The essence of time is not merely the passage of moments; it encompasses symmetry and breaking, evolution and devolution. These characteristics together form the complex notion of 'time' in our cognition. From the macro level of the universe's origin to the micro level of fundamental particles, and even to the development of humanity itself, time reveals its multidimensional nature.
On a macro cosmic scale, the Big Bang theory and inflation model unveil the breaking of time's symmetry. Approximately 20 billion years ago, the universe exploded from a singularity, undergoing a long and rapid expansion that shaped the cosmos we see today. In the microscopic realm, physicists Cronin and Fitch discovered the spontaneous breaking of time symmetry, a finding that challenged traditional physics concepts.
In human society and nature, the symmetry of time is similarly disrupted. The theory of evolution suggests that life progresses from simple forms to complex structures. The theories of Darwin and Marx further elaborate on this viewpoint, positing that human society is also in a state of continuous improvement and refinement. However, the devolution of time is equally present, as evidenced by the process of aging from youth to old age.
Time is not only a subject of inquiry for physicists but also a theme for philosophers. Einstein once proposed that time is merely a subjective 'illusion' of humanity. In reality, time possesses both objectivity and a close connection to human subjective experience. Understanding the ultimate nature of time is one of the goals pursued by scientists.
