1 00:00:08,680 --> 00:00:11,880 Speaker 1: Daniel, what's your favorite thing about looking up at the stars? 2 00:00:12,280 --> 00:00:14,560 Speaker 1: You mean, other than the hot coco? Did you always 3 00:00:14,600 --> 00:00:16,560 Speaker 1: drink hot coco when you look at the stars? Do 4 00:00:16,640 --> 00:00:19,360 Speaker 1: you have like a peplold in response? There? Can you 5 00:00:19,400 --> 00:00:22,080 Speaker 1: see stars if you're not holding hot coco? I've never tried. 6 00:00:22,280 --> 00:00:24,840 Speaker 1: It might steam up your glasses. No, But I mean 7 00:00:24,880 --> 00:00:27,840 Speaker 1: like about the actual stars, not not what you're drinking 8 00:00:27,840 --> 00:00:29,639 Speaker 1: when you look at them. I don't know. I love 9 00:00:29,760 --> 00:00:33,680 Speaker 1: how big everything is up there, the stars, the galaxies, 10 00:00:33,880 --> 00:00:37,680 Speaker 1: all of us, just so overwhelmingly huge. But aren't you 11 00:00:37,720 --> 00:00:39,879 Speaker 1: a little bit biased about that? What do you mean? 12 00:00:39,920 --> 00:00:41,440 Speaker 1: I mean you're only seeing the big stuff when you 13 00:00:41,440 --> 00:00:44,159 Speaker 1: look up at the sky. There's plenty of little cute 14 00:00:44,240 --> 00:00:47,200 Speaker 1: stuff on those stars or on those planets. Oh yeah, 15 00:00:47,240 --> 00:00:49,520 Speaker 1: that's true, I suppose, But it doesn't change my mind. 16 00:00:49,680 --> 00:00:52,240 Speaker 1: You still like big stuff. I like my universe the 17 00:00:52,280 --> 00:01:11,080 Speaker 1: way I like my hot coco. Big and dark him 18 00:01:11,240 --> 00:01:14,039 Speaker 1: or handy cartoonists and the creator of PhD comics. Hi, 19 00:01:14,200 --> 00:01:17,200 Speaker 1: I'm Daniel. I'm a particle businessist and a professor at 20 00:01:17,360 --> 00:01:20,839 Speaker 1: uc Herbhine, and I don't really drink that much hot coco. 21 00:01:21,080 --> 00:01:22,840 Speaker 1: But does that mean you don't look at the stars 22 00:01:22,920 --> 00:01:25,200 Speaker 1: very much. It does, unfortunately mean I don't look at 23 00:01:25,240 --> 00:01:27,160 Speaker 1: the stars very much. Basically, it's because I don't do 24 00:01:27,200 --> 00:01:29,560 Speaker 1: as much camping as I used to, and camping was 25 00:01:29,600 --> 00:01:32,000 Speaker 1: my number one way to see the stars and also 26 00:01:32,160 --> 00:01:34,160 Speaker 1: to drink hot cocoa. You know you can do all 27 00:01:34,160 --> 00:01:38,080 Speaker 1: those three things independently. What that's not true. You can't 28 00:01:38,120 --> 00:01:40,600 Speaker 1: just make hot coco at home in your living room 29 00:01:41,520 --> 00:01:43,480 Speaker 1: or look at the stars. Next, you're telling me you 30 00:01:43,480 --> 00:01:46,440 Speaker 1: can like make s'mores over your range. You could even 31 00:01:46,440 --> 00:01:49,560 Speaker 1: do it on the microwave. What you have under those 32 00:01:49,640 --> 00:01:53,400 Speaker 1: super smart microwaves? Did you got for free? I think 33 00:01:53,400 --> 00:01:55,680 Speaker 1: that would cause offense to the fundamental nature of space 34 00:01:55,680 --> 00:01:58,640 Speaker 1: and time making smores in the microwave. Yes, you'd be 35 00:01:58,760 --> 00:02:02,560 Speaker 1: blacklisted by the Boy and Girls Couts. But anyways, Welcome 36 00:02:02,600 --> 00:02:05,080 Speaker 1: to our podcast Daniel and Jorge Explain the Universe, a 37 00:02:05,160 --> 00:02:08,520 Speaker 1: production of iHeartRadio in which we take a long, deep 38 00:02:08,600 --> 00:02:12,760 Speaker 1: sip of this sweet, sweet universe, trying to appreciate all 39 00:02:12,760 --> 00:02:17,160 Speaker 1: of its incredible flavors and colors and mysteries. We look 40 00:02:17,200 --> 00:02:20,160 Speaker 1: out into the cosmos and we wonder why things are 41 00:02:20,280 --> 00:02:22,720 Speaker 1: the way they are, why they look the way they do. 42 00:02:22,840 --> 00:02:25,640 Speaker 1: And if it's possible to explain all of it, to 43 00:02:25,800 --> 00:02:28,760 Speaker 1: understand the swirling and the dancing and the frothing and 44 00:02:28,800 --> 00:02:31,639 Speaker 1: all the twoing and frowing that's happening up there in 45 00:02:31,680 --> 00:02:34,760 Speaker 1: the night sky, and to explain all of it to you, 46 00:02:35,040 --> 00:02:38,240 Speaker 1: that's right. We'd give you some more of this amazing universe, 47 00:02:38,320 --> 00:02:41,080 Speaker 1: all the hot stuff, all the cold stuff, all of 48 00:02:41,080 --> 00:02:43,560 Speaker 1: the chocolate stuff, and even all of the vanilla stuff. 49 00:02:43,560 --> 00:02:46,440 Speaker 1: That's also pretty interesting. Did you say even all of 50 00:02:46,440 --> 00:02:49,040 Speaker 1: the vanilla stuff, Like vanilla is an afterthought? I thought 51 00:02:49,040 --> 00:02:51,600 Speaker 1: you were a great defender of vanilla as an actual flavor. 52 00:02:51,760 --> 00:02:54,079 Speaker 1: I am a big defender. It's my favorite flavor. That's 53 00:02:54,120 --> 00:02:56,360 Speaker 1: like saying your favorite color is white, dude, it is. 54 00:02:56,400 --> 00:03:01,680 Speaker 1: Actually I love nothing more than a black page. The 55 00:03:01,760 --> 00:03:03,880 Speaker 1: more white I can put into my drawings, the less 56 00:03:03,880 --> 00:03:06,400 Speaker 1: work I have to do. A white page is usually 57 00:03:06,440 --> 00:03:08,680 Speaker 1: the enemy of creative types. But I'm glad that it 58 00:03:08,720 --> 00:03:11,160 Speaker 1: inspires you. But it's true that there's a lot of 59 00:03:11,160 --> 00:03:13,880 Speaker 1: stuff out there to enjoy and to experience, of all 60 00:03:13,919 --> 00:03:18,120 Speaker 1: different flavors and all different sizes. Sometimes people focus on 61 00:03:18,160 --> 00:03:21,560 Speaker 1: the biggest, craziest, most extreme stuff in the universe, but 62 00:03:21,639 --> 00:03:24,600 Speaker 1: there's a whole scale of things happening out there, tiny 63 00:03:24,639 --> 00:03:28,600 Speaker 1: little gas clouds all the way up to supermassive galaxies. 64 00:03:28,960 --> 00:03:30,880 Speaker 1: That's right, All of the big stuff in the universe 65 00:03:30,960 --> 00:03:34,040 Speaker 1: usually gets all the big headlines. People mostly pay attention 66 00:03:34,080 --> 00:03:38,200 Speaker 1: to supermassive black holes or giant superstars that are millions 67 00:03:38,240 --> 00:03:40,280 Speaker 1: of times bigger than our sun. But sometimes it's the 68 00:03:40,320 --> 00:03:42,720 Speaker 1: little stuff that can tell you a lot about the 69 00:03:43,000 --> 00:03:46,160 Speaker 1: big ideas in the universe. Because remember that we don't 70 00:03:46,200 --> 00:03:48,680 Speaker 1: get to control what happens in the universe. If we 71 00:03:48,720 --> 00:03:51,240 Speaker 1: want to learn the way the universe works, we just 72 00:03:51,320 --> 00:03:54,320 Speaker 1: got to sit back and watch the experiments that nature 73 00:03:54,400 --> 00:03:56,920 Speaker 1: has arranged for us. We don't get to say what 74 00:03:57,040 --> 00:03:59,440 Speaker 1: happens if you shoot two black holes together. We just 75 00:03:59,480 --> 00:04:02,560 Speaker 1: have to look to see if somebody has already smashed 76 00:04:02,560 --> 00:04:05,480 Speaker 1: them together. And so, because we are beggars, we don't 77 00:04:05,480 --> 00:04:07,480 Speaker 1: get to be choosers, and that means that we need 78 00:04:07,520 --> 00:04:10,280 Speaker 1: to make the most of everything that's out there. We 79 00:04:10,320 --> 00:04:11,960 Speaker 1: need to think about what we can learn from the 80 00:04:12,040 --> 00:04:14,520 Speaker 1: big stuff and also what we can learn from the 81 00:04:14,640 --> 00:04:17,400 Speaker 1: little stuff, because everything out there in the universe has 82 00:04:17,440 --> 00:04:19,640 Speaker 1: something to teach us, and there is a lot to 83 00:04:19,680 --> 00:04:22,240 Speaker 1: be taught out there in the universe, a lot of 84 00:04:22,279 --> 00:04:25,560 Speaker 1: amazing things big and small, and so today we're going 85 00:04:25,640 --> 00:04:27,720 Speaker 1: to focus on one type of thing out there in 86 00:04:27,760 --> 00:04:30,240 Speaker 1: the universe then maybe doesn't get as much attention as 87 00:04:30,440 --> 00:04:32,920 Speaker 1: some of the big stuff, so to be on the program, 88 00:04:32,920 --> 00:04:42,200 Speaker 1: we'll be asking the question what are dwarf galaxies? I 89 00:04:42,360 --> 00:04:44,040 Speaker 1: love they We're going to get to talk about dwarf 90 00:04:44,080 --> 00:04:46,840 Speaker 1: galaxies today because they are some of the most fascinating 91 00:04:46,920 --> 00:04:51,000 Speaker 1: and interesting and reviewing aspects of the universe. They have 92 00:04:51,120 --> 00:04:54,080 Speaker 1: so much to teach us about what's going on and 93 00:04:54,120 --> 00:04:57,600 Speaker 1: where everything came from. Yeah, they're pretty exciting and pretty awesome, 94 00:04:58,120 --> 00:05:00,560 Speaker 1: and so as usual, we were wondering how many people 95 00:05:00,560 --> 00:05:03,240 Speaker 1: out there had thought about dwarf galaxies or know what 96 00:05:03,320 --> 00:05:05,760 Speaker 1: they are. So thank you very much to everybody who 97 00:05:05,800 --> 00:05:09,400 Speaker 1: answers these questions for the podcast. We love hearing your thoughts, 98 00:05:09,440 --> 00:05:12,279 Speaker 1: as does everybody else. And if you are out there 99 00:05:12,320 --> 00:05:14,320 Speaker 1: and have been listening to podcast for a while and 100 00:05:14,320 --> 00:05:17,159 Speaker 1: would like to share your voice for everybody else, please 101 00:05:17,200 --> 00:05:19,720 Speaker 1: don't be shy right to us two questions at daniel 102 00:05:19,720 --> 00:05:22,120 Speaker 1: an Horgay dot com. So think about it for a second. 103 00:05:22,240 --> 00:05:26,080 Speaker 1: What do you think our dwarf galaxies. Here's what people 104 00:05:26,120 --> 00:05:28,760 Speaker 1: had to say. My guess is they're just smaller galaxies, 105 00:05:28,800 --> 00:05:32,760 Speaker 1: smaller collections of stars that have not yet been swallowed 106 00:05:32,839 --> 00:05:35,920 Speaker 1: up by a big galaxy. I would imagine at all 107 00:05:35,960 --> 00:05:39,279 Speaker 1: galaxies kind of start out that way and grow and 108 00:05:39,400 --> 00:05:43,760 Speaker 1: merge and until they become big, beautiful spirals like the 109 00:05:43,800 --> 00:05:47,800 Speaker 1: Milky Way. Dwarf galaxies are like those little mini galaxies, 110 00:05:47,800 --> 00:05:51,760 Speaker 1: and they can be like satellite galaxies to galaxies like 111 00:05:51,800 --> 00:05:55,400 Speaker 1: the Milky Way, just a tiny little galaxies, not that big. 112 00:05:55,600 --> 00:05:58,920 Speaker 1: I don't know. Maybe a dwarf galaxy is a galaxy 113 00:05:59,000 --> 00:06:02,320 Speaker 1: with not enough mass to be considered a galaxy, like 114 00:06:02,880 --> 00:06:06,320 Speaker 1: what happened to Pluto. I don't know. I'm guessing land 115 00:06:06,520 --> 00:06:11,280 Speaker 1: or galaxies, as the name suggests, are smaller galaxies. I 116 00:06:11,320 --> 00:06:14,920 Speaker 1: guess that by the name, dwarf galaxies have a lot 117 00:06:15,000 --> 00:06:19,440 Speaker 1: less stars and planets and other stuff. But I don't 118 00:06:19,480 --> 00:06:22,400 Speaker 1: know how smaller it has to be to be considered 119 00:06:22,520 --> 00:06:27,600 Speaker 1: a dwarf galaxy. The term dwarf galaxies kind of reminds 120 00:06:27,640 --> 00:06:33,000 Speaker 1: me of the galaxies that are like globular clusters, so 121 00:06:34,080 --> 00:06:36,280 Speaker 1: or it might just be as it says in the name. 122 00:06:36,360 --> 00:06:43,719 Speaker 1: They're just smaller galaxies, maybe much less stars, maybe a 123 00:06:43,720 --> 00:06:49,920 Speaker 1: different shape, maybe maybe less dark matter keeping them together. 