Learn about why you’re almost completely made up of empty space; what defines a second of time; and where you can watch the Lyrid meteor shower this Tuesday. In this podcast, Cody Gough and Ashley Hamer discuss the following stories from Curiosity.com to help you get smarter and learn something new in just a few minutes: You're Almost Completely Made Up of Empty Space — https://curiosity.im/2Gq85KQ Here's How You Can Watch the Lyrid Meteor Shower in 2019 — https://curiosity.im/2GcOP3e Additional resources discussed: Why is a day divided into 24 hours? (Intermediate) | Astronomy Department at Cornell University — http://curious.astro.cornell.edu/physics/161-our-solar-system/the-earth/day-night-cycle/761-why-is-a-day-divided-into-24-hours-intermediate Why are there 24 hours in a day? | ABC Science — http://www.abc.net.au/science/articles/2011/11/15/3364432.htm Using Particle Physics for Measurement Shows Just How Far Measurement Has Come | Curiosity.com — https://curiosity.im/2GpdZfj If you love our show and you're interested in hearing full-length interviews, then please consider supporting us on Patreon. You'll get exclusive episodes and access to our archives as soon as you become a Patron! https://www.patreon.com/curiositydotcom Download the FREE 5-star Curiosity app for Android and iOS at https://curiosity.im/podcast-app. And Amazon smart speaker users: you can listen to our podcast as part of your Amazon Alexa Flash Briefing — just click “enable” here: https://curiosity.im/podcast-flash-briefing.
Learn about why you’re almost completely made up of empty space; what defines a second of time; and where you can watch the Lyrid meteor shower this Tuesday.
In this podcast, Cody Gough and Ashley Hamer discuss the following stories from Curiosity.com to help you get smarter and learn something new in just a few minutes:
Additional resources discussed:
If you love our show and you're interested in hearing full-length interviews, then please consider supporting us on Patreon. You'll get exclusive episodes and access to our archives as soon as you become a Patron! https://www.patreon.com/curiositydotcom
Download the FREE 5-star Curiosity app for Android and iOS at https://curiosity.im/podcast-app. And Amazon smart speaker users: you can listen to our podcast as part of your Amazon Alexa Flash Briefing — just click “enable” here: https://curiosity.im/podcast-flash-briefing.
Find episode transcript here: https://curiosity-daily-4e53644e.simplecast.com/episodes/youre-almost-entirely-empty-space-what-defines-seconds-and-the-lyrid-meteor-shower
CODY: Hi! We’re here from curiosity-dot-com to help you get smarter in just a few minutes. I’m Cody Gough.
ASHLEY: And I’m Ashley Hamer. Today, you’ll learn about why you’re almost completely made up of empty space; and, where you can watch the Lyrid meteor shower this Tuesday. We’ll also answer a listener question about what defines a second.
CODY: Let’s satisfy some curiosity.
You're Almost Completely Made Up of Empty Space — https://curiosity.im/2Gq85KQ (Cody)
Wanna hear something trippy? You’re almost completely made up of empty space. In fact, a lot of the matter around us is empty space. As in, 99.99-99-999 percent of all of the matter around us. [ad lib possible]
CODY: Here’s the deal. Everything around us is made up of atoms, tiny particles with a nucleus surrounded by electrons. These tiny particles are filled with energy, but they’re surrounded by quite a bit of empty space. If you took the empty space out of every human on earth, you could compress the entire human population down to an object smaller than a sugar cube. Obviously, though, things still feel solid, right? The headphones you’re wearing, the car you’re driving in, the thing you’re standing on or sitting in. And that’s because of just what’s in that empty space. See, atoms aren't stagnant particles; they're filled with energy and surrounded by electrons that are constantly buzzing around in a sort of cloud. No two electrons can exist in the same space at the same time. This means that if you wanted to try and walk through a wall, which again is mostly empty space, your electrons and the wall's electrons would have to exist in the same space, making it impossible. Here’s another way to think of it: picture a fan with rapidly spinning blades. There could still be a lot of empty space between those blades, but it stays the same size. That space doesn’t change in volume, but it DOES change in position. And it does so really quickly, so if you stick your hand in there, you’re gonna get whacked by the fan. Atoms work the same way: the orbiting electrons resist being pushed out of their orbits. That’s why the empty space inside atoms can’t be filled with other atoms. There’s one more reason why you can’t fit one atom into another atom, though, and that comes down to quantum mechanics. Electrons are known as point sources, or, a source of energy that has a negligible dimension. This means that electrons have no volume, but they do have a wave function whose energy occupies the space. And thanks to the laws of quantum mechanics, that wave function doesn't just occupy one point — it's everywhere in the empty space at the same time. Basically, that means that if you’re gripping your phone or your steering wheel right now, you’re not actually touching it; what you’re feeling and interpreting as touch is actually just the electromagnetic force from the electrons in YOUR atoms pushing back against the electrons in that object’s atoms. And yes: this means that you've never actually touched anything in your life. You're actually floating just above the chair you're sitting on thanks to incredibly small electromagnetic forces. Isn’t physics fun?
