Hawking's Triumph, Balloon Telescopes, and a Tilted Exoplanet

WEBVTT

0
00:00:00.320 --> 00:00:02.960
Avery: Hello, and ah, welcome to Astronomy Daily,

1
00:00:03.040 --> 00:00:05.640
the podcast that brings the cosmos down to

2
00:00:05.640 --> 00:00:08.600
Earth. I'm Avery, and as always, I'm

3
00:00:08.600 --> 00:00:10.400
here with the brilliant Anna.

4
00:00:10.560 --> 00:00:13.320
Anna: Hello, Avery, and hello to all our

5
00:00:13.320 --> 00:00:16.080
listeners. We have a fascinating lineup today

6
00:00:16.240 --> 00:00:18.880
covering everything from cosmic giants

7
00:00:18.880 --> 00:00:21.280
to microscopic survivors.

8
00:00:21.680 --> 00:00:24.280
Avery: That's right. We'll be talking about a major

9
00:00:24.280 --> 00:00:26.720
confirmation of a Stephen Hawking theory.

10
00:00:27.040 --> 00:00:29.600
Moths that survived the vacuum of space.

11
00:00:29.920 --> 00:00:32.660
A telescope on a balloon. A planet that's

12
00:00:32.660 --> 00:00:35.460
orbiting completely off kilter. And we'll end

13
00:00:35.460 --> 00:00:37.740
by tackling one of the biggest questions out

14
00:00:37.740 --> 00:00:40.380
there. Is the universe infinite?

15
00:00:40.540 --> 00:00:42.300
Anna: It's a packed episode.

16
00:00:42.620 --> 00:00:43.980
Shall we start with the giants?

17
00:00:44.300 --> 00:00:47.020
Avery: Let's do it. Our first story is a big

18
00:00:47.020 --> 00:00:49.660
one. Two of the greatest minds in physics,

19
00:00:49.660 --> 00:00:52.380
Stephen Hawking and Albert Einstein,

20
00:00:52.460 --> 00:00:54.620
both had some of their most fundamental

21
00:00:54.620 --> 00:00:57.540
predictions confirmed by a single cosmic

22
00:00:57.540 --> 00:00:57.820
event.

23
00:00:58.300 --> 00:01:00.660
Anna: This involves the collision of two black

24
00:01:00.660 --> 00:01:03.100
holes. Using gravitational wave

25
00:01:03.100 --> 00:01:05.860
observatories, scientists got their clearest

26
00:01:05.860 --> 00:01:07.980
observation yet of such a merger.

27
00:01:08.300 --> 00:01:11.060
Avery: And the first big confirmation relates to

28
00:01:11.060 --> 00:01:13.860
Hawking's area theorem. Um, he predicted that

29
00:01:13.860 --> 00:01:16.780
the surface area of a black hole, its event

30
00:01:16.780 --> 00:01:19.620
horizon can never, ever shrink. It

31
00:01:19.620 --> 00:01:21.660
can only stay the same or grow.

32
00:01:22.140 --> 00:01:25.020
Anna: Right. It's a law of black hole mechanics.

33
00:01:25.260 --> 00:01:27.990
And in this merger, they measured the surface

34
00:01:27.990 --> 00:01:30.830
area of the two original black holes and

35
00:01:30.830 --> 00:01:33.150
compared it to the new, larger one that

36
00:01:33.150 --> 00:01:33.670
formed.

37
00:01:33.990 --> 00:01:34.390
Avery: And?

38
00:01:34.870 --> 00:01:37.470
Anna: And the new surface area was indeed

39
00:01:37.470 --> 00:01:40.310
greater than the sum of the two initial ones.

40
00:01:40.550 --> 00:01:41.830
Hawking was right.

41
00:01:42.150 --> 00:01:44.670
Avery: It's just incredible to see a theoretical

42
00:01:44.670 --> 00:01:47.670
prediction made decades ago proven so

43
00:01:47.670 --> 00:01:50.430
precisely. But that wasn't all they saw, was

44
00:01:50.430 --> 00:01:50.710
it?

