A Boltzmann Brain is a hypothesized self-aware entity, which arises due to random fluctuations out of some (future) state of chaos. I.e. they are hypothetical brains resulting from thermal or vacuum fluctuations - Boltzmann Brains comes from nothing... In stark contrast to a human brain, which is the result of an evolution stretching back through most of the history of planet Earth.
What are the chances then that an everyday object - a rock, a chair, you name it - could suddenly appear out of thin air? Not zero, surprisingly.
In fact, given enough space and time, it is conceivable that a conscious being could arise, even if only for a microsecond.
Surely, if there are many Boltzmann Brains out there, it gives yet another twist to the Copernican principle, that humans are not privileged observers of the universe!
All is not unanimity out in netland though. Have just read yet another ''Boltzmann Brains can't be true''-blog. It makes me wonder what people actually think (is) out there?
Surfed around for some answers (see below):
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The universe is not only stranger than we imagine, it is stranger than we can imagine.
Haldane. Possible Worlds and Other Papers (1927), p. 286.
Most animals have brains, in some way or another. Over time, animals' brains have become more complicated because of evolution. Humans might have the most complicated brain.
People used to think that only humans had a sense of humor, but apparently the octopus also has a sense of humor.
Wikipedia.
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Biology books tell us that brains came about as the result of evolution. Usually it goes something like this:The human brain is the result of an evolution stretching back through most of the history of the planet. Earth formed around 4.6 billion years ago. A billion years later life emerged in the form of simpleorganisms such as bacteria. Things started to be a little more interesting a billion years ago with the emergence of organisms consisting of more cells. Then some cells took specialized roles. One such specialized cell was the nerve cell (neurone). As evolution proceeded, nerve cells tended to work togetherin neural networks (the first brains). 570 million years ago came the Cambrian explosion, with a sudden increase in the diversity of life on Earth. Following the Cambrian explosion, large brains with elaboratesensory systems appear to have evolved twice, independently. Once among the cephalopods (octopus) and once among our fish like ancestors, the chordates.
So far so good. But then came the ''mad cosmologists''. And introduced us to other kinds of brains.The weird Boltzmann Brains (Susskind, Dyson, Kleban 2002). According to New York Times:You might wonder what’s wrong with a few brains - or even a preponderance of them - floating around in space. For one thing, as observers these brains would see a freaky chaotic universe, unlike our own, which seems to persist in its promise and disappointment. Another is that one of the central orthodoxies of cosmology is that humans don’t occupy a special place in the cosmos, that we and our experiences are typical of cosmic beings. If the odds of us being real instead of Boltzmann brains are one in a million, say, waking up every day would be like walking out on the street and finding everyone in the city standing on their heads. You would expect there to be some reason why you were the only one left right side up.
Charlie Huenemann explains the second problem in laymans terms like this:
The basic idea, as I understand it, is this. Scientists think that the universe’s level of disorder,as a rule, never decreases. What this means is that things decay, disperse, and lose any non-uniform distribution of qualities over time. You can’t unscramble an egg; you can’t unswirl the cream in your coffee; you can’t make the universe, as a whole, warm up, or even stay the same temp. This is the secondlaw of thermodynamics: disorder (entropy) never decreases. That’s a law for the universe as a whole. It doesn’t preclude little isolated burps of increasing organization, so long as, over the long haul, there is a net loss in order. So the universe can tolerate isolated exceptions to the second law. But, since nature seems to always choose the simplest path, these exceptions should be kept to a minimum.Here comes Boltzmann: Suppose the universe had two choices: One is to allow the great big exception to the second law known as the history of human evolution and civilization. The second is to allow the comparatively minor exception which would have you spontaneously come into existence, for a few seconds, with all the memories, perceptions, and expectations you are experiencing right now. Case number two is the smaller breach ofentropy. So we should believe that that’s the truth:You think you are part of a great big exception to entropy, but you’re not. You’re something like a one-second-old brain in a vat. A Boltzmann Brain.
