If the speed of light is the ultimate speed of the universe, does it mean that human beings will be trapped in the galaxy forever?

This paper takes part in the series essay competition of “great science” of Recordunkown.

After the birth of mankind, through continuous efforts and development, gradually spread to the world. After entering the era of science and technology, relying on the power of science and technology, we have faster and faster means of transportation. Relying on the advantage of speed, we have realized our dream of traveling all over the world, and finally realized our dream of going out of the earth.


Therefore, we mean that in this world, speed is always the king. As long as you are fast enough, you can reach anywhere. Moreover, the super fast speed can also produce huge kinetic energy and great destructive power. The reason why meteorite is so powerful is that after it falls into the earth from space, the acceleration is too fast, and the impact on the ground produces huge damage and energy.

Although we know that speed is the king, when Einstein’s theory of relativity was put forward, a limit value of speed was put forward, that is the speed of light. Einstein Lu’s theory of relativity tells us that the fastest speed in the universe is the speed of light. No matter how hard you try, the speed of a mass object can only be infinitely close to the speed of light.

Perhaps in people’s cognition, the speed of light at 300000 kilometers per second is an unimaginable speed. At this speed, it only takes eight minutes for the sun’s photons to reach the earth. If the spacecraft has such a speed, it can also reach anywhere in the solar system quickly. However, when we look at the vast universe, we find that the speed of light is nothing in front of the cosmic scale, which can be said to be tortoise speed.


Take the Milky Way galaxy, which is 200000 light-years in diameter. If we travel at the speed of light, it will take at least 100000 years to get out of the galaxy. With a life span of about 100 years, this is obviously impossible. So it’s a desperate thing for humans to fly out of the galaxy at the speed of light. So some people have a pessimistic idea: if the speed of light is really the ultimate speed of the universe, does it mean that human beings will be trapped in the galaxy forever?

I believe many people will think so, but is it true? Of course not. Let’s not talk about whether there are things beyond the speed of light in the universe. Let’s take the speed of light as an example. Human beings also have hope to fly out of the galaxy. Why? Maybe many people only see the speed limit of relativity, but ignore the time expansion effect and scale contraction effect proposed by relativity.


When the speed of the object is faster and faster, the time of the object itself gradually slows down. When the speed is close to the speed of light, the time of the object is infinitely close to the stop. At this time, the time will become very slow, almost reaching the stop state. At this time, time has become meaningless and unimportant. On the other hand, as the speed of an object approaches the speed of light, time is also expanding rapidly, and the time line becomes extremely long.

For a simple example, if our spacecraft is going to a planet 100 light years away from the earth, it normally takes 100 years to fly at the speed of light. If the time remains the same, then the people in the spaceship are also normal. After 100 years, maybe many people will get old and die. However, the spaceship time at the speed of light stops. Although 100 years have passed, it is like a moment has passed for the people inside the spaceship.

Therefore, when the speed of light spacecraft reaches a planet 100 light years away, the people in the spacecraft do not feel how long it has passed, and there is no trace of years on their faces. Even if the speed of the spaceship can only be infinitely close to the speed of light, then the time of the spaceship itself will become extremely long. 100 years have passed outside, while the time of people inside the spaceship may only be a few years or even shorter.


If this is the case, it may not take long for us to go out of the Milky way with more than 100000 light-years. It may only take a few years. If it’s at the speed of light, it may take only a few days or less. Of course, this is because the time expansion and scale effect of the spacecraft itself has become extremely long. For people outside, it may have been tens of thousands of years, hundreds of thousands of years.

Therefore, there is an important concept in the theory of Relativity: “the speed of light is absolute, and space-time is relative.”. If we cross space fast enough, we are actually crossing time fast enough. We can span 10000 years of the outside world in one minute. Although the Milky way is 200000 light-years in diameter, it doesn’t have to take us 200000 years to cross that distance. As long as the spacecraft is closer to the speed of light, the coefficient of time expansion will be greater. If it’s fast enough, it’s possible for us to fly out of the galaxy in a year.


This is the possibility of flying at the speed of light. Although this is true in theory, flying at the speed of light is still too slow for human beings to explore space. It’s impossible for us to send an exploration spacecraft out of the galaxy in 200000 years. Although people inside the spacecraft don’t feel how much time has passed, 200000 years have passed for people living on earth.

200000 years may have already made things and people on the earth different, and it is still unknown whether human beings still exist. If it’s going to a distant galaxy, flying at the speed of light for millions of light years, although the people in the spaceship are still young, the earth has passed for millions of years. When the spacecraft returns to the earth, it may not be the familiar earth. So the speed of light can theoretically take us out of the Milky way and into distant galaxies, but in reality scientists don’t.

Therefore, we can say that flying at the speed of light will never be able to get out of the solar system. If you want to really cross the Milky way and get out of the Milky way, you still need the speed of the spacecraft to break through the speed of light. Can the speed in the universe exceed the speed of light? Of course, although Einstein’s theory of relativity defines that the ultimate speed of an object is the speed of light, there is another speed in the universe that far exceeds the speed of light, which is the speed of space expansion.


After the big bang, the universe has been expanding rapidly, and the speed of expansion has exceeded the speed of light, especially in the early days of the big bang, the speed of expansion of the universe is far beyond the speed of light. This is the concept of space. The speed of an object is limited to the speed of light, but the expansion speed of space has no speed limit. It can rise infinitely.

Therefore, the scientists put forward the curvilinear flight mode, which is to use the expansion effect of the space before and after the spaceship to realize the superluminal flight of the spaceship. In this mode, the spacecraft itself is immobile, and the power and speed it can move forward comes from the velocity of space-time generated by the expansion and compression of space. This is similar to the earth’s surfing, the foot of the surfboard does not move, the human body with the wave movement forward quickly.


In addition to the warp speed flight mode, scientists have also proposed the wormhole shuttle theory, which is a channel connecting two different space positions in the universe. Through it, one galaxy can quickly reach another galaxy. This speed is far faster than the speed of light, which is completely beyond our imagination.

Of course, whether it’s flying at warp speed or flying through wormholes, it’s just a guess of scientists at present. Whether they really exist and whether they can be realized in the future still needs constant exploration and research by scientists. As long as human science and technology can continue to develop and give human enough development, we believe that we will find a faster speed mode in the future. As long as we have the advantage of speed, the galaxy is nothing and the universe is nothing. We can travel all over the galaxy and the universe with the advantage of speed. We are looking forward to that day.

Guys, what do you think of this? Welcome to leave a message below to discuss and express your opinions.

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