1
00:00:08,480 --> 00:00:11,440
Speaker 1: Hey, Daniel, do people ever send you their personal theories

2
00:00:11,600 --> 00:00:14,720
Speaker 1: of the universe? Oh? Yeah, I get plenty of those.

3
00:00:15,560 --> 00:00:17,159
Speaker 1: What do you think they're hoping for? A lot of

4
00:00:17,200 --> 00:00:22,040
Speaker 1: them want to prove Einstein was wrong? Really, aim high?

5
00:00:22,040 --> 00:00:25,680
Speaker 1: I guess after all these years, aren't we convinced Einstein

6
00:00:25,800 --> 00:00:29,200
Speaker 1: was right? Actually, I'm pretty convinced Einstein was wrong. What

7
00:00:30,640 --> 00:00:32,960
Speaker 1: you think you know better than Einstein? I don't have

8
00:00:33,000 --> 00:00:35,640
Speaker 1: a better theory of the universe, but I'm pretty sure

9
00:00:35,720 --> 00:00:39,960
Speaker 1: his theory general relativity is not a correct description of nature. Well,

10
00:00:40,040 --> 00:00:41,840
Speaker 1: you should come up with your own theory then, Yeah,

11
00:00:41,880 --> 00:00:44,159
Speaker 1: and then I could send it to myself and then

12
00:00:44,200 --> 00:00:46,640
Speaker 1: you can answer it on the podcast. Done Nobel Prize

13
00:00:46,680 --> 00:01:05,280
Speaker 1: for the two of us. Hi am more Hammad, cartoonists

14
00:01:05,319 --> 00:01:08,200
Speaker 1: and the creator of PhD comics. Hi. I'm Daniel. I'm

15
00:01:08,240 --> 00:01:11,520
Speaker 1: a particle physicist, and I would love if somebody out

16
00:01:11,520 --> 00:01:15,520
Speaker 1: there proved Einstein wrong. Yeah, maybe even the ghost of Einstein,

17
00:01:15,760 --> 00:01:20,240
Speaker 1: Einstein's grandchildren, son of Einstein or daughter of Einstein. Einstein

18
00:01:20,280 --> 00:01:23,120
Speaker 1: had a pretty scandalous family situation, so I wouldn't be

19
00:01:23,120 --> 00:01:25,440
Speaker 1: surprised if some of his kids or grandkids are great

20
00:01:25,480 --> 00:01:28,120
Speaker 1: grandkids were a little grumpy at him. Well, they definitely

21
00:01:28,160 --> 00:01:31,040
Speaker 1: heard it a nice brand name. So I mean, can

22
00:01:31,040 --> 00:01:33,120
Speaker 1: you imagine going for a job and put an ice

23
00:01:33,240 --> 00:01:35,520
Speaker 1: and on your resume and people are like, yeah, he's

24
00:01:35,520 --> 00:01:37,959
Speaker 1: probably not or she's not, probably not smart enough, not

25
00:01:38,120 --> 00:01:40,120
Speaker 1: likely to happen, right, It's a lot of pressure. What

26
00:01:40,160 --> 00:01:42,080
Speaker 1: if you, like, want to be a basketball player in

27
00:01:42,120 --> 00:01:44,840
Speaker 1: your name is Einstein and they're like, get off the core, Einstein,

28
00:01:45,880 --> 00:01:49,080
Speaker 1: go back to your chalk board there. Yeah, exactly what

29
00:01:49,160 --> 00:01:50,680
Speaker 1: do they call it when an actor can only get

30
00:01:50,680 --> 00:01:53,040
Speaker 1: one kind of real type cast? Right? Like Einstein and

31
00:01:53,120 --> 00:01:55,320
Speaker 1: all of his generations are all going to be forced

32
00:01:55,320 --> 00:01:58,000
Speaker 1: to be doing fundamental physics. Right. I haven't seen a

33
00:01:58,000 --> 00:02:01,200
Speaker 1: lot of stand up comedians, right, Or are is name Einstein?

34
00:02:01,280 --> 00:02:03,800
Speaker 1: Well they probably changed their names, right, they have stage names,

35
00:02:03,840 --> 00:02:07,160
Speaker 1: you know, the comedian formerly known as Einstein. I guess

36
00:02:07,160 --> 00:02:09,960
Speaker 1: that would help them. But anyways, welcome to our podcast.

37
00:02:10,040 --> 00:02:12,920
Speaker 1: Daniel and Jorge explain the universe in production of I

38
00:02:13,040 --> 00:02:15,959
Speaker 1: Heart Radio, in which we make everybody out there and

39
00:02:16,120 --> 00:02:19,400
Speaker 1: Einstein by explaining to you everything that we do know

40
00:02:19,480 --> 00:02:23,320
Speaker 1: about our crazy, beautiful, hot and wet and weird universe

41
00:02:23,560 --> 00:02:26,920
Speaker 1: and everything that we don't yet understand from the tiniest

42
00:02:26,960 --> 00:02:29,120
Speaker 1: little bits of space and how they fit together to

43
00:02:29,160 --> 00:02:33,120
Speaker 1: make this incredible, emergent, bonkers beautiful world, to the vast

44
00:02:33,360 --> 00:02:35,720
Speaker 1: nature of the cosmos. How far does it go on?

45
00:02:35,880 --> 00:02:38,120
Speaker 1: What's out past there? Will we ever see it? We

46
00:02:38,200 --> 00:02:41,520
Speaker 1: wrap up all those questions and explain them to you. Yeah,

47
00:02:41,560 --> 00:02:45,400
Speaker 1: because it is a vast universe full of intricate secrets

48
00:02:45,440 --> 00:02:48,799
Speaker 1: and lots of wonders for us discover hiding and plain

49
00:02:48,880 --> 00:02:52,560
Speaker 1: site sometimes right even around our own neighborhood. It is exactly.

50
00:02:52,680 --> 00:02:55,400
Speaker 1: I look at the universe like the biggest murder mystery

51
00:02:55,440 --> 00:02:58,200
Speaker 1: or the grandest detective novel ever written. It's like a

52
00:02:58,240 --> 00:03:01,040
Speaker 1: big puzzle figuring out how does it work. We're gathering

53
00:03:01,120 --> 00:03:03,480
Speaker 1: clues and trying to narrow down and figure out, like

54
00:03:03,760 --> 00:03:06,280
Speaker 1: what really makes the universe tick? What does it have

55
00:03:06,360 --> 00:03:08,480
Speaker 1: to be a murder mystery? Daniel, I feel like you

56
00:03:08,600 --> 00:03:11,360
Speaker 1: just went kind of dark there, like like somebody had

57
00:03:11,400 --> 00:03:13,600
Speaker 1: to die to make the universe. Well, you know, the

58
00:03:13,639 --> 00:03:17,399
Speaker 1: universe is going to kill you, Jorge. I'm sure it's

59
00:03:17,400 --> 00:03:21,760
Speaker 1: not the universe itself, but maybe my eating habits. Well,

60
00:03:21,800 --> 00:03:23,600
Speaker 1: I just think it adds some drama, you know, it's

61
00:03:23,600 --> 00:03:25,679
Speaker 1: always more fun to work on a mystery if there's

62
00:03:25,720 --> 00:03:27,959
Speaker 1: a body involved, I suppose, I don't know. That's why

63
00:03:27,960 --> 00:03:30,840
Speaker 1: there's that whole genre of murder mysteries, right, It's not like,

64
00:03:31,120 --> 00:03:34,240
Speaker 1: you know, who got gently tapped on the head in

65
00:03:34,280 --> 00:03:36,800
Speaker 1: the library with the candlestick. You know, it's like who

66
00:03:36,840 --> 00:03:39,440
Speaker 1: got killed? So, yeah, this is a big mystery. We

67
00:03:39,480 --> 00:03:42,560
Speaker 1: want to understand what is the fundamental nature of the universe,

68
00:03:42,600 --> 00:03:44,800
Speaker 1: what are the rules by which it runs? How can

69
00:03:44,840 --> 00:03:47,360
Speaker 1: we figure that out? And frankly, I'm amazed that we

70
00:03:47,480 --> 00:03:49,840
Speaker 1: really made any progress at all. Yeah. I guess if

71
00:03:49,880 --> 00:03:51,960
Speaker 1: the mystery was just word that I put my reading glasses,

72
00:03:52,520 --> 00:03:55,480
Speaker 1: that wouldn't attract a lot of viewers there, or physicists,

73
00:03:55,640 --> 00:03:59,400
Speaker 1: to be honest, Yeah, exactly, or true crime novelists named Einstein.

74
00:03:59,560 --> 00:04:01,840
Speaker 1: All right, we like to talk about all the great

75
00:04:01,880 --> 00:04:03,560
Speaker 1: mysteries out there on the universe, and also we like

76
00:04:03,600 --> 00:04:06,800
Speaker 1: to talk about what scientists are doing to uncover those

77
00:04:06,800 --> 00:04:09,480
Speaker 1: secrets and figure out what's really going on, because there

78
00:04:09,520 --> 00:04:13,280
Speaker 1: are a lot of interesting projects and interesting science experiments

79
00:04:13,280 --> 00:04:16,760
Speaker 1: going on right now as we speak, trying to peer

80
00:04:17,160 --> 00:04:20,760
Speaker 1: further into the universe and closer to the very nature

81
00:04:20,800 --> 00:04:23,960
Speaker 1: of matter. That's right, because even though folks like Einstein

82
00:04:24,040 --> 00:04:27,559
Speaker 1: gave us a beautiful glimpse into how the universe might work,

83
00:04:27,880 --> 00:04:31,279
Speaker 1: we are still figuring out whether his vision is correct

84
00:04:31,720 --> 00:04:35,080
Speaker 1: or not, whether it describes the way the universe actually works,

85
00:04:35,400 --> 00:04:38,599
Speaker 1: or if it's just like a very effective approximation which

86
00:04:38,680 --> 00:04:41,359
Speaker 1: from some point of view seems to be successful in

87
00:04:41,440 --> 00:04:44,800
Speaker 1: predicting what happens in weird situations. Yeah, and so you're

88
00:04:44,800 --> 00:04:48,600
Speaker 1: convinced that Eisen is wrong, you said earlier, like you're

89
00:04:48,640 --> 00:04:50,719
Speaker 1: pretty sure he's wrong, or you think he's wrong. I

90
00:04:50,720 --> 00:04:52,840
Speaker 1: think he's got to be wrong. I mean, there's no

91
00:04:52,920 --> 00:04:56,799
Speaker 1: way general relativity is correct. Why not, Well, it flies

92
00:04:56,839 --> 00:04:59,279
Speaker 1: in the face of the nature of the universe as

93
00:04:59,320 --> 00:05:02,960
Speaker 1: we know it. We know that the universe is quantum mechanical.

94
00:05:03,360 --> 00:05:07,000
Speaker 1: We know that nothing is smooth and continuous. But general

95
00:05:07,040 --> 00:05:10,560
Speaker 1: relativity assumes that the universe is smooth, it's continuous, that

96
00:05:10,600 --> 00:05:13,760
Speaker 1: you can like slice up space and time into infinitely

97
00:05:13,839 --> 00:05:17,440
Speaker 1: small pieces, that you can know everything about the configuration

98
00:05:17,640 --> 00:05:21,200
Speaker 1: of particles, for example. It just ignores the fundamental nature

99
00:05:21,200 --> 00:05:23,200
Speaker 1: of the universe that's been revealed to us over the

100
00:05:23,279 --> 00:05:26,599
Speaker 1: last hundred years. And that's why it breaks down. For example,

101
00:05:26,640 --> 00:05:28,719
Speaker 1: we have singularities at the hearts of black holes and

102
00:05:28,720 --> 00:05:31,599
Speaker 1: at the beginning of the universe. Those singularities reflect a

103
00:05:31,640 --> 00:05:34,920
Speaker 1: failure of the theory. So it just can't be right,

104
00:05:35,000 --> 00:05:37,720
Speaker 1: and yet it works, so darn well, well you don't

105
00:05:37,720 --> 00:05:39,920
Speaker 1: think it works. But maybe there is a singularity. I

106
00:05:39,960 --> 00:05:42,080
Speaker 1: don't know, isn't that possible? Well, we talked about this

107
00:05:42,120 --> 00:05:45,200
Speaker 1: in our fun episode about singularities. But singularity is like

108
00:05:45,200 --> 00:05:48,640
Speaker 1: a mathematical oddity. It's like an infinity. It's a failure.