124 00:06:52,480 --> 00:06:56,160 Speaker 1: I don't believe there probably won't be any black hole 125 00:06:56,200 --> 00:06:59,040 Speaker 1: in the center, but there might be, I don't know. 126 00:06:59,279 --> 00:07:03,680 Speaker 1: All right, straightforward answers here, everyone said they're just a galaxies, 127 00:07:03,720 --> 00:07:06,880 Speaker 1: but smaller. It's like a dwarf serving of ice cream 128 00:07:07,000 --> 00:07:10,000 Speaker 1: or a dwarf cup of cocoa. Oh yeah, that is 129 00:07:10,000 --> 00:07:13,520 Speaker 1: that a new diet perhaps little servings of everything. I 130 00:07:13,560 --> 00:07:15,800 Speaker 1: think that's maybe the oldest diet. Well that's a thing 131 00:07:15,800 --> 00:07:17,640 Speaker 1: on the internet, right, there are all these videos of 132 00:07:17,760 --> 00:07:22,800 Speaker 1: people making like little, tiny, like lego sized foods. Really 133 00:07:22,840 --> 00:07:24,400 Speaker 1: like instead of having a saying which you just have 134 00:07:24,440 --> 00:07:27,200 Speaker 1: like a tiny little sandwich. Yeah, there's this whole genre 135 00:07:27,240 --> 00:07:29,680 Speaker 1: of YouTube videos they make like tiny food. Oh but 136 00:07:29,760 --> 00:07:33,040 Speaker 1: that's not for eating, right, that's just for like being silly. 137 00:07:33,560 --> 00:07:36,240 Speaker 1: Nobody's sitting down to tuck into like a tiny roast chicken, 138 00:07:36,280 --> 00:07:38,680 Speaker 1: are they. Well maybe they could, they could, I don't know. 139 00:07:39,520 --> 00:07:41,640 Speaker 1: They usually cut the videos after they make the food. 140 00:07:41,840 --> 00:07:44,520 Speaker 1: I do like those tiny kitchen videos. Those are really fun. 141 00:07:44,800 --> 00:07:47,360 Speaker 1: All right, Well, let's dig into it, Daniel, what is 142 00:07:47,360 --> 00:07:51,080 Speaker 1: a dwarf galaxy. So everybody was basically right, Dwarf galaxies 143 00:07:51,120 --> 00:07:54,160 Speaker 1: are a little cute galaxies. Because it turns out that 144 00:07:54,320 --> 00:07:58,160 Speaker 1: galaxies come in all sorts of sizes. We tend to 145 00:07:58,200 --> 00:08:01,400 Speaker 1: think about galaxies in term of ones like our own 146 00:08:01,520 --> 00:08:05,640 Speaker 1: the Milky Way that has hundreds of billions of stars, 147 00:08:06,080 --> 00:08:08,720 Speaker 1: Like galaxies that are much much bigger than the Milky Way, 148 00:08:08,800 --> 00:08:11,600 Speaker 1: all the way down to galaxies that are very very 149 00:08:11,640 --> 00:08:15,080 Speaker 1: small things that you probably wouldn't even call a galaxy. 150 00:08:15,280 --> 00:08:17,720 Speaker 1: Maybe let's put things into perspective, but like, how big 151 00:08:17,840 --> 00:08:21,400 Speaker 1: is our galaxy? What are the size ranges that qualify 152 00:08:21,440 --> 00:08:24,160 Speaker 1: a galaxy is a dwarf galaxy? So our galaxy has 153 00:08:24,320 --> 00:08:29,160 Speaker 1: somewhere around two hundred to four hundred billion stars. That's 154 00:08:29,160 --> 00:08:31,840 Speaker 1: a really difficult number to wrap your mind around. Two 155 00:08:31,960 --> 00:08:35,200 Speaker 1: hundred like a billion times two hundred exactly. There are 156 00:08:35,240 --> 00:08:39,320 Speaker 1: more stars in the galaxy than people on Earth. Right, 157 00:08:39,440 --> 00:08:42,440 Speaker 1: It's incredible, like every single person on Earth could have 158 00:08:42,480 --> 00:08:46,040 Speaker 1: like pointier soul stars just for themselves in the Milky Way. 159 00:08:46,480 --> 00:08:49,640 Speaker 1: It's really an incredible number of stars out there, hold 160 00:08:49,679 --> 00:08:52,440 Speaker 1: them firing and burning with planets around them. Lots of 161 00:08:52,480 --> 00:08:55,000 Speaker 1: Earth like planets. It's really hard to sort of like 162 00:08:55,280 --> 00:08:57,839 Speaker 1: get the whole scope of the galaxy in your mind. 163 00:08:57,960 --> 00:09:01,080 Speaker 1: But that's the size of our galaxy, a few hundred 164 00:09:01,280 --> 00:09:04,120 Speaker 1: billion stars. You'd be like Oprah. You'd be giving up 165 00:09:04,160 --> 00:09:06,400 Speaker 1: stars to everyone. You get a star, and you get 166 00:09:06,400 --> 00:09:09,840 Speaker 1: a star, You're all stars. That's right. Donate to the 167 00:09:09,880 --> 00:09:12,959 Speaker 1: podcast and I will give you a star in return. Now, 168 00:09:13,000 --> 00:09:15,840 Speaker 1: do you offer free home delivery for that? Or do 169 00:09:15,880 --> 00:09:17,440 Speaker 1: you have to pay for shipping? See that's how they 170 00:09:17,480 --> 00:09:20,839 Speaker 1: get you the shipping. It's the free star, but it's 171 00:09:20,880 --> 00:09:23,640 Speaker 1: gonna cost you ten trillion dollars to deliver it to 172 00:09:23,679 --> 00:09:26,360 Speaker 1: your house and also the life of very human on Earth. 173 00:09:26,440 --> 00:09:28,560 Speaker 1: M Yeah, And in this case, it's not just the shipping, 174 00:09:28,720 --> 00:09:31,839 Speaker 1: it's the handling, right, because that's particularly tricky when you're 175 00:09:31,840 --> 00:09:35,040 Speaker 1: dealing with something several thousand degrees kelvin. But no, I 176 00:09:35,040 --> 00:09:37,320 Speaker 1: will email you a plaque of ownership of your star 177 00:09:37,400 --> 00:09:39,720 Speaker 1: if you donate to the podcast. Oh boy, I feel 178 00:09:39,760 --> 00:09:42,640 Speaker 1: like you just made a serious offer. Let's see if 179 00:09:42,640 --> 00:09:45,760 Speaker 1: we get any takers. But our galaxy, as big as 180 00:09:45,800 --> 00:09:48,520 Speaker 1: it is, is not even the biggest galaxy out there. 181 00:09:49,240 --> 00:09:53,000 Speaker 1: How big do galaxies get like Andromeda. How big is Andromeda? 182 00:09:53,080 --> 00:09:56,240 Speaker 1: Andromeda has more than a trillion stars in it. It's 183 00:09:56,280 --> 00:09:59,280 Speaker 1: about five times as big as the Milky Way, like 184 00:09:59,400 --> 00:10:03,400 Speaker 1: totally dwarfs us in terms of galaxies, And there are 185 00:10:03,400 --> 00:10:06,520 Speaker 1: other galaxies out there that are even bigger. WHOA, what's 186 00:10:06,559 --> 00:10:08,960 Speaker 1: the biggest galaxy that we know of? Or what's the 187 00:10:08,960 --> 00:10:12,120 Speaker 1: biggest galaxy that Google knows of? So the biggest galaxy 188 00:10:12,200 --> 00:10:14,800 Speaker 1: that we know of is about a billion light years away. 189 00:10:14,880 --> 00:10:18,880 Speaker 1: It's called I See one one oh one, and there's 190 00:10:18,880 --> 00:10:21,480 Speaker 1: a lot of uncertainty, but the current estimate is that 191 00:10:21,520 --> 00:10:24,960 Speaker 1: it has the mass of about one hundred trillion stars, 192 00:10:25,320 --> 00:10:29,400 Speaker 1: so like a hundred times more stars than Andromeda. Whoa, 193 00:10:29,600 --> 00:10:31,960 Speaker 1: which is already five times bigger than us, So it's 194 00:10:31,960 --> 00:10:35,440 Speaker 1: like five hundred times bigger than us in terms of mass. Yeah, 195 00:10:35,440 --> 00:10:38,040 Speaker 1: there's some nuances there because there's a big variation in 196 00:10:38,080 --> 00:10:41,800 Speaker 1: the masses of stars. Actually, more stars are smaller than 197 00:10:41,840 --> 00:10:44,760 Speaker 1: the mass of our sun. Remember, the most common kind 198 00:10:44,760 --> 00:10:46,800 Speaker 1: of star out there is a red dwarf, which is 199 00:10:46,840 --> 00:10:49,280 Speaker 1: smaller than the kind of star that we have. So 200 00:10:49,320 --> 00:10:51,520 Speaker 1: if you're just measuring the mass in terms of like 201 00:10:51,800 --> 00:10:55,360 Speaker 1: our solar masses, that's going to underestimate the number of 202 00:10:55,440 --> 00:10:57,920 Speaker 1: stars that are out there in that galaxy, so it 203 00:10:57,920 --> 00:11:00,560 Speaker 1: may even be more. This is just like a really 204 00:11:00,559 --> 00:11:04,239 Speaker 1: shocking number, hundreds of trillions of stars. You know. For comparison, 205 00:11:04,559 --> 00:11:07,920 Speaker 1: there's like a few trillion trees on Earth, So that 206 00:11:07,960 --> 00:11:10,720 Speaker 1: means that like every tree on Earth could have like 207 00:11:10,840 --> 00:11:14,439 Speaker 1: twenty stars in that mega galaxy. WHOA, Well, I'm not 208 00:11:14,559 --> 00:11:19,280 Speaker 1: sure trees are collecting stars these days, but you're welcome 209 00:11:19,320 --> 00:11:23,000 Speaker 1: to assign a star for every tree in the galaxy. 210 00:11:23,040 --> 00:11:25,360 Speaker 1: Any tree that donates to the podcast, I will email 211 00:11:25,400 --> 00:11:28,679 Speaker 1: them a certificate of ownership. They technic they kind of 212 00:11:28,720 --> 00:11:32,120 Speaker 1: do already because I print out the outline every single 213 00:11:32,160 --> 00:11:35,400 Speaker 1: time on paper. Wow, which means you're sacrificing trees for 214 00:11:35,400 --> 00:11:38,319 Speaker 1: the podcast. Yeah. I like to think they donated for 215 00:11:38,440 --> 00:11:42,080 Speaker 1: the good of the of knowledge, But I guess maybe 216 00:11:42,120 --> 00:11:44,000 Speaker 1: a question is like, is there an upper limit to 217 00:11:44,040 --> 00:11:46,680 Speaker 1: the size of a galaxy or can galaxies just be 218 00:11:47,040 --> 00:11:50,280 Speaker 1: infinitely big? And if there's a limit, what causes that limit? 219 00:11:50,480 --> 00:11:52,640 Speaker 1: Is it something about the conditions at the beginning of 220 00:11:52,679 --> 00:11:55,160 Speaker 1: the universe. There's no technical limit to the size of 221 00:11:55,160 --> 00:11:58,920 Speaker 1: a galaxy. Galaxies just form and get bigger and bigger. 222 00:11:59,240 --> 00:12:02,280 Speaker 1: That's fundamental the history of the universe is that galaxy 223 00:12:02,400 --> 00:12:05,920 Speaker 1: started out basically a small clumps of stars, which then 224 00:12:06,040 --> 00:12:08,800 Speaker 1: merge with other clumps of stars, and so you get 225 00:12:08,840 --> 00:12:13,360 Speaker 1: this like hierarchical formation, this merging of mergers of mergers, 226 00:12:13,480 --> 00:12:16,000 Speaker 1: and so there's no reason why you can't just like 227 00:12:16,280 --> 00:12:18,760 Speaker 1: keep clumping galaxies together, and they are going to keep 228 00:12:18,800 --> 00:12:21,920 Speaker 1: clumping together. Really, the only thing that limits the size 229 00:12:21,920 --> 00:12:24,800 Speaker 1: of the galaxy is the fact that the universe is expanding, 230 00:12:24,880 --> 00:12:28,840 Speaker 1: and that expansion is accelerating, so it's increasing the distances 231 00:12:28,880 --> 00:12:31,880 Speaker 1: between galaxies, so it sort of like keeps the galaxy 232 00:12:32,000 --> 00:12:35,320 Speaker 1: separated a little bit and prevents them from colliding all 233 00:12:35,400 --> 00:12:38,720 Speaker 1: into one huge mega galaxy. So it's a bit of 234 00:12:38,720 --> 00:12:42,959 Speaker 1: a race against time, right because recently the universes started 235 00:12:43,120 --> 00:12:46,120 Speaker 1: accelerating right in terms of its expansion, So maybe we 236 00:12:46,240 --> 00:12:48,760 Speaker 1: have seen the biggest galaxies that will ever form. Some 237 00:12:48,800 --> 00:12:51,320 Speaker 1: cosmologists think that we live at the time of the 238 00:12:51,360 --> 00:12:55,800 Speaker 1: biggest structures in the universe because of the accelerating expansion 239 00:12:55,800 --> 00:12:59,200 Speaker 1: of the universe, then size of structures cannot grow anymore 240 00:12:59,360 --> 00:13:02,920 Speaker 1: because so much space is being created between existing galaxies, 241 00:13:03,240 --> 00:13:05,880 Speaker 1: and so like we have galaxies, and we have clusters 242 00:13:05,880 --> 00:13:08,560 Speaker 1: of galaxies that are mostly held together by gravity. Then 243 00:13:08,600 --> 00:13:10,960 Speaker 1: we have superclusters which are sort of on the edge 244 00:13:10,960 --> 00:13:14,040 Speaker 1: of whether gravity can hold them together or dark energy 245 00:13:14,120 --> 00:13:16,400 Speaker 1: will rip them apart. And so it might be that 246 00:13:16,520 --> 00:13:20,680 Speaker 1: like our cluster of galaxies eventually collapses into one big galaxy, 247 00:13:21,120 --> 00:13:25,600 Speaker 1: maybe even our supercluster collapses into a super galaxy. But 248 00:13:25,760 --> 00:13:29,079 Speaker 1: the stuff and other superclusters, probably dark energy will keep 249 00:13:29,160 --> 00:13:31,640 Speaker 1: us from ever merging with them. So we might get 250 00:13:31,720 --> 00:13:34,840 Speaker 1: future bigger galaxies, but we won't ever get like bigger 251 00:13:34,840 --> 00:13:37,560 Speaker 1: blobs of stuff. We might have reached sort of like 252 00:13:37,760 --> 00:13:42,680 Speaker 1: peak size of blob or like at the end of purity, 253 00:13:43,480 --> 00:13:47,200 Speaker 1: it's all downhill after that, stuff just starts falling apart 254 00:13:47,240 --> 00:13:50,400 Speaker 1: after that. Yeah, hopefully let's get to party as much 255 00:13:50,400 --> 00:13:52,040 Speaker 1: as we can right now. But I guess it also 256 00:13:52,040 --> 00:13:54,160 Speaker 1: depends on what dark energy is going to do in 257 00:13:54,160 --> 00:13:56,679 Speaker 1: the future, right Isn't it a possibility that dark energy 258 00:13:56,720 --> 00:13:59,920 Speaker 1: will reverse and it will cause everything to start contract 259 00:14:00,200 --> 00:14:02,920 Speaker 1: and then we'll very basically at the entire universe is 260 00:14:02,920 --> 00:14:06,160 Speaker 1: going to collapse into a clump and then it'll be 261 00:14:06,200 --> 00:14:09,319 Speaker 1: like one giant galaxy. Basically, it certainly does depend on that. 262 00:14:09,480 --> 00:14:13,319 Speaker 1: The scenario we just outlined assumes that dark energy continues 263 00:14:13,440 --> 00:14:16,840 Speaker 1: the way that it has that's constant in space, and 264 00:14:16,880 --> 00:14:20,080 Speaker 1: that as space gets bigger, you add more dark energy. 265 00:14:20,160 --> 00:14:23,600 Speaker 1: So dark energy is an increasing fraction of the energy 266 00:14:23,640 --> 00:14:27,239 Speaker 1: density of the universe, which just further accelerates the expansion. 267 00:14:27,440 --> 00:14:30,280 Speaker 1: If you just extrapolate that out naively, then yeah, you 268 00:14:30,320 --> 00:14:32,760 Speaker 1: get the scenario we just outlined. But as you say, 269 00:14:32,800 --> 00:14:35,400 Speaker 1: we don't really understand dark energy where it comes from. 270 00:14:35,680 --> 00:14:38,400 Speaker 1: What is this source of potential energy that's accelerating the 271 00:14:38,440 --> 00:14:40,960 Speaker 1: expansion of the universe. Could it change? And in fact 272 00:14:41,080 --> 00:14:44,400 Speaker 1: it might, right because we don't know the underlying mechanism 273 00:14:44,640 --> 00:14:47,520 Speaker 1: that creates it. It could be that there's some complicated 274 00:14:47,560 --> 00:14:50,320 Speaker 1: dynamics there that change with time and give us a 275 00:14:50,320 --> 00:14:53,080 Speaker 1: different future. Like it could just all turn off suddenly 276 00:14:53,400 --> 00:14:56,000 Speaker 1: and then we have a big crunch where everything collapses down, 277 00:14:56,040 --> 00:15:01,760 Speaker 1: as you say, into one big superstructure, one megaga. But 278 00:15:01,880 --> 00:15:04,600 Speaker 1: we're not here today to talk about the super big galaxies. 279 00:15:04,600 --> 00:15:07,560 Speaker 1: They get enough attention. Let's turn our mental eyes down 280 00:15:07,600 --> 00:15:10,560 Speaker 1: to the other end of the spectrum. Yep, yep, we're 281 00:15:10,600 --> 00:15:13,040 Speaker 1: talking about dwarf galaxies, and like you said, it's the 282 00:15:13,080 --> 00:15:16,560 Speaker 1: case that all galaxies started out as dwarf galaxies, right, 283 00:15:16,600 --> 00:15:20,240 Speaker 1: Like at the beginning of the universe, everything was spread out, 284 00:15:20,240 --> 00:15:23,120 Speaker 1: but then these things started to clump together, and so 285 00:15:23,200 --> 00:15:26,480 Speaker 1: everything started with small galaxies. Yeah, everything started with these 286 00:15:26,600 --> 00:15:29,760 Speaker 1: little fluctuations due to quantum mechanics, a little bit that 287 00:15:29,880 --> 00:15:31,560 Speaker 1: was more dense over here, a little bit that was 288 00:15:31,640 --> 00:15:34,320 Speaker 1: less dense over there, and then gravity did its work 289 00:15:34,320 --> 00:15:37,800 Speaker 1: and pulled that stuff together and made little clumps of 290 00:15:37,840 --> 00:15:40,360 Speaker 1: gas which then turned into stars. And that's how you 291 00:15:40,400 --> 00:15:43,400 Speaker 1: got the first galaxies. So there was like a size 292 00:15:43,480 --> 00:15:46,440 Speaker 1: of those clumps that formed the first galaxies. And you know, 293 00:15:46,520 --> 00:15:48,960 Speaker 1: some of those have merged into bigger galaxies, and some 294 00:15:49,040 --> 00:15:50,560 Speaker 1: of them have not, and some of them are more 295 00:15:50,600 --> 00:15:54,360 Speaker 1: recent and haven't yet merged into other galaxies. So at 296 00:15:54,360 --> 00:15:57,080 Speaker 1: the small end of the scale are those little mini 297 00:15:57,120 --> 00:16:00,560 Speaker 1: galaxies that have not merged or not merged. As many times, 298 00:16:00,720 --> 00:16:03,720 Speaker 1: I wonder if there's like an average size galaxy at 299 00:16:03,720 --> 00:16:06,280 Speaker 1: the beginning of the universe, do you know what I mean? Like, 300 00:16:06,440 --> 00:16:09,960 Speaker 1: the universe presumably was kind of the same everywhere, and 301 00:16:09,920 --> 00:16:13,480 Speaker 1: there's a certain density of stuff, which means that on average, 302 00:16:13,520 --> 00:16:16,560 Speaker 1: there was probably like like every galaxy was almost the 303 00:16:16,600 --> 00:16:19,440 Speaker 1: same size, right, some small size. Yeah, And we can 304 00:16:19,480 --> 00:16:22,680 Speaker 1: actually see this in the cosmic microwave background radiation. We 305 00:16:22,680 --> 00:16:25,680 Speaker 1: can see this pattern of overdensity and under density, and 306 00:16:25,720 --> 00:16:28,320 Speaker 1: we can use that size actually to measure like the 307 00:16:28,400 --> 00:16:31,520 Speaker 1: expansion rate of the universe. We have a whole podcast 308 00:16:31,560 --> 00:16:34,760 Speaker 1: episode about like measuring the curvature of space and the 309 00:16:34,800 --> 00:16:36,960 Speaker 1: history of it, and you can see those kind of 310 00:16:36,960 --> 00:16:41,800 Speaker 1: things expand from an early characteristic quantum fluctuation size lown 311 00:16:41,920 --> 00:16:45,760 Speaker 1: up into something macroscopic, which, as you say, then determines 312 00:16:46,080 --> 00:16:49,160 Speaker 1: basically the size of these initial clumps. Yeah. But again 313 00:16:49,200 --> 00:16:51,920 Speaker 1: it's quantum base, right, So it's totally random. So there 314 00:16:51,920 --> 00:16:53,920 Speaker 1: could have been maybe a spot in the universe but 315 00:16:54,000 --> 00:16:56,920 Speaker 1: that had a big fluctuation which maybe would have made 316 00:16:56,960 --> 00:16:59,680 Speaker 1: a big galaxy out there at the beginning of time. Yeah, 317 00:16:59,720 --> 00:17:02,320 Speaker 1: it random, you're right, and so it's less likely, but 318 00:17:02,360 --> 00:17:05,680 Speaker 1: it's possible to get a larger gravitational collapse an early 319 00:17:05,720 --> 00:17:08,760 Speaker 1: galaxy that started out big. But there's also a typical 320 00:17:08,840 --> 00:17:13,840 Speaker 1: characteristic size where galaxies start, and so that's on the 321 00:17:13,880 --> 00:17:16,680 Speaker 1: little end, and so these dwarf galaxies are basically on 322 00:17:16,680 --> 00:17:20,600 Speaker 1: that smaller end of little gravitational clumps that formed little 323 00:17:20,600 --> 00:17:24,760 Speaker 1: stellar neighborhoods. And so right now we have these galaxies 324 00:17:24,760 --> 00:17:27,200 Speaker 1: and giant structures of galaxies. But it used to be 325 00:17:27,280 --> 00:17:29,720 Speaker 1: the case, maybe at the beginning of the universe, where 326 00:17:30,080 --> 00:17:33,600 Speaker 1: like the entire universe was just kind of evenly distributed 327 00:17:33,640 --> 00:17:36,760 Speaker 1: with tiny little galaxies. Yeah, and these galaxies get to 328 00:17:36,800 --> 00:17:40,520 Speaker 1: be pretty small, like remember the Milky Ways, hundreds of 329 00:17:40,720 --> 00:17:44,600 Speaker 1: billions of stars. Dwarf galaxies can go all the way 330 00:17:44,640 --> 00:17:48,200 Speaker 1: down to like hundreds or thousands of stars, all the 331 00:17:48,240 --> 00:17:51,119 Speaker 1: way up to like several billion stars. So there's an 332 00:17:51,280 --> 00:17:54,520 Speaker 1: enormous spectrum of size there, from really just a handful 333 00:17:54,560 --> 00:17:58,400 Speaker 1: of stars all the way up to billions of stars. Mm. Interesting. 334 00:17:58,440 --> 00:18:01,320 Speaker 1: All right, let's get more into actual dwarf galaxies and 335 00:18:01,560 --> 00:18:03,720 Speaker 1: what they can tell us about dark matter and the 336 00:18:03,880 --> 00:18:06,960 Speaker 1: rest of how the universe form. But first let's take 337 00:18:07,000 --> 00:18:22,200 Speaker 1: a quick break. All right, we're talking about dwarf galaxies, 338 00:18:22,280 --> 00:18:24,680 Speaker 1: and we talked a little bit about how basically dwarf 339 00:18:24,720 --> 00:18:28,120 Speaker 1: galaxies were the og galaxies in the universe, right like, 340 00:18:28,400 --> 00:18:31,920 Speaker 1: at the beginning of time, every galaxy was a dwarf back. Yeah, 341 00:18:31,920 --> 00:18:34,840 Speaker 1: there may have been some larger galaxies formed randomly, as 342 00:18:34,880 --> 00:18:38,439 Speaker 1: you said, But the original galaxies, yeah, we're all dwarf galaxies, 343 00:18:38,480 --> 00:18:42,119 Speaker 1: that's how it all began, and they usually kind of 344 00:18:42,160 --> 00:18:44,239 Speaker 1: have a fuzzy shape to them, right, They don't have 345 00:18:44,280 --> 00:18:48,080 Speaker 1: maybe this nice spiral shape or form that the Milky 346 00:18:48,080 --> 00:18:50,960 Speaker 1: Way has. It's actually interesting and really subtle point there, 347 00:18:51,040 --> 00:18:53,800 Speaker 1: because if you have an initial clump of stuff that 348 00:18:53,920 --> 00:18:57,399 Speaker 1: collapses under gravity, it tends to form a disk, and 349 00:18:57,440 --> 00:18:59,639 Speaker 1: it forms a disc because it's spinning, and it's spinning 350 00:18:59,680 --> 00:19:02,840 Speaker 1: like around some particular axis. Gravity can squeeze it down 351 00:19:02,840 --> 00:19:06,160 Speaker 1: sort of along that axis, but on the plane perpendicular 352 00:19:06,160 --> 00:19:08,280 Speaker 1: to it, it can't squeeze it down as much because 353 00:19:08,280 --> 00:19:11,399 Speaker 1: it's still spinning and it retains that angular momentum. So 354 00:19:11,440 --> 00:19:13,680 Speaker 1: if you have just like an initial spinning blob of stuff, 355 00:19:13,720 --> 00:19:16,560 Speaker 1: it tends to form a disc. Now, when dwarf galaxies 356 00:19:16,560 --> 00:19:18,919 Speaker 1: merge together to make bigger galaxies, then you have like 357 00:19:19,000 --> 00:19:21,359 Speaker 1: disc spinning in lots of different directions, and you end 358 00:19:21,440 --> 00:19:25,480 Speaker 1: up with like more ellipsoid galaxies which eventually later then 359 00:19:25,520 --> 00:19:29,080 Speaker 1: also collapse into like some big overall disc, which is 360 00:19:29,080 --> 00:19:33,160 Speaker 1: why like the Milky Way is mostly a disc. All right. Well, 361 00:19:33,160 --> 00:19:35,439 Speaker 1: then like how many. I guess that question is like 362 00:19:35,440 --> 00:19:38,119 Speaker 1: how many dwarf galaxies do you need to come together 363 00:19:38,440 --> 00:19:40,840 Speaker 1: to make a galaxy like the Milkyway, Because you're saying 364 00:19:40,840 --> 00:19:43,760 Speaker 1: the Milky Way probably formed out of dwarf galaxies coming together, right, 365 00:19:43,840 --> 00:19:46,159 Speaker 1: I'm just wondering how many it takes. Yeah, I mean 366 00:19:46,200 --> 00:19:50,320 Speaker 1: if dwarf galaxies start out as a few thousand stars, right, 367 00:19:50,320 --> 00:19:54,440 Speaker 1: and the Milky Way has a few hundred billion stars, 368 00:19:54,840 --> 00:19:57,320 Speaker 1: then that means that the Milky Way might be like 369 00:19:57,440 --> 00:20:01,920 Speaker 1: a million dwarf galaxies all smooth together into one big galaxy. 