My mind keeps wandering back to Bostrom’s session. You might think that discussing the probability of human extinction due to war, disease or accident is a likely cause of insomnia. The simulation hypothesis in particular is the stuff that dreams and nightmares are made of - a modern religion with an omnipotent programmer. In this light, it is not so surprising that the simulation hypothesis is popular on the internet, though Keanu Reeves clearly had a role in this popularity, which now gives me an excuse to decorate my blog with his photo.
But while I do sometimes get headaches over questions concerning the nature of reality, the simulation hypothesis is not among the things that keep me up at night (neither is Keanu Reeves, thanks for asking). After some soul searching I realized that I don’t believe in the simulation hypothesis for the same reason I don’t believe in alien abductions. Before science fiction literature and its alien characters became popular, there was no such thing as alien abduction. Instead, people commonly thought they were possessed by demons. It is believed today that sleep paralysis is a likely origin of hallucinations and out-of-body experiences, an interesting topic on its own right, but the point here is that popular culture creates hypotheses, and present culture is a collective limit to our imagination.
People today ponder the idea that reality is a computer simulation in the same way that post-Newtonian intellectuals thought of the universe as a clockwork. The clockwork universe theory seems bizarre today, now that we know many things that Newtonian mechanics cannot describe. But then people used to wear strange wigs and women stood around in dresses barely able to walk, let alone breathe, so what did they know. And chances are, 200 years from now the simulation hypothesis will seem equally bizarre as the idea to transfer fat from the butt to the lips or take notes by rubbing graphite on paper.
A more scientific way to phrase this is that the simulation hypothesis creates a coincidence problem, much like the coincidence problem for the cosmological constant. For the cosmological constant the coincidence problem is this: Throughout the expansion of the universe, matter dilutes and the constant stays constant. Why do we just happen to live in a period when both have about the same value? For the simulation hypothesis the coincidence problem is this: Why do we just happen to live in a period where we discover the very means by which the universe is run?
To me, it’s too much of a coincidence to be plausible. I will put this down as a corollary of the Principle of Finite Imagination “Just because humans do not or cannot imagine something doesn’t mean it does not or cannot exist.” Corollary: “If humans put forward a hypothesis based on something they have just learned to imagine, it is most likely a cultural artifact and not of fundamental relevance.” Though the possibility exists that present day human imagination is the eclipse of scientific insight, the wish to be special vastly amplifies believes in this possibility.
That having been said, another way to approach the question is to ask for scientific evidence of the simulation hypothesis. There has been some work on this, and occasionally it appears on the arxiv, such as this paper last year which studied the possibility that The Simulator runs state-of-the art lattice QCD. I find it peripherally interesting and applaud the authors for applying scientific thought to vagueness (for other attempts at this, check their reference list). Alas, the scenario that Bostrom has in mind is infinitely meaner than theirs. As he explains in this paper, to save on calculational power only that part of reality is simulated that is currently observed:
“In order to get a realistic simulation of human experience, much less [than simulating the entire universe] is needed – only whatever is required to ensure that the simulated humans, interacting in normal human ways with their simulated environment, don’t notice any irregularities.”So you’d never observe any effects of finite lattice spacing because whenever you look all symmetries are restored. Wicked. It also creates other scientific problems.
To begin with, unless you want to populate the simulation by hand, you need a process in which self-awareness is created out of simpler bits. And to prevent self-aware beings from noting the simulation’s limits, you then need a monitoring program that identifies when the self-aware parts attempt to make an observation and exactly which observation. Then you need to provide them with this observation, so that the observation is the same as they would have gotten had you run the full simulation. This might work fine in some cases, say, vacuum fluctuations, because nobody really cares what a vacuum fluctuation does when you’re not looking. If you have a complex system however, reducing the complexity systematically and blowing it back up is difficult if not impossible.
Take a system that’s still fairly simple, like a galaxy. If nobody is pointing a telescope at it, you don’t want to bother with its time evolution. But then how do you make sure that observations at different times are consistent? And then there’s the possibility that somewhere in the galaxy that humans weren’t observing intelligent life developed that would one day land on planet Earth. If your simulation by design doesn’t take into account events like this, it’s strangely anthropocentric. It also then raises the question why bother with 7 billion people to begin with? Would not an island do, and the rest of us pop in and out of existence to amuse the islanders? This reminds me, I have to book a flight to Iceland.
To avoid these problems, The Simulator would use a much simpler method: deter observations that might test the limits, much like it is difficult to reach the boundary of Dark City. And suddenly it makes sense, doesn’t it? All the recent budget cuts to research funding, even in areas like theoretical physics, the possibly most cost-efficient insight engine running on little more than graphite rubbing on paper. It’s all to deter us from discovering the boundaries of our simulation. Now if saying hello to the programmer who runs the simulation we live in isn’t an argument to support basic research, then I don’t know what is. I’ll leave you with this thought and book my flight before I pop out of existence again.