1
00:00:08,560 --> 00:00:11,920
Speaker 1: Hey, or hey, do you like your bananas really really fresh?

2
00:00:12,280 --> 00:00:13,800
Speaker 1: Or like gently decayed?

3
00:00:14,520 --> 00:00:15,040
Speaker 2: Decayded?

4
00:00:15,440 --> 00:00:18,520
Speaker 1: What do you mean, like a rotten You know, bananas

5
00:00:18,520 --> 00:00:21,799
Speaker 1: are on the spectrum from like crunchy and green to

6
00:00:22,120 --> 00:00:25,040
Speaker 1: black and mushy, and everybody likes them differently. Where do

7
00:00:25,120 --> 00:00:26,360
Speaker 1: you sit on that spectrum?

8
00:00:26,440 --> 00:00:26,680
Speaker 3: Mmm?

9
00:00:27,200 --> 00:00:29,680
Speaker 2: I like him yellow but with a little bit of

10
00:00:29,720 --> 00:00:30,560
Speaker 2: a speckle to them.

11
00:00:30,720 --> 00:00:32,680
Speaker 1: Mmmm, so slightly decayed.

12
00:00:33,080 --> 00:00:35,680
Speaker 2: Slightly decayed but only a little bit. But you know,

13
00:00:36,120 --> 00:00:39,320
Speaker 2: I'm flexible. It depends on the how desperate I am

14
00:00:39,360 --> 00:00:40,200
Speaker 2: for banana and.

15
00:00:40,080 --> 00:00:41,959
Speaker 1: How desperate you are to keep from decaying.

16
00:00:42,120 --> 00:00:44,200
Speaker 2: What do you mean the bananas help you live.

17
00:00:44,120 --> 00:00:46,800
Speaker 1: Longer, probably longer than chocolate.

18
00:01:02,040 --> 00:01:05,560
Speaker 2: Hi am Porgemake Cartoonists, an author of Oliver's Great Big Universe.

19
00:01:05,800 --> 00:01:08,600
Speaker 1: Hey, I'm Daniel. I'm a particle physicist and a professor

20
00:01:08,640 --> 00:01:11,720
Speaker 1: at U See or Irvine, and I honestly think bananas

21
00:01:11,720 --> 00:01:13,039
Speaker 1: and chocolate don't mix.

22
00:01:13,360 --> 00:01:15,119
Speaker 2: You've never had it together before?

23
00:01:15,520 --> 00:01:18,480
Speaker 1: Oh no, I've tried them. It's just not a good combination.

24
00:01:18,680 --> 00:01:20,080
Speaker 1: The texture just clashes.

25
00:01:20,560 --> 00:01:20,840
Speaker 3: Hmm.

26
00:01:21,280 --> 00:01:23,280
Speaker 2: I wonder if you had the right way, like on

27
00:01:23,319 --> 00:01:25,560
Speaker 2: a fondue. Have you had it on a fondue? Then

28
00:01:25,600 --> 00:01:29,120
Speaker 2: they're both kind of soft and uh and delicious.

29
00:01:30,880 --> 00:01:33,560
Speaker 1: Yeah, but the bananas still got that squishiness to it,

30
00:01:33,640 --> 00:01:37,080
Speaker 1: you know, where the chocolate is like smooth and luxurious.

31
00:01:37,319 --> 00:01:39,600
Speaker 2: M Do you like anything with your chocolate or are

32
00:01:39,640 --> 00:01:40,600
Speaker 2: you a chocolate purist?

33
00:01:41,640 --> 00:01:44,679
Speaker 1: No, Pretzels and chocolate's good. Bread and chocolate a good.

34
00:01:44,760 --> 00:01:47,800
Speaker 1: Some fruits with chocolate, like a raspberry with chocolate, it's good.

35
00:01:47,880 --> 00:01:52,040
Speaker 1: Cherries and chocolate. Blueberries and chocolate. Bananas just doesn't fit. It.

36
00:01:52,080 --> 00:01:53,720
Speaker 2: Sounds like you've done a lot of experimenting.

37
00:01:53,880 --> 00:01:56,080
Speaker 1: I like to think of myself as very thorough.

38
00:01:58,160 --> 00:02:03,720
Speaker 2: Thorough in your chocolate comes. But how thur are you though?

39
00:02:04,080 --> 00:02:05,960
Speaker 2: Have you tried chocolate covered sardines?

40
00:02:07,960 --> 00:02:10,560
Speaker 1: You know, sometimes you just want to explore, and sometimes

41
00:02:10,600 --> 00:02:13,440
Speaker 1: you want to be guided by the theory, And the

42
00:02:13,440 --> 00:02:16,440
Speaker 1: theory tells me chocolate sardines are disgusting.

43
00:02:17,280 --> 00:02:19,400
Speaker 2: Chocolate covered broccoli perhaps.

44
00:02:19,560 --> 00:02:20,680
Speaker 1: Chocolate covered garbage.

45
00:02:20,760 --> 00:02:24,760
Speaker 2: Yeah, did you just called broccoli garbage?

46
00:02:25,200 --> 00:02:27,840
Speaker 1: No, but I think the combination of chocolate and broccoli

47
00:02:27,880 --> 00:02:30,640
Speaker 1: is garbage in theory. In theory, I could be.

48
00:02:30,680 --> 00:02:32,800
Speaker 2: I don't know for sure. Yeah, you could be wrong.

49
00:02:32,919 --> 00:02:36,440
Speaker 1: Somebody out there tell me about your savory chocolate exploration.

50
00:02:36,240 --> 00:02:37,960
Speaker 2: That's right, and then write a paper about it, and

51
00:02:38,000 --> 00:02:39,440
Speaker 2: then maybe Daniel will believe you.

52
00:02:39,600 --> 00:02:41,359
Speaker 1: Yeah, I'll even cite your paper in.

53
00:02:41,360 --> 00:02:46,160
Speaker 2: Your own paper. Jour chocolate cover pretzels or about chocolate

54
00:02:46,200 --> 00:02:47,000
Speaker 2: covered sardines.

55
00:02:47,080 --> 00:02:50,360
Speaker 1: Yes, exactly, there's an academic field for everything.

56
00:02:50,480 --> 00:02:52,959
Speaker 2: But anyways, welcome to our podcast, Daniel and Jorge Explain

57
00:02:53,040 --> 00:02:55,680
Speaker 2: the Universe, a production of iHeartRadio, where we.

58
00:02:55,600 --> 00:02:59,040
Speaker 1: Don't just talk about chocolate or bananas or chocolate and bananas.

59
00:02:59,120 --> 00:03:02,560
Speaker 1: We talk about big questions about the universe, things that

60
00:03:02,680 --> 00:03:05,640
Speaker 1: actually matter, things that make you go hmm, I wish

61
00:03:05,639 --> 00:03:08,920
Speaker 1: I knew the answer to that question, or my life

62
00:03:08,919 --> 00:03:11,920
Speaker 1: would be different if I knew the answer to this question.

63
00:03:12,280 --> 00:03:14,280
Speaker 1: Those are the kind of questions we dig into on

64
00:03:14,320 --> 00:03:16,400
Speaker 1: the podcast. How big is the universe? Where did it

65
00:03:16,400 --> 00:03:18,560
Speaker 1: all come from? How does it all work? And we

66
00:03:18,600 --> 00:03:20,600
Speaker 1: want to answer not just the questions that are in

67
00:03:20,639 --> 00:03:24,560
Speaker 1: the minds of professional scientists, but your questions, the ones

68
00:03:24,600 --> 00:03:27,000
Speaker 1: that you struggle with when you're trying to make sense

69
00:03:27,080 --> 00:03:29,320
Speaker 1: of the universe, or the ones that keep you up

70
00:03:29,400 --> 00:03:32,280
Speaker 1: at night. So send us your questions to Questions at

71
00:03:32,360 --> 00:03:34,600
Speaker 1: Daniel and Jorge dot com. You'll get an.

72
00:03:34,480 --> 00:03:37,000
Speaker 2: Answer that's right. We'd like to address all kinds of questions,

73
00:03:37,000 --> 00:03:39,000
Speaker 2: the kind that make you think that the universe is

74
00:03:39,040 --> 00:03:42,640
Speaker 2: amazing and sometimes a little bit bananas, those amazing facts

75
00:03:42,680 --> 00:03:45,600
Speaker 2: about the universe that make the cosmos such a slippery

76
00:03:45,600 --> 00:03:49,119
Speaker 2: subject to study, but at the same time so darn appealing.

77
00:03:51,520 --> 00:03:55,480
Speaker 1: What seems to continuously amaze listeners is that I'm promising

78
00:03:55,640 --> 00:03:57,960
Speaker 1: on air to answer all of their questions, and then

79
00:03:58,000 --> 00:04:00,280
Speaker 1: I can email from somebody and they're amazed that I

80
00:04:00,320 --> 00:04:02,600
Speaker 1: actually write them back. I've got an email from a

81
00:04:02,640 --> 00:04:04,840
Speaker 1: listener this morning saying, wow, you really will do right

82
00:04:04,880 --> 00:04:07,360
Speaker 1: back to all of us. It's like, yes, call my bluff,

83
00:04:07,440 --> 00:04:09,640
Speaker 1: write to me with your questions. I really do want

84
00:04:09,680 --> 00:04:10,280
Speaker 1: to answer them.

85
00:04:10,360 --> 00:04:11,440
Speaker 2: Wellhy do you think they're surprised?

86
00:04:11,520 --> 00:04:13,680
Speaker 1: I think if there's a lot of science communicators out

87
00:04:13,720 --> 00:04:16,520
Speaker 1: there that don't respond to their emails and that publicly

88
00:04:16,560 --> 00:04:19,880
Speaker 1: complain about how many emails they get and are negative

89
00:04:19,880 --> 00:04:21,560
Speaker 1: and stand offish about it, and yeah, I take the

90
00:04:21,600 --> 00:04:24,479
Speaker 1: opposite approach, and so maybe that's surprising to people. I

91
00:04:24,640 --> 00:04:26,240
Speaker 1: am a busy guy. Of course, I got lots of

92
00:04:26,240 --> 00:04:28,359
Speaker 1: things going on. But to me, this is a real joy.

93
00:04:28,480 --> 00:04:30,360
Speaker 1: I don't want this podcast to just be a one

94
00:04:30,360 --> 00:04:32,400
Speaker 1: direction a lecture. I want it to be a conversation

95
00:04:32,480 --> 00:04:35,280
Speaker 1: with everybody out there who's excited about these things, who

96
00:04:35,360 --> 00:04:38,360
Speaker 1: doesn't have a friendly neighborhood physicist, They can ask these

97
00:04:38,440 --> 00:04:41,480
Speaker 1: questions too, So yeah, send us your questions, engage with us,

98
00:04:41,560 --> 00:04:42,360
Speaker 1: have a conversation.

99
00:04:43,080 --> 00:04:46,919
Speaker 2: Do you know any friendly neighborhood physicists for friendly physicists,

100
00:04:47,800 --> 00:04:52,080
Speaker 2: I think you know one, yeah, But anyways, we do

101
00:04:52,240 --> 00:04:54,599
Speaker 2: like to answer listener questions here and sometimes we'd like

102
00:04:54,640 --> 00:04:57,440
Speaker 2: to answer them here on the podcast, live or at

103
00:04:57,560 --> 00:04:59,120
Speaker 2: least pre recorded on the.

104
00:04:59,040 --> 00:05:01,680
Speaker 1: Internet, live and heavily edited.

105
00:05:03,040 --> 00:05:06,719
Speaker 2: Are we heavily edited? I didn't know that how heavily edited?

106
00:05:06,760 --> 00:05:07,040
Speaker 4: Are we?

107
00:05:07,120 --> 00:05:10,159
Speaker 2: Can I just say anything and someone's gonna censor me.

108
00:05:11,160 --> 00:05:13,640
Speaker 1: You should check out our behind the scenes episode where

109
00:05:13,680 --> 00:05:15,560
Speaker 1: we talked to Corey about how much he cuts and

110
00:05:15,560 --> 00:05:17,760
Speaker 1: how much he keeps. Mostly it all ends up on

111
00:05:17,800 --> 00:05:19,560
Speaker 1: the air, but sometimes, you know, we back up and

112
00:05:19,600 --> 00:05:20,680
Speaker 1: say things another way.

113
00:05:20,960 --> 00:05:22,840
Speaker 2: But we do like to answer questions answer to the

114
00:05:22,960 --> 00:05:32,080
Speaker 2: on the podcast. We'll be tackling listener questions number sixty five.

115
00:05:32,480 --> 00:05:35,680
Speaker 2: We're getting four closer to one number. We might have

116
00:05:35,680 --> 00:05:39,560
Speaker 2: to skip. Daniel, Well, we have three awesome questions here

117
00:05:39,560 --> 00:05:44,039
Speaker 2: today from listeners. We have questions about banana radiation, the

118
00:05:44,160 --> 00:05:48,400
Speaker 2: half life of tiny particles, and how fast things spin

119
00:05:48,680 --> 00:05:51,480
Speaker 2: around a black hole. I guess whether or not they're

120
00:05:51,520 --> 00:05:52,240
Speaker 2: bananas or not.

121
00:05:53,040 --> 00:05:54,880
Speaker 1: Whether that makes them go bananas?

122
00:05:55,160 --> 00:05:56,520
Speaker 2: What if they're half bananas?

123
00:05:59,240 --> 00:06:00,880
Speaker 1: You'll have to ask that question and find out.

124
00:06:02,480 --> 00:06:04,320
Speaker 2: All right, well, let's get right down to it. Our

125
00:06:04,360 --> 00:06:08,080
Speaker 2: first question comes from Samia, who hails from Morocco.

126
00:06:08,240 --> 00:06:11,480
Speaker 5: Hi Daniel Hi hot Hay, So, I have been pondering

127
00:06:11,560 --> 00:06:16,040
Speaker 5: something lately. How do scientists define the half life of nukelids?

