Enter the four-dimensional space to realize crossing
In the time and space we live in, there are many spaces with different dimensions. Einstein once put forward the viewpoint of 1 1 dimensional space, thinking that human beings are only in three-dimensional space. And scientists have been eagerly looking for the secrets of four-dimensional space and five-dimensional space. This is because scientists think that the four-dimensional space may not have the concept of time, while the five-dimensional space may not have the concept of space, which shows that if human beings enter the four-dimensional space, they can travel freely through the past and the future!
Scientists are eager to leave three-dimensional space.
Of course, although we can achieve crossing, we still face a problem. If humans go back to the past, we can't make any changes to the past, because it will affect the future development, and maybe we will no longer exist. In this case, it is not necessarily a good thing to be able to travel freely through time and space. Then why are scientists in such a hurry to leave three-dimensional space?
In fact, this is because scientists think they can grasp the scale. Because people's life is too short, only a few decades, so that many things they want to do don't have enough time to finish. Don't say whether human beings can develop on the earth in the next thousands, tens of thousands or even billions of years, that is, what will happen on the earth in only 100 and 200 years? In fact, there is no way for human beings to make a complete prediction, and they can only give a reasonable guess according to the current development!
But if humans can travel through the past and the future at will, the outcome will be different! For example, before the earthquake, tsunami and other major disasters come, we can accurately cross the "pre-judgment" and take measures such as evacuation to avoid personal and property safety violations. Think of it this way, do you think it is also "fragrant" to find multi-dimensional space crossing?
In fact, in the 1980s, physicists were desperate to unify the four basic forces of the universe (gravity, strong interaction, weak interaction and electromagnetic force) into a single comprehensive force. They first tried to develop the so-called supergravity, but they had to give up because of a large number of inconsistent research results and unconfirmed predictions. Another emerging theory is string theory.
This theory was born in 1970s, but before 1980s, it was basically ignored. In 1980s, this theory became popular again, and physicists began to study it seriously. String theory is still one of the best guesses for us to fully understand the universe, but according to this theory, the universe exists in 26 dimensions! Therefore, it is strange that scientists only touch on four of them-the three interchangeable dimensions of space and the time dimension discovered a century ago.
This absurdity has been puzzling philosophers and later physicists. They are too curious to accept the reality without doubt, and they want to know why it is like this. However, a recent paper published in the European Physics Express seems to reveal why our universe may only exist in four-dimensional space.
If you look far enough away, the dimension doesn't exist. Dimensions appear only when we observe an object at close range. Seen from a considerable distance, a piece of paper looks one-dimensional. However, as we get closer, these four aspects will gradually appear in front of us. Now, when we get closer, we will find the third dimension: depth.
It is a bit difficult to think of the fourth dimension, but as scientists dig deeper and deeper, new or higher dimensions will appear. Like onions, dimensions are multi-layered. There is an obvious assumption that all dimensions prevailed in an instant after the Big Bang, but for some reason, the universe then decided to expand only the first four dimensions. Physicists suspect that other dimensions are curved and coiled in singularity space!
Then why only four dimensions? The second law of thermodynamics prohibits the expansion of other dimensions, which is the basic law of the universe. The nascent universe is full of radiation and Helmholtz free energy density (thermodynamic quantities that exert pressure on space).
Just a few seconds after the Big Bang, with the instantaneous cooling of the universe, the Helmholtz density reached its maximum, and the universe immediately "froze". At this stage, the universe once existed in every dimension we thought existed, but now it is only limited to four of them. The only way for our universe to expand to more dimensions is if it exists above the critical temperature, which is a hellish temperature, and it will certainly cool down in just one second after its creation.
The physicist's discovery is similar to the phase transition of water. The only way to change a piece of ice into liquid water is to heat it. Although this theory has not been paid attention to until recently, the principle that makes scientists turn to solve this dilemma is the anthropic principle.
According to the anthropic principle, if there are any differences in the universe, intelligent species that question its structure will not exist.
The second law of thermodynamics mainly explains why time only moves in one direction, which scientists call "forward". The law predicts that the direction of time in the universe is the same as that of disorder. However, this reasoning is incomplete.
