As we all know, speed is a physical quantity representing the speed of an object. Theoretically, the speed should be infinite.
But it is described in Einstein's theory of relativity:? The speed of a massive object is limited. Its speed can be infinitely close to the speed of light, but it will never reach the speed of light? .
Why can't the speed of light exceed? The saying that the speed of light cannot be surpassed comes from Einstein's special theory of relativity. The speed of any object can only be infinitely close to the speed of light and cannot be surpassed.
It can also be understood that for an object with static mass, no matter what its mass is, it can only approach the speed of light infinitely, but it is impossible to reach the speed of light.
Why is this happening? In fact, this is in Einstein's mass-energy equation E=MC? There is a good explanation in, e represents the energy possessed by the object, m represents the mass of the object, and c represents the speed of light. It can be seen from this equation that there is a certain proportional relationship between energy and mass, and the greater the mass, the greater the energy.
Conversely, the greater the energy of an object, the greater its mass, including kinetic energy. In other words, if an object wants to reach the speed of light, the mass will become huge as the speed gets closer to the speed of light.
For example, when the spacecraft flies at 90% of the speed of light, its mass is twice that of the spacecraft when it is relatively stationary, which means that the engine must double its output to accelerate the spacecraft. So the higher the speed of the spacecraft, the higher the energy and the greater the mass. At this time, everything in the spaceship will become heavier and heavier, which is the mass increase effect.
Let's look at Newton's velocity superposition formula again. If the train travels at 4/5 times the speed of light and a person on the train walks on the train at 3/5 times the speed of light, then on the ground, the speed of the person on the train should be 4/5+3/5, that is, 8/5 times the speed of light, which is greater than the speed of light.
However, when the train travels at a speed close to the speed of light, people on board feel that everything is normal. But from the ground, it was found that the people on board were moving very slowly, so the people on board were moving forward. On the ground, it is not 3/5 times the speed of light at all, but much smaller than this speed.
At this time, all the physical and chemical changes on the train are actually very slow for people on the ground, so people on the ground should see that the final speed of people on the train should be equal to 4/5 times the speed of light plus a much less than 8/5 times the speed of light, and the total speed is still less than the speed of light!
More precisely, the transmission speed of any energy and information cannot exceed the speed of light.
The phenomenon of exceeding the speed of light. First, the expansion speed of the universe.
It is speculated that the age of our universe is 65.438+0.382 billion years, and the radius of Hubble volume has reached 46 billion light years, which means that the universe has expanded at least 46 billion light years in the past 65.438+0.382 billion years.
In this way, in the past 65.438+0.382 billion years, the average speed of expansion of the universe is at least 3.32 times that of light. It is precisely because of the superluminal expansion of the universe that the observable diameter of the universe now reaches 92 billion light years.
Second, quantum entanglement.
So-called? Quantum entanglement? It means that when two particles are entangled, no matter how far apart, one of them will do the same action without delay. So the distance is not a problem for these two entangled particles at all, and the connection mechanism between them is far faster than the speed of light.
Third, wormhole theory.
The concept of wormhole was first put forward by an Austrian physicist in 19 16, also known as Einstein? Rosen bridge refers to a strange celestial body in the universe, which is used to connect the distant time and space of the universe.
Although there is no evidence to prove the real existence of wormholes, scientists predict that wormholes will exist in the form of shortcuts between the endpoints of time and space. This shortcut is like a time tunnel, which can realize instantaneous transfer or even a passage beyond time and space.
In a word, wormholes can make two relatively distant local spaces close at once, which is far beyond the speed of light. However, at present? Wormhole theory? Just a hypothesis.
To sum up, these superluminal phenomena do not actually violate the theory of relativity. If we understand them more accurately, we can say that the fastest speed limit of light speed is for matter, not for space.
So this does not violate the definition that the speed of light cannot be surpassed. However, there are still many phenomena in the universe that we humans can't understand at present, so we can only say that there is still a lot of room for human progress at present.