Riviera Blog

We can examine the concept of simulism further, through the work of Edward Fredkin and Seth Lloyd (which I was introduced to by “Concevoir l’univers comme un ordinateur?”, an article by Jean-Paul Delahaye in Pour la Science No. 39, November 2006, in French). The argument is that it is likely that our universe can be digitally simulated since, as Fredkin alleges: at some scale, space and time are discrete and that the number of possible states of every finite volume of space-time is finite. (Fredkin 1992). That hypothesis has not yet been proven wrong, and so far every such question, discrete versus continuous, about a property of our world either remains undecided or it has been decided as discrete.). If it’s ever proven that indeed Nature is finite (and assuming the rules of physics are deterministic), then it will mean that the information contained in any region of space is finite, and its behaviour can be simulated by a cellular automaton, within a computer.

The problem with Fredkin’s hypothesis is that space-time is, as far as we’ve measured, anisotropic making the theory incompatible with special relativity, which states that space is actually isotropic and therefore it is impossible to divided it into a discrete grid. Until that problem is solved (and a few others too), it cannot be proven that the universe can’t be simulated by a digital simulation. (but it doesn’t rule out the more general brain-in-a-jar theory, which cannot disproved anyway — at least that’s the generally accepted opinion since Descartes.)

Friedkin, in his (unfinished) book Digital Mechanics, argues that there must be a preferred and accessible absolute reference frame, and that this doesn’t mean Einstein’s relativity is wrong, just misinterpreted. However, this reference frame has yet to be found. He adds: From an informational perspective, it is an absolute requirement that the single fixed reference system be accessible to everything that moves! There will be new and better experiments and we will find and measure it.. So while physicists are currently at work exploring the very very small, let’s hope that if space-time is discrete they will eventually find out. Yet, so far, there isn’t any proof of it.

Recently Seth LLoyd, in Programming The Universe, developed a more convincing theory, originally proposed by Feynman: quantum physics is a theory of information, and therefore the universe can be viewed as a big quantum calculation, currently running and computing its own future. In other terms, the laws of physics can be modelled by logical operations applied to qubits (quantum bits), showing that they can be seens as piece of software running on a quantum computer.

(footnote: Lloyd’s book is a great piece of work, and has made me understood much better the relationship between entropy and information. However I’ve failed to be convinced that the continuity of the universe can be reproduced by the continuity of wave functions in qubits. It must be properly demonstrated in the articles he refers to from the book, but I’m not familiar with the details of quantum theory to be confident to go and read them. So I guess I can only say that his books makes a somewhat convincing argument. Bah, I won’t let that stop me boldly writing nonsense.)

In the last few chapters, while Lloyd explores interesting consequences of this finding, it doesn’t strike him to ask: but if this is a computer program, isn’t it run by someone, just like I’m currently running the editor I’m typing this on? Seth, probably knows better and stops before entering metaphysical considerations that can’t be proven anyway. However, combined with the simulation argument, the idea of the universe-computer could somehow push us one step further into believing that we really are living inside a computer simulation.

And what’s possibly the most disturbing idea that comes out of all this is that as we progress towards understanding the rules that generated our universe-computer, we realise that those rules are actually fairly simple, and the computer itself may be run by a civilisation that’s not that alien to us. Not a meta-universe, made of hyperintelligent multidimensional beings whose simplest concepts could never be grasped by a human brain, but instead only a slightly more advanced world than ours, in which a kid is watching us running as the screen-saver of his advanced-world PC. And very soon he may well get bored, wiggle his advance-world mouse, and decide to play advanced-world Grand Theft Auto, instantly putting an end to us and everything we know!

Next: exploring virtual worlds.

[tags]simulism, quantum computers, edward fredkin, seth lloyd[/tags]