China's ancient definition of the universe, space represents space, the universe represents time, and the universe is a collection of time and space. Man's concept of time comes from the change of space, the movement of the sun and the moon, the rise and fall of all things in nature, and the birth and death of life. Therefore, people use the uniqueness of the Chinese zodiac at different times to define time. So the ancients' definition of time was so flexible and magical that everyone thought it was not scientific enough, but it was in line with Einstein's theory of relativity.
Modern people's cognition of time stems from the clock and Newton's definition of time. Newton defined in "Mathematical Principles of Natural Philosophy" that time passes evenly to the future, and it is one-way absolute; Space is static, just like a frame. In fact, Newton created an ideal state, absolute time and absolute space to describe the change of motion as a frame of reference for the existence and motion of objects. Therefore, natural changes can be expressed by mathematics, which forms the basis of modern science.
Einstein said in the theory of relativity that there is no single absolute time. Time and space together constitute a four-dimensional space-time. Time, space and matter are inseparable, and * * * together constitute the basic structure of the universe. The measurement of time is directly related to the speed of the measurer and the space-time structure in which he lives. Time will slow down near a massive object (large gravitational field), and it will also slow down when it moves at high speed. If the speed reaches the speed of light, time will stand still. If it exceeds the speed of light, time will go backwards. This led to a series of imagination and arguments about time travel.
Because time and space are relative, Einstein believes that time is an illusion and death is also an illusion. So when Einstein died, he calmly left this world with an attitude beyond life and death.
In fact, there is no fundamental contradiction between the relative concept of time and space and absolute time. Absolute time is an ideal frame of reference, or a concept created by Newton, to describe the change of motion. Einstein said that time and space are relative and inseparable, which repeatedly confirmed Newton's concept of absolute time, further revealed the principle of time change, and told the world that human cognition of time is only a feeling.