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https://arxiv.org/abs/2507.22950 https://arxiv.org/abs/2507.22950 Their argument is that quantum gravity can encode undecidable statements, and therefore canno
by mxkopy 11mo ago
https://arxiv.org/abs/2507.22950 https://arxiv.org/abs/2507.22950
Their argument is that quantum gravity can encode undecidable statements, and therefore cannot be completely computed. Of course take it with a grain of salt, since it relies on an incomplete and possibly inaccurate characterization of quantum gravity, something we don’t know anything about. Still, a cool idea.
- ameliaquining 11mo agoThe paper's core claim is wrong even before you get into any quantum gravity stuff. The other HN thread contains a number of comments explaining why.
- mxkopy 11mo agoIt seems like some of the dismissals are just summaries of basic decidability theory, which don’t attack the underlying argument of the paper: > …the idea that reality can tell us if a statement about a theory is true, given that the theory is an accurate description of reality. So if there’s an accurate Turing complete theory of reality, and we see some process that’s supposed to encode a decision on an undecidable statement being resolved (I guess in a non-probabilistic way as well), then we can conclude that reality is deciding undecidable statements in some nontrivial way. One of the stronger skeptics confidently claims that discrete phenomena doesn’t exist in quantum mechanics. I think there’s a bit of a cult of skepticism around this topic, which is usually fine, except when people haven’t read the paper or don’t have basic prerequisite knowledge before announcing their conclusions.
- deleted 11mo ago[deleted]
- recursivecaveat 11mo agoDo you necessarily need to compute anything in order to perform a simulation? Suppose whenever some weird undecidable statement quantum gravity situation comes up inside the simulation, you pause it, recreate the scenario on a lab bench, and then copy the data into your simulation. You didn't compute what would happen, you don't even necessarily understand how it works, but as long as its the same quantum gravity stuff inside and out, the simulation can proceed faithfully. This makes some assumptions about locality I guess. Of course the whole affair seems a little moot since you obviously only have to be accurate enough that it doesn't disrupt the ancestor simulation or whatever, but that's less fun to think about I suppose.
- mxkopy 11mo agoI think the distinction is a little semantic; the idea is that a simulation is anything that can be computed by Turing machine. So regardless of if we’re in a TM that’s being fed weird undecidable statements, the fact that they exist at all means at some level reality can’t be a TM. Contrast that with having undecidable processes that might go on forever, we could be in a TM and still have those. Basically simulation here means “is a TM”, not “is nested”.