In the first post in this series, I described examples of systems, some natural and some human-made,1 where a few simple pieces, along with a few simple rules for how they interact, can create so many possible combinations that they could not all be explored in the lifetime of the universe. The number of bits of information required to describe their possibility spaces, and number of bits required to describe all possible pathways which connect one point in that space to another, is greater than the number of atoms in the visible universe. But the information required to describe merely possible combinations is somewhat abstract and theoretical. Let’s talk about how some of that information “gets real.”
Imagine programming many computers to play chess against each other continuously, recording every move of every game. Before long, the amount of information required to describe every game ever played exceeds the amount of information required to program the computers in the first place. How does that happen?
Each time a computer chooses one chess move out of a list of possible moves, real information is created which is recorded in the arrangements of real atoms, on paper or in magnetic memory. There are occasions in a game of chess when there is only one legal move. On those occasions, it could be argued that no new information is generated (even if the move is recorded in memory). But most of the time, there are multiple legal moves. If the computer randomly selects from all legal moves (or even from a shorter list of all moves which are more-or-less equally good), that is a contingent event. Each time a contingent event happens, real information is created. During each game, out of the huge space of all possible chess games, one real pathway is chosen, and information about those choices is recorded in real physical objects.
Something similar happens in natural systems like DNA. Imagine a population of bacteria all cloned from a single cell, all with identical genomes. Let that population live and reproduce for many generations. Any time a mutation occurs in one cell and that mutation gets passed on, the genetic diversity of the population increases. A portion of the population moves from one point in the space of all possible genomes to another point, and the amount of information required to describe the entire population increases. Mutations are contingent historical events. Each time such a random event occurs, real information about that event is stored in the DNA of the bacteria.
Random events can accumulate to turn simple, uniform environments into highly variable environments requiring a lot of information to describe. This is illustrated by a screen-saver computer program I wrote about 20 years ago. It was inspired by how atoms in solution move randomly and interact with each other. The program starts with a blank screen and it has rules which cause single-digit numbers to pop on and off the screen with various probabilities. Each time the screen updates, these atoms can move one step in any direction. Meanwhile other rules govern how neighboring atoms can bind together into molecules or how bound molecules can break apart. After several thousand updates, the screen is filled with many different atoms and molecules (see picture). Each time the program runs, the final arrangement is different and for any given run, the arrangement of atoms and molecules on the screen at the end stores some of the information of the random events that occurred while the program ran.
One of my favorite examples of how random events create this type of information is the astrophysical and geological history of the Earth. Shortly after the Big Bang, the universe was a fairly uniform place, a mixture of particles and energy almost at thermal equilibrium. One piece of the universe looked very much like every other piece, with only slight differences. Over the next 9 billion years, that changed dramatically. Consider the variety of things the universe contained by the time the early Earth had formed: all the atoms in the periodic table, galaxies, neutron stars, black holes, etc. as well as planets like ours which included water, atmosphere, land, and collections of small organic molecules. Even before life started on Earth, the universe as a whole and our planet in particular had become highly variable environment requiring huge amounts of information to describe. All that variation had been produced over 9 billion years as fundamental particles interacted with each other according to the natural law and random events that God designed.
Random events not only cause environments to become more variable over time, but also sometimes cause ever-more complex objects to self-assemble within those environments. Astrophysics and chemistry again provide examples. Under the right conditions, particles combine to form atoms. Atoms combine to form simple molecules. Simple molecules can combine to form more complex molecules. Each new assembly has unique properties unlike its component pieces.
In order for complex things to self-assemble out of simpler components, several things must be in place. First, there needs to be a steady input of orderly energy (such as sunlight). Second, something must cause the pieces to move about randomly and encounter each other in a variety of ways (such as thermal energy). Third, the pieces themselves must have the right properties so that, when they encounter each other in just the right way, with neither too much nor too little energy, they remain stuck together in new combinations.
My screen-saver computer program was designed this way. Notice the ring of atoms numbered one to eight near the center of the screen. That ring molecule has two properties which make it unlike any other molecules that the program can produce. First, the bonds are 100% stable and will never break apart. Second, it invariably rotates one notch clockwise per screen cycle. (All other molecules sometimes rotate clockwise, sometimes counter-clockwise, sometimes not at all.) But there are no “special rules” governing that particular molecule. Its two unique properties—its perfect stability and its reliable rotation—are emergent properties of the same rules that govern all other atoms and molecules. Whenever I run that screen-saver program, I have the option to assemble that molecule “by hand” at any point while it is running, but I don’t need to. Ring molecules self-assemble over time, typically within about 30,000 screen cycles.
This program provides a nice example of the importance of fine-tuning the fundamental laws. If I decrease all molecular bond strengths too much, smaller molecules tend to break apart before that ring molecule can self-organize. If I increase bond strengths too much, much large molecules take over the screen. Unless I have molecular bonds strengths tuned within a fairly narrow range, the probability of ring molecules self-organizing in the lifetime of the computer becomes vanishingly small.
Another man-made example of self-assembly is this set of plastic pieces with embedded magnets which, when put into a jar and shaken, self-assembles into a spherical construct. This sphere was inspired by how the protein coats of viruses self-assemble. For self-assembly to happen, the individual pieces must be crafted properly, with pieces of the right shapes and magnets neither too weak nor too strong, and the amount of shaking must be neither too small nor too great. This is yet another example of the importance of fine-tuning.
Under the right conditions, larger molecules can self-assemble out of smaller pieces.
What about first life? Under the conditions of the early Earth, could molecules self-assemble into ever more complex combinations leading all the way to groups of molecules which could self-replicate? That’s a very difficult question, and for now, scientists don’t know the answer. Research groups are working on that question using a variety of techniques. For now, I just want to point to one computer model which I found interesting.2 It’s a computer model of the evolution of an autocatalytic set of chemicals.3 They weren’t modeling real chemicals, but theoretical chemicals where each was described by how it up-regulates or down-regulates reactions between other pairs of chemicals. They allowed the chemicals in their model to react for a while, occasionally washing out chemicals which had already been mostly consumed by other chemicals and washing in new ones. Each time they ran the simulation, eventually, one sub-set of chemicals would become autocatalytic, increasing their own numbers by consuming other chemicals in the system. While this model doesn’t prove that abiogenesis happened this way on the early Earth, it does provide yet other model of complex systems with novel properties self-organizing out of simpler pieces.
While scientists do not yet know the probability of abiogenesis happening on the early earth, the point here is that information is no barrier. First, the possibility space of all possible combinations of fundamental particles is vastly greater than the information content of a living cell. Second, random events in the history of the universe turned some of that potential information into real information embodied in real molecules and real conditions on the pre-biotic (before-life) Earth. Third, the amount of information needed to describe the environment of the pre-biotic Earth as a whole was much greater than the amount of information needed to describe the first living organism. Fourth, on the early Earth there was a steady stream of orderly energy (sunlight) and a constant thermal jostling and mixing of the molecules. These are exactly the sorts of conditions which enable the creation of information needed to self-organize real, complex objects.