45
00:01:50.950 --> 00:01:53.710
Anna: No, it wasn't. The signal was so

46
00:01:53.710 --> 00:01:56.150
clear that they could observe the ring down

47
00:01:56.150 --> 00:01:58.590
of the new black hole. Think of it like

48
00:01:58.590 --> 00:01:59.590
striking a bell.

49
00:01:59.810 --> 00:02:01.190
Avery: Mhm. The ringing.

50
00:02:01.270 --> 00:02:04.110
Anna: Exactly. The new black hole wobbled

51
00:02:04.110 --> 00:02:07.070
and settled into its final shape, sending out

52
00:02:07.070 --> 00:02:09.510
gravitational waves that faded over time,

53
00:02:09.830 --> 00:02:12.430
just like the sound of a bell. The specific

54
00:02:12.430 --> 00:02:14.710
frequencies and decay patterns of that ring

55
00:02:14.710 --> 00:02:17.590
down matched the predictions of Einstein's

56
00:02:17.590 --> 00:02:19.430
general theory of relativity perhaps

57
00:02:19.580 --> 00:02:20.140
perfectly.

58
00:02:20.300 --> 00:02:22.700
Avery: So in one event, we get a check mark for

59
00:02:22.700 --> 00:02:25.420
Hawking and a check mark for Einstein.

60
00:02:25.660 --> 00:02:28.340
And this new object they observed is called a

61
00:02:28.340 --> 00:02:29.900
Kerr black hole, right?

62
00:02:30.060 --> 00:02:32.900
Anna: That's correct. A Kerr black hole is one that

63
00:02:32.900 --> 00:02:35.699
is rotating. Since the two smaller black

64
00:02:35.699 --> 00:02:38.060
holes were spiraling around each other, the

65
00:02:38.060 --> 00:02:40.860
resulting merged black hole inherited that

66
00:02:40.860 --> 00:02:43.500
spin. It's the type of black hole we expect

67
00:02:43.500 --> 00:02:45.020
to be common in the universe.

68
00:02:45.570 --> 00:02:48.170
Avery: Wow. What a powerful confirmation of our

69
00:02:48.170 --> 00:02:50.530
understanding of gravity and the universe.

70
00:02:50.850 --> 00:02:53.610
From the colossal to the well to the very,

71
00:02:53.610 --> 00:02:54.370
very small.

72
00:02:54.690 --> 00:02:57.650
Our next story is almost the polar opposite.

73
00:02:57.890 --> 00:03:00.770
Anna: It really is. This story comes from

74
00:03:00.770 --> 00:03:03.530
the International Space Station, but it's not

75
00:03:03.530 --> 00:03:06.290
about the astronauts inside. It's about

76
00:03:06.290 --> 00:03:08.210
something that was living on the outside.

77
00:03:08.690 --> 00:03:11.330
Avery: On the outside? Fully exposed to space.

78
00:03:12.010 --> 00:03:15.010
Anna: Fully exposed. Scientists placed moss

79
00:03:15.010 --> 00:03:17.850
spores in a container on an external platform

80
00:03:17.850 --> 00:03:20.570
of the iss. For nine months, these

81
00:03:20.570 --> 00:03:22.890
spores endured the vacuum of space,

82
00:03:23.290 --> 00:03:26.090
extreme temperature swings, and the full

83
00:03:26.090 --> 00:03:27.850
force of cosmic radiation.

84
00:03:28.170 --> 00:03:29.970
Avery: That sounds like a recipe for total

85
00:03:29.970 --> 00:03:32.130
destruction. I can't imagine anything

86
00:03:32.130 --> 00:03:32.970
surviving that.

