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

0:00 Avery: Hello, and ah, welcome to Astronomy Daily,

0:03 the podcast that brings the cosmos down to

0:05 Earth. I'm Avery, and as always, I'm

0:08 here with the brilliant Anna.

0:10 Anna: Hello, Avery, and hello to all our

0:13 listeners. We have a fascinating lineup today

0:16 covering everything from cosmic giants

0:18 to microscopic survivors.

0:21 Avery: That's right. We'll be talking about a major

0:24 confirmation of a Stephen Hawking theory.

0:27 Moths that survived the vacuum of space.

0:29 A telescope on a balloon. A planet that's

0:32 orbiting completely off kilter. And we'll end

0:35 by tackling one of the biggest questions out

0:37 there. Is the universe infinite?

0:40 Anna: It's a packed episode.

0:42 Shall we start with the giants?

0:44 Avery: Let's do it. Our first story is a big

0:47 one. Two of the greatest minds in physics,

0:49 Stephen Hawking and Albert Einstein,

0:52 both had some of their most fundamental

0:54 predictions confirmed by a single cosmic

0:57 event.

0:58 Anna: This involves the collision of two black

1:00 holes. Using gravitational wave

1:03 observatories, scientists got their clearest

1:05 observation yet of such a merger.

1:08 Avery: And the first big confirmation relates to

1:11 Hawking's area theorem. Um, he predicted that

1:13 the surface area of a black hole, its event

1:16 horizon can never, ever shrink. It

1:19 can only stay the same or grow.

1:22 Anna: Right. It's a law of black hole mechanics.

1:25 And in this merger, they measured the surface

1:27 area of the two original black holes and

1:30 compared it to the new, larger one that

1:33 formed.

1:33 Avery: And?

1:34 Anna: And the new surface area was indeed

1:37 greater than the sum of the two initial ones.

1:40 Hawking was right.

1:42 Avery: It's just incredible to see a theoretical

1:44 prediction made decades ago proven so

1:47 precisely. But that wasn't all they saw, was

1:50 it?

1:50 Anna: No, it wasn't. The signal was so

1:53 clear that they could observe the ring down

1:56 of the new black hole. Think of it like

1:58 striking a bell.

1:59 Avery: Mhm. The ringing.

2:01 Anna: Exactly. The new black hole wobbled

2:04 and settled into its final shape, sending out

2:07 gravitational waves that faded over time,

2:09 just like the sound of a bell. The specific

2:12 frequencies and decay patterns of that ring

2:14 down matched the predictions of Einstein's

2:17 general theory of relativity perhaps

2:19 perfectly.

2:20 Avery: So in one event, we get a check mark for

2:22 Hawking and a check mark for Einstein.

2:25 And this new object they observed is called a

2:28 Kerr black hole, right?

2:30 Anna: That's correct. A Kerr black hole is one that

2:32 is rotating. Since the two smaller black

2:35 holes were spiraling around each other, the

2:38 resulting merged black hole inherited that

2:40 spin. It's the type of black hole we expect

2:43 to be common in the universe.

2:45 Avery: Wow. What a powerful confirmation of our

2:48 understanding of gravity and the universe.

2:50 From the colossal to the well to the very,

2:53 very small.

2:54 Our next story is almost the polar opposite.

2:57 Anna: It really is. This story comes from

3:00 the International Space Station, but it's not

3:03 about the astronauts inside. It's about

3:06 something that was living on the outside.

3:08 Avery: On the outside? Fully exposed to space.

3:12 Anna: Fully exposed. Scientists placed moss

3:15 spores in a container on an external platform

3:17 of the iss. For nine months, these

3:20 spores endured the vacuum of space,

3:23 extreme temperature swings, and the full

3:26 force of cosmic radiation.

3:28 Avery: That sounds like a recipe for total

3:29 destruction. I can't imagine anything

3:32 surviving that.

3:33 Anna: That's what makes this so astonishing. When

3:36 they brought the spores back to Earth, a high

3:38 percentage of them were still able to

3:40 germinate and grow.

3:42 Avery: No way. They just started growing

3:44 again after nine.

3:46 Anna: Months in raw space as if nothing had

3:49 happened. It speaks to the incredible

3:51 resilience of life. Organisms like

3:54 this, known as extremophiles, really

3:57 push the boundaries of what we thought was

3:59 possible.

4:00 Avery: This has huge implications for theories like

4:02 panspermia, doesn't it? The idea that life

4:05 could travel between planets on asteroids or

4:07 comets.

