1
00:00:08,600 --> 00:00:10,480
Speaker 1: Hey, or hey, does the town you live in have

2
00:00:10,680 --> 00:00:12,800
Speaker 1: a real center, like a downtown.

3
00:00:13,520 --> 00:00:15,800
Speaker 2: It does, Yeah, it has a little kind of town

4
00:00:15,840 --> 00:00:18,960
Speaker 2: square where everyone hangs out. There's also downtown LA which

5
00:00:19,000 --> 00:00:20,119
Speaker 2: is about ten minutes away.

6
00:00:20,160 --> 00:00:22,880
Speaker 1: And does anybody ever go to downtown La? Is it

7
00:00:22,920 --> 00:00:23,759
Speaker 1: like a destination?

8
00:00:24,079 --> 00:00:26,600
Speaker 2: Kind of? Sometimes we just went to like a science

9
00:00:26,720 --> 00:00:29,320
Speaker 2: festival there, but not typically it's pretty rare.

10
00:00:29,640 --> 00:00:33,800
Speaker 1: I guess it's also like the center of traffic in LA. Yeah.

11
00:00:34,440 --> 00:00:38,279
Speaker 1: What about Irvine? Irvine has no center. It's just one

12
00:00:38,400 --> 00:00:40,360
Speaker 1: hundred percent pure sprawl.

13
00:00:40,800 --> 00:00:42,040
Speaker 2: It's all edges, it's.

14
00:00:41,920 --> 00:00:43,760
Speaker 1: All parking lots and shopping centers.

15
00:00:43,840 --> 00:00:45,120
Speaker 2: So if you find yourself in the middle of a

16
00:00:45,159 --> 00:00:47,520
Speaker 2: parking lot all of a sudden, you might be totally lost.

17
00:00:48,320 --> 00:00:51,200
Speaker 1: It's actually the law in Irvine that everything is legally

18
00:00:51,240 --> 00:00:55,200
Speaker 1: required to be exactly identically bland, even the people. We're

19
00:00:55,240 --> 00:00:57,680
Speaker 1: all beige down here because of the sunshine in.

20
00:00:57,600 --> 00:01:09,240
Speaker 3: More ways than one.

21
00:01:13,800 --> 00:01:17,240
Speaker 2: Hi. I'm Poorgammy, cartoonist and the creator of PhD comics. Hi,

22
00:01:17,319 --> 00:01:17,880
Speaker 2: I'm Daniel.

23
00:01:17,959 --> 00:01:20,920
Speaker 1: I'm a particle physicist and a professor. You see Irvine,

24
00:01:21,200 --> 00:01:24,640
Speaker 1: and I've learned to distinguish fifty shades of beige.

25
00:01:24,680 --> 00:01:28,199
Speaker 2: Sounds like a fan fiction version of fifty Shades of Gray,

26
00:01:28,800 --> 00:01:30,240
Speaker 2: but less seamy.

27
00:01:31,440 --> 00:01:34,280
Speaker 1: Totally safe for work. When we moved into our house

28
00:01:34,319 --> 00:01:37,160
Speaker 1: in Irvine, real story, they gave us a set of

29
00:01:37,200 --> 00:01:39,920
Speaker 1: options of the colors, and at the topa said color

30
00:01:39,959 --> 00:01:42,360
Speaker 1: makes a world of difference, and then there were four

31
00:01:42,440 --> 00:01:44,240
Speaker 1: shades of beige you could choose from.

32
00:01:44,480 --> 00:01:47,000
Speaker 2: Wow, that's a lot of options of beige. So you

33
00:01:47,040 --> 00:01:48,880
Speaker 2: can't paint your house green if you wanted to.

34
00:01:49,280 --> 00:01:52,600
Speaker 1: No, we are restricted from painting our house various colors.

35
00:01:52,600 --> 00:01:56,040
Speaker 1: We actually once did paint our garage crazy rainbow stripes,

36
00:01:56,240 --> 00:01:57,720
Speaker 1: and we've got a stern letter M.

37
00:01:58,240 --> 00:01:59,600
Speaker 2: And what happens if you don't change it.

38
00:02:00,000 --> 00:02:01,920
Speaker 1: They repaint it for you, and then they send you

39
00:02:01,960 --> 00:02:02,520
Speaker 1: the bill.

40
00:02:03,440 --> 00:02:06,040
Speaker 2: The city will send them a painter to your house.

41
00:02:06,440 --> 00:02:08,040
Speaker 2: Sounds very nineteen eighty fourge.

42
00:02:08,200 --> 00:02:10,480
Speaker 1: That's why all the exciting stuff that's happening in Irvine

43
00:02:10,560 --> 00:02:12,520
Speaker 1: is happening inside people's houses.

44
00:02:12,760 --> 00:02:17,079
Speaker 2: Oh, fifty shades of hidden page. But anyways, Welcome to

45
00:02:17,120 --> 00:02:20,000
Speaker 2: our podcast Daniel and Jorge Explain the Universe, a production

46
00:02:20,080 --> 00:02:21,720
Speaker 2: of iHeartRadio.

47
00:02:21,000 --> 00:02:24,120
Speaker 1: In which we try to illuminate all the amazing shades

48
00:02:24,160 --> 00:02:27,960
Speaker 1: of meaning and nuance in the universe. We go all

49
00:02:27,960 --> 00:02:31,440
Speaker 1: the way from black holes to white dwarfs and everything

50
00:02:31,560 --> 00:02:35,600
Speaker 1: in between. The incredible color and ferocity of the processes

51
00:02:35,639 --> 00:02:38,440
Speaker 1: in the universe, the intensity in the screaming jets, from

52
00:02:38,480 --> 00:02:42,120
Speaker 1: the centers of galaxies to the very quiet outer edges

53
00:02:42,400 --> 00:02:45,040
Speaker 1: of stellar clusters. We talk about all of it. We

54
00:02:45,160 --> 00:02:47,679
Speaker 1: dig into every little bit of it. We touch on

55
00:02:47,840 --> 00:02:51,200
Speaker 1: our curiosity to understand the universe around us, and we

56
00:02:51,280 --> 00:02:52,360
Speaker 1: explain all of it to you.

57
00:02:52,600 --> 00:02:55,440
Speaker 2: That's right, because it is a pretty colorful universe, and

58
00:02:55,480 --> 00:02:58,160
Speaker 2: we try to paint the whole rainbow of knowledge that

59
00:02:58,240 --> 00:03:01,360
Speaker 2: humans have managed to figure out over Leniam about this

60
00:03:01,639 --> 00:03:05,079
Speaker 2: amazing universe that we live in, which is not all

61
00:03:05,120 --> 00:03:08,320
Speaker 2: concentrated in one place, but it's also not all evenly

62
00:03:08,360 --> 00:03:09,880
Speaker 2: distributed across the universe.

63
00:03:10,000 --> 00:03:12,160
Speaker 1: Yeah, that's right. And we look at the world around

64
00:03:12,280 --> 00:03:15,520
Speaker 1: us in all sorts of crazy colors, reds and greens

65
00:03:15,520 --> 00:03:16,120
Speaker 1: and blues.

66
00:03:16,480 --> 00:03:17,320
Speaker 2: But when we look.

67
00:03:17,200 --> 00:03:20,320
Speaker 1: Out into the wider universe, we can use other frequencies

68
00:03:20,320 --> 00:03:23,400
Speaker 1: of light, frequencies that don't even have color, all the

69
00:03:23,400 --> 00:03:26,400
Speaker 1: way down from the radio waves up to a gamma rays,

70
00:03:26,560 --> 00:03:29,040
Speaker 1: light that wiggles super duper fast, and light that wiggles

71
00:03:29,240 --> 00:03:30,280
Speaker 1: much much slower.

72
00:03:30,360 --> 00:03:33,400
Speaker 2: I just had this interesting conversation recently where I learned

73
00:03:33,400 --> 00:03:36,040
Speaker 2: that magenta is not really a color. Do you know

74
00:03:36,080 --> 00:03:40,800
Speaker 2: that it's just a word? What is magenta exactly? Not really? Well,

75
00:03:40,800 --> 00:03:43,520
Speaker 2: I guess it's not really a frequency of color. It's

76
00:03:43,520 --> 00:03:47,120
Speaker 2: like a color we see when you combine certain frequencies

77
00:03:47,400 --> 00:03:47,880
Speaker 2: in your head.

78
00:03:48,080 --> 00:03:50,600
Speaker 1: Oh, I see, there's no single frequency of light that

79
00:03:50,640 --> 00:03:53,600
Speaker 1: if you shoot it at an eyeballer person will experience magenta.

80
00:03:53,720 --> 00:03:56,440
Speaker 2: Yeah. Or I think related is color pink? Like, there's

81
00:03:56,480 --> 00:03:58,480
Speaker 2: no color pink. Isn't that true? Then for white?

82
00:03:58,560 --> 00:04:00,880
Speaker 1: Also, you can't have like a white light because white

83
00:04:00,920 --> 00:04:02,520
Speaker 1: is every frequency together. Mmm.

84
00:04:03,600 --> 00:04:06,520
Speaker 2: Interesting, Yeah, I guess white. Well, white was never a color.

85
00:04:06,920 --> 00:04:11,080
Speaker 2: What white is not a color? Wow?

86
00:04:11,160 --> 00:04:16,080
Speaker 1: This has quickly become a philosophy of color. Podcast Is

87
00:04:16,160 --> 00:04:17,280
Speaker 1: black not a color either?

88
00:04:17,480 --> 00:04:19,800
Speaker 2: Right? I don't know. Is it is the lack of

89
00:04:19,880 --> 00:04:21,520
Speaker 2: light of color? I don't know.

90
00:04:21,560 --> 00:04:24,480
Speaker 1: I think color is just something you experience in your mind. Anyway,

91
00:04:24,520 --> 00:04:26,240
Speaker 1: It's not a property of the photons.

92
00:04:26,440 --> 00:04:26,600
Speaker 2: Right.

93
00:04:26,680 --> 00:04:29,719
Speaker 1: Infrared photons and gamma ray photons don't have any color,

94
00:04:29,800 --> 00:04:33,159
Speaker 1: so either do photons that stimulate a green response in

95
00:04:33,200 --> 00:04:35,320
Speaker 1: your mind? The green is just in your head, man,

96
00:04:35,760 --> 00:04:38,440
Speaker 1: so is magenta, so is black, So as white. Color

97
00:04:38,560 --> 00:04:41,440
Speaker 1: is just an experience. So beige is also just in

98
00:04:41,440 --> 00:04:44,000
Speaker 1: your head. Nothing to complain about.

99
00:04:44,120 --> 00:04:48,760
Speaker 2: No, now you run the beige within me. Ah, that

100
00:04:49,279 --> 00:04:53,120
Speaker 2: is my fault. You are beige inside and out, Daniel,

101
00:04:53,520 --> 00:04:54,000
Speaker 2: Oh my.

102
00:04:54,040 --> 00:04:56,680
Speaker 1: God, all this time I thought I'd escape the bigeness.

103
00:04:56,760 --> 00:04:59,239
Speaker 2: But you're right, Irvine has gone into you. It's seeped

104
00:04:59,279 --> 00:05:03,640
Speaker 2: into your por and you're Europe. I'm beage through and through,

105
00:05:03,680 --> 00:05:05,920
Speaker 2: that's what you're saying. But anyways, and there are a

106
00:05:05,960 --> 00:05:08,120
Speaker 2: lot of colors out there in the universe, but it's

107
00:05:08,120 --> 00:05:10,240
Speaker 2: not all evenly disturbed. Like if you look out into

108
00:05:10,279 --> 00:05:12,440
Speaker 2: the night sky, you don't see it just all light.

109
00:05:12,640 --> 00:05:15,920
Speaker 2: There are patches of not light and patches of intense light.

110
00:05:16,160 --> 00:05:19,120
Speaker 1: Yeah, as we build these technological eyeballs that can see

111
00:05:19,160 --> 00:05:21,520
Speaker 1: photons of various colors when we look out and use

112
00:05:21,560 --> 00:05:23,520
Speaker 1: it to build a map of what's out there in

113
00:05:23,560 --> 00:05:26,880
Speaker 1: the universe. Where are all the other stars in the universe?

114
00:05:26,920 --> 00:05:29,760
Speaker 1: How do they cluster together? What's going on around the corner?

115
00:05:30,080 --> 00:05:32,279
Speaker 1: Are we in the boring part of the universe or

116
00:05:32,279 --> 00:05:34,040
Speaker 1: are we at the hopping city center?

117
00:05:34,240 --> 00:05:37,080
Speaker 2: Yeah, where are the happening places in the universe. So

118
00:05:37,160 --> 00:05:44,520
Speaker 2: today on the podcast, we'll be tackling the question what

119
00:05:44,720 --> 00:05:48,480
Speaker 2: does the center of the galaxy look like? And more important,

120
00:05:48,560 --> 00:05:51,040
Speaker 2: what does it smell like? And this is the thing

121
00:05:51,080 --> 00:05:52,240
Speaker 2: that smells in space.

122
00:05:52,440 --> 00:05:54,919
Speaker 1: There are smells in space, absolutely, because there's lots of

123
00:05:54,920 --> 00:05:58,320
Speaker 1: fascinating organic molecules out there. Remember that whole episode we

124
00:05:58,360 --> 00:06:01,400
Speaker 1: did about the smells of space astronauts coming in from

125
00:06:01,440 --> 00:06:04,640
Speaker 1: spacewalks and reporting that their suits smelled like barbecue.

126
00:06:05,000 --> 00:06:05,160
Speaker 4: Mm.

127
00:06:06,240 --> 00:06:09,159
Speaker 2: So you're saying it space malls like death. No, space

128
00:06:09,200 --> 00:06:13,880
Speaker 2: smells like lunch. Space smells like you're never going to

129
00:06:13,920 --> 00:06:16,200
Speaker 2: breathe again if you actually smell space.

130
00:06:16,320 --> 00:06:19,160
Speaker 1: Yeah, that's right. And it's interesting that the galaxy has

131
00:06:19,200 --> 00:06:21,839
Speaker 1: a center. You know, our solar system has the center,

132
00:06:21,920 --> 00:06:24,000
Speaker 1: the Earth has a center, the galaxy has a center.

133
00:06:24,480 --> 00:06:26,400
Speaker 1: But then on a broader scale, we don't think the

134
00:06:26,600 --> 00:06:30,000
Speaker 1: universe has a center. And it's interesting to me as

135
00:06:30,000 --> 00:06:32,160
Speaker 1: a sort of human reaction. It's the sort of our

136
00:06:32,240 --> 00:06:35,000
Speaker 1: way of categorizing stuff, So is that we look for

137
00:06:35,040 --> 00:06:37,800
Speaker 1: the center of things. Lots of listeners write in and

138
00:06:37,839 --> 00:06:40,279
Speaker 1: ask about where is the center of the universe, Like

139
00:06:40,320 --> 00:06:43,000
Speaker 1: it's an important thing to understand where the center of

140
00:06:43,040 --> 00:06:43,640
Speaker 1: something is.

