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A review by mattbgold
Until the End of Time: Mind, Matter, and Our Search for Meaning in an Evolving Universe by Brian Greene
3.0
Doesn't really offer any unique perspectives, but overall full of elegant explanations. I particularly enjoyed the ones about gravity's role in entropy, how metabolism works, and some of the speculations on the evolutionary value of dreaming and endowing our surroundings with agency. I do wish that this book was more self-aware of it's philosophical assumptions / ideology, something I absolutely loved about "The Big Picture" by Sean Carroll. I also wasn't into the sensationalist account of the Boltzmann brain scenario - something all too common in pop science books.
*Begin potentially uninformed rant* -- The idea that we actually need to explain why we shouldn't all be Boltzmann brains strikes me as a fun but ultimately silly idea taken seriously, considering the sheer magnitude of unknown ways to produce an exactly particular configuration of particles. First of all it seems to me that you'd be far better off waiting for a nebula to fluctuate into existence that given time would coalesce into a solar system capable of evolving a brain, than to wait for a brain to fluctuate into existence on its own. Far more particles, yes - but considering that the configuration, exact position, and orientation of particles would not matter and generally the vastly higher amount of wiggle room - far higher entropy. And what's a few billion years of natural selection on the timescales of Boltzmann brains? How should "moments of conscious experience" be quantified anyway if we're going to start treating it statistically. It's not at all clear to me that a Boltzmann brain that is conscious for a nanosecond should be given the same weight as a brain sustained in an environment conscious for a lifetime. But that aside - surely there would be other even higher entropy fluctuations that would produce perfectly optimized nanoscale molecular brain-building machines. Using natural selection as an example, it's easier to build up to complexity from a simple starting point than to get a fully assembled Boeing airplane from a whirlwind in a junkyard. And from a probabilistic standpoint - any fluctuation capable of building multiple brains has that much more improbability to work with. The natural answer to all of this is that Boltzmann brains are just a fun thought experiment at the intersection of entropy and vast timescales - but one that pretty quickly breaks down under the weight of its unknowns.
**End rant**
*Begin potentially uninformed rant* -- The idea that we actually need to explain why we shouldn't all be Boltzmann brains strikes me as a fun but ultimately silly idea taken seriously, considering the sheer magnitude of unknown ways to produce an exactly particular configuration of particles. First of all it seems to me that you'd be far better off waiting for a nebula to fluctuate into existence that given time would coalesce into a solar system capable of evolving a brain, than to wait for a brain to fluctuate into existence on its own. Far more particles, yes - but considering that the configuration, exact position, and orientation of particles would not matter and generally the vastly higher amount of wiggle room - far higher entropy. And what's a few billion years of natural selection on the timescales of Boltzmann brains? How should "moments of conscious experience" be quantified anyway if we're going to start treating it statistically. It's not at all clear to me that a Boltzmann brain that is conscious for a nanosecond should be given the same weight as a brain sustained in an environment conscious for a lifetime. But that aside - surely there would be other even higher entropy fluctuations that would produce perfectly optimized nanoscale molecular brain-building machines. Using natural selection as an example, it's easier to build up to complexity from a simple starting point than to get a fully assembled Boeing airplane from a whirlwind in a junkyard. And from a probabilistic standpoint - any fluctuation capable of building multiple brains has that much more improbability to work with. The natural answer to all of this is that Boltzmann brains are just a fun thought experiment at the intersection of entropy and vast timescales - but one that pretty quickly breaks down under the weight of its unknowns.
**End rant**