87
00:03:33.210 --> 00:03:36.130
Anna: That's what makes this so astonishing. When

88
00:03:36.130 --> 00:03:38.370
they brought the spores back to Earth, a high

89
00:03:38.370 --> 00:03:40.490
percentage of them were still able to

90
00:03:40.490 --> 00:03:41.610
germinate and grow.

91
00:03:42.130 --> 00:03:44.890
Avery: No way. They just started growing

92
00:03:44.890 --> 00:03:46.090
again after nine.

93
00:03:46.090 --> 00:03:49.090
Anna: Months in raw space as if nothing had

94
00:03:49.090 --> 00:03:51.370
happened. It speaks to the incredible

95
00:03:51.370 --> 00:03:54.330
resilience of life. Organisms like

96
00:03:54.330 --> 00:03:57.210
this, known as extremophiles, really

97
00:03:57.210 --> 00:03:59.290
push the boundaries of what we thought was

98
00:03:59.290 --> 00:03:59.650
possible.

99
00:04:00.050 --> 00:04:02.450
Avery: This has huge implications for theories like

100
00:04:02.450 --> 00:04:05.050
panspermia, doesn't it? The idea that life

101
00:04:05.050 --> 00:04:07.690
could travel between planets on asteroids or

102
00:04:07.690 --> 00:04:08.130
comets.

103
00:04:08.770 --> 00:04:11.770
Anna: It certainly makes it seem more plausible. If

104
00:04:11.770 --> 00:04:14.450
simple spores can survive the harshness of

105
00:04:14.450 --> 00:04:17.450
space for extended periods, it suggests

106
00:04:17.450 --> 00:04:19.530
that the building blocks of life might be

107
00:04:19.530 --> 00:04:21.770
tougher and more widespread than we ever

108
00:04:21.770 --> 00:04:22.290
imagined.

109
00:04:23.010 --> 00:04:25.730
Avery: From survivors in space to a new way of

110
00:04:25.730 --> 00:04:26.530
seeing in space.

111
00:04:27.010 --> 00:04:29.490
Our next story involves a very unusual

112
00:04:29.490 --> 00:04:32.210
observatory. We're not talking about a

113
00:04:32.210 --> 00:04:35.020
mountaintop or a satellite, but a telescope

114
00:04:35.100 --> 00:04:36.940
dangling from a giant balloon.

115
00:04:37.340 --> 00:04:40.260
Anna: This is the Excalibur mission. And while a

116
00:04:40.260 --> 00:04:43.180
balloon might sound low tech, it's actually

117
00:04:43.420 --> 00:04:46.060
an incredibly clever way to do astronomy.

118
00:04:46.220 --> 00:04:48.380
Avery: It carries a telescope up to about

119
00:04:48.460 --> 00:04:51.140
130,000ft, which is above

120
00:04:51.140 --> 00:04:54.100
99% of Earth's atmosphere. This

121
00:04:54.100 --> 00:04:56.580
gives it a much clearer view, especially for

122
00:04:56.580 --> 00:04:59.220
the kind of light it's designed to see. High

123
00:04:59.220 --> 00:05:00.380
energy X rays.

124
00:05:00.820 --> 00:05:03.420
Anna: Mm X rays that are blocked by our

125
00:05:03.420 --> 00:05:06.340
atmosphere. And Excalibur isn't just taking

126
00:05:06.340 --> 00:05:09.260
pictures. Its key function is to measure

127
00:05:09.260 --> 00:05:11.540
the polarization of these X rays.

128
00:05:11.700 --> 00:05:13.900
Avery: Can you break that down for us? What does

129
00:05:13.900 --> 00:05:16.380
measuring polarization actually tell?

130
00:05:16.380 --> 00:05:18.980
Anna: You think of light as a wave.

131
00:05:19.300 --> 00:05:22.180
Usually those waves are oriented randomly.