109
00:05:48,640 --> 00:05:50,360
Speaker 1: It's like when the theory is going I don't know,

110
00:05:50,920 --> 00:05:53,360
Speaker 1: you know, it's not a real prediction, Like you can't

111
00:05:53,440 --> 00:05:58,520
Speaker 1: actually have infinite density. It's nonsensical. It's like an infinite universe,

112
00:05:58,760 --> 00:06:01,240
Speaker 1: which I here used to for it as a theory.

113
00:06:01,520 --> 00:06:04,720
Speaker 1: That's true, and it certainly could be that weird mathematical

114
00:06:04,800 --> 00:06:08,400
Speaker 1: features of the universe that we dismiss as artifacts could

115
00:06:08,440 --> 00:06:10,640
Speaker 1: actually be real. Right, It wouldn't be the first time

116
00:06:10,680 --> 00:06:12,880
Speaker 1: that had happened. But it seems to me like a failure.

117
00:06:12,960 --> 00:06:15,880
Speaker 1: And also it seems to me impossible to reconcile general

118
00:06:15,920 --> 00:06:19,520
Speaker 1: relativities view of the universe as smooth and continuous with

119
00:06:19,600 --> 00:06:22,279
Speaker 1: this quantum mechanical nature of the universe. We see that

120
00:06:22,360 --> 00:06:25,560
Speaker 1: it's discreet, we see that there are smallest bits. We

121
00:06:25,640 --> 00:06:28,400
Speaker 1: see that there is limited information. So we're desperate to

122
00:06:28,440 --> 00:06:31,240
Speaker 1: know the true story of the universe, how it actually works.

123
00:06:31,360 --> 00:06:34,159
Speaker 1: But to do that we need to see Einstein's theory fail.

124
00:06:34,279 --> 00:06:36,560
Speaker 1: We need to find a place where it's wrong. Yeah,

125
00:06:36,600 --> 00:06:38,920
Speaker 1: and that's really hard because so far as you said,

126
00:06:39,000 --> 00:06:42,320
Speaker 1: Einstein's theory, it's pretty good. It's past every test with

127
00:06:42,480 --> 00:06:45,239
Speaker 1: flying colors. It's got an A plus plus plus plus

128
00:06:45,279 --> 00:06:49,520
Speaker 1: plus plus. Like nobody's ever seen general relativity get anything wrong.

129
00:06:49,839 --> 00:06:53,560
Speaker 1: No matter what configuration of matter or weird effects you study,

130
00:06:53,960 --> 00:06:57,600
Speaker 1: or crazy intense things going on in the distance universe

131
00:06:57,640 --> 00:07:02,200
Speaker 1: like black holes colliding, general activity gets its spot on. Yeah,

132
00:07:02,320 --> 00:07:04,280
Speaker 1: and so there's a big question of whether or not

133
00:07:04,360 --> 00:07:08,760
Speaker 1: Einstein's theories are ultimately correct or not. And there is

134
00:07:08,800 --> 00:07:12,120
Speaker 1: one experiment right now, right above you will most likely

135
00:07:12,360 --> 00:07:15,600
Speaker 1: trying to figure that out. That's right. We physicist her

136
00:07:15,680 --> 00:07:19,200
Speaker 1: inventing more and more crazy scenarios to try to test

137
00:07:19,240 --> 00:07:22,720
Speaker 1: the details of these predictions of general relativity, hoping to

138
00:07:22,760 --> 00:07:26,000
Speaker 1: get it wrong, hoping to find a scenario where Einstein's

139
00:07:26,040 --> 00:07:28,880
Speaker 1: theory fails and forces us to come up with another theory,

140
00:07:28,960 --> 00:07:31,000
Speaker 1: or like gives us a clue as to how to

141
00:07:31,160 --> 00:07:33,960
Speaker 1: formulate that next theory. So today on the podcast we'll

142
00:07:34,000 --> 00:07:44,800
Speaker 1: be talking about what is frame dragging? I have to say, Daniel,

143
00:07:44,880 --> 00:07:47,200
Speaker 1: it feels like the disappointing title after all that build up.

144
00:07:47,240 --> 00:07:49,360
Speaker 1: I felt like we should have, you know, probing the

145
00:07:49,400 --> 00:07:52,680
Speaker 1: mysteries of the nature of space and time, But no,

146
00:07:53,040 --> 00:07:55,520
Speaker 1: we're going with but what is frame dragging? Well, that's

147
00:07:55,560 --> 00:07:58,680
Speaker 1: because frame dragging is one of the mysteries of space

148
00:07:58,720 --> 00:08:01,640
Speaker 1: and time. It's one of these bizarre effects predicted by

149
00:08:01,760 --> 00:08:04,280
Speaker 1: general relativity that people go out to see, like is

150
00:08:04,360 --> 00:08:07,560
Speaker 1: this actually real or is it just a mathematical artifact

151
00:08:07,840 --> 00:08:10,320
Speaker 1: or was Einstein wrong? Or it could just be that

152
00:08:10,360 --> 00:08:12,920
Speaker 1: you're taking a picture frame and dragging it across the floor.

153
00:08:13,320 --> 00:08:15,880
Speaker 1: It could go either way. Yeah, it doesn't really conjure

154
00:08:15,960 --> 00:08:18,800
Speaker 1: up the gravity of the situation if you ask me.

155
00:08:18,960 --> 00:08:21,800
Speaker 1: But coincidentally does have to do with gravity, right, and

156
00:08:22,040 --> 00:08:24,600
Speaker 1: I signed theory about how it all works. Yeah, and

157
00:08:24,720 --> 00:08:28,600
Speaker 1: reference frames like this idea of where you put your axes,

158
00:08:28,680 --> 00:08:30,880
Speaker 1: your X, Y and z, and how you measure your

159
00:08:30,920 --> 00:08:35,360
Speaker 1: position and your velocity is absolutely fundamentally central to the

160
00:08:35,400 --> 00:08:38,920
Speaker 1: whole concept of relativity, and so you know that gives

161
00:08:38,920 --> 00:08:40,839
Speaker 1: you clues to what it might be about. And I

162
00:08:40,880 --> 00:08:43,240
Speaker 1: think this is a super fun topic and I especially

163
00:08:43,240 --> 00:08:45,920
Speaker 1: hope that it's being enjoyed by one particular listener out

164
00:08:45,960 --> 00:08:49,240
Speaker 1: there from the Netherlands. He wrote to us last week

165
00:08:49,280 --> 00:08:51,800
Speaker 1: and he said that he really liked our podcast, but

166
00:08:52,320 --> 00:08:54,840
Speaker 1: that it had led to more than one occasion in

167
00:08:54,840 --> 00:08:58,120
Speaker 1: which he burned dinner. Oh no, well, out of frustration

168
00:08:58,240 --> 00:09:01,600
Speaker 1: or out of just not paying attention. Apparently he listened

169
00:09:01,600 --> 00:09:03,680
Speaker 1: to our podcast while he's cooking, and when things get

170
00:09:03,760 --> 00:09:07,040
Speaker 1: really complicated or interesting, he ignores what's on the stove

171
00:09:07,320 --> 00:09:10,600
Speaker 1: and things good things go up in flames. Wow, I

172
00:09:10,600 --> 00:09:13,480
Speaker 1: feel like we're destroying this person's family life here, if

173
00:09:13,520 --> 00:09:16,360
Speaker 1: not his actuate home. Yeah. He also said that his

174
00:09:16,440 --> 00:09:19,520
Speaker 1: kids know not to ask him anything or for anything

175
00:09:19,559 --> 00:09:22,400
Speaker 1: when he's listening to the podcast, because he'll just ignore them.

176
00:09:22,559 --> 00:09:24,839
Speaker 1: He or she should invite their kids to listen with

177
00:09:25,200 --> 00:09:30,400
Speaker 1: him her which kid doesn't want to know about frame dragging. Yeah,

178
00:09:30,480 --> 00:09:32,800
Speaker 1: so pay attention to the podcast, learn the secrets of

179
00:09:32,800 --> 00:09:35,880
Speaker 1: the universe, but also don't burn your dinner. Sorry, flipped

180
00:09:35,880 --> 00:09:39,559
Speaker 1: the chicken right now before it gets Yeah, let's pause

181
00:09:39,720 --> 00:09:41,719
Speaker 1: so that he's can finish the dinner. All right, Well,

182
00:09:41,760 --> 00:09:44,720
Speaker 1: this is an interesting question, and so as usual we

183
00:09:44,720 --> 00:09:47,080
Speaker 1: were wondering how many people out there had even heard

184
00:09:47,080 --> 00:09:50,120
Speaker 1: of this question and what it might mean or even

185
00:09:50,160 --> 00:09:52,679
Speaker 1: have an answer. So as usual, Daniel went out there

186
00:09:52,760 --> 00:09:56,240
Speaker 1: and ask people on the internet what is frame dragging?

187
00:09:56,440 --> 00:09:59,040
Speaker 1: So thanks to everybody who was willing to play along.

188
00:09:59,280 --> 00:10:01,960
Speaker 1: And if you have listened to the podcast and chuckle

189
00:10:02,000 --> 00:10:05,040
Speaker 1: along with these answers but never contributed your own, please

190
00:10:05,320 --> 00:10:08,160
Speaker 1: write to me two questions at Daniel and Jorge dot

191
00:10:08,240 --> 00:10:11,840
Speaker 1: com and volunteer. I promise it's fun. Here's what people

192
00:10:11,880 --> 00:10:14,760
Speaker 1: had to say. I'm going to guess that it has

193
00:10:14,800 --> 00:10:20,600
Speaker 1: something to do with photography, maybe photographing of planets in

194
00:10:20,600 --> 00:10:23,920
Speaker 1: a three dimensional space where we can only view them

195
00:10:23,920 --> 00:10:28,800
Speaker 1: in a two dimensional aspect. We take enough pictures of

196
00:10:28,840 --> 00:10:32,440
Speaker 1: the two dimensional aspects to drag them together to create

197
00:10:32,440 --> 00:10:36,520
Speaker 1: a three dimensional picture. Frame dragging is when it's moving

198
00:10:36,600 --> 00:10:41,280
Speaker 1: day and none of your friends show up to help. Um.

199
00:10:41,800 --> 00:10:47,760
Speaker 1: Frame dragging from physics point of view, UM, I don't know.

200
00:10:48,520 --> 00:10:54,440
Speaker 1: I have no idea frame dragging. UM, nothing all right.