128
00:06:16,320 --> 00:06:20,800
Speaker 5: I always assumed it was determined experimentally, but then I

129
00:06:20,920 --> 00:06:24,200
Speaker 5: stumbled upon those massive numbers in billions of years. An

130
00:06:24,200 --> 00:06:30,240
Speaker 5: example of this is potassium, commonly found in Hogey's favorite snack, bananas.

131
00:06:31,360 --> 00:06:34,640
Speaker 5: They have half life of one point four billion years.

132
00:06:34,960 --> 00:06:40,919
Speaker 5: So it's definitely not just experimental and also not a guesswork.

133
00:06:41,120 --> 00:06:45,280
Speaker 5: So I am really curious about the actual answer.

134
00:06:45,800 --> 00:06:49,040
Speaker 2: All right, interesting question, I guess. Samya's question is how

135
00:06:49,080 --> 00:06:52,960
Speaker 2: do you know stuff? Daniel, like, have you actually measured

136
00:06:54,240 --> 00:06:56,560
Speaker 2: the half life of some things that maybe take billions

137
00:06:56,560 --> 00:06:57,520
Speaker 2: of years to decay?

138
00:06:57,720 --> 00:06:59,600
Speaker 1: Yeah, it's a good question. And I like that what

139
00:06:59,720 --> 00:07:03,440
Speaker 1: he did in something very practical. Bananas of course. And

140
00:07:03,640 --> 00:07:05,599
Speaker 1: it's a good question how we can measure these things

141
00:07:05,600 --> 00:07:07,599
Speaker 1: that take like a billion years to happen, because we

142
00:07:07,640 --> 00:07:10,560
Speaker 1: haven't been doing science for a billion years.

143
00:07:10,360 --> 00:07:14,320
Speaker 2: Right right, humans haven't been around for for a billion years, right.

144
00:07:14,240 --> 00:07:16,320
Speaker 1: Yeah, So if something takes a billion years to happen,

145
00:07:16,520 --> 00:07:19,120
Speaker 1: you can't possibly measure it, right. But the answer here

146
00:07:19,400 --> 00:07:22,480
Speaker 1: lies in understanding what people mean when they say half life.

147
00:07:22,520 --> 00:07:24,600
Speaker 1: If the half life of potassium is one point four

148
00:07:24,640 --> 00:07:27,120
Speaker 1: billion years, that doesn't mean you have to wait one

149
00:07:27,120 --> 00:07:31,119
Speaker 1: point four billion years for anything to happen. The half

150
00:07:31,200 --> 00:07:34,640
Speaker 1: life is the time it takes on average for half

151
00:07:34,760 --> 00:07:37,640
Speaker 1: of the atoms to decay. So if you wait one

152
00:07:37,680 --> 00:07:39,840
Speaker 1: point four billion years, that means half of them are

153
00:07:39,960 --> 00:07:41,880
Speaker 1: decayed and half of them have not. But some of

154
00:07:41,880 --> 00:07:44,200
Speaker 1: them may have decayed very early on, in the first

155
00:07:44,240 --> 00:07:46,720
Speaker 1: few seconds you were watching, or the first few minutes

156
00:07:47,160 --> 00:07:50,400
Speaker 1: you were watching, because half life is per atom, it's

157
00:07:50,440 --> 00:07:52,280
Speaker 1: really the time for an atom to have a fifty

158
00:07:52,320 --> 00:07:53,720
Speaker 1: percent chance of decaying.

159
00:07:53,880 --> 00:07:55,800
Speaker 2: Well, what's kind of interesting about the half life is

160
00:07:55,800 --> 00:07:58,920
Speaker 2: that it's almost always true, right, Like if you have

161
00:07:59,400 --> 00:08:02,040
Speaker 2: a ton of them material, it'll take a certain number

162
00:08:02,080 --> 00:08:04,760
Speaker 2: of years to decay down to half, But if you

163
00:08:04,760 --> 00:08:06,760
Speaker 2: have a little bit of that material, you'll still take

164
00:08:06,760 --> 00:08:08,880
Speaker 2: the same amount of time to decay down to half

165
00:08:08,880 --> 00:08:09,840
Speaker 2: of that much material.

166
00:08:09,960 --> 00:08:12,840
Speaker 1: Yeah, because it's relative and it's per atom, right. Every

167
00:08:12,920 --> 00:08:15,679
Speaker 1: atom is independent. They don't affect each other. It doesn't

168
00:08:15,720 --> 00:08:18,640
Speaker 1: matter how many atoms you have. You start from one hundred,

169
00:08:18,880 --> 00:08:20,800
Speaker 1: it takes the half life to get down to fifty.

170
00:08:20,840 --> 00:08:22,960
Speaker 1: You start from a billion, it takes that half life

171
00:08:22,960 --> 00:08:25,320
Speaker 1: to get down from a billion to half a billion,

172
00:08:25,560 --> 00:08:27,640
Speaker 1: because you could just break that billion into chunks of

173
00:08:27,640 --> 00:08:31,040
Speaker 1: one hundred, each of which then decay down into fifties.

174
00:08:31,120 --> 00:08:33,280
Speaker 2: Right, Right, like a banana would take a billion years

175
00:08:33,280 --> 00:08:36,440
Speaker 2: to decay, whether it's a tiny little banana or a humongous,

176
00:08:36,640 --> 00:08:37,760
Speaker 2: galaxy sized banana.

177
00:08:38,000 --> 00:08:41,559
Speaker 1: Yeah, exactly, because they don't interact, right, they're all independent,

178
00:08:41,600 --> 00:08:43,760
Speaker 1: and so it doesn't matter how many you have. And

179
00:08:43,800 --> 00:08:46,320
Speaker 1: the key to understanding how you could measure something that

180
00:08:46,400 --> 00:08:49,440
Speaker 1: takes a billion years is that stuff is happening even

181
00:08:49,480 --> 00:08:52,400
Speaker 1: in the first few moments potentially, and that's because every

182
00:08:52,480 --> 00:08:55,680
Speaker 1: atom has the same probability. They don't have like an age.

183
00:08:55,960 --> 00:08:58,320
Speaker 1: It's not like a clock inside of them. It says, oh,

184
00:08:58,320 --> 00:09:00,880
Speaker 1: somebody's been watching me for a billion years or for

185
00:09:00,920 --> 00:09:03,480
Speaker 1: a million years, it's time for me to decay. Every

186
00:09:03,600 --> 00:09:06,319
Speaker 1: moment the atom has like a fresh chance to decay,

187
00:09:06,640 --> 00:09:08,800
Speaker 1: and it rolls a die. It's like a die with

188
00:09:08,840 --> 00:09:11,480
Speaker 1: sixty million sides or something, and one side says decay

189
00:09:11,520 --> 00:09:13,360
Speaker 1: and the other side say don't. And every moment the

190
00:09:13,440 --> 00:09:16,959
Speaker 1: universe is rolling that die. So the probability for an

191
00:09:16,960 --> 00:09:21,120
Speaker 1: individual atom to decay is constant in time, right, which

192
00:09:21,160 --> 00:09:23,520
Speaker 1: means there's always a chance for any atom to decay.

193
00:09:23,559 --> 00:09:25,880
Speaker 1: It's just a question of like how long it takes

194
00:09:26,080 --> 00:09:28,280
Speaker 1: for half of them to eventually hit that.

195
00:09:28,280 --> 00:09:29,880
Speaker 2: Number, or, as you said, how long it takes for

196
00:09:29,920 --> 00:09:32,360
Speaker 2: it to have that particular atom to have a fifty

197
00:09:32,400 --> 00:09:34,960
Speaker 2: percent chance of decaying exactly, Like, if you just give

198
00:09:35,000 --> 00:09:38,280
Speaker 2: it a minute, probably that it's going to decay is

199
00:09:38,400 --> 00:09:41,000
Speaker 2: probably super duper small. If you give it ten years,

200
00:09:41,080 --> 00:09:42,840
Speaker 2: it's a little bit bigger. If you give it a

201
00:09:42,920 --> 00:09:45,319
Speaker 2: billion years, then there's a fifty percent chance that it's

202
00:09:45,360 --> 00:09:46,240
Speaker 2: going to decay by.

203
00:09:46,080 --> 00:09:49,920
Speaker 1: Then, exactly. And even after a minute or a moment,

204
00:09:50,000 --> 00:09:53,120
Speaker 1: there's still a non zero chance of it decaying, right,

205
00:09:53,360 --> 00:09:55,600
Speaker 1: You have a single potassium atom, say the half life

206
00:09:55,679 --> 00:09:57,440
Speaker 1: is a billion years, I haven't even looked it up.

207
00:09:57,520 --> 00:10:00,440
Speaker 1: It still has a chance of decaying after the first

208
00:10:00,440 --> 00:10:02,280
Speaker 1: moment it rolls that die and it might hit it

209
00:10:02,320 --> 00:10:04,960
Speaker 1: the very first time, right, and decay right there, even

210
00:10:05,000 --> 00:10:07,440
Speaker 1: if it's half life is a billion years. A long

211
00:10:07,480 --> 00:10:11,040
Speaker 1: half life comes from having a small probability of decaying

212
00:10:11,080 --> 00:10:13,840
Speaker 1: at any given moment. A short half life comes from

213
00:10:13,880 --> 00:10:16,599
Speaker 1: having a high probability decaying. If like ninety percent of

214
00:10:16,640 --> 00:10:19,600
Speaker 1: the sides of that die, say, decay, then the stuff's

215
00:10:19,600 --> 00:10:21,080
Speaker 1: going to decay away pretty quickly.

216
00:10:21,240 --> 00:10:21,360
Speaker 4: Right.

217
00:10:21,360 --> 00:10:23,240
Speaker 2: But I think Tim would maybe have the same question

218
00:10:23,720 --> 00:10:26,559
Speaker 2: about the single atom, like, how do you know a

219
00:10:26,600 --> 00:10:29,200
Speaker 2: single atom of potassium takes a billion year to have

220
00:10:29,200 --> 00:10:32,040
Speaker 2: a fifty percent chance of decaying if you've never measured

221
00:10:32,160 --> 00:10:33,400
Speaker 2: one for billion years?

222
00:10:33,520 --> 00:10:35,360
Speaker 1: Yeah, And the key is not to look at a

223
00:10:35,400 --> 00:10:38,280
Speaker 1: single atom. So if you're looking for something really rare

224
00:10:38,360 --> 00:10:40,800
Speaker 1: to happen, but it could happen at any moment, or

225
00:10:40,800 --> 00:10:42,200
Speaker 1: you don't have to wait a billion years, it could

226
00:10:42,200 --> 00:10:44,000
Speaker 1: happen at any moment, the key is to look at

227
00:10:44,040 --> 00:10:46,559
Speaker 1: a lot of atoms. Right, If you have like one

228
00:10:46,640 --> 00:10:49,560
Speaker 1: in a billion chance for a potassium atom to decay

229
00:10:49,559 --> 00:10:52,040
Speaker 1: at any moment. Then you just need a billion of them,

230
00:10:52,360 --> 00:10:54,600
Speaker 1: or ten billion of them, or fifty billion of them,

231
00:10:54,720 --> 00:10:57,400
Speaker 1: and then you'll see one of them decay. So if

232
00:10:57,440 --> 00:11:00,079
Speaker 1: you start with a big enough blob of potassium atom,

233
00:11:00,240 --> 00:11:03,400
Speaker 1: you'll start to see them decay almost instantly. It'll still

234
00:11:03,400 --> 00:11:05,440
Speaker 1: take a billion years for half of them to decay,

235
00:11:05,480 --> 00:11:08,560
Speaker 1: because it's very rare for any individual one to decay.

236
00:11:08,760 --> 00:11:11,080
Speaker 1: But if you got lots of them, just like lots

237
00:11:11,080 --> 00:11:13,760
Speaker 1: of monkeys in your room with typewriters, pretty quickly one

238
00:11:13,760 --> 00:11:15,840
Speaker 1: of them is going to type up Shakespeare.

239
00:11:15,400 --> 00:11:18,360
Speaker 2: Right, But you're not measuring individual atom. Even if you

240
00:11:18,400 --> 00:11:21,920
Speaker 2: have a billion atoms of potassium, your experiment is not

241
00:11:21,960 --> 00:11:24,840
Speaker 2: going to be looking at an individual atom the decay.

242
00:11:25,000 --> 00:11:27,240
Speaker 1: It depends on the decay. Sometimes you can see an

243
00:11:27,240 --> 00:11:31,040
Speaker 1: individual decay if it's, for example, generates radiation, then you

244
00:11:31,040 --> 00:11:33,240
Speaker 1: could pick up a single particle. You know, we have

245
00:11:33,360 --> 00:11:37,320
Speaker 1: these very sensitive detectors that can see individual particles, So

246
00:11:37,400 --> 00:11:40,640
Speaker 1: in principle, yeah, you could see an individual atom decay.

247
00:11:40,760 --> 00:11:42,800
Speaker 1: In practice, you don't even have to be that sensitive,

248
00:11:43,400 --> 00:11:46,240
Speaker 1: so mostly you can just look for the decay products

249
00:11:46,559 --> 00:11:48,599
Speaker 1: and you'll see plenty of them, because the tricky is

250
00:11:48,600 --> 00:11:51,160
Speaker 1: it's not hard to have ten to the thirty atoms. Right.

251
00:11:51,200 --> 00:11:53,200
Speaker 1: Atoms are so small that just like a handful of

252
00:11:53,240 --> 00:11:56,439
Speaker 1: any element, is a huge number of atoms. So it's

253
00:11:56,480 --> 00:11:58,800
Speaker 1: not hard to get a huge number of them, which

254
00:11:58,840 --> 00:12:01,800
Speaker 1: means you can see really things happening just because you've

255
00:12:01,800 --> 00:12:04,800
Speaker 1: got so many little monkeys in that room all typing away.

