The 2nd Law of Thermodynamics (whether you understand it or not) governs much of what happens in the universe. Could it be responsible for sentience? Some recent work by a collaborator of mine suggests it as a possibility.
Firstly, what on earth is entropy? In short, it’s one of the most fascinating concepts in physics. Depending on how you look at it, it’s either a measure of disorder in a system, a measure of its statistical uncertainty or as some fundamental property of a system at least as real and influential as its energy or temperature.
Let’s imagine an empty glass. The glass is a very specific arrangement of the atoms that compose it. In fact, the number of arrangements of these atoms that make up this glass is very small indeed (we don’t consider swapping atoms as a new configuration, as they are in some sense indistinguishable).
Now let’s smash the glass!
The glass is still made of the same atoms as before, but the arrangement of those atoms has changed. In fact, a broken glass can have countless different atom configurations, many many times more than the number of arrangements that make up an intact glass. In both an intuitive and rigorous sense, the amount of disorder in the system has increased. The 2nd Law of Thermodynamics tells us that things will always progress towards disorder. Glasses don’t tend to go from broken to magically intact – they go from intact to broken. This isn’t just an observation, it’s a fundamental restriction placed on the Universe.
Ah, you might say, but glasses do go from intact to broken, because human beings can have them repaired. That’s true, but we’re producing entropy of our own. We use chemical energy to move our bodies, and this process produces entropy by breaking down the chemical bonds and releasing the stored energy. We also reduce entropy by turning some of this energy into cells and organs, objects which have their own order and structure.
But, the net entropy always increases (or stays constant), it never decreases.
Now it gets interesting. If you look at the mathematics of Darwinian evolution, then the principle of natural selection (i.e. animals that are better adapted to their environment are more likely to survive and multiply, allowing favourable mutations to be ‘selected by Nature’) and the principle of least action (animals which consume the local energy most efficiently are more likely to survive better) can be rewritten in terms of the 2nd Law. Entropy can then be seen as the governing force behind the evolution of biological life forms.
Here’s where my collaborator and I went one step further. We postulate that entropy might be the most important facet behind the evolution of intelligent life as well. Think about it like this: in the neo-Darwinian model, the process of evolution is regulated not by the animals, but by their genes, the replicators that code for our physical properties. It is the interaction of these replicators both inside our bodies (as competing alleles) as well as outside (with other genes in other animals) that drive evolution forward.
Now think about our two greatest accomplishments, which we think extraterrestrials will share: culture and technology. While these are not exclusive to humans, we have developed and evolved them into highly sophisticated structures and concepts. Technology in some sense stems from “culture” (it is generally inherited and transmitted from our ancestors, modified and improved by our current generation, and then transmitted to our descendants), so let’s think about culture for a while.
If culture is transmittable in the form of memes (individual ideas or concepts which can be “transmitted”), as many people think, then we have a new type of replicator that is susceptible to some form of natural selection (some ideas are more transmittable than others, such as languages, the idea of using books and written language, the religious concepts of life after death). Then the laws of natural selection (and hence the 2nd Law and entropy) are fundamental to the growth of intelligent civilisations.
Incidentally, this also gives us a definition for intelligence. If the development of culture and technology (which we can think of as other types of replicator) is important for intelligent civilisations, then the production of these replicators is the most sensible criterion for intelligence. As we write in our article (soon to be published in the IJA):
Intelligence is the process by which replicators artiﬁcially synthesize a radically new and fundamentally
different type of replicator.
When genes (through their influence on our physical properties) created the first meme (whether it was something simple like “this thigh bone can help me hunt better” or “Furs keep me warm when it’s cold”), the first hominid became sentient. This has pretty strong implications for what makes an intelligent civilisation. If a machine (or the leviathan we now call the Internet) starts to create its own memes without our assistance, then our definition guarantees it is intelligent in its own right (are you listening Internet?). By the same token, any animal which uses tools or communicates sufficiently complex learned behaviour down the generations, then they are also intelligent.
Remember this is only a hypothesis which requires testing. Our studies have shown that any detection of civilisations by SETI will not be able to prove or disprove this hypothesis. And more philosophical work needs to be done. Perhaps our definition begs a continuous scale of intelligence to non-intelligence, rather than a simple “yes/no” answer, but I would imagine that to be a good thing.