How so? Boltzmann brains, as I understand them, are just random thermal fluctuations that happen to take the form of a thinking brain. Fluctuations on average decay at a rate determined by how frequently energy is exchanged between the degrees of freedom. By time symmetry, when they happen they develop at that rate also. There is no painstaking process of assembly, as there is for ordinary brains.
Boltzmann brains (in universes that permit them) will be overwhelmingly dominated by the least improbable of all possible methods of formation. Matter is sticky, so that once partly assembled it has a much higher probability of continuing to remain assembled especially at the very low temperatures usually envisaged.
There are far more paths for slow formation of assemblies of matter in such an environment than instant ones. To randomly assemble a trillion correct atoms in exactly the right place at the same time is much less likely than accumulating a trillion atoms in the wrong places which then migrate through any of an immense number of possible products of paths to the right places over different times.
It seems very much more likely that the modal Boltzmann brain has had essentially all of its matter in a pre-functioning state for far longer than mere geological timescales. It will almost certainly not be biological matter due to every atom contributing orders of magnitude less probability of formation. I would guess the most likely form to be some sort of dense reversible computing substrate that will operate very near absolute zero, and for a conscious brain of this type to be immensely more common in the space of thermal configurations than even one cell of familiar biological life.
How so? Boltzmann brains, as I understand them, are just random thermal fluctuations that happen to take the form of a thinking brain. Fluctuations on average decay at a rate determined by how frequently energy is exchanged between the degrees of freedom. By time symmetry, when they happen they develop at that rate also. There is no painstaking process of assembly, as there is for ordinary brains.
Boltzmann brains (in universes that permit them) will be overwhelmingly dominated by the least improbable of all possible methods of formation. Matter is sticky, so that once partly assembled it has a much higher probability of continuing to remain assembled especially at the very low temperatures usually envisaged.
There are far more paths for slow formation of assemblies of matter in such an environment than instant ones. To randomly assemble a trillion correct atoms in exactly the right place at the same time is much less likely than accumulating a trillion atoms in the wrong places which then migrate through any of an immense number of possible products of paths to the right places over different times.
It seems very much more likely that the modal Boltzmann brain has had essentially all of its matter in a pre-functioning state for far longer than mere geological timescales. It will almost certainly not be biological matter due to every atom contributing orders of magnitude less probability of formation. I would guess the most likely form to be some sort of dense reversible computing substrate that will operate very near absolute zero, and for a conscious brain of this type to be immensely more common in the space of thermal configurations than even one cell of familiar biological life.