256
00:12:05,160 --> 00:12:07,760
Speaker 2: I wonder when maybe the real answer or maybe the

257
00:12:07,760 --> 00:12:10,840
Speaker 2: best way to explain this is to explain that the

258
00:12:10,960 --> 00:12:14,160
Speaker 2: half life of something is really just an arbitrary number, right,

259
00:12:14,240 --> 00:12:16,360
Speaker 2: Like we just call it a halflight because that's something

260
00:12:16,360 --> 00:12:18,480
Speaker 2: that's kind of easy for our minds to graps, like, oh,

261
00:12:18,480 --> 00:12:21,320
Speaker 2: it's when fifty percent of it the case, But really

262
00:12:21,440 --> 00:12:23,960
Speaker 2: that number of the half life is just the rate

263
00:12:24,000 --> 00:12:26,760
Speaker 2: of dec and you can measure that also in like

264
00:12:26,960 --> 00:12:29,040
Speaker 2: not the halflight, but like the quarter life of something,

265
00:12:29,480 --> 00:12:31,760
Speaker 2: or the one tenth of a life of something or

266
00:12:31,840 --> 00:12:34,240
Speaker 2: the one million time of something, and all of those

267
00:12:34,320 --> 00:12:37,400
Speaker 2: rates are basically the same. They're all related, like once

268
00:12:37,440 --> 00:12:39,080
Speaker 2: you know one, you know all the other ones.

269
00:12:39,320 --> 00:12:42,600
Speaker 1: Yeah, there's definitely an arbitrary element there, right, The fact

270
00:12:42,600 --> 00:12:45,559
Speaker 1: that we choose to define the half life at fifty percent.

271
00:12:45,600 --> 00:12:47,679
Speaker 1: You're right, you could choose to define the quarter life

272
00:12:47,840 --> 00:12:50,640
Speaker 1: or the tenth life, or the ninety percent life or whatever.

273
00:12:50,960 --> 00:12:53,959
Speaker 1: Half life is an arbitrary choice, but it also does

274
00:12:54,000 --> 00:12:57,440
Speaker 1: reflect something which is not arbitrary, which is the decay probability.

275
00:12:57,520 --> 00:13:00,000
Speaker 1: So it determined by that decay probability. But you're right,

276
00:13:00,080 --> 00:13:03,520
Speaker 1: that decay probability at any given moment also could determine

277
00:13:03,559 --> 00:13:05,640
Speaker 1: the quarter life or the tenth life. It's just a

278
00:13:05,679 --> 00:13:08,960
Speaker 1: standard we choose for comparing things. And we know that

279
00:13:09,000 --> 00:13:11,720
Speaker 1: a short half life means a high probability to decay

280
00:13:11,760 --> 00:13:14,400
Speaker 1: at any moment. A long half life means a small

281
00:13:14,520 --> 00:13:16,959
Speaker 1: probabilities to decay at any moment. That's why you get

282
00:13:17,000 --> 00:13:19,240
Speaker 1: more of them. But you can actually measure things that

283
00:13:19,280 --> 00:13:23,120
Speaker 1: happen very very rarely as long as you have enough examples.

284
00:13:23,400 --> 00:13:25,200
Speaker 2: Right, So then, like if you wanted to measure the

285
00:13:25,320 --> 00:13:28,000
Speaker 2: half life or the dek rate of potassium, you wouldn't

286
00:13:28,040 --> 00:13:30,200
Speaker 2: have to wait a billion years. You would maybe just

287
00:13:30,360 --> 00:13:32,839
Speaker 2: wait one year or ten years and see how much

288
00:13:32,880 --> 00:13:36,240
Speaker 2: of that blob of potassium you have decays, and maybe

289
00:13:36,360 --> 00:13:39,600
Speaker 2: it's you know, one millionth or one billionth of the

290
00:13:39,640 --> 00:13:43,080
Speaker 2: material has decayed. But even that one billionth tells you

291
00:13:43,160 --> 00:13:45,760
Speaker 2: basically the rate of decay, which then lets you extrapolate

292
00:13:46,120 --> 00:13:47,400
Speaker 2: to what the half life would be.

293
00:13:47,559 --> 00:13:50,360
Speaker 1: Yeah, exactly. You don't have to observe half of the

294
00:13:50,440 --> 00:13:52,440
Speaker 1: decaying to measure the half life. You just have to

295
00:13:52,480 --> 00:13:54,280
Speaker 1: measure the decay rate. And as long as you have

296
00:13:54,440 --> 00:13:57,160
Speaker 1: enough examples, you'll see some decay and you can measure

297
00:13:57,200 --> 00:13:59,400
Speaker 1: that decay rate. You can even do crazy things like

298
00:13:59,679 --> 00:14:02,880
Speaker 1: measure sure the lifetime of a proton to be longer

299
00:14:02,880 --> 00:14:04,840
Speaker 1: than the age of a universe.

300
00:14:04,559 --> 00:14:06,280
Speaker 2: Which is true, right, that's what you've measured.

301
00:14:06,360 --> 00:14:09,200
Speaker 1: Yeah, because we've never seen a proton decay, so we

302
00:14:09,280 --> 00:14:12,760
Speaker 1: don't know do protons live forever or do they just

303
00:14:12,840 --> 00:14:15,840
Speaker 1: live a very very long time. And we've watched a

304
00:14:15,840 --> 00:14:17,960
Speaker 1: bunch of protons waiting to see if one of them

305
00:14:18,040 --> 00:14:21,080
Speaker 1: decays and never seen one, And so we can say, well,

306
00:14:21,120 --> 00:14:23,880
Speaker 1: the lifetime of a proton is at least ten to

307
00:14:23,920 --> 00:14:27,120
Speaker 1: the thirty one years, which is a huge number. Right.

308
00:14:27,200 --> 00:14:29,200
Speaker 1: The age of the universe is like ten to the

309
00:14:29,280 --> 00:14:30,360
Speaker 1: thirteen years.

310
00:14:30,440 --> 00:14:32,600
Speaker 2: But have you ever seen a proton decay?

311
00:14:32,800 --> 00:14:34,280
Speaker 1: Never seen a single one, never.

312
00:14:34,200 --> 00:14:36,920
Speaker 2: Seen never seen one. But you've also never seen an

313
00:14:36,960 --> 00:14:40,520
Speaker 2: electron decay. That's for electrons. You say that it never decays.

314
00:14:40,600 --> 00:14:42,840
Speaker 1: We say it never decays. We don't actually know that.

315
00:14:42,880 --> 00:14:45,560
Speaker 1: We just know that they're stable on time scales that

316
00:14:45,560 --> 00:14:47,760
Speaker 1: are much longer than the life of the universe. But yeah,

317
00:14:47,800 --> 00:14:48,560
Speaker 1: they could decay.

318
00:14:48,720 --> 00:14:50,560
Speaker 2: Did you just say that You say things without really

319
00:14:50,560 --> 00:14:51,160
Speaker 2: knowing them.

320
00:14:51,240 --> 00:14:53,320
Speaker 1: I mean, there's always a qualification when we say we

321
00:14:53,360 --> 00:14:56,560
Speaker 1: know something right. Nothing we know about physics could be true.

322
00:14:56,560 --> 00:14:59,040
Speaker 1: It could be that everything is upturned later or shown

323
00:14:59,080 --> 00:15:02,040
Speaker 1: to just be an approximate. In the case of an electron,

324
00:15:02,360 --> 00:15:05,080
Speaker 1: we call it stable because that's what stable means for us, Like,

325
00:15:05,160 --> 00:15:07,200
Speaker 1: it doesn't decay over billions and billions of years. It

326
00:15:07,280 --> 00:15:10,160
Speaker 1: might live forever, or it might decay after ten to

327
00:15:10,160 --> 00:15:12,600
Speaker 1: the fifty years. We definitely know a lot about the

328
00:15:12,640 --> 00:15:15,280
Speaker 1: lifetime of the electron, but we don't know everything about it.

329
00:15:15,320 --> 00:15:17,320
Speaker 2: But then, what's the difference between an electron and proton?

330
00:15:17,360 --> 00:15:19,080
Speaker 2: That makes you think that a proton has a lot

331
00:15:19,080 --> 00:15:20,880
Speaker 2: of half life but an electron does not.

332
00:15:21,000 --> 00:15:24,880
Speaker 1: Yeah, that's a good question, because the proton is not fundamental, right,

333
00:15:24,920 --> 00:15:27,880
Speaker 1: it's an assembly of smaller bits. We already know that

334
00:15:28,040 --> 00:15:30,840
Speaker 1: the electron might be fundamental might just be the electron

335
00:15:30,960 --> 00:15:32,840
Speaker 1: is made of the electron, in which case it's stable.

336
00:15:33,320 --> 00:15:36,000
Speaker 1: But if it's made of smaller things that could change

337
00:15:36,040 --> 00:15:38,640
Speaker 1: their configuration and turn into something else, it'd be more

338
00:15:38,760 --> 00:15:41,240
Speaker 1: likely to be unstable. And we know the proton is

339
00:15:41,240 --> 00:15:43,360
Speaker 1: made of smaller bits, right, there's just an arrangement of

340
00:15:43,440 --> 00:15:46,840
Speaker 1: quarks and the slightly different arrangements of those same quarks.

341
00:15:46,920 --> 00:15:49,320
Speaker 1: The neutron is not stable. The neutron only lasts for

342
00:15:49,360 --> 00:15:52,000
Speaker 1: like eleven minutes. You got a bunch of neutrons in space,

343
00:15:52,040 --> 00:15:54,840
Speaker 1: they'll decay really quickly. So it's sort of a mystery

344
00:15:54,920 --> 00:15:57,960
Speaker 1: why the proton is stable. And there's lots of juicy

345
00:15:58,000 --> 00:16:00,680
Speaker 1: theories out there that particle theorists life because they solve

346
00:16:00,720 --> 00:16:04,440
Speaker 1: other problems that predict the proton should decay, And all

347
00:16:04,480 --> 00:16:06,520
Speaker 1: those theories are ruined by the fact that the proton

348
00:16:06,560 --> 00:16:08,960
Speaker 1: doesn't decay. So there's a bunch of experiments out there

349
00:16:08,960 --> 00:16:10,520
Speaker 1: hoping to see a proton decay.

350
00:16:10,720 --> 00:16:13,080
Speaker 2: Interesting, Now, do you have a juicy theory about the

351
00:16:13,200 --> 00:16:14,480
Speaker 2: decay of bananas?

352
00:16:15,840 --> 00:16:16,040
Speaker 1: Yes?

353
00:16:16,160 --> 00:16:18,280
Speaker 2: Like, can you make banana juice? Is that such a thing?

354
00:16:18,400 --> 00:16:20,920
Speaker 1: It's called the smoothie. My theory is that when bananas decay,

355
00:16:20,920 --> 00:16:22,280
Speaker 1: they get way too juicy.

356
00:16:22,000 --> 00:16:24,720
Speaker 2: And griss mmm, too soft, too softly.

357
00:16:26,240 --> 00:16:28,200
Speaker 1: But it's really cool to think that you can say

358
00:16:28,240 --> 00:16:31,680
Speaker 1: something about protons over like ten to the thirty years,

359
00:16:32,000 --> 00:16:35,640
Speaker 1: even though no proton has existed that long, not even

360
00:16:35,680 --> 00:16:37,640
Speaker 1: a tiny fraction of that length.

361
00:16:37,800 --> 00:16:40,120
Speaker 2: Yeah, or even about potassium, right, it's amazing. We can

362
00:16:40,160 --> 00:16:41,880
Speaker 2: say that the potasium in a banana is not going

363
00:16:41,920 --> 00:16:45,080
Speaker 2: to decay for one point four billion years because we

364
00:16:45,160 --> 00:16:47,800
Speaker 2: know we've seen it decay, and it decays super duper slowly.

365
00:16:48,360 --> 00:16:50,360
Speaker 2: So from that you can extrapolate that it's going to

366
00:16:50,400 --> 00:16:52,680
Speaker 2: take I want and have billion years to decay to

367
00:16:53,200 --> 00:16:55,120
Speaker 2: half of its initial quantity.

368
00:16:55,280 --> 00:16:57,840
Speaker 1: Yeah, exactly. So if you want to see something do

369
00:16:57,960 --> 00:17:00,640
Speaker 1: something rare, just get a whole lot of them, that's

370
00:17:00,680 --> 00:17:01,160
Speaker 1: the answer.

371
00:17:01,280 --> 00:17:02,840
Speaker 2: Are you saying people should go out there and get

372
00:17:02,840 --> 00:17:04,160
Speaker 2: a lot of bananas.

373
00:17:06,080 --> 00:17:07,720
Speaker 1: If you want to see bananas do something right, If

374
00:17:07,760 --> 00:17:09,480
Speaker 1: you think bananas get up and dance in the middle

375
00:17:09,480 --> 00:17:11,400
Speaker 1: of the night and you think that's pretty rare, then yeah,

376
00:17:11,480 --> 00:17:13,680
Speaker 1: get a lot of bananas, watch them all at night

377
00:17:13,720 --> 00:17:14,439
Speaker 1: and see what they do.

378
00:17:15,520 --> 00:17:15,680
Speaker 4: Well.

379
00:17:15,680 --> 00:17:18,159
Speaker 2: The half life of bananas in my house is pretty short.

380
00:17:18,480 --> 00:17:20,840
Speaker 2: Now that my son is growing up and he's doing

381
00:17:20,880 --> 00:17:24,879
Speaker 2: all kinds of exercise, and he's downing those bananas pretty

382
00:17:24,960 --> 00:17:25,520
Speaker 2: pretty fast.

383
00:17:25,640 --> 00:17:27,159
Speaker 1: Does he do that thing kids do, which is like

384
00:17:27,240 --> 00:17:29,040
Speaker 1: just eat half a banana and then leave it around?

