Limits of simulation

[Guest sheep_robby]

Hi,

I was discussing the anthropic principle with a physicist friend, specifically Nick Bostroms argument 'Are you living in a computer simulation?', http://www.simulation-argument.com/

 

His response was, words to the effect, that the problem for physicists is one of storage i.e. to store data on fundamental particles you will need to use at least one of said particles.

 

To be completely honest, its beyond me somewhat. I have read around this subject a bit (Bostrom, Tipler etc) and this argument of storage has thrown me completely. So, could we simulate a (our) universe or is it not physically possible?

 

Hope that makes sense.

cheers

Rob

[Dapthar]

His response was, words to the effect, that the problem for physicists is one of storage i.e. to store data on fundamental particles you will need to use at least one of said particles.

Sure, seems about right. However, you don't need to simulate every particle all the time. It's similar to the way rendering engines in video games work, namely, they only draw what the player would see.

 

As mentioned in the paper you referenced:

 

Simulating the entire universe down to the quantum level is obviously infeasible, unless radically new physics is discovered. But in order to get a realistic simulation of human experience, much less 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. The microscopic structure of the inside of the Earth can be safely omitted. Distant astronomical objects can have highly compressed representations: verisimilitude need extend to the narrow band of properties that we can observe from our planet or solar system spacecraft. On the surface of Earth, macroscopic objects in inhabited areas may need to be continuously simulated, but microscopic phenomena could likely be filled in ad hoc. What you see through an electron microscope needs to look unsuspicious, but you usually have no way of confirming its coherence with unobserved parts of the microscopic world. Exceptions arise when we deliberately design systems to harness unobserved microscopic phenomena that operate in accordance with known principles to get results that we are able to independently verify. The paradigmatic case of this is a computer. The simulation may therefore need to include a continuous representation of computers down to the level of individual logic elements. This presents no problem, since our current computing power is negligible by posthuman standards.

So, could we simulate a (our) universe or is it not physically possible?

A complete simulation would require another universe to run the simulation in, but one that people couldn't tell from reality is plausible, or as the author of the paper puts it:

 

Posthuman civilizations would have enough computing power to run hugely many ancestor-simulations even while using only a tiny fraction of their resources for that purpose.