141
00:06:44,080 --> 00:06:46,400
Speaker 2: Yeah, I guess it's sort of a way to orient

142
00:06:46,480 --> 00:06:49,400
Speaker 2: yourself and know where you are relative to other things.

143
00:06:49,440 --> 00:06:50,919
Speaker 2: Like if you know where the center of town is,

144
00:06:50,960 --> 00:06:53,480
Speaker 2: and you sort of know where you are. But if

145
00:06:53,520 --> 00:06:57,560
Speaker 2: it was a whole ingenious population of buildings, then it'd

146
00:06:57,560 --> 00:07:00,000
Speaker 2: be easy to get lost or feel lost at least.

147
00:07:00,200 --> 00:07:02,520
Speaker 1: Yeah, that's why I still get lost in an her behind.

148
00:07:02,640 --> 00:07:05,240
Speaker 1: I think because there is no way to orient yourself.

149
00:07:05,279 --> 00:07:07,560
Speaker 1: But I think also there's a sense of origin, right,

150
00:07:07,600 --> 00:07:10,080
Speaker 1: there's the feeling that like the most important things are

151
00:07:10,120 --> 00:07:13,120
Speaker 1: happening at the center, or the processes that drive the

152
00:07:13,160 --> 00:07:15,400
Speaker 1: formation of whatever it is you're talking about the Earth

153
00:07:15,520 --> 00:07:19,000
Speaker 1: or the Solar system or the galaxy are determined by

154
00:07:19,040 --> 00:07:21,680
Speaker 1: the stuff happening at the center. It's not usually the

155
00:07:21,680 --> 00:07:24,440
Speaker 1: case that the outer edges are controlling the structure of

156
00:07:24,440 --> 00:07:26,000
Speaker 1: the interior. Usually it's the opposite.

157
00:07:26,520 --> 00:07:29,760
Speaker 2: Well, unless you're California, in which case you know, Sacramento

158
00:07:29,840 --> 00:07:31,160
Speaker 2: is the capital of the state.

159
00:07:32,280 --> 00:07:34,560
Speaker 1: Oh, maybe it's the political capital, but it's definitely not

160
00:07:34,640 --> 00:07:36,520
Speaker 1: the center of the action, that's for sure.

161
00:07:37,440 --> 00:07:39,320
Speaker 2: Yeah, it is interesting everything kind of has a center

162
00:07:39,360 --> 00:07:41,400
Speaker 2: and I guess it has to do with gravity, right, Like,

163
00:07:41,440 --> 00:07:44,840
Speaker 2: gravity is basically one of the biggest laws in the universe,

164
00:07:44,880 --> 00:07:47,200
Speaker 2: and it sort of dictates the structure of everything, right,

165
00:07:47,240 --> 00:07:49,280
Speaker 2: the structure of Earth. If we didn't have gravity, Earth

166
00:07:49,280 --> 00:07:51,320
Speaker 2: would just be a cloud of dust. And if it

167
00:07:51,360 --> 00:07:53,280
Speaker 2: wasn't for gravity, the Solar system would just be a

168
00:07:53,280 --> 00:07:56,480
Speaker 2: cloud of dust and gas. It's kind of because of gravity.

169
00:07:56,520 --> 00:07:58,040
Speaker 2: Gravity is very centralizing.

170
00:07:58,160 --> 00:07:59,960
Speaker 1: Yeah, and that's one of my favorite weird facts of

171
00:08:00,000 --> 00:08:03,040
Speaker 1: about the universe that even though gravity is the weakest

172
00:08:03,080 --> 00:08:05,960
Speaker 1: force out there by like ten to the thirty two,

173
00:08:06,160 --> 00:08:08,840
Speaker 1: you know, it's so much weaker than all the other forces,

174
00:08:09,200 --> 00:08:12,320
Speaker 1: in the end, it wins, right, It's the only force

175
00:08:12,360 --> 00:08:16,160
Speaker 1: that can't be neutralized. It can't be balanced by opposite charges.

176
00:08:16,200 --> 00:08:19,320
Speaker 1: There's only positive masses and attractive gravity, at least on

177
00:08:19,400 --> 00:08:21,920
Speaker 1: small scales, if we're going to ignore dark energy for

178
00:08:21,960 --> 00:08:25,240
Speaker 1: a while. And so it clusters things together and it

179
00:08:25,320 --> 00:08:28,040
Speaker 1: wins the race. It's patient, and it takes forever because

180
00:08:28,080 --> 00:08:31,120
Speaker 1: gravity is so weak, but eventually it dominates the whole

181
00:08:31,160 --> 00:08:34,040
Speaker 1: structure of the universe. As you say, the reason we

182
00:08:34,120 --> 00:08:37,240
Speaker 1: have solar systems and galaxies and the whole larger structure

183
00:08:37,280 --> 00:08:39,680
Speaker 1: of the universe is because of gravity. It's in charge

184
00:08:39,679 --> 00:08:40,920
Speaker 1: of organizing the universe.

185
00:08:41,520 --> 00:08:44,520
Speaker 2: You think if we didn't have gravity, we would still

186
00:08:44,559 --> 00:08:47,600
Speaker 2: be around, Like could life of form without gravity?

187
00:08:47,720 --> 00:08:51,760
Speaker 1: Life would definitely not have formed without gravity. Without gravity,

188
00:08:51,800 --> 00:08:53,200
Speaker 1: we wouldn't have stars.

189
00:08:53,360 --> 00:08:53,560
Speaker 3: Right.

190
00:08:53,679 --> 00:08:56,720
Speaker 1: Gravity is what pulled together those clouds of gas and

191
00:08:56,840 --> 00:09:00,920
Speaker 1: dust into dense packets, which started fusion, which made chemical

192
00:09:00,920 --> 00:09:03,599
Speaker 1: elements that we use for life. And without gravity, the

193
00:09:03,679 --> 00:09:07,440
Speaker 1: universe would be smoother, right, Those little extra blobs of

194
00:09:07,440 --> 00:09:10,840
Speaker 1: over density would never have turned into very hot and

195
00:09:10,960 --> 00:09:11,840
Speaker 1: dense stars.

196
00:09:12,280 --> 00:09:15,240
Speaker 2: Mmm. But could life have formed anyways in some kind

197
00:09:15,240 --> 00:09:18,200
Speaker 2: of primordial you know, galactic gas.

198
00:09:18,520 --> 00:09:20,960
Speaker 1: Perhaps so, though it would be very very different from

199
00:09:21,000 --> 00:09:23,880
Speaker 1: any life. We imagine just after the Big Bang and

200
00:09:23,920 --> 00:09:27,160
Speaker 1: before stars formed, we had only hydrogen and very very

201
00:09:27,200 --> 00:09:29,880
Speaker 1: trace amounts of anything else, a little bit of helium

202
00:09:29,920 --> 00:09:32,640
Speaker 1: and the tiniest bit of heavier stuff. And it'd be

203
00:09:32,720 --> 00:09:34,839
Speaker 1: pretty hard to form life out of just that kind

204
00:09:34,880 --> 00:09:37,360
Speaker 1: of simple basic elements. It's so much harder to build

205
00:09:37,400 --> 00:09:40,440
Speaker 1: complicated structures like the ones that our life is based on.

206
00:09:40,800 --> 00:09:43,120
Speaker 1: But it doesn't mean it's impossible. It just means life

207
00:09:43,200 --> 00:09:45,280
Speaker 1: as we know it is probably impossible.

208
00:09:45,360 --> 00:09:50,000
Speaker 2: Mmmm, you're saying, without gravity, the universe would be beige exactly.

209
00:09:50,520 --> 00:09:53,160
Speaker 2: Gravity makes things colorful. But it is an interesting question.

210
00:09:53,240 --> 00:09:56,160
Speaker 2: What does the center of the galaxy look like? I

211
00:09:56,200 --> 00:09:59,199
Speaker 2: guess we can see the center of the galaxy from Earth, right,

212
00:09:59,480 --> 00:10:01,520
Speaker 2: I mean, we're the galaxy. We should be able to

213
00:10:01,720 --> 00:10:02,960
Speaker 2: sort of know where the center is.

214
00:10:03,040 --> 00:10:05,520
Speaker 1: Well, we can look in the direction of the center

215
00:10:05,640 --> 00:10:08,520
Speaker 1: of the galaxy, but the same way that you can't always,

216
00:10:08,520 --> 00:10:12,040
Speaker 1: like see downtown from your house in the urbs, there's

217
00:10:12,080 --> 00:10:14,559
Speaker 1: often stuff in the way. Right, you can't see around

218
00:10:14,600 --> 00:10:16,960
Speaker 1: the trees and the other buildings. The center of the

219
00:10:16,960 --> 00:10:19,880
Speaker 1: galaxy is actually kind of obscured by all the gas,

220
00:10:20,040 --> 00:10:22,480
Speaker 1: the dust, and the crazy stuff that's going on between

221
00:10:22,640 --> 00:10:25,280
Speaker 1: us and it, so it's not that easy to see.

222
00:10:25,400 --> 00:10:25,559
Speaker 4: Mm.

223
00:10:26,200 --> 00:10:28,280
Speaker 2: Well, as usual, we were wondering how many people out

224
00:10:28,280 --> 00:10:31,560
Speaker 2: there had wondered what the center of the galaxy looks

225
00:10:31,679 --> 00:10:34,240
Speaker 2: like and thought about what's in there.

226
00:10:34,480 --> 00:10:37,120
Speaker 1: So thanks very much to everybody who answers these questions

227
00:10:37,120 --> 00:10:39,360
Speaker 1: for this fun segment of the podcast. If you'd like

228
00:10:39,400 --> 00:10:42,360
Speaker 1: to hear your voice, please don't be shy. Every week,

229
00:10:42,400 --> 00:10:45,240
Speaker 1: somebody writes in and says that after two years of listening.

230
00:10:45,440 --> 00:10:47,880
Speaker 1: They're finally ready to put their hat in the ring.

231
00:10:48,040 --> 00:10:50,280
Speaker 1: So let that be you and write to me at

232
00:10:50,400 --> 00:10:52,920
Speaker 1: questions at Danielandjorge dot com.

233
00:10:52,960 --> 00:10:54,600
Speaker 2: So think about it for a second. What do you

234
00:10:54,640 --> 00:10:57,920
Speaker 2: think the center of the galaxy looks like? Here's what

235
00:10:57,960 --> 00:10:58,720
Speaker 2: people have to say.

236
00:10:58,960 --> 00:11:02,520
Speaker 4: I think if you're to take radio static and change

237
00:11:02,520 --> 00:11:04,800
Speaker 4: it to visual light, it would look like that.

238
00:11:04,960 --> 00:11:07,320
Speaker 2: In terms of radio waves, I think in the middle

239
00:11:07,480 --> 00:11:10,280
Speaker 2: of the galaxy, I think there would be a lot

240
00:11:10,320 --> 00:11:12,280
Speaker 2: of radio waves, except if the black hole in the

241
00:11:12,320 --> 00:11:15,640
Speaker 2: middle absorbs them all. I feel like it be harder

242
00:11:15,679 --> 00:11:17,960
Speaker 2: to see things. I don't know, maybe the radio waves

243
00:11:17,960 --> 00:11:20,679
Speaker 2: get blocked by a lot of gas or you know,

244
00:11:20,840 --> 00:11:22,520
Speaker 2: the space space things.

245
00:11:23,040 --> 00:11:26,480
Speaker 4: I think the center of the galaxy is in a turmoil,

246
00:11:26,960 --> 00:11:31,360
Speaker 4: so it's sending out radiation on all wavelengths. So I

247
00:11:31,400 --> 00:11:34,600
Speaker 4: would guess that if we look at the center of

248
00:11:34,640 --> 00:11:40,240
Speaker 4: the galaxy in the radio wave spectrum, we should see

249
00:11:40,320 --> 00:11:42,360
Speaker 4: like a big bright spot.

250
00:11:42,600 --> 00:11:44,720
Speaker 2: All right. A lot of people seem to be talking

251
00:11:44,760 --> 00:11:47,719
Speaker 2: about radio, like is there radio in the center of

252
00:11:47,760 --> 00:11:48,280
Speaker 2: the galaxy.

253
00:11:50,160 --> 00:11:52,520
Speaker 1: They're tuned in their station to listen to the center

254
00:11:52,559 --> 00:11:53,200
Speaker 1: of the galaxy.

255
00:11:53,360 --> 00:11:56,280
Speaker 2: Be cool to be a galactic dj that's like a

256
00:11:56,280 --> 00:11:56,839
Speaker 2: cool job.

257
00:11:57,800 --> 00:12:01,120
Speaker 1: Sounds pretty intense. But they're on the right because when

258
00:12:01,120 --> 00:12:02,720
Speaker 1: we look at the center of the galaxy in the

259
00:12:02,840 --> 00:12:05,679
Speaker 1: visual light, it's not very easy to see anything, but

260
00:12:05,920 --> 00:12:08,720
Speaker 1: radio waves from the center of the galaxy can get here,

261
00:12:09,000 --> 00:12:11,080
Speaker 1: So radio is actually the best way to see the

262
00:12:11,120 --> 00:12:12,280
Speaker 1: center of the galaxy.

263
00:12:12,920 --> 00:12:15,400
Speaker 2: Interesting, and what kind of music do they play in

264
00:12:15,440 --> 00:12:19,920
Speaker 2: the center of the galaxy? Mostly fuzz, golden oldies, page oldies.

265
00:12:20,360 --> 00:12:25,160
Speaker 2: We're asking the deep questions today. What music does the

266
00:12:25,240 --> 00:12:26,080
Speaker 2: Milky Way like?

267
00:12:26,440 --> 00:12:29,240
Speaker 1: Of course, we can't hear the most modern Milky Way music.

268
00:12:29,280 --> 00:12:31,720
Speaker 1: We hear stuff that was sent to us twenty six

269
00:12:31,800 --> 00:12:35,400
Speaker 1: thousand years ago, so it's definitely oldies, though I don't

270
00:12:35,400 --> 00:12:36,440
Speaker 1: even know how gold it is.

271
00:12:36,600 --> 00:12:38,920
Speaker 2: Well, let's start with the basics, Daniel, take us on

272
00:12:38,960 --> 00:12:40,800
Speaker 2: a trip. What does it mean for the galaxy to

273
00:12:40,840 --> 00:12:41,520
Speaker 2: have a center?

