{"schema":"pubphys.bundle/1","record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"cae127955486402570a35fb149d0f7a17de6002ebe62ea833d15ac8359588c3e","created":"2026-10-15T23:43:22Z","files":[],"origin":{"assisted_by":["ai:gpt-5.5"],"kind":"seed"},"parents":["625b3a0b0ff6e29656446e369ecb0e88f1bf08a229b045dbaf283f8c2666876b","ce59fb6cd812fc05906d0c60a71c75ea22bc686bcf38e7c3ef7010834d98ee7b"],"salt":"58745fd23f9347403ddcdf83a4acccaf0e4995fecd1a311670a3e8d60d717757","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"value","assisted_by":["ai:gpt-5.5"],"external_id":"grav.analog-hawking.analog-backreaction","kind":"well-posed","literature_status":"partially-resolved","n":"2","parents":[],"plain":"A real black hole should shrink as it radiates; in a condensate the emitted sound should likewise change the flow that makes the horizon. Theory now predicts how much the flow is changed, but no experiment has measured the change.","posed_since":"","precise":"For a quasi-1D BEC sonic black hole, the back-reaction of the Hawking flux on the flow, to first order in the quantum depletion 1/(n_1D $\\xi$) (n_1D the linear density, $\\xi$ the healing length), has been computed as a stationary shift of the density, velocity and Mach-number profiles. Determine whether the surface gravity $\\kappa$ also drifts in time (sign and rate of $\\mathrm{d}\\kappa/\\mathrm{d}t$, and whether the evolution follows an evaporation law analogous to $\\mathrm{d}M/\\mathrm{d}t$ proportional to $-T_H^2$), and measure the predicted stationary or time-dependent profile change. An answer is a measured profile change that agrees with the computed one after three-body loss, heating and stimulated emission are subtracted.","problem_ref":"625b3a0b0ff6e29656446e369ecb0e88f1bf08a229b045dbaf283f8c2666876b","references":"","settled_by":"A measurement of the density, velocity or Mach-number profile change in a stationary BEC analog that matches the computed back-reaction after atom loss and heating are subtracted.","status_note":"Back-reaction equations were derived (Liberati, Tricella, Trombettoni 2020; Balbinot, Fabbri, Ciliberto, Pavloff 2025), and Ciliberto et al. (PRA 112, 063323, 2025) computed a stationary Mach-number shift; no measurement has isolated the effect as of 2026.","title":"How does Hawking emission change the analog horizon that produces 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