# Infinity: Why the universe could easily be a computer simulation

As promised, here is the second part of the Pi argument. As I mentioned in the previous article, Pi is irrational, and therefore cannot be completely calculated or represented by a computer. People make sport out of calculating more and more of Pi’s decimal places using various kinds of supercomputers and distributed computing projects, precisely *because* it is impossible to calculate it in its entirety on a computer that has finite memory. So, our universe, that contains so many round forms that involve Pi as the ratio between their radius and their circumference must therefore surely not be inside a computer?

To quote “Radio Erewan”, “**in principle, yes, but…**”

The thing is, the context in which we looked at Pi — as part of the circumference and surface of particles — doesn’t actually need to be simulated — not even in a particle-based simulation. All you ever need to, say, find out whether a collision between two particles took part, is their location and their radius — this is the way they do it in computer games, anyway.

Even if you did have to emulate objects in full — every object is composed of atoms, discrete chunks, just like pixels on the screen. There is no “circumference”, just atoms bouncing around.

To add insult to injury, the observable universe — the region of space we can see — is finite, due to the speed of light — and will always be due to faster-than-light expansion of the universe. Since no signals can travel faster than light, particles outside a certain boundary region will **never** have the chance to interact with us in any way — so there is only a limited amount of matter to simulate, if you wished to do so.

Even reality itself appears to be quantized — to come in discrete chunks of space and time, the Planck length and Planck time. Every unit of every energy comes pre-packaged into discrete chunks, quanta. (Light: photons. Sound: phonons… and so on). This is where the word **quantum **physics comes from. Every particle can assume only a final amount of states. It is as if the whole universe is comprised of multidimensional “voxels” (**vo**lumetric pi**xels, **a technology used in some early 3d computer games to represent “rounded” shapes, like hills etc.) So even the total number of states in the entire universe is finite, simplifying the simulation even more.

Even worse, **reality even cheats **on the precision of the entire thing, due to the Heisenberg’s Uncertainty Principle.

In fact, the entire quantum mechanics is based on the notion that particles behave like waves, and as you can see by shooting a *single* photon or an electron through a *pair* of very thin slits, they are “*probability* waves”, since in the end, the single photon or electron doesn’t magically separate into “something” and smear itself in a diffraction pattern, but instead hits one single spot — and what spot it hits is determined by a diffraction pattern. Ie what you can say when conducting such an experiment is not “this is where the electron will hit” but instead, “the probability of the electron to hit in this strip here is higher then in this strip next to it”. More about this completely non-intuitive finding in “The Quantum Experiment that Broke Reality” (by PBS Spacetime).

What does that mean for a computer simulation of our reality? To a certain degree, to calculate whether a bunch of particles are supposed to interact, it is enough to “throw virtual dice” within certain parameters — a vast efficiency improvement on having to calculate the trajectory of each and every particle and intersect them with all the others (and the reason why radiosity can be faster then ray tracing).

So if the reality *is* a computer simulation, the programmer(s) have even cheated a little, to save computational resources. No wonder, considering just how many particles there are.

There is a number of other things about our reality that are peculiar, and look like they are designed to optimize the simulation. For example, while life is bound to consume more and more computing power because it involves very complex interactions that can not be simulated by bulk calculations (like a star, or a dumb chunk of rock), and since the advent of technology humans are relying on more and more precisely interacting machinery, that would need to be simulated in detail — the accelerating expansion of the universe takes larger and larger chunks of the universe outside the zone in which it can interact with us — as if to reduce the computational load.

Maybe, the reason why no one has produced a convincing “theory of everything” so far, is precisely that — it is simply a computer simulation, and, to paraphrase Neil deGrasse Tyson, the programmers were under no obligation to make sense to us.

Of course, this leaves us with many questions. If it is a computer simulation, what lies outside of it? And if it is not, where did it come from? I will try to address these, and other questions in the rest of the Infinity series, articles like Infinity: We have been here before.