274
00:12:41,679 --> 00:12:43,360
Speaker 1: So people have been trying to figure this out for

275
00:12:43,440 --> 00:12:45,760
Speaker 1: several hundred years. People look up at the night sky

276
00:12:45,960 --> 00:12:48,720
Speaker 1: and see the stars and then wonder, like, where is

277
00:12:48,800 --> 00:12:51,280
Speaker 1: the sun in our neighborhood. Is it just a bunch

278
00:12:51,320 --> 00:12:53,640
Speaker 1: of stars sprinkle out through the universe? Is there a

279
00:12:53,679 --> 00:12:56,600
Speaker 1: collection of stuff? Is there one spot that's more interesting

280
00:12:56,760 --> 00:12:59,240
Speaker 1: than another. So for the last couple hundred years, people

281
00:12:59,240 --> 00:13:01,319
Speaker 1: have been building the star maps and trying to gain

282
00:13:01,360 --> 00:13:04,320
Speaker 1: a sense of where we are. I remember, it was

283
00:13:04,360 --> 00:13:06,920
Speaker 1: only like one hundred years ago that we realized that

284
00:13:07,000 --> 00:13:09,640
Speaker 1: we were in a galaxy. That's when Hubble noticed that

285
00:13:09,720 --> 00:13:11,600
Speaker 1: some of the smudges that are up there in the

286
00:13:11,640 --> 00:13:14,280
Speaker 1: sky that look just like clouds of gas and dust,

287
00:13:14,440 --> 00:13:18,480
Speaker 1: are actually super duper far away. They're actually outside of

288
00:13:18,559 --> 00:13:21,000
Speaker 1: our galaxy. That's when we first realized that we have

289
00:13:21,040 --> 00:13:23,160
Speaker 1: a galaxy, this blob of stars, and that there are

290
00:13:23,240 --> 00:13:25,800
Speaker 1: other galaxies out there, so that our galaxy is just

291
00:13:26,360 --> 00:13:29,280
Speaker 1: one of many. And people have continued making maps of

292
00:13:29,280 --> 00:13:31,360
Speaker 1: the stars, so trying to get a picture of what

293
00:13:31,440 --> 00:13:34,320
Speaker 1: our galaxy looks like, which is complicated because of course

294
00:13:34,360 --> 00:13:37,440
Speaker 1: we're inside the galaxy, so we can't like ever step

295
00:13:37,480 --> 00:13:40,040
Speaker 1: outside and see what it looks like. We can only

296
00:13:40,080 --> 00:13:42,440
Speaker 1: map it from the inside, which is a challenge.

297
00:13:42,640 --> 00:13:45,559
Speaker 2: Yeah, it's interesting to think about what people thought about

298
00:13:45,679 --> 00:13:48,880
Speaker 2: before we need other galaxies, right, Like, are there scientific

299
00:13:48,880 --> 00:13:51,679
Speaker 2: papers from that time or people writing about it. Did

300
00:13:51,720 --> 00:13:54,600
Speaker 2: we think that we were in like a cloud of

301
00:13:54,640 --> 00:13:58,440
Speaker 2: stars or just an infinite space filled with stars? What

302
00:13:58,520 --> 00:14:02,080
Speaker 2: was the general thinking about what the rest of the

303
00:14:02,160 --> 00:14:04,479
Speaker 2: universe looked like before we knew there were other galaxies.

304
00:14:04,559 --> 00:14:06,720
Speaker 1: Yeah, it's a great question. The first sort of maps

305
00:14:06,720 --> 00:14:09,560
Speaker 1: were from like the late seventeen hundreds. A guy named

306
00:14:09,559 --> 00:14:11,640
Speaker 1: Herschel sort of drew all the stars that you could

307
00:14:11,640 --> 00:14:14,360
Speaker 1: see and mid like the first map of these stars

308
00:14:14,480 --> 00:14:17,320
Speaker 1: try to orient where the sun was, and we just

309
00:14:17,360 --> 00:14:19,360
Speaker 1: really couldn't see very far, so we didn't have a

310
00:14:19,440 --> 00:14:22,160
Speaker 1: sense for what was going on beyond that, and people

311
00:14:22,200 --> 00:14:25,000
Speaker 1: imagine that all of space was just filled with stars

312
00:14:25,000 --> 00:14:26,880
Speaker 1: that just sort of like hung out there. But then

313
00:14:26,880 --> 00:14:28,920
Speaker 1: people noticed this, like, oh, there's this disk in the

314
00:14:28,960 --> 00:14:31,600
Speaker 1: middle right where the stars get denser. So as our

315
00:14:31,640 --> 00:14:34,040
Speaker 1: ability to see things got better, we were able to

316
00:14:34,240 --> 00:14:36,600
Speaker 1: notice more and more that there was a pattern things

317
00:14:36,640 --> 00:14:39,120
Speaker 1: got denser in one direction, and so like in the

318
00:14:39,160 --> 00:14:42,360
Speaker 1: early nineteen hundreds, we have more detailed catalogs that show

319
00:14:42,400 --> 00:14:44,520
Speaker 1: us that the stars are not just sprinkled out through

320
00:14:44,520 --> 00:14:46,680
Speaker 1: the whole universe, but that there's sort of a flat

321
00:14:46,760 --> 00:14:47,680
Speaker 1: disc structure.

322
00:14:47,880 --> 00:14:50,600
Speaker 2: And this all came about because of photography. I think, right,

323
00:14:50,680 --> 00:14:52,720
Speaker 2: like you just look with your naked eye at the

324
00:14:52,800 --> 00:14:54,920
Speaker 2: night sky. You see some stars, but it's only when

325
00:14:54,920 --> 00:14:57,520
Speaker 2: you sort of have a photography setup and you can

326
00:14:57,600 --> 00:15:00,920
Speaker 2: expose a sheet of paper or photo paper for a

327
00:15:00,920 --> 00:15:03,200
Speaker 2: long time do you get to sort of see really

328
00:15:03,240 --> 00:15:04,240
Speaker 2: what's out there. Right.

329
00:15:04,320 --> 00:15:06,880
Speaker 1: Yeah, the name of the game is capturing more light,

330
00:15:07,040 --> 00:15:09,640
Speaker 1: and you can do that by longer exposure. And you

331
00:15:09,680 --> 00:15:12,680
Speaker 1: can also do that by having a larger aperture. So

332
00:15:12,760 --> 00:15:17,000
Speaker 1: building telescopes with larger light gathering capacities is also key.

333
00:15:17,040 --> 00:15:18,920
Speaker 1: If you're going to gather light over time, you need

334
00:15:18,960 --> 00:15:21,320
Speaker 1: to also track the objects. It doesn't make a smear

335
00:15:21,440 --> 00:15:23,800
Speaker 1: in your photograph, but both of those things are crucial.

336
00:15:23,960 --> 00:15:27,000
Speaker 1: Gathering light over time and having a larger aperture that

337
00:15:27,120 --> 00:15:30,280
Speaker 1: lets you see dimmer things which are further away things,

338
00:15:30,520 --> 00:15:32,680
Speaker 1: which lets you expand the sort of mental map in

339
00:15:32,720 --> 00:15:35,800
Speaker 1: your mind of where we are, what our cosmic neighborhood is.

340
00:15:36,240 --> 00:15:38,880
Speaker 2: And I guess before we would look at the Milky Way.

341
00:15:39,120 --> 00:15:40,880
Speaker 2: Like the Milky Way you can't see with your naked

342
00:15:40,920 --> 00:15:43,080
Speaker 2: eye on a super clear night, right if you are

343
00:15:43,120 --> 00:15:44,600
Speaker 2: in the middle of nowhere, you can see sort of

344
00:15:44,600 --> 00:15:47,640
Speaker 2: a white streak across the sky. Did people think that

345
00:15:47,640 --> 00:15:50,400
Speaker 2: that was just like some sort of galactic cloud or

346
00:15:50,400 --> 00:15:52,680
Speaker 2: did they have an intuition like, oh, my goodness, there's

347
00:15:52,880 --> 00:15:54,280
Speaker 2: tons of stars in that strip.

348
00:15:54,440 --> 00:15:57,560
Speaker 1: Well, once we identified other galaxies, we could study them,

349
00:15:57,600 --> 00:15:59,160
Speaker 1: and that gave us a lot of clues about the

350
00:15:59,240 --> 00:16:02,120
Speaker 1: nature of our galaxy. The same way that like, once

351
00:16:02,160 --> 00:16:04,240
Speaker 1: you look at other planets, you notice, oh boy, those

352
00:16:04,280 --> 00:16:08,600
Speaker 1: are around Probably our planet is round two really solidifies

353
00:16:08,640 --> 00:16:10,760
Speaker 1: the idea that planets are spears, right when you can

354
00:16:10,760 --> 00:16:13,800
Speaker 1: see other planets being spears. So when we could study,

355
00:16:13,800 --> 00:16:16,600
Speaker 1: for example, Andromeda, because we had telescopes, we could see, oh, look,

356
00:16:16,680 --> 00:16:19,120
Speaker 1: that looks like a big flat disc with all these

357
00:16:19,120 --> 00:16:23,240
Speaker 1: spiral arms. That's a very strong clue that maybe our galaxy.

358
00:16:22,800 --> 00:16:23,880
Speaker 2: Looks like that also.

359
00:16:24,120 --> 00:16:25,720
Speaker 1: And then you could look up at the night sky

360
00:16:25,840 --> 00:16:27,960
Speaker 1: you can see the pattern of stars, so you can

361
00:16:28,000 --> 00:16:30,920
Speaker 1: fit it into that shape. And in fact, our galaxy

362
00:16:30,960 --> 00:16:33,640
Speaker 1: looks a lot like Andromeda. I mean, it's smaller, but

363
00:16:33,720 --> 00:16:36,400
Speaker 1: it has roughly the same shape. It's a big elliptical

364
00:16:36,480 --> 00:16:39,520
Speaker 1: swirl with a central blob and a few arms that

365
00:16:39,720 --> 00:16:40,400
Speaker 1: spiral out.

366
00:16:41,160 --> 00:16:42,880
Speaker 2: So those two things sort of came about at the

367
00:16:42,920 --> 00:16:45,240
Speaker 2: same time, like we noticed that in this direction there's

368
00:16:45,280 --> 00:16:48,320
Speaker 2: a whole bunch more stars, and also, hey, we're a galaxy.

369
00:16:48,400 --> 00:16:50,440
Speaker 2: So maybe this direction is where the center of the

370
00:16:50,480 --> 00:16:51,040
Speaker 2: galaxy is.

371
00:16:51,200 --> 00:16:53,800
Speaker 1: Yeah, that kind of understanding really crystallized in the early

372
00:16:53,880 --> 00:16:56,160
Speaker 1: nineteen hundreds, and now we have a pretty good map

373
00:16:56,200 --> 00:16:59,960
Speaker 1: of the galaxy. Very recently, there's a spacecraft called Gaya

374
00:17:00,080 --> 00:17:03,160
Speaker 1: which is doing a super precise map of billions of

375
00:17:03,240 --> 00:17:05,359
Speaker 1: stars to give us a very accurate picture of our

376
00:17:05,400 --> 00:17:08,359
Speaker 1: galactic neighborhood. Un let's ask all sorts of really fun

377
00:17:08,400 --> 00:17:11,159
Speaker 1: interesting questions. But we now know that we live like

378
00:17:11,240 --> 00:17:14,400
Speaker 1: sort of halfway out from the center of the galaxy

379
00:17:14,560 --> 00:17:17,040
Speaker 1: along one of these spiral arms.

380
00:17:17,720 --> 00:17:20,560
Speaker 2: Yeah, break down what we know about the Milky Way.

381
00:17:20,720 --> 00:17:24,520
Speaker 2: So it's like a cluster of stars, but it's sort

382
00:17:24,560 --> 00:17:26,840
Speaker 2: of flat shape, right, It sort of looks like a disc,

383
00:17:27,040 --> 00:17:29,520
Speaker 2: but it's not a perfect disc because it's sort of

384
00:17:29,640 --> 00:17:32,080
Speaker 2: organized in terms of streaks or swirls.

385
00:17:32,200 --> 00:17:34,800
Speaker 1: Right, Yeah, it's not even a perfectly flat disc. Remember

386
00:17:34,800 --> 00:17:36,880
Speaker 1: we did an episode about how the Milky Way itself

387
00:17:37,240 --> 00:17:39,040
Speaker 1: is a little bit twisted. It's sort of like a

388
00:17:39,119 --> 00:17:41,399
Speaker 1: hat where it's like tilted up on one side and

389
00:17:41,400 --> 00:17:44,560
Speaker 1: tilted down on the other side. Maybe because of recent

390
00:17:44,640 --> 00:17:47,480
Speaker 1: mergers or gravitational interactions with other galaxies.

391
00:17:47,560 --> 00:17:48,919
Speaker 2: Wait, like a horse saddle kind of.

392
00:17:48,960 --> 00:17:50,600
Speaker 1: Yeah, sort of, it's like tilted up on one side

393
00:17:50,640 --> 00:17:52,240
Speaker 1: and tilts it down on the other side.

394
00:17:52,600 --> 00:17:55,040
Speaker 2: Whoa, we have like a cowboy milky way.

395
00:17:55,160 --> 00:17:57,919
Speaker 1: Yeah, exactly. It's got a little flare to it. So

396
00:17:57,960 --> 00:18:00,440
Speaker 1: that's the disc. It's mostly a disc, but this little

397
00:18:00,440 --> 00:18:02,359
Speaker 1: bit of a tweak to it. But then, as you say,

398
00:18:02,400 --> 00:18:05,760
Speaker 1: the disc itself is not perfectly smooth. We have these arms.

399
00:18:06,119 --> 00:18:08,879
Speaker 1: So there's like a central bulge, a big blob in

400
00:18:08,920 --> 00:18:11,600
Speaker 1: the center of stars, and then that's surrounded by a

401
00:18:11,640 --> 00:18:15,639
Speaker 1: central bar. It's like long bar of stars, which is

402
00:18:15,680 --> 00:18:20,000
Speaker 1: itself embedded in the nuclear bulge, which is like circular

403
00:18:20,040 --> 00:18:21,760
Speaker 1: blob at the very center of the galaxy.

404
00:18:21,840 --> 00:18:23,600
Speaker 2: Wait, what do you mean like a bar like two

405
00:18:23,920 --> 00:18:25,840
Speaker 2: arms that shoot straight out from the center.

406
00:18:25,920 --> 00:18:27,960
Speaker 1: Yeah, they're not really called arms. They're sort of short

407
00:18:28,000 --> 00:18:30,920
Speaker 1: compared to what we call the galactic arms themselves. But yeah,

408
00:18:30,920 --> 00:18:33,639
Speaker 1: it's two lines that shoot out from the center, and

409
00:18:33,720 --> 00:18:37,040
Speaker 1: it's embedded inside this larger nuclear bulge. So we have

410
00:18:37,080 --> 00:18:39,440
Speaker 1: this central bar and a nuclear.

