Dissolving an Event Horizon

**SPEAKER_1** (0:00)
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**SPEAKER_2** (0:30)
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**SPEAKER_3** (0:31)
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**SPEAKER_4** (0:32)
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**SPEAKER_4** (0:51)
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**Matt O'Dowd** (1:00)
Black hole singularities break physics. Fortunately, the universe seems to conspire to protect itself from their causality-destroying madness. At least, so says the cosmic censorship hypothesis. Only problem is that many physicists are coming to think that might be wrong, and that naked singularities may exist after all.
Strange things happen inside black holes. Space and time switch roles, pathways open to other universes, and in some cases, time travel becomes possible. Causality breaks down. And so the supreme sensibleness of physics is badly threatened. And surrounding all of this weirdness is the event horizon. The surface around the central singularity, where the inward flow of space reaches the speed of light, and time freezes from the perspective of the outside universe. In the most real possible sense, the interior of the black hole is its own separate space-time, excised from our universe. The event horizon sounds dire, but it's a blessing. Without it, the infinitely dense singularity and its surrounding madness is exposed to the outside universe. We would have what we call a naked singularity. This would wreak havoc on our understanding of causality, and our precious laws of physics would become unhinged. Given the dire consequences, Roger Penrose proposed the Cosmic Censorship Hypothesis, which basically states that every gravitational singularity must be surrounded by an event horizon. In an upcoming episode, we're going to look deeper at why many physicists believe the Cosmic Censorship Hypothesis must be true, even without knowing exactly why it's true, and we'll see why other physicists have begun to doubt its validity.
But today we're going to look at the astrophysics, and see how exactly a naked singularity might be formed in the first place, and how the universe seems to work very hard to protect itself from them. So, let's talk about how to dissolve an event horizon. Although I would ask you to please not try this at home, for the sake of all of physics.
According to the so-called no-hair theorem, black holes can have only three properties– mass, electric charge and spin. Mass is what makes a black hole a black hole, and so the simplest black holes have only this property. These are Schwarzschild black holes. And with only mass, that means they also have inward-pulling gravity. With nothing to counter the inward flow of space, an event horizon is inevitable. In recent episodes, we also explored the rotating or Kerr black hole.
Inside, we found that the rapid rotation has…

**SPEAKER_4** (4:01)
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**Paris Hilton** (4:26)
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