201
00:10:54,920 --> 00:10:57,280
Speaker 1: Not a lot of people seem to have a good

202
00:10:57,320 --> 00:10:59,719
Speaker 1: idea here, like the one who said it's moving day

203
00:10:59,720 --> 00:11:02,720
Speaker 1: and none of your friends want to heppy move drag

204
00:11:02,760 --> 00:11:05,839
Speaker 1: your art frames around. Yeah, that's a great one. Should

205
00:11:05,960 --> 00:11:10,000
Speaker 1: ordered more pizza man, sorry, or you know, hired verse

206
00:11:10,160 --> 00:11:14,000
Speaker 1: perhaps so. Yeah, it's a pretty interesting question because it

207
00:11:14,040 --> 00:11:16,640
Speaker 1: doesn't sound physics ee, but I'm guessing it has something

208
00:11:16,720 --> 00:11:20,240
Speaker 1: to do with maybe like frames of reference or coordinate

209
00:11:20,280 --> 00:11:23,520
Speaker 1: systems or something like that. Exactly. It has to do

210
00:11:23,640 --> 00:11:27,640
Speaker 1: with a really bizarre prediction of general relativity. Remember that

211
00:11:27,720 --> 00:11:33,079
Speaker 1: general relativity is Einstein's theory of gravity, replaced Newton's theory.

212
00:11:33,400 --> 00:11:36,920
Speaker 1: Newton says two objects with mass will pull on each other,

213
00:11:36,960 --> 00:11:39,800
Speaker 1: that gravity is a force, but Einstein tells us that

214
00:11:39,840 --> 00:11:42,600
Speaker 1: gravity shouldn't be seen as a force. It's actually just

215
00:11:42,679 --> 00:11:45,720
Speaker 1: due to the fact that space and time curve around

216
00:11:45,800 --> 00:11:48,800
Speaker 1: massive objects. And if you can't see those curves, like

217
00:11:48,840 --> 00:11:51,800
Speaker 1: we can't detect them directly, then things will move in

218
00:11:51,800 --> 00:11:54,640
Speaker 1: a surprising way, and they move as if they were

219
00:11:54,760 --> 00:11:57,880
Speaker 1: under some force. And that's what gravity is. It's the

220
00:11:57,920 --> 00:12:01,560
Speaker 1: effect of the curvature of space time itself. Most of

221
00:12:01,559 --> 00:12:04,320
Speaker 1: the time those two things totally agree, Like you could

222
00:12:04,320 --> 00:12:06,880
Speaker 1: treat gravity as a force like Newton did, or you

223
00:12:06,880 --> 00:12:09,200
Speaker 1: could treat gravity is the mending of space time like

224
00:12:09,240 --> 00:12:11,880
Speaker 1: Einstein does. It doesn't really change the way the Earth

225
00:12:11,880 --> 00:12:14,600
Speaker 1: moves around the Sun, for example. But there are some

226
00:12:14,679 --> 00:12:18,000
Speaker 1: cases where they disagree, and that lets us probe Einstein's

227
00:12:18,000 --> 00:12:21,040
Speaker 1: theory as different from Newton's theory. Really, I thought it

228
00:12:21,080 --> 00:12:23,800
Speaker 1: was sort of like mathematically burned in that it was

229
00:12:23,840 --> 00:12:26,560
Speaker 1: the same thing. But no, there are exceptions. No, they're

230
00:12:26,600 --> 00:12:30,000
Speaker 1: fundamentally different ways of seeing the universe, and they give

231
00:12:30,040 --> 00:12:33,640
Speaker 1: different predictions in some cases, and almost every case they don't,

232
00:12:33,679 --> 00:12:36,720
Speaker 1: which is why Newton's theory worked so well. Right, Newton

233
00:12:36,840 --> 00:12:39,080
Speaker 1: got a lot of stuff right because for the most

234
00:12:39,120 --> 00:12:41,680
Speaker 1: part his theory is correct, and like that's a lesson

235
00:12:42,160 --> 00:12:45,240
Speaker 1: getting a bunch of experiments right. And like nailing predictions

236
00:12:45,480 --> 00:12:48,199
Speaker 1: for hundreds of years in a row doesn't mean that

237
00:12:48,240 --> 00:12:51,120
Speaker 1: your theory is fundamentally true. It doesn't mean that it's

238
00:12:51,120 --> 00:12:54,880
Speaker 1: an actual description of nature. It just means the experimentalists

239
00:12:54,880 --> 00:12:57,440
Speaker 1: having come up with a way to break your idea. Yet. Yeah,

240
00:12:57,520 --> 00:12:59,560
Speaker 1: and I imagine for Einstein it was a little bit

241
00:12:59,640 --> 00:13:02,480
Speaker 1: like it is now for us. With him, and that

242
00:13:02,600 --> 00:13:05,040
Speaker 1: you know, at the time, Newton was like the eyesight

243
00:13:05,440 --> 00:13:07,560
Speaker 1: of his day. And for him to be like I

244
00:13:07,559 --> 00:13:09,880
Speaker 1: think Newton's wrong, people were like, what do you think

245
00:13:09,920 --> 00:13:12,240
Speaker 1: you're smarter than Newton or for sure? And remember that

246
00:13:12,280 --> 00:13:15,160
Speaker 1: Einstein is further in time from Newton than we are

247
00:13:15,240 --> 00:13:17,880
Speaker 1: from Einstein. So I think Newton was probably like an

248
00:13:17,880 --> 00:13:21,840
Speaker 1: even grander, you know, person in the history of science

249
00:13:21,920 --> 00:13:24,000
Speaker 1: due to the passage of time, like his ideas had

250
00:13:24,000 --> 00:13:27,040
Speaker 1: stood longer, and whereas Einstein, like, you know, you can

251
00:13:27,040 --> 00:13:28,600
Speaker 1: see movies of the guy, you know, he's like a

252
00:13:28,679 --> 00:13:31,679
Speaker 1: real person. Well, there are the effects of internet relativity,

253
00:13:31,760 --> 00:13:35,600
Speaker 1: which you know makes time seem go faster, alright, So

254
00:13:35,640 --> 00:13:39,920
Speaker 1: there are instances where Einstein's theory of special relativity is

255
00:13:39,960 --> 00:13:42,839
Speaker 1: different than Newton's, and so we can test whether or

256
00:13:42,880 --> 00:13:45,480
Speaker 1: not the theories are correct exactly. And it really comes

257
00:13:45,520 --> 00:13:49,440
Speaker 1: down to things spinning. Like for Newton, it doesn't really

258
00:13:49,480 --> 00:13:52,680
Speaker 1: matter if the Earth is spinning. It's gravitational pull on

259
00:13:52,679 --> 00:13:55,400
Speaker 1: the Moon is the same. Like for Newton, the only

260
00:13:55,520 --> 00:13:58,400
Speaker 1: thing that gravity depends on are the masses of the

261
00:13:58,400 --> 00:14:01,280
Speaker 1: two objects and their relative stance. If you know Newton's

262
00:14:01,280 --> 00:14:04,920
Speaker 1: equation g mm over our squared. There's no factor in

263
00:14:04,960 --> 00:14:07,200
Speaker 1: there that can be influenced by the fact that the

264
00:14:07,200 --> 00:14:10,480
Speaker 1: Earth is spinning. It's irrelevant because like the configuration of

265
00:14:10,520 --> 00:14:13,120
Speaker 1: the mass doesn't actually change. Right, you have a perfect

266
00:14:13,120 --> 00:14:16,880
Speaker 1: sphere and you spin, it doesn't change the distance between

267
00:14:16,960 --> 00:14:20,600
Speaker 1: any of the objects. But for Einstein's theory it does matter. Right,

268
00:14:20,640 --> 00:14:22,640
Speaker 1: But as long as the I guess the center of

269
00:14:22,680 --> 00:14:26,080
Speaker 1: mass of the Earth is kind of onund the spin access, right. Yeah,

270
00:14:26,120 --> 00:14:28,720
Speaker 1: if you have a perfect sphere and it's spinning around

271
00:14:28,760 --> 00:14:32,600
Speaker 1: its center, then it's gravity is totally unaffected by its spin,

272
00:14:32,800 --> 00:14:35,920
Speaker 1: according to Newton, because the only thing that Newton cares

273
00:14:35,960 --> 00:14:39,320
Speaker 1: about is the relative distance between two little bits of mass,

274
00:14:39,320 --> 00:14:42,000
Speaker 1: and so if that's not changing, then the gravity shouldn't

275
00:14:42,080 --> 00:14:44,800
Speaker 1: change at all, right, and specifically like between the center

276
00:14:44,840 --> 00:14:47,000
Speaker 1: of masses of the two things, Right, that's the only

277
00:14:47,000 --> 00:14:49,360
Speaker 1: thing that counts for Newton. Yeah, for Newton, that's all

278
00:14:49,360 --> 00:14:52,280
Speaker 1: that counts. You can treat the Earth, for example, as

279
00:14:52,320 --> 00:14:54,960
Speaker 1: if it was a point particle with the same mass,

280
00:14:55,160 --> 00:14:57,600
Speaker 1: and you put that point particle at the center of mass,

281
00:14:57,760 --> 00:14:59,760
Speaker 1: and all the other effects of some things being closer

282
00:14:59,760 --> 00:15:02,320
Speaker 1: in some things being further away cancel out which is

283
00:15:02,320 --> 00:15:04,960
Speaker 1: a pretty cool, nice simplification. It makes a lot of

284
00:15:04,960 --> 00:15:08,560
Speaker 1: physics much easier to do. But Einstein's special relativity is

285
00:15:08,600 --> 00:15:11,520
Speaker 1: not the same. Einstein's theory of general relativity says that

286
00:15:11,640 --> 00:15:16,119
Speaker 1: spin does matter, that the way an object spins affects

287
00:15:16,160 --> 00:15:19,240
Speaker 1: the way that it bends space and time, and that

288
00:15:19,280 --> 00:15:23,200
Speaker 1: will change the gravitational effect on objects moving around a

289
00:15:23,280 --> 00:15:26,320
Speaker 1: spinning Earth versus a non spinning Earth, and we can

290
00:15:26,320 --> 00:15:29,200
Speaker 1: do experiments to see if that's correct. Wait, what you

291
00:15:29,240 --> 00:15:33,520
Speaker 1: mean the spinning somehow it changes the way it's bending

292
00:15:33,520 --> 00:15:36,080
Speaker 1: space around it. Yes, even even for a perfect sphere.

293
00:15:36,200 --> 00:15:39,120
Speaker 1: Even for a perfect sphere, what it does is it

294
00:15:39,400 --> 00:15:42,880
Speaker 1: drags the space around it a little bit. It pulls

295
00:15:42,960 --> 00:15:46,240
Speaker 1: the space itself, and that's why they call it frame dragging.

296
00:15:46,640 --> 00:15:49,440
Speaker 1: It's sort of like if you had a ball and

297
00:15:49,520 --> 00:15:51,400
Speaker 1: you dipped it in honey, and then you spun the

298
00:15:51,400 --> 00:15:53,800
Speaker 1: ball a little bit, you would get the honey dragged

299
00:15:53,800 --> 00:15:56,280
Speaker 1: along with the ball, right, be a little bit of friction,

300
00:15:56,280 --> 00:15:58,640
Speaker 1: they would pull it along with it. Einstein says that

301
00:15:58,680 --> 00:16:00,520
Speaker 1: if you have a really big mass of object and

302
00:16:00,640 --> 00:16:04,520
Speaker 1: you spin it, then you drag space itself along with

303
00:16:04,640 --> 00:16:07,080
Speaker 1: the object. So they should have called it like space

304
00:16:07,160 --> 00:16:09,560
Speaker 1: dragging or something, but they call it frame dragging. You

305
00:16:09,600 --> 00:16:12,040
Speaker 1: said it not I it should have called it a

306
00:16:12,040 --> 00:16:14,240
Speaker 1: better name for sure, But what do you mean like

307
00:16:14,240 --> 00:16:16,960
Speaker 1: it drag space? How can you drag space? Long? Like?

