What would happen if a magnetar collided with a black hole?
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00:00 In the center of our galaxy,
00:03 the Milky Way,
00:04 there is a supermassive black hole
00:07 feeding on nearby stars.
00:10 It's called Sagittarius A*.
00:13 And if a giant gravitational monster
00:17 slowly eating the galaxy
00:18 isn't terrifying enough,
00:20 there's another cosmic monstrosity
00:23 lurking around it.
00:26 Is it possible that one day
00:27 they would get a little too close
00:29 and collapse on each other?
00:31 What would be left of the Milky Way
00:33 if they did?
00:35 Would there be even a slight chance
00:38 that the Earth could get out of that safely?
00:41 This is WHAT IF,
00:43 and here's what would happen
00:45 if a magnetar collided with a black hole.
00:51 This monstrosity creeping through the Milky Way
00:55 is a remnant of a giant exploded star.
00:58 But it's not just any remnant.
01:00 It's an extremely dense
01:02 and very magnetic collapsed stellar core,
01:06 a magnetar.
01:09 Let me refresh your knowledge of magnetars.
01:12 They're born when a star,
01:14 at least eight times more massive than our Sun,
01:18 reaches its expiration date
01:20 and explodes in a beautiful supernova.
01:23 Much of that star is gone,
01:25 but the dense core of it remains.
01:28 Most of these remnants become neutron stars.
01:31 They spin very fast,
01:33 usually a few times per second,
01:36 and they're composed of neutrons.
01:39 Some neutron stars have such strong magnetic fields
01:42 that they emit electromagnetic radiation
01:45 from their poles.
01:46 That makes them pulsars,
01:48 and you can observe them with a telescope
01:50 when their poles face the Earth.
01:53 Only a few pulsars develop such an extremely
01:56 powerful magnetic field.
01:58 They become the strongest magnets in the Universe,
02:02 the magnetars.
02:05 They spin once every 10 seconds,
02:07 but their magnetic field is 100 times stronger
02:11 than that of a neutron star.
02:13 If one of those magnets came halfway between
02:16 the Moon and the Earth,
02:18 well, it wouldn't be pretty.
02:22 But would it be as bad from a distance
02:25 of 26 light-years away?
02:28 What I'd like to know is,
02:30 would a magnetar swallow a black hole,
02:32 or would a black hole gobble up a magnetar?
02:36 The collision of these two giants
02:40 wouldn't end up in an explosion,
02:41 but in a quiet cosmic merger,
02:44 stretched over billions of years.
02:48 Although magnetars are incredibly powerful,
02:51 they would lose the battle with a black hole.
02:55 Depending on the trajectory of the magnetar,
02:58 as well as the size and mass
03:00 of both the magnetar and the black hole,
03:03 the magnetic monster would be eaten up
03:05 either whole or slowly, piece by piece.
03:10 As the magnetar was being torn apart by the black hole,
03:14 it would be sending gravitational waves
03:16 throughout the Universe,
03:18 disturbing the curvature of spacetime.
03:21 Once the black hole consumed the magnetar,
03:24 its mass would increase
03:26 and expand its event horizon.
03:28 And thanks to this expansion,
03:31 more and more stars would be flung
03:33 into its dark density.
03:35 The black hole would be slowly eating our galaxy,
03:39 star by star.
03:42 Eventually, after quadrillions of years
03:44 of star consumption,
03:46 the black hole could gobble up the Milky Way.
03:50 All of it.
03:52 By that time, humanity would most likely be long gone anyway.
03:57 That is, unless another cosmic event
03:59 disrupts this feast
04:01 some 4.5 billion years from now.
04:05 But that's a story for another WHAT IF.
04:09 (upbeat music)
04:11 (dramatic music)