Book Review: What is Life? by Erwin Schrödinger

How is life influenced by the laws of physics? This question was put forward by Erwin Schrödinger in his book What is Life?. Finding out the interconnection, or rather, the influence of physics as the fundamental laws in nature towards biological processes is his main goal in this book.

He starts the conversation by stating that every organism is significantly bigger than atoms. This leads to the idea that the physics that influences the life of organisms is largely based on statistical physics, while quantum mechanics interaction is negligible. One other supporting argument for  this is quantum mechanics, with its randomness, is unlikely to influence organisms because we did not see living organisms randomly change all the time. 

However, the discovery of chromosomes cancelled out the idea that quantum mechanics interaction can be totally neglected in living matters. With such small size, chromosomes must have been influenced by the laws of quantum mechanics. So how does chromosome stay permanent? More importantly, is it necessary for chromosomes to stay permanent? It is indeed necessary for a chromosome to stay stable and permanent to ensure the consistent growth of an organism through two different mechanisms. First, through mitosis where a cell divides and duplicates to create a perfect copy of itself including its pair of chromosomes. Second, through meiosis where a cell divides itself and only brings with them one part of chromosomes and gets ready for fertilisation.

Chromosomes as the blueprint of living matters that are being passed throughout generations, change, vary, and evolve. The variations can come from small, slow, and continuous variations due to natural selection or from mutation due to quantum mechanics. Mutation happens due to quantum jumps in the gene molecule triggered by X-rays or due to random jumps in quantum mechanics. The popular idea that the slow and small variations are inherited is wrong and mutation is actually the variations that will be inherited through generations.

So how do chromosomes stay permanent despite being in the size that can be influenced by quantum mechanics and situated in the hot environment inside the body of living matter? One possible reason is that it takes a lot of excitation energy to change the structure of the current gene to the next structure with a different energy state. It is known from the theory of quantum mechanics that to bring one system from a particular energy state to the next the system requires energy that is higher than the next energy state.

The notion that chromosomes should be treated as molecules (Delbrück's model) and thus follow the law of quantum mechanics raise a debate between biologists. Erwin, as the supporter of quantum mechanics theory, said that quantum mechanics is the fundamental theory of all atoms in nature and there is no alternative to explain the physics that govern chromosome molecules. The adversaries of the quantum mechanics theory argue by throwing such a question "Are there no other endurable structures composed of atoms except molecules? For example a gold coin buried in a tomb for a thousand years, preserving the traits of the portrait stamped on it." The answer to this question is that the underlying mechanism between molecules and a gold coin is actually similar. Both gold coins, chromosomes, and crystals are solid states that are bonded by Heitler-London bondage and it requires a lot of excitation energy to change the structures of these solids. He also brought the idea that the molecule inside the cells is aperiodic solid which is different from periodic solid with repeatable structure that is commonly found in the inanimate object. Due to reasons above, we can conclude that Delbrück's model stands the test and can be used in further considerations.

The order that is observed in the gene is different from the order-from-disorder which is observed in a macroscopic level such as a drop of milk in the water which is diluted and creates a seemingly "ordered" system that comes from the disorder of all the involving water and milk molecules. The order in living matter comes from the molecules in the gene which govern the life of the living matter. This gene molecule is in itself is in order, stable, and unbothered by randomness that happens in the quantum mechanical environment. The possible reason for this maintained orderliness, which causes living matter to evade going into the state of disorder (death), is by consuming negative entropy from the environment.

Living matter is unmatched by anything inanimate in its degree of orderliness by evading the random and unpredictable mechanism of the quantum mechanics world. The stability of the gene is so prominent and unprecedented that it is as if this matter is purely mechanical and unbothered by randomness in nature. In a normal matter such as in a chemical reaction, we can never deterministically know which atom will undergo a reaction first. The regularity of normal matters is only observable in the macroscopic view of the system. In biology a single, tiny group of atoms which govern the process and life of the living matter is seemingly governed by a different mechanism which neglects the randomness and unpredictability that occurs at the atomic level. Nevertheless, this orderliness and seemingly a purely mechanical system is not entirely new to physics as we can reflect (approximately) from the motion of planets around the sun and the motion of a good pendulum clock which is not impacted by heat and statistical mechanics. These systems work as if they are situated in the absolute zero temperature where the impact of statistical physics is non-existent. In this case living matters resemble the situation of a clockwork which is strong enough to withstand heat motion and quantum mechanics phenomenon.

In conclusion, Erwin Schrödinger argued that living matter, and chromosomes in general, is indeed influenced and governed by the law of quantum mechanics. However, the stability of the gene is so prominent and unprecedented that it is as if this matter is purely mechanical and unbothered by randomness in nature. This astonishing mechanism led Erwin to question whether a new law of physics is necessary to explain the orderliness of genes.