Life and Self Replicator (2)

Once we think of life as an agent that performs computations, they will collect and store information about the unpredictable environment. If so, can we explain the nature of life, such as the replicating and adaptation, meaning and purpose of life, with the concept of information machines? Some physicists agree. Meaning and intention can also appear naturally in thermodynamic laws or statistical mechanics.

Maxwell's Demon and Information Machine

According to thermodynamics, the capacity to extract useful work from the energy of the universe is always decreasing. Then, the density of the heat becomes increasingly flattened. In any physical process, energy is inevitably diffused into unusable heat and becomes a random movement of molecules. The thermodynamic quantification of such randomness is called entropy. Therefore, entropy is a measure of disorder. If we use the entropy to refer to these words, we can say that the entropy of the universe is always increasing. This is the second law of thermodynamics. According to the second law of thermodynamics, the universe will eventually maintain its equilibrium in the maximized state of entropy, perhaps calling it the death of the universe.

James Clerk Maxwell conducted an thought experiment on the situation against the second law of thermodynamics. He assumed a hypothetical demon that would harpoon the second law of thermodynamics. It is often known as Maxwell's demon.

Assuming a simple assumption, let us consider an isolated room with a mixture of two gases, hot or cold, with a wall and a door in the middle, and a demon between them to send the floating particles to one side of the room selectively. In this process, the demon assumes that there is no consumption of work when opening and closing the door. Then, initially, the two gases were mixed, but over time, the two molecules are separated into hot or cold rooms, resulting in a decrease in entropy.

Illustration of Maxwell's Demon. Credit: Jason Torchinsky.

Demon needs two assumptions to accomplish this. First, the demon should have more information than we do. This is not simply a statistical averaging approach, but should be able to see all the molecules individually. And second, it should have the intention to separate the hot and the cold. If it intends to use its knowledge, it can avoid the laws of thermodynamics. However, this assumption does not necessarily violate the second law of thermodynamics. If we calculate the demon together into a system, entropy increases. This increasing entropy occurs in the processing of the information. It does not heat up in getting information and storing it, but it causes heat to erase information. This is called Landauer's principle.

If the demon's memory is infinite, the entropy can be reduced if there is no need to erase the information. To be more precise, the fact that the demon remembers something is itself treated as entropy.

Living organisms are similar to Maxwell's demon. They consume their energy in the environment of a world that can react with numerous chemicals and keep themselves in the end, eventually falling into the dwindling and equilibrium of death. The life system eventually evolved in various ways to avoid such a state of death. They acquire energy around them and maintain this inequilibrium state, which they do with their "intention". Even very simple bacteria have access to heat sources and nutrition for this purpose. In 1944, physicist Erwin Schrödinger called this feature of the life "negative entropy" in his book "What is Life?".

In this way, life can be viewed as a computational machine optimized for storing information and using useful information. And you can see that observing life actually does a really good job. Today's best-built computers will use thousands or tens of thousands of times more energy to process information than life. The life system has a guiding system to learn from experience, to store information about the surrounding environment, and to utilize it in future behaviors. And this is the gene that has developed to transmit across generations.

In next post, I will cover another typical characteristics of life "self replicating" and several trials in a name of "artificial life".


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