Re: How To Live In A Simulation

From: Robert J. Bradbury (
Date: Fri Mar 16 2001 - 10:04:31 MST

On Fri, 16 Mar 2001 wrote:

> Several people have suggested that our world is indistinguishable from a
> simulation. I disagree. One universal characteristics of simulations is
> that they simplify. If you look at any aspect in enough detail (usually not
> closely at all) it's simple.

I'm afraid I have to differ with Curt and agree with Eliezer here.

For example, I had the opportunity to overhear a conversation between
Deepak Shrivistava (a scientist who actually does molecular simulations
(of buckytubes) and knows those who do the "really" big simulations)
and Robert Freitas at the Foresight nanotech conference last fall.
Deepak indicated that there was a big difference in simulation capacity
depending on whether or not you need to put the hydrogen atoms into
the simulation. This make sense because hydrogen atoms are the
smallest and have the highest velocities. So while the simulation
might be able to operate at several nanosecond time steps without
the H atoms, do one with the H atoms in it and you have to crank it
down to sub-ns time steps. (Obviously in biological material simulations
the H atoms are important while in semiconductor material simulations
they are much less important.)

Now the interesting thing is that the "resolution" of the simulation
remains the same whether you are running it on a PC or a supercomputer.
(The code is the same after all). What changes is the ratio of real
time to simulation time. If we are in the simulation the SI could be
dynamically adding and removing processors devoted to running it,
speeding it up and slowing it down and this would be totally undetectable
from our perspective.

Simulations do not "have" to simplify things to the point where they can
be detected (it may be cost effective to do that). But if they want to
devote enough resources to creating the complexity required "on demand"
they should make it extraordinarily difficult, perhaps impossible, for
us to tell the difference. It isn't clear to me, if as we move to the
theoretical limits of physical laws, whether the creation could develop
incongruities that would cause us to become very suspicious. Maybe
that should be a topic for Extro 6.


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