4:08 Anna: It certainly makes it seem more plausible. If

4:11 simple spores can survive the harshness of

4:14 space for extended periods, it suggests

4:17 that the building blocks of life might be

4:19 tougher and more widespread than we ever

4:21 imagined.

4:23 Avery: From survivors in space to a new way of

4:25 seeing in space.

4:27 Our next story involves a very unusual

4:29 observatory. We're not talking about a

4:32 mountaintop or a satellite, but a telescope

4:35 dangling from a giant balloon.

4:37 Anna: This is the Excalibur mission. And while a

4:40 balloon might sound low tech, it's actually

4:43 an incredibly clever way to do astronomy.

4:46 Avery: It carries a telescope up to about

4:48 130,000ft, which is above

4:51 99% of Earth's atmosphere. This

4:54 gives it a much clearer view, especially for

4:56 the kind of light it's designed to see. High

4:59 energy X rays.

5:00 Anna: Mm X rays that are blocked by our

5:03 atmosphere. And Excalibur isn't just taking

5:06 pictures. Its key function is to measure

5:09 the polarization of these X rays.

5:11 Avery: Can you break that down for us? What does

5:13 measuring polarization actually tell?

5:16 Anna: You think of light as a wave.

5:19 Usually those waves are oriented randomly.

5:22 Polarization is like filtering the light, so

5:25 you only see waves oriented in a specific

5:27 direction. For astronomers, the. The way X

5:30 rays are polarized tells them about the

5:33 powerful and complex magnetic fields

5:36 near their source.

5:38 Avery: So it's a way to map out invisible

5:40 magnetic structures. And they pointed this

5:43 thing at some pretty famous cosmic objects,

5:45 right?

5:46 Anna: They did. The mission focused on two

5:49 main the Crab Nebula, which is the

5:52 remnant of a supernova, and Cygnus

5:54 X1, a famous system containing a

5:57 black hole that's feeding off a companion

6:00 star.

6:01 Avery: And by measuring the X ray polarization.

6:04 They are getting new insights into the

6:06 physics of the neutron star powering the Crab

6:09 Nebula and the geometry of the material

6:12 swirling into the black hole in Cygnus X1.

6:15 It's a whole new layer of information.

6:17 Anna: It really is. Balloon based

6:20 astronomy provides a fantastic, cost

6:23 effective way to get above the atmosphere and

6:25 test new technologies.

6:27 Okay, from new views to new mysteries,

6:30 our next story presents a real puzzle.

6:33 Avery: Yeah, this one is a head scratcher.

6:36 Astronomers have found an exoplanet system

6:38 named TOI 3884

6:41 where things just don't add up.

6:43 Anna: The planet itself is a super

6:45 neptune, larger than Neptune, but smaller

6:48 than Saturn. It orbits its star quite

6:51 closely. But that's not the strange part. The

6:54 strangeness lies in its orbit.

6:57 Avery: It's wildly tilted. Most planets

7:00 in a solar system form in a flat disk,

7:03 so they tend to orbit in the same plane

7:05 aligned with the star's equator. This

7:08 one is misaligned by about

7:11 62 degrees. It's orbiting on

7:14 a crazy diagonal path.

7:16 Anna: Right. A 62 degree tilt is

7:19 extreme. Usually to get an orbit that

7:22 tilted, you need a powerful gravitational

7:24 nudge from m, another massive object in the

7:27 system. Like a giant planet farther out

7:30 or a, uh, companion star.

7:32 Avery: And the mystery is there isn't one.

7:35 Scientists have looked and they can't find

7:37 anything massive enough nearby to explain

7:40 how this planet got knocked so far off

7:43 kilter.

7:44 Anna: Precisely. The usual suspects are all

7:47 missing. It leaves them with some

7:49 unconventional theories. Perhaps the

7:51 stars protoplanetary disk was tilted

7:54 from the very beginning by a passing star

7:57 early in its history. Or maybe there was

7:59 another planet that knocked this one aside

8:02 and then got ejected from the system

8:04 entirely.

8:05 Avery: A, uh, cosmic hit and run.

8:07 Anna: Exactly.

8:09 Avery: And that theory of an ejected planet, A, uh,

8:11 cosmic hit and run. Why is that

8:14 so difficult to prove?

8:16 Anna: Because the getaway car is long gone

8:19 and completely invisible. A planet

8:21 ejected from its solar system would become a

8:24 rogue planet, drifting cold and dark through

8:27 interstellar space. There's no star to light

8:29 it up. So finding it, let alone tracing

8:32 it back to its home system, is practically

8:35 impossible with our current technology.

8:37 Avery: So scientists have a pretty big mystery.

8:40 Anna: On their hands, essentially.

