Want to gain a point of Real World Cthulhu Mythos?

[EricW]

Cthulhu might actually exist. Scientists have predicted the existence of unimaginably strange intelligences of potentially immense power since the late 1800s - though most scientists believe this prediction is evidence of a horrible mistake somewhere in their calculations. 

Quote

 

In physics thought experiments, a Boltzmann brain is a self-aware entity that arises due to extremely rare random fluctuations out of a state of thermodynamic equilibrium. For example, in a homogeneous Newtonian soup, theoretically by sheer chance all the atoms could bounce off and stick to one another in such a way as to assemble a functioning human brain (though this would, on average, take vastly longer than the current lifetime of the Universe).

The idea is indirectly named after the Austrian physicist Ludwig Boltzmann (1844–1906), who in 1896 published a theory that the Universe is observed to be in a highly improbable non-equilibrium state because only when such states randomly occur can brains exist to be aware of the Universe. The fatal flaw with Boltzmann's "Boltzmann universe" hypothesis is that the most common thermal fluctuations are as close to equilibrium overall as possible; thus, by any reasonable criterion, human brains in a Boltzmann universe with myriad neighboring stars would be vastly outnumbered by "Boltzmann brains" existing alone in an empty universe.

Boltzmann brains gained new relevance around 2002, when some cosmologists started to become concerned that, in many existing theories about the Universe, human brains in the current Universe appear to be vastly outnumbered by Boltzmann brains in the future Universe who, by chance, have the exact same perceptions that we do; this leads to the absurd conclusion that statistically we ourselves are likely to be Boltzmann brains. Such a reductio ad absurdum argument is sometimes used to argue against certain theories of the Universe. When applied to more recent theories about the multiverse, Boltzmann brain arguments are part of the unsolved measure problem of cosmology.

 

Source Wikipedia

The odd thing about this prediction is that it has survived several major revisions of theory. The original thermodynamic Boltzmann prediction was found to have a parallel when Quantum theory was discovered. Even the newest cosmological theories have room for Boltzmann brains in their calculations.

The famous physicist Richard Feynman added to the confusion by calculating that universes containing a single Boltzmann brain should be far more numerous than universes full of structure and stars, like our universe.
 

Quote

In 1931, astronomer Arthur Eddington pointed out that, because a large fluctuation is exponentially less probable than a small fluctuation, observers in Boltzmann universes will be vastly outnumbered by observers in smaller fluctuations. Physicist Richard Feynman published a similar counterargument within his widely-read 1964 Feynman Lectures on Physics. By 2004 physicists had pushed Eddington's observation to its logical conclusion: the most numerous observers in an eternity of thermal fluctuations would be minimal "Boltzmann brains" popping up in an otherwise featureless universe.^[2][4]

^{(Same link as above)}

If Boltzmann brain theory is correct, a big if, the only thing protecting us from unimaginably strange encounters with such entities is they are all locked away at the end of time, or locked away in different universes. The probability of such a being arising in our region of spacetime is ridiculously low, as in one in one followed by a ridiculous number of zeroes. By the time Boltzmann brains become common, the universe will be a very different place to the cosmos we know - dark and cold and pretty much empty, except for the Boltzmann brains.

Of course all this assumes we understand the nature of space and time. There may be ways to travel across the empty ages, to leave otherwise empty regions of the cosmos, to visit the brief spark of light at the beginning of our universe, the space and time we inhabit. Beings who have nothing else to do but contemplate a dark eternity will have plenty of opportunity to discover such pathways to other realms, if such pathways exist. 

This is highly speculative. The theory is so immature that the Boltzmann paradox might really just be a mistake in the calculations.

Or just maybe our island of comfort and peace is even now being hungrily eyed by the desperately ferocious denizens of a cold and empty high entropy regions of the universe, who yearn and hunger for a brief taste of our universe's brilliant light and life.

[Darius West]

There is a further problem I can see with this.  A Boltzmann brain needs not only the random fluctuations of thermodynamics to generate it, but also the means to survive and perpetuate itself.  A Boltzmann brain born in the form of a human brain that comes into existence in the vacuum of space will die rapidly.  On the other hand, a spontaneously generated solid state positronic brain with a nuclear battery may fare better.  Also, being birthed into a universe isn't the same as understanding it.  Without the means to interact via sensors and manipulative articles, plus the materials to adapt and craft, Boltzmann is going to have one profoundly bored and ignorant brain.  On the other hand, in infinite universes with infinitely varied physical constants, anything is possible.

[EricW]

Ha. I see your unviable Boltzmann brains and raise you eternity.

You are right that most Boltzmann brains will die pretty much the instant they appear. But even if the chance of a minimally viable Boltzmann brain is as unlikely as the chance of a Boltzmann brain arising in the first place (so we have tiny fractional probability multiplied by itself, producing an even more ridiculously small number), in an infinite period of time all possible unlikelyhoods are inevitable.

And there seems to be concern that if Boltzmann brains outnumber normal observers they might have strange and outlandish effects of the structure of the universe, though I don’t understand the reasoning behind this issue.

Of course all this is highly speculative.

We know other universes exist because they have been observed. The most distant stars are effectively not part of our universe, because they are forever beyond our reach - even if we had a near lightspeed starship, we could never travel to those stars because the accelerating expansion of the universe means some stars we observe billions of years away are now receding from us faster than the speed of light - they are beyond our cosmic event horizon.

Another question is what would a cosmos size Boltzmann brain look like? I suspect it would be full of planets and stars, and maybe even intelligent beings who ask deep questions about the nature of the universe.

https://en.wikipedia.org/wiki/Cosmological_horizon