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2022-01-27: How Does Gravity Escape A Black Hole?

  • 10:19: ... for those of you who love their Penrose diagrams, just think about the source of the gravitational field as always being ...

2020-06-15: What Happens After the Universe Ends?

  • 09:34: ... of the other things Roger Penrose is famous for is his Penrose diagrams - these are ways of mathematically transforming our grid of spacetime to ...

2020-05-18: Mapping the Multiverse

  • 00:02: Or in physics-ese, it’s the maximally extended Penrose diagram of a Kerr spacetime.
  • 03:41: As we take this journey we’re also going to plot our path on the Penrose diagram.
  • 11:21: The complete Penrose diagram for the Kerr spacetime has not one, but two inner event horizons leading to two parallel wormholes.

2020-03-31: What’s On The Other Side Of A Black Hole?

  • 04:31: ... coordinates are even more popular for intergalactic travelers. On Penrose diagrams, space and time also bunch up at infinite distance so tha t the entire ...
  • 05:00: ... is at true singularities, like at the center of the black hole. On our Penrose diagram, we see that light rays can either travel away from the black hole to ...
  • 05:49: ... say this Penrose diagram is geodesically incomplete because there are light rays with undefined ...

2019-04-03: The Edge of an Infinite Universe

  • 05:19: ... the early 60s he developed his Penrose coordinates and Penrose diagrams – also known as Penrose-Carter diagrams, for Brandon Carter who came up ...
  • 06:16: ... amazing thing about the Penrose diagram is that the transformation preserves all internal angles – all angles ...
  • 07:44: ... Penrose diagrams represent a universe that is “asymptotically flat” – it may have some ...
  • 09:09: Penrose diagrams define the infinite boundary of a flat universe as a useful tool in calculation.
  • 09:29: Just like the Penrose diagram we’ll do a conformal transformation – all internal angles preserved, and will compactify layers towards the edge.

2018-06-20: The Black Hole Information Paradox

  • 12:52: EpsilonJ asked, what would happen if you fired a continuous beam of electrons at a black hole and how would the charge affect the Penrose diagram?
  • 13:11: And it turns out that a charged black hole has a pretty weird Penrose diagram.

2017-08-30: White Holes

  • 04:34: To really understand what this eternal black hole looks like, we're going to need to use a tool that we've already played with, that Penrose diagram.
  • 04:42: To refresh your memory, in a Penrose diagram, the x and y-axes are redefined from space and time to merge space and time into new coordinates.
  • 06:44: We can make some sense of the behavior of this strange region by using the Penrose diagram.
  • 11:25: But speaking of other universes, it turns out that we haven't finished building our Penrose diagram yet.

2017-03-29: How Time Becomes Space Inside a Black Hole

  • 06:28: Close to and within the black hole, the Penrose diagram is much more useful.

2017-01-04: How to See Black Holes + Kugelblitz Challenge Answer

  • 05:55: I also asked you to draw a Penrose diagram to justify your choice.
  • 06:02: In the challenge question, I showed you the Penrose diagram for a star collapsing into a black hole.
  • 06:10: I'm drawing only the right part of the usual Penrose diagram here.
  • 06:41: On the Penrose diagram, that horizon extends both forwards and backwards in time.
  • 07:17: That shell takes a 45-degree path, as do all light speed things on the Penrose diagram.
  • 08:11: First, the Penrose diagram for Project Disco Ball.
  • 09:01: ... on the Penrose diagram, that's seen as the future light cone of everything below the event ...

2016-12-21: Have They Seen Us?

  • 15:54: You know, there's probably a Penrose diagram for this.

2016-12-14: Escape The Kugelblitz Challenge

  • 00:11: This is the Penrose diagram.
  • 00:27: The Penrose diagram allows us to easily understand the limits of our access to this universe.
  • 00:44: ... we are going to use the Penrose diagram to look at the difference between the idealized, theoretical black hole ...
  • 01:11: The Penrose diagram we looked at represents a Schwarchild black hole-- so no electric charge and no rotation, but also an eternal black hole.
  • 01:42: So what does this look like on a Penrose diagram?
  • 02:40: Outside the black hole, the event horizon becomes the new edge of the universe on our Penrose diagram.
  • 03:27: On the Penrose diagram, we should extend our effective event horizon backwards to include that space.
  • 07:19: The president is especially upset, so draw a nice Penrose diagram of the situation to show why your preferred plan has the best shot.

2016-12-08: What Happens at the Event Horizon?

  • 02:01: The tool that will answer these questions is called the Penrose diagram, sometimes also the Carter Penrose diagram.
  • 04:04: And this is where the Penrose diagram comes in.
  • 04:42: This is the Penrose diagram for flat space-time with no black holes.
  • 05:56: The future cosmic horizon on the Penrose diagram is replaced with a plunge into a black hole.
  • 07:01: Now that we've nailed the Penrose diagram, we can use it to do some serious black hole monkey physics.
  • 10:43: For example, I only showed you half of the Penrose diagram.
  • 11:19: Then our Penrose diagram blooms outwards to include potentially infinite parallel regions of space-time.
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