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This week in science: Elusive antimatter, a brightening night sky and Fat Bear Week


Our friends from NPR's Short Wave podcast are back with another science news roundup. Aaron Scott and Regina Barber, good to have you both back here.



SHAPIRO: As usual, you've brought us three science stories that have caught your eye. What do you have for us this time?

BARBER: How about light pollution but from satellites?

SCOTT: And a big new finding about antimatter.


BARBER: And one of my favorite animal weeks - Fat Bear Week.

SHAPIRO: Uh, so many of us do love Fat Bear Week. Let's start with light pollution because that's something I'm familiar with. I think we've all heard about it from cities and houses, and now it's coming from satellites. Explain that.

BARBER: Yeah. Satellites also cause light pollution because they reflect the sunlight. They look like stars, and the night sky is filling up with them.

SCOTT: And that's because, of course, communication companies are promising reliable internet to the most remote places by launching these networks of satellites. I mean, I'm sure that you've heard of Starlink from SpaceX.

SHAPIRO: Yes - owned by Elon Musk.

SCOTT: Yes. They currently have about 5,000 satellites in space with plans for thousands more. And that is just one company. The brightness from all these satellite networks can ruin data for ground-based telescopes.

BARBER: And I spoke with observational astronomer Jeremy Tregloan-Reed. He's a co-author on a new paper in Nature, focusing on measuring the brightness of the biggest commercial satellite in space, BlueWalker 3. He says only seven stars in the sky are brighter.

SCOTT: And for a sense of scale here, BlueWalker 3 is 64 times bigger than the first generation Starlink satellites. And AST SpaceMobile, the company behind BlueWalker, wants to put up more of them.

SHAPIRO: Beyond the impact for astronomers studying the cosmos and stargazers lying on a blanket staring up at the sky, are there other implications?

BARBER: Yeah. Fast internet doesn't just come at the cost of science. Some researchers are worried that these satellites might impact humanity's safety.

SHAPIRO: By falling out of the sky?

BARBER: No, but by what it gets in the way of. The light reflected by these satellites is making the night sky brighter, especially at dusk and dawn, which happens to be the time astronomers hunt for dim, potentially dangerous asteroids.

SCOTT: Yeah, so these bright satellites are interfering with our ability to find rogue space rocks.

SHAPIRO: Oh, no.

SCOTT: (Laughter).

SHAPIRO: Is there any effort to regulate this and prevent us from being crashed into by an asteroid?

SCOTT: Yeah, Ari, not from governments. There is a group made up of experts called the International Astronomical Union that does have recommendations for how bright these satellites can be without strongly affecting science. The union, of course, can't legally require companies to do anything. But they do lobby, and they do a pretty good job working with industry so that they know how to modify future satellites.

BARBER: Yeah. So SpaceX and AST SpaceMobile are already modifying satellites to be less bright, but it might not be enough. So Jeremy hopes that public pressure might help.

SHAPIRO: OK. Let's move on to topic two - antimatter. This is taking us one step closer to solving one of the great mysteries of the universe. I'm intrigued.

SCOTT: Yes, indeed. So scientists at CERN, the giant research facility in Europe, they have officially proven that antimatter obeys the laws of gravity.

SHAPIRO: This is where I reveal I don't actually know what antimatter is.

SCOTT: Fair.

SHAPIRO: I've heard the word. I've seen it in sci-fi movies. That's as far as it goes for me.

BARBER: Yeah. Let me help you out. The universe we know of - our planet, you, me, Aaron - we're all made up of matter. But since the 1920s, scientists have known that every particle of matter, you know - protons, neutrons, electrons - they have a corresponding antiparticle. And what sci-fi gets right is that when matter and antimatter collide, they explode and cancel each other out.

SCOTT: So Ari, this leads to our big mystery because scientists believe that at the beginning of the universe, there was both matter and antimatter. But instead of canceling each other out, the matter stuck around while the antimatter vanished. We don't know what happened to it. But one fringe theory says that maybe gravity affects it differently and somehow pushed it out of the way.

BARBER: Now, Ari, the fringe idea totally contradicts Einstein's general theory of relativity. So you can guess how scientists were betting.

SHAPIRO: Not against Einstein.


SCOTT: No. No. Jeffrey Hangst, who leads this collaboration that published this research in the journal Nature last week, he says they, of course, were thinking Einstein was right, but they couldn't know for sure until they tested it.

