Although it’s an interesting paradox, most astrophysicists don’t think Boltzmann brains are a real possibility.
But it turns out that, since the universe is expanding, these apparent fluctuations might not be coming from the vacuum. Instead, as the universe expands, the edge of the observable universe causes thermal fluctuations to appear, much like the event horizon of a black hole gives rise to Hawking radiation. This gives the appearance of vacuum fluctuations, from our point of view. The true vacuum of space and time isn’t fluctuating, so it cannot create a Boltzmann brain.
The idea, from Caltech physicist Kimberly Boddy, and colleagues, is somewhat speculative, and it has an interesting catch. The argument that the true vacuum of the universe is stationary relies on a version of quantum theory known as the many-worlds formulation. In this view, the wave function of a quantum system doesn’t “collapse” when observed. Rather, different outcomes of the quantum system “decohere” and simply evolve along different paths. Where once the universe was a superposition of different possible outcomes, quantum decoherence creates two definite outcomes. Of course, if our minds are simply physical states within the cosmos, our minds are also split into two outcomes, each observing a particular result.
In solving the paradox of Boltzmann brains, we might have to face the reality that each of us are not as unique as we appear. The many-worlds model could also be called the many-minds model. Throughout a many-worlds universe there would be minds very like ours, each with slightly different experiences, and each having as much right to be called “us” as we do.
If naturalists cannot reduce mind to matter, they try to make matter mind. It still doesn’t make sense but it does appeal to the woo-woo market. That might save it from funding cuts.
Note: We captured this information from the Nautilus site, but when we went back later, Koberlein’s article had been replaced by rah-rah and marchin’, marchin’ orders for the March for Science. But it has the same link address. Someone there may notice and fix the problem soon.
See also: As if the multiverse wasn’t bizarre enough …meet Many Worlds
New evidence for the universe as a hologram (Koberlein)
A proposed dark matter solution makes gravity an illusion
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