370 00:20:02,000 --> 00:20:04,240 Speaker 1: But you said the range is between like a dwarf 371 00:20:04,280 --> 00:20:07,640 Speaker 1: galaxy is between a thousand and several billion. Yeah, Well, 372 00:20:07,680 --> 00:20:09,679 Speaker 1: you know, this is one of those sort of artificial 373 00:20:09,680 --> 00:20:12,640 Speaker 1: distinctions in astronomy, like what do you call a galaxy 374 00:20:12,680 --> 00:20:14,479 Speaker 1: and what do you call a dwarf galaxy. There's this 375 00:20:14,560 --> 00:20:17,440 Speaker 1: threshold of a few Above a few billion or a 376 00:20:17,480 --> 00:20:20,960 Speaker 1: few tens of billions of stars, it's called a galaxy, 377 00:20:21,200 --> 00:20:23,960 Speaker 1: and below that it's called a dwarf galaxy. For example, 378 00:20:24,080 --> 00:20:27,600 Speaker 1: the large Magellanic cloud is orbiting the Milky Way and 379 00:20:27,600 --> 00:20:30,400 Speaker 1: it has like thirty billion stars in it. Some people 380 00:20:30,440 --> 00:20:32,600 Speaker 1: call it a dwarf galaxy. Some people say, no, no, 381 00:20:32,720 --> 00:20:35,000 Speaker 1: it's its own galaxy, and so that's a bit of 382 00:20:35,000 --> 00:20:36,760 Speaker 1: an artificial distinction. But if you want to go like 383 00:20:36,840 --> 00:20:39,560 Speaker 1: all the way back to the og galaxies out of 384 00:20:39,600 --> 00:20:41,720 Speaker 1: which everything was built, then those are all going to 385 00:20:41,760 --> 00:20:44,359 Speaker 1: start out pretty small. So if those are like a 386 00:20:44,400 --> 00:20:46,720 Speaker 1: few thousand stars, then it's going to take millions of 387 00:20:46,760 --> 00:20:50,200 Speaker 1: those to make a milky way. I feel like, if 388 00:20:50,240 --> 00:20:52,640 Speaker 1: you have a thousand stars, maybe you shouldn't be called 389 00:20:52,640 --> 00:20:56,159 Speaker 1: a galaxy, you know, that's such a that's more like 390 00:20:56,200 --> 00:20:58,600 Speaker 1: a I don't know, like a star neighborhood or something 391 00:20:59,040 --> 00:21:02,520 Speaker 1: star clump associated stars. That's the bias, right, that's us 392 00:21:02,600 --> 00:21:06,560 Speaker 1: looking at our neighborhood and observing other galaxies. But something 393 00:21:06,600 --> 00:21:09,640 Speaker 1: we learn as we develop better tools is to see 394 00:21:09,720 --> 00:21:12,040 Speaker 1: fainter stuff, is to discover the stuff that is not 395 00:21:12,200 --> 00:21:14,960 Speaker 1: as easy to spot. And the whole history of science 396 00:21:15,359 --> 00:21:18,439 Speaker 1: is us drawing big conclusions from the stuff we first 397 00:21:18,480 --> 00:21:21,800 Speaker 1: see and then discovering, oh, that wasn't representative. It turns 398 00:21:21,800 --> 00:21:24,160 Speaker 1: out we need to revise our whole picture of how 399 00:21:24,200 --> 00:21:27,080 Speaker 1: things work. And so we've been seeing the biggest, brightest, 400 00:21:27,119 --> 00:21:30,160 Speaker 1: most exciting galaxies, but there the whole spectrum of other 401 00:21:30,240 --> 00:21:31,760 Speaker 1: kind of stuff out there, whether you want to call 402 00:21:31,800 --> 00:21:35,320 Speaker 1: it a galaxy or mini galaxy or galaxy no or 403 00:21:35,440 --> 00:21:38,800 Speaker 1: dwarf galaxy. You know, that's just the name. You mean, Like, 404 00:21:38,840 --> 00:21:40,840 Speaker 1: there could be aliens out there in one of these 405 00:21:40,880 --> 00:21:43,480 Speaker 1: megan galaxies looking at us and saying, that's not a 406 00:21:43,520 --> 00:21:47,360 Speaker 1: real galaxy. It only has four hundred billion stars. That's 407 00:21:47,400 --> 00:21:50,720 Speaker 1: nothing exactly. Remember if we demote other galaxies that they 408 00:21:50,760 --> 00:21:52,760 Speaker 1: might come for us. Yeah, but you're saying so, you're 409 00:21:52,760 --> 00:21:55,919 Speaker 1: saying that our galaxy, the Milky Way, it probably is 410 00:21:55,960 --> 00:21:59,159 Speaker 1: made up of hundreds of these original dwarf galaxies that 411 00:21:59,240 --> 00:22:02,639 Speaker 1: the universe started with. Hundreds or thousands or maybe even 412 00:22:02,760 --> 00:22:06,639 Speaker 1: millions of dwarf galaxies have been smooshed together. Like the 413 00:22:06,720 --> 00:22:09,200 Speaker 1: stars that are in the Milky Way did not all 414 00:22:09,280 --> 00:22:12,120 Speaker 1: start in the same part of the universe. They all 415 00:22:12,119 --> 00:22:16,199 Speaker 1: came together after they already formed clumps of stars. So 416 00:22:16,240 --> 00:22:17,840 Speaker 1: all the stars in the Milky Way did not form 417 00:22:17,880 --> 00:22:20,159 Speaker 1: out of the same big gas cloud. You had like 418 00:22:20,520 --> 00:22:23,840 Speaker 1: millions of different gas clouds that made millions of little 419 00:22:23,880 --> 00:22:27,639 Speaker 1: pockets of stars which then formed together later into a 420 00:22:27,640 --> 00:22:30,399 Speaker 1: bigger galaxy. You mean they were all sort of clumped 421 00:22:30,400 --> 00:22:33,480 Speaker 1: together initially maybe is that what you're saying? But then 422 00:22:33,560 --> 00:22:37,800 Speaker 1: within that giant cloud, little galaxies form that then eventually 423 00:22:38,040 --> 00:22:40,760 Speaker 1: clumped together. Well, I mean they clumped together eventually, the 424 00:22:40,800 --> 00:22:43,480 Speaker 1: same way that for example, Andromeda and the Milky Way 425 00:22:43,600 --> 00:22:47,320 Speaker 1: will eventually merge in a few billion years. Gravity is 426 00:22:47,359 --> 00:22:50,600 Speaker 1: inexorably pulling us together and we will form some big 427 00:22:50,640 --> 00:22:52,679 Speaker 1: combined galaxy. I don't know what you call it, like 428 00:22:52,720 --> 00:22:57,639 Speaker 1: the Andromeda Way or Milky Andromeda or something Vanilla Andromeda. 429 00:22:58,640 --> 00:23:00,879 Speaker 1: I vote for vanilla and drama in tribute to the 430 00:23:00,920 --> 00:23:04,879 Speaker 1: greatest flavor. Right. Sounds good? And then you can ask like, well, 431 00:23:04,920 --> 00:23:07,080 Speaker 1: you know, did the Milky waan Andromeda? Did they form 432 00:23:07,160 --> 00:23:09,719 Speaker 1: together out of the same big clump. Well, their gravitational 433 00:23:09,760 --> 00:23:12,040 Speaker 1: future is secure that they will eventually be together, but 434 00:23:12,200 --> 00:23:14,840 Speaker 1: really they formed separately and then came together. And that 435 00:23:15,080 --> 00:23:18,320 Speaker 1: same idea applies to all the dwarf galaxies that formed 436 00:23:18,320 --> 00:23:21,320 Speaker 1: the Milky Way and the dwarf galaxies that formed Andromeda. 437 00:23:21,400 --> 00:23:24,119 Speaker 1: They sort of formed separately and then later came together 438 00:23:24,240 --> 00:23:28,359 Speaker 1: to make bigger galaxies. So then has enough time gone 439 00:23:28,359 --> 00:23:30,919 Speaker 1: by to explain how our gas they form out of 440 00:23:30,960 --> 00:23:33,879 Speaker 1: maybe millions of little galaxies like I know, that's a 441 00:23:33,880 --> 00:23:37,119 Speaker 1: big mystery with black holes. Right, Yeah, that's a great question. 442 00:23:37,160 --> 00:23:39,520 Speaker 1: And that's actually one of the great triumphs of dark 443 00:23:39,560 --> 00:23:42,560 Speaker 1: matter is that when we do simulations of our universe 444 00:23:42,600 --> 00:23:44,879 Speaker 1: and we say, here's so much dark matter there was, 445 00:23:44,920 --> 00:23:47,280 Speaker 1: and here's some quantum fluctuations, and then we just like 446 00:23:47,400 --> 00:23:51,600 Speaker 1: run the clock forward, we can actually reproduce the large 447 00:23:51,600 --> 00:23:55,119 Speaker 1: scale structure of the universe, formation of the big galaxies 448 00:23:55,160 --> 00:23:57,760 Speaker 1: that we see. And actually the bigger galaxies we see 449 00:23:57,760 --> 00:24:00,000 Speaker 1: do appear in our simulations. But as we'll talk about 450 00:24:00,080 --> 00:24:02,680 Speaker 1: later in the podcast, the dwarf galaxies, we don't really 451 00:24:02,720 --> 00:24:05,080 Speaker 1: understand why there aren't more of them. So we do 452 00:24:05,160 --> 00:24:08,160 Speaker 1: understand some of it, but not all of it. Interesting, 453 00:24:08,200 --> 00:24:11,359 Speaker 1: are there still dwarf galaxies merging into our Milky Way 454 00:24:11,400 --> 00:24:13,840 Speaker 1: galaxy or within our Milky Way galaxy? Or are we 455 00:24:13,880 --> 00:24:17,160 Speaker 1: pretty much like just one big unified family right now? 456 00:24:17,200 --> 00:24:19,640 Speaker 1: There are so many dwarf galaxies still out there right now, 457 00:24:19,680 --> 00:24:22,399 Speaker 1: A bunch of them are orbiting the Milky Way, right 458 00:24:22,440 --> 00:24:25,199 Speaker 1: which means eventually they might get slurped up by the 459 00:24:25,240 --> 00:24:28,720 Speaker 1: Milky Way. Wait, what we have like a galaxy system? 460 00:24:28,760 --> 00:24:30,720 Speaker 1: Oh yeah, like we have our galaxy, and we have 461 00:24:30,800 --> 00:24:35,160 Speaker 1: little galaxies orbiting around this. Yeah, we have satellite galaxies, right, 462 00:24:35,240 --> 00:24:39,040 Speaker 1: little dwarf galaxies orbiting the Milky Way, trapped by our 463 00:24:39,080 --> 00:24:42,400 Speaker 1: gravity and eventually they'll gets slurped up. WHOA, how many 464 00:24:42,440 --> 00:24:45,720 Speaker 1: satellite galaxies do we have? That's an interesting and complicated question. 465 00:24:45,840 --> 00:24:49,399 Speaker 1: We have something around a couple dozen satellite galaxies that 466 00:24:49,480 --> 00:24:52,879 Speaker 1: we've discovered, and one of the big questions about the 467 00:24:52,920 --> 00:24:56,399 Speaker 1: research right now is why don't we have more. So 468 00:24:56,440 --> 00:24:59,399 Speaker 1: if you run these simulations, they suggest that you should 469 00:24:59,440 --> 00:25:01,679 Speaker 1: get ga taxies about the size of the Milky Way, 470 00:25:01,800 --> 00:25:03,960 Speaker 1: and we do, and that all makes sense, but they 471 00:25:04,040 --> 00:25:06,679 Speaker 1: also suggest that the Milky Way should have a lot 472 00:25:06,720 --> 00:25:11,240 Speaker 1: more dwarf galaxy satellites. There should be like five hundred 473 00:25:11,280 --> 00:25:13,440 Speaker 1: of them orbiting the Milky Way, but we only see 474 00:25:13,480 --> 00:25:15,520 Speaker 1: a couple dozen. And that's one of the things people 475 00:25:15,520 --> 00:25:18,639 Speaker 1: are still confused about. And that's why dwarf galaxies are 476 00:25:18,680 --> 00:25:21,399 Speaker 1: so interesting, because they're one of the things that remain 477 00:25:21,680 --> 00:25:25,560 Speaker 1: not well understood interesting. So you're saying that, like, we 478 00:25:25,640 --> 00:25:27,720 Speaker 1: run a simulation of the universe based on what we 479 00:25:27,800 --> 00:25:30,440 Speaker 1: know and then explains the big stuff out there, like 480 00:25:30,480 --> 00:25:35,320 Speaker 1: the galaxy superclusters and the bubbles and the walls of superclusters. 