385
00:17:29,119 --> 00:17:31,080
Speaker 1: Is that what half life of banana means in your house?

386
00:17:32,359 --> 00:17:32,520
Speaker 4: Well?

387
00:17:32,520 --> 00:17:34,359
Speaker 2: I think he learned that for me. But yeah, he

388
00:17:34,440 --> 00:17:36,360
Speaker 2: takes a knife and he cuts a banana and then

389
00:17:36,720 --> 00:17:39,160
Speaker 2: he'll eat the other half the next day. All right, well,

390
00:17:39,280 --> 00:17:42,080
Speaker 2: great question, thank you, Samia, And let's get to our

391
00:17:42,160 --> 00:17:45,840
Speaker 2: other questions here today. We have questions about more bananas,

392
00:17:45,840 --> 00:17:49,439
Speaker 2: it seems, and black holes and or maybe both, So

393
00:17:49,600 --> 00:17:52,639
Speaker 2: let's dig into that. But first let's take a quick break.

394
00:18:05,200 --> 00:18:07,800
Speaker 2: All right, we're taking listener questions here today, and our

395
00:18:07,880 --> 00:18:10,040
Speaker 2: next question comes from Bill.

396
00:18:10,000 --> 00:18:12,440
Speaker 4: Hi, Daniel, and Jorre. This is Bill. I was thinking

397
00:18:12,480 --> 00:18:15,520
Speaker 4: about banana radiation and realized that while half lives of

398
00:18:15,600 --> 00:18:18,720
Speaker 4: various decays are well characterized, I can't find anything about

399
00:18:18,720 --> 00:18:21,760
Speaker 4: how long a decay actually takes. It must take some

400
00:18:21,800 --> 00:18:23,920
Speaker 4: time for an atom of one element to turn into

401
00:18:23,960 --> 00:18:27,840
Speaker 4: another element and various particles. Is this time unmeasurably short?

402
00:18:27,960 --> 00:18:30,560
Speaker 4: Does it vary for different types of decay? Thanks?

403
00:18:30,760 --> 00:18:30,879
Speaker 1: All?

404
00:18:30,960 --> 00:18:35,199
Speaker 2: Right, another banana radiation half Live question? Is that a

405
00:18:35,200 --> 00:18:38,399
Speaker 2: theme today? Were you feeling really bananas today?

406
00:18:38,600 --> 00:18:40,760
Speaker 1: It wasn't me. I think Bill and Sammy I just

407
00:18:40,800 --> 00:18:43,280
Speaker 1: wrote in about bananas decaying at the same moment.

408
00:18:43,320 --> 00:18:46,119
Speaker 2: It's sort of amazing at the same time, like the

409
00:18:46,160 --> 00:18:46,960
Speaker 2: same timestamp.

410
00:18:47,080 --> 00:18:49,639
Speaker 1: Yeah, I think some potassium particle must have triggered inside

411
00:18:49,680 --> 00:18:50,240
Speaker 1: their brains.

412
00:18:50,760 --> 00:18:54,240
Speaker 2: Yeah, exactly, what's the probability of that happening. It's bananas.

413
00:18:54,359 --> 00:18:57,879
Speaker 1: Their brains are banana tabled quantum bananament.

414
00:18:58,040 --> 00:19:00,480
Speaker 2: Well, you know you don't have to answer these in order, Daniel,

415
00:19:01,160 --> 00:19:03,080
Speaker 2: we could have saved spread out some of the banana

416
00:19:03,240 --> 00:19:06,960
Speaker 2: conversations across several listener question episodes.

417
00:19:07,119 --> 00:19:09,600
Speaker 1: I'm too busy answering listener emails to organize these.

418
00:19:09,720 --> 00:19:11,800
Speaker 2: I see, you're too busy directing your grad students to

419
00:19:11,840 --> 00:19:14,200
Speaker 2: answer the emails.

420
00:19:14,960 --> 00:19:16,840
Speaker 1: I am not allowed to get my grad students to

421
00:19:16,880 --> 00:19:18,040
Speaker 1: work on this project for free.

422
00:19:18,119 --> 00:19:22,399
Speaker 2: Absolutely no, oh for free? I see. But if you

423
00:19:22,400 --> 00:19:24,560
Speaker 2: pay them bananas, then it's totally kosher.

424
00:19:25,520 --> 00:19:27,159
Speaker 1: Do you want to pay my grad students out of

425
00:19:27,200 --> 00:19:28,239
Speaker 1: the podcast? Let's do it.

426
00:19:30,600 --> 00:19:32,760
Speaker 2: If we can pay them in bananas, Sure, that sounds

427
00:19:32,800 --> 00:19:35,080
Speaker 2: like a great deal. And it'll be good for them.

428
00:19:35,280 --> 00:19:37,880
Speaker 1: You know, the grad students here unionized recently, so bananas

429
00:19:37,880 --> 00:19:39,480
Speaker 1: are definitely off the table for payment.

430
00:19:39,720 --> 00:19:42,600
Speaker 2: Oh, I don't know, are they Have you read the

431
00:19:42,880 --> 00:19:46,960
Speaker 2: union rules? Maybe they make exceptions for bananas, don't they do?

432
00:19:48,480 --> 00:19:50,480
Speaker 1: That was not a clause on the bargaining table.

433
00:19:50,760 --> 00:19:53,480
Speaker 2: I see, I see to slippery a point of contention.

434
00:19:54,119 --> 00:19:56,920
Speaker 2: All right, Well back to the question. Bill has a question,

435
00:19:56,960 --> 00:19:58,880
Speaker 2: but it's a kind of a different question about banana

436
00:19:59,040 --> 00:20:01,760
Speaker 2: radiation and the case. He's not asking like how long

437
00:20:01,800 --> 00:20:03,879
Speaker 2: it takes a bit the potassium in a banana de decay,

438
00:20:03,880 --> 00:20:06,800
Speaker 2: but basically how long it takes for something to decay, Like,

439
00:20:06,800 --> 00:20:09,840
Speaker 2: if something decays, does it happen instantly or does it

440
00:20:09,880 --> 00:20:11,359
Speaker 2: take a certain amount of time.

441
00:20:11,720 --> 00:20:14,720
Speaker 1: Yeah, this is a super awesome question because it really

442
00:20:14,760 --> 00:20:18,240
Speaker 1: reveals the limits of our knowledge and also how those

443
00:20:18,280 --> 00:20:20,840
Speaker 1: limits have changed. I mean, the short answer is for

444
00:20:20,960 --> 00:20:24,800
Speaker 1: some things it's effectively instantaneous, because we can't measure how

445
00:20:24,840 --> 00:20:27,639
Speaker 1: fast it is, like an individual decay, how long does

446
00:20:27,680 --> 00:20:30,280
Speaker 1: it take one atom to turn into another kind, or

447
00:20:30,440 --> 00:20:32,480
Speaker 1: for a neutron to turn into a proton, or for

448
00:20:32,560 --> 00:20:35,200
Speaker 1: inverse beta decay to happen? For some processes, we can't

449
00:20:35,200 --> 00:20:37,840
Speaker 1: measure it, so we treat it as instantaneous though we

450
00:20:37,880 --> 00:20:39,359
Speaker 1: don't actually know what.

451
00:20:39,240 --> 00:20:41,360
Speaker 2: Do you mean we can measure like it happens too

452
00:20:41,400 --> 00:20:43,919
Speaker 2: fast or is just impossible to measure.

453
00:20:44,119 --> 00:20:46,800
Speaker 1: I don't think it's impossible to measure in principle, Like

454
00:20:46,920 --> 00:20:49,840
Speaker 1: if we had higher energy probes and we could look

455
00:20:49,880 --> 00:20:53,040
Speaker 1: inside and see the mechanics of what was happening, then

456
00:20:53,080 --> 00:20:55,879
Speaker 1: we would see that something is happening, and that takes time.

457
00:20:56,080 --> 00:20:57,760
Speaker 1: And because we can't see inside and we don't have

458
00:20:57,840 --> 00:21:01,639
Speaker 1: like fast enough measuring devices, it's as if it's instantaneous

459
00:21:01,720 --> 00:21:04,040
Speaker 1: in some cases but not in others. And we've made

460
00:21:04,040 --> 00:21:07,800
Speaker 1: some progress. So, for example, we used to treat beta

461
00:21:07,840 --> 00:21:11,320
Speaker 1: decay when a neutron turns into a proton and emits

462
00:21:11,320 --> 00:21:14,439
Speaker 1: an electron, as an instantaneous thing. We're like, well, this

463
00:21:14,600 --> 00:21:16,760
Speaker 1: is just one thing that happens. A neutron turns into

464
00:21:16,800 --> 00:21:20,320
Speaker 1: a proton and an electron boom, And like fifty years ago,

465
00:21:20,400 --> 00:21:22,840
Speaker 1: we couldn't see inside the neutron or the proton to

466
00:21:22,880 --> 00:21:25,919
Speaker 1: understand like what was actually happening there. We just treated

467
00:21:25,920 --> 00:21:28,200
Speaker 1: them all as point particles and we said there was

468
00:21:28,240 --> 00:21:30,399
Speaker 1: a before and there's an after and in the middle,

469
00:21:30,440 --> 00:21:32,280
Speaker 1: we don't know what happens. We just treat it as

470
00:21:32,320 --> 00:21:33,560
Speaker 1: an instantaneous step.

471
00:21:34,240 --> 00:21:37,360
Speaker 2: But I guess maybe more fundamentally, do you think these

472
00:21:37,400 --> 00:21:40,520
Speaker 2: things are happening instantaneously or do you think all of

473
00:21:40,560 --> 00:21:44,840
Speaker 2: these things decays particle interactions? Do they all take some time?

474
00:21:45,040 --> 00:21:47,800
Speaker 1: Everything in the universe definitely takes some time, even if

475
00:21:47,800 --> 00:21:52,040
Speaker 1: you're transitioning between fundamental states like say, for example, you

476
00:21:52,119 --> 00:21:54,800
Speaker 1: have a photon and it's turning into an electron and

477
00:21:54,800 --> 00:21:57,360
Speaker 1: a positron. Right, we don't know what's inside the photon.

478
00:21:57,400 --> 00:21:59,800
Speaker 1: We don't know what's inside the electron depositron, We don't

479
00:21:59,840 --> 00:22:02,800
Speaker 1: know what's happening there. So assume that those are fundamental

480
00:22:03,080 --> 00:22:05,560
Speaker 1: things in the universe. When a photon turns into an

481
00:22:05,560 --> 00:22:08,800
Speaker 1: electron apostoitron, you can ask like, is that instantaneous? Is

482
00:22:08,840 --> 00:22:11,119
Speaker 1: there a moment when it's a photon and then a

483
00:22:11,160 --> 00:22:13,880
Speaker 1: moment when it's an electron apositron and nothing in between.

484
00:22:14,040 --> 00:22:16,200
Speaker 1: The way to think about a quantum mechanically, which is

485
00:22:16,240 --> 00:22:18,679
Speaker 1: the right way to think about everything microscopically, is to

486
00:22:18,720 --> 00:22:21,320
Speaker 1: think about the probabilities changing. It's like one hundred percent

487
00:22:21,440 --> 00:22:23,440
Speaker 1: chance of being a photon, and then that probably starts

488
00:22:23,480 --> 00:22:25,280
Speaker 1: to drop, and now it's like fifty percent chance of

489
00:22:25,320 --> 00:22:27,760
Speaker 1: being a photon and fifty percent chance of being an electron,

490
00:22:27,840 --> 00:22:31,000
Speaker 1: an a positron, or two other particles. And then that

491
00:22:31,080 --> 00:22:33,560
Speaker 1: probability changes and now it's like one percent chance of

492
00:22:33,640 --> 00:22:36,560
Speaker 1: still being a photon. So the probability changes smoothly.

493
00:22:36,920 --> 00:22:39,639
Speaker 2: So you're saying, so there's two things that can happen

494
00:22:40,320 --> 00:22:43,639
Speaker 2: that can change, Like the actual electron can change, and

495
00:22:43,680 --> 00:22:47,320
Speaker 2: then the probability of it what it is can also change.

496
00:22:47,800 --> 00:22:51,360
Speaker 2: Are you saying like in quantum mechanics, nothing is ever

497
00:22:51,440 --> 00:22:54,560
Speaker 2: something like nothing is there an electron or nothing's ever

498
00:22:54,600 --> 00:22:57,640
Speaker 2: a proton or a photon. Things just have the probability

499
00:22:57,640 --> 00:22:59,720
Speaker 2: of being an electron or the probability of being a

500
00:22:59,760 --> 00:23:01,480
Speaker 2: photo if you probe them.

501
00:23:01,600 --> 00:23:03,480
Speaker 1: Yeah, exactly, And we can try to make it simpler

502
00:23:03,560 --> 00:23:06,160
Speaker 1: even just think about like what a single electron does.

503
00:23:06,760 --> 00:23:08,560
Speaker 1: We talked once in the podcast about like how an

504
00:23:08,600 --> 00:23:12,119
Speaker 1: electron changes from energy levels? Is that instantaneous when it

505
00:23:12,160 --> 00:23:14,760
Speaker 1: absorbs a photon, Does it like jump from one an

506
00:23:14,880 --> 00:23:17,520
Speaker 1: energy level to another, or does it move from that

507
00:23:17,640 --> 00:23:20,119
Speaker 1: energy level to the other. Well, the electron can't be

508
00:23:20,320 --> 00:23:22,840
Speaker 1: in between energy levels, so how does it like get

509
00:23:22,920 --> 00:23:26,000
Speaker 1: from here to there? What happens is that the probability

510
00:23:26,000 --> 00:23:28,199
Speaker 1: for it to be in the lower energy level starts

511
00:23:28,200 --> 00:23:29,639
Speaker 1: to drop, and the probability for it to be in

512
00:23:29,680 --> 00:23:32,560
Speaker 1: the higher energy level starts to raise, until it's effectively

513
00:23:32,560 --> 00:23:33,359
Speaker 1: one hundred percent.

