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.