1 00:00:04,120 --> 00:00:07,160 Speaker 1: Get in touch with technology with tech Stuff from how 2 00:00:07,200 --> 00:00:14,000 Speaker 1: stuff Works dot com. Hey everybody, and welcome to tech Stuff. 3 00:00:14,040 --> 00:00:16,680 Speaker 1: I'm your host, Jonathan Strickland. I'm an executive producer with 4 00:00:16,720 --> 00:00:18,599 Speaker 1: How Stuff Works in my Heart Radio, and I love 5 00:00:18,840 --> 00:00:24,000 Speaker 1: all things tech. If you're wondering why I said it 6 00:00:24,000 --> 00:00:26,080 Speaker 1: that way, is because I was watching my producer Tari, 7 00:00:26,160 --> 00:00:28,520 Speaker 1: who likes to try and lip sync as I do 8 00:00:28,640 --> 00:00:30,840 Speaker 1: my intro, and sometimes I tried to throw her off 9 00:00:30,880 --> 00:00:33,120 Speaker 1: on purpose. And you, guys, get to enjoy the fruits 10 00:00:33,159 --> 00:00:35,680 Speaker 1: of my labor. You also are going to get to 11 00:00:35,760 --> 00:00:38,680 Speaker 1: enjoy a classic episode of tech Stuff because I'm still 12 00:00:38,720 --> 00:00:42,839 Speaker 1: on vacation and by now I'm sure I'm deep in 13 00:00:42,840 --> 00:00:47,839 Speaker 1: Harry Potter World probably, So this classic episode is all 14 00:00:47,920 --> 00:00:53,440 Speaker 1: about Howlego works. This was the facility that detected gravitational 15 00:00:53,479 --> 00:00:57,160 Speaker 1: waves a few years ago, which was a big, big 16 00:00:57,200 --> 00:01:01,000 Speaker 1: deal in the science world. It went from talking about 17 00:01:01,080 --> 00:01:06,839 Speaker 1: a hypothetical effect to detecting said hypothetical effect does proving 18 00:01:06,880 --> 00:01:09,880 Speaker 1: it's not just hypothetical. So I hope you enjoy this 19 00:01:09,959 --> 00:01:15,199 Speaker 1: classic episode. The Ligo Observatory had picked up a gravitational wave, 20 00:01:16,040 --> 00:01:20,040 Speaker 1: and this was huge news around the world and in 21 00:01:20,120 --> 00:01:22,760 Speaker 1: case you were wondering, what the heck is this news 22 00:01:22,760 --> 00:01:25,480 Speaker 1: all about? How did they pick up that gravitational wave? 23 00:01:26,120 --> 00:01:30,440 Speaker 1: What what exactly is the technology powering our sensors to 24 00:01:30,680 --> 00:01:33,360 Speaker 1: detect this stuff? How does it all work? That's what 25 00:01:33,440 --> 00:01:36,640 Speaker 1: this episode is all about. So this was the very 26 00:01:36,680 --> 00:01:39,520 Speaker 1: first time anyone had been able to measure a gravitational 27 00:01:39,560 --> 00:01:44,039 Speaker 1: wave directly. So today we're gonna talk all about what 28 00:01:44,200 --> 00:01:47,120 Speaker 1: that means and how it happened. Now, to begin with, 29 00:01:48,160 --> 00:01:51,080 Speaker 1: we need to lay some groundwork and to to really 30 00:01:51,080 --> 00:01:57,240 Speaker 1: get an understanding what gravitational waves are. So gravitational waves, ultimately, 31 00:01:57,280 --> 00:02:00,560 Speaker 1: we're one of the predictions made by a certain Albert 32 00:02:00,560 --> 00:02:05,720 Speaker 1: Einstein with this theory of general relativity. So in that theory, 33 00:02:06,000 --> 00:02:11,560 Speaker 1: Einstein presented this idea that our universe is filled with spacetime. 34 00:02:12,000 --> 00:02:15,400 Speaker 1: If you're a fan of science fiction, you have undoubtedly 35 00:02:15,480 --> 00:02:18,680 Speaker 1: come across that term star trek is all about the 36 00:02:18,720 --> 00:02:20,959 Speaker 1: space time continuum, and that you've got to be careful. 37 00:02:21,040 --> 00:02:23,720 Speaker 1: You could rip a hole in the fabric of space time. 38 00:02:24,639 --> 00:02:28,040 Speaker 1: As far as we know, that's not really that possible. Um, 39 00:02:28,080 --> 00:02:30,760 Speaker 1: I mean, black holes could sort of be that maybe, 40 00:02:30,840 --> 00:02:36,440 Speaker 1: But at any rate, spacetime itself. Is this calling it 41 00:02:36,520 --> 00:02:38,440 Speaker 1: stuff is probably the wrong way of putting it. But 42 00:02:38,880 --> 00:02:43,079 Speaker 1: it is like a fabric and mass hangs inside this fabric. 43 00:02:43,840 --> 00:02:46,960 Speaker 1: And by mass, i'm talking about stuff like stars or 44 00:02:46,960 --> 00:02:51,960 Speaker 1: even an entire solar systems or galaxies that hang in 45 00:02:52,320 --> 00:02:55,600 Speaker 1: this fabric, and just like you would see in a 46 00:02:55,680 --> 00:03:00,320 Speaker 1: two dimensional display, Uh, it ends up curving the brick 47 00:03:00,480 --> 00:03:05,320 Speaker 1: around the mass. Uh. We often talk about this in 48 00:03:05,440 --> 00:03:10,040 Speaker 1: terms of a very simple example that's easy to imagine. Uh. 49 00:03:10,240 --> 00:03:12,840 Speaker 1: You get some sort of stretchy material. Often you'll just 50 00:03:12,880 --> 00:03:15,919 Speaker 1: hear someone say, okay, get a trampoline. You've got a trampoline, 51 00:03:16,680 --> 00:03:20,800 Speaker 1: and you put a big, heavy bowling ball on the trampoline. 52 00:03:21,120 --> 00:03:24,600 Speaker 1: So that bowling ball is going to deform the trampoline surface. 53 00:03:24,760 --> 00:03:27,440 Speaker 1: It's no longer going to be straight. It's going to 54 00:03:27,520 --> 00:03:30,280 Speaker 1: end up curving around the bowling ball to some extent, 55 00:03:30,360 --> 00:03:33,440 Speaker 1: creating kind of a dimple where the bowling ball has 56 00:03:33,520 --> 00:03:37,280 Speaker 1: has created this impression inside the trampoline, and as long 57 00:03:37,280 --> 00:03:39,960 Speaker 1: as the bowling ball is there, that impression is going 58 00:03:40,000 --> 00:03:42,920 Speaker 1: to stay. This is sort of the like the way 59 00:03:43,000 --> 00:03:48,760 Speaker 1: spacetime curves around giant masses like stars and black holes, 60 00:03:48,880 --> 00:03:52,040 Speaker 1: things like that. Of course, we have to remember that 61 00:03:52,120 --> 00:03:55,720 Speaker 1: spacetime is actually four dimensional, not a two dimensional thing 62 00:03:55,760 --> 00:03:58,320 Speaker 1: like a trampoline. I mean, I know that trampolines technically 63 00:03:58,360 --> 00:04:01,320 Speaker 1: have three dimensions, but we're really looking at a surface, 64 00:04:01,360 --> 00:04:04,640 Speaker 1: so it's more like a two dimensional plane. In reality, 65 00:04:04,760 --> 00:04:07,560 Speaker 1: In spacetime it's four dimensional because you've got the three 66 00:04:07,880 --> 00:04:11,960 Speaker 1: spatial dimensions plus time, and that is a little difficult 67 00:04:11,960 --> 00:04:15,080 Speaker 1: to get your head around. But that's why we tend 68 00:04:15,120 --> 00:04:17,240 Speaker 1: to look at this two dimensional example. It's a lot 69 00:04:17,320 --> 00:04:21,039 Speaker 1: easier for us to imagine. So let's go a little 70 00:04:21,040 --> 00:04:23,800 Speaker 1: further with that analogy to kind of talk about gravity. 71 00:04:23,880 --> 00:04:26,840 Speaker 1: See Einstein proposed that gravity was a manifestation of this 72 00:04:26,920 --> 00:04:30,839 Speaker 1: curved space time. And if we take that trampoline example, 73 00:04:30,960 --> 00:04:33,240 Speaker 1: Let's say that you have a regular trampoline. You haven't 74 00:04:33,240 --> 00:04:35,200 Speaker 1: put the bowling ball on there yet, so it's a 75 00:04:35,279 --> 00:04:37,720 Speaker 1: nice flat surface, and you have a marble, and you 76 00:04:37,880 --> 00:04:40,440 Speaker 1: roll the marble across the surface of the trampoline. So 77 00:04:40,480 --> 00:04:43,000 Speaker 1: if there's nothing else there, and if the trampoline is level, 78 00:04:43,080 --> 00:04:46,600 Speaker 1: if the surfaces level, the marble should just roll in 79 00:04:46,640 --> 00:04:48,760 Speaker 1: the straight line from one side of the trampoline to 80 00:04:48,800 --> 00:04:52,080 Speaker 1: the other. No problem. Now, let's say you put that big, 81 00:04:52,080 --> 00:04:54,640 Speaker 1: heavy bowling ball on the trampoline. It creates that dimple, 82 00:04:55,080 --> 00:04:57,200 Speaker 1: and then you try and roll the marble across the 83 00:04:57,240 --> 00:05:00,960 Speaker 1: trampoline surface. Well, now that dim bowl is going to 84 00:05:01,080 --> 00:05:03,560 Speaker 1: end up affecting the pathway of the marble. It's going 85 00:05:03,600 --> 00:05:08,320 Speaker 1: to start to spiral inward toward the bowling ball. Ultimately 86 00:05:08,360 --> 00:05:11,159 Speaker 1: it'll end up making contact with the bowling ball. And 87 00:05:11,440 --> 00:05:14,880 Speaker 1: Einstein said, that's essentially what gravity is. It's that you've 88 00:05:14,920 --> 00:05:20,040 Speaker 1: got these large masses that curves spacetime to the extent 89 00:05:20,160 --> 00:05:24,839 Speaker 1: that smaller masses are spiraling inward toward the large mass. 90 00:05:24,920 --> 00:05:27,600 Speaker 1: It's just happening