514
00:23:33,560 --> 00:23:35,880
Speaker 2: Now do you know that for sure though? Or I mean,

515
00:23:35,960 --> 00:23:39,919
Speaker 2: isn't it technically possible for these probabilities to change instantaneously?

516
00:23:40,320 --> 00:23:41,520
Speaker 2: Because they're just math.

517
00:23:41,359 --> 00:23:45,479
Speaker 1: Right, they're just math. I love that we know this

518
00:23:45,720 --> 00:23:48,080
Speaker 1: for sure, only in the sense that this is how

519
00:23:48,119 --> 00:23:51,800
Speaker 1: the theory works, and the theory so far describes everything

520
00:23:51,840 --> 00:23:54,439
Speaker 1: we've seen, so it accurately predicts it. But there's always

521
00:23:54,440 --> 00:23:56,200
Speaker 1: bits of the theory that are like behind the curtain

522
00:23:56,200 --> 00:23:58,560
Speaker 1: that we can't see directly, and right now we're talking

523
00:23:58,600 --> 00:24:01,639
Speaker 1: about stuff we can't see, argument things that are not observed.

524
00:24:01,800 --> 00:24:04,680
Speaker 1: This is the calculation of what's happening really behind the scenes.

525
00:24:04,840 --> 00:24:06,240
Speaker 1: All you can do is shoot a photon at the

526
00:24:06,280 --> 00:24:08,639
Speaker 1: electron and measure its old energy level and it's new

527
00:24:08,720 --> 00:24:11,520
Speaker 1: energy level and make predictions for that. You can't see

528
00:24:11,560 --> 00:24:15,440
Speaker 1: these probabilities themselves transitioning. That's probably what you mean.

529
00:24:15,400 --> 00:24:18,639
Speaker 2: But you could potentially, right, I guess maybe that's what

530
00:24:18,680 --> 00:24:21,520
Speaker 2: I'm asking is that you can't see them change, or

531
00:24:22,000 --> 00:24:24,080
Speaker 2: that we don't have the technology to see them change. Like,

532
00:24:24,119 --> 00:24:26,400
Speaker 2: let's say I gave you magical powers, and I gave

533
00:24:26,400 --> 00:24:28,880
Speaker 2: you the ability to create this measuring device that has

534
00:24:28,960 --> 00:24:32,800
Speaker 2: infinite time resolution and infinite size resolution. Would you be

535
00:24:32,840 --> 00:24:36,359
Speaker 2: able to see these probability these change or would you

536
00:24:36,800 --> 00:24:38,520
Speaker 2: maybe see them change suddenly?

537
00:24:38,720 --> 00:24:41,399
Speaker 1: You can't see the probabilities directly, right, The probabilities or

538
00:24:41,440 --> 00:24:43,840
Speaker 1: consequences of the wave function, which is not something physical

539
00:24:43,880 --> 00:24:45,800
Speaker 1: we can measure. All we can do is measure the

540
00:24:45,800 --> 00:24:48,119
Speaker 1: electron and measure the photon. So if you gave me

541
00:24:48,240 --> 00:24:51,359
Speaker 1: infinite experimental powers, I could look set up a huge

542
00:24:51,440 --> 00:24:54,879
Speaker 1: number of these devices and shoot photons at them simultaneously,

543
00:24:55,119 --> 00:24:57,800
Speaker 1: and just like in the previous question, I could say, like, oh, look,

544
00:24:57,840 --> 00:25:00,160
Speaker 1: forty percent of the photons were absorbed or n twy

545
00:25:00,160 --> 00:25:02,400
Speaker 1: percent of them were absorbed. So that way I could

546
00:25:02,440 --> 00:25:05,600
Speaker 1: sort of measure the probabilities. But for an individual photon

547
00:25:05,640 --> 00:25:08,600
Speaker 1: an electron, I can't say, oh, here, this one has

548
00:25:08,600 --> 00:25:10,840
Speaker 1: a forty percent chance there, and that one has forty

549
00:25:10,880 --> 00:25:14,159
Speaker 1: percent chance here. I can calculate those things using the theory,

550
00:25:14,359 --> 00:25:17,720
Speaker 1: but I can't actually observe those things directly. And also crucially,

551
00:25:17,760 --> 00:25:21,320
Speaker 1: in the theory, probabilities never change suddenly. They always evolve

552
00:25:21,480 --> 00:25:24,879
Speaker 1: smoothly with time. That's again just part of the theory.

553
00:25:24,920 --> 00:25:27,639
Speaker 1: And you know, the theory could be totally wrong. We

554
00:25:27,680 --> 00:25:29,840
Speaker 1: have lots of questions about quantum mechanics and what's going

555
00:25:29,840 --> 00:25:32,159
Speaker 1: on inside this stuff that could be totally wrong. But

556
00:25:32,240 --> 00:25:35,520
Speaker 1: in our current picture, none of this stuff happens instantaneously.

557
00:25:35,560 --> 00:25:37,600
Speaker 1: But the way to think about it is the probabilities

558
00:25:37,800 --> 00:25:40,520
Speaker 1: changing smoothly, not the particles changing.

559
00:25:40,240 --> 00:25:43,000
Speaker 2: Instantly according to the theory, though.

560
00:25:42,920 --> 00:25:45,440
Speaker 1: Right according to the theory, and sometimes you can zoom

561
00:25:45,480 --> 00:25:48,399
Speaker 1: out and understand like the internal mechanisms of these particles,

562
00:25:48,720 --> 00:25:51,040
Speaker 1: like we were talking about earlier. We used to understand

563
00:25:51,040 --> 00:25:53,679
Speaker 1: a neutron just like changing into a proton and an

564
00:25:53,720 --> 00:25:56,240
Speaker 1: electron the way we just described, like, hey, there's a

565
00:25:56,240 --> 00:25:58,960
Speaker 1: probability for it to happen. Now we know though, about

566
00:25:59,000 --> 00:26:01,600
Speaker 1: what's going on inside the neutron, so we can talk

567
00:26:01,600 --> 00:26:04,560
Speaker 1: about what's actually happening and how long that takes. We've

568
00:26:04,560 --> 00:26:06,879
Speaker 1: like zoomed in and we can see, oh, when that

569
00:26:07,040 --> 00:26:10,600
Speaker 1: happens that's a down cork turning into an upcork and

570
00:26:10,640 --> 00:26:13,400
Speaker 1: emitting a w boson. We've like resolved this thing, which

571
00:26:13,560 --> 00:26:15,600
Speaker 1: you should just be a point in our theories. Now

572
00:26:15,600 --> 00:26:17,440
Speaker 1: we've like zoomed in and we've seen, oh no, it's

573
00:26:17,480 --> 00:26:21,120
Speaker 1: actually these little pieces interglocking and changing and doing their thing,

574
00:26:21,200 --> 00:26:22,760
Speaker 1: and that does take some time.

575
00:26:23,720 --> 00:26:25,120
Speaker 2: And how do you measure that time?

576
00:26:25,160 --> 00:26:25,320
Speaker 1: Then?

577
00:26:25,520 --> 00:26:27,399
Speaker 2: I know, in the large Hadron collider you have like

578
00:26:27,440 --> 00:26:30,520
Speaker 2: a series of detectors or their sensors, and you can

579
00:26:30,600 --> 00:26:33,159
Speaker 2: sort of trace the path and the track and the

580
00:26:33,280 --> 00:26:35,800
Speaker 2: what happens to these things after they smash up? Is

581
00:26:35,800 --> 00:26:37,679
Speaker 2: that how you tell how long something takes? Or are

582
00:26:37,720 --> 00:26:38,960
Speaker 2: you just guessing from the theory?

583
00:26:40,240 --> 00:26:44,520
Speaker 1: Just guessing from the theory the highest level of understanding

584
00:26:44,640 --> 00:26:48,520
Speaker 1: of the universe ever achieved by humans, Jorge calls guessing

585
00:26:48,560 --> 00:26:53,520
Speaker 1: from the theory. I love it. No, in some cases

586
00:26:53,600 --> 00:26:56,240
Speaker 1: this is just guessing from the theory. Like for example,

587
00:26:56,359 --> 00:26:58,920
Speaker 1: the dcay we just described talks about a w boson

588
00:26:58,960 --> 00:27:01,520
Speaker 1: a w boson for a very very short amount of

589
00:27:01,520 --> 00:27:04,160
Speaker 1: time ten to them, man is twenty four seconds, which

590
00:27:04,200 --> 00:27:06,960
Speaker 1: is much faster than anything we could actually measure. So

591
00:27:07,119 --> 00:27:09,359
Speaker 1: again we have a theoretical description of this, and we

592
00:27:09,400 --> 00:27:12,119
Speaker 1: think it takes that much time for this decay to

593
00:27:12,200 --> 00:27:14,400
Speaker 1: happen ten to minus twenty four seconds. But we could

594
00:27:14,480 --> 00:27:15,280
Speaker 1: never measure that.

595
00:27:15,280 --> 00:27:18,119
Speaker 2: For the probability to shift from being one thing to

596
00:27:18,200 --> 00:27:18,480
Speaker 2: the other.

597
00:27:18,960 --> 00:27:19,760
Speaker 1: Yes, exactly.

598
00:27:19,880 --> 00:27:21,880
Speaker 2: But I wonder if maybe Bill's question is like, when

599
00:27:21,920 --> 00:27:25,520
Speaker 2: it actually happens, does it take time or is it instantaneous?

600
00:27:25,800 --> 00:27:29,080
Speaker 2: Because you know, like these things are wiggles in some

601
00:27:29,200 --> 00:27:31,760
Speaker 2: quantum field out there in the universe. Do those wiggles

602
00:27:31,800 --> 00:27:35,400
Speaker 2: suddenly like pop into a different configuration or do they

603
00:27:36,280 --> 00:27:38,040
Speaker 2: you know, morph from one to the other.

604
00:27:38,160 --> 00:27:39,439
Speaker 1: The right way to think about it is that it

605
00:27:39,480 --> 00:27:42,280
Speaker 1: always takes time. Everything takes time. Nothing in the universe

606
00:27:42,400 --> 00:27:45,280
Speaker 1: is discontinuous. It's not like a slice where it's this

607
00:27:45,440 --> 00:27:47,840
Speaker 1: and then all of a sudden, it's that. Right. Everything

608
00:27:47,880 --> 00:27:50,440
Speaker 1: is smooth in the universe as far as we've discovered,

609
00:27:50,880 --> 00:27:53,360
Speaker 1: you know, and so even quantum mechanics, right, which likes

610
00:27:53,400 --> 00:27:56,920
Speaker 1: to have things be discrete and in chunks. It transforms

611
00:27:56,960 --> 00:27:59,879
Speaker 1: things smoothly through times. You look at the Shortener equation

612
00:28:00,000 --> 00:28:03,440
Speaker 1: for example, that's an equation for how wave functions change

613
00:28:03,600 --> 00:28:06,520
Speaker 1: through time as they interact with stuff and that's always smooth.

614
00:28:07,200 --> 00:28:10,200
Speaker 1: And so instead of thinking about like things popping from

615
00:28:10,200 --> 00:28:12,640
Speaker 1: one spot to another, you should think about their probabilities

616
00:28:12,680 --> 00:28:15,720
Speaker 1: as like sloshing around and so that always takes time.

617
00:28:15,960 --> 00:28:18,080
Speaker 2: That always takes time. And I guess part of Bill's

618
00:28:18,160 --> 00:28:21,480
Speaker 2: question was do different things take different amounts of time?

619
00:28:21,520 --> 00:28:25,639
Speaker 2: And that's the answer is yes, right, some things maybe

620
00:28:25,760 --> 00:28:26,240
Speaker 2: or maybe not.

621
00:28:26,560 --> 00:28:30,120
Speaker 1: Yes, absolutely different things take different amounts of time. For example,

622
00:28:30,119 --> 00:28:32,720
Speaker 1: the w boson is very short lived, but if you

623
00:28:32,800 --> 00:28:35,480
Speaker 1: decay and you use a photon instead, photons can live

624
00:28:35,520 --> 00:28:37,240
Speaker 1: for a very long time, and so some of these

625
00:28:37,240 --> 00:28:38,640
Speaker 1: decays can take much longer.

626
00:28:38,760 --> 00:28:41,320
Speaker 2: Wait, wait, wait, I feel like maybe there's two things here,

627
00:28:41,360 --> 00:28:44,080
Speaker 2: and I wonder if this is what's confusing Bill enough

628
00:28:44,120 --> 00:28:46,640
Speaker 2: for him to ask this question, which is, you know,

629
00:28:46,720 --> 00:28:49,680
Speaker 2: some things take a long time to decay, right, Like

630
00:28:49,720 --> 00:28:52,200
Speaker 2: they have a long half life, as we talked about

631
00:28:52,280 --> 00:28:54,960
Speaker 2: in the first third of the episode, like maybe a

632
00:28:54,960 --> 00:28:58,320
Speaker 2: potasting takes a billion years for half of them to decay, right,

633
00:28:58,480 --> 00:29:01,520
Speaker 2: because the probability of that is so small for it

634
00:29:01,560 --> 00:29:04,280
Speaker 2: to decay, So that there's that one thing the probability

635
00:29:04,320 --> 00:29:07,000
Speaker 2: over it to decay is small. Therefore the half life

636
00:29:07,080 --> 00:29:10,520
Speaker 2: is really long. But then when an individual potassium atom

637
00:29:10,720 --> 00:29:14,360
Speaker 2: actually decays, does that take an amount of time? And

638
00:29:14,480 --> 00:29:16,040
Speaker 2: it sounds like you said yes, but does it take

639
00:29:16,040 --> 00:29:18,440
Speaker 2: a different amount of time depending on the thing.