411
00:18:39,080 --> 00:18:41,359
Speaker 2: Bulge sort of like if you took a pen and

412
00:18:41,400 --> 00:18:45,480
Speaker 2: stabbed it through an orange. That's kind of what it looks, I.

413
00:18:45,400 --> 00:18:47,000
Speaker 1: Guess so I think of it more like a half

414
00:18:47,040 --> 00:18:49,800
Speaker 1: closed eye, you know, has like a slit through it.

415
00:18:50,000 --> 00:18:53,120
Speaker 2: All right. So then so we're about halfway out from

416
00:18:53,119 --> 00:18:54,200
Speaker 2: the center to the edge.

417
00:18:54,320 --> 00:18:56,200
Speaker 1: Yeah, this central blob sort of looks like an eye

418
00:18:56,280 --> 00:18:58,439
Speaker 1: winking at you, and then you have these arms that

419
00:18:58,520 --> 00:19:01,199
Speaker 1: shoot out from it. The Milky Way has four of

420
00:19:01,240 --> 00:19:05,440
Speaker 1: these arms. They start at this nuclear bulge, either the

421
00:19:05,440 --> 00:19:08,280
Speaker 1: orange or the eyeball, whgever you prefer, and then they

422
00:19:08,320 --> 00:19:11,520
Speaker 1: streak out, they swirl around the center. And so there's

423
00:19:11,560 --> 00:19:14,000
Speaker 1: four of these arms. And we actually live on a

424
00:19:14,119 --> 00:19:16,480
Speaker 1: spur that comes off of one of those arms. We

425
00:19:16,520 --> 00:19:18,879
Speaker 1: don't even live on one of those arms.

426
00:19:19,000 --> 00:19:22,440
Speaker 2: Whoa, we're like in the suburb of the suburb exactly.

427
00:19:22,760 --> 00:19:25,520
Speaker 1: It's called the Orion spur. So when you're camping and

428
00:19:25,560 --> 00:19:27,200
Speaker 1: it's very dark and you look up at the night

429
00:19:27,280 --> 00:19:30,080
Speaker 1: sky and you see this white streak that we call

430
00:19:30,160 --> 00:19:33,119
Speaker 1: the milky Way, which you're looking at is the next

431
00:19:33,359 --> 00:19:36,520
Speaker 1: arm over you're looking towards the center of the galaxy

432
00:19:36,880 --> 00:19:38,840
Speaker 1: and you're looking at the next arm.

433
00:19:39,080 --> 00:19:41,239
Speaker 2: Well, you're sort of looking at all of it, aren't you, Like,

434
00:19:41,560 --> 00:19:43,520
Speaker 2: isn't some of that also the center of the galaxy

435
00:19:43,600 --> 00:19:45,200
Speaker 2: coming through and hitting your eyeballs.

436
00:19:45,280 --> 00:19:47,360
Speaker 1: Well, you're looking through everything, of course, and so you're

437
00:19:47,400 --> 00:19:50,520
Speaker 1: seeing nearby stars that are in our arm. Those are

438
00:19:50,520 --> 00:19:53,080
Speaker 1: the stars you see. And then you also see sort

439
00:19:53,080 --> 00:19:55,440
Speaker 1: of the outer edge of the next arm. But these

440
00:19:55,560 --> 00:19:58,280
Speaker 1: arms have gas and dust in them, and so it's

441
00:19:58,280 --> 00:20:00,439
Speaker 1: hard to see all the way through them. Some of

442
00:20:00,440 --> 00:20:02,920
Speaker 1: the light from the center also does make it through,

443
00:20:03,520 --> 00:20:06,600
Speaker 1: but this gas and dust is really good at obscuring

444
00:20:06,640 --> 00:20:09,000
Speaker 1: the light behind it, so it's very difficult to see

445
00:20:09,040 --> 00:20:10,880
Speaker 1: all the way through it. So none of the light

446
00:20:10,880 --> 00:20:13,520
Speaker 1: that hits your eyeball really is coming from the center

447
00:20:13,560 --> 00:20:15,879
Speaker 1: of the galaxy. It's in the direction of the center

448
00:20:15,920 --> 00:20:18,479
Speaker 1: of the galaxy. But you're seeing the stuff that's between

449
00:20:18,560 --> 00:20:21,920
Speaker 1: us and the center mostly, right. I mean, there might

450
00:20:21,920 --> 00:20:24,880
Speaker 1: be some light that's coming through, Yes, there might be some,

451
00:20:25,000 --> 00:20:29,280
Speaker 1: but visible light is really really quenched by the galactic dust.

452
00:20:29,480 --> 00:20:31,480
Speaker 2: All right, Well, I guess that begs the question what

453
00:20:31,640 --> 00:20:33,840
Speaker 2: is going on there in the center of the galaxy?

454
00:20:33,960 --> 00:20:36,639
Speaker 2: What can we see? And most important, at least for me,

455
00:20:36,880 --> 00:20:38,760
Speaker 2: is how do we know this If we're in the

456
00:20:38,760 --> 00:20:40,960
Speaker 2: Milky Way galaxy? How do we know what the Milky

457
00:20:41,000 --> 00:20:44,159
Speaker 2: Way galaxy looks like? So let's get into that, but

458
00:20:44,240 --> 00:20:59,240
Speaker 2: first let's take a quick break. All right, we're talking

459
00:20:59,280 --> 00:21:02,119
Speaker 2: about the center of the galaxy and how it's a

460
00:21:02,119 --> 00:21:04,600
Speaker 2: lot more exciting there. Are you suffering from some sort

461
00:21:04,640 --> 00:21:08,040
Speaker 2: of galactic fomo fear of missing out?

462
00:21:10,359 --> 00:21:13,720
Speaker 1: No, I'm pretty happy here on Earth. The galactic center

463
00:21:13,800 --> 00:21:16,160
Speaker 1: is kind of a crazy place, lots of pulsing, lots

464
00:21:16,200 --> 00:21:19,080
Speaker 1: of radiation. Not a place that I would survive very long.

465
00:21:19,240 --> 00:21:20,920
Speaker 2: But if you're in Irvine, that means you're in sort

466
00:21:20,960 --> 00:21:23,480
Speaker 2: of like the suburb of the suburb of the suburb

467
00:21:23,680 --> 00:21:25,240
Speaker 2: of the suburb of the galaxy.

468
00:21:25,320 --> 00:21:26,760
Speaker 1: Yeah, it turns out it's a pretty nice place to

469
00:21:26,800 --> 00:21:28,000
Speaker 1: raise kids, So I'm not too.

470
00:21:27,880 --> 00:21:31,240
Speaker 2: Really happy it's a super suburb. Yeah.

471
00:21:31,240 --> 00:21:33,840
Speaker 1: So we turn out to be about twenty six thousand

472
00:21:33,960 --> 00:21:37,199
Speaker 1: light years away from the center of the galaxy. The

473
00:21:37,240 --> 00:21:40,080
Speaker 1: whole galaxy is like one hundred thousand light years across,

474
00:21:40,560 --> 00:21:43,320
Speaker 1: so we're like halfway between the center and like sort

475
00:21:43,320 --> 00:21:45,800
Speaker 1: of the outskirts, the last visible stars.

476
00:21:46,080 --> 00:21:49,200
Speaker 2: And so how do you define what the center of

477
00:21:49,240 --> 00:21:50,200
Speaker 2: the galaxy is?

478
00:21:50,320 --> 00:21:50,399
Speaker 3: Like?

479
00:21:50,560 --> 00:21:53,639
Speaker 2: Is there a limit? Does it get super dense all

480
00:21:53,640 --> 00:21:55,240
Speaker 2: of a sudden as you go towards the center? Is

481
00:21:55,280 --> 00:21:57,680
Speaker 2: there like a ball in the middle of stars or

482
00:21:57,720 --> 00:21:58,800
Speaker 2: is it pretty fuzzy.

483
00:21:58,960 --> 00:22:00,920
Speaker 1: So there's a few ways to define it. One way

484
00:22:01,000 --> 00:22:04,280
Speaker 1: is the geometrical center, to say, like, here's the whole

485
00:22:04,320 --> 00:22:07,280
Speaker 1: Milky Way, what's literally at the center. And that's like

486
00:22:07,320 --> 00:22:10,120
Speaker 1: taking the United States and saying, okay, Kansas is the

487
00:22:10,119 --> 00:22:11,320
Speaker 1: center of the United States.

488
00:22:11,320 --> 00:22:12,720
Speaker 2: It's literally in the middle.

489
00:22:12,960 --> 00:22:16,720
Speaker 1: A more sensible way to define it is the gravitational center.

490
00:22:16,880 --> 00:22:18,960
Speaker 1: To add up all the stuff in the Milky Way

491
00:22:19,040 --> 00:22:22,199
Speaker 1: and wait its location by its gravity, and find like

492
00:22:22,240 --> 00:22:24,800
Speaker 1: the center of mass of the Milky Way, like the

493
00:22:24,840 --> 00:22:27,720
Speaker 1: point around which everything is spinning.

494
00:22:27,400 --> 00:22:30,760
Speaker 2: Which might be different than the geographical location.

495
00:22:31,040 --> 00:22:32,840
Speaker 1: In principle, it could be different. If the Milky Way

496
00:22:32,920 --> 00:22:36,320
Speaker 1: was asymmetric somehow, then it could be different. We think

497
00:22:36,359 --> 00:22:39,440
Speaker 1: in our case that those two things mostly line up

498
00:22:39,880 --> 00:22:42,080
Speaker 1: because the density profile of the Milky Way is that

499
00:22:42,119 --> 00:22:45,560
Speaker 1: it's densest at the center and mostly symmetric as it

500
00:22:45,600 --> 00:22:48,280
Speaker 1: goes out. Then there's the definition of the center of

501
00:22:48,320 --> 00:22:51,440
Speaker 1: the galaxy. And astronomers have just like picked a spot

502
00:22:51,480 --> 00:22:54,480
Speaker 1: it's called Sagittarius A and it's a radio emitter, and

503
00:22:54,520 --> 00:22:57,560
Speaker 1: said we define this to be the center of the galaxy.

504
00:22:57,560 --> 00:23:00,679
Speaker 1: It's like the coordinate system. That's a little arbitrary. You

505
00:23:00,680 --> 00:23:03,080
Speaker 1: could put it anywhere, but everybody has to agree on

506
00:23:03,160 --> 00:23:05,520
Speaker 1: an exact location, and so that's where they put it.

507
00:23:05,600 --> 00:23:07,600
Speaker 2: Wait, there's a star in the middle of the galaxy

508
00:23:07,600 --> 00:23:11,320
Speaker 2: that we can make out and see. Well, there's a

509
00:23:11,440 --> 00:23:12,600
Speaker 2: radio source, right.

510
00:23:12,640 --> 00:23:14,480
Speaker 1: And when people started to look up at the night

511
00:23:14,520 --> 00:23:16,600
Speaker 1: sky and realize that we could look at the night

512
00:23:16,640 --> 00:23:20,439
Speaker 1: sky in other wavelengths than just visible light, they started

513
00:23:20,440 --> 00:23:24,679
Speaker 1: to build radio telescopes to listen to radio waves from space.

514
00:23:25,040 --> 00:23:28,520
Speaker 1: They noticed a very bright source of radio waves coming

515
00:23:28,800 --> 00:23:31,280
Speaker 1: from the direction of the center of the galaxy. So

516
00:23:31,280 --> 00:23:34,639
Speaker 1: that's what we call Sagittarius A. It's a bright radio

517
00:23:34,720 --> 00:23:37,600
Speaker 1: source and that's where we put the center of the galaxy.

518
00:23:37,840 --> 00:23:40,320
Speaker 1: So it's not a star, it's a radio source.

519
00:23:41,520 --> 00:23:44,080
Speaker 2: I guess we'll dig into what it actually is, maybe

520
00:23:44,119 --> 00:23:46,080
Speaker 2: step us through what is at the center? Then? Is

521
00:23:46,119 --> 00:23:48,440
Speaker 2: it like a cluster stars? There's a big black hole

522
00:23:48,480 --> 00:23:48,920
Speaker 2: there too.

523
00:23:48,880 --> 00:23:50,840
Speaker 1: Right, So there is a big black hole and that's

524
00:23:50,880 --> 00:23:55,560
Speaker 1: what's generating all those radio emissions. Sagittarius A star is

525
00:23:55,720 --> 00:23:59,240
Speaker 1: the black hole at Sagittarius A, which is the radio emitter.

526
00:23:59,359 --> 00:24:00,600
Speaker 2: And so there's a huge black hole.

527
00:24:00,640 --> 00:24:04,040
Speaker 1: There are almost five million solar masses. That's the densest

528
00:24:04,080 --> 00:24:07,439
Speaker 1: part of the galaxy. But the whole blob near the

529
00:24:07,480 --> 00:24:10,840
Speaker 1: center is very, very dense with stars. There's like ten

530
00:24:10,960 --> 00:24:14,600
Speaker 1: million stars in the sort of central cubic parsec and

531
00:24:14,880 --> 00:24:16,960
Speaker 1: parsek is around three light years.

532
00:24:17,080 --> 00:24:23,200
Speaker 2: Wait, there's ten million stars per cubic parsk near the center.

533
00:24:23,400 --> 00:24:26,439
Speaker 1: Yeah, exactly, so that's about a million stars per cubic

534
00:24:26,520 --> 00:24:26,960
Speaker 1: light year.

535
00:24:27,080 --> 00:24:29,439
Speaker 2: How dense is that? Like, if we were there, would

536
00:24:29,480 --> 00:24:32,760
Speaker 2: we just be toast? Would it be super bright? Could

537
00:24:32,760 --> 00:24:35,560
Speaker 2: you survive? Could there be like an Earth there? Or

538
00:24:35,600 --> 00:24:37,160
Speaker 2: would it just be too intense?

539
00:24:37,240 --> 00:24:40,080
Speaker 1: It would be really intense. The density around here is

540
00:24:40,200 --> 00:24:42,600
Speaker 1: much much lower. It's like three or four light years

541
00:24:42,640 --> 00:24:45,679
Speaker 1: to the nearest star, so the density around here is

542
00:24:45,720 --> 00:24:48,760
Speaker 1: like less than one star per cubic parsec. There, it's

543
00:24:48,800 --> 00:24:53,400
Speaker 1: ten million stars per cubic parsec, so it's much more intense.

