Every Life is on Fire

What do Moses’ encounter with the burning bush, and the theory of dissipative adaptation in non-equilibrium thermodynamics, have in common?

 

Answering a question with a question: That we understand neither?

 

Okay. So that’s my lame attempt at inventing an origin-of-life joke; if it ever goes viral in the future, you read it here first.

 

You might be surprised, however, that a serious scientist is making a connection between a religious encounter with a strange sight and the physics of complex systems. That individual would be Jeremy England in his first book Every Life is on Fire. The subtitle of the book: “How thermodynamics explains the origins of living things”.

 

I’ve enjoyed reading England’s papers, and I’ve recently mentioned and quoted one of his key papers introducing dissipative adaptation. His prose is very clear and he’s good at explaining things by providing touchstone examples to the non-physicist, even when these papers are in highly technical journals.

 

Every Life is on Fire, though, is a strange hybrid book. It’s aimed at a very general non-scientist audience. You won’t see equations, and instead you get simple sketches communicating complex physical principles in simpler lower-dimension examples. However, in addition to the science, there are short vignettes on how key events in the first two books of the Bible (Genesis and Exodus) provide analogies (or perhaps parables) to picturing the science. The cynic in me thinks this will reduce the marketability of his book. Non-religious scientists reading the introduction might cringe at what they think might be mystical mumbo-jumbo that obscures rather than illuminates. Non-scientists interested in religious and spiritual things might be disappointed a few chapters in when they find that the book focuses on the science; the connections to spirituality are tenuous and loosely allegorical at best. That’s too bad, because while there is an unevenness to the book, England overall does a good job explaining his theory of dissipative adaptation.

 

Let’s dive into the science. What is dissipative adaptation? The idea is that if one is in a situation where energy is flowing, one will adapt oneself to that energy flux in particular ways. This adaptation can be in harmony with the ‘direction’ of energy flow, as when a tree bends it shape over time given the prevailing winds. But it can also resist that flow by reducing the effects of the energy-shaping over time. In some cases, the shaping causes the incoming energy to be more favorably absorbed. In other cases, the shaping causes “holes” where response to those energy bands is minimized. England uses vibrational resonance to illustrate a number of his ideas, e.g., the shattering of a wineglass by an opera singer. He also discusses balls rolling up and down hills, springs, and escalators.

 

I particularly liked his escalator analogy. He uses it to describe how an energy source can drive a chemical reaction one-way over an activation barrier, but make it very difficult for the reverse to happen. This is not what we tell our chemistry students in college-level General Chemistry. The picture we show them has smooth a curve representing the energy “hill” that must be surpassed for a chemical reaction to take place. Imagine rolling a ball up the hill. Only if the ball has sufficient energy in its motion to overcome the activation energy will it get over the hill to the other side. If not, it rolls back down. Indiscriminate broad spectrum thermal energy (a.k.a. “heat”) is like this. The ball rolls around in its valley unless it gets enough of a kick to get over the hill.

 

But what if the source of energy had the feature of providing small kicks in a particular direction? Think of this as an escalator going up. It powers your movement in that direction so you don’t need to exert the same amount of energy climbing the stairs. Small work cycles in thermodynamics can conceivably do this under the right conditions. If you’re trapped in a deep valley surrounded by steep smooth mountains, but one direction provides a way of escape via an escalator, and all other directions would require you taking a run at the slope, what’s your most likely path out? The escalator!

 

The crux is that when you get over the hill, you slide down and there’s no escalator going back up in the reverse. So even though the activation energy is the same backwards or forwards (in the diagram), this reaction will be mostly one-way. Equilibrium thermodynamics predicts equal amounts of reactants and products over time. Non-equilibrium thermodynamics with dissipative adaptation will favor the products.

 

What does creating an escalator look like at the molecular level? This is not so clear. Mechanochemistry is a young up-and-coming field where mechanical stimulus through microwaves or some other oscillatory source at specific frequencies has opened up new types of chemistry targeting specific chemical bonds in specific chemical reactions. This is akin to the more established field of photochemistry that uses lasers or monochromatic photonics to drive specific reactions in chemistry. Resonance at specific vibrational modes is the driving force in these cases. England also mentions other clever setups involving rearrangements of particles that interact via weak forces taking on specific “organized” arrangements with an appropriate stimulus.

 

But all this clever chemistry is designed by intelligent humans with a specific target in mind. At the origin of life, things are much messier. The chemical system is a diverse hodgepodge of molecular compounds. The energy sources are less specific and more broad-ranging. In solution, where most chemistry happens, molecules are constantly tumbling about, and it’s difficult to “force” a specific orientation. This may be an argument for a key role played by solid surfaces – orienting molecules which are then subject to experiencing a particular gradient across the solid-solution interface. I’m discussing this in vague terms because we don’t quite know exactly what this would involve. In a sense, England’s book can be frustrating – we don’t know the answer or the specifics – but it also reflects the reality of what we know about such systems, which is not very much.

 

England recognizes the limitations in his theory of dissipative adaptation. He doesn’t make oversized claims, and he is careful to hedge his pronouncements. While his approach based in non-equilibrium thermodynamics and leveraging kinetics is not new, he provides a fresh way of looking at the problem with easy-to-understand analogies and examples even though the underlying reality is much more complicated, or more accurately, complex. The picture I have after reading his book is the shaping of a lump of clay by external forces. As you push the clay, it bends partly to your will absorbing the mechanical energy into its new structure. If you pressed your thumb into the clay, the imprint gives you a clue as to what took place. New external forces can cause other deformations into new structures. These might leave clues as to how the clay evolved into its present shape. Some of that “history” may have been erased or written over, but a close examination may recover other traces. I suppose that’s what we do in origin-of-life research.

 

The burning bush is a fitting analogy to England’s book and he discusses it in his final chapter. Fire, the energy source, does not consume the bush nor reduce it to ash. Rather the bush takes on larger life characteristics, or a larger-than-life character as the deity speaks through the burning bush. Those opposed to the introduction of spiritual and religious imagery into science can skip it while enjoying the rest of the book. (They can also skip the couple of pages at the end of each chapter.) But for those who are open to a more holistic view, England does a relatively good job discussing how such imagery can help the reader appreciate complexity and paradox, things that science stumbles over. He doesn’t try to infuse mysticism into every aspect (as Gerald Schroder does in The Science of God, which I find unconvincing), but instead England is thoughtful about science and spirituality. Overall though, it’s still a book about science – and it’s nice to see someone introduce non-equilibrium thermodynamics in layman’s terms and analogies. While I personally enjoyed reading it, I suspect others will find it less engaging compared to some of the best science writing out there.