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Cellular automata violate continuity and isotropy, which means they're inconsistent with the continuous spatial formalism used in special relativity, general re
by aphyr 13y ago
Cellular automata violate continuity and isotropy, which means they're inconsistent with the continuous spatial formalism used in special relativity, general relativity, classical electrodynamics, and as far as I know, quantum electrodynamics. We have no experimental evidence inconsistent with continuous models of space. We also have evidence that Lorentz symmetry holds over scales smaller than the Planck length, which suggests spacetime is not quantized.
One of the problems with quantized spacetime is that the cells would have a size--and sizes change depending on your velocity. Were spacetime to be comprised of cells, you'd be able to establish a single, most privileged reference frame--and that doesn't sit well with the principles of relativity.
That said, we really don't have good models for what happens at small spacetime scales yet. Gravity is poorly understood. Theories change as new evidence and mathematics develop. I just wouldn't trust Wolfram's opinion without either a.) experimental evidence or b.) a model which is consistent with (or radically reformulates) significant parts of relativity and quantum electrodynamics.
- aphyr 13y agoAh, here we go. Aaronson 2002 shows that Wolfram's model cannot be consistent with experimental evidence: In physics, we examine Wolfram's proposal for a deterministic model underlying quantum mechanics, with 'long-range threads' to connect entangled particles. We show that this proposal cannot be made compatible with both special relativity and Bell inequality violation. http://arxiv.org/abs/quant-ph/0206089 http://arxiv.org/abs/quant-ph/0206089
- 3rd3 13y agoFor some interesting reads: Just take a look at the summaries, introductions and conclusions in Aaronson’s publications.
- tokipin 13y agoI want to point out that Wolfram doesn't think the universe is a giant cellular automaton. He gives CA as examples of how easy it is to produce impermeable complexity. His more serious proposal is a graph-based system, though I haven't perused enough to know if that's also for the sake of example or if it's intended to be taken as a serious physical theory. Most likely it's an earnest attempt at a heuristic towards the goal of, in his terminology, "finding the program of the universe."
- robotresearcher 13y agoA CA is a graph-based system.
- chinpokomon 13y agoThanks, you've given me some more topics to research.