544
00:24:53,880 --> 00:24:56,960
Speaker 1: The light and the other forms of radiation are crazy

545
00:24:57,040 --> 00:24:59,280
Speaker 1: in the center of the galaxy. It's hard to imagine

546
00:24:59,359 --> 00:25:03,919
Speaker 1: lifelike ours thriving or surviving even in the middle of

547
00:25:03,960 --> 00:25:04,520
Speaker 1: the galaxy.

548
00:25:04,680 --> 00:25:07,120
Speaker 2: Well, it'd be super bright, but I wonder, are there

549
00:25:07,200 --> 00:25:09,280
Speaker 2: still I mean there are still stars there, so there

550
00:25:09,359 --> 00:25:13,000
Speaker 2: must be solar systems, right, and planets there just be

551
00:25:13,080 --> 00:25:14,400
Speaker 2: super bright everywhere you look.

552
00:25:14,760 --> 00:25:16,840
Speaker 1: There are definitely stars there, and we can see some

553
00:25:16,960 --> 00:25:19,399
Speaker 1: of them, like there's this star S two that we

554
00:25:19,440 --> 00:25:22,719
Speaker 1: see orbiting the central black hole, and by watching it

555
00:25:22,800 --> 00:25:25,359
Speaker 1: move we can tell how massive that black hole is.

556
00:25:25,480 --> 00:25:28,480
Speaker 1: Are there solar systems there? Is harder to answer because

557
00:25:28,480 --> 00:25:32,440
Speaker 1: the crazy intense environment is not very conducive to stable orbits. Remember,

558
00:25:32,440 --> 00:25:35,480
Speaker 1: if another star comes near our solar system, it could

559
00:25:35,520 --> 00:25:38,440
Speaker 1: disrupt Earth's orbit or Jupiter's orbit and we could lose

560
00:25:38,480 --> 00:25:40,639
Speaker 1: a planet. So in an environment where there are so

561
00:25:40,800 --> 00:25:43,560
Speaker 1: many stars jostling around each other, it's probably a lot

562
00:25:43,600 --> 00:25:45,480
Speaker 1: harder to hold onto planets.

563
00:25:45,800 --> 00:25:47,800
Speaker 2: So maybe can you paint as a picture like how

564
00:25:47,840 --> 00:25:50,000
Speaker 2: close are these solar systems together? Like if you were

565
00:25:50,000 --> 00:25:52,159
Speaker 2: in a solar system like ours, how close would the

566
00:25:52,240 --> 00:25:55,840
Speaker 2: next solar system be, like several solar systems away or

567
00:25:56,000 --> 00:25:57,679
Speaker 2: right next door? Or are they all sort of bunched

568
00:25:57,680 --> 00:25:58,879
Speaker 2: together or what's going on?

569
00:25:59,040 --> 00:26:02,200
Speaker 1: Yeah, the density of stars is literally ten million times

570
00:26:02,240 --> 00:26:05,360
Speaker 1: as dense as it is here. Ten million times denser

571
00:26:05,520 --> 00:26:09,639
Speaker 1: means stars are on average two hundred times closer together,

572
00:26:10,200 --> 00:26:13,200
Speaker 1: So instead of having a few light years between stars,

573
00:26:13,480 --> 00:26:16,960
Speaker 1: the average distance between stars is like two percent of

574
00:26:16,960 --> 00:26:20,040
Speaker 1: a light year, which is like twenty five times the

575
00:26:20,160 --> 00:26:23,239
Speaker 1: radius of Pluto's orbit. So other stars are not like

576
00:26:23,400 --> 00:26:26,920
Speaker 1: literally next door, but they're much closer than around here,

577
00:26:27,119 --> 00:26:30,240
Speaker 1: where the next star over is like five thousand Pluto orbits.

578
00:26:30,600 --> 00:26:32,800
Speaker 1: So there'd be a lot more stars a lot brighter,

579
00:26:32,960 --> 00:26:35,040
Speaker 1: Like there would be no darkness on a planet orbiting

580
00:26:35,080 --> 00:26:37,119
Speaker 1: one of those stars because the night sky would be

581
00:26:37,200 --> 00:26:40,560
Speaker 1: so bright with stars that would be so close. Remember,

582
00:26:40,600 --> 00:26:44,159
Speaker 1: when stars get closer, they get brighter fast because the

583
00:26:44,160 --> 00:26:47,080
Speaker 1: brightness goes as the distance squared, So if a star

584
00:26:47,119 --> 00:26:50,040
Speaker 1: gets ten times closer, it's one hundred times brighter.

585
00:26:50,080 --> 00:26:51,720
Speaker 2: Well, I guess it's all relative, right, Like if you

586
00:26:51,760 --> 00:26:56,800
Speaker 2: were sunglasses, Yeah, it might look just like it here.

587
00:26:57,320 --> 00:26:59,359
Speaker 1: Yeah, But the stars there are also different from the

588
00:26:59,400 --> 00:27:01,879
Speaker 1: stars here because it's not a very good place to

589
00:27:02,000 --> 00:27:05,200
Speaker 1: make stars because it's so crazy and there's so much radiation.

590
00:27:05,560 --> 00:27:08,080
Speaker 1: And remember that to make stars you need like cold

591
00:27:08,280 --> 00:27:11,360
Speaker 1: gas that can very gradually get pulled together by gravity.

592
00:27:11,800 --> 00:27:13,679
Speaker 1: So most of the stars in the center of the

593
00:27:13,680 --> 00:27:16,919
Speaker 1: galaxy are old stars because it's not a star forming region.

594
00:27:17,359 --> 00:27:21,159
Speaker 1: So you have these really old, small red stars, so

595
00:27:21,200 --> 00:27:24,880
Speaker 1: they're dimmer and they're redder, but there's a lot of them.

596
00:27:24,920 --> 00:27:27,600
Speaker 2: You mean, like they were formed outside of the center

597
00:27:27,680 --> 00:27:30,560
Speaker 2: and then they all congregated in the middle because of gravity.

598
00:27:30,920 --> 00:27:33,160
Speaker 1: Yeah, or they were formed when the center wasn't as

599
00:27:33,280 --> 00:27:36,439
Speaker 1: crazy during early days of the Milky Way. Remember the

600
00:27:36,440 --> 00:27:39,400
Speaker 1: Milky Way is almost as old as the universe. It's

601
00:27:39,400 --> 00:27:42,600
Speaker 1: like thirteen billion years old, and some of the stars

602
00:27:42,640 --> 00:27:45,119
Speaker 1: in the center might be about as old as the

603
00:27:45,160 --> 00:27:48,119
Speaker 1: Milky Way itself. Stars that are small can burn for

604
00:27:48,280 --> 00:27:50,920
Speaker 1: billions and billions of years. We think our star is

605
00:27:50,960 --> 00:27:53,560
Speaker 1: going to burn for about ten billion, but our star

606
00:27:53,640 --> 00:27:56,280
Speaker 1: is a little bit heavier than the typical star. Most stars,

607
00:27:56,320 --> 00:27:59,480
Speaker 1: like red dwarfs could burn for much longer and may

608
00:27:59,480 --> 00:28:02,159
Speaker 1: have been around at the very formation of the galaxy.

609
00:28:02,680 --> 00:28:05,639
Speaker 1: So those stars could predate the galaxy having like an

610
00:28:05,720 --> 00:28:07,480
Speaker 1: active center, you know, just the way you could have

611
00:28:07,520 --> 00:28:09,639
Speaker 1: like an old building in the center of downtown with

612
00:28:09,760 --> 00:28:11,600
Speaker 1: all these skyscrapers built around it.

613
00:28:11,640 --> 00:28:13,480
Speaker 2: But of course here in La all the stars live

614
00:28:13,480 --> 00:28:19,160
Speaker 2: in Beverly Hills and up in the Hollywood Hills, and

615
00:28:19,240 --> 00:28:22,360
Speaker 2: some in Pasadena. Know the big podcast stars all live

616
00:28:22,400 --> 00:28:25,199
Speaker 2: in South Pasadena. All right, So that's the center of

617
00:28:25,240 --> 00:28:27,760
Speaker 2: the galaxy. There's a big black hole there, and it's

618
00:28:28,240 --> 00:28:30,800
Speaker 2: chalk full of stars. I guess my biggest question is,

619
00:28:30,840 --> 00:28:33,159
Speaker 2: like how do we know all of these things? Like

620
00:28:33,200 --> 00:28:35,760
Speaker 2: how can you tell what's there or what the structure

621
00:28:36,640 --> 00:28:39,000
Speaker 2: the whole galaxy looks like if we're in the middle

622
00:28:39,040 --> 00:28:41,240
Speaker 2: of it, you know, like you can't take a selfie.

623
00:28:41,240 --> 00:28:43,200
Speaker 2: We haven't taken a selfie. How do we know about

624
00:28:43,200 --> 00:28:46,560
Speaker 2: all these structures like the arms and the orion spur, Like,

625
00:28:46,560 --> 00:28:48,600
Speaker 2: how do we know all of this, you know, sort

626
00:28:48,600 --> 00:28:50,680
Speaker 2: of detailed structure if we're in the middle of it.

627
00:28:50,880 --> 00:28:53,640
Speaker 1: Yeah, great question. For most of the stuff that's not

628
00:28:53,760 --> 00:28:56,280
Speaker 1: at the center of the galaxy, we still can see it.

629
00:28:56,360 --> 00:28:59,280
Speaker 1: We can see through our spur to other spurs. We

630
00:28:59,280 --> 00:29:01,800
Speaker 1: can figure out where those stars are. But a lot

631
00:29:01,800 --> 00:29:04,080
Speaker 1: of it is obscured by the gas and the dust,

632
00:29:04,200 --> 00:29:06,800
Speaker 1: especially in the direction of the center of the Milky Way,

633
00:29:07,040 --> 00:29:09,640
Speaker 1: and so visible light just doesn't work. Like I get

634
00:29:09,640 --> 00:29:12,280
Speaker 1: a sense for how little we can see the center

635
00:29:12,320 --> 00:29:16,480
Speaker 1: of the galaxy. If you sent a trillion photons to

636
00:29:16,720 --> 00:29:19,200
Speaker 1: us from the center of the galaxy, one of them

637
00:29:19,320 --> 00:29:21,800
Speaker 1: would survive. So it's like a dipping by a factor

638
00:29:21,880 --> 00:29:24,840
Speaker 1: of a trillion from all of this gas and dust

639
00:29:25,200 --> 00:29:28,480
Speaker 1: in the visible spectrum. But there are other frequencies of

640
00:29:28,600 --> 00:29:30,960
Speaker 1: light that are better at getting through that gas and

641
00:29:31,080 --> 00:29:33,400
Speaker 1: dust that we can use to see what's going on

642
00:29:33,480 --> 00:29:34,600
Speaker 1: in the rest of the galaxy.

643
00:29:34,840 --> 00:29:38,440
Speaker 2: M Like, certain light waves don't get stopped by gas

644
00:29:38,440 --> 00:29:41,760
Speaker 2: and dust. Those atoms out there floating just ignore the light.

645
00:29:41,720 --> 00:29:44,600
Speaker 1: Right exactly. We just did an episode on transparency. We

646
00:29:44,720 --> 00:29:47,760
Speaker 1: talked all about how different frequencies of light interact with

647
00:29:47,840 --> 00:29:51,280
Speaker 1: matter differently. So visible light goes through our atmosphere, which

648
00:29:51,320 --> 00:29:54,360
Speaker 1: is why we can see stuff, but UV light is

649
00:29:54,480 --> 00:29:57,080
Speaker 1: often blocked by the stuff in our atmosphere, so the

650
00:29:57,080 --> 00:30:00,800
Speaker 1: atmosphere is partially opaque to UV light. Different frequencies of

651
00:30:00,880 --> 00:30:04,480
Speaker 1: light interact with objects differently. Some things are transparent in

652
00:30:04,520 --> 00:30:08,960
Speaker 1: some frequencies and opaque in other frequencies. And so cosmic dust,

653
00:30:08,960 --> 00:30:12,560
Speaker 1: which is basically just like little tiny rocks, tiny little

654
00:30:12,720 --> 00:30:15,920
Speaker 1: bits of old planets and the hearts of stars that

655
00:30:15,960 --> 00:30:18,680
Speaker 1: blew up and got spread out. Those things are good

656
00:30:18,680 --> 00:30:22,320
Speaker 1: at interacting with high frequency light because they're so small,

657
00:30:22,680 --> 00:30:26,320
Speaker 1: but low frequency light, radio waves and infrared, it's big

658
00:30:26,400 --> 00:30:29,400
Speaker 1: enough that it basically doesn't see them, just passes right

659
00:30:29,440 --> 00:30:29,920
Speaker 1: through them.

660
00:30:30,120 --> 00:30:32,240
Speaker 2: Big enough in the sense that like the atoms that

661
00:30:32,280 --> 00:30:34,560
Speaker 2: are floating out there can't do anything with that light, right.

662
00:30:34,680 --> 00:30:37,080
Speaker 1: Yeah, the general rule of thumb is if you're seeing

663
00:30:37,120 --> 00:30:39,960
Speaker 1: something in light, you can't really see stuff that's smaller

664
00:30:39,960 --> 00:30:42,880
Speaker 1: than the wavelength of light that you are using. And

665
00:30:42,960 --> 00:30:46,240
Speaker 1: so if you use very long wavelength light, it basically

666
00:30:46,280 --> 00:30:50,520
Speaker 1: ignores everything that's smaller than its wavelength. So long wavelength

667
00:30:50,600 --> 00:30:53,880
Speaker 1: light is really good at getting through clouds of tiny

668
00:30:53,960 --> 00:30:57,520
Speaker 1: little particles. So that's why radio waves and infrared can

669
00:30:57,560 --> 00:31:00,040
Speaker 1: get through this stuff, whereas UV light and visit a

670
00:31:00,280 --> 00:31:03,280
Speaker 1: light which has shorter wavelengths, can't really get through this dust.

671
00:31:04,240 --> 00:31:07,000
Speaker 2: It's literally like having X ray vision of the galaxy.

672
00:31:07,080 --> 00:31:08,600
Speaker 2: Like if you could see in the X ray yet

673
00:31:08,680 --> 00:31:10,600
Speaker 2: X ray glasses, you could see the center of the

674
00:31:10,600 --> 00:31:11,680
Speaker 2: galaxy more clearly.

675
00:31:11,840 --> 00:31:14,560
Speaker 1: And in general, that's why it's so powerful to have

676
00:31:14,880 --> 00:31:18,040
Speaker 1: telescopes that can see in different frequencies, because some parts

677
00:31:18,040 --> 00:31:20,560
Speaker 1: of the galaxy are like really bright in X rays

678
00:31:20,600 --> 00:31:22,239
Speaker 1: and dim in the visible, so you need X ray

679
00:31:22,280 --> 00:31:24,920
Speaker 1: telescopes to see them. Other parts of the galaxy you

680
00:31:24,920 --> 00:31:27,640
Speaker 1: can only see in radio and infrared because of this

681
00:31:27,760 --> 00:31:30,160
Speaker 1: reddening from the cosmic dust. So you got to have

682
00:31:30,200 --> 00:31:34,200
Speaker 1: those infrared telescopes. James Web for example, is an infrared telescope.

