Saturday, January 07, 2006

The Sim Within

I've posted before about the Universe As Simulation concept. Of those in the software industry that actually ponder such things, most subscribe to some variant of this notion. (To those with hammers, everything looks like a nail...)

In order to run a simulation the size of the universe, we would require processing power to represent approximately 1080 particles in a simulation (estimated number of particles in the universe) - let's say about 1090 bits. Should quantum computing make some headway, it wouldn't take an inconceivable number of qubits - maybe 300 to 400 - to represent this many bits in a superposed state.

Wow - only a few hundred qubits! Maybe we could actually find it in our power to simulate a universe ourselves. (Would the inhabitants of this simulated universe view us as gods?)

But wait - there's a flaw in this logic. If in fact we are able to construct qubit registers of that size that can run all these superpositions without decohering, then it would imply that the processing power is coming from somewhere outside this universe. (The easiest way to think about what is "outside" our universe is to use Everett's Many Worlds interpretation of quantum mechanics, where there is an infinite number of universes, one for every time a quantum event's probability wave "collapses").

So to really run a simulation of the universe as we really think it exists, we would need to have a very large number of separate universe simulations running at the same time, and somehow entangle the simulations all together such that quantum events could take place in all universes according to their probability distribution.

And by "a very large number", I mean a number that can break up a probability distribution fine enough to handle all the possible outcomes - so at least another 1090 simulations (each simulating 1090 particles).

Dang - so close to being supreme beings.

I was wondering, though. When we design and run a simulation, we do so for a couple of reasons. One is to attempt to model some "real world" process, so that we can better predict events yet to come. The other reason we run simulations is to find out the outcome of something that can't be known in advance.

So if the universe (or multiverse) is just a very large simulation, then who designed it? And what are they trying to find out?

Maybe we're just running in a simulation designed by ourselves many years in the future, where we're trying to simulate "the real world" to the point where we can make predictions about our future. (Good thing we have concepts like closed timelike curves to keep me out of infinite regressions - using this concept, it is possible that our future selves can build a simulation that would in fact have created their own origin).

Perhaps each universe in the multiverse is just another simulation run by beings who finally developed enough computing power to run a simulation of (at least) one universe.

Almost makes me believe in Intelligent Design.

Almost.

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