132
00:05:22.580 --> 00:05:25.340
Polarization is like filtering the light, so

133
00:05:25.340 --> 00:05:27.940
you only see waves oriented in a specific

134
00:05:27.940 --> 00:05:30.880
direction. For astronomers, the. The way X

135
00:05:30.880 --> 00:05:33.360
rays are polarized tells them about the

136
00:05:33.360 --> 00:05:36.160
powerful and complex magnetic fields

137
00:05:36.320 --> 00:05:37.360
near their source.

138
00:05:38.160 --> 00:05:40.560
Avery: So it's a way to map out invisible

139
00:05:40.560 --> 00:05:43.160
magnetic structures. And they pointed this

140
00:05:43.160 --> 00:05:45.480
thing at some pretty famous cosmic objects,

141
00:05:45.480 --> 00:05:45.760
right?

142
00:05:46.320 --> 00:05:49.040
Anna: They did. The mission focused on two

143
00:05:49.040 --> 00:05:52.040
main the Crab Nebula, which is the

144
00:05:52.040 --> 00:05:54.880
remnant of a supernova, and Cygnus

145
00:05:54.880 --> 00:05:57.840
X1, a famous system containing a

146
00:05:57.840 --> 00:06:00.320
black hole that's feeding off a companion

147
00:06:00.320 --> 00:06:00.680
star.

148
00:06:01.400 --> 00:06:04.040
Avery: And by measuring the X ray polarization.

149
00:06:04.680 --> 00:06:06.880
They are getting new insights into the

150
00:06:06.880 --> 00:06:09.360
physics of the neutron star powering the Crab

151
00:06:09.360 --> 00:06:12.319
Nebula and the geometry of the material

152
00:06:12.319 --> 00:06:15.000
swirling into the black hole in Cygnus X1.

153
00:06:15.240 --> 00:06:17.000
It's a whole new layer of information.

154
00:06:17.800 --> 00:06:20.200
Anna: It really is. Balloon based

155
00:06:20.200 --> 00:06:23.120
astronomy provides a fantastic, cost

156
00:06:23.120 --> 00:06:25.760
effective way to get above the atmosphere and

157
00:06:25.760 --> 00:06:27.080
test new technologies.

158
00:06:27.860 --> 00:06:30.500
Okay, from new views to new mysteries,

159
00:06:30.740 --> 00:06:33.620
our next story presents a real puzzle.

160
00:06:33.700 --> 00:06:35.780
Avery: Yeah, this one is a head scratcher.

161
00:06:36.020 --> 00:06:38.340
Astronomers have found an exoplanet system

162
00:06:38.580 --> 00:06:41.140
named TOI 3884

163
00:06:41.460 --> 00:06:43.300
where things just don't add up.

164
00:06:43.619 --> 00:06:45.860
Anna: The planet itself is a super

165
00:06:45.940 --> 00:06:48.860
neptune, larger than Neptune, but smaller

166
00:06:48.860 --> 00:06:51.500
than Saturn. It orbits its star quite

167
00:06:51.500 --> 00:06:54.470
closely. But that's not the strange part. The

168
00:06:54.470 --> 00:06:56.910
strangeness lies in its orbit.

169
00:06:57.550 --> 00:07:00.510
Avery: It's wildly tilted. Most planets

170
00:07:00.510 --> 00:07:03.230
in a solar system form in a flat disk,

171
00:07:03.390 --> 00:07:05.710
so they tend to orbit in the same plane

172
00:07:05.870 --> 00:07:08.870
aligned with the star's equator. This

173
00:07:08.870 --> 00:07:11.070
one is misaligned by about

174
00:07:11.230 --> 00:07:14.070
62 degrees. It's orbiting on

175
00:07:14.070 --> 00:07:16.030
a crazy diagonal path.

176
00:07:16.670 --> 00:07:19.430
Anna: Right. A 62 degree tilt is

177
00:07:19.430 --> 00:07:22.190
extreme. Usually to get an orbit that

178
00:07:22.190 --> 00:07:24.990
tilted, you need a powerful gravitational

179
00:07:24.990 --> 00:07:27.410
nudge from m, another massive object in the

180
00:07:27.410 --> 00:07:30.010
system. Like a giant planet farther out

181
00:07:30.250 --> 00:07:31.690
or a, uh, companion star.

