Today, I would like to talk to you about a seemingly simple question, but in fact it contains profound philosophical implications: Is the earth always suspended in the universe, or has it been falling? I believe that many people may say with certainty at the beginning: "How can the earth be falling? We have been living on the earth all the time, but the earth has always been suspended in space?" Hehe, don't worry, let's dismantle this puzzle step by step.
First of all, we have to admit that we live in a flat worldview. In our daily cognition, the foot down is "down" and the head up is "up". But wait, where is there a distinction between "up and down" in the universe? Where is the boundary between "up and down" in space? In fact, the so-called "up and down" is just an artificial concept given by us. Think about it, if we look at it from another angle and compare the universe to an infinite flat mirror, on which the earth rolls and rolls, can we still distinguish what is up and what is down?
Well, since "up and down" is relative, is the earth levitating or falling? Let's think about it a little deeper. Remember the Newtonian cannon experiment, if we fired a cannonball, when the initial velocity was not large enough, the shell would fall back to the ground, but if the initial velocity was high enough, the shell would keep orbiting the earth. What does this mean? This shows that the earth, because of its mass, has a centripetal gravitational pull on the surrounding objects, as if it is "attracting" other objects.
So, what about the earth itself? Can't it escape this fate of being "attracted"? We all know that in addition to the planets, there is also a "big parent" in the solar system -- the sun. The mass of the sun is more than 300,000 times that of the earth, which is a "big man"! According to the law of gravitation, the more massive the celestial body, the stronger the gravitational attraction on the surrounding objects. Therefore, the earth has always been "attracted" by the huge gravitational pull of the sun, and is constantly falling towards the sun!
You may ask, "But the earth is revolving around the sun, why is it still falling?" Let's first understand what "space-time bending" is. The great physicist Albert Einstein proposed that mass bends in space-time, just as a ball on a stretchable film will crush the film. Because the Sun is so massive, space-time around it is severely bent, like a super crater. And the reason why the earth can revolve is actually to go around in circles in this "pit"!
In other words, the Earth seems to be orbiting, but it is actually "running" and "running" along the space-time curve around the sun. It's just that because it's so fast, it looks like it's going around in circles. In fact, the earth has been in a state of "free fall", never stopping falling in the direction of the sun. It's just that because the earth has a certain speed of motion, it doesn't fall directly on the sun. It's like when you are in the long jump, you hold an object in your hand and shake it hard, although the object does not fall directly in front of you, but in fact it also falls to the ground, but because the initial speed is too fast, it turns around you in a big circle.
Let's look at why the Earth doesn't fall directly to the Sun? The key is that the Earth orbits the Sun in an elliptical orbit. If the Earth loses its tangential velocity, it will simply fall straight in the direction of the Sun. But the fact is that the Earth, in addition to falling in the direction of the Sun's gravity, maintains a considerable tangential velocity. It is this tangential velocity that allows the Earth to continue to orbit the Sun, avoiding the fate of a direct fall. Imagine that if the earth is compared to an object that has been thrown out, the moment it is thrown out, it gains two motions: a tangential motion in the direction of the throw-out, and a centripetal motion towards the center of the earth. These two combined trajectories form an orbital line.
At this point, I believe you should have completely understood: the earth has never been suspended, it has been falling towards the sun. Not only that, but the entire solar system is in a kind of "fall". Yes, even the "big man" of the sun is attracted by the super black hole at the center of the Milky Way, and is endlessly falling there! It seems that the entire vast universe is just a game in which the "big guy" drags the "little guy" down, which is really interesting and romantic!
Through today's discussion, we not only understand the miraculous brain hole of the universe, but also appreciate the unremitting exploration and questioning spirit of scientists in the world. A seemingly simple question, with such a rich connotation and philosophy behind it, is really evocative. I hope that everyone can be like scientists, maintain the spirit of questioning, always be curious, explore the extraordinary in life, and use critical thinking to discover the joy of life. Finally, let us hope that mankind's aerospace industry can continue to take off, gallop in the vast universe, and open the door to the unknown!
Disclaimer: The information in this article comes from the Internet, which is not guaranteed to be completely correct and is for reference only.