The world problem: on the computability of the topology of 4-manifolds · HackerPapers discussionshttps://hackerpaper.kaipfister.de/p/gr-qc_0506019/Collected HN comments and submissions linking this paper.enMon, 02 Nov 2026 11:16:22 GMTThe world problem: on the computability of the topology of 4-manifolds — mentioned by whatshisfacehttps://news.ycombinator.com/item?id=26747063urn:hackerpapers:mention:gr-qc_0506019:26747063Fri, 09 Apr 2021 05:38:45 GMT<p>If what is suspected is true, then yes, strong Church-Turing is false. If there&#x27;s a symmetry in QCD that makes simulation possible in polynomial time, i.e. a helpful property that is true of QCD specifically but absent from the more general class of integrals its solutions belong to, then no. If you&#x27;re looking for something to raise your hair even farther, some suspect that gravity is outright uncomputable[0] due to the unclassifiability of 4-manifolds and the expectation that quantum gravity will require summing over possible spacetimes. Since all of our computers are built with QED, it…</p><p><a href="https://hackerpaper.kaipfister.de/p/gr-qc_0506019/">Paper and discussion history</a>. A mention is not an endorsement.</p>gr-qc