308
00:16:17,000 --> 00:16:18,920
Speaker 1: How can you pull on space? Yeah? How can you

309
00:16:18,960 --> 00:16:21,200
Speaker 1: pull on space? Right? Like? Well, what is you in space?

310
00:16:21,280 --> 00:16:23,160
Speaker 1: We don't know? But space can do a bunch of

311
00:16:23,200 --> 00:16:26,120
Speaker 1: weird things, right. It can bend, and it can ripple,

312
00:16:26,320 --> 00:16:28,680
Speaker 1: and it can twist. So what we talk about when

313
00:16:28,680 --> 00:16:31,720
Speaker 1: we say space is curved, really what we mean there.

314
00:16:31,960 --> 00:16:34,360
Speaker 1: It's not that it's like curved like a big sheet

315
00:16:34,440 --> 00:16:37,200
Speaker 1: relatives to some other direction, but that we're changing the

316
00:16:37,320 --> 00:16:41,200
Speaker 1: relative distances between points in space, so that, for example,

317
00:16:41,360 --> 00:16:43,920
Speaker 1: the shortest path from A to B is no longer

318
00:16:44,200 --> 00:16:46,360
Speaker 1: what you would imagine to be a straight line, but

319
00:16:46,480 --> 00:16:49,040
Speaker 1: a different path because the distances between the points along

320
00:16:49,040 --> 00:16:51,360
Speaker 1: the way have been shrunk. So in the same way,

321
00:16:51,480 --> 00:16:54,680
Speaker 1: you can talk about dragging space with you as this

322
00:16:54,840 --> 00:16:58,720
Speaker 1: weird effect and additional sort of curvature of space, Like

323
00:16:58,760 --> 00:17:02,640
Speaker 1: when an object is spinning, it curves space differently around

324
00:17:02,680 --> 00:17:04,840
Speaker 1: it than if it isn't spinning. Does that due to

325
00:17:04,920 --> 00:17:07,359
Speaker 1: the fact that you know, maybe the particles or the

326
00:17:07,440 --> 00:17:09,920
Speaker 1: masses at the surface of the sphere are have some

327
00:17:10,000 --> 00:17:12,719
Speaker 1: kind of velocity, and so there's some sort of you know,

328
00:17:12,760 --> 00:17:15,520
Speaker 1: sort of lagging its effect to the things around it.

329
00:17:15,680 --> 00:17:19,200
Speaker 1: Or how would you explain what what's causing that dragging

330
00:17:19,240 --> 00:17:24,040
Speaker 1: of space. You're right that Newton assumes that gravity is instantaneous.

331
00:17:24,080 --> 00:17:27,520
Speaker 1: Like in Newton's world, if an object disappears, then it's

332
00:17:27,560 --> 00:17:31,679
Speaker 1: gravity disappears instantaneously, even for objects really far away. But

333
00:17:31,800 --> 00:17:35,400
Speaker 1: in Einstein's world, gravity takes time for information to propagate.

334
00:17:35,480 --> 00:17:38,280
Speaker 1: So if the sun disappears, we don't notice that for

335
00:17:38,359 --> 00:17:40,720
Speaker 1: eight minutes in this situation, I don't think that's the

336
00:17:40,800 --> 00:17:45,040
Speaker 1: explanation for frame dragging, because frame jagging exists even in

337
00:17:45,200 --> 00:17:47,640
Speaker 1: a object that's been spinning for like a long long

338
00:17:47,720 --> 00:17:50,959
Speaker 1: time and there's no change, no update, no like information

339
00:17:51,000 --> 00:17:53,440
Speaker 1: needs to propagate, So it can be like a steady

340
00:17:53,440 --> 00:17:56,600
Speaker 1: state situation. It's not like a transient effect. A better

341
00:17:56,680 --> 00:17:59,840
Speaker 1: way to think about it is as the gravitational version

342
00:18:00,000 --> 00:18:03,960
Speaker 1: of electromagnetic induction. If you're familiar with that concept. All right, well,

343
00:18:04,040 --> 00:18:06,439
Speaker 1: let's get a little bit deeper into this frame dragging,

344
00:18:06,560 --> 00:18:09,399
Speaker 1: and most importantly, how could we measure it and potentially

345
00:18:09,520 --> 00:18:26,080
Speaker 1: prove Einstein wrong. But first, let's take a quick break. Alright,

346
00:18:26,119 --> 00:18:30,000
Speaker 1: we're talking about proving Einstein wrong, and there's a bunch

347
00:18:30,000 --> 00:18:32,040
Speaker 1: of people out there trying to do this. Right, there's

348
00:18:32,080 --> 00:18:36,840
Speaker 1: an official government funded experiment trying to prove his theories wrong. Yeah,

349
00:18:36,840 --> 00:18:40,000
Speaker 1: there's lots of ways that we've been testing Einstein's theories. One,

350
00:18:40,040 --> 00:18:42,240
Speaker 1: of course, we're just like looking for black holes. That

351
00:18:42,280 --> 00:18:44,480
Speaker 1: was a prediction of Einstein's theory, which turned out, of

352
00:18:44,480 --> 00:18:48,440
Speaker 1: course to be correct. Another is gravitational waves. People were

353
00:18:48,480 --> 00:18:51,840
Speaker 1: looking to see if space itself would ripple when two

354
00:18:51,880 --> 00:18:54,800
Speaker 1: black holes orbit around each other and then finally gobble

355
00:18:54,840 --> 00:18:57,040
Speaker 1: each other up. And you know, we saw those that's

356
00:18:57,080 --> 00:18:59,880
Speaker 1: pretty awesome. And so all of these things are tests

357
00:19:00,000 --> 00:19:03,320
Speaker 1: of Einstein's relativity. But there's a series of folks developing

358
00:19:03,359 --> 00:19:06,240
Speaker 1: like hyper sensitive tests to look for like these like

359
00:19:06,359 --> 00:19:10,240
Speaker 1: small little deviations because we can't like organize our own

360
00:19:10,280 --> 00:19:12,880
Speaker 1: black hole experiment where were like shoot one black hole

361
00:19:12,920 --> 00:19:15,560
Speaker 1: at another, so we have to do the experiments here

362
00:19:15,600 --> 00:19:18,440
Speaker 1: on Earth. And because gravity is so weak, the effects

363
00:19:18,480 --> 00:19:21,600
Speaker 1: are really really small effects that are like really dramatic

364
00:19:21,600 --> 00:19:24,440
Speaker 1: when black holes are involved, are really not very dramatic

365
00:19:24,440 --> 00:19:27,600
Speaker 1: when ping pong balls are involved. What about black pink bubballs?

366
00:19:28,240 --> 00:19:30,600
Speaker 1: Oh my god, we didn't try that. Hold on a second,

367
00:19:31,560 --> 00:19:35,359
Speaker 1: noble price please. Alright, So one of these effects that

368
00:19:35,400 --> 00:19:38,119
Speaker 1: you're trying to test is called frame dragging, which is

369
00:19:38,280 --> 00:19:42,080
Speaker 1: how a spinning object kind of drag space around at

370
00:19:42,080 --> 00:19:44,320
Speaker 1: the edges. But there's another effect that that has to

371
00:19:44,320 --> 00:19:46,960
Speaker 1: do with gyroscopes, right, Yeah, all these effects can be

372
00:19:47,000 --> 00:19:49,680
Speaker 1: well measured by gyroscopes because what they do, in effect

373
00:19:49,800 --> 00:19:53,600
Speaker 1: is make something spin. Like the Earth has its gravity,

374
00:19:53,600 --> 00:19:56,760
Speaker 1: it's pulling on you, but if it's spinning, it's gravity

375
00:19:56,800 --> 00:19:59,320
Speaker 1: will also give you a little bit of a twist.

376
00:19:59,720 --> 00:20:02,479
Speaker 1: And so we measure these things by using gyroscopes. And

377
00:20:02,480 --> 00:20:05,200
Speaker 1: you're right, there are two different effects that can happen

378
00:20:05,240 --> 00:20:08,119
Speaker 1: to a gyroscope here. One is this frame dragging effect,

379
00:20:08,200 --> 00:20:12,119
Speaker 1: and the other is this really awesome effect, this geodetic effect.

380
00:20:12,160 --> 00:20:16,080
Speaker 1: It's called that lets you measure the curvature of space directly.

381
00:20:16,320 --> 00:20:19,040
Speaker 1: You can like exactly measure whether or not space is

382
00:20:19,119 --> 00:20:23,600
Speaker 1: curved by putting a gyroscope in orbit around a planet. Now, gyroscope, again,

383
00:20:23,640 --> 00:20:26,240
Speaker 1: it's just like a spinning mass, right exactly. You take

384
00:20:26,280 --> 00:20:28,239
Speaker 1: something and you spin it and you try to make

385
00:20:28,240 --> 00:20:31,080
Speaker 1: you really precise so it doesn't wobble, and because of

386
00:20:31,200 --> 00:20:34,160
Speaker 1: conservation of angular momentum, if nothing touches it, it should

387
00:20:34,240 --> 00:20:37,520
Speaker 1: keep spinning. Right, So there are no external forces on

388
00:20:37,560 --> 00:20:39,800
Speaker 1: a spinning object. It should keep spinning the way like

389
00:20:39,840 --> 00:20:42,200
Speaker 1: if you push something in outer space, it should keep

390
00:20:42,240 --> 00:20:45,800
Speaker 1: going forever unless something stops it. Because of angular momentum,

391
00:20:45,840 --> 00:20:47,920
Speaker 1: if you spin something like the Earth, and the Earth

392
00:20:48,000 --> 00:20:50,720
Speaker 1: is a gyroscope, it should keep spinning. And so you

393
00:20:50,720 --> 00:20:54,000
Speaker 1: can measure if there's any force on a gyroscope by

394
00:20:54,080 --> 00:20:56,959
Speaker 1: seeing if the angle of its spin changes or if

395
00:20:56,960 --> 00:20:59,919
Speaker 1: it's spin rate changes, and also like if it starts

396
00:21:00,000 --> 00:21:03,240
Speaker 1: tilting to right m exactly, they called that precession. So

397
00:21:03,280 --> 00:21:05,200
Speaker 1: if you put some force on a gyroscope, you could

398
00:21:05,200 --> 00:21:07,600
Speaker 1: slow it down, or you could change the angle of

399
00:21:07,640 --> 00:21:09,679
Speaker 1: its spin if it tilts a little bit. And so

400
00:21:09,760 --> 00:21:12,520
Speaker 1: that's what these experiments are. The one in particularly called

401
00:21:12,520 --> 00:21:16,520
Speaker 1: the gravity probe B experiment. Yeah, these are really fun experiments. Basically,

402
00:21:16,560 --> 00:21:19,560
Speaker 1: somebody said, what if we take a gyroscope and we

403
00:21:19,640 --> 00:21:22,640
Speaker 1: put it out in space and we orbit the Earth. Now,

404
00:21:22,760 --> 00:21:26,040
Speaker 1: Newton says that if the gyroscope is perfect, then the

405
00:21:26,040 --> 00:21:28,960
Speaker 1: Earth is the spirit, etcetera, etcetera. That gyroscope, once you

406
00:21:29,000 --> 00:21:32,520
Speaker 1: started spinning, will spin forever the same way, and orbiting

407
00:21:32,560 --> 00:21:34,840
Speaker 1: the Earth will have no effect on it, right, because

408
00:21:35,000 --> 00:21:37,760
Speaker 1: orbiting the Earth just pulls on it and it has gravity.

