In classical physics, time is a constant independent of everything, independent of any external force, and always maintains a uniform and constant flow rate. Therefore, scientists at that time believed that it was impossible for human beings to escape the shackles of time, and seemingly feasible time travel could only exist in fantasy.
But with the birth of the theory of relativity, time travel, which has been labeled as "impossible" for a long time, has once again aroused scientists' thinking, because Einstein pointed out that time and space are not absolute, only the speed of light is absolute, and its speed in vacuum is constant, which is 300,000 kilometers per second.
At the same time, Einstein also pointed out that the faster an object moves, the slower it takes to act on it. When the speed of motion is infinitely close to the speed of light, its time is infinitely close to stagnation.
Using this law to travel in the future is actually very simple. Theoretically, just keep accelerating. More importantly, human astronauts are already traveling in time.
At present, the record holder for the longest stay in space is astronaut Gennady Padalka, who stayed in space for 879 days.
According to the calculation, the 879-day flight on the International Space Station made him younger than his peers on earth 1/44 seconds. In other words, if we take his peers on earth as the reference object, Padalka has actually crossed into the future after 1/44 seconds.
In fact, Padalka's speed in the universe is not very fast, only 28,000 km/h, which is not the maximum speed that human beings can create, because on the Large Hadron Collider, human beings have been able to accelerate protons to the speed of 99.438+0%, and this speed is not the limit. With better equipment, human beings can continue to improve this speed.
For observers outside the collider, the proton time accelerated to 99.995438+0% has been about 6900 times slower. To some extent, human beings are emitting subatomic particles into the future.
Of course, time travel is not the patent of astronauts in outer space, and ordinary people on earth can actually enjoy it. According to the special theory of relativity, massive celestial bodies can affect the surrounding space-time.
This means that the farther away from the surface, the faster time flows, so people who live on lower floors have slower time than those who live on higher floors. What needs to be remembered is that all this is theoretical. In fact, the time difference between the two is too small to be calculated.
However, compared with the residents at the lower level, the residents living at the upper level do enjoy the welfare of "crossing into the future" every day, although the crossing time is very small.
Using this magical physical effect, if we want to reach the earth in 1000, we can reach the earth in 30 18 as long as we fly to the place 500 light years away from the earth at a speed of 99.995% and then turn back.
Due to the time dilation effect, the spacecraft has left 1000 years for people on earth, but for people in the spacecraft, it only flew in the gorgeous universe for about 10 years.
Although this way of crossing is cool, it is impossible to operate in practice, and even this way can only exist in science fiction or science fiction movies, because there is no way for human beings to accelerate the quality of things to 99.995%.
Even the "Parker" solar probe, known as the fastest aircraft of mankind, has only reached the speed of light of 0.00067%, and there is still an insurmountable distance from 99.995%.
However, just like primitive people who ate hair and drank blood tens of thousands of years ago, they simply could not imagine that humans could land on the moon tens of thousands of years later. At the current level of human science and technology, it may not be possible to make a spaceship with a speed of 99.995%, but who knows in the future?
Over time, we may be able to visit the distant future, but it is not so easy to go back to the past, and even the difficulties we face are far greater than visiting the future.
Because of the iron law that the speed of light can't be surpassed, scientists can only find another way, from black holes, string theory, wormholes and even the theory of circulating beams, to find ways and inspiration to go back to the past and challenge the impossibility in the universe.
On June 28th, 2009, "King of the Universe" Hawking held a special party. Party invitations are sent out after the party.
Hawking believes that if human beings have the ability to go back to the past in the future, then they must know this party and will definitely come to this party.
Unfortunately, no one showed up until the end of the party. Hawking put forward several speculations about this result: First, time travel is impossible, no matter how many years of human development and how advanced technology.
Second, in the future, people will have strict control over time travel, and it is forbidden to disclose their existence for fear of disturbing the historical process. Third, mankind has no future at all, or it will be extinct without time travel technology.
The last one is also recognized by the most people, that is, for travelers, the past is like a movie being played. You can experience the details and process, but you can't change anything that has happened.
Generally speaking, crossing into the future can at least make people look forward to it and have the possibility of success, but because of the existence of the iron law of the universe that makes all scientists despair, crossing back into the past and changing history has become a luxury.
Perhaps, going back in time itself violates the basic operating law of the universe, regret cannot be made up, pain cannot be cured, and history cannot be changed. This is actually the place where you can't go back to the past and it's really desperate.