This article is written by a student writer from the Her Campus at KCL chapter.

The concept of the Boltzmann brain is just mind boggling. At the heart of it lies entropy defined in a physical system as the measure of the amount of energy that cannot be used to do work. According to the second law of thermodynamics, the entropy of the universe is always increasing. We see it in our daily life, and the applications are widespread. It is what prevents us from achieving perpetual motion machines. Simply stated, any system always goes from a state of orderliness to being more random. Take the classic case of hot air in a corner of the room. Eventually, the hot air spreads out into the whole room, as a result of an increase in entropy. However, the same room, assuming it is an isolated system and is left on its own for an infinite amount of time, will go through an infinite amount of conformations, which would include the air molecules in the room going back into the original conformation, thus reducing the global entropy of the system. However, since these observations take place in infinite time, the violation of the second law of thermodynamics is never observed.

Although how the universe began is still debated, it probably started at a low entropy state with a dip in global entropy, causing all the particles to gather in one place. This resulted in the big bang and the universe has been expanding ever since. It created galaxies, solar systems, the stars and the planets and gave way to our existence. However, statistically speaking, smaller dips in entropy are more frequent than large-scale collapses like the big bang, the former leading to conscious observers. As an extension, however, it may be plausible that particles collapsed due to temporary dips in entropy, arranging in a way to form the human brain, with all the previous memories of the conscious observer and an illusion of sensation, giving it an existence into our current being.

Thus, it may seem that all of us are living in a real-life simulation, which is comparable to lifelike characters in video games where they perceive themselves to be ‘real’ but are in fact a construct. Perhaps we too live in a simulation and everything surrounding us is an illusion. It may also be concluded that we are living in an ‘ancestral simulation’ where our ancestors from a parallel universe are running continuous simulations to see how history plays out and impacts human life.

As Oxford professor Nick Bostrom has suggested, the technology to simulate the billions of synapses in the brain would be possible in a few generations. However, if we account for all the synapses in the brains of all the people that have ever lived over the course of human history, it would account for 1035 seconds. That would be the time taken to simulate a single episode. However, an advanced life form (the ones responsible for simulating our reality) may be using a Jupiter computer, which can simulate roughly the same amount of time in a single second. It wouldn’t be much of a stretch to conclude that there may be many more earths, in a similar situation, being simulated at the same time, just with different courses of history and outcomes.

The idea that these beings are simulating our world is indeed very fascinating. It’s amazing to think that the socio-political landscape may have been shaped by countless simulations to check the impact on humanity over the course of subsequent years; the greater the situation was in history, the bigger the effect in magnitude. In light of recent developments, it is somewhat relieving to think of the ongoing pandemic along with the many crises throughout the year as being a simulation to see how humanity survives in these circumstances and to look at possible socio-economic and political outcomes.

However, if all of humanity is nothing but a simulation, it begs the question if consciousness, in this realm, exists. If all of our surroundings are nothing but illusions, then the conscious mind cannot exist. Neither could free will, because all of the memories are already preprogrammed, thus ceasing any leverage that we might have over the future. If this is true, then any tasks to create Artificial Intelligence (AI) and machine learning would be futile too, as consciousness would never be replicated. Massive texts on philosophy and politics would hold no bearing on life either as they would merely address existence in a simulation. Similarly, it can be argued that nothing observed in this universe would hold meaning.

For the universe to be observable at all however, the universe should give rise to beings that can observe it (anthropic principle), and since we live in an observable universe, the observers must be real. As Sean Carman puts it, the concept of Boltzmann brains is ‘cognitively unstable’; for a brain to realise it is living in a simulation, it must be able to make its own decisions, which would be impossible if it were in a simulation. As mentioned before, the origin of the Universe is still debated and the assumption that there was an overall global dip in entropy in the first place is still not proven. However, if we were living in a simulation, according to Bostrom, the chances are less than fifty percent because either we are actually living in the ‘real world’, or if we are Boltzmann’s brain, then our ancestors chose to not run the simulations. Whatever it may be, for now, without further proof, to believe we are not in a simulation, would provide utmost reassurance.

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Boltzmann Brain

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