Just as entropy seems to be increasing, time is also increasing, because the universe is still in the expansion stage, which is conducive to the germination of intelligent life. We only experience the universe in four-dimensional space, because only the prevalence of four-dimensional space is conducive to the beginning and maintenance of intelligent life.
If the universe is two-dimensional, living things will not move around. The complicated way of food digestion and decomposition or blood circulation in the body is impossible in a two-dimensional human body. Then, put forward and study why there are four intelligent species in the universe, and they don't exist at all.
In fact, life itself, even the simplest life, will be extinct, because the earth will not be able to revolve around the sun. When the distance between two objects is doubled, the intensity of gravity is reduced by four times, but it is reduced by five times in five-dimensional space and six times in six-dimensional space. In the higher-dimensional universe, the earth may not be able to orbit the sun stably, so living things will freeze to death.
Perhaps the gravitational compression and gas expansion that form the sun will be different in higher dimensions and how they happen in four-dimensional space. Maybe the sun itself will collapse into a black hole prematurely. Even atoms of higher dimensions will not aggregate to form complex molecules, which will lead to complex life.
Scientists are eager to enter four-dimensional space, which can solve the long-term mystery of our species. This is also very enlightening for physicists, because it represents a great leap for human beings to seek the unification of the four basic forces, and ultimately represents human understanding of how the universe was born, how it developed and how it might go.
First of all, scientists are not as eager to enter the four-dimensional space-time as the subject said, because we live in the four-dimensional space-time.
Einstein founded the theory of relativity, which unified time and space, and one-dimensional time and three-dimensional space became continuous four-dimensional space-time. Then, if there is one more dimension, for example, the spatial dimension is one dimension higher, what will the five-dimensional space-time universe look like? Or what will four-dimensional space look like?
At present, no one knows what four-dimensional space looks like, and even the existence of high-dimensional space is not clear. But in theory, the fourth dimension can exist, and we can infer what the five-dimensional space-time should look like through low-dimensional analogy.
A point without size is a zero-dimensional space, a straight line composed of countless points is a one-dimensional space, a plane composed of countless straight lines is a two-dimensional space, a three-dimensional space composed of countless planes is a three-dimensional space, and so on, a super body composed of countless three-dimensional spaces is a four-dimensional space. Compared with the three-dimensional space, in addition to the three dimensions of length, width and height, there is a fourth dimension that we cannot perceive.
So, if four-dimensional space exists, what will life be like? What will happen if humans enter such a high-dimensional space?
Four-dimensional space, you can refer to Klein bottle. Unlike the bottle in the three-dimensional space, Klein bottle has no concept of inside and outside, because the fourth-dimensional space connects the "inside" and "outside" in the three-dimensional biological field of vision. If there is a fly, it can fly directly from the "outside" to the "inside" of Klein bottle, and it can cross the fourth dimension without going through the bottle.
However, three-dimensional creatures like humans may not survive in four-dimensional space. Because as a three-dimensional creature, its body structure is only three-dimensional, and its body has no support in the fourth dimension, so its interior will be directly exposed through the fourth dimension, so it cannot survive normally.
If there are four-dimensional creatures, they can directly see the inside of three-dimensional space through the fourth dimension. If someone is in a closed room, four-dimensional creatures can directly transfer the people in the room to the outside of the room through the fourth dimension, without going through the doors, windows or other passages in the room, which is very incredible for us in three-dimensional space.
As shown in the above picture, imagine that we can directly transfer the two-dimensional creatures in the circle (if they exist) outside the circle through the third dimension.
In addition, because of the extra dimension, high-dimensional creatures can directly see the process from birth to death, and what happens in four-dimensional space-time is actually the evolution of three-dimensional space on one-dimensional time axis. What we see at every moment in three-dimensional space can be said to be a three-dimensional "profile" of things at every moment in four-dimensional space.
According to M theory, the space-time dimension in the universe reaches 1 1 dimension, but we can only perceive four of them, and the other seven dimensions are highly curled, so we can't perceive them. However, this is only theoretical speculation, and there is no experimental evidence yet.