Previously on the Fermi Paradox ⇡

In 2020, we presented a handful of possible solutions to the Fermi Paradox, all characterized by a level of contrivance, as well as being terrifying. Yet, we concluded, there isn't much else to work with.

For those who don't know what the Fermi Paradox is, here is a one paragraph explanation, expressed in a way that relevant to this discussion: the universe offers an unbelievably large number of places for intelligent life forms to evolve, but keeps the chance of it very small at each place. Simple probability theory tells us that the number of intelligent life forms in the universe should be either zero or very high, but almost certainly not one. However, both of these options are impossible, zero is refuted by our existence, and a huge number is refuted by the fact that advanced civilizations must be visible from afar, but we don't see any.

If this explanation seems rushed or unmotivated, please do read the original article, in which it is explained in more depth.

Our observations indicate that intelligent life is either a one off, or at least so rare that we expect perhaps a handful in the entire universe. And it is only possible, argues the 2020 essay, and of course many other people, if the universe works by radically different rules than we understand. Scary rules, mostly.

In this essay, we present a deflationary solution to the Paradox, which requires no cosmic horrors, just some easy to accept axioms. Still weird though.

Axioms ⇡

1. The Anthropic Principle. When asking why some physical law or constant is what it is, one possible answer is that the rules of the universe must be such that we, as observers, can exist in it. Any universe that for some reason can't produce complex life forms cannot be our universe, as we wouldn't be here to see. Any universe that is too sparse for example to have clumps of matter, or doesn't have mechanisms to form atoms, molecules, or other structures might be possible in theory, and might even exist somewhere, but ours can not be such. This provides a sort of "lower bound" on what kinds of worlds can exist.

2. The Axiom of Least Improbability. Toss a hundred coins, and keep the result if the first ten is all heads, try again otherwise. The expectation is that the rest of the coins will have a regular distribution, not all heads, like the first ten. Another way of thinking of it: create a large number of worlds at random. You would expect simple ones, with low entropy, to be more numerous. Highly improbable ones, with high entropy, should be proportionally rarer. If you are placed in any one of them at random, you would expect yourself to end up with more probable universes. This provides a sort of "upper bound" on what kinds of worlds can exist with any realistic probability.

Neither of the axioms are obvious and both are subjects to criticism. However, even those that disagree will admit these are not outrageous claims. If such axioms can adequately explain the Fermi Paradox, isn't it an excellent argument on their side?

N=1 ⇡

At a glance, our universe doesn't seem to obey the Least Improbability principle. We only need a single planet to live on, yet we have countless galaxies with countless stars in each, an excess of unimaginable proportions. However, there is a counterargument to this. What if we can create a simple ruleset that results in a slim slim probability to create intelligent life at a particular location, but we give it many locations to try? In a way, it doesn't matter if you toss a coin a thousand times, or toss a thousand coins at once.

In fact, an argument can be made that it is easier. Consider for example a fractal, like the Mandelbrot set. Most functions of its kind will be boring, and their behavior will be proportionally complex to their construction. But there are these outliers, like the Mandelbrot set, which generate a remarkably complex landscape from a remarkably simple setup. If you pick images at random, you will never get the complexity of such a fractal. But pick functions at random, you will hit the jackpot in a reasonable time.

What we see in our universe is a lot of "code reuse", the same laws of physics contributing to complexity in more than one way. Gravity keeps mass together, enabling stars that create energy-dense regions around them. The same stars produce heavy elements, which eventually gets ejected. The same stars, again, form neutron stars, which then collide to create even heavier elements. You need generations of star formation to get all together: energy, proximity, and complex atoms.

Our puny brains have made strides in understanding the laws of this universe, which frankly indicates that the laws are not that complicated. Yet, they describe a world the complexity of which we can't even hope to comprehend. We have good reasons to believe that the best way to complexity is a particularly lucky set of generator rules.

Which one is more likely? A random world that is just complex enough to have us in it, or a random ruleset combined with a sandbox just big enough to come up with us eventually? The universe we observe can easily be this optimum: simple but sufficiently big.

This would kill two birds with one stone. Three, actually. It explains why we see nobody around. It explains why the universe is so wastefully big. And it also explains why the rules of physics are approachable to our hunter-gatherer brains.

Consequences ⇡

So what does this mean to us? There are good news and bad news.

The good news is that there are no crazy entities playing with us, and there is no doom lurking around the corner. We do live in a world that is pretty much what it looks like: matter and physics. And a lot of space to discover.

The bad news is that there probably isn't a lot to discover. Or rather, what is there is not too interesting, just more of the same. The rings of Saturn, the might of a black hole, stellar neighborhoods so dense the sky glows, and similar spectacles may worth a few million years of travel. But then they get old quickly.

The only spectacle in the world that has the capacity not to get stale is us. The universe was selected so we can observe it. Yet, at the end, it falls upon us to create our own entertainment, our own adventure, and our own meaning.