Monday, March 12, 2007

The Universe as a Computer Simulation, Quantum Mechanics

I had a thought last week. Say you wanted to build a simulated universe, and your simulation would contain intelligent beings. To conserve computational resources, you would want to avoid simulating aspects of the universe that are not observed by its inhabitants. It would be like a colossal view frustum culling process. For example, events that are very small or very far away from an observer might not need to be computed.

If our universe is a computer simulation, maybe that's why we see quantum mechanical effects. The detailed positions of individual particles remain in indeterminant states until they are observed, at which point their wave functions collapse (i.e. their states are computed in more detail).

Interestingly, this entire thought process assumes that the observer has a very important role in the simulation, as if the universe were designed for intelligent beings.


BilloBallo said...

It's an intriguing idea. In the future, when fast enough computers exist, mankind might realize that the world is not distinguishable from a computer program. Nowadays, it's too much a stretch of imagination to think of computers that could possess enough power to "render" the world as we know it. But, if the computer only renders what is observed, the amount of computation needed is dramatically less. The hard question is, what or who qualifies as an observer, and first of all, who observes the observer...

Tyler Streeter said...

"Nowadays, it's too much a stretch of imagination to think of computers that could possess enough power to "render" the world as we know it."

That's definitely true. Even with exponential growth in computing power, any kind of Matrix-like simulation is very far off. But it doesn't matter what kind of computers we can imagine/build within our universe; the universe simulation computer is outside the simulation and will always be more powerful than anything we build within the simulation.

And we can't really complain that the universe simulation runs too slowly or looks fake because it's all we have ever known. Same thing with a 1980s video game: Pac Man lives in a certain universe, simple compared to ours, but cannot imagine anything more complex than is possible to simulate on that 1980s computer. I wonder if it's even possible for any observer to deduce the degree of complexity of their particular universe relative to others. Maybe ours is like a 1980s arcade game compared to some. (When it's over, someone pops in a quarter and starts a new big bang...)

There's probably a fundamental law that the upper bound on any machine is the computational power of its universe simulation computer. (Kind of like when you use one machine to emulate another machine, the emulation can never be more powerful than the original machine.) But I suppose if you wanted you could try to approach that upper bound by converting all resources in the universe into a gigantic computer. I don't know why you would want to do that, though...

"The hard question is, what or who qualifies as an observer, and first of all, who observes the observer..."

I'd say the definition of an observer is in general arbitrary; you can decide what's an observer based on the point you're trying to make. For the argument here (saving computational resources by only simulating things that significantly affect the observer), the observer is any intelligent entity. Or, since "intelligence" isn't really binary, the most interesting/important observers are the most intelligent entities. So more computing power goes towards providing a consistent experience to the most intelligent entities. Why would this be important? Maybe the "outside observer" (the one in control of the universe simulation) wants to experiment with the more intelligent entities within the simulation. Maybe the most intelligent simulated observers are in some way similar to the outside observer, so their activities provide the most valuable knowledge.

Who observes the observer? My only guess is along the lines of the film The 13th Floor: there is an endless hierarchy of simulations. Each one is created by some entity within another simulation (to learn something, to have fun, to satisfy curiosity, etc... same reasons we create video games today).

Anonymous said...

I too have considered an unrealistically powerful computer simulation of the universe that run from the beginning of time and it simply included fundamental rules of nature and the matter at an instant to run the entire simulation.

This would be a pretty good test for how accurate our rules of nature truly are. There are probly too many complications with computations that large having bugs and such that would cause error.

But anyways, there are also the ethical considerations of creating our universe and all matter, life, and consciousness as we know it onto a system that gets outdated really really fast and gets really crappy over time and use.