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.

Vaping changes blood vessels after one use, even without nicotine

E-cigarettes may be safer than traditional cigarettes, but they come with their own risks.


John Keeble
/GETTY
Surprising Science
  • A new study used an MRI machine to examine how vaping e-cigarettes affects users' cardiovascular systems immediately after inhalation.
  • The results showed that vaping causes impaired circulation, stiffer arteries and less oxygen in their blood.
  • The new study adds to a growing body of research showing that e-cigarettes – while likely safer than traditional cigarettes – are far from harmless.
Keep reading Show less

First solar roadway in France turned out to be a 'total disaster'

French newspapers report that the trial hasn't lived up to expectations.

Image source: Charly Triballeau / AFP / Getty Images
Technology & Innovation
  • The French government initially invested in a rural solar roadway in 2016.
  • French newspapers report that the trial hasn't lived up to expectations.
  • Solar panel "paved" roadways are proving to be inefficient and too expensive.
Keep reading Show less

America’s education system is centuries old. Can we build something better?

The Lumina Foundation lays out steps for increasing access to quality post-secondary education credentials.

Sponsored by Lumina Foundation
  • America's post-high school education landscape was not created with the modern student in mind. Today, clear and flexible pathways are necessary to help individuals access education that can help them lead a better life.
  • Elizabeth Garlow explains the Lumina Foundation's strategy to create a post-secondary education system that works for all students. This includes credential recognition, affordability, a more competency-based system, and quality assurance.
  • Systemic historic factors have contributed to inequality in the education system. Lumina aims to close those gaps in educational attainment.
  • In 2019, Lumina Foundation and Big Think teamed up to create the Lumina Prize, a search to find the most innovative and scalable ideas in post-secondary education. You can see the winners of the Lumina Prize here – congratulations to PeerForward and Greater Commons!