3 ms·

Optimizing black hole merger waveform calculations (Bluesky thread)

9 points by raattgift 3y ago

raattgift 3y ago
ETA: this gathers up the bluesky thread readably https://skyview.social/?url=https%3A%2F%2Fbsky.app%2Fprofile%2Fduetosymmetry.com%2Fpost%2F3knzeypktqz2x&viewtype=tree https://skyview.social/?url=https%3A%2F%2Fbsky.app%2Fprofile... although you'll probably prefer "unroll" over "tree" (but "tree" seems to capture everything including a handful of replies). Cross-posted to x/twitter: <https://twitter.com/duetosymmetry/status/1769913120099545488 https://twitter.com/duetosymmetry/status/1769913120099545488> (ETA: there are 38 (thirty eight) entries in the thread. Logged in on x/twitter I see them all, but bsky (logged in and not) sometimes doesn't show them all in one scroll-through. :/ ) tl;dr (it's a very technical explainer thread) [preliminary] this is physics, it is important to match GW (and optical) detections of mergers, not to model "spherical cows" [a] post-Newtonian (PN) methods are cheap to calculate for black hole binaries when they are far apart (and other methods are good for extreme mass ratios) but in the last moments before merger we need numerical relativity (NR). NR is expensive even on supercomputers. [b] PN and NR are different enough frameworks that knitting together the early inspiral PN and the late pre-merger NR requires some overlap and iteration. [c] results from a couple dozen simulations give interesting technical insights [d] orbital eccentricity (and ellipticity) make everything harder, especially for PN, because the plane of the orbit and the orientation of the black hole spins against the orbital plane all precess (and differently from each other) Finally, if you can't see the thread on either platform, the prerpint is at https://arxiv.org/abs/2403.10278 https://arxiv.org/abs/2403.10278 (I did double-check and can read the bsky thread via the Tor browser (obvs. not logged in). x/twitter is ... uncooperative when not logged in. Finally, mastodon threading is ... confusing.)
- semi-extrinsic 3y ago
  I find myself echoing the sentiment of Peter Woit - why on earth do people microblog technical stuff that would be infinitely nicer to read on a regular blog?
  - mionhe 3y ago
    Is there some amazing conversation happening there? I haven't seen it before, but I can't say I've been looking all that much.
  - BizarroLand 3y ago
    My guess is they go where their audience is instead of hoping their audience comes to them.

9 points by raattgift 3y ago

ETA: this gathers up the bluesky thread readably https://skyview.social/?url=https%3A%2F%2Fbsky.app%2Fprofile%2Fduetosymmetry.com%2Fpost%2F3knzeypktqz2x&viewtype=tree https://skyview.social/?url=https%3A%2F%2Fbsky.app%2Fprofile... although you'll probably prefer "unroll" over "tree" (but "tree" seems to capture everything including a handful of replies). Cross-posted to x/twitter: <https://twitter.com/duetosymmetry/status/1769913120099545488 https://twitter.com/duetosymmetry/status/1769913120099545488> (ETA: there are 38 (thirty eight) entries in the thread. Logged in on x/twitter I see them all, but bsky (logged in and not) sometimes doesn't show them all in one scroll-through. :/ ) tl;dr (it's a very technical explainer thread) [preliminary] this is physics, it is important to match GW (and optical) detections of mergers, not to model "spherical cows" [a] post-Newtonian (PN) methods are cheap to calculate for black hole binaries when they are far apart (and other methods are good for extreme mass ratios) but in the last moments before merger we need numerical relativity (NR). NR is expensive even on supercomputers. [b] PN and NR are different enough frameworks that knitting together the early inspiral PN and the late pre-merger NR requires some overlap and iteration. [c] results from a couple dozen simulations give interesting technical insights [d] orbital eccentricity (and ellipticity) make everything harder, especially for PN, because the plane of the orbit and the orientation of the black hole spins against the orbital plane all precess (and differently from each other) Finally, if you can't see the thread on either platform, the prerpint is at https://arxiv.org/abs/2403.10278 https://arxiv.org/abs/2403.10278 (I did double-check and can read the bsky thread via the Tor browser (obvs. not logged in). x/twitter is ... uncooperative when not logged in. Finally, mastodon threading is ... confusing.)

semi-extrinsic 3y ago
I find myself echoing the sentiment of Peter Woit - why on earth do people microblog technical stuff that would be infinitely nicer to read on a regular blog?
- mionhe 3y ago
  Is there some amazing conversation happening there? I haven't seen it before, but I can't say I've been looking all that much.
- BizarroLand 3y ago
  My guess is they go where their audience is instead of hoping their audience comes to them.