683
00:31:34,240 --> 00:31:36,360
Speaker 1: It's really good at looking at the center of the

684
00:31:36,400 --> 00:31:38,240
Speaker 1: galaxy and this kind of stuff.

685
00:31:38,320 --> 00:31:40,400
Speaker 2: All Right, I guess I see how you can see

686
00:31:40,440 --> 00:31:43,240
Speaker 2: the center of the galaxy using X ray vision. But

687
00:31:43,320 --> 00:31:44,960
Speaker 2: I guess my question is, like, how do you know

688
00:31:45,040 --> 00:31:47,760
Speaker 2: the structure of the Milky Way from the point of

689
00:31:47,800 --> 00:31:49,240
Speaker 2: view where we are now? Like, how do you not

690
00:31:49,440 --> 00:31:51,959
Speaker 2: has these arms? Can you actually see those arms from

691
00:31:52,000 --> 00:31:53,680
Speaker 2: this point of view? But then it all looks sort

692
00:31:53,680 --> 00:31:57,480
Speaker 2: of like a fuzzy streak, Like if you look at

693
00:31:57,480 --> 00:31:59,560
Speaker 2: a frisbee from the side, you can't tell what it

694
00:31:59,600 --> 00:32:01,120
Speaker 2: looks like from the side. Yeah.

695
00:32:01,160 --> 00:32:04,320
Speaker 1: A crucial thing are distance measurements. So you need to

696
00:32:04,320 --> 00:32:06,120
Speaker 1: know how far away things are. You look at an

697
00:32:06,160 --> 00:32:08,360
Speaker 1: individual star out in space, you want to know how

698
00:32:08,400 --> 00:32:10,880
Speaker 1: far away it is. That lets you build a three

699
00:32:11,040 --> 00:32:13,880
Speaker 1: D map of the galaxy. So rather than just having

700
00:32:13,960 --> 00:32:17,640
Speaker 1: everything like pasted on a celestial sphere and not knowing

701
00:32:17,680 --> 00:32:20,160
Speaker 1: where things actually are, if you can say this star

702
00:32:20,280 --> 00:32:22,440
Speaker 1: is really far away, this one is really close. It

703
00:32:22,520 --> 00:32:24,600
Speaker 1: lets you build a three D map of everything and

704
00:32:24,640 --> 00:32:27,040
Speaker 1: from that you can build up the structure. And so

705
00:32:27,160 --> 00:32:29,440
Speaker 1: to know the distance of these stars, we need things

706
00:32:29,520 --> 00:32:32,560
Speaker 1: like cephids and parallax and all sorts of other tricks

707
00:32:32,560 --> 00:32:34,840
Speaker 1: that we've talked about before to figure out how far

708
00:32:34,880 --> 00:32:37,480
Speaker 1: away each star is. And that's one of the things

709
00:32:37,480 --> 00:32:40,040
Speaker 1: this Guya satellite is really good at. It does parallax

710
00:32:40,080 --> 00:32:43,720
Speaker 1: on all these stars and understands their location and also

711
00:32:43,800 --> 00:32:46,760
Speaker 1: their velocity, which is super cool. So we built up

712
00:32:46,760 --> 00:32:48,800
Speaker 1: sort of a three D map of the galaxy, and

713
00:32:48,880 --> 00:32:51,800
Speaker 1: of course we have better information about the side of

714
00:32:51,800 --> 00:32:54,200
Speaker 1: the galaxy that we're in and the spur that we

715
00:32:54,240 --> 00:32:56,280
Speaker 1: are in, so it gets fuzzier as you get to

716
00:32:56,320 --> 00:32:58,760
Speaker 1: the other side of the galaxy. And just as an example,

717
00:32:58,960 --> 00:33:01,440
Speaker 1: almost all of the X planets that we discovered are

718
00:33:01,480 --> 00:33:03,400
Speaker 1: in a little spot on our side.

719
00:33:03,160 --> 00:33:03,920
Speaker 2: Of the galaxy.

720
00:33:04,240 --> 00:33:06,680
Speaker 1: We can't like do exoplanet research on the other side

721
00:33:06,680 --> 00:33:08,960
Speaker 1: of the galaxy because we can't like see through the

722
00:33:09,000 --> 00:33:11,560
Speaker 1: center of the galaxy to that other side as well.

723
00:33:11,720 --> 00:33:12,440
Speaker 2: So we know a.

724
00:33:12,320 --> 00:33:14,760
Speaker 1: Lot more about our neighborhood on our side of the

725
00:33:14,760 --> 00:33:16,200
Speaker 1: galaxy than the rest of it.

726
00:33:16,760 --> 00:33:18,920
Speaker 2: I see you sort of use stereovision to try to

727
00:33:18,920 --> 00:33:20,720
Speaker 2: get a three D view from our point of view.

728
00:33:20,720 --> 00:33:24,640
Speaker 2: But this three D idea, the parallax only works for

729
00:33:24,880 --> 00:33:27,160
Speaker 2: close by things, right, does it actually work to see

730
00:33:27,200 --> 00:33:29,600
Speaker 2: how far something is on the other side of the galaxy.

731
00:33:29,720 --> 00:33:32,440
Speaker 1: Parallax is most powerful for close by things, but we

732
00:33:32,480 --> 00:33:36,080
Speaker 1: have this distance ladders. We have parallax for close by stuff,

733
00:33:36,080 --> 00:33:38,840
Speaker 1: and then we have cephids the variable stars for more

734
00:33:38,840 --> 00:33:41,360
Speaker 1: distant things on the other side of the galaxy. These

735
00:33:41,360 --> 00:33:44,600
Speaker 1: are stars where their period of variability when they get

736
00:33:44,600 --> 00:33:47,200
Speaker 1: bright and dim and brightened dim is connected to their

737
00:33:47,320 --> 00:33:49,880
Speaker 1: true brightness. And so by noticing how they get bright

738
00:33:49,920 --> 00:33:52,360
Speaker 1: and dim and the period of that, we can figure

739
00:33:52,360 --> 00:33:54,560
Speaker 1: out how right they actually are, and therefore we can

740
00:33:54,600 --> 00:33:57,120
Speaker 1: tell how far away they are. So you can use

741
00:33:57,120 --> 00:33:59,600
Speaker 1: sephids to understand how far away things are in the

742
00:33:59,640 --> 00:34:01,160
Speaker 1: other side side of the galaxy.

743
00:34:01,320 --> 00:34:02,760
Speaker 2: Aren't those pretty rare? Though?

744
00:34:02,920 --> 00:34:05,400
Speaker 1: Those are pretty rare, But the galaxy is huge, so

745
00:34:05,560 --> 00:34:08,759
Speaker 1: we have found several thousand sephids I think more than

746
00:34:08,800 --> 00:34:11,319
Speaker 1: thirty three hundred last time I checked, But we still

747
00:34:11,320 --> 00:34:13,920
Speaker 1: have some of those, so we can use those together

748
00:34:14,040 --> 00:34:16,080
Speaker 1: with parallax to get a kind of a picture, but

749
00:34:16,120 --> 00:34:18,760
Speaker 1: it's not perfect, and it's especially bad in the direction

750
00:34:18,840 --> 00:34:21,240
Speaker 1: of the center of the galaxy because the center tends

751
00:34:21,239 --> 00:34:24,000
Speaker 1: to redden things because of the dust. Dust only lets

752
00:34:24,120 --> 00:34:27,120
Speaker 1: redder light through, lower frequency light through, and so we

753
00:34:27,160 --> 00:34:29,719
Speaker 1: don't always know, like always that actually a dimmer star

754
00:34:30,400 --> 00:34:33,200
Speaker 1: or is it just reddened by all the dust. So,

755
00:34:33,280 --> 00:34:35,000
Speaker 1: like one thing people argue about it is like how

756
00:34:35,040 --> 00:34:37,400
Speaker 1: far away is the center of the galaxy exactly? And

757
00:34:37,440 --> 00:34:40,000
Speaker 1: there's all these measurements, some of which disagree with each

758
00:34:40,040 --> 00:34:42,960
Speaker 1: other about exactly how far away it is. It's really

759
00:34:42,960 --> 00:34:45,239
Speaker 1: a challenge to measure the distance to the center of

760
00:34:45,280 --> 00:34:45,840
Speaker 1: the galaxy.

761
00:34:46,000 --> 00:34:47,560
Speaker 2: Right. That's kind of what I'm trying to get at,

762
00:34:47,640 --> 00:34:50,640
Speaker 2: which is that, you know, we see all these illustrations

763
00:34:50,680 --> 00:34:54,040
Speaker 2: of what the Milky Way looks like online and in books, like, hey,

764
00:34:54,080 --> 00:34:55,520
Speaker 2: this is what the milk Away looks like, but we

765
00:34:55,600 --> 00:34:58,880
Speaker 2: really don't know what the Milky Way looks like. And

766
00:34:58,920 --> 00:35:00,960
Speaker 2: I'm just kind of wondering, like, what does the picture

767
00:35:01,000 --> 00:35:03,279
Speaker 2: of what we actually know look like. Maybe we have

768
00:35:03,360 --> 00:35:07,360
Speaker 2: some sense of structure around us, but then for the

769
00:35:07,400 --> 00:35:09,600
Speaker 2: rest of the galaxy, like the other arms on the

770
00:35:09,640 --> 00:35:12,879
Speaker 2: other side, how many sephids, do we actually know are there?

771
00:35:13,040 --> 00:35:15,760
Speaker 2: And what is that the map of the data actually

772
00:35:15,760 --> 00:35:16,120
Speaker 2: looks like.

773
00:35:16,239 --> 00:35:18,279
Speaker 1: I think we do know roughly the shape of the

774
00:35:18,280 --> 00:35:20,759
Speaker 1: Milky Way. I mean, we know those other spurs and

775
00:35:20,800 --> 00:35:23,319
Speaker 1: the guy A satellite and the sephids do paint that

776
00:35:23,360 --> 00:35:26,399
Speaker 1: picture for us. It's definitely fuzzier on the other side

777
00:35:26,440 --> 00:35:28,919
Speaker 1: of the galaxy than it is here, and we don't

778
00:35:28,920 --> 00:35:31,200
Speaker 1: have like the crystal picture we'd love to have if

779
00:35:31,239 --> 00:35:33,160
Speaker 1: you were like out on top of the galaxy and

780
00:35:33,200 --> 00:35:35,360
Speaker 1: just took a picture from it. So it definitely limited

781
00:35:35,440 --> 00:35:37,120
Speaker 1: as we go to the other side of the galaxy.

782
00:35:37,239 --> 00:35:39,960
Speaker 1: But these illustrations you see about the shape of the galaxy,

783
00:35:40,080 --> 00:35:41,880
Speaker 1: those are pretty right on. I mean, we don't have

784
00:35:42,160 --> 00:35:45,160
Speaker 1: every single star in those arms on the other side

785
00:35:45,480 --> 00:35:47,640
Speaker 1: the way we do on our spur or even in

786
00:35:47,960 --> 00:35:50,960
Speaker 1: the neighboring spur, but we're pretty sure about the shape

787
00:35:50,960 --> 00:35:51,799
Speaker 1: of the Milky Way.

788
00:35:52,080 --> 00:35:54,280
Speaker 2: All right, let's get back to the center of the galaxy.

789
00:35:54,400 --> 00:36:09,160
Speaker 1: But first let's take a quick break. We're back and

790
00:36:09,200 --> 00:36:12,239
Speaker 1: we're thinking about how to actually see the center of

791
00:36:12,320 --> 00:36:16,040
Speaker 1: the galaxy. So there was recently a really cool image

792
00:36:16,040 --> 00:36:19,279
Speaker 1: of the center of the galaxy taken by a radio telescope.

793
00:36:19,760 --> 00:36:22,520
Speaker 1: This is an array of telescopes in South Africa. It's

794
00:36:22,520 --> 00:36:25,319
Speaker 1: called Meerkat, and radio is still the best way to

795
00:36:25,360 --> 00:36:27,520
Speaker 1: see the center of the galaxy because of course it's

796
00:36:27,520 --> 00:36:30,080
Speaker 1: the longest wave length, and so it gets through the

797
00:36:30,120 --> 00:36:32,280
Speaker 1: gas and the dust and it gives us this awesome

798
00:36:32,320 --> 00:36:35,319
Speaker 1: picture of what's going on. This like morphology, shows us

799
00:36:35,400 --> 00:36:38,200
Speaker 1: the shapes of stuff in the center of the galaxy,

800
00:36:38,640 --> 00:36:40,799
Speaker 1: as if we could like X ray through all that

801
00:36:40,920 --> 00:36:44,160
Speaker 1: gas and dust. So the Meerkat radio telescope is basically

802
00:36:44,239 --> 00:36:47,239
Speaker 1: an array eight by eight of these sixty four antennas

803
00:36:47,320 --> 00:36:51,400
Speaker 1: spread across five miles of desert in South Africa, and

804
00:36:51,440 --> 00:36:54,480
Speaker 1: they put out of paper recently with this incredible picture

805
00:36:54,760 --> 00:36:56,440
Speaker 1: of the center of the galaxy.

806
00:36:56,640 --> 00:36:59,200
Speaker 2: Now, now these are not telescopes like maybe we think

807
00:36:59,200 --> 00:37:01,239
Speaker 2: of when we see are the word toscode. They don't

808
00:37:01,239 --> 00:37:03,040
Speaker 2: have lenses that they don't look like it too. They

809
00:37:03,040 --> 00:37:06,840
Speaker 2: look more like giant dishes, right, like the kind you

810
00:37:06,840 --> 00:37:09,319
Speaker 2: see in the movie Contact. Yeah, that's right.

811
00:37:09,400 --> 00:37:12,640
Speaker 1: It's an array of dishes, and so each one looks

812
00:37:12,719 --> 00:37:14,640
Speaker 1: like a satellite dish. You might be using it to

813
00:37:14,640 --> 00:37:17,120
Speaker 1: broughout your favorite sports team on but you have an

814
00:37:17,239 --> 00:37:19,920
Speaker 1: array of them spread across the desert. What you'd love,

815
00:37:19,960 --> 00:37:22,000
Speaker 1: of course, is just to have like a five mile

816
00:37:22,120 --> 00:37:25,759
Speaker 1: wide dish to gather all of that information. You can't

817
00:37:25,760 --> 00:37:28,160
Speaker 1: afford to build that. But it's better to have sixty

818
00:37:28,160 --> 00:37:31,719
Speaker 1: four separate dishes that have greater distance between them than

819
00:37:31,800 --> 00:37:33,760
Speaker 1: to have one big dish that's.