JEFFREY HANGST: Antimatter is this mysterious stuff, and we don't know what happened in the origin of the universe. Gravity is another big mystery today. So it's very compelling to be able to do this experiment with two things that had big, open questions.

SHAPIRO: What was the experiment? How did they test all of this?

SCOTT: Yeah, so they use cutting-edge technology to make antihydrogen atoms - like you do. And then they suspended them inside this magnetic force field in a very, very cold vacuum.

SHAPIRO: Oh, just like a typical day at work, huh?

BARBER: At CERN, yeah. Then they turned off the magnetic field, and they counted how many atoms fell due to Earth's gravity.

SCOTT: And it turns out that 80% of these antimatter atoms fell, which matches the rate that normal atoms fall. So antimatter behaves just like regular matter when it comes to gravity. And that means that gravity likely doesn't explain what happened to all that antimatter at the dawn of the universe.

SHAPIRO: So Einstein was right, and I'm picturing that famous photograph of him sticking out his tongue at his haters.

SCOTT: Indeed. Indeed. How does he do it?

SHAPIRO: All right. I may not understand antimatter, but I can understand a fat bear.


SHAPIRO: Last but not least, tell us about Fat Bear Week.

BARBER: Yeah, Fat Bear Week - so this is an event started in 2014 by rangers from Katmai National Park and Preserve in Alaska. It just kicked off on Wednesday. Think of it like an online March Madness tournament, except the winner is a very, very fat bear.

SCOTT: Yes. Our competitors are 12 brown bears picked by rangers. And these bears gather every year at Brooks River in Katmai to gorge on salmon beginning around late June. And they are all trying to do one thing, and that is get super fat to survive the coming winter hibernation.

BARBER: And just to give you a sense of how fat we're talking about, these adult male bears can grow from 700 pounds to 1,200 pounds.

SHAPIRO: I looked at the website that has before-and-after photos, and the difference is shocking.

SCOTT: It's incredible. And that's because hibernation eats up a lot of weight. There is a lot that is going on as that bear slumbers. So Ari, are you ready for some hibernation science facts?

SHAPIRO: Never been more ready.


SCOTT: OK. No. 1, when hibernating, a bear's heart and respiratory rate drop dramatically - they average only one breath per minute with a heart rate of 8- to 10 beats per minute.


BARBER: Bears don't eat, drink, urinate or defecate while in their winter shelter or den. Instead, their fat is metabolized to produce water and food. So remarkably, bears are able to hold onto their muscle mass and bone density when they finally emerge from hibernation in the spring.

SHAPIRO: OK, I'm looking through the gallery, and I have to say it does not seem fair to me that some of these bears get names like Chunk and Grazer...

SCOTT: Uh-huh.

SHAPIRO: ...And others have to settle for being Bear 901. How does the winner ultimately get picked?

SCOTT: Yeah, so people go to fatbearweek.org, and they vote on their favorite bear. And the winner gets crowned next week on Fat Bear Tuesday.

BARBER: I'm all-in on bear number 32, also known as Chunk. He has a, quote, "low-hanging belly and ample hindquarters," unquote.

SHAPIRO: That's what it says in his Hinge profile.

BARBER: (Laughter).

SCOTT: Yes, ample hindquarters on Hinge. He also has my vote because he is described as enigmatic.

BARBER: But of course, they're all winners. This is just a fun way to bring more attention to these incredible bears and the Katmai ecosystem.

SHAPIRO: Well, as a responsible journalist, I'm not going to take sides in this debate.

BARBER: (Laughter).

SCOTT: No. Objectivity.

SHAPIRO: Regina Barber and Aaron Scott from NPR's science podcast Short Wave, where you can learn about new discoveries, everyday mysteries and the science behind the headlines. Thank you both so much.

BARBER: Thank you, Ari.

SCOTT: Thanks, Ari.

(SOUNDBITE OF DAMIEN RICE SONG, "VOLCANO") Transcript provided by NPR, Copyright NPR.

NPR transcripts are created on a rush deadline by an NPR contractor. This text may not be in its final form and may be updated or revised in the future. Accuracy and availability may vary. The authoritative record of NPR’s programming is the audio record.

Aaron Scott
Aaron Scott (he/him) is co-host of NPR's daily science podcast, Short Wave. The show is a curiosity-fueled voyage through new discoveries, everyday mysteries and the personal stories behind the science.
Regina G. Barber
Regina G. Barber is Short Wave's Scientist in Residence. She contributes original reporting on STEM and guest hosts the show.