Are you a Boltzmann Brain? Why nothing in the Universe may be real
A mind-bending paradox questions the nature of reality.
- Boltzmann Brains are hypothetical disembodied entities with self-awareness.
- It may be more likely for a Boltzmann Brain to come into existence than the whole Universe.
- The idea highlights a paradox in thermodynamics.
The paradox of the Boltzmann Brain can really pull the rug from under you if you follow it to all of its logical and illogical extents. This mind-churning idea proposes that the world is quite possibly just an effect of your disembodied consciousness and doesn't really exist. And your sense of self is just a statistical fluctuation. It's something that is more likely to come into existence by chance than the Universe that would have had to produce it.
So are you really a Boltzmann Brain? Let's look at the underlying thinking.
Our Universe is extremely vast and complex, still filled with as much of the unimaginable as what we have already figured out. It has laws like an arrow of time that seems to be flowing only in one direction. It's got planetary bodies of various shapes and sizes. It also has us, humans, nature's supreme creations (at least according to us). But all this amazing amount of varied matter is also very hard to pull off, requiring a tremendous amount of energy. We know that generally things tend to fall apart and decay.
What the influential Austrian physicist Ludwig Boltzmann (1844-1906), one of the founders of the field of thermodynamics, hypothesized is that while the entropy of a system (its measure of disorder) always increases (moving towards disorder), there is some tiny possibility that a fluctuation can bring a system from disorder to order. Thus it would decrease its entropy, moving it further away from equilibrium.
Ludwig Boltzmann. 1901
From the physicist's work it follows that it would be more likely for random quantum fluctuations in nature to create something simpler than our astounding Universe – for example, a self-aware entity that believes it is a person in a world full of people, history, and particular physics. But such a person - let's say you - is only full of all the knowledge and experiences because you are made that way by the fluctuation that created you. There is nothing really there but your self-awareness.
These types of entities have been dubbed "Boltzmann Brains" by modern physicists Andreas Albrecht and Lorenzo Sorbo. They did not claim to such brains really being in existence but rather used the idea to point out the absurdities and limitations of taking the idea of thermodynamic fluctuations to their extent.
Boltzmann Brains have also been criticized as philosophical paradoxes that are experientially unprovable. The Caltech theoretical physicist Sean Caroll called them "cognitively unstable: they cannot simultaneously be true and justifiably believed" in his 2017 paper "Why Boltzmann Brains Are Bad."
Debates of the idea persist, however, especially as it is hard to disprove. After all, if you were a Boltzmann Brain, everything that you could come up with to prove or disprove it would likely be because of the hallucinations your consciousness is having.
Other types of solipsistic thinking have also entered our culture. Case in point - the notion that we may be living in a simulated reality, propagated by luminaries like Elon Musk and Neil deGrasse Tyson.
Until about a decade ago, only two habitable zone planets of any size were known to astronomers: Earth and Mars.