text: This week in science: squid fabric, a growing Everest, and the mystery of lightning
  JUANA SUMMERS, HOST:
  I'm here with the hosts of NPR's science podcast, Short Wave, Regina Barber and Emily Kwong. And they're here for our regular science news roundup. Hi to both of you.
  REGINA BARBER, BYLINE: Hey.
  EMILY KWONG, BYLINE: Hey, Juana.
  SUMMERS: So I know that y'all have again brought us three science stories that caught your attention this week. Tell us what they are.
  BARBER: A spy plane discovery that could tell us about the process that forms lightning.
  KWONG: And behind door No. 2, how Mount Everest is getting taller and a nearby river gorge may be contributing.
  BARBER: And squids are inspiring clothing that can change with the weather.
  SUMMERS: OK. I have so many questions here, but we've got to start with the lightning.
  BARBER: Yeah. All right. Well, even though thunderstorms generate lightning all the time - right? - we don't actually know how lightning forms.
  SUMMERS: Wait. What?
  BARBER: No, not at all. But some scientists have recently conducted experiments to help solve that mystery.
  KWONG: Basically, they flew a NASA ER-2 - that's, like, a research version of a spy plane - over several tropical thunderstorms. And it didn't detect radio or optical signals, but it did detect a significant amount of gamma radiation.
  SUMMERS: Gamma radiation. Isn't that what turns Bruce Banner into the Hulk?
  BARBER: Yes, and me into the Hulk. It's also the shortest wavelength and the most energy of any rays in the electromagnetic spectrum. You can find them in places like neutron stars and regions around black holes. And on Earth, you can find them in thunderstorms. And we've known that for a while, but now researchers have observed how they build up. They detect gamma radiation at all kinds of levels.
  JOSEPH DWYER: Right before the lightning, you're starting to get all these gamma rays coming out, which says the fields must be pretty large. In fact, there's so much radiation coming out, there's - large currents are being generated, which is probably altering the electric fields inside the thunderstorm. And so that could help the thunderstorm build up the fields to get lightning started.
  BARBER: That's Joseph Dwyer. He's a professor of physics and astronomy at the University of New Hampshire. And he wasn't involved in this research, but he's excited about this discovery.
  SUMMERS: Y'all, I've got to be honest here. This all sounds just a little - I don't know - dangerous to me. Do I need to be concerned about flying through a thunderstorm and getting shot up by gamma rays?
  BARBER: Fair question. No, you don't need to worry. OK, given the amount of radiation being detected, Joseph says if your plane was hit by gamma rays, it wouldn't hurt you.
  DWYER: I'd say, you know, if you ever are in an airplane that ends up inside a thunderstorm, the radiation dose will be the last thing you need to worry about. You know, if a piece of luggage fell out of the overhead bin, hit you in the head and they took you to the emergency room and X-rayed your head, you'd probably get a bigger dose from the X-rays than the gamma rays coming out.
  SUMMERS: OK. That's minorly reassuring, but I'll move on.
  KWONG: Minor (laughter).
  SUMMERS: Let's talk about Mount Everest. It is already Earth's highest mountain above sea level, and you mean to tell me it's getting taller.
  BARBER: It is. Mount Everest, also known as Qomolangma in Tibetan or Sagarmatha in Nepali - the mountain has been growing for millennia. It has grown three feet since 1955.
  KWONG: And part of the reason is definitely plate tectonics. As the Indian plate slips under the Eurasian plate, it uplifts the Himalayas. Earthquakes can reduce that height in an instant, but there may be other factors.
  SUMMERS: Like what?
  KWONG: Like isostatic rebound.
  SUMMERS: Come again?
  KWONG: It's a phenomenon in geology that may be changing the height of Everest.
  BARBER: So picture this - Everest, tall.
  SUMMERS: Got it.
  BARBER: Also surrounded by rivers.
  SUMMERS: Got it.
  BARBER: Some scientists theorize that 89,000 years ago, one of those rivers, the Arun, was captured by a larger river nearby, the Kosi. And this created a ton of erosion, such that the Arun River has been washing away earth and sediment and carving out a deep, deep gorge. Here's geologist Matthew Fox at University College London.
  MATTHEW FOX: And so when we have this focused erosion along the length of the Arun, the surrounding areas rebound to account for that change in weight of the mountains.
  KWONG: So that's isostatic rebound, when a section of the Earth's crust slowly flexes upward because of the pressure of the liquid magma below.
  SUMMERS: So how much is this effect contributing to Everest getting taller?
  KWONG: That is a question geologists are debating. A study published in the journal Nature Geoscience suggests this isostatic rebound over 89,000 years may have raised Mount Everest by 15 to 50 meters, which is 50 to 160 feet.
  SUMMERS: That is a lot.
  KWONG: Yeah. It is. However, some geologists told me they don't agree with the finding. Though isostatic rebound in this river area is real, Mike Searle at the University of Oxford told me that tectonic plate activity appears to be what's primarily driving Everest's growth spurt.
  SUMMERS: OK, super-interesting. Gina, you got to take us home here. You mentioned something earlier about squids and clothing that changes with the weather.
  BARBER: Yeah. So the thing I love about squids, other than that they're delicious, is that they can camouflage themselves with chromatophores, these little organs in their skin. So when squids move in a certain way, the stretching of their skin makes these chromatophores expand and contract, and this affects how light is reflected by or transmitted through it. This changes how the skin looks.
  KWONG: Yeah. It's so fancy and cool. And materials scientists at UC Irvine decided to take a cue from this process. They created a material that can expand and contract. But instead of blocking or transmitting just light, this can trap and transfer heat. They published their results in APL Bioengineering this week.
  SUMMERS: OK, trapping or transferring heat. Explain how exactly they do that.
  KWONG: All right. You know those silver emergency blankets...
  KWONG: ...For, like, camping or running?
  SUMMERS: Yeah, and running. Yeah.
  KWONG: Yes. OK, and they reflect your body heat back to you. Those use aluminum. This squid fabric uses copper, and it actually looks like a piece of cloth.
  BARBER: Yeah, so that's where the innovation comes in. They created this cloth-like material that can stretch. It's breathable. It's washable. It can be integrated with any fabric. So how it works is that when it's stretched, the copper lining breaks apart to let heat escape. And when the fabric is unstretched, the copper lining comes back together, meaning you have some, like, control over how warm or cool the material keeps you, whether you, like, cinch it up tighter or looser. Here is materials scientist Alon Gorodetsky, and his lab created this prototype.
  ALON GORODETSKY: A good way to visualize it is to think of a mirror and imagine breaking it into shards. And you can look - when all those shards are together, you can still see the reflection. But when you move them apart - right? - you know, some of the light is going to go through the mirror. And that's essentially what we're doing.
  BARBER: Alon says the next step with this squid-inspired fabric is to create bigger pieces of it. Now they just have a prototype of a sleeve. So more work needs to be done before this material can go to market.
  SUMMERS: That's Emily Kwong and Regina Barber from NPR's science podcast, Short Wave, where you can catch new discoveries, everyday mysteries and the science behind the headlines. Thanks to both of you.
  BARBER: Thank you, Juana.
  KWONG: Thank you, Juana.
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