Learn how atomic clocks and GPS clocks work, with help from the engineer who made GPS clocks possible: Hugo Fruehauf. But first, you’ll learn about how Harvard researchers finally figured out why stress can turn your hair gray.
Learn how atomic clocks and how GPS clocks work, with help from the engineer who made GPS clocks possible: Hugo Fruehauf. But first, you’ll learn about how Harvard researchers finally figured out why stress can turn your hair gray.
Why Stress Turns Hair Gray by Grant Currin
Additional resources from Hugo Fruehauf:
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Find episode transcript here: https://curiosity-daily-4e53644e.simplecast.com/episodes/how-gps-clocks-work-w-hugo-fruehauf-and-why-stress-turns-hair-gray
CODY: Hi! You’re about to get smarter in just a few minutes with Curiosity Daily from curiosity-dot-com. I’m Cody Gough.
ASHLEY: And I’m Ashley Hamer. Today, you’ll learn how GPS clocks work, from the engineer who made GPS clocks in the first place: Hugo Fruehauf [FROO-hoff]. But first, you’ll learn about how researchers finally figured out a scientific explanation for why stress can turn your hair gray.
CODY: Let’s satisfy some curiosity.
We’ve known for a long time that stress can make your hair go gray or white — think Barack Obama, George W. Bush, or Rogue from X-Men. But for a long time, scientists didn’t have any idea why. Well, a huge team of researchers led by Harvard University has just figured it out, and it involves our old friend the flight-or-flight response.
The researchers' first job was to figure out which body system is responsible for translating stressful situations into gray hair. Their first thought was that the immune system might be attacking itself, so they got their hands on some mice without immune cells and put them under stress. When those mice turned gray, the researchers knew that wasn’t the cause.
Then they turned to the infamous stress hormone cortisol. They removed the adrenal glands from a new batch of mice and subjected them to stress. Again, they went gray.
Then they turned to the sympathetic nervous system. It seemed like a good candidate because it contains a huge network of neurons that reach into every hair follicle in the body. After more tests on more mice, the researchers finally had their culprit.
Here’s what happens: a hair follicle contains specialized stem cells. Stem cells are a kind of cell that can turn into any of a number of different cell types. When a hair is growing, some of those stem cells convert into cells that produce melanin, which is a pigment responsible for hair color. Some people’s nervous systems respond to incredibly stressful situations by releasing huge amounts of the neurotransmitter norepinephrine. That norepinephrine tells all of those all-purpose stem cells to specialize into pigment-producing cells and then migrate away from where they’re needed.
The follicles keep growing new hairs but the supply of pigment-producing cells have dried up, so the new hairs are white or gray.
It’s like using all of your sunscreen on the first day of a tropical vacation. Now you’re definitely gonna turn a color you don’t want.
This is just another bullet on the long list of ways that stress affects the body. Hopefully the new insights from this study will help scientists develop new therapies and tactics to ease the physical toll of stress — and maybe save some presidential hairdos in the process.
If you look at your cell phone right now, chances are, you can tell me what time it is — with astonishing accuracy. Phones and devices all around the world are synced up to within a fraction of a second thanks to the innovation we call GPS, the Global Positioning System. And part of that is thanks to the fact that Hugo Fruehauf [FROO-hoff] developed a highly accurate, miniaturized atomic clock, which became a foundational component of GPS. Hugo’s going to explain how GPS clocks work, but first, here’s Hugo on what an atomic clock even is.
[CLIP 1:04]
Okay, so like Hugo said, that’s a bit of a simplification, but hopefully it gives you a good idea of why they’re so accurate. Atomic clocks used to be really big and really expensive. So it was a big deal figuring out how to make those clocks small enough to launch into space, let alone get them to work properly while being exposed to heavy radiation. But obviously, Hugo and his colleagues got everything working right. So let’s get into how GPS clocks work. Hugo told us to imagine you’re flying three kites at the same time. You pull the strings tight, so there’s no slack. Those kites are stuck in the same place, so you can’t really move around, because there’s no more slack on the strings. Now pretend those kites are GPS satellites, and they’re sending you signals.
[CLIP 2:37]
You heard that right: these clocks sync up to within a BILLIONTH of a second. Sounds simple, right? Just have a few satellites with atomic clocks triangulate your latitude, longitude, and altitude, and call it a day? Well… here’s Hugo with why it wasn’t quite THAT easy.
[CLIP 1:30]
Again, Hugo Fruehauf is one of the inventors of GPS. And if you use your phone as an alarm clock, then he’s pretty much the guy you can thank for getting to work on time every day. Hugo was one of four pioneers who received the Queen Elizabeth Prize for Engineering in December, which is the world’s most prestigious engineering accolade. We have links to learn more about Hugo and the prize in today’s show notes, and next week Hugo will be back one more time to talk about the lasting legacy of GPS.
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CODY: Today’s first story was written by Steffie Drucker, and edited by Ashley Hamer, who’s the managing editor for Curiosity Daily.
ASHLEY: Today’s episode was scripted, produced, and edited by Cody Gough.
CODY: Join us again tomorrow to learn something new in just a few minutes.
ASHLEY: And until then, stay curious!