182
00:07:32.330 --> 00:07:35.050
Avery: And the mystery is there isn't one.

183
00:07:35.370 --> 00:07:37.530
Scientists have looked and they can't find

184
00:07:37.610 --> 00:07:40.370
anything massive enough nearby to explain

185
00:07:40.370 --> 00:07:43.210
how this planet got knocked so far off

186
00:07:43.210 --> 00:07:43.690
kilter.

187
00:07:44.250 --> 00:07:47.210
Anna: Precisely. The usual suspects are all

188
00:07:47.210 --> 00:07:49.290
missing. It leaves them with some

189
00:07:49.290 --> 00:07:51.930
unconventional theories. Perhaps the

190
00:07:51.930 --> 00:07:54.730
stars protoplanetary disk was tilted

191
00:07:54.730 --> 00:07:57.250
from the very beginning by a passing star

192
00:07:57.250 --> 00:07:59.770
early in its history. Or maybe there was

193
00:07:59.770 --> 00:08:01.970
another planet that knocked this one aside

194
00:08:02.050 --> 00:08:04.210
and then got ejected from the system

195
00:08:04.450 --> 00:08:05.170
entirely.

196
00:08:05.730 --> 00:08:07.410
Avery: A, uh, cosmic hit and run.

197
00:08:07.890 --> 00:08:08.610
Anna: Exactly.

198
00:08:09.170 --> 00:08:11.600
Avery: And that theory of an ejected planet, A, uh,

199
00:08:11.650 --> 00:08:14.290
cosmic hit and run. Why is that

200
00:08:14.370 --> 00:08:15.890
so difficult to prove?

201
00:08:16.530 --> 00:08:19.290
Anna: Because the getaway car is long gone

202
00:08:19.290 --> 00:08:21.860
and completely invisible. A planet

203
00:08:21.860 --> 00:08:24.420
ejected from its solar system would become a

204
00:08:24.420 --> 00:08:27.260
rogue planet, drifting cold and dark through

205
00:08:27.260 --> 00:08:29.900
interstellar space. There's no star to light

206
00:08:29.900 --> 00:08:32.780
it up. So finding it, let alone tracing

207
00:08:32.780 --> 00:08:35.340
it back to its home system, is practically

208
00:08:35.340 --> 00:08:36.900
impossible with our current technology.

209
00:08:37.940 --> 00:08:40.220
Avery: So scientists have a pretty big mystery.

210
00:08:40.220 --> 00:08:42.340
Anna: On their hands, essentially.

211
00:08:42.980 --> 00:08:45.620
For now, it's an open case file.

212
00:08:46.020 --> 00:08:49.020
It's a reminder that planet formation is a

213
00:08:49.020 --> 00:08:51.940
chaotic and complex process. And

214
00:08:51.940 --> 00:08:54.480
our own solar system systems neat alignment

215
00:08:54.880 --> 00:08:56.960
might be less common than we think.

216
00:08:57.840 --> 00:08:59.760
Avery: Speaking of things being less common than we

217
00:08:59.760 --> 00:09:02.440
think, our final story tackles maybe the

218
00:09:02.440 --> 00:09:05.360
biggest astronomical question of Is

219
00:09:05.360 --> 00:09:06.800
the universe infinite?

220
00:09:07.520 --> 00:09:09.600
Anna: It's a question that feels almost

221
00:09:09.760 --> 00:09:12.640
philosophical, but scientists are trying

222
00:09:12.640 --> 00:09:14.880
to answer it with actual measurements.

223
00:09:15.520 --> 00:09:18.400
The Key lies in determining the overall

224
00:09:18.400 --> 00:09:21.120
shape or geometry of the universe.

225
00:09:22.000 --> 00:09:24.080
Avery: And their best tool for that is the cosmic

226
00:09:24.080 --> 00:09:26.160
microwave background, or cmb.

