Speaker：Yu Liu（Beijing Normal University，Zhuhai）

Time：2021-09-16 20:00:48

Location：Tencent Meeting ID：579 922 4321（No Password）

Abstract:

Since the Miller-Urey experiment 70 years ago, we have known that simple molecules and inorganic substances can generate some simple organic substances, including amino acids, through a less complex external environment. But how more complex molecules and even complex systems such as life itself emerge from simple molecules and systems are still ongoing research. There is a famous analogy: the emergence of life is like a tornado blowing through the recycling station, and those recycled parts are automatically assembled into a Boeing airplane (this probability is actually impossible, but why does life still happen). In fact, the metaphor falls into an intuitive trap: the assembly of an airplane does not begin with the smallest screw, but with modules and large parts; and life is not assembled one by one from atoms, but from simple organic matter , biological macromolecules, etc. So assembling and generating them may not be as complex as originally thought, starting with screws and atoms.

Based on this, we propose a new mathematical theory to describe this complexity; apply it to chemical molecules, and then develop the concept and algorithm of "molecular tree", which can find the intrinsic relationship between molecular structures, And organized into a tree diagram with hierarchical relationships (in addition to theoretical aspects, it can also be widely used in aspects such as designing new drugs, gene compression synthesis, etc.) (Science Advances 2021). Further research also found that what we intuitively call "complex" actually confuses two different (orthogonal) aspects: order and difficulty. For example, random sequences have low order and high difficulty (difficult to generate/reproduce), while crystals have high order and low difficulty (easier to generate/reproduce), however both cases may be called "complicated". Finally, preliminary results from further simulations show that systems satisfying this complexity description evolve naturally from simple to complex.