on a scale that's much much, much 91 00:05:27,720 --> 00:05:32,599 Speaker 1: larger than any bowling ball marble example. But that this 92 00:05:32,680 --> 00:05:36,320 Speaker 1: isn't essentially what we see when we see planets orbiting 93 00:05:36,520 --> 00:05:40,239 Speaker 1: a sun, or we see a moon orbiting a planet, 94 00:05:40,440 --> 00:05:43,719 Speaker 1: or we see star systems orbiting a galaxy, you know, 95 00:05:43,839 --> 00:05:48,040 Speaker 1: the center of a galaxy. And uh, it's all because 96 00:05:48,080 --> 00:05:51,280 Speaker 1: of this curve spacetime. Now, all of that already is 97 00:05:51,320 --> 00:05:53,600 Speaker 1: pretty heavy stuff. And keep in mind, there was not 98 00:05:53,640 --> 00:05:59,159 Speaker 1: really any way to directly observe this. It was mostly 99 00:05:59,200 --> 00:06:04,320 Speaker 1: the the uh just just Einstein using logic to work 100 00:06:04,360 --> 00:06:09,320 Speaker 1: all this out and math logic and math, and ultimately 101 00:06:09,839 --> 00:06:12,599 Speaker 1: it fit with what we saw of the universe. But 102 00:06:13,120 --> 00:06:15,440 Speaker 1: we weren't able to test a lot of this. But 103 00:06:15,520 --> 00:06:19,120 Speaker 1: then it gets even more mind blowing because now we 104 00:06:19,160 --> 00:06:22,760 Speaker 1: have to get to gravitational waves. So Einstein said that 105 00:06:22,800 --> 00:06:26,359 Speaker 1: if a mass were large enough and either changed shape 106 00:06:26,920 --> 00:06:30,040 Speaker 1: rapidly enough, or it changed its movement in some way, 107 00:06:30,800 --> 00:06:34,360 Speaker 1: uh really really quickly, it would cause ripples of space 108 00:06:34,360 --> 00:06:38,799 Speaker 1: time to move outward from that event at the speed 109 00:06:38,839 --> 00:06:42,320 Speaker 1: of light. And those ripples are what we call gravitational waves, 110 00:06:42,560 --> 00:06:45,599 Speaker 1: which are different from gravity waves. By the way, I 111 00:06:45,680 --> 00:06:48,200 Speaker 1: have been known to accidentally say gravity waves instead of 112 00:06:48,240 --> 00:06:50,960 Speaker 1: gravitational waves. But the two are different things. A gravity 113 00:06:50,960 --> 00:06:55,760 Speaker 1: wave is a wave that exists because of gravity. In 114 00:06:55,760 --> 00:06:57,880 Speaker 1: other words, it's a physical wave of some sort of 115 00:06:57,880 --> 00:07:01,880 Speaker 1: fluid system, whether it's atmosphere or or water or some 116 00:07:01,960 --> 00:07:05,440 Speaker 1: other liquid. Uh. That's a gravity wave on a planet's surface. 117 00:07:05,600 --> 00:07:07,880 Speaker 1: It's not the same thing as a gravitational wave, which 118 00:07:07,920 --> 00:07:11,320 Speaker 1: is really a ripple of space time and like I said, 119 00:07:11,360 --> 00:07:13,200 Speaker 1: it moves outward from that event at the speed of 120 00:07:13,280 --> 00:07:17,840 Speaker 1: light um and stuff that could cause significant gravitational waves. 121 00:07:17,880 --> 00:07:20,440 Speaker 1: Things that would be big enough for us to potentially 122 00:07:20,520 --> 00:07:22,680 Speaker 1: pick up here on Earth if we had the right equipment, 123 00:07:23,200 --> 00:07:26,280 Speaker 1: would include things like two black holes orbiting or colliding 124 00:07:26,320 --> 00:07:29,240 Speaker 1: with one another, which in fact, that was the event 125 00:07:29,920 --> 00:07:34,200 Speaker 1: that we were able to pick up with the ligo facilities, 126 00:07:34,240 --> 00:07:37,440 Speaker 1: and I'll talk about those in just a bit. But 127 00:07:37,520 --> 00:07:40,160 Speaker 1: there could be other stuff too, like neutron stars orbiting 128 00:07:40,160 --> 00:07:45,080 Speaker 1: one another fast enough would generate gravitational waves, or a 129 00:07:45,080 --> 00:07:48,560 Speaker 1: supernova explosion would create one as well. And each of 130 00:07:48,560 --> 00:07:51,640 Speaker 1: these events give off a huge amount of energy, and 131 00:07:51,760 --> 00:07:54,920 Speaker 1: some of the energy gets converted into making these gravitational waves. 132 00:07:54,920 --> 00:07:58,000 Speaker 1: So one takeaway from this prediction something that Einstein said 133 00:07:58,000 --> 00:08:03,200 Speaker 1: would happen is that an event that produces gravitational waves 134 00:08:03,720 --> 00:08:06,960 Speaker 1: is an event in which energy is being lost, So 135 00:08:07,000 --> 00:08:10,680 Speaker 1: you would expect to see less energy within that system 136 00:08:10,720 --> 00:08:14,560 Speaker 1: afterward than before. Uh. And it would be a hundred 137 00:08:14,640 --> 00:08:18,680 Speaker 1: years from the time of publication of the theory of 138 00:08:18,720 --> 00:08:22,560 Speaker 1: general relativity to the time when scientists announced that they 139 00:08:22,560 --> 00:08:27,560 Speaker 1: had detected a gravitational wave directly. And that's because gravitational 140 00:08:27,560 --> 00:08:32,120 Speaker 1: waves are devilishly difficult to detect. And that's some alliteration 141 00:08:32,240 --> 00:08:36,400 Speaker 1: for you right there. So gravitational waves are invisible. They 142 00:08:36,440 --> 00:08:39,959 Speaker 1: don't emit any sort of electromagnetic radiation, so we can't 143 00:08:40,000 --> 00:08:44,199 Speaker 1: see them. We can't detect them with radio detectors, nothing 144 00:08:44,240 --> 00:08:48,200 Speaker 1: like that. Uh And that makes it pretty tricky to 145 00:08:48,200 --> 00:08:50,800 Speaker 1: figure out where they are. But they do just pass 146 00:08:50,840 --> 00:08:54,000 Speaker 1: through the universe. They don't get absorbed or scattered the 147 00:08:54,000 --> 00:08:57,720 Speaker 1: way electromagnetic radiation does. If you hold up a mirror 148 00:08:57,960 --> 00:09:00,920 Speaker 1: and light hits the mirror, light will bounce off the mirror. 149 00:09:01,040 --> 00:09:04,440 Speaker 1: That's not the case with gravitational waves. They pass right through. Uh. 150 00:09:05,280 --> 00:09:10,800 Speaker 1: So it's a very different thing than electromagnetic radiation. UM. 151 00:09:10,840 --> 00:09:15,160 Speaker 1: And while they're generated from enormous events, the gravitational waves 152 00:09:15,240 --> 00:09:17,440 Speaker 1: aren't very strong. By the time they get to Earth. 153 00:09:17,640 --> 00:09:21,720 Speaker 1: They are pretty weak, so weak that you would need 154 00:09:21,760 --> 00:09:24,400 Speaker 1: an incredibly sensitive tool in order to pick them up. 155 00:09:24,840 --> 00:09:26,800 Speaker 1: And also you have to be searching at the right time, 156 00:09:27,280 --> 00:09:31,280 Speaker 1: because if the event that generated the gravitational waves happened 157 00:09:31,360 --> 00:09:35,040 Speaker 1: a billion years ago, but the location is four billion 158 00:09:35,160 --> 00:09:38,280 Speaker 1: light years from Earth, then we would have to wait 159 00:09:38,320 --> 00:09:42,360 Speaker 1: another three billion years for those gravitational waves to get 160 00:09:42,400 --> 00:09:44,559 Speaker 1: to us, because again, they travel at the speed of light. 161 00:09:44,679 --> 00:09:47,400 Speaker 1: That's their limit, So you have to be at the 162 00:09:47,520 --> 00:09:49,320 Speaker 1: right place at the right time to pick these things 163 00:09:49,400 --> 00:09:52,880 Speaker 1: up and uh, and in some cases you might argue 164 00:09:52,880 --> 00:09:59,040 Speaker 1: that that's incredibly fortuitous. Although to be fair, it looks 165 00:09:59,080 --> 00:10:03,160 Speaker 1: like the events that could generate gravitational waves happened pretty 166 00:10:03,200 --> 00:10:06,800 Speaker 1: frequently throughout the universe. But the universe is huge, so 167 00:10:06,960 --> 00:10:10,320 Speaker 1: if they're happening far away, far enough away, it will 168 00:10:10,360 --> 00:10:12,400 Speaker 1: take a very long time for that information to get 169 00:10:12,440 --> 00:10:17,040 Speaker 1: to us. So before the announcement on February eleven, sixteen, 170 00:10:17,120 --> 00:10:21,600 Speaker 1: scientists had observed phenomena that supported the existence of gravitational waves, 171 00:10:21,679 --> 00:10:26,640 Speaker 1: but we're not direct observations of a gravitational wave. Here's 172 00:10:26,640 --> 00:10:29,720 Speaker 1: an example. A pair of astronomers in Puerto Rico in 173 00:10:29,760 --> 00:10:32,800 Speaker 1: the nineteen seventies noticed that there was a binary pulsar 174 00:10:32,840 --> 00:10:37,040 Speaker 1: system and they went back to the theory of general 175 00:10:37,080 --> 00:10:40,319 Speaker 1: relativity because this was a sort of system that would 176 00:10:40,360 --> 00:10:43,520 Speaker 1: be exactly the type to generate gravitational waves according to 177 00:10:43,600 --> 00:10:48,880 Speaker 1: the predictions from general relativity, and because general relativity