481 00:25:35,400 --> 00:25:38,119 Speaker 1: But it doesn't match what we see kind of at 482 00:25:38,119 --> 00:25:41,400 Speaker 1: the local level around us, around our galaxy. Yeah, exactly. 483 00:25:41,440 --> 00:25:44,200 Speaker 1: It suggests that if you're going to have big galaxies 484 00:25:44,240 --> 00:25:46,560 Speaker 1: that comes out of formations of a bunch of little ones, 485 00:25:46,920 --> 00:25:49,439 Speaker 1: but not all the little ones should get slurped up 486 00:25:49,480 --> 00:25:51,399 Speaker 1: into the big ones, that you should have lots and 487 00:25:51,480 --> 00:25:55,760 Speaker 1: lots of little galaxies still left over orbiting the bigger galaxies. 488 00:25:55,800 --> 00:25:57,680 Speaker 1: But when we look out into the night sky, we 489 00:25:57,720 --> 00:26:00,200 Speaker 1: just don't see them like we look for them, try 490 00:26:00,200 --> 00:26:02,040 Speaker 1: to spot them. We've seen some of them, but we 491 00:26:02,040 --> 00:26:04,600 Speaker 1: don't see as many as we expect. It sounds like 492 00:26:04,600 --> 00:26:08,400 Speaker 1: there's something wrong with the simulation, not necessarily with the universe. 493 00:26:09,600 --> 00:26:13,680 Speaker 1: You know, the universe has to follow our program man. Yeah, 494 00:26:13,720 --> 00:26:16,320 Speaker 1: that's what I'm saying. I don't think the universe cares. No, 495 00:26:16,440 --> 00:26:18,800 Speaker 1: it's not that the universe has done something wrong and 496 00:26:18,920 --> 00:26:21,159 Speaker 1: needs to be chastised or something. This is just the 497 00:26:21,200 --> 00:26:23,359 Speaker 1: process we have. We think we understand the rules that 498 00:26:23,400 --> 00:26:26,159 Speaker 1: control how things happen, and so then we do a 499 00:26:26,160 --> 00:26:28,760 Speaker 1: bunch of simulations to say, what do the rules predict 500 00:26:28,800 --> 00:26:31,119 Speaker 1: and if they predict something we don't see, that means 501 00:26:31,119 --> 00:26:34,120 Speaker 1: obviously something is wrong with the simulation, but the question 502 00:26:34,320 --> 00:26:37,200 Speaker 1: is what or the other thing is maybe something is 503 00:26:37,240 --> 00:26:39,360 Speaker 1: wrong with what we're seeing, like maybe we're just not 504 00:26:39,520 --> 00:26:43,720 Speaker 1: seeing everything that's out there. Dwarf galaxies are tricky to 505 00:26:43,920 --> 00:26:46,920 Speaker 1: spot because they're small. They only have hundred thousands or 506 00:26:46,960 --> 00:26:49,520 Speaker 1: maybe millions of stars in them, so they are much 507 00:26:49,600 --> 00:26:53,359 Speaker 1: fainter than other galaxies, which make them more challenging to spot. 508 00:26:54,160 --> 00:26:56,879 Speaker 1: So we were expecting from the simulations to see about 509 00:26:56,920 --> 00:26:59,800 Speaker 1: five hundred dwarf galaxies orbiting the Milky Way, but we've 510 00:26:59,800 --> 00:27:02,960 Speaker 1: only seen about twelve. And you're saying, like, I wonder 511 00:27:03,000 --> 00:27:05,000 Speaker 1: if you could maybe even see them from our point 512 00:27:05,040 --> 00:27:07,760 Speaker 1: of view, right, Like they're so small, maybe to us 513 00:27:07,760 --> 00:27:10,280 Speaker 1: they just look like a little cluster of stars, not 514 00:27:10,320 --> 00:27:13,040 Speaker 1: necessarily a whole other galaxy. It is complicated by the 515 00:27:13,040 --> 00:27:15,200 Speaker 1: fact that we are inside the Milky Way, which makes 516 00:27:15,240 --> 00:27:17,400 Speaker 1: it harder to see out of the Milky Way because 517 00:27:17,400 --> 00:27:20,040 Speaker 1: there's so many stars and gas and dust in between. 518 00:27:20,160 --> 00:27:22,640 Speaker 1: They have taken that into account, like how many galaxies 519 00:27:22,640 --> 00:27:25,840 Speaker 1: should we have seen from our point of view that 520 00:27:26,000 --> 00:27:28,719 Speaker 1: they have factored in something that they're not sure about 521 00:27:29,080 --> 00:27:32,439 Speaker 1: has to do with the dark matter in these dwarf galaxies. Like, 522 00:27:32,720 --> 00:27:34,919 Speaker 1: we also suspect, and I want to dig into this 523 00:27:34,960 --> 00:27:37,800 Speaker 1: in a minute, that these dwarf galaxies are much heavier 524 00:27:37,880 --> 00:27:41,480 Speaker 1: in dark matter than in normal matter. A typical galaxy 525 00:27:41,600 --> 00:27:45,359 Speaker 1: is about eighty five percent dark matter fifteen percent normal matter. 526 00:27:45,760 --> 00:27:48,720 Speaker 1: The Milky Way is a bit above that, like ninety 527 00:27:48,760 --> 00:27:52,560 Speaker 1: percent dark matter ten percent normal matter. But these dwarf 528 00:27:52,600 --> 00:27:55,879 Speaker 1: galaxies might be overwhelmingly dark matter. They might have a 529 00:27:55,880 --> 00:27:58,840 Speaker 1: lot more dark matter in them than normal matter, which 530 00:27:58,960 --> 00:28:02,359 Speaker 1: of course make them harder to spot. Now, this mystery 531 00:28:02,400 --> 00:28:05,280 Speaker 1: about not seeing enough dwarf galaxies around the Milky Way, 532 00:28:05,359 --> 00:28:07,840 Speaker 1: is that also true for other galaxies? Like if you 533 00:28:07,840 --> 00:28:11,719 Speaker 1: look at the Andromeda galaxy, do you also see less 534 00:28:11,920 --> 00:28:15,080 Speaker 1: or fewer dwarf galaxies than you think you would? Yeah, 535 00:28:15,119 --> 00:28:17,920 Speaker 1: it's a problem everywhere. It's harder to study for more 536 00:28:17,960 --> 00:28:21,919 Speaker 1: distant galaxies because they aren't more distant, and these galaxies 537 00:28:21,960 --> 00:28:25,280 Speaker 1: are small. So you know, our observations of dwarf galaxies 538 00:28:25,280 --> 00:28:28,320 Speaker 1: around Andromeda are not even as good as our observations 539 00:28:28,400 --> 00:28:31,439 Speaker 1: of dwarf galaxies around the Milky Way, which are already 540 00:28:31,560 --> 00:28:34,080 Speaker 1: very challenging to see. So the Milky Way is sort 541 00:28:34,080 --> 00:28:36,440 Speaker 1: of like the best laboratory for studying this. But yeah, 542 00:28:36,480 --> 00:28:39,440 Speaker 1: we see similar stuff in Andromeda. Beyond that, it's just 543 00:28:39,520 --> 00:28:42,000 Speaker 1: too difficult to study. I guess it's kind of like 544 00:28:42,040 --> 00:28:45,680 Speaker 1: trying to detect the wisps of smoke around, like a 545 00:28:45,760 --> 00:28:48,120 Speaker 1: giant cloud of smoke. Right, that's kind of what these 546 00:28:48,160 --> 00:28:50,840 Speaker 1: galaxies look like from far exactly, and it's not always 547 00:28:50,840 --> 00:28:53,240 Speaker 1: easy to tell, like where is the edge of a galaxy? 548 00:28:53,320 --> 00:28:55,600 Speaker 1: And is that the count is a dwarf galaxy or 549 00:28:55,680 --> 00:28:59,080 Speaker 1: is it already falling into the main galaxy right against 550 00:28:59,200 --> 00:29:02,200 Speaker 1: all sorts of distant Oh, I see that's the real mystery. 551 00:29:02,320 --> 00:29:05,040 Speaker 1: I just change how you call them, then done. You 552 00:29:05,120 --> 00:29:07,960 Speaker 1: can check off that box. No, it doesn't matter what 553 00:29:08,000 --> 00:29:10,760 Speaker 1: you call them, because there's just a disagreement about the 554 00:29:10,840 --> 00:29:14,640 Speaker 1: distribution of stars in our simulations and what we see 555 00:29:14,680 --> 00:29:17,040 Speaker 1: out there in the universe. But a lot of astronomers 556 00:29:17,080 --> 00:29:20,360 Speaker 1: think that probably this will be resolved if we improve 557 00:29:20,400 --> 00:29:23,880 Speaker 1: our abilities to discover these dwarf galaxies. For example, recently 558 00:29:24,120 --> 00:29:27,680 Speaker 1: they found eight new Milky Way dwarf galaxies that they 559 00:29:27,680 --> 00:29:30,719 Speaker 1: hadn't spotted before because they are ultra faint because they 560 00:29:30,720 --> 00:29:34,120 Speaker 1: are more than ninety nine point nine percent dark matter. 561 00:29:34,400 --> 00:29:37,920 Speaker 1: They're basically dark matter galaxies with a little sprinkling of 562 00:29:37,960 --> 00:29:41,080 Speaker 1: stars in them. WHOA wait, I feel like now you're 563 00:29:41,120 --> 00:29:44,880 Speaker 1: getting into the definition of a galaxy itself. Like are 564 00:29:44,880 --> 00:29:47,240 Speaker 1: you saying, like a bunch of dark matter with a 565 00:29:47,280 --> 00:29:50,960 Speaker 1: few stars in it, that's a galaxy. Stick, that's a 566 00:29:51,080 --> 00:29:54,560 Speaker 1: galaxy according to astronomers. Yeah, it has the mass, right, 567 00:29:54,560 --> 00:29:56,400 Speaker 1: it has stars in it, so yeah, they call that 568 00:29:56,440 --> 00:29:59,280 Speaker 1: a galaxy. I guess maybe the definition then is just 569 00:29:59,360 --> 00:30:02,880 Speaker 1: like a stuff out there in space that's maybe separate 570 00:30:02,960 --> 00:30:05,240 Speaker 1: from other clubs of stuff. Yeah, But then you get 571 00:30:05,240 --> 00:30:07,480 Speaker 1: in the question like, what do you call a globular cluster? 572 00:30:07,760 --> 00:30:10,080 Speaker 1: Why is that not a dwarf galaxy? Why is it 573 00:30:10,120 --> 00:30:12,560 Speaker 1: a cluster? Exactly right, That's what I would That's why 574 00:30:12,600 --> 00:30:16,280 Speaker 1: I'm confused. Now, Well, welcome the club. Astronomy is a 575 00:30:16,280 --> 00:30:18,920 Speaker 1: disaster when it comes to naming things. And that comes 576 00:30:18,920 --> 00:30:20,880 Speaker 1: from a particle physicist, and I know that we have 577 00:30:20,920 --> 00:30:23,400 Speaker 1: no high ground when it comes to naming things. Yeah, 578 00:30:23,480 --> 00:30:26,520 Speaker 1: I guess it's hard to name things in general, right, 579 00:30:26,560 --> 00:30:28,880 Speaker 1: It's hard to name your kids. I can only imagine 580 00:30:28,960 --> 00:30:31,400 Speaker 1: naming the entire universe. Well, the real challenge here is 581 00:30:31,440 --> 00:30:33,360 Speaker 1: that a lot of this is historical. You know, we 582 00:30:33,400 --> 00:30:36,920 Speaker 1: didn't always understand the connections between things. We saw stuff 583 00:30:36,920 --> 00:30:39,560 Speaker 1: in the sky, we gave it different names. Later we realized, oh, 584 00:30:39,560 --> 00:30:41,480 Speaker 1: this is really another kind of that. You know, even 585 00:30:41,520 --> 00:30:43,240 Speaker 1: if you just look in our solar system, you know, 586 00:30:43,280 --> 00:30:45,840 Speaker 1: we have like comets and asteroids, and then we have 587 00:30:45,960 --> 00:30:49,680 Speaker 1: like centaurs, which are sort of like between comets and asteroids. 588 00:30:50,040 --> 00:30:52,160 Speaker 1: We have planets, and we have moons, and like, you know, 589 00:30:52,200 --> 00:30:55,400 Speaker 1: the distinctions between these things are fuzzy. What's really going 590 00:30:55,440 --> 00:30:57,880 Speaker 1: on is that you have a whole spectrum of stuff 591 00:30:57,880 --> 00:31:01,000 Speaker 1: out there, from big to small and every thing in between. 