WEBVTT FILE ﻿1 00:00:10.260 --> 00:00:16.530 A black hole is a single point in space that has a lot of mass. One of the ways 2 00:00:16.530 --> 00:00:21.620 that we look for black holes is to develop new instruments 3 00:00:21.620 --> 00:00:25.560 and new technologies that can try to search for them. 4 00:00:30.300 --> 00:00:37.100 As we've observed black holes including the the supermassive black hole in the center of our galaxy, 5 00:00:39.280 --> 00:00:43.180 because it has such a strong gravity because it has lots of mass, 6 00:00:43.540 --> 00:00:46.540 stars will orbit black holes 7 00:00:46.740 --> 00:00:56.040 and as stars get closer and closer to the center of a black hole as it crosses over the Event Horizon, 8 00:00:56.340 --> 00:01:01.640 what will happen is that the material of these stars will get shredded apart, 9 00:01:02.180 --> 00:01:09.580 because the gravitational pull of a black hole is so strong that the material of the stars gets pulled apart. 10 00:01:11.220 --> 00:01:16.700 But there is an event horizon, which is the point at which the black hole's gravity 11 00:01:16.700 --> 00:01:20.220 starts to pull you so much that you can't escape. 12 00:01:20.720 --> 00:01:23.620 So as you approach the black hole, you'll feel its pull. 13 00:01:24.020 --> 00:01:29.852 But then as you get closer and closer and closer towards the event horizon, that's the point of no return so you couldn't 14 00:01:29.900 --> 00:01:30.720 escape past that. 15 00:01:32.340 --> 00:01:39.140 The easiest way to think of a black hole is just like anything that has mass so the Earth has mass 16 00:01:39.460 --> 00:01:43.460 And one of the reasons that the Moon orbits around the Earth 17 00:01:43.780 --> 00:01:50.480 is because the gravitational attraction of these two massive bodies. And so, Earth is distorting 18 00:01:50.900 --> 00:01:59.024 the space around the Moon and so that's what keeps the Moon in orbit. And so now take that to an extreme. So take 19 00:01:59.096 --> 00:02:01.900 something that's as massive as the Sun, 20 00:02:02.300 --> 00:02:06.700 or as massive as a million Suns and put it at a single point, 21 00:02:07.200 --> 00:02:14.200 and that distortion that you get is coming from that amount of mass in a single point. 22 00:02:19.160 --> 00:02:28.352 Black holes vary in size a lot. We know that black holes can be formed by massive stars exploding and then collapsing into 23 00:02:28.428 --> 00:02:29.860 the singular point. 24 00:02:30.140 --> 00:02:35.540 And those give us black holes that are about the mass of the Sun. So, those are solar mass black holes. 25 00:02:35.660 --> 00:02:40.960 However, we also know at the center of galaxies, like the Milky Way, 26 00:02:41.700 --> 00:02:47.100 there are supermassive black holes and these are millions or even billions of times the mass of the Sun. 27 00:02:47.280 --> 00:02:58.060 And how these form is actually a mystery. Studying black holes really gives us a fundamental insight 28 00:02:58.060 --> 00:03:01.580 into how gravity works because 29 00:03:01.720 --> 00:03:07.020 it's such a small physical scale, but it's a super massive object. 30 00:03:07.020 --> 00:03:11.100 And so understanding how black holes work and the 31 00:03:11.100 --> 00:03:18.261 interactions of black holes in other parts of the universe really give us a fundamental insight that we could then use to 32 00:03:18.331 --> 00:03:21.320 think about how our own solar system works. 33 00:03:22.180 --> 00:03:29.580 And so if we can understand how black holes work, they'll give us a key to really understanding our universe.