640
00:29:18,680 --> 00:29:21,000
Speaker 1: Yeah, so potassium atoms, they should all take the same

641
00:29:21,040 --> 00:29:23,840
Speaker 1: amount of time. But something else the decays in a

642
00:29:23,840 --> 00:29:26,600
Speaker 1: different wave. If it doesn't decay with a w boson,

643
00:29:26,640 --> 00:29:29,120
Speaker 1: for example, if it decays is through some other mechanism,

644
00:29:29,200 --> 00:29:30,640
Speaker 1: it can take longer or shorter.

645
00:29:30,960 --> 00:29:31,840
Speaker 2: What does that depend on?

646
00:29:31,880 --> 00:29:34,560
Speaker 1: Then it depends like on the mass of the particle involved.

647
00:29:34,600 --> 00:29:36,560
Speaker 1: The w boson, for example, is very heavy and so

648
00:29:36,600 --> 00:29:39,400
Speaker 1: it doesn't live for very long. It decays very very rapidly.

649
00:29:39,560 --> 00:29:42,080
Speaker 1: But if you decayed with another particle involved, you know,

650
00:29:42,120 --> 00:29:44,120
Speaker 1: for example, you didn't make a w boson, you made

651
00:29:44,120 --> 00:29:46,320
Speaker 1: a photon instead. Photons can live for a very long

652
00:29:46,360 --> 00:29:49,080
Speaker 1: time and so that decay process can take longer.

653
00:29:49,400 --> 00:29:51,560
Speaker 2: Is it possible for something to have like a short

654
00:29:51,600 --> 00:29:55,440
Speaker 2: half life but a long decay time and conversely like

655
00:29:55,840 --> 00:29:58,400
Speaker 2: something can have a long half life but a short

656
00:29:58,400 --> 00:29:58,920
Speaker 2: decay time.

657
00:29:59,040 --> 00:30:02,720
Speaker 1: Yeah, I don't think the twoth a connected at all.

658
00:30:02,840 --> 00:30:04,440
Speaker 1: If think, if you dug into it, there might be

659
00:30:04,480 --> 00:30:08,800
Speaker 1: some connections because the reason things decay quickly, is that

660
00:30:08,800 --> 00:30:11,240
Speaker 1: there was a high chance of decaying at any moment,

661
00:30:11,720 --> 00:30:15,000
Speaker 1: which probably means a stronger force, which might mean you

662
00:30:15,080 --> 00:30:17,760
Speaker 1: end up using gluons and photons rather than W and

663
00:30:17,840 --> 00:30:20,320
Speaker 1: Z bosons. So there might be some sort of loose

664
00:30:20,320 --> 00:30:21,280
Speaker 1: connection there.

665
00:30:21,160 --> 00:30:23,440
Speaker 2: All right, well, I guess. And then the last part

666
00:30:23,440 --> 00:30:27,680
Speaker 2: of Bill's question was are these times unmeasurably short? Have

667
00:30:27,800 --> 00:30:31,120
Speaker 2: we measured actually any of these decay times or are

668
00:30:31,120 --> 00:30:33,400
Speaker 2: they still beyond our technological reach.

669
00:30:33,720 --> 00:30:36,120
Speaker 1: Most of these things happen much faster than we could

670
00:30:36,160 --> 00:30:39,280
Speaker 1: actually measure, so we can't measure most of these decays

671
00:30:39,280 --> 00:30:42,440
Speaker 1: like to see them halfway. For example, you can see

672
00:30:42,480 --> 00:30:44,560
Speaker 1: them before, you can see them after. But as we

673
00:30:44,560 --> 00:30:47,320
Speaker 1: talked about in a recent episode about the fastest time slice,

674
00:30:47,400 --> 00:30:49,320
Speaker 1: and we're nowhere close to being able to measure things

675
00:30:49,320 --> 00:30:51,680
Speaker 1: like down to ten of the nights twenty four seconds.

676
00:30:51,480 --> 00:30:53,640
Speaker 2: Which is how fast you think these decays are happening,

677
00:30:53,760 --> 00:30:57,720
Speaker 2: like the actual the decay of the probability function. Yeah,

678
00:30:57,760 --> 00:31:01,360
Speaker 2: but what about bananas? Bananas? We can measure those pretty right.

679
00:31:02,240 --> 00:31:04,280
Speaker 1: Yeah, let's take days or weeks to decay, or in

680
00:31:04,280 --> 00:31:05,560
Speaker 1: your house, just minutes.

681
00:31:08,760 --> 00:31:12,080
Speaker 2: We are well within the bounds of our physical abilities.

682
00:31:13,480 --> 00:31:15,160
Speaker 1: It sounds like it's improving every day.

683
00:31:15,720 --> 00:31:15,920
Speaker 4: Yeah.

684
00:31:15,960 --> 00:31:18,160
Speaker 2: Yeah, he is getting bigger and so he's eating more.

685
00:31:18,840 --> 00:31:20,680
Speaker 1: I think there's a correlation there actually.

686
00:31:21,440 --> 00:31:23,360
Speaker 2: All right, well, thank you Bill for that great question.

687
00:31:23,600 --> 00:31:26,560
Speaker 2: Now let's get to our last question, and this one

688
00:31:26,960 --> 00:31:31,040
Speaker 2: is about black holes and whether things spiral into them

689
00:31:31,320 --> 00:31:34,400
Speaker 2: or whether they fall straight in sort of. We'll dig

690
00:31:34,400 --> 00:31:36,680
Speaker 2: into that, but first let's take another quick break.

691
00:31:49,200 --> 00:31:49,480
Speaker 3: All right.

692
00:31:49,520 --> 00:31:52,200
Speaker 2: We're answering listener questions here today, and our last question

693
00:31:52,440 --> 00:31:55,960
Speaker 2: is about black holes, and it comes from Julian from Brazil.

694
00:31:56,520 --> 00:31:58,080
Speaker 4: Hi, Daniel, My.

695
00:31:58,160 --> 00:32:02,160
Speaker 3: Question is about black holes. Does the matter closer to

696
00:32:02,200 --> 00:32:05,160
Speaker 3: the actual black hole spins faster than the matter that's

697
00:32:05,400 --> 00:32:08,200
Speaker 3: more distant from the center. I mean, is it more

698
00:32:08,280 --> 00:32:11,480
Speaker 3: like a galaxy where everything spins more or less at

699
00:32:11,520 --> 00:32:14,760
Speaker 3: the same speed because dark matter is holding everything together?

700
00:32:15,240 --> 00:32:18,080
Speaker 3: Or is it more like the solar system where mercury

701
00:32:18,240 --> 00:32:21,360
Speaker 3: spins around the sun? Why faster than neptune? That's it?

702
00:32:21,520 --> 00:32:23,760
Speaker 3: Big fan of the podcast, the books and everything.

703
00:32:23,840 --> 00:32:27,400
Speaker 2: Thanks by all right, interesting question here today. It's got

704
00:32:27,440 --> 00:32:31,040
Speaker 2: my head spinning a little bit. Is he asking how

705
00:32:31,160 --> 00:32:36,440
Speaker 2: fast things spin as they fall in or do they

706
00:32:36,440 --> 00:32:37,760
Speaker 2: spin faster as they fall in.

707
00:32:38,000 --> 00:32:40,440
Speaker 1: Yeah, I think he wants to know about the rotation

708
00:32:40,600 --> 00:32:43,360
Speaker 1: speed of the accretion disk, this disc of matter that's

709
00:32:43,360 --> 00:32:45,400
Speaker 1: like on deck to fall into the black hole. He's

710
00:32:45,440 --> 00:32:49,120
Speaker 1: wondering does it spin faster the outside or near the center.

711
00:32:49,480 --> 00:32:51,640
Speaker 1: And he's comparing that to his understanding of the Solar

712
00:32:51,640 --> 00:32:54,600
Speaker 1: System and the galaxy and those spinning systems, and he

713
00:32:54,640 --> 00:32:56,640
Speaker 1: wants to know, like which one is more.

714
00:32:56,520 --> 00:32:58,840
Speaker 2: Like the accretion disk, because I guess you know, he

715
00:32:58,920 --> 00:33:02,040
Speaker 2: mentions the Solar System and the planets, like the planets

716
00:33:02,040 --> 00:33:06,080
Speaker 2: around our Sun, they're all have different orbital speeds, right,

717
00:33:06,160 --> 00:33:07,920
Speaker 2: Like some take one hundred two hundred years to go

718
00:33:07,960 --> 00:33:09,720
Speaker 2: around the Sun, some take at less time.

719
00:33:09,840 --> 00:33:12,680
Speaker 1: Yeah, and not just orbital periods because they're going further,

720
00:33:13,000 --> 00:33:15,960
Speaker 1: but their actual like speed relative to the Sun is

721
00:33:16,080 --> 00:33:20,160
Speaker 1: different at different distances from the Sun. And that's also

722
00:33:20,280 --> 00:33:23,760
Speaker 1: true and really powerful and important for galaxies. Right, understanding

723
00:33:23,960 --> 00:33:26,160
Speaker 1: how stars are moving around the center of the galaxies,

724
00:33:26,200 --> 00:33:29,160
Speaker 1: how we discovered that dark matter was a thing. So

725
00:33:29,240 --> 00:33:31,520
Speaker 1: this is a really an important and interesting question.

726
00:33:31,560 --> 00:33:33,520
Speaker 2: Right And at the same time, like the planets are

727
00:33:33,560 --> 00:33:34,920
Speaker 2: spinning in place.

728
00:33:34,680 --> 00:33:37,200
Speaker 1: Too, right, Yeah, everything is spinning.

729
00:33:37,520 --> 00:33:40,040
Speaker 2: Yeah, that's a nice way to spin it all right,

730
00:33:40,080 --> 00:33:42,520
Speaker 2: So then I guess maybe step us through. What is

731
00:33:42,560 --> 00:33:44,520
Speaker 2: an accretion disk of a black hole?

732
00:33:44,600 --> 00:33:46,920
Speaker 1: Yeah, so an accretion disk is the stuff you see

733
00:33:47,160 --> 00:33:49,600
Speaker 1: sort of at the belt of the black hole. Right.

734
00:33:49,600 --> 00:33:52,040
Speaker 1: Most black holes are spinning and the stuff around them

735
00:33:52,400 --> 00:33:54,920
Speaker 1: is spinning. And that's because stuff doesn't just like fall

736
00:33:55,000 --> 00:33:57,080
Speaker 1: into a black hole. You might have a mental picture

737
00:33:57,120 --> 00:33:59,120
Speaker 1: of a black hole is like a giant space vacuum

738
00:33:59,200 --> 00:34:02,320
Speaker 1: sucking stuff up. But black holes just have gravity the

739
00:34:02,360 --> 00:34:05,040
Speaker 1: way anything else has gravity. Like you replace the Sun

740
00:34:05,120 --> 00:34:07,160
Speaker 1: with a black hole the same mass and the Earth's

741
00:34:07,200 --> 00:34:10,680
Speaker 1: orbit wouldn't change, wouldn't get like magically sucked in. And

742
00:34:10,800 --> 00:34:13,560
Speaker 1: things can orbit something with gravity and not fall in

743
00:34:13,600 --> 00:34:16,440
Speaker 1: the way the Earth orbits the Sun and doesn't fall

744
00:34:16,440 --> 00:34:18,640
Speaker 1: in the way the Sun orbits the center of the

745
00:34:18,640 --> 00:34:21,400
Speaker 1: galaxy and doesn't fall in. You can also orbit a

746
00:34:21,400 --> 00:34:24,600
Speaker 1: black hole and not fall in. So the accretion disc

747
00:34:24,680 --> 00:34:27,440
Speaker 1: is stuff that's near the black hole. It's come in

748
00:34:27,520 --> 00:34:30,040
Speaker 1: like at an angle, so it's whizzing around the black

749
00:34:30,040 --> 00:34:31,440
Speaker 1: hole before it falls in.

750
00:34:32,760 --> 00:34:34,600
Speaker 2: I feel like maybe we covered this in our book.

751
00:34:35,120 --> 00:34:37,719
Speaker 2: Frequently asked questions about the universe now available for sale,

752
00:34:37,920 --> 00:34:40,960
Speaker 2: But is the accretion disc of a black hole continuous

753
00:34:41,280 --> 00:34:43,319
Speaker 2: or does it only exist in the band, you know,

754
00:34:43,400 --> 00:34:46,640
Speaker 2: sort of like Saturn's rings. They don't go out there

755
00:34:46,640 --> 00:34:49,960
Speaker 2: into infinity. They sort of an extent to them.

756
00:34:50,040 --> 00:34:52,480
Speaker 1: There are definitely regions near a black hole where you

757
00:34:52,520 --> 00:34:54,800
Speaker 1: can be in a stable orbit, or regions where you can't,

758
00:34:54,920 --> 00:34:56,759
Speaker 1: Like if you get close enough to a black hole,

759
00:34:56,800 --> 00:34:59,399
Speaker 1: you're definitely just going to fall in and you're done,

760
00:34:59,520 --> 00:35:01,919
Speaker 1: unless you're a photon. So there's like a photon ring

761
00:35:02,320 --> 00:35:05,200
Speaker 1: where photons can orbit a black hole stabily, like where

762
00:35:05,239 --> 00:35:08,279
Speaker 1: if you shot a flashlight forwards, it would hit you

763
00:35:08,320 --> 00:35:10,400
Speaker 1: in the back of the head, for example. But stuff

764
00:35:10,440 --> 00:35:12,839
Speaker 1: with matter can't orbit there stable. It will just fall

765
00:35:12,840 --> 00:35:15,840
Speaker 1: towards the event horizon. So there's definitely like a region

766
00:35:16,120 --> 00:35:18,600
Speaker 1: near the black hole where you can't have any stable orbits,

767
00:35:18,640 --> 00:35:21,520
Speaker 1: and then regions further out where you could have stable orbits.