592 00:31:01,240 --> 00:31:04,560 Speaker 1: So the distinctions between things are sort of artificial labels 593 00:31:04,560 --> 00:31:06,520 Speaker 1: that we are just putting on stuff because what we 594 00:31:06,600 --> 00:31:10,640 Speaker 1: historically saw first, what we sort of originally called things. 595 00:31:10,680 --> 00:31:13,480 Speaker 1: The truth is that there's a smooth spectrum of all 596 00:31:13,520 --> 00:31:15,640 Speaker 1: sorts of stuff out there. Sounds like you just need 597 00:31:15,720 --> 00:31:19,479 Speaker 1: to call everything stuff, like a lot of galaxy. It's 598 00:31:19,520 --> 00:31:21,880 Speaker 1: just stuff. That's not a black hole, it's just stuff. 599 00:31:22,320 --> 00:31:25,160 Speaker 1: If I usually change your name from physicists to stuffists, 600 00:31:25,400 --> 00:31:28,200 Speaker 1: stuff is this, yeah, exactly, I'm just you can be stuffy. 601 00:31:28,240 --> 00:31:29,800 Speaker 1: Stuff is this? Yeah, I'm just trying to stuff as 602 00:31:29,880 --> 00:31:32,440 Speaker 1: much knowledge in my mind about stuff. Basically, you know, 603 00:31:32,480 --> 00:31:35,920 Speaker 1: it's different from like biology. Cats and dogs really are 604 00:31:35,960 --> 00:31:38,800 Speaker 1: different things. There's not an entire spectrum of every creature 605 00:31:38,880 --> 00:31:41,080 Speaker 1: between a cat and a dog. That doesn't exist. But 606 00:31:41,160 --> 00:31:43,320 Speaker 1: I think out there in the universe there really is 607 00:31:43,400 --> 00:31:46,400 Speaker 1: like every kind of thing between every other kind of thing. 608 00:31:46,560 --> 00:31:48,480 Speaker 1: So there's a whole spectrum of stuff out there is 609 00:31:48,520 --> 00:31:52,600 Speaker 1: just waiting to be discovered. Interesting. All right, Well, let's 610 00:31:52,640 --> 00:31:56,040 Speaker 1: get a little bit deeper into this connection between dark 611 00:31:56,080 --> 00:31:59,360 Speaker 1: matter and dwarf galaxies and how maybe dwarf galaxies can 612 00:31:59,360 --> 00:32:02,760 Speaker 1: help us understand or finally figure out what dark matter is. 613 00:32:03,720 --> 00:32:18,680 Speaker 1: But first let's take another quick break. All right, we're 614 00:32:18,720 --> 00:32:22,960 Speaker 1: talking about dwarf galaxies. And it's pretty interesting that what 615 00:32:23,120 --> 00:32:25,440 Speaker 1: you said earlier that like a clump of dark matter, 616 00:32:25,560 --> 00:32:27,920 Speaker 1: which is a few sprinkles of stars, you would still 617 00:32:27,960 --> 00:32:31,200 Speaker 1: call that a galaxy. I would still call that a galaxy. 618 00:32:31,440 --> 00:32:34,640 Speaker 1: I mean, think about where that came from. Originally, you 619 00:32:34,760 --> 00:32:37,440 Speaker 1: had a clump of stuff in the very early universe, 620 00:32:37,480 --> 00:32:40,840 Speaker 1: a tiny little bit denser than everything else. Mostly that 621 00:32:40,920 --> 00:32:42,960 Speaker 1: means the dark matter because it was more dark matter 622 00:32:43,000 --> 00:32:45,480 Speaker 1: than everything else that dark matter makes like a little 623 00:32:45,520 --> 00:32:48,320 Speaker 1: we call it a gravitational well. Everything likes to roll 624 00:32:48,480 --> 00:32:54,040 Speaker 1: downhill towards lower gravitational potential. Gravity gathers stuff together, and 625 00:32:54,120 --> 00:32:57,520 Speaker 1: so every little gravitational well gathered together a blob of 626 00:32:57,640 --> 00:33:01,200 Speaker 1: dark matter and a blob of normal matter you know, gas, etc. 627 00:33:01,600 --> 00:33:04,520 Speaker 1: And that led to star formation. And so it's because 628 00:33:04,680 --> 00:33:07,680 Speaker 1: of dark matter that gas clumped together and made the 629 00:33:07,720 --> 00:33:10,680 Speaker 1: first stars in the early universe. And so every sort 630 00:33:10,680 --> 00:33:13,719 Speaker 1: of like original og clump there. I guess we call 631 00:33:13,760 --> 00:33:16,480 Speaker 1: a dwarf galaxy. I see, Okay, I guess it's kind 632 00:33:16,480 --> 00:33:19,520 Speaker 1: of also like our galaxies mostly dark matter too, Like 633 00:33:19,920 --> 00:33:22,520 Speaker 1: the Milky Way is mostly dark matter with a few 634 00:33:22,520 --> 00:33:25,200 Speaker 1: sprinkles of stars, like by mass, where the Milky Ways 635 00:33:25,280 --> 00:33:28,840 Speaker 1: with fifteen percent Yeah, exactly. On average, the universe is 636 00:33:28,880 --> 00:33:32,080 Speaker 1: about eighty percent dark matter in terms of mass, and 637 00:33:32,120 --> 00:33:35,160 Speaker 1: so everything out there is mostly dark matter with a 638 00:33:35,240 --> 00:33:37,840 Speaker 1: sprinkling of stars. Wait, are you saying the Milky Way 639 00:33:37,880 --> 00:33:40,680 Speaker 1: should actually be called the milk chocolate the way. It's 640 00:33:40,720 --> 00:33:42,880 Speaker 1: more like the hot Cocoa Way, right, It's really a 641 00:33:43,320 --> 00:33:46,560 Speaker 1: river of dark deliciousness with a few sprinkles of marshmallows, 642 00:33:46,560 --> 00:33:48,680 Speaker 1: like the stars are the marshmallows on top of the 643 00:33:48,760 --> 00:33:52,880 Speaker 1: dark matter hot coco give means more. But what's fascinating 644 00:33:52,960 --> 00:33:55,760 Speaker 1: is that these dwarf galaxies have much more dark matter 645 00:33:56,080 --> 00:33:58,680 Speaker 1: than typical Like they can be up to ninety nine 646 00:33:58,680 --> 00:34:02,120 Speaker 1: point ninety nine percent dark matter. Right, All dwarf galaxies 647 00:34:02,160 --> 00:34:04,840 Speaker 1: are just these last few that we found. Most dwarf 648 00:34:04,840 --> 00:34:08,160 Speaker 1: galaxies are overwhelmingly dark matter. There's are a few that 649 00:34:08,200 --> 00:34:10,279 Speaker 1: are like satellites of the Milky Way that have had 650 00:34:10,280 --> 00:34:12,480 Speaker 1: their dark matter stripped out of them, but the great 651 00:34:12,520 --> 00:34:15,759 Speaker 1: majority of them are overwhelmingly dark matter. It's just sort 652 00:34:15,760 --> 00:34:18,520 Speaker 1: of like the size of that clump of stuff tends 653 00:34:18,560 --> 00:34:21,799 Speaker 1: to have fewer stars. Really, why is that if you 654 00:34:21,800 --> 00:34:24,560 Speaker 1: have a smaller clump of stuff, you have less gravity 655 00:34:24,600 --> 00:34:28,440 Speaker 1: sort of holding those initial stars together because stars are 656 00:34:28,480 --> 00:34:31,239 Speaker 1: sort of poison to other stars. Like, what happens when 657 00:34:31,280 --> 00:34:33,719 Speaker 1: you form stars is you get a bunch of radiations 658 00:34:33,719 --> 00:34:36,319 Speaker 1: shooting out from that star, and that tends to heat 659 00:34:36,400 --> 00:34:38,520 Speaker 1: up and blow out all the gas that you need 660 00:34:38,560 --> 00:34:41,080 Speaker 1: to make stars. So remember to make a star, you 661 00:34:41,120 --> 00:34:43,839 Speaker 1: need a blob of cold gas. The gas can't be 662 00:34:43,840 --> 00:34:46,920 Speaker 1: like moving around too fast or gravity which is super 663 00:34:46,960 --> 00:34:49,400 Speaker 1: weak won't have a chance to suck it together. So 664 00:34:49,440 --> 00:34:52,400 Speaker 1: as soon as you start forming stars, then those stars 665 00:34:52,400 --> 00:34:54,759 Speaker 1: like push out all the other gas. And then as 666 00:34:54,760 --> 00:34:57,560 Speaker 1: soon as you have the first supernova, it basically blows 667 00:34:57,600 --> 00:35:00,719 Speaker 1: out all the gas from a dwarf galaxy. But if 668 00:35:00,760 --> 00:35:03,280 Speaker 1: you have a big enough clump, then they can retain 669 00:35:03,480 --> 00:35:06,840 Speaker 1: that gas anyway. Right, So as you're sort of serving 670 00:35:06,840 --> 00:35:09,440 Speaker 1: of gravity, you get smaller, you get too small to 671 00:35:09,520 --> 00:35:13,000 Speaker 1: sort of overcome these supernova and these other effects that 672 00:35:13,040 --> 00:35:16,040 Speaker 1: are killing your star formation. Oh I see, because I 673 00:35:16,080 --> 00:35:19,359 Speaker 1: guess when a star explodes in a supernova, the dark 674 00:35:19,400 --> 00:35:23,080 Speaker 1: matter doesn't care, right, Like a star will explode, but 675 00:35:23,120 --> 00:35:25,920 Speaker 1: the dark messines it doesn't interact with dark matter, and 676 00:35:26,360 --> 00:35:28,239 Speaker 1: the dark matter doesn't care, but it will blow out 677 00:35:28,239 --> 00:35:31,160 Speaker 1: all the other star stuff that's in that Meni galaxy. 678 00:35:31,320 --> 00:35:34,080 Speaker 1: And that's why if you're small, then you'll most likely 679 00:35:34,120 --> 00:35:37,000 Speaker 1: blow out all of your star stuff, but you'll keep 680 00:35:37,040 --> 00:35:40,480 Speaker 1: your dark matter stuff. So it's like you're super concentrating 681 00:35:40,520 --> 00:35:45,680 Speaker 1: the dark matter, you're purifying, distilling it. There you go, yeah, distilling. 682 00:35:45,840 --> 00:35:48,279 Speaker 1: So the dwarf galaxies that are still around. They're the 683 00:35:48,320 --> 00:35:51,760 Speaker 1: ones with overwhelmingly dark matter and very very few stars 684 00:35:51,760 --> 00:35:54,600 Speaker 1: in them. They had like one initial round of star 685 00:35:54,680 --> 00:35:57,439 Speaker 1: formation and then they basically poison the well. So they're 686 00:35:57,480 --> 00:35:59,879 Speaker 1: also super fascinating from that point of view because they're 687 00:35:59,880 --> 00:36:03,200 Speaker 1: like fossils of star formation. They didn't have like many 688 00:36:03,239 --> 00:36:05,919 Speaker 1: many cycles like that, sort of like a window into 689 00:36:05,920 --> 00:36:09,400 Speaker 1: the much earlier part of the universe. But also they 690 00:36:09,440 --> 00:36:12,480 Speaker 1: are these very cool blobs of dark matter. And you know, 691 00:36:12,760 --> 00:36:16,400 Speaker 1: dark matter a continuing source of mystery and consternation for 692 00:36:16,520 --> 00:36:20,120 Speaker 1: a physicists, and these are really awesome laboratories to study 693 00:36:20,200 --> 00:36:22,960 Speaker 1: dark matter. But I guess you can't really see this 694 00:36:23,080 --> 00:36:25,759 Speaker 1: dark matter, right, you're just inferring that it's there, or 695 00:36:25,760 --> 00:36:29,520 Speaker 1: that this clump of stars has ninety nine point whatever 696 00:36:29,800 --> 00:36:32,319 Speaker 1: amount of dark matter. You're just seeing a little bit 697 00:36:32,360 --> 00:36:35,319 Speaker 1: of stars that are clumped together and spending more than 698 00:36:35,360 --> 00:36:37,759 Speaker 1: they should, and so you're inferring that there's a bunch 699 00:36:37,800 --> 00:36:40,040 Speaker 1: of dark matter there. Yeah, we're not seeing this dark 700 00:36:40,080 --> 00:36:43,640 Speaker 1: matter like directly using gravitational lensing for example. I mean 701 00:36:43,960 --> 00:36:46,640 Speaker 1: a few cases we can, but mostly we're inferring that 702 00:36:46,680 --> 00:36:48,960 Speaker 1: these clumps of stars have a lot of dark matter. 703 00:36:49,239 --> 00:36:52,480 Speaker 1: Based on the motion of the stars, which is originally 704 00:36:52,480 --> 00:36:55,600 Speaker 1: how we discover dark matter. We saw that stars are 705 00:36:55,680 --> 00:36:58,680 Speaker 1: moving really really fast, but that there's not enough stuff 706 00:36:58,719 --> 00:37:01,160 Speaker 1: in the galaxy to hold them together if they're moving 707 00:37:01,239 --> 00:37:03,239 Speaker 1: that fast, and which you can do if you look 708 00:37:03,280 --> 00:37:06,240 Speaker 1: at the velocity of stars, how fast they're moving around 709 00:37:06,239 --> 00:37:08,600 Speaker 1: the center of a galaxy is you can tell how 710 00:37:08,680 --> 00:37:11,040 Speaker 1: much gravity does there have to be to keep that 711 00:37:11,160 --> 00:37:13,719 Speaker 1: star at that distance from the center of that galaxy. 