predicted, hey, 178 00:10:49,040 --> 00:10:51,959 Speaker 1: if it can create gravitational waves, it's going to lose 179 00:10:52,080 --> 00:10:55,880 Speaker 1: energy over time, they ended up coming up with the 180 00:10:55,960 --> 00:11:00,000 Speaker 1: hypothesis that well, over time, this binary pulsar system should 181 00:11:00,120 --> 00:11:03,240 Speaker 1: start to slow down because it's it's losing energy. It 182 00:11:03,320 --> 00:11:07,760 Speaker 1: can't keep up at the speed it's going. So they 183 00:11:07,800 --> 00:11:10,800 Speaker 1: decided to keep an eye on it. And by keeping 184 00:11:10,800 --> 00:11:13,240 Speaker 1: an eye on it, I mean they continue to observe 185 00:11:13,360 --> 00:11:18,600 Speaker 1: this pulstar system over the course of eight years, and 186 00:11:18,640 --> 00:11:20,560 Speaker 1: by the end of the eight year period, they were 187 00:11:20,640 --> 00:11:24,440 Speaker 1: comparing the findings they were observing to the predictions made 188 00:11:24,440 --> 00:11:27,640 Speaker 1: by general relativity, and they were matching up. It was 189 00:11:27,920 --> 00:11:31,240 Speaker 1: it was unfolding exactly the way Einstein predicted it should 190 00:11:31,320 --> 00:11:35,440 Speaker 1: unfold based upon his theory of general relativity, which is 191 00:11:35,480 --> 00:11:38,400 Speaker 1: incredible when you think about it, that the observations are 192 00:11:38,400 --> 00:11:42,320 Speaker 1: matching up so neatly against the predictions. Uh, you know, 193 00:11:42,320 --> 00:11:47,360 Speaker 1: it just shows how how keenly aware Einstein was of 194 00:11:47,400 --> 00:11:50,000 Speaker 1: how our universe appears to work. Keeping in mind the 195 00:11:50,000 --> 00:11:55,600 Speaker 1: general relativity. While an amazing idea collection of ideas, really 196 00:11:57,040 --> 00:12:01,520 Speaker 1: it doesn't encompass everything we know, right, it doesn't. It 197 00:12:01,520 --> 00:12:05,439 Speaker 1: doesn't really address quantum mechanics, for example, at least not 198 00:12:05,440 --> 00:12:09,360 Speaker 1: in a way that incorporates it with classical physics. But 199 00:12:10,720 --> 00:12:13,360 Speaker 1: based upon what it did cover, it seems like it 200 00:12:13,400 --> 00:12:19,920 Speaker 1: was an incredibly accurate theory. Alright, so this was really 201 00:12:19,920 --> 00:12:24,400 Speaker 1: considered strong but indirect support of gravitational waves because again 202 00:12:24,600 --> 00:12:28,600 Speaker 1: the astronomers didn't observe gravitational waves directly. They couldn't see 203 00:12:28,640 --> 00:12:31,679 Speaker 1: them or detect them, but they could see the effects, 204 00:12:32,520 --> 00:12:35,400 Speaker 1: and again it was matching up with the predictions made 205 00:12:35,400 --> 00:12:38,959 Speaker 1: from general relativity, So it was good indirect evidence that 206 00:12:39,040 --> 00:12:42,600 Speaker 1: gravitational waves existed. Then there was an event a couple 207 00:12:42,600 --> 00:12:45,880 Speaker 1: of years ago that you might have heard about, when 208 00:12:46,640 --> 00:12:51,680 Speaker 1: a team of researchers working on the BICEP two telescope, 209 00:12:52,280 --> 00:12:56,320 Speaker 1: which is in an Antarctica, had announced that they thought 210 00:12:56,600 --> 00:13:01,480 Speaker 1: they might have discovered evidence of gravitational waves that supported 211 00:13:01,800 --> 00:13:06,800 Speaker 1: a hypothesis called cosmic inflation. That's a lot of information 212 00:13:06,920 --> 00:13:08,800 Speaker 1: right there, so let me explain what all that means. 213 00:13:10,120 --> 00:13:14,000 Speaker 1: Cosmic inflation is a hypothesis that relates to the Big 214 00:13:14,000 --> 00:13:17,280 Speaker 1: Bang theory. So with a Big Bang theory, you've got 215 00:13:17,320 --> 00:13:21,160 Speaker 1: this event in which the universe undergoes a period of 216 00:13:21,240 --> 00:13:26,520 Speaker 1: rapid expansion. Cosmic inflation is kind of that rapid expansion 217 00:13:26,679 --> 00:13:30,640 Speaker 1: on steroids. The idea being that well, when we look 218 00:13:30,679 --> 00:13:34,320 Speaker 1: at our universe and we look at the the what 219 00:13:34,440 --> 00:13:38,480 Speaker 1: we can observe, it appears that our observations don't quite 220 00:13:38,480 --> 00:13:42,520 Speaker 1: match up with what we would expect if we had 221 00:13:42,960 --> 00:13:48,720 Speaker 1: uh just steady expansion since the Big Bang. In other words, 222 00:13:49,120 --> 00:13:51,360 Speaker 1: we look at all the information we have available to us, 223 00:13:51,440 --> 00:13:54,720 Speaker 1: and it looks to us that it doesn't quite match up. 224 00:13:54,760 --> 00:13:59,280 Speaker 1: Something's got to be wrong. Well. One possible explanation is 225 00:13:59,320 --> 00:14:02,520 Speaker 1: that surely after the Big Bang, and I'm by shortly, 226 00:14:02,559 --> 00:14:06,199 Speaker 1: I mean tend to the negative thirty six power seconds 227 00:14:06,240 --> 00:14:09,400 Speaker 1: after the Big Bang. So you take a ten, you 228 00:14:09,440 --> 00:14:11,800 Speaker 1: put a decimal point behind the tin, then you move 229 00:14:11,840 --> 00:14:15,560 Speaker 1: the decimal point to the left thirty six times, then 230 00:14:15,600 --> 00:14:18,200 Speaker 1: you put seconds behind that. We're talking a fraction of 231 00:14:18,240 --> 00:14:21,840 Speaker 1: a fraction of a fraction of a second. The universe 232 00:14:21,920 --> 00:14:27,360 Speaker 1: underwent massive expansion, and it only lasted from from that 233 00:14:27,440 --> 00:14:30,320 Speaker 1: point to about ten to the negative thirty third power 234 00:14:30,440 --> 00:14:36,080 Speaker 1: or thirty second power seconds, So again an instant. It's 235 00:14:36,160 --> 00:14:41,600 Speaker 1: it's completely unimaginable, at least for myself, how short an 236 00:14:41,600 --> 00:14:44,440 Speaker 1: amount of time this was. But that's how how quickly 237 00:14:44,480 --> 00:14:50,160 Speaker 1: the universe expanded, uh significantly, and then it slowed, but 238 00:14:50,280 --> 00:14:54,280 Speaker 1: it continued to expand. Now if in fact cosmic inflation 239 00:14:54,600 --> 00:14:57,720 Speaker 1: is correct, it solves a lot of the problems we 240 00:14:57,800 --> 00:15:01,400 Speaker 1: have between the what we observe of today and what 241 00:15:01,440 --> 00:15:05,160 Speaker 1: we believe happened with the Big Bang um and reconciles 242 00:15:05,280 --> 00:15:09,800 Speaker 1: those differences. If cosmic inflation is wrong, then something else 243 00:15:10,040 --> 00:15:13,120 Speaker 1: that we believe is wrong. Right. It means that what 244 00:15:13,160 --> 00:15:17,200 Speaker 1: we observe either isn't representative of reality somehow we're not 245 00:15:17,240 --> 00:15:20,240 Speaker 1: getting a big enough picture to understand it, or that 246 00:15:20,360 --> 00:15:23,800 Speaker 1: the Big Bang theory itself is flawed in some fundamental way. 247 00:15:24,360 --> 00:15:27,280 Speaker 1: We'll be back with more about HOWLEGO works in just 248 00:15:27,320 --> 00:15:37,520 Speaker 1: a second, but first let's take a quick break. So 249 00:15:38,320 --> 00:15:40,760 Speaker 1: the BICEP two team, what they were looking for was 250 00:15:41,120 --> 00:15:44,360 Speaker 1: some evidence of gravitational waves that would have been generated 251 00:15:44,480 --> 00:15:48,120 Speaker 1: during the Big Bang. This would end up supporting the 252 00:15:48,120 --> 00:15:51,160 Speaker 1: cosmic inflation hypothesis, and the way they did this was 253 00:15:51,200 --> 00:15:55,800 Speaker 1: they were looking at the cosmic microwave background or c MB. Now, 254 00:15:55,800 --> 00:16:01,120 Speaker 1: the cosmic microwave background emerged about three thousand years after 255 00:16:01,240 --> 00:16:04,320 Speaker 1: the Big Bang. This was still a period where the 256 00:16:04,400 --> 00:16:07,680 Speaker 1: universe was so dense that light could not pass through it. 257 00:16:07,680 --> 00:16:11,360 Speaker 1: It was dark and dense, but the cosmic microwave background 258 00:16:11,360 --> 00:16:18,400 Speaker 1: formed around that time. And the hypothesis stated, well, gravitational 259 00:16:18,480 --> 00:16:23,520 Speaker 1: waves would have affected the cosmic microwave background, polarizing some 260 00:16:23,720 --> 00:16:28,280 Speaker 1: of those uh, some of those particles really particles, but 261 00:16:28,320 --> 00:16:31,920 Speaker 1: some of the energy polarizing some of the cosmic microwave 262 00:16:31,960 --> 00:16:33,960 Speaker 1: background in such a way that if you were to 263 00:16:35,160 --> 00:16:38,560 Speaker 1: observe it, you could see the effect of a gravitational 264 00:16:38,600 --> 00:16:43,720 Speaker 1: wave passing through the CMB. Uh. And then as the 265 00:16:43,760 --> 00:16:49,920 Speaker 1: universe expand expanded rather uh, that that mark would also expand. 