Is The Boltzmann Brain Theory Plausible?

So say you’ve got a universe and there’s a kinda empty chunk of it. No planets, no big dust clouds… it’s pretty boring and could be considered “empty”. A few seconds later, there’s just a human brain floating there, in the middle of the space. Of course, like any human brain, it’s got no access to anything it needs to survive, so it stops working immediately.

The main idea is that it’s more likely for a human brain — complete with memories from an entire lifetime — to spawn in the middle of space than it is for science to develop the way it did.

That’s the boltzmann brain theory — but exactly how plausible is it?

Where This Wacky Idea Came From

The idea originated from an argument between physicists (like there aren’t a ton of those!) about the likelihood that science would evolve in the very specific way it did. The theory came (more specifically) from a reductio ad absurdum on Ludwig Boltzmann’s published paper that tried to explain reasons for low entropy in the universe.

This is a pretty solid definition of entropy. It more easily represents the disorder which will occur after a random happenstance, such as dropping bricks or letting particles float.

As it’s a physics thought experiment, no one’s ever actually measured it. However, the Boltzmann brain theory sums up to the idea that theoretically, after a given period of hundreds of thousands of years, atoms will come together and randomly form a human brain in the middle of space.

This would happen due to random fluctuations that come from thermodynamic equilibrium. Thermodynamic equilibrium can be defined as a point in which thermodynamic potential is minimized and entropy maximized. That just means that there’s less heat/possible heat transfer but an increase in randomness of the outcome.

Above, a basic theoretical carnot heat engine is pictured. In corresponds with thermodynamic heat transfer principles.

After thinking about the possibility of Boltzmann Brains, it turns out that there are actually two options which could result in the creation of a Boltzmann Brain:

1. Through nucleation. This would work if the current, observable universe isn’t a Minkowski space but is instead a de Sitter universe (the difference is the de Sitter is just a cosmological solution to the Einstein theory of relativity, the Minkowski is a combination of the three dimensional Euclidean space and four dimensional manifold). In theory, the Boltzmann brain would form via nucleation of non-virtual particles (interesting resource on those here: https://www.scientificamerican.com/article/are-virtual-particles-rea/)gradually assembled by chance. After appearing, the brain would cool off and then decay.
2. Through quantum fluctuation. This would require a Minkowski vaccuum to occur, and it would simply play upon the idea of quantum fluctuation providing small amounts of energy to isolated activity. Through this random fluctuation of quantum energy, eventually by chance it would be put into the creation of a Boltzmann brain.

Theories That Help Explain The Boltzmann Brains

So far, physicists are still arguing over the probability of the brains existing, but they have agreed on a couple other theories which could help better explain Boltzmann brains. Let’s take a look at them!

• Degrees of freedom in the quantum vacuum. Starting off with vacuum state, it starts off by stating that the vacuum is the point with the least amount of energy happening and existing. Instead of just being totally empty, the universe has a ton of little electromagnetic waves which “pop” in and out of the vacuum. With the Boltzmann brain second theory of creation, this suggests the amount of electromagnetic waves which could potentially provide energy to the little brain.
• The holographic principle. This is series of connected string theories and the proposed “quantum gravity” which states that the volume of space could potentially have a lower-dimensional region. However, thus far we don’t have a great understanding of the holographic principle, which would still be determined to help understand Boltzmann brains more.

The Modern Connotations Of Boltzmann Brains

There is the belief that after a point in time, there will exist more Boltzmann brains by sheer chance than there will human brains at one point in time. However, after intense discussion, many theorists observing the Boltzmann brain theory believe that this would fully discredit the theory. This is because quantum fluctuations are far easier to exclude than actual, nucleated brains complete with memories.

An alternate question is also whether or not the brains will be smarter than us, perhaps even hyper-intelligent to some extent, but as they’re theoretical no one really knows.

When dealing with a single-universe look at the theory, there’s only one de Sitter universe which would, in turn, give a cosmological constant of space. A measure of a finite amount of space should logically result in a certain number of Boltzmann brains — and if this universe, however finite in size, exists forever, then there will be an infinite amount of Boltzmann brains.

When understanding the infinite supply of Boltzmann brains, it’s important to understand than under any other circumstances (i.e. an anit-de Sitter universe or a finite universe or even the theory called “death by Higgs” — leading to universe collapse) infinite supply of the brains would be avoided.

Additionally, when observing the infinite multiverse take on the subject, depending on the observer and the position in which they were observing the brains, different measures would come out. However, given that the multiverse is infinite, then the observer should logically find an infinite number over an untapped period of time.

What It All Comes Down To

There’s not a ton this wacky theory has to do with everyday life, but it’s connotations are both fascinating and terrifying. However, the understanding about this theory basically comes down to the following:

1. The Boltzmann brain theory gives the idea that it’s more likely for a brain to spawn, complete with memories, in the middle of space than it is for science to have developed (and continue developing) the way it did.
2. Creating of Boltzmann brains could theoretically go one of two ways: either it would work with nucleation or quantum fluctuation. Either way, the brain would have the ability to spawn pretty randomly and have almost zero affluence on the rest of the universe. Almost immediately after spawning, it would die due to lack of proper chemicals needed to sustain itself.
3. Despite this, there are two huge theories which understanding would greatly help understanding the brains. These are the degrees of freedom in the quantum vacuum and the holographic principle. However, there still is a lot of understanding of physics which we have to do before we’re fully equipped to comprehend everything about the brains.
4. Looking at the modern Boltzmann brains, there are still two major points to look at before understanding whether the supply of brains will be untapped or not. This can be broken down to whether or not the universe exists infinitely (either in space or time).

At any rate, although this theory doesn’t really affect us, it still has major psychological and philosophical connotations which can affect our ways of thought and understanding about the universe.

Thank you for reading my article! I hope you enjoyed it! If you want to talk more about this craziness, please email me at amesett@gmail.com or find me on LinkedIn!!