227
00:09:26.800 --> 00:09:29.040
That's the leftover heat from the Big Bang,

228
00:09:29.040 --> 00:09:30.720
which fills all of space.

229
00:09:32.080 --> 00:09:34.600
Anna: Correct. By studying the tiny

230
00:09:34.600 --> 00:09:36.880
temperature fluctuations in the cmb,

231
00:09:37.439 --> 00:09:40.000
cosmologists can measure the universe's

232
00:09:40.000 --> 00:09:42.960
geometry. There are three basic

233
00:09:42.960 --> 00:09:45.840
possibilities. It could be closed,

234
00:09:46.000 --> 00:09:48.690
like the surface of a sphere, open

235
00:09:49.090 --> 00:09:52.050
like the surface of a saddle, or flat,

236
00:09:52.130 --> 00:09:53.410
like a sheet of paper.

237
00:09:54.210 --> 00:09:56.610
Avery: And so far, every measurement we've made

238
00:09:56.610 --> 00:09:58.130
points to one answer.

239
00:09:58.850 --> 00:10:01.810
Anna: Flat to within a very small

240
00:10:01.890 --> 00:10:04.690
margin of error. The universe appears to be

241
00:10:04.690 --> 00:10:07.410
geometrically flat. If the

242
00:10:07.410 --> 00:10:09.970
universe is truly flat, then in

243
00:10:09.970 --> 00:10:12.850
principle, it would extend infinitely in

244
00:10:12.850 --> 00:10:13.650
all directions.

245
00:10:14.820 --> 00:10:17.140
Avery: Case closed, then, the universe is infinite.

246
00:10:17.780 --> 00:10:20.100
Anna: Not quite. Here's the catch.

247
00:10:20.500 --> 00:10:23.020
We are limited by our observable

248
00:10:23.020 --> 00:10:25.940
horizon. We can only see the part of

249
00:10:25.940 --> 00:10:28.580
the universe from which light has had time to

250
00:10:28.580 --> 00:10:30.500
reach us since the Big Bang.

251
00:10:31.300 --> 00:10:34.140
Avery: The mind just reels at that. If it's truly

252
00:10:34.140 --> 00:10:36.420
infinite, that means that somewhere out

253
00:10:36.420 --> 00:10:39.340
there, an infinite distance away, there's

254
00:10:39.340 --> 00:10:42.180
another solar system exactly like ours, with

255
00:10:42.180 --> 00:10:44.540
another Earth and, and another you and I

256
00:10:44.540 --> 00:10:46.780
having this exact same conversation.

257
00:10:47.980 --> 00:10:50.700
Anna: That's the logical, if unsettling,

258
00:10:50.860 --> 00:10:53.660
conclusion. With an infinite number of

259
00:10:53.660 --> 00:10:56.220
chances, any event with a non zero

260
00:10:56.300 --> 00:10:59.300
probability must occur an infinite

261
00:10:59.300 --> 00:11:02.260
number of times. It pushes the boundaries

262
00:11:02.260 --> 00:11:04.860
of physics into the realm of philosophy.

263
00:11:05.660 --> 00:11:08.580
Avery: Oh, okay, so it's like standing in Kansas. It

264
00:11:08.580 --> 00:11:10.700
looks perfectly flat as far as you can see.

265
00:11:11.020 --> 00:11:13.420
But you know that on a large enough scale,

266
00:11:13.420 --> 00:11:14.460
the Earth is cur.

267
00:11:15.690 --> 00:11:18.690
Anna: That's a perfect analogy. The universe could

268
00:11:18.690 --> 00:11:21.290
be curved on a scale much, much

269
00:11:21.290 --> 00:11:24.290
larger than our observable horizon. It

270
00:11:24.290 --> 00:11:26.970
could be a steer or a saddle so vast

271
00:11:27.210 --> 00:11:29.850
that our little patch of it just looks flat.