8:42 For now, it's an open case file.

8:46 It's a reminder that planet formation is a

8:49 chaotic and complex process. And

8:51 our own solar system systems neat alignment

8:54 might be less common than we think.

8:57 Avery: Speaking of things being less common than we

8:59 think, our final story tackles maybe the

9:02 biggest astronomical question of Is

9:05 the universe infinite?

9:07 Anna: It's a question that feels almost

9:09 philosophical, but scientists are trying

9:12 to answer it with actual measurements.

9:15 The Key lies in determining the overall

9:18 shape or geometry of the universe.

9:22 Avery: And their best tool for that is the cosmic

9:24 microwave background, or cmb.

9:26 That's the leftover heat from the Big Bang,

9:29 which fills all of space.

9:32 Anna: Correct. By studying the tiny

9:34 temperature fluctuations in the cmb,

9:37 cosmologists can measure the universe's

9:40 geometry. There are three basic

9:42 possibilities. It could be closed,

9:46 like the surface of a sphere, open

9:49 like the surface of a saddle, or flat,

9:52 like a sheet of paper.

9:54 Avery: And so far, every measurement we've made

9:56 points to one answer.

9:58 Anna: Flat to within a very small

10:01 margin of error. The universe appears to be

10:04 geometrically flat. If the

10:07 universe is truly flat, then in

10:09 principle, it would extend infinitely in

10:12 all directions.

10:14 Avery: Case closed, then, the universe is infinite.

10:17 Anna: Not quite. Here's the catch.

10:20 We are limited by our observable

10:23 horizon. We can only see the part of

10:25 the universe from which light has had time to

10:28 reach us since the Big Bang.

10:31 Avery: The mind just reels at that. If it's truly

10:34 infinite, that means that somewhere out

10:36 there, an infinite distance away, there's

10:39 another solar system exactly like ours, with

10:42 another Earth and, and another you and I

10:44 having this exact same conversation.

10:47 Anna: That's the logical, if unsettling,

10:50 conclusion. With an infinite number of

10:53 chances, any event with a non zero

10:56 probability must occur an infinite

10:59 number of times. It pushes the boundaries

11:02 of physics into the realm of philosophy.

11:05 Avery: Oh, okay, so it's like standing in Kansas. It

11:08 looks perfectly flat as far as you can see.

11:11 But you know that on a large enough scale,

11:13 the Earth is cur.

11:15 Anna: That's a perfect analogy. The universe could

11:18 be curved on a scale much, much

11:21 larger than our observable horizon. It

11:24 could be a steer or a saddle so vast

11:27 that our little patch of it just looks flat.

11:30 Avery: And there's another wrinkle, too, isn't

11:32 there? The idea of topology.

11:35 Anna: Yes. Even a flat universe

11:38 might not be infinite. It could have a

11:41 complex topology. For example, it could

11:44 be shaped like a donut. If you travel in a

11:47 straight line, you eventually end up back

11:49 where you started. In that case, the universe

11:52 would be flat but finite.

11:54 Avery: Have scientists looked for evidence of that

11:57 donut shape? For instance, by looking for

11:59 repeating patterns in the cosmic microwave

12:02 background, as if we were seeing the same

12:04 region of space from different directions.

12:07 Anna: They have, very carefully. So

12:10 far, no such repeating patterns have been

12:12 found. While this doesn't rule out a, uh,

12:15 finite universe, it does mean that if

12:18 the universe is finite, it must be

12:21 vastly larger than the part we can see.

12:24 So for all practical purposes, it might

12:26 as well be infinite from our perspective.

12:30 Avery: So in the end we're left without a definitive

12:32 answer. Our measurements say flat, which

12:35 points towards infinite, but we can't be sure

12:39 exactly.

12:40 Anna: It's possible that because of the horizon

12:42 problem, this is a question we may never

12:45 be able to answer for certain. It's one of

12:48 the profound limits of cosmology.

12:51 Avery: And what a profound place to end our journey

12:53 today. From the laws of black holes to the

12:56 hardiness of moss, from balloon telescopes to

12:59 tilted worlds, and finally to the ultimate

13:01 fate and size of the universe itself.

13:05 Anna: It really shows you the incredible range of

13:07 questions that astronomy seeks to answer.

13:10 Thank you all for joining us on, um, this

13:12 exploration.

13:13 Avery: That's all for this episode of Astronomy

13:15 Daily. You can find us wherever you get your

13:17 podcasts. And we'll be back next time with

13:19 more news from across the universe. Until

13:21 then, I'm Avery.

13:23 Anna: And I'm Anna. Keep looking up.