266 00:16:49,960 --> 00:16:53,680 Speaker 1: It's kind of like imagine leaving a fingerprint on some 267 00:16:53,840 --> 00:16:57,520 Speaker 1: sort of stretchy material and then stretching that material out. 268 00:16:58,080 --> 00:17:00,760 Speaker 1: The fingerprint is still there. It's deformed, but still there. 269 00:17:01,080 --> 00:17:03,240 Speaker 1: That's what the Bicept two team was looking for, was 270 00:17:03,280 --> 00:17:07,920 Speaker 1: this pattern in the CMB that would indicate that gravitational 271 00:17:07,920 --> 00:17:10,919 Speaker 1: waves from the Big Bang had passed through, and if 272 00:17:10,960 --> 00:17:13,199 Speaker 1: they found that, that would be a huge support for 273 00:17:13,240 --> 00:17:17,320 Speaker 1: cosmic inflation. And in the spring often they announced that 274 00:17:17,359 --> 00:17:22,399 Speaker 1: they believed they had found such evidence, and they also 275 00:17:22,440 --> 00:17:24,920 Speaker 1: invited other researchers to take a look at their data 276 00:17:25,040 --> 00:17:29,040 Speaker 1: and see if it was verifiable or maybe they overlooked something. 277 00:17:30,080 --> 00:17:34,159 Speaker 1: And in the fall often another team said we're sorry, 278 00:17:34,280 --> 00:17:38,639 Speaker 1: but it looks to us like space dust might have 279 00:17:38,760 --> 00:17:43,080 Speaker 1: created a false positive that what you thought it was 280 00:17:43,160 --> 00:17:46,320 Speaker 1: the polarized CMB that you had been looking for was 281 00:17:46,400 --> 00:17:49,840 Speaker 1: actually just space dust that's not actually part of the CMB. 282 00:17:50,960 --> 00:17:55,119 Speaker 1: And uh so that ended up kind of putting the 283 00:17:55,200 --> 00:17:58,639 Speaker 1: dampener on the whole celebration of finding gravitational waves to 284 00:17:58,640 --> 00:18:02,680 Speaker 1: support cosmic inflation. But even if it was completely verified, 285 00:18:02,720 --> 00:18:06,080 Speaker 1: even if BICEP two had irrefutable evidence that they had 286 00:18:06,080 --> 00:18:11,000 Speaker 1: found the presence of gravitational waves through a uh you know, 287 00:18:11,359 --> 00:18:15,080 Speaker 1: the way it affected the CNB, even then that's not 288 00:18:15,280 --> 00:18:19,040 Speaker 1: direct detection. It's still indirect. You're looking at the way 289 00:18:19,119 --> 00:18:24,720 Speaker 1: it's affected something else. So uh, you know, again, we're 290 00:18:24,720 --> 00:18:27,159 Speaker 1: still not discovering one. And and part of that is 291 00:18:27,160 --> 00:18:30,080 Speaker 1: that BICEP two is a telescope. It's looking at through 292 00:18:30,480 --> 00:18:34,439 Speaker 1: the electromagnetic spectrum. And again, gravitational waves don't show up 293 00:18:34,480 --> 00:18:37,320 Speaker 1: that way. So no telescope would help you find a 294 00:18:37,320 --> 00:18:40,800 Speaker 1: gravitational wave directly. You might be able to find how 295 00:18:40,840 --> 00:18:45,360 Speaker 1: it affected something else, but not the wave itself. Now 296 00:18:45,359 --> 00:18:48,560 Speaker 1: that's not the case with the ligo observatories. Actually it's 297 00:18:48,600 --> 00:18:53,639 Speaker 1: technically one observatory, but it has four different facilities, two 298 00:18:53,640 --> 00:18:58,160 Speaker 1: detectors UH and to research facilities that are all part 299 00:18:58,160 --> 00:19:02,800 Speaker 1: of the LIGO Observatory. LEGO itself is an acronym and 300 00:19:02,880 --> 00:19:09,080 Speaker 1: it stands for Laser Interferometer Gravitational Wave Observatory. So it's 301 00:19:09,200 --> 00:19:11,840 Speaker 1: a pair of giant detectors built on the surface of 302 00:19:11,880 --> 00:19:15,640 Speaker 1: the Earth. One is located in Hanford, Washington, the other 303 00:19:15,720 --> 00:19:20,280 Speaker 1: is in Livingstone, Louisiana. Now they're about just a little 304 00:19:20,359 --> 00:19:23,479 Speaker 1: under two thousand miles apart, or just over three thousand 305 00:19:23,560 --> 00:19:26,880 Speaker 1: kilometers apart from each other, and that's really important. I'll 306 00:19:26,880 --> 00:19:30,239 Speaker 1: explain why in a little bit. So to understand how 307 00:19:30,240 --> 00:19:32,000 Speaker 1: they work, we also have to talk about something else 308 00:19:32,040 --> 00:19:36,639 Speaker 1: that gravitational waves do as they pass through space. They 309 00:19:36,640 --> 00:19:42,040 Speaker 1: stretch and compress space itself. So again, if you were 310 00:19:42,040 --> 00:19:43,800 Speaker 1: to if you were to take a piece of elastic, 311 00:19:44,920 --> 00:19:47,880 Speaker 1: Let's say you've got a rubber band, a nice thick 312 00:19:47,960 --> 00:19:51,560 Speaker 1: rubber band, and you cut it so that it's just 313 00:19:51,680 --> 00:19:54,720 Speaker 1: one strip. When you pull on that rubber band, it 314 00:19:54,840 --> 00:19:59,320 Speaker 1: stretches along the line where you're applying force, So it 315 00:19:59,440 --> 00:20:04,560 Speaker 1: stretches in that direction, in the perpendicular direction, ninety degrees 316 00:20:04,680 --> 00:20:08,919 Speaker 1: from where you're pulling it compresses, it gets more narrow, 317 00:20:09,720 --> 00:20:12,920 Speaker 1: and then when you let it return to its normal shape, 318 00:20:13,320 --> 00:20:16,560 Speaker 1: it gets you know, the long part ends up getting 319 00:20:16,560 --> 00:20:19,600 Speaker 1: shorter and the narrow part ends of getting wider as 320 00:20:19,600 --> 00:20:24,439 Speaker 1: a result, gravitational waves do this to reality. They do 321 00:20:24,600 --> 00:20:28,280 Speaker 1: this to actual space. They stretch and compress, and it 322 00:20:28,359 --> 00:20:32,560 Speaker 1: happens several times as the wave oscillates through. Really I 323 00:20:32,560 --> 00:20:36,479 Speaker 1: should just say as the wave passes through rather than oscillates. Uh, 324 00:20:36,600 --> 00:20:41,240 Speaker 1: the distortion oscillates, but the wave passes through. So that 325 00:20:41,280 --> 00:20:45,920 Speaker 1: means the actual distance changes between two points as the 326 00:20:46,080 --> 00:20:48,840 Speaker 1: gravitational wave passes through that area. So if we were 327 00:20:48,880 --> 00:20:53,639 Speaker 1: to magnify this effect, and I mean magnify it to 328 00:20:53,760 --> 00:20:56,800 Speaker 1: a ludicrous degree, you would be able to see it. 329 00:20:57,040 --> 00:20:59,640 Speaker 1: You would actually be able to witness this. You could 330 00:20:59,680 --> 00:21:02,679 Speaker 1: stand ten feet away from someone else and when the 331 00:21:02,680 --> 00:21:06,440 Speaker 1: gravitational wave passes through, it would make it look like 332 00:21:06,520 --> 00:21:08,920 Speaker 1: the two of you suddenly got further away and then 333 00:21:08,960 --> 00:21:11,080 Speaker 1: closer to each other, and then further away and closer 334 00:21:11,080 --> 00:21:14,040 Speaker 1: to each other, even though you haven't moved anywhere, because 335 00:21:14,440 --> 00:21:21,000 Speaker 1: the distance itself is stretching and compressing. So why don't 336 00:21:21,080 --> 00:21:23,639 Speaker 1: we see that? I mean, if the celestial events that 337 00:21:23,680 --> 00:21:26,080 Speaker 1: produce gravitational waves happen on the order of something like 338 00:21:26,119 --> 00:21:29,720 Speaker 1: every fifteen minutes. Why are we all noticing this whibbly 339 00:21:29,800 --> 00:21:35,639 Speaker 1: wobbly effect. Well, it's because the actual distortion that happens 340 00:21:35,720 --> 00:21:40,640 Speaker 1: here on Earth is much much much smaller in magnitude, 341 00:21:41,480 --> 00:21:44,919 Speaker 1: so much more, so much smaller that it's difficult to 342 00:21:44,920 --> 00:21:48,680 Speaker 1: even explain. But if you were to have a supernova 343 00:21:48,800 --> 00:21:53,560 Speaker 1: explode in the Milky Way galaxy, in our galaxy, the 344 00:21:53,600 --> 00:21:58,560 Speaker 1: gravitational waves generated by that explosion would maybe be powerful 345 00:21:58,680 --> 00:22:01,520 Speaker 1: enough to distort the distance between the Earth and the 346 00:22:01,560 --> 00:22:06,400 Speaker 1: Sun by about the diameter of a hydrogen atom, so 347 00:22:07,040 --> 00:22:12,280 Speaker 1: not noticeable to any degree, not at least to human senses. 