712 00:37:14,040 --> 00:37:16,480 Speaker 1: And that gives you like a map of the gravity 713 00:37:16,560 --> 00:37:19,399 Speaker 1: of that galaxy, which you can turn into a map 714 00:37:19,440 --> 00:37:21,439 Speaker 1: of the mass of the galaxy. And so you can say, 715 00:37:21,760 --> 00:37:24,560 Speaker 1: based on the spinning stars that I see, where is 716 00:37:24,640 --> 00:37:27,200 Speaker 1: the mass in that galaxy? And that tells you where 717 00:37:27,200 --> 00:37:29,520 Speaker 1: the dark matter is in that galaxy. So like a 718 00:37:29,600 --> 00:37:33,680 Speaker 1: few tracers in a galaxy will tell you basically where 719 00:37:33,719 --> 00:37:38,439 Speaker 1: the invisible mass is. What about our milkway, like what's 720 00:37:38,440 --> 00:37:41,680 Speaker 1: our percentage of dark matter to regular stars? So the 721 00:37:41,680 --> 00:37:44,480 Speaker 1: Milky way is a little bit more dark matter than 722 00:37:44,520 --> 00:37:47,719 Speaker 1: the rest of the universe. We're like ninety percent dark 723 00:37:47,760 --> 00:37:50,840 Speaker 1: matter and ten percent other stuff, whereas the rest of 724 00:37:50,840 --> 00:37:53,680 Speaker 1: the universe is about eighty percent dark matter. But it 725 00:37:53,800 --> 00:37:57,360 Speaker 1: also varies with distance from the center of the galaxy. 726 00:37:57,640 --> 00:37:59,799 Speaker 1: Like where we are where the Sun is relative to 727 00:38:00,080 --> 00:38:02,640 Speaker 1: enter the galaxy. Everything between us and the center is 728 00:38:02,680 --> 00:38:05,879 Speaker 1: about fifty fifty dark matter and other kinds of matter, 729 00:38:05,960 --> 00:38:07,960 Speaker 1: whereas if you go further out then it starts to 730 00:38:08,000 --> 00:38:11,320 Speaker 1: be overwhelmingly dark matter. And remember that the dark matter 731 00:38:11,400 --> 00:38:13,880 Speaker 1: halo for the Milky Way is much bigger than the 732 00:38:13,880 --> 00:38:17,080 Speaker 1: distribution of stars that goes out much much further, so 733 00:38:17,120 --> 00:38:19,320 Speaker 1: the stars peter arout and at some point it's only 734 00:38:19,400 --> 00:38:22,799 Speaker 1: dark matter. I guess anytime you're in between stars, you're 735 00:38:22,800 --> 00:38:25,399 Speaker 1: basically sitting in dark matter, right, Yeah, Well, we don't 736 00:38:25,440 --> 00:38:28,600 Speaker 1: really know the sort of fine scale structure of dark matter. 737 00:38:28,719 --> 00:38:31,360 Speaker 1: We have these very coarse probes from like how stars move, 738 00:38:31,840 --> 00:38:34,320 Speaker 1: and we have stellar streams. Were actually the whole podcast 739 00:38:34,320 --> 00:38:37,200 Speaker 1: episode about like trying to see the fine scale structure 740 00:38:37,200 --> 00:38:39,799 Speaker 1: of dark matter within the galaxy. It's really hard, and 741 00:38:39,840 --> 00:38:42,560 Speaker 1: the bottom line reason is that gravity is just super weak, 742 00:38:42,600 --> 00:38:44,279 Speaker 1: and so in order to measure where the dark matter is, 743 00:38:44,440 --> 00:38:46,840 Speaker 1: you need really big blobs of it, which means we 744 00:38:46,880 --> 00:38:49,600 Speaker 1: can't see small blobs of it. But we can look 745 00:38:49,640 --> 00:38:52,439 Speaker 1: at these dwarf galaxies and trace the motion of their 746 00:38:52,480 --> 00:38:55,160 Speaker 1: stars and use that to figure out where the dark 747 00:38:55,200 --> 00:38:58,120 Speaker 1: matter is in those galaxies and how much of it 748 00:38:58,160 --> 00:39:01,240 Speaker 1: there is. Well, it's interesting that our Milky Way galaxy 749 00:39:01,400 --> 00:39:04,720 Speaker 1: has kind of like a higher concentration of dark matter 750 00:39:04,760 --> 00:39:08,040 Speaker 1: than the rest of the other the universe in general 751 00:39:08,120 --> 00:39:10,720 Speaker 1: and other other galaxies as well. Are we a higher 752 00:39:10,719 --> 00:39:13,520 Speaker 1: concentration of dark matter than like Andromeda. We do have 753 00:39:13,600 --> 00:39:16,000 Speaker 1: board dark matter on average and Andromeda. Andromeda is a 754 00:39:16,000 --> 00:39:19,239 Speaker 1: bigger galaxy, and so it's a smaller chance to like 755 00:39:19,320 --> 00:39:23,040 Speaker 1: fluctuate up to have more dark matter than a smaller 756 00:39:23,040 --> 00:39:25,920 Speaker 1: galaxy like the Milky Way. But these smaller galaxies, like 757 00:39:25,920 --> 00:39:28,839 Speaker 1: the dwarf ones, they're really fun ways to study dark 758 00:39:28,880 --> 00:39:31,400 Speaker 1: matter because what one thing we can do, for example, 759 00:39:31,520 --> 00:39:33,680 Speaker 1: is we can look to see whether the dark matter 760 00:39:33,800 --> 00:39:37,840 Speaker 1: in these dwarf galaxies is banging into itself and giving 761 00:39:37,880 --> 00:39:41,960 Speaker 1: off some sort of like telltale signature. Particle physicists particular 762 00:39:42,000 --> 00:39:45,279 Speaker 1: of like pointing their telescopes at these dwarf galaxies to 763 00:39:45,400 --> 00:39:48,440 Speaker 1: try to see signals from the dark matter. Oh, I 764 00:39:48,440 --> 00:39:51,520 Speaker 1: see what you're saying. Like we can use dwarf galaxies 765 00:39:51,960 --> 00:39:54,520 Speaker 1: as kind of like a way to know where there's 766 00:39:54,560 --> 00:39:56,760 Speaker 1: a lot of dark matter out there in the emptiness 767 00:39:56,800 --> 00:39:58,799 Speaker 1: of space. Like if you see a dwarf galaxy, then 768 00:39:58,880 --> 00:40:01,840 Speaker 1: that gives you a target. Point your telescope too, and say, okay, 769 00:40:01,840 --> 00:40:04,200 Speaker 1: I know for sure there's a lot of dark matter 770 00:40:04,280 --> 00:40:07,680 Speaker 1: in this one spot. It's the dark matter doing anything 771 00:40:07,800 --> 00:40:10,000 Speaker 1: interesting that might tell us a little bit about what 772 00:40:10,080 --> 00:40:13,520 Speaker 1: it is exactly. And one particularly interesting thing that people 773 00:40:13,640 --> 00:40:17,360 Speaker 1: hope dark matter will do is that two dark matter particles, 774 00:40:17,440 --> 00:40:19,759 Speaker 1: whatever they are, we don't know what they are, might 775 00:40:19,840 --> 00:40:22,879 Speaker 1: smash into each other and they might annihilate, might turn 776 00:40:22,960 --> 00:40:27,759 Speaker 1: into something else, and occasionally that will involve turning into photons. 777 00:40:28,080 --> 00:40:30,600 Speaker 1: So normally we think of dark matter as dark not 778 00:40:30,840 --> 00:40:33,600 Speaker 1: creating any photons, but there are some theories where it 779 00:40:33,640 --> 00:40:37,560 Speaker 1: has some kind of interaction which eventually can turn into photons. 780 00:40:37,600 --> 00:40:40,839 Speaker 1: And so you see this like characteristic flash of gamma rays. 781 00:40:41,360 --> 00:40:44,160 Speaker 1: Problem is the universe filled with gamma rays. All sorts 782 00:40:44,200 --> 00:40:46,600 Speaker 1: of other stuff generates gamma raise. So one thing you 783 00:40:46,600 --> 00:40:48,440 Speaker 1: can do is point your telescope at the center of 784 00:40:48,440 --> 00:40:50,160 Speaker 1: the galaxy where you expect there to be a lot 785 00:40:50,200 --> 00:40:52,640 Speaker 1: of dark matter and look for gamma raise. But you 786 00:40:52,760 --> 00:40:56,799 Speaker 1: like swamped in gamma rays from other stuff. Dwarf galaxies 787 00:40:56,880 --> 00:41:00,200 Speaker 1: have very little other stuff. They're mostly dark matter. So 788 00:41:00,239 --> 00:41:02,120 Speaker 1: if you point your telescope at the heart of these 789 00:41:02,440 --> 00:41:05,600 Speaker 1: dark matter galaxies, these dwarf galaxies, and you see gamma 790 00:41:05,680 --> 00:41:08,360 Speaker 1: rays there, then you can be more certain that it 791 00:41:08,400 --> 00:41:11,399 Speaker 1: comes from dark matter. We haven't seen any there's nothing 792 00:41:11,480 --> 00:41:14,680 Speaker 1: unusual emanating from the hearts of these dwarf galaxies. But 793 00:41:14,719 --> 00:41:17,440 Speaker 1: they've given us some really powerful limits telling us what 794 00:41:17,520 --> 00:41:19,879 Speaker 1: dark matter doesn't do. Wait, are you saying that dark 795 00:41:19,920 --> 00:41:23,839 Speaker 1: matter it might be actually shining and might a mid light? 796 00:41:24,640 --> 00:41:26,640 Speaker 1: Would you have to change the name then, from dark 797 00:41:26,640 --> 00:41:31,440 Speaker 1: matter to like dim matter darkish matter. There's so many 798 00:41:31,520 --> 00:41:33,840 Speaker 1: theories of dark matter that you can't even really describe 799 00:41:33,840 --> 00:41:35,840 Speaker 1: all of them, and so many ways to look for 800 00:41:35,960 --> 00:41:38,400 Speaker 1: dark matter. You know, people complain to me sometimes like 801 00:41:38,480 --> 00:41:40,160 Speaker 1: you guys are still looking for dark matter. You haven' 802 00:41:40,160 --> 00:41:41,440 Speaker 1: found it? When are you going to give up? The 803 00:41:41,480 --> 00:41:43,440 Speaker 1: problem is that there's so many ways that dark matter 804 00:41:43,520 --> 00:41:45,920 Speaker 1: could be discovered, and so many different ideas for what 805 00:41:45,960 --> 00:41:48,400 Speaker 1: it could look like Because we know so little about 806 00:41:48,400 --> 00:41:50,360 Speaker 1: it that we've got to try lots of different ways, 807 00:41:50,360 --> 00:41:52,880 Speaker 1: and in some of those theories, Yeah, dark matter can 808 00:41:52,920 --> 00:41:56,239 Speaker 1: annihilate and turn into photons. So yeah, what is still 809 00:41:56,280 --> 00:41:58,319 Speaker 1: be called dark matter? I look forward to having that 810 00:41:58,400 --> 00:42:00,640 Speaker 1: argument with you when we collect our Will Prize for 811 00:42:00,719 --> 00:42:03,799 Speaker 1: discovering dark matter. Well, if dark matter doesn't midlight, it's 812 00:42:03,800 --> 00:42:06,600 Speaker 1: gonna be kind of dim and it's gonna be a 813 00:42:06,760 --> 00:42:08,840 Speaker 1: dark ish and it's gonna be sort of red shifted, 814 00:42:08,880 --> 00:42:11,359 Speaker 1: right because these galaxies are probably moving away from us, 815 00:42:11,360 --> 00:42:16,640 Speaker 1: which means that you could technically call it chocolate. And 816 00:42:16,680 --> 00:42:19,200 Speaker 1: if it's red shifted, it should be like rose chocolate matter, right, 817 00:42:19,640 --> 00:42:22,520 Speaker 1: Is that a thing? Is rose chocolate a thing? Yeah? Absolutely, 818 00:42:22,560 --> 00:42:25,680 Speaker 1: they invented it recently. He had dark chocolate, milk chocolate, 819 00:42:25,719 --> 00:42:28,760 Speaker 1: white chocolate, and now rose chocolate. It's a whole new process. 820 00:42:29,000 --> 00:42:33,000 Speaker 1: M Well, there you go. Physicists are inventing new things 821 00:42:33,000 --> 00:42:36,080 Speaker 1: all the time. That was definitely not a physics invention. 822 00:42:36,120 --> 00:42:38,000 Speaker 1: I think it was Nestlie that came out with it. 823 00:42:38,120 --> 00:42:40,279 Speaker 1: But we can do more than just look for dark 824 00:42:40,280 --> 00:42:43,440 Speaker 1: matter annihilating with itself. We can also study in detail 825 00:42:43,520 --> 00:42:46,240 Speaker 1: the distribution of dark matter, like where in these dwarf 826 00:42:46,239 --> 00:42:49,400 Speaker 1: galaxies did did dark matter end up? And does it 827 00:42:49,520 --> 00:42:53,560 Speaker 1: agree with our simulations and our calculations because we can 828 00:42:53,560 --> 00:42:55,880 Speaker 1: tell not just how much dark matter there is, but 829 00:42:55,960 --> 00:42:58,080 Speaker 1: also like is it mostly at the core, is it 830 00:42:58,160 --> 00:43:01,640 Speaker 1: really clumped, is it smooth spread out? This kind of stuff, 831 00:43:01,880 --> 00:43:04,080 Speaker 1: and what we see is that it does not agree 832 00:43:04,400 --> 00:43:07,320 Speaker 1: with what we predict. That our simulations get it wrong. 