820
00:37:33,560 --> 00:37:34,640
Speaker 2: In the end smaller.

821
00:37:35,040 --> 00:37:38,000
Speaker 1: You in effect have a larger aperture.

822
00:37:37,680 --> 00:37:40,319
Speaker 2: Sort of like having tapas for dinner instead of it

823
00:37:41,000 --> 00:37:42,760
Speaker 2: big dish.

824
00:37:42,960 --> 00:37:45,279
Speaker 1: That's right, And you can get more information by having

825
00:37:45,280 --> 00:37:47,040
Speaker 1: these dishes like further apart.

826
00:37:46,920 --> 00:37:49,040
Speaker 2: Like a sampler plate of appetize.

827
00:37:49,960 --> 00:37:53,000
Speaker 1: As the information washes across your array, you can tell

828
00:37:53,120 --> 00:37:55,880
Speaker 1: which direction it came from. You can do interferometry to

829
00:37:55,920 --> 00:37:58,799
Speaker 1: get all sorts of useful information. So it's almost as

830
00:37:58,840 --> 00:38:03,360
Speaker 1: good as having a single telescope that's like actually five

831
00:38:03,440 --> 00:38:06,240
Speaker 1: miles wide, so it doesn't look like a traditional telescope.

832
00:38:06,239 --> 00:38:08,560
Speaker 1: There's nobody like peering through a lens and seeing the

833
00:38:08,640 --> 00:38:11,399
Speaker 1: center of the galaxy. They get this data, which again

834
00:38:11,480 --> 00:38:14,359
Speaker 1: is not even visible light, it's radio waves, and they

835
00:38:14,400 --> 00:38:17,000
Speaker 1: process it and they convert it into something that you

836
00:38:17,000 --> 00:38:20,000
Speaker 1: can see with your eyes. And so there's this wavelength

837
00:38:20,080 --> 00:38:23,160
Speaker 1: shifting right, you would never see this image yourself. It

838
00:38:23,200 --> 00:38:25,719
Speaker 1: comes in light that your eyeballs can't see. But we

839
00:38:25,760 --> 00:38:28,239
Speaker 1: do all this computing. We crunch the numbers and we

840
00:38:28,320 --> 00:38:31,600
Speaker 1: figure out where are the bright sources of radio. So

841
00:38:31,840 --> 00:38:34,600
Speaker 1: if you google this image from meercap, what you're looking

842
00:38:34,680 --> 00:38:37,600
Speaker 1: at is where there are intense radio sources and where

843
00:38:37,640 --> 00:38:39,279
Speaker 1: there's less intense radio.

844
00:38:39,040 --> 00:38:41,560
Speaker 2: Sources, and it's sort of focused to the center of

845
00:38:41,600 --> 00:38:43,520
Speaker 2: the galaxy. That's kind of the idea, right, That's why

846
00:38:43,520 --> 00:38:45,279
Speaker 2: you having so far apart is that you can sort

847
00:38:45,280 --> 00:38:49,080
Speaker 2: of triangulate and be confident that what you're seeing is

848
00:38:49,120 --> 00:38:51,400
Speaker 2: coming from the center and it's not just some artifact

849
00:38:51,400 --> 00:38:52,480
Speaker 2: that's in between.

850
00:38:52,640 --> 00:38:54,120
Speaker 1: And you can see at the very heart of this

851
00:38:54,200 --> 00:38:57,239
Speaker 1: image is Sagittarius astar. We know this is a really

852
00:38:57,239 --> 00:38:59,279
Speaker 1: big black hole there, and we know it generates a

853
00:38:59,320 --> 00:39:02,920
Speaker 1: lot of radio waves from the gas that's swirling around it,

854
00:39:03,200 --> 00:39:05,319
Speaker 1: and it's the brightest thing in radio. So it's at

855
00:39:05,320 --> 00:39:08,239
Speaker 1: the very center. It's very small, it's very bright. So

856
00:39:08,239 --> 00:39:10,799
Speaker 1: that's super cool because it shows you, like, wow, the

857
00:39:10,840 --> 00:39:14,400
Speaker 1: center of the galaxy really does have this very intense core,

858
00:39:14,840 --> 00:39:16,920
Speaker 1: and then spread around it is the beginning of the

859
00:39:16,960 --> 00:39:17,840
Speaker 1: galactic disc.

860
00:39:18,560 --> 00:39:20,640
Speaker 2: No, the black hole is sucking stuff in, but the

861
00:39:20,680 --> 00:39:23,280
Speaker 2: stuff that's falling into it, that's the stuff that's really bright.

862
00:39:23,360 --> 00:39:23,759
Speaker 2: That's right.

863
00:39:23,760 --> 00:39:26,160
Speaker 1: We don't see anything from the black hole itself. Right,

864
00:39:26,200 --> 00:39:28,160
Speaker 1: the black hole is the black hole. We're not seeing

865
00:39:28,200 --> 00:39:31,560
Speaker 1: hawking radiation or anything. Black hole we think is totally black.

866
00:39:31,960 --> 00:39:34,359
Speaker 1: But the stuff that's swirling around it and falling in

867
00:39:34,719 --> 00:39:37,560
Speaker 1: that is accelerating and giving off radiation. We can only

868
00:39:37,560 --> 00:39:39,840
Speaker 1: see it in the radio because everything else is blocked.

869
00:39:40,040 --> 00:39:41,960
Speaker 2: Cool. So we have this picture from the center of

870
00:39:41,960 --> 00:39:44,399
Speaker 2: the galaxy. You can look it up. It's called meer

871
00:39:44,440 --> 00:39:45,719
Speaker 2: Cat And what do we learn from it?

872
00:39:45,760 --> 00:39:48,040
Speaker 1: So the black hole is no surprise, but there's a

873
00:39:48,040 --> 00:39:50,520
Speaker 1: bunch of other cool features. You can see these blobs

874
00:39:50,560 --> 00:39:53,040
Speaker 1: from the beginning of the galactic disc, and it's sort

875
00:39:53,040 --> 00:39:57,120
Speaker 1: of cool that it's tilted. They've plotted in these celestial coordinates,

876
00:39:57,120 --> 00:40:00,759
Speaker 1: which is declination versus right ascension, which is just sort

877
00:40:00,800 --> 00:40:02,520
Speaker 1: of like a grid around the Earth that uses the

878
00:40:02,560 --> 00:40:05,000
Speaker 1: north and the South poles, and so it's tilted pretty

879
00:40:05,040 --> 00:40:07,319
Speaker 1: hard in those angles, and it shows you, like the

880
00:40:07,360 --> 00:40:10,080
Speaker 1: angle of the Earth relative to the angle of the

881
00:40:10,160 --> 00:40:12,759
Speaker 1: disk of the galaxy. Right, the north pole of the

882
00:40:12,800 --> 00:40:15,240
Speaker 1: Earth is not aligned with the north pole of the galaxy,

883
00:40:15,280 --> 00:40:18,120
Speaker 1: like the equator is not aligned with the galactic disk.

884
00:40:18,160 --> 00:40:20,680
Speaker 1: It's actually quite tilted. So that's sort of cool. It

885
00:40:20,719 --> 00:40:23,279
Speaker 1: orients you, right, It shows you that, like, whoa, we're

886
00:40:23,320 --> 00:40:24,160
Speaker 1: kind of leaning.

887
00:40:23,920 --> 00:40:27,359
Speaker 2: Over, we're leaning into the galaxy. But I guess there

888
00:40:27,440 --> 00:40:29,120
Speaker 2: is there any reason to expect that they would be

889
00:40:29,120 --> 00:40:31,640
Speaker 2: aligned or it's is it kind of random?

890
00:40:31,760 --> 00:40:34,080
Speaker 1: It's kind of random. I mean, the Earth is kind

891
00:40:34,120 --> 00:40:36,840
Speaker 1: of aligned with the spin of the Sun and the

892
00:40:36,920 --> 00:40:38,840
Speaker 1: disk of the Solar system, though of course there's a

893
00:40:38,880 --> 00:40:42,040
Speaker 1: tilt there. But the spin of our Sun is not

894
00:40:42,120 --> 00:40:46,040
Speaker 1: necessarily aligned with the spin of the galaxy, right, because

895
00:40:46,080 --> 00:40:48,839
Speaker 1: all the stars basically have random directions. It just comes

896
00:40:48,880 --> 00:40:51,600
Speaker 1: from the spin of the blob of gas and dust

897
00:40:51,680 --> 00:40:54,280
Speaker 1: that formed our Solar system. But it just helps orient

898
00:40:54,320 --> 00:40:56,960
Speaker 1: you and show you that, like, our north pole is

899
00:40:56,960 --> 00:40:58,720
Speaker 1: not like the galactic north pole.

900
00:40:58,960 --> 00:41:02,279
Speaker 2: M Our north pole is not the Sun's north pole

901
00:41:02,400 --> 00:41:04,200
Speaker 2: you were saying. It just kind of gives us a

902
00:41:04,320 --> 00:41:06,000
Speaker 2: sense of which where we're actually going.

903
00:41:06,440 --> 00:41:08,799
Speaker 1: Yeah, And even though it makes no sense, it gives

904
00:41:08,840 --> 00:41:11,520
Speaker 1: me a little bit of vertigo because I feel like

905
00:41:11,560 --> 00:41:13,480
Speaker 1: I'm standing here on the Earth and I'm like, whoa,

906
00:41:13,600 --> 00:41:15,440
Speaker 1: I'm leaning over, and everybody in the center of the

907
00:41:15,440 --> 00:41:17,480
Speaker 1: galaxy looking at us is like, whoa, those guys are

908
00:41:17,520 --> 00:41:20,040
Speaker 1: leaning over. And I mean it makes no sense obviously,

909
00:41:20,360 --> 00:41:22,000
Speaker 1: but it sort of gives me this sense of vertigo.

910
00:41:22,160 --> 00:41:24,800
Speaker 2: Yeah. I mean, everyone knows South Pasadena is the true

911
00:41:24,840 --> 00:41:27,400
Speaker 2: north pole of the galaxy, and so I feel it

912
00:41:27,480 --> 00:41:28,279
Speaker 2: just fine.

913
00:41:28,000 --> 00:41:29,800
Speaker 1: Right, yeah, well that's the north pole of the podcast

914
00:41:29,880 --> 00:41:33,360
Speaker 1: universe also. But you also see these other really cool features.

915
00:41:33,480 --> 00:41:37,120
Speaker 1: Some of my favorite features are super nova remnants, So

916
00:41:37,160 --> 00:41:39,040
Speaker 1: a bunch of stars that used to be near the

917
00:41:39,080 --> 00:41:41,359
Speaker 1: center of the galaxy and then blew up. You can

918
00:41:41,400 --> 00:41:44,560
Speaker 1: see their clouds. You can see these like puffs from

919
00:41:44,600 --> 00:41:47,720
Speaker 1: the super nova that are left over from these stars

920
00:41:47,719 --> 00:41:48,560
Speaker 1: having exploded.

921
00:41:48,640 --> 00:41:49,680
Speaker 2: Where did those come from?

922
00:41:49,719 --> 00:41:52,400
Speaker 1: Those just came from stars that lived and burned and

923
00:41:52,440 --> 00:41:55,359
Speaker 1: then died. And then the other really fascinating thing are

924
00:41:55,400 --> 00:41:58,920
Speaker 1: these filaments above and below the disk of the galaxy.

925
00:41:59,080 --> 00:42:02,200
Speaker 1: Are these shooting lines sort of like the galaxy has

926
00:42:02,200 --> 00:42:05,960
Speaker 1: these hairs or something, and they stretch for like hundreds

927
00:42:06,000 --> 00:42:07,080
Speaker 1: of light years.

928
00:42:07,080 --> 00:42:09,759
Speaker 2: You mean, like sort of like geysers or just as

929
00:42:09,920 --> 00:42:11,320
Speaker 2: structures of stars.

930
00:42:11,040 --> 00:42:13,799
Speaker 1: Well, we don't really understand what they are exactly. But

931
00:42:13,840 --> 00:42:15,920
Speaker 1: they don't just shoot up and down from the black hole.

932
00:42:15,920 --> 00:42:18,240
Speaker 1: They're shooting like up and down from the whole disc.

933
00:42:18,760 --> 00:42:21,080
Speaker 1: So in this picture you could see like dozens of

934
00:42:21,120 --> 00:42:23,600
Speaker 1: these things. There are these streaks up and down above

935
00:42:23,719 --> 00:42:27,560
Speaker 1: and below the disc, these huge filaments, And we've known

936
00:42:27,600 --> 00:42:29,600
Speaker 1: about these for a few decades that we've only ever

937
00:42:29,680 --> 00:42:31,920
Speaker 1: seen a few of them. People think that they're like

938
00:42:32,040 --> 00:42:36,799
Speaker 1: maybe these weird magnetized tubes of gas that funnel high

939
00:42:37,000 --> 00:42:40,120
Speaker 1: energy particles and then those particles are emitting in the

940
00:42:40,239 --> 00:42:43,400
Speaker 1: radio because they're getting accelerated by the magnetic field. But

941
00:42:43,440 --> 00:42:46,240
Speaker 1: nobody has any theory for like why these things exist.

942
00:42:46,320 --> 00:42:48,239
Speaker 1: When we found them a few decades ago, it was

943
00:42:48,280 --> 00:42:51,440
Speaker 1: a pretty big surprise to see these like hairs sticking

944
00:42:51,520 --> 00:42:54,200
Speaker 1: up and down from the top and bottom of the galaxy.

945
00:42:54,800 --> 00:42:58,719
Speaker 2: M just sort of like tornadoes. Kind of sounds like, yeah.

946
00:42:58,480 --> 00:43:01,640
Speaker 1: Exactly, they're like magnetic parts article tornadoes. And so there's

947
00:43:01,640 --> 00:43:04,040
Speaker 1: some clue there about like the turbulence at the center

948
00:43:04,080 --> 00:43:07,279
Speaker 1: of the galaxy. Maybe the stars are interacting somehow with

949
00:43:07,320 --> 00:43:10,960
Speaker 1: their magnetic fields and the larger galactic magnetic field. We

950
00:43:11,000 --> 00:43:13,040
Speaker 1: don't really know. But one thing that's really cool about

951
00:43:13,080 --> 00:43:15,279
Speaker 1: this picture is that it's the first time we have

952
00:43:15,440 --> 00:43:18,319
Speaker 1: like enough of these things to start to do like statistics,

953
00:43:18,360 --> 00:43:20,719
Speaker 1: to say like how often are they here or are

954
00:43:20,719 --> 00:43:23,759
Speaker 1: they connected to stars or whatever. So it's the first

955
00:43:23,760 --> 00:43:26,600
Speaker 1: picture that really gives us enough detail to start to

956
00:43:26,719 --> 00:43:29,840
Speaker 1: understand the crazy dynamics at the heart of the galaxy.