409
00:21:37,760 --> 00:21:40,200
Speaker 1: It makes it orbit, but it shouldn't change the direction

410
00:21:40,320 --> 00:21:43,359
Speaker 1: of the gyroscope. That's what Newton says, that the gyroscope

411
00:21:43,359 --> 00:21:46,800
Speaker 1: will forever point the same direction, but the geodetic effect

412
00:21:46,920 --> 00:21:49,679
Speaker 1: and the frame dragging effect, both of them will twist

413
00:21:49,720 --> 00:21:52,080
Speaker 1: this gyroscope a little bit. So they came up with

414
00:21:52,119 --> 00:21:55,800
Speaker 1: this experiment, gravity Probe B, which is basically nothing but

415
00:21:55,920 --> 00:22:00,320
Speaker 1: like a really super duper precise gyroscope in space in

416
00:22:00,480 --> 00:22:03,400
Speaker 1: orbit around the Earth like a satellite. Right, Yeah, it's

417
00:22:03,440 --> 00:22:07,240
Speaker 1: its own spacecraft. It's its own satellite, just dedicated to

418
00:22:07,320 --> 00:22:11,040
Speaker 1: actually these four spinning balls moving around the Earth. So

419
00:22:11,080 --> 00:22:14,520
Speaker 1: it's a probe because it's an experiment and it's probing gravity,

420
00:22:14,640 --> 00:22:17,320
Speaker 1: and it's B because it's the second one. Right. Gravity

421
00:22:17,320 --> 00:22:20,560
Speaker 1: Probe A was another experiment. Yeah, that's right. Gravity Probe

422
00:22:20,600 --> 00:22:24,840
Speaker 1: A was a different space based experiment to probe gravity,

423
00:22:24,880 --> 00:22:27,480
Speaker 1: but it was probing a different feature of gravity and

424
00:22:27,520 --> 00:22:29,720
Speaker 1: it used like a totally separate setup. It had like

425
00:22:29,760 --> 00:22:32,280
Speaker 1: a hydrogen maser on it, and it was measuring the

426
00:22:32,280 --> 00:22:36,560
Speaker 1: equivalence principle whether gravity is really the same as the acceleration.

427
00:22:36,640 --> 00:22:40,040
Speaker 1: You know, the whole idea of Einstein's general relativity is

428
00:22:40,160 --> 00:22:43,680
Speaker 1: that gravity, this force we feel, is just the curvature

429
00:22:43,720 --> 00:22:46,560
Speaker 1: of space. And so they're out there to measure whether

430
00:22:46,600 --> 00:22:48,720
Speaker 1: you could tell the difference between like the curvature or

431
00:22:48,720 --> 00:22:51,879
Speaker 1: space and other accelerations. And of course they found that

432
00:22:51,880 --> 00:22:55,399
Speaker 1: you couldn't. Yeah, so the gravity probe a confirm Einstein's theory,

433
00:22:55,600 --> 00:22:58,320
Speaker 1: so it didn't prove him wrong. And now we have

434
00:22:58,520 --> 00:23:01,280
Speaker 1: launched this probe B to further test then, and that

435
00:23:01,320 --> 00:23:03,880
Speaker 1: was launched a while ago, right almost fifteen years ago.

436
00:23:04,040 --> 00:23:06,840
Speaker 1: It was launched in two thousand four, and they were

437
00:23:06,880 --> 00:23:09,560
Speaker 1: sent it up there and they studied these gyroscopes for

438
00:23:09,600 --> 00:23:11,879
Speaker 1: a couple of years before they got the results. But

439
00:23:11,960 --> 00:23:14,919
Speaker 1: this is a really really hard experiment, Like, not only

440
00:23:15,160 --> 00:23:18,160
Speaker 1: is it really complicated, because like even understanding the general

441
00:23:18,160 --> 00:23:21,159
Speaker 1: relativity of what they're testing is complicated, but building a

442
00:23:21,240 --> 00:23:24,680
Speaker 1: gyroscope that's sensitive enough to see these effects, which are

443
00:23:24,720 --> 00:23:28,240
Speaker 1: really really tiny effects, is just like a huge technical

444
00:23:28,320 --> 00:23:32,159
Speaker 1: challenge because I guess these effects of gravity are not

445
00:23:32,280 --> 00:23:36,440
Speaker 1: that strong around us like here and on Earth, because

446
00:23:36,440 --> 00:23:39,760
Speaker 1: Earth Earth, it's not that massive, you know, astronomically speaking,

447
00:23:39,880 --> 00:23:41,679
Speaker 1: like if you were in a black hole. Around a

448
00:23:41,680 --> 00:23:43,720
Speaker 1: black hole, would be easier to measure these things. Yeah,

449
00:23:43,760 --> 00:23:46,720
Speaker 1: if you had stronger gravity experiments, these things would be obvious.

450
00:23:47,000 --> 00:23:49,880
Speaker 1: And also if these things were obvious in our environment,

451
00:23:50,000 --> 00:23:52,080
Speaker 1: we would have noticed them, right. Newton would have had

452
00:23:52,119 --> 00:23:54,720
Speaker 1: to incorporate them into his theories just to get like

453
00:23:54,760 --> 00:23:57,119
Speaker 1: the orbits of the planets right and stuff. And so

454
00:23:57,160 --> 00:23:59,439
Speaker 1: these are very very small effects, which is why you

455
00:23:59,440 --> 00:24:03,439
Speaker 1: need very very sensitive experiments because remember gravity is actually

456
00:24:03,480 --> 00:24:06,760
Speaker 1: a very very weak force, like it dominates the universe

457
00:24:07,080 --> 00:24:09,760
Speaker 1: in the end, controlling its structure, but it's a very

458
00:24:09,800 --> 00:24:12,880
Speaker 1: weak force compared to everything else. You know, you can

459
00:24:13,000 --> 00:24:15,960
Speaker 1: overcome gravity with a simple kitchen magnet. Every bolt of

460
00:24:16,040 --> 00:24:19,119
Speaker 1: lightning has a lot more energy than the gravitational field

461
00:24:19,119 --> 00:24:21,720
Speaker 1: of the Earth, and so it's hard to see a

462
00:24:21,840 --> 00:24:25,320
Speaker 1: very small effect gravitationally because you have to isolate it

463
00:24:25,320 --> 00:24:27,960
Speaker 1: from everything else. I guess maybe it wouldn' would have

464
00:24:28,040 --> 00:24:30,560
Speaker 1: been easier to send these pros like orbit Jupiter or

465
00:24:30,600 --> 00:24:33,800
Speaker 1: something just something heavier. It's so easy to orbit Jupiter

466
00:24:35,920 --> 00:24:37,600
Speaker 1: or the Sun, right, why don't just send it into

467
00:24:37,640 --> 00:24:42,440
Speaker 1: the Sun. Why don't they put me in charge here? No,

468
00:24:42,600 --> 00:24:45,240
Speaker 1: you're right, it's definitely would have been an advantage to

469
00:24:45,320 --> 00:24:49,000
Speaker 1: have more massive object, but it's also just harder to

470
00:24:49,119 --> 00:24:52,840
Speaker 1: control and communicate with a satellite that's much further away,

471
00:24:52,920 --> 00:24:54,760
Speaker 1: and it's just it takes years to get there, and

472
00:24:54,800 --> 00:24:57,600
Speaker 1: you need propellant and you can't repair it and all

473
00:24:57,600 --> 00:24:59,840
Speaker 1: this kind of stuff. So it's just easier to work

474
00:24:59,840 --> 00:25:02,119
Speaker 1: and your Earth orbit. All right, So let's just maybe

475
00:25:02,119 --> 00:25:04,960
Speaker 1: describe for folks how this experiment works. I mean, we

476
00:25:05,000 --> 00:25:07,919
Speaker 1: know it's got a little tiny gyroscope inside of it,

477
00:25:07,960 --> 00:25:09,280
Speaker 1: but what is how does that work? What does the

478
00:25:09,320 --> 00:25:12,439
Speaker 1: gyroscope it look like? So the gyroscope has to be

479
00:25:12,520 --> 00:25:15,360
Speaker 1: super super accurate. What you really would love to do

480
00:25:15,520 --> 00:25:18,119
Speaker 1: is just have a spinning ball in space and nothing

481
00:25:18,160 --> 00:25:21,080
Speaker 1: around it, just like totally isolated. Have a ball spinning

482
00:25:21,119 --> 00:25:23,920
Speaker 1: in space and measure as it goes around the Earth

483
00:25:24,280 --> 00:25:27,280
Speaker 1: whether it's direction of spin is changing. But of course

484
00:25:27,320 --> 00:25:28,720
Speaker 1: you can't just put a ball in space. You have

485
00:25:28,760 --> 00:25:30,399
Speaker 1: to measure it somehow, and you have to protect it

486
00:25:30,600 --> 00:25:34,040
Speaker 1: so they built this whole spacecraft around this spinning ball,

487
00:25:34,280 --> 00:25:36,119
Speaker 1: and they want this ball to be spinning, but they

488
00:25:36,119 --> 00:25:38,160
Speaker 1: don't want the spacecraft to touch it. So what they

489
00:25:38,200 --> 00:25:41,000
Speaker 1: do is they have this ping pong ball size sphere

490
00:25:41,080 --> 00:25:44,880
Speaker 1: of quartz and it has to be really super spherical

491
00:25:44,920 --> 00:25:47,600
Speaker 1: because if it's lopsided in any way at all, then

492
00:25:47,600 --> 00:25:49,960
Speaker 1: it would like develop a wobble and then you won't

493
00:25:49,960 --> 00:25:52,360
Speaker 1: be able to measure these really small effects. So they

494
00:25:52,400 --> 00:25:56,840
Speaker 1: spent like a decade perfecting how to make the roundest

495
00:25:57,040 --> 00:26:00,800
Speaker 1: object in the history of humanity. What they spent ten

496
00:26:00,920 --> 00:26:04,600
Speaker 1: years just polishing this little ball. Yeah, they'd mind this

497
00:26:04,920 --> 00:26:08,160
Speaker 1: perfect courts in Brazil, and then they have this factory

498
00:26:08,240 --> 00:26:11,280
Speaker 1: in Germany which can like polish them and melt them

499
00:26:11,320 --> 00:26:14,040
Speaker 1: and get them in exactly the right configuration. And this

500
00:26:14,119 --> 00:26:19,120
Speaker 1: thing is, I'm not joking, the most spherical object ever manufactured.

501
00:26:19,160 --> 00:26:21,640
Speaker 1: Like it has its own entry in the Guinness Book

502
00:26:21,640 --> 00:26:24,360
Speaker 1: of World Records. Wow. Well, so first of all, it's

503
00:26:24,359 --> 00:26:30,200
Speaker 1: a perfect crystal like it's one perfect lattice of courts atoms,

504
00:26:30,920 --> 00:26:34,159
Speaker 1: and then it's been polished and shaped to be this

505
00:26:34,440 --> 00:26:37,840
Speaker 1: the roundest thing ever, the roundest thing ever. It's three

506
00:26:38,040 --> 00:26:41,760
Speaker 1: ten millions of an inch from perfect spiracity. Like the

507
00:26:41,800 --> 00:26:44,520
Speaker 1: difference between you know, the radius at one point and

508
00:26:44,560 --> 00:26:49,760
Speaker 1: the radius anywhere else is this infinitesimal amount. It's amazingly smooth. Wow,

509
00:26:50,160 --> 00:26:52,560
Speaker 1: I'm imagine. Ain't some you know, old German person with

510
00:26:52,600 --> 00:26:57,119
Speaker 1: a little polishing cloth going rub for ten years? How

511
00:26:57,160 --> 00:27:01,720
Speaker 1: they did it? Yeah, that's basically that's basically it um.

