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How Time Becomes Space Inside a Black Hole | Space Time

38 videos recommended on HN
YouTube
4 HN users recommended this explainer4 months2018–2025 score 4.5
Years with an HN recommendation, 2007–2026

Recommended as the cleanest visual explanation of time and space switching roles past the horizon, and a gateway to the channel's black hole videos.

A PBS Space Time episode explaining how space and time swap roles inside a black hole's event horizon. It is part of the channel's black hole series.

“I think this is the cleanest explanation with actual visual representation.” (HN, 2020)

1 strong recommendations · 3 recommendations · 3 citations · Explainers

7 Hacker News comments

From the HN archive; up to 20 kept per video, favoring different commenters. Recommendations first.

@pmiller2 Jul 2020 Recommends
on HN thread Astronomers claim to have seen the merger of two black holes within a third
> ...at the same moment. As an aside, this is a rather funny phrase to be using about objects so massive that time and space actually switch roles inside their event horizons compared to the normal universe. I don't feel like I can explain it very well, but here is a video that does so: [this video] (Skip to about 5:15 for the good stuff.)
Explains space and time swapping roles inside the event horizon.
@me_me_me Oct 2020 Recommends
on HN thread The Nobel Prize in Physics 2020
[link] I hope it helps. I think this is the cleanest explanation with actual visual representation. Edit: Sorry this one is even better. How Time Becomes Space Inside a Black Hole | Space Time [this video]
Clean visual explanation of space and time inside a black hole.

Citations, criticism and jokes

@dsnuh Oct 2018 Cites it
on HN thread Are Black Holes Actually Dark Energy Stars?
I just realized I was replying to the wrong parent comment! So sorry. I was talking about a PBS Space Time episode on YouTube I saw in (or came across via) a different comment. [this video]
PBS Space Time episode on black holes.
@zackmorris Apr 2022 Cites it
on HN thread What keeps earth from collapsing in on itself? (2010)
Read more
Apologies for replying to my own post, but I should have included sources. Here is the best stuff I've found so far: [link] [link] [link] There is an episode of How the Universe Works (I think) where they talk about the multiverse looking like an infinite block of swiss cheese, and each black hole having a child universe inside with its own physics, sealed off from the parent universes. So we're in the black hole where the rules of physics allow us to exist to realize it. In other words, the multiverse used black holes to evolve the rules of physics until consciousness could exist. It's another interpretation of the anthropic principle so isn't really testable, but I thought it was elegant. Wish I could find it. Edit: some places to start: [this video] [link]
Starting point for black hole reading.
@smolder May 2025 Cites it
on HN thread ALICE detects the conversion of lead into gold at the LHC
What happens inside a black hole is basically unknowable. We can only ponder the math which leads to ideas like space and time swapping roles once you cross the event horizon.[0] The only thing that comes out is hawking radiation, which is sort of like... half of nothing. [0] [this video]
Space and time swapping roles past the horizon.

Video list and Hacker News comment labels from HackerTube (prompted by @karpathy), released under ODC-By 1.0, built on the open-index/hacker-news archive. Hacker News data is provided by Y Combinator; comments remain the work of their authors. Video titles, channel names and thumbnails belong to their creators and are shown via YouTube. HackerTube Watch is an unofficial edition. Data export of 2026-10-31.

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