Time passes more slowly for people who live on the first floor than those who live on the top floor, although it is not enough to make people inside live longer. If you want to make a person younger, you just need to travel around the world by ordinary plane. These are two incredible results, and the time effect is the same for everyone: time can be extended or shortened, depending on space, gravity and speed. This paper will lead readers to explore the seemingly close but mysterious time scale.
What time is it?
1000 years, people have been looking for the answer to this question. For example, in ancient Greece, the definition of time troubled philosophers more than mathematicians. After Galileo's great discovery, Newton finally defined time as a mathematical quantity. However, the great British scientist believed that time is an object covered with mystery, because time is independent of any object and absolutely above everything else. Time is so close to saints that God is compared to a clock.
Einstein believes that time is not like a "free dog" in nature at all, but a real measure. Even today, we still can't define time like doing anything practical. We can measure time, but we don't know what time is. We also hang "time" on the wall or wear it on our wrists. According to Einstein's theory of relativity, we know that time can be extended or shortened. This is why physicists simply use time as a series of events and mark them with time. Such as a person's birthday or the shelf life of food.
2. Does time flow like a river or is it intermittent?
Unfortunately, no theory or experiment can prove that time flows in a continuous way, or it gives people a continuous impression like every frame in a movie, that is, there is intermittent continuity. The study of the continuity or discontinuity of time also involves another question, that is, whether time has a beginning. So far, there is no clear answer. Because the famous big bang theory thinks that space-time has a beginning; Other scientists have pointed out that the scale of "time" has no instantaneous beginning, which is unnecessary. This complicates things. Because according to the principle of quantum mechanics, the time interval less than so-called Planck time is unpredictable. Planck's unit of time is of the order of seconds. So it is impossible to calculate the new state of the universe in a very short time. In short, according to the current theory, the first cry about the universe is always unknown.
Now let's return to the "continuity" of time. Strangely, it can flow continuously or intermittently, but the smallest and computable time interval is the same as Planck time. In a word, time is a continuous belt, and physicists regard it as an interlocking and discontinuous necklace.
A few years ago, scientist David Finkelstein put forward a theory, but it didn't get much support in the scientific community. The physicist assumes that time atoms exist. These time atoms may show their discontinuity.
Does time pass in the same way for all people?
Einstein's theory shows that the answer isno. In fact, like space, time is relative. What does relative mean? That is to say, in order to describe an event completely rather than vaguely, it should be placed in a frame of reference. For example, I date one person at the end of the road, and that "end" may be just the beginning of the road for another person. If I add "in the square behind the end of the road", then this "dating event" is accurate. The same is true of things with time factors. If I say that 10 years have passed, then I must point out that 10 years have passed relative to which frame of reference. Obviously, there is no need to stick to details in daily life. But who knows if we will organize interstellar travel or communicate with aliens in the future? At that time, the time interval will no longer be so simple, and we will feel the relativity of time.
A famous example can explain all this. Alpha and Beta are 30-year-old twin brothers, both astronauts. In 2000, Beta began to take a spaceship with a speed of 240,000 kilometers per second to a planet 8 light years away from the Earth. At this rate, it will take 10 years for Beta to go back and forth. In fact, in order to achieve the desired average speed, β needs to accelerate and decelerate when it reaches its destination. Because their reference frames are no longer the same, we can separate the time of α and β by changing the direction of motion. In 2020, when Beta returns to Earth, he will see Alpha celebrate his 50th birthday (20 years older), and it has just passed 12 years for himself, and he is only 42 years old. This is not an intelligence test. The expansion of time has been measured by a real watch. 197 1 year, two physicists, J.C. Hafele of Washington University and Richard Keating of the U.S. Naval Observatory, traveled around the world and measured four atomic clocks on the plane. The speed of an airplane cannot be compared with the speed of light (by millions of times). However, scientists confirmed that they captured the elasticity of time: at the end of the trip, the clock on the plane indicated 59 nanoseconds later than the clock on the ground. In addition, height also affects the passage of time. Einstein's theory shows that the closer time is to the ground, the slower time passes. In fact, in the basement, time passes slower than on the top floor of the building. It has been calculated that if you live on the first floor, you can live one microsecond longer. Of course, this is too insignificant for longevity.
If time is a measure, why can't it go forward and backward as in space?
Crossing the future and the past is science fiction. As Kurt Godel, an Austrian mathematician, proved in 1949, travel in the past was not prohibited by the laws of physics, but the conditions were very special: the universe should be able to rotate (which is impossible in reality), and the pursuers of time must move at a speed greater than 7 1% of the speed of light. In short, the menu is available, but there are no ingredients. As physicist Stephen Hawking thinks, this may be a way for nature to protect itself. Preventing time travel will avoid possible paradoxes, such as meeting yourself or changing history.
5. Is a black hole really a time machine?
One possibility offered by black holes is to fall into a time tunnel and reappear in the past. What is a tunnel? There are all kinds of hypotheses, from anti-gravity to reflecting the world, to the replacement of the universe. Although there are many hypotheses, none of them are feasible. Just think about the super gravity of a black hole: time is like a rubber band, which is finally stretched. In this case, it is hopeless to get out alive. Time is a permanent topic, and people are still exploring and trying other methods.
References:
Science World Journal