{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"2918366340ef2b8d35bfcbf5c05253807b587f95de83c9726f4e00b6db39317c","created":"2026-10-03T07:18:08Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["5475cf5dc5b1a72283d26dc95dc6e00d7ea4e00096a7c6492e409a1816eeb011"],"salt":"bac3b0fcf14d9d062076cd59e0b4985b246ce6a3119bfd4045dad727af88db46","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"mechanism","assisted_by":[],"external_id":"plasma.reconnection.collisionless-rate","kind":"phenomenon","literature_status":"partially-resolved","n":"1","parents":[],"plain":"Computer simulations and spacecraft find that reconnection without particle collisions always proceeds at about one tenth of a natural speed limit. Nobody has a derivation that explains why this number is so universal.","posed_since":"","precise":"In collisionless electron-ion reconnection (realistic $m_i/m_e$, guide field $B_g/B_0$ from 0 to above 1, plasma $\\beta\\ 0.01\\ \\text{to}\\ 1$, symmetric and asymmetric inflows), the normalized rate $E_{\\mathrm{rec}} c/(B_0 v_A)$ is about 0.1 in kinetic simulations and MMS data, nearly independent of the dissipation mechanism. Derive from first principles the mechanism that selects this value and its dependence on $B_g/B_0,\\beta$ and inflow asymmetry in 2D and 3D. An answer is a derived formula that matches fully kinetic simulations to within 20 percent across these parameters.","problem_ref":null,"references":"","settled_by":"A first-principles theory whose predicted rate and parameter dependences agree with large 3D particle-in-cell scans and MMS event statistics.","status_note":"A 2017 geometric argument (Liu et al., PRL 118, 085101) bounds the local rate near 0.1, but whether it is the selection mechanism, especially in 3D, is still debated.","title":"Why the collisionless reconnection rate is close to 0.1","topic_ref":"c1057caf785ec309864fe9c3911636cf72981d9ad70fccb8c56b4c4d20d44a4f"},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"0ffe382e5decb503de20a3969ad4a07c245b0f452541481b5ea519d69e2e6fa8","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"25f59ca37dc7124f3ddd542ca10fe1b04bed555d3b82b0cdd55994c81fdd3057","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"t5aAEgzdjnZajzQ51733EPgpMAJ4cUBfCEcDcMYkTBInCm8eC9IrW2dPml3N-lyxa9F5VJLaV35SnGLxM0EACA"},"schema":"pubphys.envelope/1"},"record_hash":"0ffe382e5decb503de20a3969ad4a07c245b0f452541481b5ea519d69e2e6fa8","leaf_index":1858}