272
00:11:30.570 --> 00:11:32.370
Avery: And there's another wrinkle, too, isn't

273
00:11:32.370 --> 00:11:34.490
there? The idea of topology.

274
00:11:35.530 --> 00:11:38.170
Anna: Yes. Even a flat universe

275
00:11:38.330 --> 00:11:41.220
might not be infinite. It could have a

276
00:11:41.220 --> 00:11:44.100
complex topology. For example, it could

277
00:11:44.100 --> 00:11:47.020
be shaped like a donut. If you travel in a

278
00:11:47.020 --> 00:11:49.340
straight line, you eventually end up back

279
00:11:49.340 --> 00:11:52.100
where you started. In that case, the universe

280
00:11:52.100 --> 00:11:54.180
would be flat but finite.

281
00:11:54.980 --> 00:11:57.220
Avery: Have scientists looked for evidence of that

282
00:11:57.220 --> 00:11:59.940
donut shape? For instance, by looking for

283
00:11:59.940 --> 00:12:02.340
repeating patterns in the cosmic microwave

284
00:12:02.340 --> 00:12:04.460
background, as if we were seeing the same

285
00:12:04.460 --> 00:12:06.340
region of space from different directions.

286
00:12:07.340 --> 00:12:10.180
Anna: They have, very carefully. So

287
00:12:10.180 --> 00:12:12.660
far, no such repeating patterns have been

288
00:12:12.660 --> 00:12:15.200
found. While this doesn't rule out a, uh,

289
00:12:15.260 --> 00:12:18.100
finite universe, it does mean that if

290
00:12:18.100 --> 00:12:21.060
the universe is finite, it must be

291
00:12:21.060 --> 00:12:23.420
vastly larger than the part we can see.

292
00:12:24.060 --> 00:12:26.860
So for all practical purposes, it might

293
00:12:26.860 --> 00:12:29.340
as well be infinite from our perspective.

294
00:12:30.140 --> 00:12:32.540
Avery: So in the end we're left without a definitive

295
00:12:32.540 --> 00:12:35.140
answer. Our measurements say flat, which

296
00:12:35.140 --> 00:12:38.140
points towards infinite, but we can't be sure

297
00:12:39.110 --> 00:12:39.670
exactly.

298
00:12:40.150 --> 00:12:42.590
Anna: It's possible that because of the horizon

299
00:12:42.590 --> 00:12:45.430
problem, this is a question we may never

300
00:12:45.430 --> 00:12:48.230
be able to answer for certain. It's one of

301
00:12:48.230 --> 00:12:50.230
the profound limits of cosmology.

302
00:12:51.190 --> 00:12:53.630
Avery: And what a profound place to end our journey

303
00:12:53.630 --> 00:12:56.190
today. From the laws of black holes to the

304
00:12:56.190 --> 00:12:59.190
hardiness of moss, from balloon telescopes to

305
00:12:59.190 --> 00:13:01.870
tilted worlds, and finally to the ultimate

306
00:13:01.870 --> 00:13:04.150
fate and size of the universe itself.

307
00:13:05.160 --> 00:13:07.640
Anna: It really shows you the incredible range of

308
00:13:07.640 --> 00:13:09.880
questions that astronomy seeks to answer.

309
00:13:10.360 --> 00:13:12.120
Thank you all for joining us on, um, this

310
00:13:12.120 --> 00:13:12.840
exploration.

311
00:13:13.160 --> 00:13:15.120
Avery: That's all for this episode of Astronomy

312
00:13:15.120 --> 00:13:17.160
Daily. You can find us wherever you get your

313
00:13:17.160 --> 00:13:19.160
podcasts. And we'll be back next time with

314
00:13:19.160 --> 00:13:21.360
more news from across the universe. Until

315
00:13:21.360 --> 00:13:22.600
then, I'm Avery.

316
00:13:23.000 --> 00:13:25.560
Anna: And I'm Anna. Keep looking up.