512
00:27:01,760 --> 00:27:03,600
Speaker 1: And they have to make four of these things because

513
00:27:03,600 --> 00:27:06,720
Speaker 1: they wanted independent measurements. So they have four of these things,

514
00:27:06,760 --> 00:27:08,680
Speaker 1: and like to give you a sense of how smooth

515
00:27:08,720 --> 00:27:10,720
Speaker 1: this is, if you took one of these things and

516
00:27:10,760 --> 00:27:12,879
Speaker 1: you blew it up to be the size of the Earth,

517
00:27:13,119 --> 00:27:15,800
Speaker 1: then the difference between like the highest mountain and the

518
00:27:15,840 --> 00:27:18,800
Speaker 1: deepest trench would only be eight feet. So it's like

519
00:27:18,880 --> 00:27:22,080
Speaker 1: it's it's smooth at the atomic level. Yeah, there's forty

520
00:27:22,160 --> 00:27:24,840
Speaker 1: layers of atoms. Difference between the highest peak on this

521
00:27:24,920 --> 00:27:28,439
Speaker 1: thing and the deepest, like scratch on it, forty atoms.

522
00:27:28,480 --> 00:27:30,960
Speaker 1: So that German lady over there polishing it, you know,

523
00:27:31,040 --> 00:27:33,280
Speaker 1: she's doing it atom by atom, right, So then you

524
00:27:33,440 --> 00:27:35,879
Speaker 1: take these small quartz balls and then you spin them up.

525
00:27:35,960 --> 00:27:38,200
Speaker 1: Then that's your gyroscope. Do you put four of them,

526
00:27:38,200 --> 00:27:40,080
Speaker 1: and you spin them up before you launch them, or

527
00:27:40,119 --> 00:27:41,680
Speaker 1: do you spin them up and once you get the

528
00:27:41,720 --> 00:27:44,320
Speaker 1: space you spin them up down here on Earth, right,

529
00:27:44,359 --> 00:27:46,399
Speaker 1: because you got to test them. But then you also

530
00:27:46,440 --> 00:27:48,760
Speaker 1: spin them up and get them started up there in space.

531
00:27:48,960 --> 00:27:51,119
Speaker 1: But you can't just like touch them. You can't like

532
00:27:51,160 --> 00:27:53,960
Speaker 1: if you touch this thing, then you'll ruin it, right,

533
00:27:54,000 --> 00:27:56,800
Speaker 1: And so they spin them up first. They levitate them

534
00:27:57,080 --> 00:28:01,159
Speaker 1: electrostatically by you know, having this like actric field, and

535
00:28:01,200 --> 00:28:03,919
Speaker 1: then they spin them up by shooting a stream of

536
00:28:04,000 --> 00:28:07,640
Speaker 1: helium at them. They get them going four thousand revolutions

537
00:28:07,680 --> 00:28:11,000
Speaker 1: per minute, like it's got little jets of helium, you know,

538
00:28:11,200 --> 00:28:13,639
Speaker 1: hitting it kind of on the sides. Yeah, exactly provides

539
00:28:13,680 --> 00:28:16,639
Speaker 1: a little torque by shooting this stream of helium at it,

540
00:28:16,840 --> 00:28:19,960
Speaker 1: and then it evacuates the chamber, so there's no helium left.

541
00:28:20,320 --> 00:28:22,480
Speaker 1: So you have this whole spacecraft and it's sort of

542
00:28:22,560 --> 00:28:27,679
Speaker 1: surrounding this levitating ball of spinning quartz, but it's not

543
00:28:27,720 --> 00:28:30,159
Speaker 1: touching it. Oh I see, it's just floating in space.

544
00:28:30,440 --> 00:28:32,679
Speaker 1: But it doesn't drift to the size or anything. They

545
00:28:32,720 --> 00:28:35,600
Speaker 1: have these electrostatics to try to keep it from drifting

546
00:28:35,640 --> 00:28:37,720
Speaker 1: to the size because the spacecraft can drift a little

547
00:28:37,720 --> 00:28:40,280
Speaker 1: bit right, or something hits the spacecraft, then it might

548
00:28:40,320 --> 00:28:42,760
Speaker 1: bump into the ball. So they have these little like

549
00:28:42,960 --> 00:28:46,280
Speaker 1: electrostatic controls to try to like push it along with

550
00:28:46,480 --> 00:28:49,160
Speaker 1: the spacecraft. It's sort of like that game operation. You know,

551
00:28:49,360 --> 00:28:52,360
Speaker 1: you gotta like not touch the sides ever, or you

552
00:28:52,440 --> 00:28:55,080
Speaker 1: got a big buzz. Yeah, And I guess if Newton

553
00:28:55,240 --> 00:28:58,320
Speaker 1: was right and Einstein was wrong, then this little quartz

554
00:28:58,360 --> 00:29:01,360
Speaker 1: ball would keep spinning for are a really long time, like,

555
00:29:01,560 --> 00:29:04,480
Speaker 1: you know, just be spinning in space, no friction, no

556
00:29:04,600 --> 00:29:08,360
Speaker 1: air resistance, so it just spin for a really long time. Right, Yeah,

557
00:29:08,600 --> 00:29:11,400
Speaker 1: if we've done it perfectly, it would spin forever. Right.

558
00:29:11,440 --> 00:29:13,840
Speaker 1: They have not done it exactly perfectly, but they estimate

559
00:29:13,880 --> 00:29:16,000
Speaker 1: that once they spin this thing up, it shouldn't slow

560
00:29:16,080 --> 00:29:20,600
Speaker 1: down due to friction or impurities for fifteen thousand years,

561
00:29:21,000 --> 00:29:24,400
Speaker 1: which is pretty awesome feat of engineering. And then you

562
00:29:24,440 --> 00:29:27,480
Speaker 1: said they put up four lease, there's like four different

563
00:29:27,680 --> 00:29:31,680
Speaker 1: spacecraft or like one spacecraft with four little quarts balls.

564
00:29:31,920 --> 00:29:34,520
Speaker 1: It's one spacecraft with four little quartz balls in them.

565
00:29:34,760 --> 00:29:37,320
Speaker 1: And that way they get like not totally independent measurements,

566
00:29:37,400 --> 00:29:40,280
Speaker 1: because four totally separate spacecraft would have cost a lot more.

567
00:29:40,520 --> 00:29:42,440
Speaker 1: This way, if one of the balls goes wonky or

568
00:29:42,480 --> 00:29:45,080
Speaker 1: has an impurity in it, they have like three backups.

569
00:29:45,320 --> 00:29:47,160
Speaker 1: But they ended up all four of them working and

570
00:29:47,200 --> 00:29:50,160
Speaker 1: giving them measurements. And then they combine the information from

571
00:29:50,200 --> 00:29:52,640
Speaker 1: all the balls in that one spacecraft to give them

572
00:29:52,640 --> 00:29:55,600
Speaker 1: a measurement of this these procession effects. Okay, so I

573
00:29:55,600 --> 00:29:58,520
Speaker 1: guess then the question is, once you get these little

574
00:29:58,560 --> 00:30:02,560
Speaker 1: balls spinning, do they spin that for fifteen years or

575
00:30:02,760 --> 00:30:07,360
Speaker 1: do they start wobbling and wiggling due to general relativity.

576
00:30:07,840 --> 00:30:10,440
Speaker 1: So let's get into how they measured that wobble and

577
00:30:10,680 --> 00:30:14,200
Speaker 1: what does it all mean Daniel, But first let's take

578
00:30:14,200 --> 00:30:30,080
Speaker 1: another quick break. All right, we're talking about frame dragging

579
00:30:30,240 --> 00:30:33,040
Speaker 1: and the gravity probe B experiment and how it's trying

580
00:30:33,080 --> 00:30:35,920
Speaker 1: to prove Einstein wrong. All right, so it's so far

581
00:30:36,040 --> 00:30:38,800
Speaker 1: we put these four perfect quartz balls up into space,

582
00:30:38,840 --> 00:30:40,840
Speaker 1: we spun them up, and now we're trying to see

583
00:30:40,880 --> 00:30:44,760
Speaker 1: if somehow the dragging of space by a spinning Earth

584
00:30:45,040 --> 00:30:48,800
Speaker 1: will somehow make these balls wobble exactly. So there's two

585
00:30:48,800 --> 00:30:51,600
Speaker 1: effects we're looking for here. One is the geodetic effect,

586
00:30:51,640 --> 00:30:55,240
Speaker 1: which measures the curvature of space itself, because the gyroscope

587
00:30:55,280 --> 00:30:58,120
Speaker 1: going around the Earth direction it's spinning will actually twist

588
00:30:58,160 --> 00:31:00,800
Speaker 1: a little bit because the space in the vicinity is

589
00:31:00,840 --> 00:31:04,160
Speaker 1: a tiny bit curved, and that applies basically a little

590
00:31:04,200 --> 00:31:07,800
Speaker 1: force different from the actual just force of gravity pulling

591
00:31:07,800 --> 00:31:09,680
Speaker 1: it towards the center of the Earth and gives it

592
00:31:09,680 --> 00:31:12,280
Speaker 1: a little twist. Right, the force of gravity just pulls

593
00:31:12,320 --> 00:31:14,680
Speaker 1: towards the center of the Earth. This geodetic effect gives

594
00:31:14,680 --> 00:31:17,160
Speaker 1: it a little spin, and the frame dragging is a

595
00:31:17,240 --> 00:31:20,520
Speaker 1: separate effect that's pulling space along with it, and it

596
00:31:20,520 --> 00:31:23,400
Speaker 1: gives it a different kind of spin. So we're looking

597
00:31:23,400 --> 00:31:27,400
Speaker 1: for two different sort of spin changes in these gyroscopes.

598
00:31:27,720 --> 00:31:30,160
Speaker 1: One tells us about the geodetic effect and the other

599
00:31:30,200 --> 00:31:33,360
Speaker 1: one orthogonal to it, tells us about frame dragging. And

600
00:31:33,360 --> 00:31:36,280
Speaker 1: so we're trying to measure really small wobbles and these

601
00:31:36,280 --> 00:31:39,120
Speaker 1: spinning balls, and so how do we measure these things? Yeah,

602
00:31:39,160 --> 00:31:41,240
Speaker 1: that's a real challenge, right, You've got these spinning balls,

603
00:31:41,320 --> 00:31:43,400
Speaker 1: you don't ever want to touch them. So how do

604
00:31:43,440 --> 00:31:46,720
Speaker 1: you tell how a perfect sphere is spinning if you

605
00:31:46,760 --> 00:31:49,000
Speaker 1: can't even touch it? Right? So what they do is

606
00:31:49,000 --> 00:31:53,360
Speaker 1: they coat these spheres with super conducting niobium. It's this

607
00:31:53,440 --> 00:31:57,080
Speaker 1: weird element and if you get niobium really really cold,

608
00:31:57,400 --> 00:32:00,760
Speaker 1: and when it spins, then the charges nio bum generate

609
00:32:00,800 --> 00:32:04,400
Speaker 1: a magnetic field, and so you can measure the direction

610
00:32:04,440 --> 00:32:07,520
Speaker 1: of the magnetic field, which tells you exactly how this

611
00:32:07,760 --> 00:32:11,800
Speaker 1: sphere is spinning without touching the sphere itself. Oh interesting,

612
00:32:11,960 --> 00:32:13,920
Speaker 1: it's like you coated with sort of like a magnet

613
00:32:14,000 --> 00:32:16,880
Speaker 1: type of thing, and then since it's spinning, it generates

614
00:32:16,880 --> 00:32:19,720
Speaker 1: a magnetic field that you can measure if it wobbles

615
00:32:19,800 --> 00:32:22,920
Speaker 1: or not. But it's a very very slight magnetic field