768
00:35:22,440 --> 00:35:24,600
Speaker 2: So maybe it does have an like an extent like

769
00:35:24,640 --> 00:35:26,240
Speaker 2: an outer limit in an inner limit.

770
00:35:26,440 --> 00:35:29,480
Speaker 1: It may, but there's an important difference between what's happening

771
00:35:29,520 --> 00:35:32,520
Speaker 1: in an accretion disk and what's happening with like planets

772
00:35:32,760 --> 00:35:35,520
Speaker 1: orbiting the Sun or the Sun orbiting the center of

773
00:35:35,560 --> 00:35:39,279
Speaker 1: the galaxy, and that's friction. Like in our orbit, we're

774
00:35:39,320 --> 00:35:41,640
Speaker 1: mostly not interacting with other stuff. We get like a

775
00:35:41,640 --> 00:35:43,680
Speaker 1: little bit of a tug from Jupiter now and then

776
00:35:43,760 --> 00:35:46,959
Speaker 1: and from Mars, but mostly we're alone in an orbit

777
00:35:47,000 --> 00:35:48,920
Speaker 1: and we're just orbiting the Sun, and the Sun is

778
00:35:49,040 --> 00:35:51,440
Speaker 1: orbiting the center of the galaxy, and it's mostly not

779
00:35:51,520 --> 00:35:54,959
Speaker 1: like bumping into stuff and losing energy, and so things

780
00:35:54,960 --> 00:35:57,279
Speaker 1: can be in stable orbits for billions of years. Right

781
00:35:57,320 --> 00:35:59,360
Speaker 1: the Earth has been going around the Sun for billions

782
00:35:59,400 --> 00:36:01,160
Speaker 1: of years. The Sun has been going around the center

783
00:36:01,160 --> 00:36:04,640
Speaker 1: of the galaxy all of that time, and that's pretty stable.

784
00:36:04,760 --> 00:36:07,520
Speaker 1: But an accretion disk is hot and nasty in a

785
00:36:07,640 --> 00:36:10,720
Speaker 1: very different way. There's a lot of interactions happening between

786
00:36:10,760 --> 00:36:12,239
Speaker 1: this stuff in the accretion disk.

787
00:36:12,360 --> 00:36:14,919
Speaker 2: Because I think, just like in our sun, you can

788
00:36:15,080 --> 00:36:17,719
Speaker 2: orbit a black hole for a long time, right, Like

789
00:36:17,760 --> 00:36:20,560
Speaker 2: you could you could be a planet with life when

790
00:36:20,600 --> 00:36:23,360
Speaker 2: it orbiting your black hole, and you think, like, and

791
00:36:23,440 --> 00:36:25,279
Speaker 2: that would be normal to you, Like instead of a sun,

792
00:36:25,280 --> 00:36:27,000
Speaker 2: you would have a dark circle in the sky.

793
00:36:27,280 --> 00:36:29,160
Speaker 1: Exactly. If you found a black hole that was all

794
00:36:29,200 --> 00:36:31,359
Speaker 1: by itself and didn't have an accretion disc, you could

795
00:36:31,440 --> 00:36:33,719
Speaker 1: put a planet there and it would orbit stabily and

796
00:36:33,880 --> 00:36:34,839
Speaker 1: be happy, no.

797
00:36:34,880 --> 00:36:37,560
Speaker 2: Problem, or even without an accretion disk, right, Like, if

798
00:36:37,600 --> 00:36:39,319
Speaker 2: you're maybe far enough away from it.

799
00:36:39,360 --> 00:36:41,600
Speaker 1: Yeah, if you're far enough away, then that's not a problem.

800
00:36:41,680 --> 00:36:44,040
Speaker 1: But in accretion disk, this stuff everywhere, and it's all

801
00:36:44,080 --> 00:36:47,520
Speaker 1: interacting and it's rubbing against itself. And that's why accretion

802
00:36:47,600 --> 00:36:50,879
Speaker 1: disks glow because they're hot, because they're bumping into each other,

803
00:36:50,880 --> 00:36:54,600
Speaker 1: they're moving fast. There's lots of energy exchange, so very

804
00:36:54,600 --> 00:36:56,839
Speaker 1: little stuff in the accretion disk is orbiting the way

805
00:36:56,840 --> 00:36:59,040
Speaker 1: our planet is orbiting or the Sun is orbiting the

806
00:36:59,040 --> 00:37:02,680
Speaker 1: center of the galaxy. Mostly it's spiraling in. So the

807
00:37:02,719 --> 00:37:05,680
Speaker 1: trajectory the dynamics of an accretion disc are very different

808
00:37:05,719 --> 00:37:08,200
Speaker 1: from the dynamics of the Solar system or the galaxy.

809
00:37:08,480 --> 00:37:11,120
Speaker 1: Almost nothing is moving in a circle or an ellipse.

810
00:37:11,239 --> 00:37:14,200
Speaker 1: Almost everything is moving in a spiral as it's losing

811
00:37:14,320 --> 00:37:16,040
Speaker 1: energy and falling in right.

812
00:37:16,040 --> 00:37:17,920
Speaker 2: Well, I think you said kind of the key word there,

813
00:37:17,920 --> 00:37:20,000
Speaker 2: which is friction, which is like, you know, you can

814
00:37:20,120 --> 00:37:21,920
Speaker 2: orbit the Sun or a black hole forever as long

815
00:37:21,960 --> 00:37:24,279
Speaker 2: as you're not losing energy. But once you start losing

816
00:37:24,360 --> 00:37:26,719
Speaker 2: energy because maybe things are bumping into you or you're

817
00:37:26,800 --> 00:37:30,360
Speaker 2: rubbing against other the space debris, then you're going to

818
00:37:30,440 --> 00:37:31,120
Speaker 2: start falling in.

819
00:37:31,360 --> 00:37:34,080
Speaker 1: Yeah, exactly. And the key concept here is angular momentum.

820
00:37:34,120 --> 00:37:36,040
Speaker 1: The thing that keeps the Earth in orbit around the

821
00:37:36,040 --> 00:37:37,759
Speaker 1: Sun and the Sun in orbit around the center of

822
00:37:37,760 --> 00:37:40,680
Speaker 1: the galaxy is its angular momentum. That's what keeps you going.

823
00:37:40,719 --> 00:37:43,600
Speaker 1: It makes a stable orbit. Things in the accretion disc

824
00:37:43,640 --> 00:37:45,279
Speaker 1: of the black hole will bump into each other, Like

825
00:37:45,280 --> 00:37:47,560
Speaker 1: how do you lose angular momentum? Something has to apply

826
00:37:47,600 --> 00:37:49,840
Speaker 1: a torque to you, and that's that other thing you

827
00:37:49,920 --> 00:37:52,680
Speaker 1: bumped into. So you knock something further away, and you

828
00:37:52,719 --> 00:37:55,400
Speaker 1: get knocked in closer to the accretion disk, and then

829
00:37:55,400 --> 00:37:58,040
Speaker 1: you start to fall in. So you actually gain energy, right,

830
00:37:58,120 --> 00:38:00,840
Speaker 1: you gain velocity. This is I think what Julian was

831
00:38:00,880 --> 00:38:03,319
Speaker 1: asking about. As you get closer to the black hole,

832
00:38:03,480 --> 00:38:07,000
Speaker 1: you've lost angular momentum. But now you're pointing towards the

833
00:38:07,000 --> 00:38:09,080
Speaker 1: core of the black hole. You're speeding up as you

834
00:38:09,120 --> 00:38:11,359
Speaker 1: come in, so you're getting faster. So you actually sort

835
00:38:11,400 --> 00:38:14,920
Speaker 1: of gain energy but lose angular momentum.

836
00:38:14,920 --> 00:38:17,440
Speaker 2: So you are spinning faster as you get closer.

837
00:38:17,640 --> 00:38:20,480
Speaker 1: You're moving fast, you have a higher velocity, but your

838
00:38:20,560 --> 00:38:23,640
Speaker 1: angular velocity is decreasing, You're not like whizzing around the

839
00:38:23,680 --> 00:38:26,080
Speaker 1: black hole as much. That's what was keeping you away

840
00:38:26,120 --> 00:38:28,480
Speaker 1: from the center, is that you were moving around it.

841
00:38:28,520 --> 00:38:30,719
Speaker 1: You're like missing the black hole. Like the reason the

842
00:38:30,719 --> 00:38:33,120
Speaker 1: Moon doesn't fall to the Earth is that it's enough

843
00:38:33,160 --> 00:38:35,680
Speaker 1: angular velocity to sort of miss the Earth even though

844
00:38:35,719 --> 00:38:37,959
Speaker 1: the Earth is pulling on it. But if you lose

845
00:38:38,000 --> 00:38:40,279
Speaker 1: that angular velocity, then the pull is just going to

846
00:38:40,320 --> 00:38:42,799
Speaker 1: pull you straight in towards the center, and it will

847
00:38:42,800 --> 00:38:45,040
Speaker 1: speed you up as you fall in the same way

848
00:38:45,080 --> 00:38:46,879
Speaker 1: that Like, if you drop a rock from the Moon

849
00:38:46,920 --> 00:38:48,840
Speaker 1: to the Earth and it falls in, it's going to

850
00:38:48,880 --> 00:38:50,799
Speaker 1: be going really fast. By the time it hits the

851
00:38:50,800 --> 00:38:52,960
Speaker 1: surface of the Earth. You're going to be going really

852
00:38:53,000 --> 00:38:54,800
Speaker 1: fast if you bump into a rock and the accretion

853
00:38:54,920 --> 00:38:56,479
Speaker 1: disk and head towards the black hole.

854
00:38:57,000 --> 00:38:59,919
Speaker 2: What did you slip on a banana near a black hole?

855
00:39:01,520 --> 00:39:02,880
Speaker 1: And then as you fall in you can blame it

856
00:39:02,880 --> 00:39:03,359
Speaker 1: on your son.

857
00:39:03,800 --> 00:39:09,320
Speaker 2: I told you, yeah, totally, not to cut the banana.

858
00:39:09,520 --> 00:39:11,600
Speaker 1: Are you telling me you cut bananas? I mean bananas

859
00:39:11,640 --> 00:39:14,239
Speaker 1: come with like a handy device. You can just peel

860
00:39:14,280 --> 00:39:16,000
Speaker 1: them and eat them. You don't need any utensils.

861
00:39:16,040 --> 00:39:17,520
Speaker 2: But yeah, but if you only want to eat half,

862
00:39:17,520 --> 00:39:19,719
Speaker 2: you can cut it, because otherwise you peel half and

863
00:39:19,760 --> 00:39:24,280
Speaker 2: then you got this hanging a peal that eventually looks close.

864
00:39:25,040 --> 00:39:26,680
Speaker 2: But if you cut a banana then it's clean.

865
00:39:26,719 --> 00:39:28,239
Speaker 1: I have this argument with my kids all the time.

866
00:39:28,239 --> 00:39:29,920
Speaker 1: They like to eat apples by cutting them, and I'm like,

867
00:39:29,960 --> 00:39:31,720
Speaker 1: you don't need to cut. You just hold in your hand.

868
00:39:32,320 --> 00:39:35,800
Speaker 1: You have teeth already. Like, it's beautiful, it's utensil free eating.

869
00:39:35,960 --> 00:39:38,080
Speaker 2: Sure, I mean that can say that about any kind

870
00:39:38,120 --> 00:39:40,280
Speaker 2: of eating. Dina, you can eat spaghetti without a fork

871
00:39:40,800 --> 00:39:44,959
Speaker 2: as well, why not.

872
00:39:44,480 --> 00:39:46,840
Speaker 1: They make this argument as well. They make this argument

873
00:39:46,840 --> 00:39:47,360
Speaker 1: as well.

874
00:39:47,560 --> 00:39:50,960
Speaker 2: Like, wow, dinner time must be really entertaining at your house.

875
00:39:53,440 --> 00:39:59,840
Speaker 2: Their facing a bull spaghetti. But anyways, black holes sort of.

876
00:40:00,000 --> 00:40:01,839
Speaker 2: I was like, you're saying that if you're far away

877
00:40:01,880 --> 00:40:03,759
Speaker 2: from the black hole and you start to fall in,

878
00:40:04,480 --> 00:40:06,719
Speaker 2: maybe you will start to spin faster, right, because the

879
00:40:06,760 --> 00:40:09,520
Speaker 2: stuff around the accretion in the accretion disk near the

880
00:40:09,520 --> 00:40:13,080
Speaker 2: black hole, that stuff is glowing and getting intense because

881
00:40:13,080 --> 00:40:15,000
Speaker 2: it is spinning so fast. Are you saying then that

882
00:40:15,080 --> 00:40:17,359
Speaker 2: once you fall into the black hole, then you slow down?

883
00:40:17,600 --> 00:40:20,080
Speaker 1: Well, I think that you're not spinning faster. As you

884
00:40:20,120 --> 00:40:23,040
Speaker 1: fall into the black hole, you're moving faster. So it's

885
00:40:23,080 --> 00:40:25,520
Speaker 1: a little bit of a nuance there between velocity and

886
00:40:25,600 --> 00:40:29,440
Speaker 1: angular velocity. Right, you're moving faster towards the center of

887
00:40:29,480 --> 00:40:31,680
Speaker 1: the black hole, but your angle relative to the black

888
00:40:31,680 --> 00:40:35,160
Speaker 1: hole is not changing anymore, and so you lost angler momentum.

889
00:40:35,160 --> 00:40:37,600
Speaker 1: You definitely have higher velocity, and that's why, as you say,

890
00:40:37,680 --> 00:40:40,320
Speaker 1: things glow right, these things are moving very very fast

891
00:40:40,360 --> 00:40:43,399
Speaker 1: and fast moving objects. If they have electric charge, they

892
00:40:43,400 --> 00:40:46,400
Speaker 1: will emit photons, and that's why the accretion disc of

893
00:40:46,440 --> 00:40:48,840
Speaker 1: black holes can be very very bright. That's why we

894
00:40:48,840 --> 00:40:50,960
Speaker 1: can see them. That picture of the black hole that's

895
00:40:50,960 --> 00:40:54,440
Speaker 1: so famous, Right, it's a ring around this black circle.

