From more recent reading on quantum physics, I no longer have such a firm intuition that a non-zero Planck Constant makes the universe easier to simulate, especially in light of the hacks and optimizations that Bostrom describes. However, I'm still fond my insight -- perhaps true, perhaps even original -- that classical physics should allow in principle for infinite information density.
As a technologist, I tend to think there isn't an interesting possibility of our sort of physics being able to support a simulation of a universe of our sort of physics. The hacks and optimizations that Bostrom talks about -- monitoring a simulation to see what its inhabitants "notice" -- can be recognized as nigh-impossible by anyone who's tried to debug their own software (let alone the simulated mental operations of minds that nobody programmed).
So I think that element (2) -- simulations won't happen -- of Bostrom's disjunct is the most probable, but as a modal realist I already feel sort of like how I'd feel if I believed we were in a simulation.
From: Brian Holtz [mailto:email@example.com]
Sent: Wednesday, March 13, 2002 2:36 PM
Subject: anthropic reasoning re: "why is there something rather than nothing?"
down the rules of Life, gliders would still be a logical consequent of
certain possible configurations of the logically possible game of
Life. It has been proven that Life is rich enough to instantiate a
Turing machine, which are of course known to be able to compute
anything computable. So if mind is computable, consider a
configuration of Life that instantiates a Turing machine that
instantiates some mind.
Consider the particular Life configuration in which that mind
eventually comes to ask itself "why is there something instead of
nothing?". Even if in our universe no such Life configuration is ever
instantiated, that particular configuration would still be logically
possible, and the asking of the Big Why would still be a virtual event
in the logically possible universe of that Life configuration. The
epiphenomenal quality of that event for that logically possible mind
would surely be the same, regardless of whether our universe ever
actually ran that Life configuration. So the answer to that mind's Big
Why would be: because your existence is logically possible.
So pop up a level, and consider that you are that mind, and that your
universe too is just a (highly complex) logically possible state
machine. In that case, the answer to your Big Why would be the same.
Note that, while the Life thought experiment depends on mind being
computable, the logically possible universe (LPU) thought experiment
only assumes that our universe could be considered as a logically
possible sequence of (not necessarily finitely describable)
universe-states. The LPU hypothesis also depends on the thesis that
physicalism is right and that qualia and consciousness are
epiphenomena. The LPU hypothesis is of course unparsimonious (sort of
like the many-worlds interpretation of quantum theory), but parsimony
is perhaps inconsistent with *any* answer to the Big Why. The LPU
hypothesis is incompatible with strong free will (which itself may be
incoherent), but is compatible with weak free will (perhaps only if we
assume there are rules governing the transitions among
The idea that the world might be a dream is of course not new. But I
don't recall ever hearing that the world might be just a logically
possible dream for which no dreamer exists.
From: Nick Bostrom [mailto:firstname.lastname@example.org]
Sent: Wednesday, March 20, 2002 1:26 PM
To: Brian Holtz
Subject: Re: anthropic reasoning re: "why is there something rather than nothing?"
Hi. Two quick questions from someone who's enjoyed for several years your work on anthropic and transhumanist topics:
1. Has anyone ever applied anthropic reasoning to the perennial philosophical question of "why is there something rather than nothing?"?
Derek Parfit touched upon this topic in some lectures he gave in London a few years ago. There is also a mailing list, the everything-list, where this topic has been discussed extensively.
2. Has anyone ever noticed that Planck's Constant being non-zero (i.e. that our universe is quantum rather than classical) could be construed as evidence that our universe is a simulation?
Yes (I think Hans Moravec might have been first, but I'm not sure). My view (see the Simulation Argument paper) is that it is not good evidence for that because the apparent ultimate physics of our universe could easily be an illusion if we are living in a simulation. That is, our simulators could create the appearance that our physics is quantum or classical without actually having to go to the trouble of simulating our world down to such find detail.
All best wishes,