348 00:22:12,840 --> 00:22:14,600 Speaker 1: So if you were to even go on a smaller scale, 349 00:22:14,680 --> 00:22:17,480 Speaker 1: let's say that you you pick two points that are 350 00:22:17,480 --> 00:22:20,080 Speaker 1: a kilometer apart here on the surface of the Earth, 351 00:22:21,200 --> 00:22:24,240 Speaker 1: the amount of distortion would be equivalent to a few 352 00:22:24,359 --> 00:22:28,639 Speaker 1: thousands of the diameter of a proton. So you're talking 353 00:22:28,640 --> 00:22:31,840 Speaker 1: about a sub atomic particle, and just a tiny, tiny, 354 00:22:31,880 --> 00:22:35,960 Speaker 1: tiny fraction of that sub atomic particles diameter would be 355 00:22:36,000 --> 00:22:39,440 Speaker 1: the amount of distortion that would happen across a kilometer 356 00:22:39,600 --> 00:22:43,560 Speaker 1: worth of distance here on Earth. Again, that means it's 357 00:22:43,600 --> 00:22:48,040 Speaker 1: so small that it's incredibly difficult to detect, so much 358 00:22:48,080 --> 00:22:52,000 Speaker 1: so that Einstein himself I was pretty sure we would 359 00:22:52,000 --> 00:22:55,560 Speaker 1: never be able to directly detect gravitational waves because he 360 00:22:55,560 --> 00:22:58,280 Speaker 1: could not imagine a system that would be sensitive enough 361 00:22:58,400 --> 00:23:03,480 Speaker 1: to pick up such a minute change, a distortion that's 362 00:23:03,520 --> 00:23:06,159 Speaker 1: happening so quickly because it's a fraction of a second, 363 00:23:06,800 --> 00:23:12,359 Speaker 1: and it's so small as to be unnoticeable. So the 364 00:23:12,400 --> 00:23:15,439 Speaker 1: other problem here is not just that it's such a 365 00:23:15,560 --> 00:23:17,840 Speaker 1: very tiny effect that lasts a short amount of time. 366 00:23:17,840 --> 00:23:20,520 Speaker 1: It's also that a lot of other stuff could create 367 00:23:20,560 --> 00:23:26,280 Speaker 1: false positives. You can have incredibly sensitive instrumentation, but if 368 00:23:26,720 --> 00:23:31,040 Speaker 1: that instrument is really really sensitive, any sort of interference 369 00:23:31,080 --> 00:23:35,840 Speaker 1: could set off and you could end up getting false readings. 370 00:23:35,880 --> 00:23:40,600 Speaker 1: So a change in air pressure or temperature, or seismic activity, 371 00:23:40,920 --> 00:23:46,360 Speaker 1: even a heavy truck driving nearby could set off false results. 372 00:23:46,920 --> 00:23:48,600 Speaker 1: So you have to come up with a really clever 373 00:23:48,680 --> 00:23:53,160 Speaker 1: way to measure distortion, to limit vibration, and to eliminate 374 00:23:53,200 --> 00:23:55,720 Speaker 1: the chance that it was a false positive. And Lego 375 00:23:56,160 --> 00:23:59,040 Speaker 1: is the answer to all of that. So the Lego 376 00:23:59,119 --> 00:24:03,040 Speaker 1: Observatory is actually the result of decades of collaborative work 377 00:24:03,119 --> 00:24:08,080 Speaker 1: among different scientific research centers and international bodies and universities, 378 00:24:08,960 --> 00:24:12,000 Speaker 1: and all started back in nineteen seventy nine. That's when 379 00:24:12,040 --> 00:24:15,320 Speaker 1: the National Science Foundation approved funds for cal Tech and 380 00:24:15,480 --> 00:24:18,639 Speaker 1: m i T to develop laser interferometer research and development. 381 00:24:19,640 --> 00:24:22,160 Speaker 1: And a few years later, in nineteen eighty three, Caltech 382 00:24:22,240 --> 00:24:24,560 Speaker 1: and m i T submitted a proposal for a kilometer 383 00:24:24,720 --> 00:24:29,240 Speaker 1: scale detector. Uh but keep in mind, all right, so 384 00:24:29,440 --> 00:24:31,879 Speaker 1: nineteen seventy nine you get the funding for R and 385 00:24:32,000 --> 00:24:36,200 Speaker 1: D three, there's the submission of a proposal for a 386 00:24:36,320 --> 00:24:41,640 Speaker 1: kilometer scale detector. There wouldn't be approval for a detector 387 00:24:41,800 --> 00:24:48,680 Speaker 1: until nineteen nine, so almost a decade later, and which 388 00:24:48,920 --> 00:24:52,160 Speaker 1: turns out was probably okay, because we really didn't have 389 00:24:52,320 --> 00:24:57,720 Speaker 1: the technological ability to detect things on a scale small 390 00:24:57,840 --> 00:25:01,880 Speaker 1: enough to register a gravitational wave the first place. But 391 00:25:01,880 --> 00:25:04,840 Speaker 1: but still, you know, a decade's delay before you even 392 00:25:04,880 --> 00:25:08,640 Speaker 1: get approval is still pretty rough. Construction didn't begin until 393 00:25:10,880 --> 00:25:14,640 Speaker 1: the inauguration of the Ligo Observatory took place in nineteen 394 00:25:16,359 --> 00:25:19,960 Speaker 1: but even then that didn't mean that the the observatory 395 00:25:20,040 --> 00:25:23,040 Speaker 1: was online collecting data. It didn't do that until two 396 00:25:23,040 --> 00:25:28,960 Speaker 1: thousand two, and here's the kicker. Eventually scientists came to 397 00:25:28,960 --> 00:25:33,520 Speaker 1: the conclusion that this Ligo observatory was not sensitive enough 398 00:25:33,560 --> 00:25:36,480 Speaker 1: to detect gravitational waves. That despite the fact that it 399 00:25:36,600 --> 00:25:41,919 Speaker 1: was this large UH detector or pair of large detectors, 400 00:25:41,920 --> 00:25:45,800 Speaker 1: actually because again one in Louisiana one in Washington, it 401 00:25:45,880 --> 00:25:50,520 Speaker 1: wasn't sensitive enough to be effective. So it was not 402 00:25:50,600 --> 00:25:53,359 Speaker 1: quite back to the drawing board. But it didn't mean 403 00:25:53,400 --> 00:25:57,000 Speaker 1: that they had to think about how they would upgrade 404 00:25:57,040 --> 00:26:00,200 Speaker 1: these facilities so that they could be sensitive and off 405 00:26:00,240 --> 00:26:03,359 Speaker 1: to pick up a gravitational wave. So in two Ligo 406 00:26:03,440 --> 00:26:08,960 Speaker 1: went offline to undergo a big overhaul, and it took 407 00:26:09,000 --> 00:26:12,800 Speaker 1: four years of construction and testing to get it into 408 00:26:12,840 --> 00:26:16,200 Speaker 1: shape and another year to set it up for new observations, 409 00:26:16,560 --> 00:26:19,080 Speaker 1: which means that it wasn't until twenty fifteen that it 410 00:26:19,119 --> 00:26:22,200 Speaker 1: was ready to come back online. By now it was 411 00:26:22,240 --> 00:26:26,320 Speaker 1: called the Advanced Ligo Observatory, and it began collecting data 412 00:26:26,400 --> 00:26:33,840 Speaker 1: in September. Literally days after it had come online, it 413 00:26:33,960 --> 00:26:37,879 Speaker 1: picked up a gravitational wave. So that's pretty phenomenal that 414 00:26:38,280 --> 00:26:40,960 Speaker 1: just a couple of days, just a few days really 415 00:26:41,000 --> 00:26:45,040 Speaker 1: after it had been turned on again in we got 416 00:26:45,080 --> 00:26:48,480 Speaker 1: a hit. So it was incredibly exciting. So how did 417 00:26:48,480 --> 00:26:52,040 Speaker 1: this happen? How does it actually work? Well, we have 418 00:26:52,080 --> 00:26:54,919 Speaker 1: to take a look at what interferometers are all about. 419 00:26:55,840 --> 00:27:00,360 Speaker 1: An interferometer uses a technique in which electromagnetic wave are 420 00:27:00,400 --> 00:27:04,440 Speaker 1: superimposed on one another in order to get information. Now, 421 00:27:04,520 --> 00:27:07,000 Speaker 1: Ligo does this with a laser beam because it's a 422 00:27:07,080 --> 00:27:11,440 Speaker 1: laser interferometer, and the laser beam gets shot through a 423 00:27:11,480 --> 00:27:15,479 Speaker 1: beam splitter and the beams, the two beams that result 424 00:27:15,560 --> 00:27:19,919 Speaker 1: go down too long vacuum tubes, so both of the 425 00:27:20,000 --> 00:27:23,800 Speaker 1: Lego detectors are in an l shape. So you've got 426 00:27:23,840 --> 00:27:26,919 Speaker 1: these long, long vacuum tubes that extend two and a 427 00:27:26,920 --> 00:27:30,520 Speaker 1: half miles or about four kilometers out from the crux 428 00:27:31,240 --> 00:27:37,240 Speaker 1: from the the angle where they meet up and each 429 00:27:37,280 --> 00:27:39,640 Speaker 1: one is you know, they're both the same length. They 430 00:27:39,680 --> 00:27:43,000 Speaker 1: have to be exactly the same length. And the way 431 00:27:43,040 --> 00:27:45,760 Speaker 1: this works is that, uh, kind of behind the crux, 432 00:27:45,800 --> 00:27:48,080 Speaker 1: you've got a laser that shoots out a beam of 433 00:27:48,160 --> 00:27:51,639 Speaker 1: light to a beam splitter. The splitter does exactly what 434 00:27:51,800 --> 00:27:54,160 Speaker 1: it sounds like it does. It splits the beam into 435 00:27:54,200 --> 00:28:02,000 Speaker 1: two separate beams with with alternating canceling wavelengths. I guess 436 00:28:02,000 --> 00:28:05,880 Speaker 1: I should say, so the the troughs and peaks on 437 00:28:05,880 --> 00:28:09,600 Speaker 1: one match up with the peaks and troughs of the other. 438 00:28:10,119 --> 00:28:13,400 Speaker 1: That's really important when we get a little further down 439 00:28:13,480 --> 00:28:18,840 Speaker 1: the line here. So one of those two beams goes 440 00:28:18,920 --> 00:28:23,440 Speaker 1: down one branch of this l shaped detector. The other 441 00:28:23,480 --> 00:28:25,840 Speaker 1: beam goes down the other branch. And keep in mind, 442 00:28:25,920 --> 00:28:28,560 Speaker 1: like I said, both of these branches are exactly the 443 00:28:28,640 --> 00:28:31,200 Speaker 1: same length two and a half miles or four kilometers. 