957
00:43:30,120 --> 00:43:33,920
Speaker 2: M And I guess that's important because you know, understanding

958
00:43:34,000 --> 00:43:36,840
Speaker 2: what's happening in the center of the galaxy tells us

959
00:43:36,880 --> 00:43:39,520
Speaker 2: a bit about how galaxies form right and where they're

960
00:43:39,520 --> 00:43:40,440
Speaker 2: going exactly.

961
00:43:40,800 --> 00:43:43,200
Speaker 1: And we also know that the galaxy center is very

962
00:43:43,239 --> 00:43:45,319
Speaker 1: different from the rest of the galaxy. Like we can

963
00:43:45,400 --> 00:43:48,360
Speaker 1: think about star formation out here in the suburbs and

964
00:43:48,480 --> 00:43:50,880
Speaker 1: understand it, but star formation in the center of the

965
00:43:50,920 --> 00:43:53,960
Speaker 1: galaxy is very, very different because the conditions are different.

966
00:43:54,280 --> 00:43:56,960
Speaker 1: And anytime you have different conditions, you have an opportunity

967
00:43:57,000 --> 00:43:59,959
Speaker 1: to learn something new because maybe your theory for star

968
00:44:00,120 --> 00:44:03,560
Speaker 1: formation works, but maybe it doesn't right and maybe there's

969
00:44:03,560 --> 00:44:07,120
Speaker 1: something else happening. For example, they recently discovered a blob

970
00:44:07,200 --> 00:44:10,759
Speaker 1: of like one hundred very new stars very close to

971
00:44:10,840 --> 00:44:13,160
Speaker 1: the center of the galaxy. And again we don't think

972
00:44:13,200 --> 00:44:15,040
Speaker 1: that the center of the galaxy is a good place

973
00:44:15,120 --> 00:44:18,760
Speaker 1: to form stars because of all the crazy intense radiation,

974
00:44:19,239 --> 00:44:21,880
Speaker 1: the heats up the gas, and yet they found this

975
00:44:22,000 --> 00:44:25,720
Speaker 1: blob of like one hundred very massive, very short lived stars.

976
00:44:26,040 --> 00:44:28,879
Speaker 1: They don't understand how those formed. Something else is going

977
00:44:28,920 --> 00:44:32,120
Speaker 1: on that we don't understand. People think maybe there are

978
00:44:32,160 --> 00:44:35,360
Speaker 1: like these clusters of metals that pull gas together, but

979
00:44:35,480 --> 00:44:38,600
Speaker 1: nobody can understand why these stars exist. They call it

980
00:44:38,640 --> 00:44:40,080
Speaker 1: the paradox of youth.

981
00:44:40,280 --> 00:44:42,320
Speaker 2: And how do we see these stars? Do they emit

982
00:44:42,360 --> 00:44:43,359
Speaker 2: a lot of radio ways too.

983
00:44:43,600 --> 00:44:45,799
Speaker 1: Stars actually don't emit in the radio, so we can't

984
00:44:45,800 --> 00:44:48,640
Speaker 1: see them that way. But stars do emit in the infrared,

985
00:44:49,200 --> 00:44:52,040
Speaker 1: and so infrared telescopes can see into the center of

986
00:44:52,080 --> 00:44:54,640
Speaker 1: the galaxy, things like James Web. That's how, for example,

987
00:44:54,640 --> 00:44:57,000
Speaker 1: we can follow these stars that orbit very close to

988
00:44:57,040 --> 00:44:59,200
Speaker 1: the black hole. We can't see their visible light, it's

989
00:44:59,200 --> 00:45:01,719
Speaker 1: blocked by all that, but we can see them in

990
00:45:01,760 --> 00:45:02,480
Speaker 1: the infrared.

991
00:45:02,760 --> 00:45:04,440
Speaker 2: So mean, it's just sort of like a pocket of

992
00:45:04,560 --> 00:45:08,160
Speaker 2: inactivity that maybe that you have in these stars.

993
00:45:08,280 --> 00:45:10,160
Speaker 1: It could be, but there's a lot of stuff to

994
00:45:10,239 --> 00:45:12,400
Speaker 1: learn about what's going on in the center of the galaxy.

995
00:45:12,480 --> 00:45:14,200
Speaker 1: We'd also really like to understand the center of the

996
00:45:14,200 --> 00:45:16,880
Speaker 1: galaxy because it's where most of the dark matter is.

997
00:45:17,040 --> 00:45:19,719
Speaker 1: Dark matter is actually most of the mass of the galaxy.

998
00:45:19,960 --> 00:45:23,480
Speaker 1: Eighty or ninety percent of masses of galaxies are in

999
00:45:23,640 --> 00:45:26,360
Speaker 1: dark matter, and a lot of that is clustered towards

1000
00:45:26,440 --> 00:45:28,799
Speaker 1: the center. So people who want to understand, like what

1001
00:45:29,080 --> 00:45:32,280
Speaker 1: is the dark matter have all pointed their telescopes towards

1002
00:45:32,280 --> 00:45:34,279
Speaker 1: the center of the galaxy to see if they can

1003
00:45:34,480 --> 00:45:38,640
Speaker 1: observe dark matter doing something weird, like smashing into itself

1004
00:45:38,680 --> 00:45:41,440
Speaker 1: and giving off flashes of light that we might be

1005
00:45:41,520 --> 00:45:42,400
Speaker 1: able to detect.

1006
00:45:42,480 --> 00:45:44,319
Speaker 2: We don't know what it is what dark matter is,

1007
00:45:44,360 --> 00:45:46,400
Speaker 2: but we know there's a higher density of it in

1008
00:45:46,440 --> 00:45:49,440
Speaker 2: the center of the galaxy. Even though we can't actually see.

1009
00:45:49,280 --> 00:45:51,600
Speaker 1: It exactly, we know there's more of it in the

1010
00:45:51,640 --> 00:45:54,000
Speaker 1: center of the galaxy. Just by I understanding the velocity

1011
00:45:54,000 --> 00:45:56,279
Speaker 1: of stars how they swirl around in the galaxy, it

1012
00:45:56,320 --> 00:45:58,760
Speaker 1: gives us like a mass profile. It tells us where

1013
00:45:58,800 --> 00:46:01,200
Speaker 1: the mass in the galaxy is is. Because it's showing

1014
00:46:01,280 --> 00:46:03,839
Speaker 1: us where the gravity is. We could figure that out

1015
00:46:03,840 --> 00:46:06,640
Speaker 1: by how fast stars are rotating a different radii, and

1016
00:46:06,680 --> 00:46:08,239
Speaker 1: so we know there's a lot of dark matter in

1017
00:46:08,280 --> 00:46:10,560
Speaker 1: the center of the galaxy, so people have pointed special

1018
00:46:10,600 --> 00:46:12,719
Speaker 1: telescopes at the center of the galaxy to try to

1019
00:46:12,719 --> 00:46:16,680
Speaker 1: pick up signatures from that dark matter. And about five

1020
00:46:16,719 --> 00:46:19,680
Speaker 1: years ago, actually people saw these weird bumps, these very

1021
00:46:19,760 --> 00:46:22,680
Speaker 1: high energy gamma rays coming from the center of the

1022
00:46:22,719 --> 00:46:25,399
Speaker 1: galaxy that had to be super bright to get through

1023
00:46:25,400 --> 00:46:27,400
Speaker 1: all the gas and dust, but still they were making

1024
00:46:27,440 --> 00:46:29,839
Speaker 1: it to Earth and people were wondering, like, is this

1025
00:46:29,920 --> 00:46:32,919
Speaker 1: a sign of dark matter or is there something else

1026
00:46:32,960 --> 00:46:34,879
Speaker 1: going on at the center of the galaxy. It's hard

1027
00:46:34,880 --> 00:46:36,600
Speaker 1: to know if it's dark matter if you're not sure

1028
00:46:36,640 --> 00:46:39,239
Speaker 1: what else could be emitting radiation to the center of

1029
00:46:39,280 --> 00:46:42,440
Speaker 1: the galaxy. So basically understanding what's at the center of

1030
00:46:42,480 --> 00:46:45,200
Speaker 1: the galaxy gives us an opportunity to learn a lot

1031
00:46:45,239 --> 00:46:47,279
Speaker 1: more different kinds of physics, to do all sorts of

1032
00:46:47,320 --> 00:46:50,320
Speaker 1: tests to look for dark matter, to understand star formation.

1033
00:46:50,600 --> 00:46:52,960
Speaker 1: It's just like a really cool laboratory because the conditions

1034
00:46:53,000 --> 00:46:54,840
Speaker 1: are so weird and different and intense.

1035
00:46:55,080 --> 00:46:58,399
Speaker 2: And I guess it's the closest galactic center to us, right,

1036
00:46:58,440 --> 00:47:00,920
Speaker 2: I mean, we can see other galaxies, but maybe we

1037
00:47:00,960 --> 00:47:03,359
Speaker 2: can't see it as much detail as we can the

1038
00:47:03,400 --> 00:47:04,520
Speaker 2: center of our galaxy.

1039
00:47:04,600 --> 00:47:07,120
Speaker 1: Yeah, it's both good and bad. It's very close, as

1040
00:47:07,160 --> 00:47:10,399
Speaker 1: you say, so we can trace out stellar motion near

1041
00:47:10,480 --> 00:47:13,760
Speaker 1: the black hole, but also it's obscured by gas and dust.

1042
00:47:14,080 --> 00:47:15,880
Speaker 1: So in some ways we can see the centers of

1043
00:47:15,920 --> 00:47:19,680
Speaker 1: other galaxies more clearly, even though they're further away, because

1044
00:47:19,719 --> 00:47:23,040
Speaker 1: we don't have to look through their galactic disk. So

1045
00:47:23,120 --> 00:47:26,440
Speaker 1: it's both studying our galactic center and other galaxies. Galactic

1046
00:47:26,480 --> 00:47:28,280
Speaker 1: centers can teach us different kind of things.

1047
00:47:28,360 --> 00:47:30,600
Speaker 2: All right, Well, then, I guess maybe to summarize, what

1048
00:47:30,640 --> 00:47:32,520
Speaker 2: are some of the big questions we have about the

1049
00:47:32,560 --> 00:47:33,440
Speaker 2: center of the galaxy.

1050
00:47:33,560 --> 00:47:35,360
Speaker 1: So we don't understand a lot about the center of

1051
00:47:35,400 --> 00:47:37,239
Speaker 1: the galaxy, like what is in there? Are there a

1052
00:47:37,280 --> 00:47:40,200
Speaker 1: bunch of pulsars giving us weird blips and bleachs that

1053
00:47:40,280 --> 00:47:43,600
Speaker 1: might be dark matter? We don't understand, like why is

1054
00:47:43,640 --> 00:47:45,719
Speaker 1: there a bar in the center of the galaxy. Why

1055
00:47:45,760 --> 00:47:48,880
Speaker 1: isn't it just like a blob with arms. Some galaxies

1056
00:47:48,920 --> 00:47:51,920
Speaker 1: have bars, other galaxies don't have bars. We don't really

1057
00:47:51,960 --> 00:47:55,080
Speaker 1: understand like how that forms. We don't know if stars

1058
00:47:55,120 --> 00:47:57,239
Speaker 1: are still being made in the center of the galaxy,

1059
00:47:57,560 --> 00:48:00,000
Speaker 1: And that's something We really like to understand how star

1060
00:48:00,160 --> 00:48:03,799
Speaker 1: formation happens, why it stops. We don't understand these filaments,

1061
00:48:03,960 --> 00:48:07,799
Speaker 1: these weird magnetic particle tornadoes, what they mean, what they

1062
00:48:07,840 --> 00:48:10,400
Speaker 1: tell us about the magnetic fields of the stars, If

1063
00:48:10,400 --> 00:48:12,719
Speaker 1: there are super novas down there that are driving it.

1064
00:48:12,719 --> 00:48:14,600
Speaker 1: It's basically a big cloud of mystery.

1065
00:48:14,680 --> 00:48:16,560
Speaker 2: Yeah, and you forgot the biggest question of them all.

1066
00:48:16,840 --> 00:48:20,120
Speaker 2: Is the center of the galaxy bait? Or is it

1067
00:48:20,160 --> 00:48:21,160
Speaker 2: kind of a spicy green?

1068
00:48:21,280 --> 00:48:23,120
Speaker 1: How late do the dance club stay open in the

1069
00:48:23,120 --> 00:48:24,080
Speaker 1: center of the galaxy?

1070
00:48:24,239 --> 00:48:26,600
Speaker 2: Yeah? How big are the parking lots that you can

1071
00:48:26,640 --> 00:48:30,080
Speaker 2: get lost in down there? Are there good food trucks

1072
00:48:30,080 --> 00:48:32,200
Speaker 2: at two am? All right? Well, the next time you

1073
00:48:32,200 --> 00:48:34,480
Speaker 2: look up at the night sky, think about where you

1074
00:48:34,520 --> 00:48:37,240
Speaker 2: are in the galaxy and which way is it tilted?

1075
00:48:37,360 --> 00:48:39,600
Speaker 2: And where are all the exciting things happening in the

1076
00:48:39,640 --> 00:48:42,239
Speaker 2: milky Way? Is it near you? Or is it all

1077
00:48:42,280 --> 00:48:43,480
Speaker 2: happening downtown?

1078
00:48:43,600 --> 00:48:45,680
Speaker 1: And when you think about the broader context, try not

1079
00:48:45,760 --> 00:48:48,399
Speaker 1: to fall over from vertigo when you realize that we're

1080
00:48:48,480 --> 00:48:51,480
Speaker 1: tilted relative to the Sun. Who's tilted relatives to the galaxy?

1081
00:48:51,560 --> 00:48:55,640
Speaker 1: Who's just one of billions of galaxies floating out in space.

1082
00:48:55,960 --> 00:48:59,040
Speaker 2: He'pe you enjoyed that. Thanks for joining us, see you

1083
00:48:59,080 --> 00:48:59,480
Speaker 2: next time.

1084
00:49:07,360 --> 00:49:10,160
Speaker 1: Thanks for listening, and remember that Daniel and Jorge Explain

1085
00:49:10,239 --> 00:49:14,239
Speaker 1: the Universe is a production of iHeartRadio. For more podcasts

1086
00:49:14,239 --> 00:49:18,880
Speaker 1: from iHeartRadio, visit the iHeartRadio app, Apple Podcasts, or wherever

1087
00:49:18,960 --> 00:49:20,680
Speaker 1: you listen to your favorite shows.