Human beings travel back and forth to the earth at the speed of light for one year. What will happen on the earth?

If there are a pair of sisters on the earth, the elder sister takes a light-speed spaceship to outer space, spends a year on the spaceship, and returns to the earth after another year, the elder sister is still young, and the younger sister is still young. My sister on earth may have become very old, or even the entire earth may no longer exist. Is this true? #knowledgecreatorseason 5#

The reason why such strange events occur is because of the speed of light. The speed of light causes the time on the spacecraft to change. Einstein's relevant theories tell us: The speed of light can reach 300,000 kilometers per second. Assuming that the spacecraft can fly at the speed of light for one minute, it can reach 18 million kilometers. The distance from the earth to the nearest planet is about 55 million kilometers. . The fastest aerospace probe currently flying by mankind is about tens of kilometers per second, which is less than one percent of the speed of light. With the current aerospace technology of mankind, China's "Tianwen-1" Mars probe will take a long time to fly. It takes six or seven months to reach Mars. If humans achieve light-speed spacecraft flight technology, it may only take three minutes to reach Mars, and the moon closest to the earth may only take 2 seconds.

If humans travel back and forth to the earth at the speed of light for one year, it will not be as simple as just one year on the earth. According to the time loss (slow clock effect) theory in Einstein's theory of relativity: the time elapsed on the spacecraft is not equal to the same time on the earth. There is a certain time difference between the two spaces, which is why the spacecraft takes one year. The earth may have passed several decades. The second senior sister remembered the saying in Chinese mythology that one day in heaven often lasts for decades on earth. This is the truth.

Einstein’s theory of relativity also said: All objects with rest mass will not move faster than the speed of light. The sister on the spacecraft mentioned at the beginning is assumed to be infinitely close to the speed of light. , that is, if the speed of light is set in a vacuum environment, its speed will remain unchanged forever. The ideal condition supported by this theory is that the speed of light is the fastest in the universe and cannot be exceeded, and current scientific research has not found objects moving faster than the speed of light. Although time is not forgiving, and the earth is experiencing birth, old age, illness and death every day, it cannot exceed the speed of light no matter what. Therefore, even if only one year has passed on the spacecraft, the earth may have already changed. This is because in the theory of relativity, when an object moves faster, time becomes relatively slower. When the speed of the spacecraft is equal to the speed of light, there is no concept of time at all. Time at this time is relatively static, and Even if time is frozen, my sister will not grow old because time has no effect on her.

Because when my sister flies in a light-speed spacecraft, her time will be stretched infinitely in the universe, and time will become extremely slow, and she will not even feel the passage of time. The younger sister who stayed on the earth was still feeling the passage of time on the earth. After the younger sister spent a year peacefully, the younger sister may have only experienced one second in the universe.

If human flight technology reaches the speed of light, then humans can build any door in Doraemon and travel freely in the universe. Interstellar travel and immigration in science fiction movies are no longer just a dream. By then human civilization will reach a whole new level! The second senior sister thought: Maybe in the depths of the universe, some advanced civilization alien life has realized the speed of light technology and is swimming freely in the universe!