Show HN: Physically accurate black hole you can put in your room

Show HN: Physically accurate black hole you can put in your room(blackhole.plav.in)

60 points by aplavin 3 days ago | 10 comments

We have a black hole at home — with actual relativistic physics, live in your browser.

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.

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.

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)

No signup, basic features work on every device, no data uploaded — the camera feed never leaves your device. Source code: https://github.com/aplavin/blackhole.plav.in.

Enjoy having a black hole in your room, or use it for education/outreach — any questions, feedback, or suggestions are welcome!

Waterluvian 1 hour ago |

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.

aizk 55 minutes ago |

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.

hahahaa 1 hour ago |

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?

dmd 1 hour ago | |

The app doesn't have to do this itself, phones do it for you. ARCore on Android, ARKit on iOS.

hahahaa 1 hour ago | | |

Oh yeah I mean how do the phones do that. I guess it uses dead reckoning with visual cues and some machine learning.

api 1 hour ago |

The singularity is near.