[{"data":1,"prerenderedAt":724},["ShallowReactive",2],{"project-49021270":3},{"id":4,"name":5,"line":6,"line_source":7,"title":8,"url":9,"domain":5,"maker":10,"posted_at":11,"year":12,"points":13,"comments":14,"rank_in_year":15,"shown_in_year":16,"top":17,"tier":18,"category":19,"subcategory":20,"format":21,"keywords":22,"reception":28,"sentiment":29,"stance_mix":30,"scored_comments":35,"aspects":36,"strip":46,"post_text":48,"what":49,"said":81,"maker_in_thread":153,"shape":163,"grid":168,"attempts":685,"same_week":686,"maker_shows":33,"maker_hidden":716,"reader_version":717,"card":718},"49021270","blackhole.plav.in","Physically accurate black hole you can put in your room","title","Show HN: Physically accurate black hole you can put in your room","https:\u002F\u002Fblackhole.plav.in","aplavin",1784813364,2026,477,193,57,4366,2,"legend","learning_science","black hole visualization","web_app",[23,24,25,26,27],"black hole simulation","relativistic raytracing","gravitational lensing","webxr","astrophysics visualization","debated",0.132,{"positive":31,"neutral":32,"mixed":33,"critical":34},17,25,1,20,63,{"execution":37,"docs":40,"idea":42,"design":44,"performance":45},{"positive":38,"critical":39},4,5,{"positive":41,"critical":17},0,{"positive":43,"critical":17},6,{"positive":33,"critical":43},{"positive":33,"critical":41},[38,47,41,33,17,47,33,47,39,33,33,47,38,41,41,47,41,41,41,41,47,41,41,47,39,33,47,17,38,39,41,41,47,47,33,33,33,39,47,38],3,"We have a black hole at home — with actual relativistic physics, live in your browser.\n\nI'm Sasha (Alexander) Plavin, an astrophysicist at Harvard's Black Hole Initiative studying quasars and black hole environments. I work with raytracing\u002Fradiative transfer simulations professionally, and wanted to make one anyone can play with — so I built this app.\n\nPut the black hole onto your screen (any browser), or directly into your room with AR or VR (requires WebXR, for example Chrome on Android, or any VR headset). When looking around, pay attention to unintuitive relativistic effects: rays bending ",{"problem":50,"audience":56,"pricing":60,"motivation":61,"time_to_build":60,"stack":65,"openness":78,"stage":79,"team_size":80},{"value":51,"source":52,"evidence":53},"Lets people explore black hole light bending and relativistic effects interactively.","maker",[54],{"id":55},"post",{"value":57,"source":52,"evidence":58},"General public, students and science outreach audiences.",[59],{"id":55},null,{"value":62,"source":52,"evidence":63},"Make black hole physics accessible for education and outreach.",[64],{"id":55},[66,70],{"value":67,"source":52,"evidence":68},"WebXR",[69],{"id":55},{"value":71,"source":72,"evidence":73},"GLSL fragment shaders (raymarch.frag)","commenter",[74],{"id":75,"by":76,"text":77},"49065148","20k","If anyone's interested in the accuracy, this is very 'visualisation grade' software. Its a bit of a pet peeve of mine that people present these sims as being very physically…","open_source","launched","unknown",{"praise":82,"objections":90,"requests":103,"questions":123,"alternatives":136},[83],{"value":84,"source":72,"evidence":85},"Cool use of WebXR",[86],{"id":87,"by":88,"text":89},"49107845","utopiah","Very cool use of WebXR!",[91,95,99],{"value":92,"source":72,"evidence":93},"Colormap and disk color are arbitrary, so not physically accurate.",[94],{"id":75,"by":76,"text":77},{"value":96,"source":72,"evidence":97},"Simplified radiative transfer and Doppler formula are inaccurate.",[98],{"id":75,"by":76,"text":77},{"value":100,"source":72,"evidence":101},"Non-rotating black hole by default.",[102],{"id":75,"by":76,"text":77},[104,114],{"value":105,"source":72,"evidence":106},"Support rotating (Kerr) black holes by default.",[107,111],{"id":108,"by":109,"text":110},"49065861","EugeneOZ","“Physically accurate” indeed raises the bar significantly. You’ve already done great work here. That said, the feedback seems to come from someone who spent considerable time…",{"id":112,"by":10,"text":113},"49069036","Sure, most of the raised questions are reasonable potential feature additions to be made – things like rotating black holes, or linear brightness-to-screen-pixel mapping. They…",{"value":115,"source":72,"evidence":116},"Linear brightness-to-pixel mapping mode.",[117,120],{"id":118,"by":76,"text":119},"49065760","Yeah the doppler in this picture is all wrong unfortunately, the underlying equation used isn't right here (they mixed up spectral radiance and radiant flux). The rendering is…",{"id":121,"by":10,"text":122},"49072755","> What exactly is physically accurate here though? I'll assume this is a good faith question, hope it was intended like one. I view strong light bending as the key distinguishing…",[124,130],{"value":125,"source":72,"evidence":126},"How the black hole would look in a room and its mass estimate.",[127],{"id":128,"by":10,"text":129},"49163326","> I do wonder if you do like, size estimates of a black hole in my room. Suppose I have a black hole in my room, I'd be curious to know what the mass of that is, like a fun fact,…",{"value":131,"source":72,"evidence":132},"Why camera mode and AR cannot be combined.",[133],{"id":134,"by":10,"text":135},"49068947","Yes, as said in the text, unfortunately this is a limitation of browser APIs. You either get AR and no access to the camera feed (this is the AR mode here, black hole floating in…",[137,143,147],{"value":138,"source":72,"evidence":139},"Luminet's 1979 black hole simulation",[140],{"id":141,"by":10,"text":142},"49065074","The technology has come a long way indeed! The first simulations of how a black hole would look like are from 1979, by Jean-Pierre Luminet – take some time to find and look at…",{"value":144,"source":72,"evidence":145},"Interstellar visualization",[146],{"id":75,"by":76,"text":77},{"value":148,"source":72,"evidence":149},"Dominic Chang's black hole camera filter",[150],{"id":151,"by":10,"text":152},"49065477","Yes, linked in the readme! They simulate light bending, but ignore time delay effects. I think the earliest of these black-hole-camera renderings is…",{"comments":154,"answered":31,"key":155},37,[156,159,162],{"id":157,"text":158},"49065219","Some are fair – of course this is a simplified visualization! Observationally, we don't really know how fast a given black hole is rotating, and here I indeed assumed a…",{"id":160,"text":161},"49065452","> Its titled a \"physically accurate black hole\"! Please don't do this, if its intentionally not physically accurate and heavily simplified! It also doesn't exert the gravity 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