444 00:28:32,040 --> 00:28:34,960 Speaker 1: When the laser gets to the end, they hit a mirror. 445 00:28:35,320 --> 00:28:38,960 Speaker 1: Each beam hits a mirror, they come back to the 446 00:28:39,040 --> 00:28:43,680 Speaker 1: point of origin. And because the two laser beams have 447 00:28:44,760 --> 00:28:49,880 Speaker 1: these uh these counteracting wave lengths, they cancel each other out. 448 00:28:51,400 --> 00:28:53,760 Speaker 1: So the peaks on one cancel out the troughs of 449 00:28:53,800 --> 00:28:57,080 Speaker 1: the other, and vice versa. That means that no light 450 00:28:57,120 --> 00:29:00,880 Speaker 1: gets emitted through the system. And it's important because there's 451 00:29:00,880 --> 00:29:03,960 Speaker 1: actually a light detector that's part of this system as well. 452 00:29:04,000 --> 00:29:07,400 Speaker 1: It's looking for any sign of laser light, because a 453 00:29:07,400 --> 00:29:11,520 Speaker 1: sign of laser light would say that something has changed somehow. 454 00:29:11,640 --> 00:29:15,680 Speaker 1: The distances between these or the distances represented by these 455 00:29:15,720 --> 00:29:18,520 Speaker 1: two vacuum tubes has changed and that would be indicative 456 00:29:18,640 --> 00:29:22,920 Speaker 1: of an event like a gravitational wave moving through. So 457 00:29:23,080 --> 00:29:29,040 Speaker 1: if any light shines through, you know something has happened. Essentially, 458 00:29:29,080 --> 00:29:31,440 Speaker 1: it says that there's a mismatch in the lengths of 459 00:29:31,440 --> 00:29:35,360 Speaker 1: the vacuum tubes themselves. So when a gravitational wave passes through, 460 00:29:36,400 --> 00:29:40,200 Speaker 1: one vacuum tube will get shorter while the other gets longer. 461 00:29:40,800 --> 00:29:44,960 Speaker 1: And that's because the two tubes are offset by ninety degrees, 462 00:29:46,080 --> 00:29:48,880 Speaker 1: so one is going to be along one side of 463 00:29:48,920 --> 00:29:51,920 Speaker 1: the wave and that will lengthen the other will be 464 00:29:51,960 --> 00:29:55,560 Speaker 1: along uh will be perpendicular to that and will shorten 465 00:29:55,760 --> 00:29:59,000 Speaker 1: as a result. And this means that the lasers will 466 00:29:59,040 --> 00:30:03,240 Speaker 1: have different distance says to travel down, So the laser 467 00:30:03,280 --> 00:30:06,320 Speaker 1: traveling the shorter distance takes less time to get back 468 00:30:06,360 --> 00:30:09,200 Speaker 1: to the crux. The laser going down the longer distance 469 00:30:09,240 --> 00:30:11,920 Speaker 1: takes more time. And even though this is only happening 470 00:30:11,920 --> 00:30:14,560 Speaker 1: within a fraction of a second, it's long enough for 471 00:30:14,640 --> 00:30:17,040 Speaker 1: us to be able to detect the difference. And it 472 00:30:17,120 --> 00:30:19,800 Speaker 1: also means that those wave lengths don't match up anymore, 473 00:30:20,160 --> 00:30:23,120 Speaker 1: they don't cancel each other out anymore, so some of 474 00:30:23,160 --> 00:30:26,560 Speaker 1: that laser light gets admitted to the light detector, which 475 00:30:26,600 --> 00:30:32,440 Speaker 1: then indicates what's going on. It knows which which one 476 00:30:32,440 --> 00:30:35,600 Speaker 1: of the branches was short versus long, and knows how 477 00:30:35,600 --> 00:30:37,959 Speaker 1: long it happened, and knows how much it oscillated back 478 00:30:38,040 --> 00:30:42,360 Speaker 1: and forth, because obviously this is continuing as these as 479 00:30:42,360 --> 00:30:45,840 Speaker 1: the gravitational wave moves through, So you collect a lot 480 00:30:45,880 --> 00:30:47,760 Speaker 1: of data in a short amount of time. And we're 481 00:30:47,760 --> 00:30:50,800 Speaker 1: talking like teeny tiny slices of a second as we're 482 00:30:50,800 --> 00:30:54,479 Speaker 1: getting all this information, which is pretty incredible. You guys, 483 00:30:54,800 --> 00:30:58,520 Speaker 1: this topic is heavy because of gravitational lads, get it. 484 00:30:59,040 --> 00:31:10,600 Speaker 1: So let's take a quick break. So once you get 485 00:31:10,600 --> 00:31:13,720 Speaker 1: all that data, you can then analyze it. Actually, more importantly, 486 00:31:14,200 --> 00:31:17,600 Speaker 1: before you analyze it, you have to verify it. Now. 487 00:31:17,640 --> 00:31:20,160 Speaker 1: This is why it's important that there are two detectors, 488 00:31:20,880 --> 00:31:23,040 Speaker 1: and it's also important that they are so far apart, 489 00:31:23,240 --> 00:31:26,840 Speaker 1: like three tho kilometers apart from each other. That's because 490 00:31:26,920 --> 00:31:29,560 Speaker 1: if you get a blip on one of them, if 491 00:31:29,600 --> 00:31:32,360 Speaker 1: it's a true gravitational wave, you should also get a 492 00:31:32,360 --> 00:31:35,920 Speaker 1: blip on the other one. And because gravitational waves move 493 00:31:36,000 --> 00:31:38,440 Speaker 1: at the speed of light, there should be a slight 494 00:31:38,520 --> 00:31:42,440 Speaker 1: difference in time when both detectors pick up on this 495 00:31:42,520 --> 00:31:48,000 Speaker 1: gravitational wave somewhere right around ten milliseconds or less. In 496 00:31:48,040 --> 00:31:50,440 Speaker 1: the case of the one that was detected back in 497 00:31:51,320 --> 00:31:54,280 Speaker 1: the fall of two thousand fifteen but not announced until 498 00:31:54,320 --> 00:31:59,520 Speaker 1: two thousand sixteen, it hit the Louisiana detector first, and 499 00:31:59,640 --> 00:32:05,080 Speaker 1: seven milliseconds later it hit the Washington detector, So that 500 00:32:05,160 --> 00:32:07,840 Speaker 1: was indicative of something like a gravitational wave as opposed 501 00:32:07,880 --> 00:32:10,840 Speaker 1: to some local event that would have caused interference and 502 00:32:10,880 --> 00:32:14,360 Speaker 1: created a false positive. If an earthquake had happened in Washington, 503 00:32:15,640 --> 00:32:19,160 Speaker 1: then the facility may have may have picked something up, 504 00:32:19,920 --> 00:32:23,000 Speaker 1: but you wouldn't expect to see it in Louisiana because 505 00:32:23,160 --> 00:32:25,880 Speaker 1: it was a localized event. Same thing is true if 506 00:32:25,880 --> 00:32:29,600 Speaker 1: something had happened in Louisiana. So by seeing it happen 507 00:32:29,680 --> 00:32:33,640 Speaker 1: at both within this ten millisecond time frame meant that 508 00:32:33,920 --> 00:32:37,240 Speaker 1: it was a very good candidate for a gravitational wave 509 00:32:37,320 --> 00:32:41,960 Speaker 1: passing through. And that's exactly what happened. Um. It was 510 00:32:42,120 --> 00:32:44,720 Speaker 1: a home run in the first ending of the game, 511 00:32:45,000 --> 00:32:47,600 Speaker 1: or even really the first ad bat of the game. 512 00:32:47,640 --> 00:32:50,320 Speaker 1: It's like your first player steps up on the first 513 00:32:50,400 --> 00:32:53,520 Speaker 1: day of baseball and knocks a home run, and that 514 00:32:53,680 --> 00:32:58,120 Speaker 1: defines the moment the season. Really, that's that's the equivalent 515 00:32:58,120 --> 00:33:00,720 Speaker 1: of what we saw here on a scientific thick basis. 516 00:33:01,960 --> 00:33:06,600 Speaker 1: So the the The other thing I want to talk 517 00:33:06,600 --> 00:33:11,240 Speaker 1: about was how LEGO tries to minimize the possibility of 518 00:33:11,280 --> 00:33:13,760 Speaker 1: detecting a false positive in the first place. So, yeah, 519 00:33:13,840 --> 00:33:16,440 Speaker 1: false positives are something that that they worry about, and 520 00:33:16,440 --> 00:33:19,240 Speaker 1: the fact that there are two detectors helps minimize that. 521 00:33:19,280 --> 00:33:21,920 Speaker 1: But even so, you want to eliminate the possibility of 522 00:33:21,920 --> 00:33:25,480 Speaker 1: a false positive so that you're not constantly sifting through 523 00:33:25,560 --> 00:33:28,920 Speaker 1: noise looking for a signal. Do you want to minimize 524 00:33:28,960 --> 00:33:33,120 Speaker 1: noise as much as possible. So Lego does this through 525 00:33:33,240 --> 00:33:39,720 Speaker 1: using combinations of active and passive UH vibration reduction systems. 