896
00:40:54,760 --> 00:40:57,160
Speaker 1: It's the accretion disc is what we're seeing. It's those

897
00:40:57,280 --> 00:41:00,560
Speaker 1: high speed particles as they fall in depens Once you

898
00:41:00,600 --> 00:41:03,480
Speaker 1: pass the event horizon, are you even going faster? That's

899
00:41:03,520 --> 00:41:06,640
Speaker 1: a question for quantum gravity. General relativity says depends on

900
00:41:06,680 --> 00:41:09,200
Speaker 1: the observer. If you're far away, then you'll never actually

901
00:41:09,200 --> 00:41:11,959
Speaker 1: see that person cross the event horizon because time slows down.

902
00:41:12,320 --> 00:41:15,279
Speaker 1: If you're that actual particle, you can measure your velocity

903
00:41:15,600 --> 00:41:17,759
Speaker 1: as you accelerate towards the singularity.

904
00:41:19,239 --> 00:41:21,560
Speaker 2: But I think we covered this in our book. Frequently

905
00:41:21,600 --> 00:41:24,440
Speaker 2: asked questions about the universe now for soil, for sue, yes,

906
00:41:25,560 --> 00:41:28,919
Speaker 2: that the accretioning disk is not sort of continuous down

907
00:41:28,960 --> 00:41:30,960
Speaker 2: to the black hole or even to the event horizon,

908
00:41:31,000 --> 00:41:34,440
Speaker 2: Like there's a gap right between the event horizon or

909
00:41:34,440 --> 00:41:36,520
Speaker 2: at least the shadow of the black hole and this

910
00:41:36,680 --> 00:41:37,359
Speaker 2: glowing disk.

911
00:41:37,560 --> 00:41:39,120
Speaker 1: Well, yeah, there's a gap where you can't have a

912
00:41:39,160 --> 00:41:42,400
Speaker 1: stable orbit, but you could still have stuff falling in actively.

913
00:41:42,640 --> 00:41:45,959
Speaker 1: Right So below, for example, the Photon ring, you can't

914
00:41:45,960 --> 00:41:49,520
Speaker 1: have anything orbiting that's outside the event horizon, but inside

915
00:41:49,560 --> 00:41:52,319
Speaker 1: the photon ring you can't have anything orbiting stabily there,

916
00:41:52,440 --> 00:41:54,560
Speaker 1: but you can still have stuff there. If it's falling

917
00:41:54,640 --> 00:41:58,399
Speaker 1: in actively and currently, then you could still see stuff there,

918
00:41:59,120 --> 00:42:00,400
Speaker 1: So it doesn't have to be empty.

919
00:42:00,840 --> 00:42:02,560
Speaker 2: There's stuff, But there is a little bit of a

920
00:42:02,600 --> 00:42:03,840
Speaker 2: gap there, right though.

921
00:42:03,880 --> 00:42:05,560
Speaker 1: It depends on the black hole, right if it's not

922
00:42:05,600 --> 00:42:08,000
Speaker 1: actively feeding, then yes, there will definitely be a gap there,

923
00:42:08,040 --> 00:42:10,879
Speaker 1: and you could imagine stable stuff orbiting further out from

924
00:42:10,880 --> 00:42:13,160
Speaker 1: the photon ring. But you know, if you dump like

925
00:42:13,200 --> 00:42:15,520
Speaker 1: a whole space ship full of gravy, for example, then

926
00:42:15,560 --> 00:42:19,040
Speaker 1: you can fill up that whole area with gravy particles briefly, right,

927
00:42:19,120 --> 00:42:20,880
Speaker 1: then they're all going to fall in. They can't stay

928
00:42:20,880 --> 00:42:22,360
Speaker 1: stably there in that gap.

929
00:42:22,640 --> 00:42:24,400
Speaker 2: Now, when you keep gravy in your house, do you

930
00:42:24,480 --> 00:42:25,440
Speaker 2: use utensils too?

931
00:42:26,560 --> 00:42:28,359
Speaker 1: We use a gravy boat and we just like pour

932
00:42:28,440 --> 00:42:29,200
Speaker 1: it all over the table.

933
00:42:29,320 --> 00:42:31,720
Speaker 2: Yeah, yeah, well you believe in the gravy boat. Okay,

934
00:42:31,760 --> 00:42:33,400
Speaker 2: I'm just trying to find out where your line is

935
00:42:33,600 --> 00:42:34,320
Speaker 2: for stability.

936
00:42:34,480 --> 00:42:35,719
Speaker 1: Super soaker is filled with gravy.

937
00:42:36,320 --> 00:42:38,120
Speaker 2: Gravy super soaker, Yeah, I just opened.

938
00:42:37,880 --> 00:42:39,680
Speaker 1: My mouth and the kids just shoot the gravy in.

939
00:42:39,920 --> 00:42:40,120
Speaker 4: You know.

940
00:42:42,160 --> 00:42:43,920
Speaker 2: That sounds like a lot more trouble than a spoon,

941
00:42:44,000 --> 00:42:45,920
Speaker 2: don't you, Because then you have to clean up. You

942
00:42:45,920 --> 00:42:47,120
Speaker 2: have to clean up the super soaker.

943
00:42:47,200 --> 00:42:49,080
Speaker 1: Yeah, well you got the fire hose afterwards. You know

944
00:42:49,080 --> 00:42:51,959
Speaker 1: it all cleans up pretty well. Tool.

945
00:42:52,000 --> 00:42:54,520
Speaker 2: That's another tool you need just to clean a super soaker.

946
00:42:54,960 --> 00:42:56,759
Speaker 1: Did you hear about that lady who made her entire

947
00:42:56,840 --> 00:42:58,879
Speaker 1: kitchen the inside of a washing machine so she could

948
00:42:58,880 --> 00:43:00,720
Speaker 1: just wash the whole kitchen but the press of a button.

949
00:43:00,880 --> 00:43:04,399
Speaker 2: I have not heard of this. Now, having a great idea,

950
00:43:04,840 --> 00:43:07,920
Speaker 2: isn't that like those public restrooms and parks do they

951
00:43:07,960 --> 00:43:10,680
Speaker 2: have in some cities where did you like just close

952
00:43:10,719 --> 00:43:13,320
Speaker 2: the door and then it turns into a washing machine

953
00:43:13,320 --> 00:43:13,640
Speaker 2: in there?

954
00:43:13,719 --> 00:43:17,839
Speaker 1: Yeah, exactly, great idea, And anybody with toddlers understands why

955
00:43:17,840 --> 00:43:18,680
Speaker 1: that's a good idea.

956
00:43:19,040 --> 00:43:20,319
Speaker 2: Just make your whole house that way.

957
00:43:20,480 --> 00:43:22,960
Speaker 1: Yeah exactly. It's just like make the whole plane out

958
00:43:22,960 --> 00:43:23,839
Speaker 1: of the black box, right.

959
00:43:24,040 --> 00:43:26,160
Speaker 2: Yeah, it'll clean itself up like a black hole and

960
00:43:26,239 --> 00:43:28,400
Speaker 2: as you clog it with too many too much gravy.

961
00:43:29,600 --> 00:43:32,440
Speaker 1: But people are really interested in studying the dynamics of

962
00:43:32,480 --> 00:43:35,960
Speaker 1: accretion disks because it tells us something about what's happening there. Like,

963
00:43:36,040 --> 00:43:39,040
Speaker 1: you can learn a lot about what's going on just

964
00:43:39,080 --> 00:43:41,480
Speaker 1: by looking at the velocity of stuff. Like one of

965
00:43:41,480 --> 00:43:43,920
Speaker 1: the ways that we know black holes exist is by

966
00:43:43,960 --> 00:43:46,840
Speaker 1: looking at stars orbiting them and seeing their velocity. We

967
00:43:46,840 --> 00:43:49,600
Speaker 1: can use that to measure the mass of the black hole,

968
00:43:49,680 --> 00:43:51,360
Speaker 1: Like the black hole the center of our galaxies is

969
00:43:51,360 --> 00:43:54,600
Speaker 1: a recent Nobel prize from studying the motion of stars

970
00:43:54,680 --> 00:43:57,840
Speaker 1: nearby that black hole. Their velocity tells us the mass.

971
00:43:58,040 --> 00:44:01,000
Speaker 1: It is. This incredibly powerful probe in the same way

972
00:44:01,040 --> 00:44:03,520
Speaker 1: that like, looking at the velocity of stars in the

973
00:44:03,520 --> 00:44:06,080
Speaker 1: galaxy told us how much mass there was because there

974
00:44:06,120 --> 00:44:08,439
Speaker 1: had to be mass to hold in all those high

975
00:44:08,440 --> 00:44:11,799
Speaker 1: speed stars, and so it's a really powerful way to

976
00:44:11,880 --> 00:44:13,680
Speaker 1: see things that you can't see directly.

977
00:44:13,920 --> 00:44:16,680
Speaker 2: All right, well, great question, thank you, Julian. And I

978
00:44:16,680 --> 00:44:20,200
Speaker 2: guess the basic answer for Julian is that, yeah, things

979
00:44:20,520 --> 00:44:23,120
Speaker 2: kind of spin at different speeds around a black hole,

980
00:44:23,600 --> 00:44:25,120
Speaker 2: just like they do around the Solar system.

981
00:44:25,320 --> 00:44:26,960
Speaker 1: Yeah, just like they do around the Solar system. Like

982
00:44:26,960 --> 00:44:28,960
Speaker 1: Mercury is going much faster than Earth, which is going

983
00:44:29,040 --> 00:44:31,759
Speaker 1: much faster than Saturn, which is going much faster than Neptune,

984
00:44:32,080 --> 00:44:33,799
Speaker 1: and so in accretion disc is a little bit more

985
00:44:33,840 --> 00:44:35,800
Speaker 1: like that, though there's a lot more bumping and grinding

986
00:44:35,840 --> 00:44:38,440
Speaker 1: going on in the accretion disk than in the Solar system.

987
00:44:38,560 --> 00:44:41,480
Speaker 2: Oh, you make it sound very sexy there, But it

988
00:44:41,600 --> 00:44:43,560
Speaker 2: sort of depends also on the mass, right, Like something

989
00:44:43,560 --> 00:44:45,560
Speaker 2: can be closed but moving slow, but something could be

990
00:44:45,840 --> 00:44:46,800
Speaker 2: far and moving fast.

991
00:44:46,920 --> 00:44:48,360
Speaker 1: There's going to be a lot of variation because in

992
00:44:48,440 --> 00:44:50,080
Speaker 1: decretion disc is a lot of chaos in it. But

993
00:44:50,160 --> 00:44:52,360
Speaker 1: in general, things will definitely be faster closer to the

994
00:44:52,360 --> 00:44:55,040
Speaker 1: black hole because they've fallen in that gravitational potential.

995
00:44:55,760 --> 00:44:57,960
Speaker 2: But within the accreasing disc there might be some things

996
00:44:58,000 --> 00:45:01,600
Speaker 2: moving faster than others. Right, yeah, all right, Well three

997
00:45:01,640 --> 00:45:05,520
Speaker 2: great questions, two of them about banana radiation. Boy, I

998
00:45:05,520 --> 00:45:08,200
Speaker 2: wonder if that de kay ratio is the ratio is

999
00:45:08,239 --> 00:45:11,360
Speaker 2: gonna be increasing over time. We're gonna hit one hundred

1000
00:45:11,360 --> 00:45:15,840
Speaker 2: percent full life banana topics on our listener questions.

1001
00:45:16,000 --> 00:45:17,439
Speaker 1: Tune in find out next time.

1002
00:45:17,920 --> 00:45:19,520
Speaker 2: I guess that could be easily hagged, Like you just

1003
00:45:19,560 --> 00:45:22,080
Speaker 2: have to coordinate with a couple of your friends, let's

1004
00:45:22,080 --> 00:45:25,520
Speaker 2: say six friends, and then just have you all ask

1005
00:45:25,560 --> 00:45:28,759
Speaker 2: a banana question at the same time. And then technically,

1006
00:45:28,840 --> 00:45:31,319
Speaker 2: because of Daniel's your rules, you would have to have

1007
00:45:32,320 --> 00:45:33,680
Speaker 2: a full banana episode.

1008
00:45:33,760 --> 00:45:35,160
Speaker 1: Oh my gosh, let's go for it.

1009
00:45:35,280 --> 00:45:37,320
Speaker 2: Oh man, that would be bananas.

1010
00:45:37,600 --> 00:45:37,880
Speaker 4: All right.

1011
00:45:37,920 --> 00:45:40,759
Speaker 2: Well, thanks again everyone who asked the question. We hope

1012
00:45:40,760 --> 00:45:44,680
Speaker 2: you enjoyed that. Thanks for joining us. See you next time.

1013
00:45:49,480 --> 00:45:52,360
Speaker 1: For more science and curiosity, come find us on social

1014
00:45:52,400 --> 00:45:56,320
Speaker 1: media where we answer questions and post videos. We're on Twitter,

1015
00:45:56,440 --> 00:46:00,040
Speaker 1: this word instant and now TikTok. Thanks for listening. I

1016
00:46:00,200 --> 00:46:02,840
Speaker 1: remember that. Daniel and Jorge Explain the Universe is a

1017
00:46:02,880 --> 00:46:07,480
Speaker 1: production of iHeartRadio. For more podcasts from iHeartRadio, visit the

1018
00:46:07,560 --> 00:46:11,680
Speaker 1: iHeartRadio app. Apple podcasts, or wherever you listen to your

1019
00:46:11,760 --> 00:46:12,520
Speaker 1: favorite shows.