Considering how common life is on this planet, it’s surprising that no one can come up with a single definition of what it is. We know it when we see it, but the living world can usually provide an exception to any simple rule. One definition has to do with maintaining a non-equilibrium situation, and using that situation to build complex molecular factories that can reproduce themselves and evolve. Life is something that can control the speed at which energy flows through its system, manipulating the stream to maintain itself. Nothing that is in equilibrium can be alive. And this means that the concept of disequilibrium is fundamental to two of the great mysteries of our time. How did life start? And is there life anywhere else in the universe?
Scientists currently think that life may have started in deep-sea vents, 3.7 billion years ago. Inside the vents was warm alkaline water. Outside was cooler, slightly acid ocean water. As they mixed, at the surface of the vent, equilibrium was reached. It seems that early life may have started by standing in the middle of that path to equilibrium, and acting as a gatekeeper. The flow toward equilibrium was diverted to build the first biological molecules. That first tollgate may then have evolved into a cell membrane, the city wall around each cell that separates inside, where there is life, from outside, where there isn’t. The first cell was successful because it could hold back equilibrium, and that was the gateway to the beautiful complexity of our living world. The same is probably true for other worlds.
It seems highly likely that life does exist elsewhere in the universe. There are so many stars, with so many planets, and so many different conditions, that however freaky the conditions needed to form life are, they will have happened in other places. But the chances of that life telling us that it’s there by sending us a radio signal are small. Quite apart from anything else, space is so large that by the time any signal reaches us, the civilization that created it would probably be long extinct. However, it may be that the mere existence of life could be broadcasting signals out into the cosmos, completely unintentionally. On the summit of Mauna Kea in Hawaii there is a pair of telescope domes, matching giant white spheres parked next to each other on a ridge. My first thought when I saw them was that they were like giant frog’s eyes peering out into the cosmos. This is the Keck Observatory, and it may be these giant eyeballs that see the first hints of life outside our solar system. As alien worlds pass across the front of the distant stars that they orbit, starlight shines through the atmosphere, and those gases leave a fingerprint on the light. The Keck telescopes are starting to pick up those fingerprints, and soon they may be able to detect atmospheres that are not in equilibrium. Too much oxygen to be sustainable, too much methane . . . these could betray the existence of life down on the planet, altering the balance of its world as it strains away from the jaws of equilibrium. We may never know for certain. But that may be the closest we ever come to knowing that there are other organisms out there: the evidence of something controlling the speed of the march to equilibrium, as it builds living complexities that we will never see.
* This behavior is called “shear-thinning” and it’s handy for snails, as we’ll see shortly.
? Of course, there is a third option: that the snail had been an egg or a juvenile hiding inside the compost. But it was pretty large, and I couldn’t imagine it growing so big in such a short time.
? There’s a genuinely funny bit in Frost’s paper when he describes what happened when they accidentally set the treadmill to a very low speed. It’s not often that I’d quote a scientific paper for comic effect, but in this case it’s absolutely justified: “After completing the filming of a particular bird, the treadmill was inadvertently turned to a very slow setting instead of completely off as intended. After a short time we noticed that the bird’s head was slowly and progressively pushed forward until it eventually toppled over. Further observations indicated that toppling, or extreme changes in posture, could also be produced by very slow forward (opposite direction to that eliciting normal walking) treadmill movements. It appeared that the extremely slow (imperceptible to us) speed of the treadmill was not sufficient to induce walking in the bird, but was sufficient to stabilize its head even though this sometimes resulted in loss of equilibrium.”
§ When I first moved to the American southwest, I couldn’t shake off a nagging curiosity about exactly where all the water came from in this dry environment. The book that answered many of my questions (and tells the fascinating story of the battles over water supply in that area) is Cadillac Desert by Marc Reisner, and I highly recommend it. California is suffering from a severe drought as I write this, and the tough decisions about how to deal with it cannot be delayed any longer.
? There is actually another solution: Start drinking cappuccino. Having a foam layer on top dampens down the oscillations a lot, so foam-covered drinks don’t slosh as easily. This is also useful in the pub. Beer snobs may not like too much of a head, but at least it stops them from spilling their drink.
# There are also two smaller pendulums that help with this, just below the main one.
CHAPTER 5
Making Waves
WHEN YOU GO to the beach, it’s almost impossible to stand for any length of time with your back to the sea. It feels wrong, both because you’re missing out on the grandeur of the sight and also because facing the other way stops you from keeping an eye on what the ocean might be up to. And it’s oddly reassuring to watch the boundary between sea and land as it constantly renews and remodels itself. When I lived in La Jolla, California, my reward after a long day was to wander down to the ocean, sit on a rock, and watch the waves as the sun went down. Just three hundred feet off shore, the waves were long and low, difficult to see. As they rolled toward the shore they’d get steeper and more obvious until they finally broke on the beach. I could sit and watch the endless supply of new waves for hours.
A wave is something that we all recognize, but waves can be hard to describe. The ones at the seashore are processions of ridges, a wiggly shape in the water surface that is traveling from over there to over here. We can measure them by looking at the distance between successive wave peaks and the height of the peaks themselves. A water wave can be as tiny as the ripples you make when you blow on your tea to cool it, or bigger than a ship.