Show HN: Physically accurate black hole you can put in your room
by aplavin on 7/23/2026, 1:29:24 PM
We have a black hole at home — with actual relativistic physics, live in your browser.<p>I'm Sasha (Alexander) Plavin, an astrophysicist at Harvard's Black Hole Initiative studying quasars and black hole environments. I work with raytracing/radiative transfer simulations professionally, and wanted to make one anyone can play with — so I built this app.<p>Put 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 around the black hole, and special relativistic "Doppler boosting" changing brightness depending on the viewing angle — zoom out to see the fast jet where the latter effect is especially pronounced. Faint markers show where other viewers are standing right now.<p>Alternatively, put the black hole in front of your camera and watch it lens your actual surroundings. Light winds around the hole, so you see both what's in front of you and what's behind you at once (when the device and browser allow both camera feeds). The closer to the black hole, the stronger the bending — and the longer the light-travel delay: wave at it and watch the changes propagate inward. (unfortunately, WebXR restrictions make AR passthrough and the camera feed mutually exclusive)<p>No signup, basic features work on every device, no data uploaded — the camera feed never leaves your device. Source code: <a href="https://github.com/aplavin/blackhole.plav.in" rel="nofollow">https://github.com/aplavin/blackhole.plav.in</a>.<p>Enjoy having a black hole in your room, or use it for education/outreach — any questions, feedback, or suggestions are welcome!
Comments
by: dluan
I remember like 10 years ago when Occulus first came out there was that space simulation demo where you could go around the solar system in VR. You could also "fast travel" by zooming in towards a planet, moon, blackhole.<p>Yeah, that was the day I learned I have a deep, crippling phobia of large objects. And Melanoheliophobia, which is fear of black holes. The only other time I've felt that way was snorkeling once near a giant 3 story tall bait ball of swirling fish, which was so disorienting and panic inducing that I vomited.
7/27/2026, 2:54:08 AM
by: Waterluvian
It’s fascinating how things that were inverted seem to become corrected when I point this at the pre-existing black hole in my room.
7/27/2026, 1:52:47 AM
by: csmoak
Please correct me if I'm wrong, but it feels like the leading edge of the accretion disk (coming towards the viewer) should be significantly brighter than it is shown here, and the trailing edge (going away from) should be significantly dimmer?<p>Or could the brightness shown be a result of it being Kerr vs Schwarzschild?
7/27/2026, 2:58:27 AM
by: aizk
Very cool, and very mind bending. Very faithful to the Event Horizon Telescope rendering. A decade ago I got really into black holes for like a few months, and I read Kip Thorne's book called "The Science of Interstellar", talking all about black hole simulations. Have you read it? I wonder how the simulation tech has evolved, as 10 years is a lot. 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, tidbit somewhere.
7/27/2026, 2:09:51 AM
by: hahahaa
First time I have AR'd. That was cool. How does it keep the hole in the same point in space as I walk about?
7/27/2026, 1:49:50 AM
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7/27/2026, 1:40:58 AM
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7/27/2026, 1:45:25 AM
by: api
The singularity is near.
7/27/2026, 2:00:14 AM