Life is one of the universe’s great mysteries. How did it start? Where does it come from? And how common is it? These questions lie at the heart of what is is to be human and science has yet to provide answers. However a young physicist at MIT, Jeremy England, has proposed a bold new theory that says life belongs to a more general class of processes quite common in nature. It means that the origin and evolution of life follow from the fundamental laws of nature. If stated this way it sounds rather obvious, but science has yet to deliver solid proof.
Before I try to explain England’s theory, I’ll give a crash course about entropy, one the least understood concepts in physics. Some of you may know that nature strives for the point of least energy: water will flow down a stream, a ball will roll down a hill and a battery will discharge when it’s poles are connected. While this is true, nature also strives for chaos. And by chaos I mean a lack of structure or complexity. Some examples may clear this up: the milk in your coffee will mix until it’s evenly distributed, a hot object will cool down until it’s the same temperature as its surroundings and eventually a bouncing basketball will stop bouncing. Now the last example may seem odd, but it is very explicative. When the ball bounces up and down, everytime some of the energy of the ball will be transfered to the atoms of the floor, heating them up slightly and this heat will spread out over the floor. The ball will keep losing energy until it eventually has no energy left en lies still on the floor. However you will never see the opposite: the heat of the floor concentrating in one spot and flowing into the ball to let it bounce up. In the first case the energy of the ball is spread out evenly over the floor, and we say the entropy of the system (the ball and the floor) has increased, it is less orderly. In the latter case the entropy has decreased, which will de facto NEVER happen in a closed system. An open system can exchange energy and matter with its surroundings, a closed system cannot. An open system where energy is inputted can use this energy to decrease it’s entropy and hence increase it’s complexity. A living organism is such a system, for example plants take in sunlight to form complex molecules that make up their cells.
Now back to England’s theory. Based on earlier research England made a generalization of the second law of thermodynamics (which essentially states that entropy in a closed system increases) for systems that are strongly driven by an external energy source and can dump energy in their surrounding enviroment, life being a special case of this class of systems. The theory states that such systems tend to dissipate more energy over time, meaning they take up and dump more energy in their environment. Self-replication is one means to achieve this and therefore is bound to arise at some point in time. Together this might explain why life originated, however it is still a theory. If England can show that self-replication and dissipation do correlate he can prove that this theory indeed describes the organising principle that facilitates life.