Boltzmann brain

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A Boltzmann brain is a hypothesized self-aware entity which arises due to random fluctuations out of some future state of chaos. The idea is named for Ludwig Boltzmann, whose ideas led to the possibility of such entities. One might think of the assumption of the second law of thermodynamics as that the entropy in the universe will always increase. So we may think of the most likely state of the universe as one of high entropy, that is chaotic and without order. Within this, we should still expect to see stochastic fluctuations in the level of entropy. The most common will involve only small amounts of organization, with greater levels of organization being more rare. So our current level of organization having many self-aware entities is less likely than a level of organization which is only just able to create a single self-aware entity. Fluctuations which result in these single self-aware entities are much more common than our own over the entire time line of the universe. The Boltzmann brains paradox is that it is more likely that a brain randomly form out of the chaos with false memories of its life than that the universe around us would have billions of self-aware brains.

[edit] References

"Disturbing Implications of a Cosmological Constant", Lisa Dyson, Matthew Kleban, and Leonard Susskind, Journal of High Energy Physics 0210 (2002) 011 (at arXiv)

"Can the universe afford inflation?", Andreas Albrecht and Lorenzo Sorbo, Physical Review D 70 (2004) 063528 (at arXiv)

"Is Our Universe Likely to Decay within 20 Billion Years?", Don N. Page, (at arXiv)

"Sinks in the Landscape, Boltzmann Brains, and the Cosmological Constant Problem", Andrei Linde, Journal of Cosmology and Astroparticle Physics, 0701 (2007) 022 (at arXiv)