Listener Question — What’s a second? (Ashley)
ASHLEY: We got a listener question from Muhammad Shifaz. If that name sounds familiar, that’s because he gets an executive producer credit on our show every week! Thanks Muhammad! Anyway, here’s his question: What’s a second? Someone couldn’t have just made a moving object like a ticking hand in a clock and said 60 ticks is 1 minute and 60 minutes is an hour and so on. So who decided what a second is?
Well, before we divided time into seconds, we divided time into days and hours. Historians credit the Egyptians with being the first to divide the day into equal parts. While the counting system we’re familiar with is base-10 — you have 10 fingers, after all — the ancient Egyptians had a base-12 system. They counted on their finger joints, using their thumb as a pointer. As a result, they divided the day into 12 parts and the night into 12 parts, which we know from seeing the sundials they left behind. The subdivision of each hour into 60 minutes and each minute into 60 seconds started with the Babylonians, who had a base-60 counting system. (You weren’t going to be counting to 60 using body parts, of course, but that system does have some mathematical advantages I don’t have time to get into.) Anyway, that definition of a second — a 60th of a 60th of a 24th of a day, or one 86 thousandth four-hundredth of the average solar day, which is the time it takes the sun to come back to the same place in the sky — continued to be the standard measure of a second until the 20th century. See, the average solar day actually changes length from year to year, so this definition wasn’t exact enough for science. So in 1900, they were like, ok, instead of making it a fraction of the average solar day, we’ll make it a fraction of the specific solar day on January 1st, 1900. Well, that didn’t really help things — you can’t exactly go back and measure the length of that day. Still, that definition lasted until in 1967 when the second got REALLY specific. Scientists used their knowledge of the atom to define a second as, get ready, nine billion, one hundred ninety-two million, six hundred and thirty-one thousand seven-hundred and seventy periods of the radiation for a Cesium-133 atom. Woof. That sounds way more complicated than counting to 60 on your bodyparts, I know, but scientists can make that measurement anywhere, any time, regardless of the amount of daylight this time of year. And that's key. For ideal precision, a scientist has to be able to check their measurements in the lab, not against some abstract concept like how long the day was in 1900. Thanks for your question, Muhammad! If you have a question, send it into podcast at curiosity dot com.
http://www.abc.net.au/science/articles/2011/11/15/3364432.htm
[NHTSA]
CODY: Today’s episode is paid for by NIT-suh. It can be a little frustrating, especially if you’re in a hurry or running late, to find yourself at a railway crossing, waiting for a train. And if the signals are going and the train’s not even there yet, you can feel a bit tempted to try and sneak across the tracks. Well, don’t. Ever.
ASHLEY: Yeah, trains are often going a lot faster than you expect them to be. And they can’t stop. Even if the engineer hits the brakes right away, it can take a train over a mile to stop. By that time, what used to be your car is just a crushed hunk of metal and what used to be you… well, let’s not even think about that.
CODY: The point is, you can’t know how quickly the train will arrive. The train can’t stop even if it sees you. The result is disaster. If the signals are on, the train is on its way. And you... just need to remember one thing… Stop. Trains can’t.
Here's How You Can Watch the Lyrid Meteor Shower in 2019 — https://curiosity.im/2GcOP3e (Cody)
Meteor shower alert! This Tuesday, keep your eyes to the sky, because it’s that time again for the Lyrids meteor shower. There are a lot of ways that meteor showers can form, but the most common kinds start their lives as passing comets. As a refresher, comets are giant chunks of rock and ice that have been orbiting the sun since the early days of the solar system. As they hurtle through space, they leave debris behind in their tails, and every year the planet Earth passes through chains of comet nuggets. Those chunks then burn up as they enter the atmosphere, creating a beautiful shower of shooting stars. Every April, we smash straight through the path of comet Thatcher, which takes more than 400 Earth years to orbit the sun. And comet Thatcher is where we get the Lyrid meteor showers, which get their name from the fact that they appear to originate from the constellation Lyra. It’s kinda funny that we can see these showers every year, since the comet hasn’t been anywhere near Earth since 1861. Anyway, the Lyrids are going to be at their peak on the morning of this Tuesday, April 23. The best time to see them will be just before dawn, a long time after the moon has set — it'll be a waning gibbous at this point in the month, which will be bright enough to wash out the fainter streaks. Without that additional light in the sky, though, the longer tails of the meteors will be pretty easy to spot just northeast of the bright star Vega. The Lyrids are some of the oldest known meteor showers on record, with sightings dating back about 27-hundred years. So witness a little history this Tuesday morning — it’ll be worth the price of admission, I promise!
ASHLEY: Before we wrap up, we want to give a special shout-out to Dr. Mary Yancy and Muhammad Shifaz, who are executive producers for today’s episode thanks to their generous support on Patreon. Thank you SO. MUCH.
CODY: If you’re listening and you want to support Curiosity Daily, then visit patreon-dot-com-slash-curiosity-dot-com, all spelled out. You can also find a link in today’s show notes.
ASHLEY: Join us again tomorrow for the award-winning Curiosity Daily and learn something new in just a few minutes. I’m [NAME] and I’m [NAME]. Stay curious!