616
00:32:22,920 --> 00:32:25,440
Speaker 1: because it's a very thin layer of niobium, and you

617
00:32:25,480 --> 00:32:27,200
Speaker 1: want to put a very thin, perfect layer on it

618
00:32:27,240 --> 00:32:29,480
Speaker 1: so you don't ruin, you know, the polishing job that

619
00:32:29,520 --> 00:32:32,160
Speaker 1: you're German Bubba has done. And so they have to

620
00:32:32,240 --> 00:32:36,600
Speaker 1: use these really cool magnetometers called squids that are these

621
00:32:36,640 --> 00:32:39,720
Speaker 1: fun quantum magnetomic devices that we should do a whole

622
00:32:39,720 --> 00:32:43,920
Speaker 1: other podcast about. But they're very very sensitive to very

623
00:32:43,920 --> 00:32:47,120
Speaker 1: small magnetic fields. These are the magnetic fields are like

624
00:32:47,400 --> 00:32:50,920
Speaker 1: one ten billionth of the Earth's magnetic field. So you

625
00:32:50,920 --> 00:32:53,160
Speaker 1: can't just put up any compass up there. You've got

626
00:32:53,160 --> 00:32:56,959
Speaker 1: to have a really sensitive magnetometer, but doesn't mean like

627
00:32:57,280 --> 00:33:00,520
Speaker 1: probing this magnetic field also affect the spinning ball, Like,

628
00:33:00,680 --> 00:33:04,160
Speaker 1: isn't there like a danger of like accidentally pushing it

629
00:33:04,200 --> 00:33:06,560
Speaker 1: when you're when you're trying to poke it? Absolutely, And

630
00:33:06,600 --> 00:33:08,960
Speaker 1: that's why you don't want to have like another magnet

631
00:33:09,040 --> 00:33:11,560
Speaker 1: up there. So you have this squid device which is

632
00:33:11,760 --> 00:33:15,560
Speaker 1: very very sensitive and minimally feeds back to the spinning sphere,

633
00:33:15,680 --> 00:33:18,080
Speaker 1: which you're right, You can't measure anything in this universe

634
00:33:18,120 --> 00:33:21,720
Speaker 1: without affecting it, and that includes magnets, right, Using magnetic

635
00:33:21,720 --> 00:33:23,680
Speaker 1: probe to probe magnets, it's going to have a little

636
00:33:23,720 --> 00:33:26,080
Speaker 1: bit of feedback effect, but here they think that that

637
00:33:26,160 --> 00:33:29,400
Speaker 1: feedback effect is negligible compared to the magnetic field that's

638
00:33:29,400 --> 00:33:33,680
Speaker 1: being generated. All right, So then these magnetometers are super sensitive.

639
00:33:33,760 --> 00:33:37,600
Speaker 1: If the little balls wobble by even a one tenth

640
00:33:37,600 --> 00:33:40,880
Speaker 1: of a milliarc second, which is like like a billions

641
00:33:40,920 --> 00:33:43,760
Speaker 1: of a couple of billions of a degree, right, then

642
00:33:43,800 --> 00:33:46,479
Speaker 1: they would notice, Yeah, that's right. And so it's just

643
00:33:46,680 --> 00:33:49,120
Speaker 1: super incredible that they even built this thing, and you know,

644
00:33:49,200 --> 00:33:51,840
Speaker 1: it took decades and decades. People have been thinking about

645
00:33:51,880 --> 00:33:54,960
Speaker 1: this for a long time, But they're all these engineering

646
00:33:55,040 --> 00:33:57,600
Speaker 1: problems like how do you get a gyroscope this smooth,

647
00:33:57,760 --> 00:33:59,400
Speaker 1: how do you measure it, how do you keep it

648
00:33:59,400 --> 00:34:01,600
Speaker 1: from bumping in of the spacecraft? How do you develop

649
00:34:01,600 --> 00:34:04,440
Speaker 1: a magnetomata or this sensitive? So all of these different

650
00:34:04,440 --> 00:34:07,560
Speaker 1: problems were like total roadblocks for a long time, and

651
00:34:07,560 --> 00:34:10,400
Speaker 1: then one by one they were able to overcome them

652
00:34:10,440 --> 00:34:12,920
Speaker 1: and actually put this thing together and actually build it

653
00:34:13,000 --> 00:34:15,359
Speaker 1: and send it into space and make it work. So

654
00:34:15,400 --> 00:34:18,960
Speaker 1: it's it's a real tourtive force of engineering and physics together.

655
00:34:19,160 --> 00:34:21,640
Speaker 1: So and it well went up into two thousand and four,

656
00:34:21,680 --> 00:34:23,799
Speaker 1: and they got to results in two thousand seven, so

657
00:34:23,880 --> 00:34:26,360
Speaker 1: we we know what happened. We do know what happened,

658
00:34:26,680 --> 00:34:30,000
Speaker 1: And because Einstein is still taught in school, then you'll

659
00:34:30,000 --> 00:34:32,440
Speaker 1: know the answer are already, which is that they confirmed

660
00:34:32,440 --> 00:34:35,960
Speaker 1: Einstein's prediction. So Einstein theory can be used to predict

661
00:34:36,000 --> 00:34:38,680
Speaker 1: exactly the curvature of space as you go around the

662
00:34:38,719 --> 00:34:42,080
Speaker 1: Earth and the geodetic effect this twist on the gyroscope.

663
00:34:42,160 --> 00:34:44,760
Speaker 1: It can also be used to predict how much space

664
00:34:44,840 --> 00:34:48,479
Speaker 1: is being dragged along by the Earth, and this gives

665
00:34:48,480 --> 00:34:51,600
Speaker 1: a smaller effect in a different direction and so they

666
00:34:51,600 --> 00:34:55,200
Speaker 1: saw both of these and both effects are totally consistent

667
00:34:55,480 --> 00:34:59,799
Speaker 1: with what Einstein predicted. So like, we send these things

668
00:34:59,880 --> 00:35:03,319
Speaker 1: up there, and they did exactly what Einstein predicted. Like

669
00:35:03,600 --> 00:35:06,840
Speaker 1: you can see how do these things wobble due to

670
00:35:06,840 --> 00:35:10,040
Speaker 1: the bending of space? Exactly? You can see these things

671
00:35:10,080 --> 00:35:13,239
Speaker 1: get twisted by space itself. It's hard to think about

672
00:35:13,280 --> 00:35:16,600
Speaker 1: how gravity can make something twist, right, Like, we're familiar

673
00:35:16,640 --> 00:35:19,120
Speaker 1: with gravity making something move in a circle, but actually,

674
00:35:19,200 --> 00:35:22,520
Speaker 1: like also give it a twist. It's because it's twisting

675
00:35:22,640 --> 00:35:25,840
Speaker 1: space as well, right Like, when space gets dragged along

676
00:35:25,880 --> 00:35:28,400
Speaker 1: by the Earth, it makes these weird, sort of sheer

677
00:35:28,440 --> 00:35:31,759
Speaker 1: effects in the fabric of space itself, and those come

678
00:35:31,800 --> 00:35:33,799
Speaker 1: out to be like a little twist. I think it's

679
00:35:33,800 --> 00:35:36,359
Speaker 1: also maybe helpful to try to visualize what's going on

680
00:35:36,560 --> 00:35:39,480
Speaker 1: with the geodetic effect. You're probably familiar with, Like how

681
00:35:39,520 --> 00:35:43,040
Speaker 1: you can measure the curvature of space if you take

682
00:35:43,120 --> 00:35:45,800
Speaker 1: like a triangle and you add up all the angles.

683
00:35:45,920 --> 00:35:48,320
Speaker 1: And on flat space, if you're add of all the angles,

684
00:35:48,560 --> 00:35:50,440
Speaker 1: then they all add up to a hundred eighty degrees,

685
00:35:50,600 --> 00:35:53,560
Speaker 1: but on a curve surface you might get different angles. Well,

686
00:35:53,560 --> 00:35:56,360
Speaker 1: there's another even cooler way to think about how space

687
00:35:56,440 --> 00:35:59,000
Speaker 1: is curved, and that's by thinking about a circle. You

688
00:35:59,040 --> 00:36:01,680
Speaker 1: take a circle that on a flat space and you

689
00:36:01,719 --> 00:36:05,640
Speaker 1: compare its radius to its circumference, and the relationship is

690
00:36:05,680 --> 00:36:08,280
Speaker 1: too pie right. That's famous, of course, But if space

691
00:36:08,400 --> 00:36:12,160
Speaker 1: is curved, then that no longer holds because, for example,

692
00:36:12,200 --> 00:36:15,640
Speaker 1: the radius can get longer if space is curved. So imagine,

693
00:36:15,680 --> 00:36:17,960
Speaker 1: for example, a circle around the Earth, and if the

694
00:36:18,000 --> 00:36:22,000
Speaker 1: Earth wasn't there, you could measure the radius of that circle.

695
00:36:22,120 --> 00:36:23,840
Speaker 1: You know, where the center of the circle would be

696
00:36:23,880 --> 00:36:26,440
Speaker 1: sitting nominally at the center of the Earth, and that

697
00:36:26,520 --> 00:36:29,080
Speaker 1: would be the radius of the Earth, and the circumstance

698
00:36:29,160 --> 00:36:31,359
Speaker 1: of the circle would be the circumference of the Earth.

699
00:36:31,640 --> 00:36:34,359
Speaker 1: But because space is bent, and that path actually gets

700
00:36:34,400 --> 00:36:37,640
Speaker 1: a little bit longer, right, because like imagine, for example,

701
00:36:37,680 --> 00:36:39,560
Speaker 1: you have like a circle with a bubble in it.

702
00:36:39,920 --> 00:36:42,600
Speaker 1: If you move along the bubble, then you're going to

703
00:36:42,680 --> 00:36:46,040
Speaker 1: measure larger radius than if you're just moving exactly towards

704
00:36:46,120 --> 00:36:48,200
Speaker 1: the center. Right. It's like trying to measure the equator

705
00:36:48,239 --> 00:36:50,080
Speaker 1: from the north pole. You'd have to sort of go

706
00:36:50,200 --> 00:36:53,440
Speaker 1: around the coverature of the Earth. Yeah, and so what

707
00:36:53,440 --> 00:36:56,000
Speaker 1: we're doing here is we're sort of measuring, you know,

708
00:36:56,239 --> 00:36:59,200
Speaker 1: pie in some sense, we're measuring whether moving around the

709
00:36:59,200 --> 00:37:01,840
Speaker 1: Earth sort of lines up with the radius of the Earth.

710
00:37:02,160 --> 00:37:04,800
Speaker 1: So that's one thing that the geodetic effect is measuring,

711
00:37:05,080 --> 00:37:08,759
Speaker 1: is the local curvature. And if there was no curvature

712
00:37:09,000 --> 00:37:11,520
Speaker 1: in that space, then moving around the Earth a gyroscope

713
00:37:11,560 --> 00:37:14,080
Speaker 1: wouldn't process at all. But because there is that little

714
00:37:14,120 --> 00:37:16,960
Speaker 1: bit of curvature, then things don't quite line up. You know,

715
00:37:16,960 --> 00:37:19,440
Speaker 1: the radius and the circumference don't have the right relationship.

