Quantum twist could kill off the multiverse, and Boltzmann brains

THE multiverse is dead, long live the multiverse. A radical new way of looking at quantum mechanics suggests that even the multiverse will come to an end.

A popular view of the multiverse says that our universe is just one of an ever-inflating multitude of discrete “bubble” universes. These bubbles are eternally budding off new universes even as individual universes age and die.

But a new view of quantum effects – the brainchild of Sean Carroll at the California Institute of Technology and his colleagues – challenges this picture. It is also potentially very useful to quantum theorists, as it does away with some thorny issues that currently dog cosmology, including a particularly baffling paradox involving disembodied consciousnesses known as “Boltzmann brains”.

via Quantum twist could kill off the multiverse – physics-math – 14 May 2014 – New Scientist.

Boltzmann brains are an interesting, and somewhat disturbing concept.  Basically, as I understand it, the idea is that in a universe of infinite space and time, matter would at times randomly coalesce into a temporary functional brain.  This brain might have memories (false ones) of an entire life and have what it thinks are ongoing sensory inputs.  The brain might only hold together for a few seconds, but during that time, it might believe it lifetime of experience behind it, that it lived in a world, and that it had a future.

The kicker is that in this infinite universe, Boltzmann brains are believed to outnumber brains in evolved creatures.  (I think the reason is that the portion of time that will allow the evolution of intelligent life is a literally infinitesimal portion of the time line of an infinite universe.)  In other words, there is a higher probability right now that you are a Boltzmann brain, that your memories are all false, and that you will momentarily dissolve after a brief flash of consciousness.

Still here?  Okay, you might be good then.  Unless of course your memory of reading the above is itself false and you still will dissolve in a few seconds.  Obviously this line of reasoning borders on solipsism.  Still, if we do live in an infinite universe, this is a logical possibility.

Apparently, Sean Carroll has found a way to banish infinity and as a result, Boltzmann brains.  I’m sympathetic, but I don’t think that’s sufficient reason to justify a scientific theory.  Of course, I doubt it’s Carroll’s only reason, and it does have some interesting consequences for multiverse theories.  Like all multiverse theories, this is playing with mathematics and logical concepts but remains well outside of observational testing, at least for now.  (Must…resist…urge…to mention philosophy 🙂 )

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13 Responses to Quantum twist could kill off the multiverse, and Boltzmann brains

  1. Ignostic Atheist says:

    Interesting, but the business of ending like it begins brings to mind conformal cyclic cosmology.

    But try this on for size: existence beyond a Bolzmann brain relies upon continuity of experience. If the multiverse really is infinite, there is a Bolzmann brain out there that is thinking your next though. If you cease to exist, it will think that thought, and pass it on to the next. Does location really matter? Hell, does time even matter? Every moment of your life would be accounted for at some point in the multiverse.

    I still think evolution is much more versatile for creating brains.

    Liked by 1 person

    • That’s a fascinating insight. It’s like the fact that in an infinite universe there are an infinite number of copies of us, a portion of which live on despite how improbable it might be. “We” continue, provided we’re content to regard “us” as the configuration of atoms, the patterns that make us up. It’s a pity that our instinctual need to survive is intensely focused on our current instantiation.


    • John says:

      No it will not think the next thought.
      The BBrain is just a random fluctuation with no rhyme or reason to the next thought in a sequence. In fact it is not even technically a thought..its just mimicking the precise configuration of the totality of all that has come to bear at that precise moment. What happens next is not based on, in any way, what came before it. In short..BBrain are not thinking.
      The BBrain should be instruction only in that in shows us unequivocally that we are real and there are no multiple “instantiation” of us. All of this type of pointless reasoning is nothing more than an attempt to further distance yourself from that truth to preserve your worldview. The very fact that you have an opinion on it–that YOU reasoned out and produced the thoughts you typed prove the futility of arguing for your position. Its simply self refuting to think you have any point at all if there are more of you or that you do not possess freewill. Unless you’re willing to imagine your Boltzmann Brains next thought will be in total disagreement with you, rendering your conclusions as random as a poop stain on the universe.
      The Mutiverse is nothing more than a corner to hide in. Any reasonable and unbiased thinker will realize its incoherence if they remain in that comer for more than a few minutes. When you come to see that every single person whose opinions you trust, including your own, have myriads of doppelgangers that have at a this precise moment, in a separate universe exactly like ours, changed their minds and have now come to the conclusion that multiverse is the comic book explanation we all knew it was…you will jettison the idea as a reality destroyer–taking logic, reason, argumentation, scientific results, and probability and flushing it down the toilet. You have to see that’s too high a price to pay–and if you dont…that’s OK…..none of your doppelgangers agree with you.


  2. Howie says:

    Must…resist…urge…to mention philosophy

    Be careful – Neil deGrasse Tyson will not approve! 😉

    This is fascinating stuff. I first learned of Boltzmann brains watching Sean Carroll debate William Lane Craig. I am also at a loss at explaining the whole justification of a theory based on eliminating Boltzmann brains. I don’t think it matters too much though, because I’ll likely disappear in seconds…. later. 😉

    Liked by 1 person

    • That’s where I first heard of them too, although the debate didn’t give a good description, and I found the Wikipedia article at the time unhelpful. Tegmark gave a good description in his book, ‘Our Mathematical Universe’.

      …at least that’s what I remember, assuming I’m not about to disappear.


    • john zande says:

      Me too, Howie…. the bit about first hearing about brains during that debate. I disappeared three seconds ago. 🙂


  3. “(Must…resist…urge…to mention philosophy 🙂 )”

    That means this wasn’t philosophy the whole time? I’ll be the first to admit I don’t know much about multi-verse theories (my formal training is mostly ancient, medieval, and political philosophy), but I’m sort of baffled that this “counts” as science after all the comment section arguments I’ve been reading in the wake of dGT-gate 2014.

    Liked by 1 person

  4. “Boltzmann in Wonderland”, by one Carroll again…


  5. Steve Morris says:

    Beware of infinities … that’s my advice.


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