Current models of physics do not rule out Boltzmann brains, but don’t really support them either. Even the slightest variations in our expectation of the long-run future of the universe make them either essentially impossible, or possible but vanishingly rare. In no scenario are they anything like common.
The main ingredient in any Boltzmann brain scenario is staggeringly large quantities of time in which nothing else happens except random thermal fluctuations. None of this tiny little trillion year nonsense, we’re talking about a number of years that is so large that it would take you many trillions of years to even read the number. Obviously we do not have, and can not have, any support for that actually happening.
On the timescales being discussed here, whether or not all matter becomes iron is irrelevant. Even if an iron atom has a 10^-1000 chance of encountering a ridiculously unlikely random gamma ray photon that spallates it into lighter elements, over these timescales that happens so many times that you can’t hope to keep track of them all even if you had some entropy-proof enormous computer. It even happens to trillions of atoms in close proximity simultaneously so many times that you can’t hope to keep track of how many times it happened. I cannot state strongly enough how mindbogglingly long these periods of time are. Immortal monkeys eventually typing at random the complete works of Shakespeare have nothing on these lengths of time; they packed up their typewriters with the job well done long before the first Boltzmann bacterium. Then unimaginably many Boltzmann bacteria would have to form and decay before the first instance of a Boltzmann bacterium that was one atom larger, and so on until you get enough atoms to form an actual brain.
Predicting the future is hard. Being confident in predicting the future is foolhardy. Confidence in the existence of Boltzmann brains requires an immensely precise prediction about how reality must proceed over unimaginable timescales in the future, far beyond any conditions that we have observed or even could possibly hope to observe, and is empty intellectual arrogance of the greatest order.
Thanks for the long answer, the only thing I did not understand is the fact of the irrelevance of the iron matter, I thought that maybe if the matter decays with iron tunneling, a boltzmann brain or other things can no longer form
Over long enough timescales any interaction will reverse, and happen again, and so on. It’s just a question of what fraction of time is occupied in each state. Or so the theory goes, at least.
Yes, there is no proof that they cannot possibly happen. It is a thing that theoretically could happen in a sufficiently boring universe, and there is no way to know whether our universe is sufficiently boring (but my prior odds are very much against it).
Current models of physics do not rule out Boltzmann brains, but don’t really support them either. Even the slightest variations in our expectation of the long-run future of the universe make them either essentially impossible, or possible but vanishingly rare. In no scenario are they anything like common.
The main ingredient in any Boltzmann brain scenario is staggeringly large quantities of time in which nothing else happens except random thermal fluctuations. None of this tiny little trillion year nonsense, we’re talking about a number of years that is so large that it would take you many trillions of years to even read the number. Obviously we do not have, and can not have, any support for that actually happening.
On the timescales being discussed here, whether or not all matter becomes iron is irrelevant. Even if an iron atom has a 10^-1000 chance of encountering a ridiculously unlikely random gamma ray photon that spallates it into lighter elements, over these timescales that happens so many times that you can’t hope to keep track of them all even if you had some entropy-proof enormous computer. It even happens to trillions of atoms in close proximity simultaneously so many times that you can’t hope to keep track of how many times it happened. I cannot state strongly enough how mindbogglingly long these periods of time are. Immortal monkeys eventually typing at random the complete works of Shakespeare have nothing on these lengths of time; they packed up their typewriters with the job well done long before the first Boltzmann bacterium. Then unimaginably many Boltzmann bacteria would have to form and decay before the first instance of a Boltzmann bacterium that was one atom larger, and so on until you get enough atoms to form an actual brain.
Predicting the future is hard. Being confident in predicting the future is foolhardy. Confidence in the existence of Boltzmann brains requires an immensely precise prediction about how reality must proceed over unimaginable timescales in the future, far beyond any conditions that we have observed or even could possibly hope to observe, and is empty intellectual arrogance of the greatest order.
Thanks for the long answer, the only thing I did not understand is the fact of the irrelevance of the iron matter, I thought that maybe if the matter decays with iron tunneling, a boltzmann brain or other things can no longer form
Over long enough timescales any interaction will reverse, and happen again, and so on. It’s just a question of what fraction of time is occupied in each state. Or so the theory goes, at least.
therefore the matter which will perhaps decay into iron is not proof against the Boltzmann Brains hypothesis
Yes, there is no proof that they cannot possibly happen. It is a thing that theoretically could happen in a sufficiently boring universe, and there is no way to know whether our universe is sufficiently boring (but my prior odds are very much against it).
what could happen to not make it boring?
could you explain to me why?