Season 17, Episode 12: Are We Living in a Simulation?

Hey StarTalkers! Season 17, episode 12 sees Neil and Paul go through some cosmic queries with legendary mathematician Terence Tao. A reader question near the end of the episode opens up a potentially huge discussion: Do we live in a simulation?

Is the Universe a Math Problem? With Terence Tao - StarTalk Radio

(starts at 49:30)

They discuss the idea for a few minutes – and it’s been covered on StarTalk before – but as always with these “cosmic queries” discussions, there isn’t much time to go into detail.

So, what exactly is simulation theory and why do so many people seem to believe it? Let’s dig in.

Bostrom’s Paper

The modern form of the simulation hypothesis comes from a 2003 paper by Nick Bostrom .

First, he argues that it should be possible to simulate consciousness. Bostrom is talking sci-fi more than “real life,” rooted in known science but pushed to the extreme. If we had a computer the size of a planet, he concludes that we could simulate “the entire mental history of mankind.”

In other words, we could simulate every human brain to ever exist.

The Three Possibilities

This leads to three possibilities:

1. No human-level civilizations reach this technological level. Either large-scale disaster (man-made or not) or technological stagnation could prevent this from happening.

2. No human-level civilization at this tech level is interested in making such simulations. After developing to this level, human-level civilizations could simply lose interest in making these simulations. Maybe they’re too advanced to benefit, or think it’s cruel to simulate human-like minds.

3. We are almost certainly living in a simulation. If 1) and 2) aren’t true, then it’s likely there are many simulations. If there are simulations within simulations, the number becomes truly huge (see image below). At this point, a simple count of “real” vs. simulated realities makes it almost certain we’re in a simulation.

Improving the Estimate

Bostrom basically compares numbers (real vs. simulated) to make his famous argument. But there’s a slightly improved, Bayesian calculation that just puts us at just over 50% odds of living in a true reality. One key difference is assuming some limit to simulations within simulations – eventually, computing power runs out.

So toss a coin. If you call it right, maybe we’re real.