716
00:37:19,560 --> 00:37:23,160
Speaker 1: So you get this very small effect that's the geodetic effect. Cool,

717
00:37:23,239 --> 00:37:26,399
Speaker 1: and so the gravity probe be confirmed is like these

718
00:37:26,400 --> 00:37:30,560
Speaker 1: are super tiny, subtle effects, but this instrument actually wasn't

719
00:37:30,560 --> 00:37:32,600
Speaker 1: able to measure this bending of space. I feel like

720
00:37:32,719 --> 00:37:34,920
Speaker 1: it brings it all to the really home, you know,

721
00:37:34,960 --> 00:37:37,319
Speaker 1: it's not just something that's happening around the edges of

722
00:37:37,400 --> 00:37:39,960
Speaker 1: black holes. It's like, you can measure the bending of

723
00:37:40,000 --> 00:37:43,399
Speaker 1: space around Earth like a few a few miles from

724
00:37:43,400 --> 00:37:45,600
Speaker 1: where you are right now. Yeah, if you have thirty years,

725
00:37:45,680 --> 00:37:49,480
Speaker 1: eight hundred million dollars, you two can measure the curvature days.

726
00:37:51,360 --> 00:37:53,520
Speaker 1: Bezos could do this a couple of times a day.

727
00:37:54,640 --> 00:37:56,440
Speaker 1: You can do it before lunch. But you're right, it's

728
00:37:56,440 --> 00:37:59,240
Speaker 1: a real tutor force. It's amazing. It's a big effect

729
00:37:59,280 --> 00:38:02,400
Speaker 1: at black Hole, and it's a really almost negligible effect here. Like,

730
00:38:02,560 --> 00:38:06,560
Speaker 1: nobody needs to include these calculations even in their satellite

731
00:38:06,800 --> 00:38:09,719
Speaker 1: navigation problems. You know, nobody needs to worry about these

732
00:38:09,760 --> 00:38:13,279
Speaker 1: things now. But they're included in the GPS calculations, right,

733
00:38:13,360 --> 00:38:16,360
Speaker 1: Like the GPS and your phone takes into account the

734
00:38:16,360 --> 00:38:19,920
Speaker 1: curricture of space or the effects of relativity. They the

735
00:38:19,920 --> 00:38:22,280
Speaker 1: GPS on your phone definitely takes into account the effects

736
00:38:22,280 --> 00:38:25,680
Speaker 1: of relativity, but that's mostly the time dilation, the fact

737
00:38:25,680 --> 00:38:28,200
Speaker 1: that down here on Earth were closer to the Earth's

738
00:38:28,200 --> 00:38:31,200
Speaker 1: gravitational well, and so time moves a little bit slower.

739
00:38:31,280 --> 00:38:34,040
Speaker 1: So relativity is all sorts of effects. These effects, the

740
00:38:34,080 --> 00:38:36,800
Speaker 1: geodetic effect and the frame dragging effect, don't need to

741
00:38:36,800 --> 00:38:39,560
Speaker 1: be included in GPS. If they did, then we could

742
00:38:39,560 --> 00:38:42,520
Speaker 1: just use GPS directly to measure them. But you need

743
00:38:42,560 --> 00:38:46,319
Speaker 1: like a special super isolated, complicated experiment just to prove

744
00:38:46,360 --> 00:38:49,320
Speaker 1: that these effects even exist, so we can safely ignore

745
00:38:49,360 --> 00:38:52,799
Speaker 1: them in GPS calculations. But you definitely right, GPS uses

746
00:38:52,880 --> 00:38:55,560
Speaker 1: other effects of relativity right, Yeah, I guess. I mean,

747
00:38:55,640 --> 00:38:59,200
Speaker 1: you know, like the basically the bending of spacetime that

748
00:38:59,480 --> 00:39:02,200
Speaker 1: Einstein figure it out. It is, it's in our everyday lives.

749
00:39:02,360 --> 00:39:04,520
Speaker 1: It is, it affects our lives. It determines whether or

750
00:39:04,560 --> 00:39:06,480
Speaker 1: not we get where we're going. All right, So then

751
00:39:06,560 --> 00:39:09,719
Speaker 1: Einstein was right. No surprise there, I guess. I guess

752
00:39:09,719 --> 00:39:12,560
Speaker 1: where people expecting him to be wrong? They were they

753
00:39:12,600 --> 00:39:15,319
Speaker 1: hoping he was wrong? Or are they happy to confirm it.

754
00:39:15,600 --> 00:39:18,360
Speaker 1: I think that the guys who built this satellite wanted

755
00:39:18,440 --> 00:39:20,279
Speaker 1: him to be right because they were set out to

756
00:39:20,320 --> 00:39:23,120
Speaker 1: measure it, and you know, to prove that this effect

757
00:39:23,239 --> 00:39:25,960
Speaker 1: is real. So I suspect they wanted him to be right.

758
00:39:26,000 --> 00:39:29,319
Speaker 1: But I was rooting against Einstein. I definitely wanted him

759
00:39:29,320 --> 00:39:32,440
Speaker 1: to be wrong. Oh man, I got nothing against the guy.

760
00:39:32,440 --> 00:39:34,120
Speaker 1: I mean, I don't know him at all, But it

761
00:39:34,160 --> 00:39:36,799
Speaker 1: would be super cool to measure a different effect, right,

762
00:39:36,840 --> 00:39:39,360
Speaker 1: to go up there and have these super sensitive devices

763
00:39:39,400 --> 00:39:42,120
Speaker 1: that can measure the curvature space and you see something weird,

764
00:39:42,239 --> 00:39:46,080
Speaker 1: something non Einsteinian, something that gives us a clue about

765
00:39:46,160 --> 00:39:49,080
Speaker 1: how the future theory of gravity needs to look. So

766
00:39:49,239 --> 00:39:51,920
Speaker 1: you always want everyone to be wrong. Daniel that seems

767
00:39:51,920 --> 00:39:56,080
Speaker 1: like a difficult perspective to have as a collaborator, But

768
00:39:56,160 --> 00:39:59,320
Speaker 1: together we all want to discover flaws in our theory

769
00:39:59,360 --> 00:40:02,600
Speaker 1: because those are the potential learning moments. Right when our

770
00:40:02,680 --> 00:40:05,440
Speaker 1: theory predicts something that doesn't happen, or fails to predict

771
00:40:05,480 --> 00:40:08,120
Speaker 1: something that does happen, that's a time when we can

772
00:40:08,160 --> 00:40:10,720
Speaker 1: pull on that threat and unravel the mystery and reveal

773
00:40:10,840 --> 00:40:14,800
Speaker 1: something deep about the universe. So it's cool that Einstein

774
00:40:14,880 --> 00:40:17,560
Speaker 1: was right. It's awesome. It's need kudos to these folks

775
00:40:17,560 --> 00:40:19,520
Speaker 1: who built this experiment, But I think it would be

776
00:40:19,680 --> 00:40:22,359
Speaker 1: much more cool if they saw something weird and new

777
00:40:22,680 --> 00:40:24,640
Speaker 1: that gives us a clue about how to build a

778
00:40:24,680 --> 00:40:27,040
Speaker 1: theory of quantum gravity, right, or at least maybe like

779
00:40:27,080 --> 00:40:31,319
Speaker 1: a clue as to how to put together you know,

780
00:40:31,880 --> 00:40:35,719
Speaker 1: general relativity and quantum mechanics, right, because that's still the

781
00:40:35,760 --> 00:40:39,160
Speaker 1: big mystery, and probably confirming this further, it just makes

782
00:40:39,200 --> 00:40:42,359
Speaker 1: it harder to figure out what's going on. Yeah, we're

783
00:40:42,440 --> 00:40:45,720
Speaker 1: sort of stuck, right. I deeply believe that Einstein's theory

784
00:40:45,800 --> 00:40:49,080
Speaker 1: can't be a real description of nature, But until it fails,

785
00:40:49,360 --> 00:40:51,160
Speaker 1: we don't really know what to replace it with. We

786
00:40:51,160 --> 00:40:54,280
Speaker 1: don't really have a better idea, and people are working

787
00:40:54,280 --> 00:40:57,160
Speaker 1: on all sorts of stuff string theory and loop quantum gravity,

788
00:40:57,200 --> 00:40:59,680
Speaker 1: and we have podcast episodes on that you can check out.

789
00:41:00,040 --> 00:41:02,040
Speaker 1: But so far, none of those really work, none of

790
00:41:02,040 --> 00:41:06,480
Speaker 1: those succeed in unifying quantum mechanics and gravity, and so

791
00:41:06,560 --> 00:41:08,680
Speaker 1: we're still at a loss. And you know, we could

792
00:41:08,760 --> 00:41:11,560
Speaker 1: continue to work theoretically, just like waiting to have a

793
00:41:11,600 --> 00:41:14,720
Speaker 1: good idea, but I'm hoping to get a clue experimentally.

794
00:41:14,880 --> 00:41:17,200
Speaker 1: I'm hoping to break one of these things to see

795
00:41:17,239 --> 00:41:20,440
Speaker 1: some new weird effect that requires us, that inspires us

796
00:41:20,600 --> 00:41:22,719
Speaker 1: to come up with a new theory. Right, and you're

797
00:41:22,719 --> 00:41:24,879
Speaker 1: a quantum physicist, so I'm going to assume that you're

798
00:41:24,920 --> 00:41:28,040
Speaker 1: just gonna buy default route for the other team to

799
00:41:28,080 --> 00:41:31,200
Speaker 1: be wrong. That's what experimentalists try to do, right. We're

800
00:41:31,200 --> 00:41:33,560
Speaker 1: not out to just confirm people's theories is correct. We're

801
00:41:33,600 --> 00:41:36,800
Speaker 1: rather to discover new stuff, to see weird things in

802
00:41:36,840 --> 00:41:39,759
Speaker 1: the universe that give you clues just about how things

803
00:41:39,760 --> 00:41:42,760
Speaker 1: really work. Well, in this case, they confirm Einstein's theories.

804
00:41:42,840 --> 00:41:44,799
Speaker 1: And it's pretty cool that you can go out there

805
00:41:44,960 --> 00:41:48,160
Speaker 1: and see the bending of space or at least measure

806
00:41:48,200 --> 00:41:51,719
Speaker 1: it with really accurate evolves made out of course, but

807
00:41:51,960 --> 00:41:53,960
Speaker 1: you know, it's the thing you can measure and test

808
00:41:54,000 --> 00:41:56,879
Speaker 1: and probe and get data on and know that it's

809
00:41:56,920 --> 00:41:59,920
Speaker 1: actually happening in this universe. Weird stuff like that predicted

810
00:42:00,000 --> 00:42:03,760
Speaker 1: by this beautiful mathematical theory is real. Like space really

811
00:42:03,840 --> 00:42:06,200
Speaker 1: is getting twisted around the Earth. This is not just

812
00:42:06,320 --> 00:42:09,440
Speaker 1: a calculation. This is our universe. All right. Well, we

813
00:42:09,480 --> 00:42:12,600
Speaker 1: hope you enjoyed that, and please remember to turn your

814
00:42:12,640 --> 00:42:15,400
Speaker 1: chicken or turn off the stove as you listen to

815
00:42:15,520 --> 00:42:18,560
Speaker 1: this podcast. We don't want to cause any accidents out there,

816
00:42:18,920 --> 00:42:21,399
Speaker 1: at least not here on Earth, maybe in space. It's

817
00:42:21,400 --> 00:42:24,200
Speaker 1: all right, and pay attention to your kids. Well, thanks

818
00:42:24,239 --> 00:42:34,920
Speaker 1: for joining us, see you next time. Thanks for listening,

819
00:42:35,000 --> 00:42:37,680
Speaker 1: and remember that Daniel and Jorge Explain the Universe is

820
00:42:37,760 --> 00:42:41,239
Speaker 1: a production of I Heart Radio. Or more podcast from

821
00:42:41,239 --> 00:42:45,040
Speaker 1: my Heart Radio. Visit the I Heart Radio, Apple Apple Podcasts,

822
00:42:45,120 --> 00:42:47,480
Speaker 1: or wherever you listen to your favorite shows.