Wikipedia thinks this is all nonsense:The rationale behind this being paradoxical is that, out of chaos, it is more likely for one instance of a complex structure to arise than for many instances of that thing to arise. Which obviously ''ignores the possibility that the probability of a universe in which a brain pops into existence, without any prior mechanism driving towards its creation, may be dwarfed by the probability of a universe in which there are active mechanisms which lead to processes of developmentwhich reasonable probability of producing a species such as ourselves. In a universe of the latter kind,the scenarios in which a brain can arise are naturally prone to produce many such brains, so the largenumber of such brains is an incidental detail''
The same cosmologists, who got us into all the trouble also have a way out (making you real again), sort of:''On Earth humans are not typical animals; insects are far more numerous. No one is surprised by this.''So there can be Boltzmann Brains and there can be humans...phew...
Another contentious issue is whether the cosmologists in their calculations should consider only the observable universe, which is all we can ever see or be influenced by, or whether they should take into account the vast and ever-growing assemblage of other bubbles forever out of our view predicted by eternalinflation. In eternal inflation, the number of new bubbles being hatched at any given moment is always growing, Dr. Linde said, explaining one such counting scheme he likes. So the evolution of people in new bubbles far outstrips the creation of Boltzmann brains in old ones.
Numerous or not. Still, the Boltzmann Brains are still lurking out there. Read this one on Usenet:...Interstellar clouds of hydrogen, which happens to instantiate a particular Turing machine (Boltzmann Brain), but only for a tiny instant before it goes into another arrangement. Thus, not only will smaller systems be more frequent, but briefer systems will be more frequent; it is very unlikely that a large and long-lasting entity like a human brain will appear by chance, but rather more likely that very brief human brain-equivalent snapshots will arise, widely separated in time and space.
Sure, if you want to do something, it's not enough to be complex enough to be a conscious observer - you also need to be physically adapted to exist in the environment in which you appear, and since the way a Boltzmann brain is physically configured is presumably random with respect to its place of ''birth'', the chances of this are exceedingly slim.
Still, noone is saying that you couldn't have really smart Boltzmann brains in places like the inferno of the Big Bang ?And presumably, these Boltzmanns Brains could manipulate the future evolution of the universe?
Even if we could do away with all of Boltzmann Brains, the universe would still be a weird place:
One blogpost suggested that without the Boltzmann Brains - order and common sense is restored in the universe. Evolution creates brains, the end. This triggered me into writing this post - Because, I think there is still plenty of weirdness out there, even without Boltzmann Brains:
According to Hans Moravec life could exist on Neutron Stars as patterns of bounded neutrons.With a breakneck speed of metabolism. Where organisms live and die within 10e-15 seconds. Entire civilisations might be formed within a fraction of a second. Advanced civilisations might create such neutron stars in order to use them as computers. Some 10e30 more powerful than the human brain.In a previous post I have suggested an addendum to this: Future civilisations could install computers in the fabric of spacetime itself. Smash the neutron star a bit further and create a black hole,which explodes into a new universe (big bang) with the new order (computer) installed in its very fabric of space and time http://www.simonlaub.net/Post/omega260402.txt
According to Max Tegmark, current cosmological models may indicate that space is infinite in size. If so, then somewhere out there, everything possible becomes real, no matter how improbable it is. Including an identical copy of the reader.What is left is only to calculate how far away your dobbeltgaenger is! How far away must you gobefore a given configuration of particles repeats (Hubble volume) ? Tegmarks estimate is 10 to 28th meters away
http://www.simonlaub.net/Post/dobbeltgaenger.txt
Not weird enough? Then there are suggestions that everything is resurrected at the end of the universe
http://www.simonlaub.net/Post/neverendingdays.htm
Certainly, Haldane was right:
The universe is not only stranger than we imagine, it is stranger than we can imagine.
-Simon
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