Saturday, March 18, 2006

What if our Universe was a Reality Simulation?

Found this topic on David Brin's blog. The original posting is the Sunday, March 12, 2006 entry on fourmilog and Walker, the author, comes out in favor of Intelligent Design should our Universe be a simulation.
"What would we expect to see if we inhabited a simulation? Well, there would probably be a discrete time step and granularity in position fixed by the time and position resolution of the simulation—check, and check: the Planck time and distance appear to behave this way in our universe. There would probably be an absolute speed limit to constrain the extent we could directly explore and impose a locality constraint on propagating updates throughout the simulation—check: speed of light. There would be a limit on the extent of the universe we could observe—check: the Hubble radius is an absolute horizon we cannot penetrate, and the last scattering surface of the cosmic background radiation limits electromagnetic observation to a still smaller radius. There would be a limit on the accuracy of physical measurements due to the finite precision of the computation in the simulation—check: Heisenberg uncertainty principle—and, as in games, randomness would be used as a fudge when precision limits were hit—check: quantum mechanics.

Might we expect surprises as we subject our simulated universe to ever more precise scrutiny, perhaps even astonishing the being which programmed it with our cunning and deviousness (as the author of any software package has experienced at the hands of real-world users)? Who knows, we might run into round-off errors which “hit us like a ton of bricks”! Suppose there were some quantity, say, that was supposed to be exactly zero but, if you went and actually measured the geometry way out there near the edge and crunched the numbers, you found out it differed from zero in the 120th decimal place. Why, you might be as shocked as the naïve Perl programmer who ran the program “printf("%.18f", 0.2)” and was aghast when it printed “0.200000000000000011” until somebody explained that with about 56 bits of mantissa in IEEE double precision floating point, you only get about 17 decimal digits (log10 256) of precision. So, what does a round-off in the 120th digit imply? Not Theory 2, with its infinite number of infinitely reproducing infinite universes, but simply that our Theory 1 intelligent designer used 400 bit numbers (log2 10120) in the simulation and didn't count on our noticing—remember you heard it here first, and if pointing this out causes the simulation to be turned off, sorry about that, folks! Surprises from future experiments which would be suggestive (though not probative) that we're in a simulated universe would include failure to find any experimental signature of quantum gravity (general relativity could be classical in the simulation, since potential conflicts with quantum mechanics would be hidden behind event horizons in the present-day universe, and extrapolating backward to the big bang would be meaningless if the simulation were started at a later stage, say at the time of big bang nucleosynthesis), and discovery of limits on the ability to superpose wave functions for quantum computation which could result from limited precision in the simulation as opposed to the continuous complex values assumed by quantum mechanics. An interesting theoretical program would be to investigate feasible experiments which, by magnifying physical effects similar to proposed searches for quantum gravity signals, would detect round-off errors of magnitude comparable to the cosmological constant. "
John Walker (Autodesk founder)
Comments:
Whoa... can somebody say all that again, but use different words??

Chances are if I read it slowly a couple times I'll be okay. But still. My goodness! Amusing that this is the founder of Autodesk - I spend 30-40 hours a week using one of their products.
 
Planck Units are units of measure to describe the Universe we live in. They are limits in a sense. You can read about them here: http://en.wikipedia.org/wiki/Planck_units We can only measure time as far as Planck time. We can only measure length as small as Planck length. In any simulation, you have initial conditions or limits. You might also have a random number generator to introduce randomness into your model (random molecular motion, say). So, Planck Units are initial limits or boundaries. Quantum mechanics are dice (random number generator). Then you start your Universe and Everything program running and see what happens.

However, I was thinking about this after I awoke. You'd need perfect hardware, perfect software, perfect power and lots and lots of it to run a simulation he is positing. What happens when you get a power spike or a floating point number rounds off funny? Add to it that no one knows what Consciousness is or how it works or even what it's doing and you can see that it is just a nice thought experiment.

The Truth is more profound and sacred than we can imagine. I believe that this Universe is God's playground in a sense (Tolle calls the Universe God's Body), although I think virtual reality computer game pales as a description to what we live, interact and play in.
 
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