526 00:33:40,880 --> 00:33:43,960 Speaker 1: One thing that they do is they remove the air 527 00:33:44,280 --> 00:33:46,560 Speaker 1: from the tubes. That is why their vacuum tubes. They 528 00:33:46,600 --> 00:33:49,800 Speaker 1: remove the air for two reasons. One, they don't want 529 00:33:49,800 --> 00:33:54,320 Speaker 1: any sound passing through the chambers. Sound could possibly interfere 530 00:33:54,480 --> 00:33:59,360 Speaker 1: with the measurements. Sound would impact the mirrors, and even 531 00:33:59,440 --> 00:34:04,040 Speaker 1: a small impact would be enough to cause a problem 532 00:34:04,160 --> 00:34:07,280 Speaker 1: when you're measuring this laser. For one thing, they're looking 533 00:34:07,320 --> 00:34:11,920 Speaker 1: at distances. When they're measuring the changes between the two branches. 534 00:34:12,160 --> 00:34:14,840 Speaker 1: You know, I mentioned that one's getting longer, one's getting smaller. 535 00:34:16,120 --> 00:34:18,799 Speaker 1: The distances they're looking at are very very tiny. We're 536 00:34:18,800 --> 00:34:23,560 Speaker 1: talking ten to the negative nineteenth power meters. So again 537 00:34:23,600 --> 00:34:26,040 Speaker 1: you take the number ten, you move a decimal place 538 00:34:26,520 --> 00:34:30,000 Speaker 1: nineteen times to the left of that, and you put 539 00:34:30,080 --> 00:34:33,560 Speaker 1: meters at the end. That's the distance that these lasers 540 00:34:33,560 --> 00:34:38,319 Speaker 1: are are measuring the distortion and distance. So it's very 541 00:34:38,400 --> 00:34:41,720 Speaker 1: very very tiny, and something as simple as sound could 542 00:34:41,800 --> 00:34:44,319 Speaker 1: change that. So you can't have any sound in these 543 00:34:44,400 --> 00:34:47,280 Speaker 1: vacuum tubes. You've got to get the air out. Also, 544 00:34:47,320 --> 00:34:51,399 Speaker 1: air can absorb and uh and and scatter laser light, 545 00:34:51,719 --> 00:34:54,799 Speaker 1: which would interfere with the experiment as well, So you've 546 00:34:54,840 --> 00:34:58,320 Speaker 1: got to get air out now dawn to the vibration 547 00:34:58,360 --> 00:35:02,239 Speaker 1: reduction systems. So the active isolation system is meant to 548 00:35:02,320 --> 00:35:06,920 Speaker 1: weed out the majority of vibration, and it's active because 549 00:35:07,080 --> 00:35:11,799 Speaker 1: it is actively working against any vibration it encounters. You've 550 00:35:11,840 --> 00:35:16,960 Speaker 1: got sensors that detect vibration, they send commands to force 551 00:35:17,040 --> 00:35:22,319 Speaker 1: actuators that move in opposition to the vibration. So it's 552 00:35:22,400 --> 00:35:25,120 Speaker 1: kind of like noise canceling headphones. If you if you 553 00:35:25,120 --> 00:35:27,120 Speaker 1: put on a pair of noise canceling headphones. What they're 554 00:35:27,120 --> 00:35:30,600 Speaker 1: supposed to do is pick up any incoming sound and 555 00:35:30,600 --> 00:35:34,520 Speaker 1: then generate sound waves that are in direct opposition of 556 00:35:34,560 --> 00:35:37,920 Speaker 1: the incoming sound, so that you get a cancelation effect. 557 00:35:38,600 --> 00:35:40,919 Speaker 1: That's the same thing that these active systems are trying 558 00:35:40,920 --> 00:35:43,480 Speaker 1: to do at Ligo, except instead of it just being sound, 559 00:35:43,520 --> 00:35:46,680 Speaker 1: it's really any vibration. Although I guess you could argue 560 00:35:46,680 --> 00:35:49,840 Speaker 1: that any vibration really is sound, so it's kind of 561 00:35:49,840 --> 00:35:54,319 Speaker 1: a moot point. But anyway, they're actively trying to counteract 562 00:35:54,760 --> 00:35:58,759 Speaker 1: that vibration. But then you've got the passive system. This 563 00:35:58,800 --> 00:36:02,520 Speaker 1: is the suspension system for the mirrors, and this is 564 00:36:02,760 --> 00:36:06,120 Speaker 1: you know, the next step. So you've eliminated a huge 565 00:36:06,239 --> 00:36:09,359 Speaker 1: percentage of the vibration at this point, but that's not 566 00:36:09,400 --> 00:36:12,040 Speaker 1: good enough. You need to eliminate as much as close 567 00:36:12,080 --> 00:36:16,680 Speaker 1: to the vibration as you possibly can. So next we 568 00:36:16,719 --> 00:36:20,960 Speaker 1: look at the suspension system of Ligos mirrors, and they 569 00:36:21,000 --> 00:36:24,760 Speaker 1: are at the base of a four pendulum system. Meaning 570 00:36:24,880 --> 00:36:28,640 Speaker 1: imagine you've got a string and it ends in a 571 00:36:28,880 --> 00:36:31,760 Speaker 1: in a pendulum. A weight a mass of some sort, 572 00:36:32,400 --> 00:36:35,160 Speaker 1: and it has to be a mass of significant size, 573 00:36:35,880 --> 00:36:41,600 Speaker 1: so that it will it'll um resist moving. It's the 574 00:36:41,680 --> 00:36:45,520 Speaker 1: law of inertia, you know. UH. An object at rest 575 00:36:45,719 --> 00:36:50,000 Speaker 1: tends to stay at rest, so it will end up 576 00:36:50,040 --> 00:36:54,080 Speaker 1: absorbing a lot of vibration and minimizing it on the 577 00:36:54,120 --> 00:36:57,840 Speaker 1: other end. So you've got that first pendulum, that's pendulum 578 00:36:57,880 --> 00:37:01,759 Speaker 1: number one. From that you suspend angelum number two. So 579 00:37:01,880 --> 00:37:05,800 Speaker 1: already you're getting fewer vibrations because pendulum number one is 580 00:37:05,840 --> 00:37:09,000 Speaker 1: picking them up. What vibrations do manage to pass through 581 00:37:09,120 --> 00:37:12,239 Speaker 1: start to get picked up by pendulum number two, and 582 00:37:12,280 --> 00:37:15,960 Speaker 1: again the law of inertia means that it will dampen 583 00:37:16,000 --> 00:37:19,080 Speaker 1: a lot of that vibration. Then you've got pendulum number three, 584 00:37:19,520 --> 00:37:21,839 Speaker 1: and then beneath that you finally have the mirror, which 585 00:37:21,920 --> 00:37:26,640 Speaker 1: is forts or about eighty eight pounds worth of mirror. UH. 586 00:37:26,680 --> 00:37:30,839 Speaker 1: And hopefully after the active impassive systems have all taken 587 00:37:30,880 --> 00:37:33,720 Speaker 1: care of the vibration, nothing else is getting to that mirror. 588 00:37:34,280 --> 00:37:36,640 Speaker 1: By the way, you can actually test this out yourself, 589 00:37:36,680 --> 00:37:40,719 Speaker 1: if you like, by uh, getting four strings that are 590 00:37:41,000 --> 00:37:44,640 Speaker 1: all equal length, and some washers, some nice heavy washers. 591 00:37:45,239 --> 00:37:48,000 Speaker 1: Tie a washer at the end of the string of 592 00:37:48,080 --> 00:37:53,120 Speaker 1: the first string. Then tie a washer um so that 593 00:37:53,600 --> 00:37:56,080 Speaker 1: one end of the string connects to washer number one. 594 00:37:56,400 --> 00:37:58,480 Speaker 1: One end of the string connects to washer number two, 595 00:37:59,160 --> 00:38:00,919 Speaker 1: and so on and so fourth. And if you hold 596 00:38:00,920 --> 00:38:04,680 Speaker 1: it up and you start shaking your hand holding the string, 597 00:38:05,080 --> 00:38:08,279 Speaker 1: you'll notice that the washer at the top moves more 598 00:38:08,360 --> 00:38:11,160 Speaker 1: than the second washer, which moves more than the third, 599 00:38:11,520 --> 00:38:13,239 Speaker 1: and by the time you get down to the fourth one, 600 00:38:13,480 --> 00:38:16,120 Speaker 1: it's not moving much at all because it's been the 601 00:38:16,200 --> 00:38:19,879 Speaker 1: vibrations have been dampened by the previous pendulums, and that's 602 00:38:19,920 --> 00:38:24,560 Speaker 1: the principle of this passive system, So that helps eliminate 603 00:38:24,600 --> 00:38:28,480 Speaker 1: a lot of that vibration. Uh, without those dampening systems 604 00:38:28,480 --> 00:38:31,319 Speaker 1: in place, the two ligo detectors would be picking up 605 00:38:31,360 --> 00:38:35,080 Speaker 1: a lot of noise, and since we're still not really 606 00:38:35,080 --> 00:38:38,920 Speaker 1: sure how often gravitational waves passed through the Earth, that 607 00:38:38,960 --> 00:38:42,160 Speaker 1: would be a problem. Now. Between two thousand and two 608 00:38:42,160 --> 00:38:44,600 Speaker 1: and two thousand and ten, with the early version of LEGO, 609 00:38:44,640 --> 00:38:48,520 Speaker 1: they didn't pick up any gravitational waves at all, which 610 00:38:48,560 --> 00:38:53,759 Speaker 1: we think is because the detectors weren't sensitive enough. We 611 00:38:53,800 --> 00:38:57,040 Speaker 1: think that's the reason, but an alternative reason could be 612 00:38:58,000 --> 00:39:01,719 Speaker 1: that gravitational waves aren't as frequent as we think they are. 613 00:39:01,960 --> 00:39:04,399 Speaker 1: That they don't pass through the Earth as frequently as 614 00:39:04,960 --> 00:39:08,959 Speaker 1: we might otherwise believe. However, the opposite could be true. 615 00:39:09,200 --> 00:39:12,680 Speaker 1: We could have way more gravitational waves passing through Earth 616 00:39:13,360 --> 00:39:17,120 Speaker 1: than we had anticipated. Some of them may be so 617 00:39:17,280 --> 00:39:20,680 Speaker 1: faint that even this advanced LIGO system cannot pick it up. 618 00:39:20,920 --> 00:39:24,480 Speaker 1: There are already plans to upgrade LIGO again, and there 619 00:39:24,480 --> 00:39:29,200 Speaker 1: are other ligo observatory systems that will that are in 620 00:39:29,280 --> 00:39:35,759 Speaker 1: development now that will also listening for gravitational waves. And 621 00:39:35,840 --> 00:39:38,239 Speaker 1: listen tends to be the way most people refer to it, 622 00:39:38,320 --> 00:39:44,320 Speaker 1: like you're listening for this universal vibration moving through the Earth. 