From the expansion of the Universe to the motions of the tiniest subatomic particles, modernday physics can help us interpret a dizzying number of natural phenomena. But can it explain perhaps the biggest mystery of them all: how did life as we know it begin?
Dr Jeremy England, assistant professor of physics at the Massachusetts Institute of Technology (MIT), thinks it can. He is currently working on a bold theory that hopes to reveal how lifelike behaviours could emerge from an inert collection of chemicals. “I was always interested in how the physics of big, messy assemblies of particles becomes lifelike, ever since I was doing research on protein folding as an undergraduate,” England says. “It was the way I could successfully refuse to choose between theoretical physics and biology, which both were fascinating to me.”
England’s work is based on the well-established physics of thermodynamics – the science that describes how heat moves from place to place and is crucial for many natural processes. He calls his theory ‘dissipative adaptation’, as it aims to describe how structures emerge and change through the dissipation of energy, primarily heat, into their environment. This process increases the entropy (the amount of disorder) in the surroundings, which Austrian quantum physicist Erwin Schrödinger identified as necessary for living organisms to function. Crucially, the increase in entropy makes it possible for the evolving structures to stay in what is known as a ‘non-equilibrium state’. Usually a system (which could mean anything from a box of gas to a complex structure) comes into equilibrium with its environment.
This means that there is no net flow of heat between the system and its surroundings. For example, if you leave a cup of hot tea on the table, it will eventually reach the same temperature as the room, much to the chagrin of the tea-lover who was looking forward to a cuppa. But living things are in a non-equilibrium state, taking energy from sources such as sunlight and food and pushing that energy out – ‘dissipating’ it – into their surroundings. This enables a living organism to reduce its own entropy, so it can grow and build structure. And it is the physics of such non-equilibrium states that England and his team investigate, by using computer simulations to look for situations where life-like behaviours emerge spontaneously.
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