Boltzmann Brains
Friday, January 17
A pair of tweets from Richard Ngo:
Imagine viscerally identifying with all the Boltzmann brain copies of yourself. Trillions of versions of you taking each trillionfold action for the sake of the tiny fraction who will persist - willingly sacrificing their only moments of existence to benefit the surviving you.
Everything you do is the coordinated output of a vast symphony of superimposed selves whose plans stretch across multiverses. Act like it!
This probably doesn’t make much sense without familiarity of Boltzmann Brains, so a quick refresher:
Imagine air molecules bouncing around a room. Their position is random, and thus at any given moment, their distribution is almost certainly uniform. But on an infinite timeline, anything that can happen will happen, including the unlikely configuration where all the air molecules conglomerate, for a split second, on one side of the room, or into the shape of a perfect sphere in the center of the room.
This may be similar to how the universe will look after its heat death. Quantum fluctuations in an infinitely long-lasting universe will allow brief patterns to emerge from an otherwise mostly-uniform and mostly-boring canvas.
In fact, if we take the “infinitely long-lasting” part seriously, all possible patterns must emerge. Including patterns that recreate a brain like yours, with your exact sensory input, experiencing (or hallucinating?) a world like the one you are currently in, if only for a split second.
But a split second is enough. Because of the infinite time horizon part, we need only wait another immeasurably large period of time, and the next split second will take place. From our perspective — as the consciousness embodied by the brain(s) — it will have felt like no time at all.
For this to be possible, it only requires reality to have some noisy pattern of information, like TV static or quantum fluctuations, lasting forever in an otherwise empty universe. This feels more plausible than the highly particular universe we believe ourselves to live in.
And, if it is so likely, who is to say that this isn’t the way we experience the world right now — not as a real body in a real, persistent world, but instead as a string of Boltzmann brain snapshots in a sea of noise, separated by vast, immeasurable gaps in time?
The thought used to scare me, and it still does in some ways, but Ngo’s perspective here helps. I’m not a mere string of Boltzmann brains, but instead a vast symphony of superimposed selves. I should be grateful for them.