A “Boltzmann brain” is the name for an intelligence that would randomly generate itself out of nothing. In some cosmological theories, believe it or not, the number of Boltzmann brains are thought to outnumber every human being who has ever lived or will ever live. By a long shot. Please allow me to explain this odd concept I just learned about a few days ago.
Boltzmann was an Austrian physicist, best known for the development of statistical mechanics, who proposed that the entire universe could have randomly generated itself out of nothing, even though that would be a highly improbable occurrence (to say the least). However, if the universe is thought to have existed forever, sooner or later it would have happened, was his reasoning--because even if the odds against something happening are one in one trillion or lower, given infinite time, even something unbelievably unlikely will eventually happen. Eventually--as in a trillion trillion trillion trillion years perhaps. This idea that the cosmos we know could spontaneously arise from random matter floating around in an eternal universe was based on his statistical understanding of random motion of matter and embraced the concept that matter instantly self-assembling itself in a complex form is not impossible…just highly highly highly improbable (again, to say the least). Modern cosmologists who apply Boltzmann's principle speak of quantum flux--that the vacuum of space randomly produces particles and antiparticles that usually vanish into nothing before they are even perceived to exist...usually. But in a very highly unlikely scenario, such particles could stick around and self assemble into complex forms.
Boltzmann developed this theory before the Big Bang was the commonly-accepted theory of how the universe came to be. Before the development of the Big Bang concept, the simplest way to explain how the universe could have come into existence was to imagine it had always existed in some form. Which lead to Boltzmann’s thought concerning our current cosmos, which has relatively low entropy and thus is highly mathematically improbable, but that given infinite time, this improbability really poses no problem. Sooner or later, our stars, planets, galaxies, and all else that exists would self-create based on random chance only, given enough time, instantly popping into existence in the form everything currently holds.
Or course, the Big Bang theory, after Boltzmann's time, puts a time limit on the universe…and the currently-accepted figure of 14 billion years is not nearly enough for a universe creating itself out of nothing, fully developed, to actually happen (if such a thing could ever happen at all)…
The concept of the Boltzmann brain came about when someone noticed that if we’re talking about things randomly generating themselves, wouldn’t it be easier to imagine a mind would generate itself randomly with a complete set of false memories and this mind would simply imagine there is an entire universe, as opposed to the entire universe self-generating? Because a single mind spontaneously generating itself, even with false memories, is more probable than an entire complete cosmos creating itself out of nothing. Which, in terms of probability, is certainly true.
This thinking, even though based on mathematical probability, crosses quickly into philosophical speculation as I see it. If a mind can be postulated to instantly generate itself with false memories and no prior cause, how can anyone know at this very moment that you are not a Boltzmann brain, floating somewhere in a universe that is otherwise totally empty, simply imagining everything else that exists, including your own five senses, your past history, and your interactions with other people? On a certain level it strikes me that you don’t know and you can’t know…once confronted with an idea like this, if you take Boltzmann’s well-established concept of probability and how it's been applied seriously and what that implies for self-generating minds, then that means that believing there is such a thing as a material world outside of yourself involves at least a little bit of an act of faith.
It turns out Boltzmann’s concept proves to deliver some highly inconvenient mathematics. Because in certain views of the cosmos, ones that see the universe approaching infinity in any way at all in terms of time (and space), it’s actually thought to be likely that there are Boltzmann brains self generating at a rate that eventually would cause them to infinitely outnumber all of humanity. Cosmologists know this sounds rather insane, as the linked NY Times article discusses. They know it sounds insane, but according to what I’ve read on the topic, they also know the math is valid…so they think this is a sign there is something wrong with the math, something they need to fix. (“No duh,” some of my readers are probably saying. For me, the solution to this problem is simple--the universe we inhabit is not infinite in time. It has not always existed and will not always exist in the future).
As a Christian writer deeply interested in both science and the supernatural, I see a lot of potential stories in the Boltzmann brain concept. Why couldn’t a story suggest that God is the original Boltzmann brain? Who instantly came into existence and then through a process not yet understood, brought about everything else? Perhaps by everything we know being a product of His imagination? I don’t believe at all that God is a Boltzmann brain, but it’s an interesting notion that puts a new twist on the idea of God’s existence and would be an interesting backdrop for a science fiction tale with a religious flair. And it’s certainly hard to argue from a materialistic point of view that this isn’t possible. From a strictly materialistic point of view, it most certainly is possible, assuming a universe that exists for an infinitely long time…
I know for many of my Christian friends, the subject of God as a Boltzmann brain would be taboo, but what about other uses? What if angels and demons, whose creation is never explained in the Bible, simply self-generated randomly in a universe that would allow that? God would be responsible for the universe that allowed that spontaneous generation, of course…but wouldn’t that potentially change the nature of Lucifer’s rebellion? If he’d never been directly created by God? Just maybe, anyway?
Or more simply, why shouldn’t interstellar exploration stories include some random intelligences existing in deep space? Instead of assuming non-corporeal intelligences to have evolved to a “higher plane” from planet-bound life forms as Star Trek did a number of times (particularly in the first movie), the minds in the stories I would recommend writing would prove to have come about fully formed, in a mathematically explicable process that had nothing at all to do with evolution…