833 00:43:07,760 --> 00:43:10,120 Speaker 1: How can we tell how it's distributed. If it's invisible, 834 00:43:10,320 --> 00:43:12,960 Speaker 1: it's invisible, but it affects the motion of the stars. 835 00:43:13,400 --> 00:43:15,480 Speaker 1: And so if, for example, you have all the dark 836 00:43:15,480 --> 00:43:18,280 Speaker 1: matter at the very very center, then the stars closer 837 00:43:18,280 --> 00:43:20,480 Speaker 1: to the center will be going really really fast. If 838 00:43:20,480 --> 00:43:22,880 Speaker 1: the dark matter is more spread out, then the stars 839 00:43:22,920 --> 00:43:24,920 Speaker 1: closer to the center are not as affected by all 840 00:43:24,920 --> 00:43:27,200 Speaker 1: that dark matter. So by looking at how the velocity 841 00:43:27,239 --> 00:43:29,960 Speaker 1: of the stars changes as you get further from the center, 842 00:43:30,239 --> 00:43:32,880 Speaker 1: we can make a map of where in the galaxy 843 00:43:33,280 --> 00:43:35,480 Speaker 1: that dark matter is. Is it all clumped in the center, 844 00:43:35,560 --> 00:43:38,279 Speaker 1: is it more spread out? And when we do that 845 00:43:38,400 --> 00:43:41,359 Speaker 1: we see weird stuff that we don't understand. What I mean, 846 00:43:41,440 --> 00:43:44,000 Speaker 1: weird stuff. So our simulations predict that you should have 847 00:43:44,040 --> 00:43:46,520 Speaker 1: like a really hard core of dark matter, that yeah, 848 00:43:46,560 --> 00:43:48,759 Speaker 1: you have a big fluffy halo, but the density should 849 00:43:48,840 --> 00:43:51,520 Speaker 1: rise really rapidly as you get towards the center, and 850 00:43:51,600 --> 00:43:53,960 Speaker 1: what we see in our telescopes is not the same thing. 851 00:43:54,000 --> 00:43:56,640 Speaker 1: We see like a flatter distribution. It doesn't get as 852 00:43:56,719 --> 00:43:59,560 Speaker 1: peaky towards the core. The density of dark matter at 853 00:43:59,600 --> 00:44:02,719 Speaker 1: the very part of these dwarf galaxies is lower than 854 00:44:02,760 --> 00:44:05,120 Speaker 1: what we expect in astronomy. This is called as the 855 00:44:05,200 --> 00:44:09,120 Speaker 1: core versus cusp problem. Simulations predict a sharp cusp in 856 00:44:09,160 --> 00:44:11,279 Speaker 1: the density, but what we see is more like a 857 00:44:11,320 --> 00:44:14,719 Speaker 1: flat core. They're fuzzier than you expected. But isn't that 858 00:44:14,760 --> 00:44:17,239 Speaker 1: just kind of a matter of time, Like, over time 859 00:44:17,440 --> 00:44:20,040 Speaker 1: it should clump together towards the center, right, because that's 860 00:44:20,080 --> 00:44:22,640 Speaker 1: what dark matter does. It is, and we factor that 861 00:44:22,680 --> 00:44:25,719 Speaker 1: time into our simulations, and the predictions just disagree with 862 00:44:25,760 --> 00:44:28,839 Speaker 1: what we expect to see at a universe of this age. Yeah, 863 00:44:28,840 --> 00:44:31,000 Speaker 1: so yeah, over time it will tend to clump more 864 00:44:31,040 --> 00:44:33,319 Speaker 1: and more and more. But it hasn't clumped as much 865 00:44:33,360 --> 00:44:36,600 Speaker 1: as we expected. What could it be? What could be 866 00:44:36,640 --> 00:44:39,200 Speaker 1: the explanation? Well, there's lots of really fun ideas. This 867 00:44:39,280 --> 00:44:41,080 Speaker 1: is a big crack and sort of the success of 868 00:44:41,200 --> 00:44:43,720 Speaker 1: dark matter and explaining the large structure of the universe. 869 00:44:43,800 --> 00:44:46,120 Speaker 1: And some people think it's a good argument for Mond 870 00:44:46,520 --> 00:44:48,919 Speaker 1: one of these alternative theories. It says, you know, dark 871 00:44:48,960 --> 00:44:51,600 Speaker 1: matter doesn't even exist at all. It's just that we've 872 00:44:51,600 --> 00:44:55,160 Speaker 1: misunderstood gravity, and the gravity at different distance scales and 873 00:44:55,160 --> 00:44:58,880 Speaker 1: the different accelerations works differently than we expected, and the 874 00:44:58,920 --> 00:45:01,279 Speaker 1: whole dark matter thing is mistake. And it's true that 875 00:45:01,400 --> 00:45:03,719 Speaker 1: dark matter does not do a good job of explaining 876 00:45:03,800 --> 00:45:05,920 Speaker 1: what we see in these dwarf galaxies. It's like a 877 00:45:05,960 --> 00:45:08,960 Speaker 1: big open problem for dark matter, and Mond does a 878 00:45:09,000 --> 00:45:11,879 Speaker 1: good job of explaining what we see in these galaxies, 879 00:45:12,000 --> 00:45:14,120 Speaker 1: and so that's a bit of a puzzle, right. Mind 880 00:45:14,200 --> 00:45:16,760 Speaker 1: also fails to explain lots of other stuff in the universe, 881 00:45:16,800 --> 00:45:19,520 Speaker 1: lots of reasons why we think dark matter is a 882 00:45:19,560 --> 00:45:23,200 Speaker 1: better sort of overall picture than MOND, But this is 883 00:45:23,239 --> 00:45:26,279 Speaker 1: one place where Mond does better than dark matter. What 884 00:45:26,360 --> 00:45:28,720 Speaker 1: are some of these ideas then that maybe dark matter 885 00:45:28,800 --> 00:45:32,000 Speaker 1: does have some strange interaction with itself, or maybe there's 886 00:45:32,000 --> 00:45:34,560 Speaker 1: like a dark matter sun in the middle of that 887 00:45:34,640 --> 00:45:38,359 Speaker 1: galaxy blowing out some of the dark matter stuff like that. Yeah, 888 00:45:38,440 --> 00:45:40,839 Speaker 1: one really interesting clue is that there's actually a lot 889 00:45:40,840 --> 00:45:43,799 Speaker 1: of variation, Like they're not as cuspies you expect. But 890 00:45:44,080 --> 00:45:47,000 Speaker 1: also these cores is a lot of diversity of these cores, 891 00:45:47,280 --> 00:45:49,640 Speaker 1: so you see lots of different sort of shapes, and 892 00:45:49,680 --> 00:45:51,600 Speaker 1: people wonder like, why would you get so many different 893 00:45:51,600 --> 00:45:53,800 Speaker 1: shape if the only thing that's happening here is gravity. 894 00:45:53,840 --> 00:45:56,520 Speaker 1: Gravity is pretty simple. It's not as complicated as like 895 00:45:56,600 --> 00:46:00,400 Speaker 1: baryonic physics, you know, with photons and protons and electromaticism. 896 00:46:00,440 --> 00:46:04,759 Speaker 1: It's very complicated. Dark matter should create simpler structures. And 897 00:46:04,840 --> 00:46:07,200 Speaker 1: so one idea is just what you suggested, that maybe 898 00:46:07,280 --> 00:46:10,200 Speaker 1: dark matter has some complicated self interaction that we don't 899 00:46:10,239 --> 00:46:13,719 Speaker 1: know about that's creating interesting sorts of structures in the 900 00:46:13,760 --> 00:46:16,520 Speaker 1: hearts of these galaxies that we just can't see because 901 00:46:16,560 --> 00:46:18,960 Speaker 1: it's all made out of dark matter. So it's sort 902 00:46:19,000 --> 00:46:21,080 Speaker 1: of like the cutting edge of current research is to 903 00:46:21,120 --> 00:46:23,440 Speaker 1: try to understand what's going on at the hearts of 904 00:46:23,480 --> 00:46:27,399 Speaker 1: these dwarf galaxies. What is dark matter doing right? Right? 905 00:46:27,440 --> 00:46:31,480 Speaker 1: It could be boring like rose chocolate bars for all 906 00:46:31,520 --> 00:46:34,960 Speaker 1: you know, right, huge cups of rose chocolate cosmic hot 907 00:46:34,960 --> 00:46:37,000 Speaker 1: coco could just be out there waiting for us to 908 00:46:37,000 --> 00:46:39,240 Speaker 1: sip them. But then if you're out there sipping them, 909 00:46:39,760 --> 00:46:41,960 Speaker 1: you're also looking at the stars, but you're inside of 910 00:46:41,960 --> 00:46:43,719 Speaker 1: the stars. Kind oh, my gosh, I don't even know 911 00:46:43,719 --> 00:46:44,960 Speaker 1: what to do. I'd have to be camping at the 912 00:46:45,000 --> 00:46:49,840 Speaker 1: same time. Yeah, camping in space, space camping. That's absolutely 913 00:46:49,840 --> 00:46:52,080 Speaker 1: the title of my new science fiction TV series that 914 00:46:52,120 --> 00:46:54,600 Speaker 1: I'm pitching to Netflix. There you go. Well, I think 915 00:46:54,640 --> 00:46:58,879 Speaker 1: they already have space camp but maybe you can get 916 00:46:58,880 --> 00:47:04,319 Speaker 1: away with trademarking. This is why we have lawyers. They'll 917 00:47:04,320 --> 00:47:07,640 Speaker 1: figure it out. Yeah, they'll figure it out, all right. Well, 918 00:47:07,680 --> 00:47:10,960 Speaker 1: another interesting journey into a corner of the universe that 919 00:47:11,080 --> 00:47:13,040 Speaker 1: maybe a lot of people don't pay attention to, but 920 00:47:13,080 --> 00:47:15,799 Speaker 1: that could actually reveal a lot about how things work. 921 00:47:16,080 --> 00:47:19,239 Speaker 1: Dwarf galaxies. And remember that as we develop better and 922 00:47:19,360 --> 00:47:22,800 Speaker 1: more powerful technological eyeballs to look out into the universe, 923 00:47:22,880 --> 00:47:26,319 Speaker 1: we see fainter stuff and smaller stuff, which might hold 924 00:47:26,560 --> 00:47:29,279 Speaker 1: some of the answers to some of the enduring mysteries 925 00:47:29,320 --> 00:47:31,800 Speaker 1: we've been puzzling over for a long time. So the 926 00:47:31,880 --> 00:47:35,040 Speaker 1: next time you're out there camping or not, or looking 927 00:47:35,040 --> 00:47:38,120 Speaker 1: at the stars or not, or drinking hot chocolate or not, 928 00:47:39,000 --> 00:47:42,480 Speaker 1: you can do those three things independently. Think about the 929 00:47:42,520 --> 00:47:44,799 Speaker 1: little structures of the universe out there and how they 930 00:47:44,880 --> 00:47:47,960 Speaker 1: maybe have special properties that can really kind of reveal 931 00:47:48,080 --> 00:47:51,560 Speaker 1: some of the more interesting inner workings of the universe. 932 00:47:51,640 --> 00:47:53,439 Speaker 1: I have one last question for you before we sign 933 00:47:53,480 --> 00:47:54,919 Speaker 1: off for him. Do you prefer a cup of hot 934 00:47:54,920 --> 00:47:58,040 Speaker 1: cocoa or hot vanilla? Hot vanilla? You mean like pure 935 00:47:58,120 --> 00:48:00,440 Speaker 1: vanilla extract? I don't know. You said nila is your 936 00:48:00,440 --> 00:48:03,480 Speaker 1: favorite flavor, better than chocolate. So what's a delicious vanilla 937 00:48:03,520 --> 00:48:06,839 Speaker 1: beverage you enjoy on a camping trip? Oh? Boy, yeah, 938 00:48:07,080 --> 00:48:12,720 Speaker 1: just warm milk. I think it's just called warm milk. 939 00:48:13,120 --> 00:48:17,239 Speaker 1: Somebody invented that too, man. Yeah, yeah, vanilla milkshake. I'll 940 00:48:17,280 --> 00:48:19,439 Speaker 1: take that camping any day. All right. Well, we hope 941 00:48:19,440 --> 00:48:22,960 Speaker 1: you enjoyed that. Thanks for joining us, See you next time. 942 00:48:30,840 --> 00:48:33,640 Speaker 1: Thanks for listening, and remember that Daniel and Jorge explain 943 00:48:33,719 --> 00:48:37,600 Speaker 1: the Universe is a production of iHeartRadio. Or more podcast 944 00:48:37,760 --> 00:48:41,680 Speaker 1: from my heart Radio. Visit the iHeartRadio app, Apple Podcasts, 945 00:48:41,800 --> 00:48:44,160 Speaker 1: or wherever you listen to your favorite shows.