Since Galileo invented the astronomical telescope, we have known that there are many unsolved mysteries hidden behind the dark veil of the universe. Famous astronomer Martin Rees believes that due to certain limitations of the human brain, there are some mysteries in the universe that we may never be able to solve.

Just as swimming fish don't pay attention to the existence of water, humans may also be unable to penetrate the microscopic structure that supports the universe. In theory, even if a four-dimensional space is in front of humans, humans will not notice it at all. This is a certain limitation of human body structure. Here are three unsolvable ultimate secrets of the universe, and almost each of them leaves scientists helpless and desperate.

Since the establishment of quantum mechanics, the probability and randomness of quantum have always made scientists feel helpless. Can you imagine two particles separated by countless light-years, as long as the state of one changes, the other changes simultaneously? Can you imagine that a photon that originally passed through the gap in the form of a wave will be transformed into a particle form and re-pass through a gap after it is discovered that someone observes it? According to the normal human logic, everything has a sequence relationship and a causal relationship. For example, people will first feel thirsty and then go to find water to drink. This causal relationship is irreversible. But this kind of irreversibility is only irreversible in the macroscopic world and does not apply in the microscopic quantum world. That is to say, there is no so-called sequence of causal relationships in the microscopic world. Not only will there be the possibility that the result will determine the cause, but there will even be the possibility that the result and the cause will occur at the same time. Since it came out, scientists have tried to explain it with various methods and hypotheses, but none of them works.

Why can things on earth stay firmly on earth? Why can a celestial body so huge that it subverts cognition run in an orderly manner? Among the four fundamental forces discovered by human beings, all the forces act through elementary particles. Does this mean that gravity is also acted by "gravitons"? Although humans have captured the "ripples" of gravitational waves from the depths of the universe through advanced instruments, no traces of "gravitons" have been found. The physicist Freeman Dyson, who proposed the Dyson sphere theory, believes that "gravitons" may be similar to physical quantities such as temperature and pressure, and have little to do with elementary particles. Of course, it is also possible that the current theoretical framework of human beings cannot detect its existence at all. But if this is the case, then the unified theory that Einstein has been pursuing may be hidden forever in the endless darkness.

The Planck scale (time, length and mass) can be said to be a bridge between the unknown and the known. If one tried to explore the world beyond the Planck scale, it would be impossible to make meaningful measurements there. More importantly, in that mysterious world, all well-known physical theories will fail, and elusive quantum effects control everything there. Some scientists believe that the Planck scale is not the real smallest scale in the universe. It is just a limit of human technology and understanding of the universe. Once human beings can cross this limit, they may be able to discover even more astonishing sights.