, so what is motion quality? To put it simply, we all know that there is a mass increase effect in special relativity, the formula is as follows The left side of the equation represents the mass of motion. The meaning of this formula is that the mass of the object varies with As the speed of motion increases, it keeps getting bigger. When the speed is infinitely close to the speed of light, the mass of the object tends to infinity, and this changing mass refers to the mass of motion (the change in mass caused by motion is very vivid). However, due to the development of the theory of relativity, Einstein himself as the representative, said that the concept of sports quality should be deleted, because later General relativity involved in the mathematical framework and physical meaning, the mass of motion is no longer necessary, and it is easy to confuse people. For example, many people naturally think that the mass of motion can reflect inertia. , But in fact only the static mass reflects the inertia. 