623 00:39:45,760 --> 00:39:49,760 Speaker 1: So because it was only a few days after they 624 00:39:49,800 --> 00:39:52,799 Speaker 1: came online, a lot of people are thinking that gravitational 625 00:39:52,800 --> 00:39:57,080 Speaker 1: waves are probably fairly common. Otherwise, it was just extraordinarily 626 00:39:57,200 --> 00:40:00,320 Speaker 1: lucky that we picked it up just days or the 627 00:40:00,760 --> 00:40:04,960 Speaker 1: observatory was online again. The one that we did pick 628 00:40:05,040 --> 00:40:08,319 Speaker 1: up was one point three billion light years away, which 629 00:40:08,320 --> 00:40:11,239 Speaker 1: means that the event happened one point three billion years ago. 630 00:40:11,320 --> 00:40:14,840 Speaker 1: That event being two black holes colliding with one another 631 00:40:14,880 --> 00:40:19,960 Speaker 1: to form a solitary black hole mass in the UH. 632 00:40:20,880 --> 00:40:24,880 Speaker 1: In the process, it vaporized about three solar masses worth 633 00:40:24,920 --> 00:40:30,120 Speaker 1: of of mass I guess, which is a huge amount 634 00:40:30,160 --> 00:40:34,359 Speaker 1: to think about being converted into energy, and the gravitational 635 00:40:34,360 --> 00:40:36,880 Speaker 1: waves emanated from there at the speed of light, so 636 00:40:36,960 --> 00:40:40,600 Speaker 1: one point three billion years later, Earth, which was one 637 00:40:40,640 --> 00:40:44,680 Speaker 1: point three billion light years away, picked him up. So 638 00:40:44,719 --> 00:40:48,359 Speaker 1: in a way, it was incredibly lucky. But if this 639 00:40:48,440 --> 00:40:52,680 Speaker 1: happens more frequently than we we originally believed, we might 640 00:40:52,800 --> 00:40:56,319 Speaker 1: see that this is not an uncommon event. It's very 641 00:40:56,360 --> 00:41:00,000 Speaker 1: possible that there are things we cannot see in the universe, 642 00:41:00,000 --> 00:41:05,080 Speaker 1: ears that create gravitational waves. So in other words, it's 643 00:41:05,120 --> 00:41:08,359 Speaker 1: stuff that does not give off electromagnetic radiation at all, 644 00:41:09,000 --> 00:41:11,640 Speaker 1: but it does create gravitational waves, meaning that we now 645 00:41:11,719 --> 00:41:14,799 Speaker 1: have the capacity to detect things that otherwise would have 646 00:41:14,800 --> 00:41:18,359 Speaker 1: remained completely undetectable by us. So one of the many 647 00:41:18,440 --> 00:41:22,759 Speaker 1: reasons why this discovery is so exciting it opens up 648 00:41:23,000 --> 00:41:26,640 Speaker 1: brand new science. It creates a new discipline of science, 649 00:41:26,680 --> 00:41:31,239 Speaker 1: gravitational astronomy, which can really get going now because it's 650 00:41:31,320 --> 00:41:36,200 Speaker 1: not that different from when the telescope was invented. Before 651 00:41:36,200 --> 00:41:39,600 Speaker 1: the telescope, astronomy was pretty limited. You could map out 652 00:41:39,719 --> 00:41:43,520 Speaker 1: astrological bodies when you were way back in the day 653 00:41:43,560 --> 00:41:47,160 Speaker 1: before the science of astronomy had really gotten going. Once 654 00:41:47,200 --> 00:41:50,640 Speaker 1: you started figuring out the difference between mythology and science, 655 00:41:50,719 --> 00:41:54,840 Speaker 1: then astronomy really takes over. You could map out where 656 00:41:54,880 --> 00:41:58,000 Speaker 1: these different bodies go, You could figure out which ones 657 00:41:58,040 --> 00:42:02,200 Speaker 1: are must be planets versus stars, but you couldn't really 658 00:42:03,280 --> 00:42:06,279 Speaker 1: gather a lot more information than that. You can still 659 00:42:06,320 --> 00:42:10,080 Speaker 1: get an impressive amount of data just from observing with 660 00:42:10,120 --> 00:42:13,840 Speaker 1: the naked eye, but the telescope opened up a whole 661 00:42:13,880 --> 00:42:19,080 Speaker 1: new world of study, and this gravitational wave detector system 662 00:42:19,160 --> 00:42:22,719 Speaker 1: has opened up a similar, all new world that was 663 00:42:22,920 --> 00:42:28,120 Speaker 1: not accessible by us until this year real really late, 664 00:42:28,200 --> 00:42:33,160 Speaker 1: last year late. So we might end up discovering things 665 00:42:33,239 --> 00:42:36,480 Speaker 1: that we've never been able to observe before. Will also 666 00:42:36,800 --> 00:42:40,040 Speaker 1: likely be able to study all sorts of cool stuff, 667 00:42:40,080 --> 00:42:43,280 Speaker 1: like how fast is the universe expanding, how much dark 668 00:42:43,400 --> 00:42:46,920 Speaker 1: energy is in our universe. We might learn more about 669 00:42:46,920 --> 00:42:51,560 Speaker 1: black holes already. The gravitational wave detected by the by 670 00:42:51,800 --> 00:42:57,040 Speaker 1: ligo has given us the strongest direct evidence of black holes. Um, 671 00:42:57,640 --> 00:42:59,880 Speaker 1: I guess I should say indirect evidence because it's the 672 00:43:00,239 --> 00:43:04,840 Speaker 1: gravity waves generated by the black holes. But uh, not 673 00:43:04,960 --> 00:43:08,319 Speaker 1: that we ever doubted the existence of black holes. But 674 00:43:08,360 --> 00:43:12,839 Speaker 1: this is yet more evidence and supported them. So it's 675 00:43:12,880 --> 00:43:16,640 Speaker 1: really an exciting time. We could end up learning all 676 00:43:16,680 --> 00:43:19,560 Speaker 1: sorts of stuff, stuff that we can't even anticipate right now, 677 00:43:20,200 --> 00:43:23,120 Speaker 1: and that's why it's such a big deal. I also 678 00:43:23,160 --> 00:43:26,480 Speaker 1: think that LEGO is just an incredibly elegant way of 679 00:43:26,680 --> 00:43:30,319 Speaker 1: detecting something that otherwise is impossible for us to see 680 00:43:30,440 --> 00:43:35,439 Speaker 1: or feel or experience. And it's incredibly simple, at least 681 00:43:35,640 --> 00:43:38,879 Speaker 1: on the principle of it. The technology itself is very 682 00:43:38,880 --> 00:43:41,400 Speaker 1: complicated because it has to be so sensitive to detect 683 00:43:41,400 --> 00:43:46,240 Speaker 1: these very tiny changes in distance and time, but the 684 00:43:46,280 --> 00:43:50,879 Speaker 1: principle behind it is elegant, and I mean, you don't 685 00:43:50,880 --> 00:43:53,399 Speaker 1: get much more simple than a ninety degree angle. That's 686 00:43:53,520 --> 00:43:57,920 Speaker 1: pretty bare bones there, but a very clever way of 687 00:43:57,960 --> 00:44:01,680 Speaker 1: detecting something that I Stein believed was going to be 688 00:44:01,719 --> 00:44:07,680 Speaker 1: beyond our ability to ever experience. So now we have 689 00:44:07,760 --> 00:44:11,640 Speaker 1: a revolutionary new way to examine the universe. We have 690 00:44:11,760 --> 00:44:14,160 Speaker 1: no way of knowing what sort of stuff we might 691 00:44:14,280 --> 00:44:18,560 Speaker 1: learn as a result, which is incredibly exciting. And it's 692 00:44:18,560 --> 00:44:22,080 Speaker 1: all due to some lasers, some beam splitters, and some mirrors, 693 00:44:22,920 --> 00:44:26,080 Speaker 1: and since we're already looking at lots of different organizations 694 00:44:26,480 --> 00:44:32,640 Speaker 1: building their own ligo observatories and also increasing the capacity 695 00:44:32,719 --> 00:44:38,160 Speaker 1: or or at least the sensitivity of the current ligo system. 696 00:44:38,320 --> 00:44:41,839 Speaker 1: Who knows what we're going to see next. And that 697 00:44:41,880 --> 00:44:45,000 Speaker 1: wraps up this classic episode of tech Stuff Howlego Works. 698 00:44:45,000 --> 00:44:47,480 Speaker 1: I hope you guys enjoyed it. If you have any 699 00:44:47,520 --> 00:44:51,040 Speaker 1: suggestions for future episodes of tech Stuff, send me an email. 700 00:44:51,080 --> 00:44:54,680 Speaker 1: The address is tech stuff at how stuff works dot com. 701 00:44:54,680 --> 00:44:57,960 Speaker 1: Pop on over to our website that's tech stuff podcast 702 00:44:58,080 --> 00:45:00,880 Speaker 1: dot com. You'll find an archive of all of our shows, 703 00:45:01,160 --> 00:45:03,600 Speaker 1: including all the classic episodes all the way back to 704 00:45:03,640 --> 00:45:07,800 Speaker 1: the very beginning if you so choose, and also links 705 00:45:07,880 --> 00:45:10,279 Speaker 1: to our online store. 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