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The podcast where we answer the questions you never knew you had. Produced by Andrew Norton with music by Breakmaster Cylinder, brought to you by Greenpeace.

The podcast where we answer the questions you never knew you had. Produced by Andrew Norton with music by Breakmaster Cylinder, brought to you by Greenpeace.
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The podcast where we answer the questions you never knew you had. Produced by Andrew Norton with music by Breakmaster Cylinder, brought to you by Greenpeace.




An Update & Exciting News!

An update on the podcast and some exciting news. Spoiler - the exciting news is a new podcast. Subscribe Now


Why Do Frozen Lakes and Rivers Sound So Creepy?

Brigitta Green from the perennial winter wonderland of Minnesota has a fitting question for us about ice. After a mysterious, late night howling sound caused “mass slight curiosity” on the streets of St. Paul last winter, she wants to know how it is that a frozen body of water can produce such an eery noise. Chris Polashenski, Arctic researcher and expert on all things cold, has our answer.


What's The Coolest Species Name?

What's the coolest or weirdest official name for a species of plant or animal? And how do they get those funny sounding Latin names anyway?


Why Distinguish Between Fruits and Vegetables?

Is a watermelon a vegetable? Biologically it’s logical, but does the answer depend where you live?


Why Do Animals See Color Differently?

Zookeeper Rick asks why why animals see color differently? Dr. Jay Neitz of the University of Washington Department of Ophthalmology says there is more than one factor that accounts for how animals perceive color. Some plants and animals present vibrant colors we can’t even see and for reasons they don't want us to know.


Do Animals Have Rituals Around Death?

Listener Ross Wintle, driving past a cemetery near his home, wonders if animals other than humans have rituals around death? Barbara J King, professor emerita of anthropology at the College of William and Mary and the author of How Animals Grieve reports that when it comes to animals and death, you’ve gotta look at elephants. However there are also some interesting reports about magpies, red foxes and dolphins showing some interacting with the dead in their groups. Appropriately in a Day of...


Why Do We Laugh At Pain?

Listener Matthew Hollingshead, a skateboard enthusiast, asks why it’s so funny to watch people get hurt. We’re not necessarily talking about critical injuries, more like America’s Funniest Home Videos style failures, pain, and embarrassment. Caleb Warren, an Assistant Professor of Marketing at the University of Arizona helps us answer this question and feel a little better about finding joy in other people’s “hilarious misery”. If you like Completely Optional Knowledge, help support the...


Do Animals Have Eating Contests?

Hilah Johnson hosts a show about cooking (and, naturally, eating)and she came to us with a very on-brand question. Do animals have eating contests? We spoke to biologist Elise Huchard to get the answer. Check out Hilah's cooking show! Find her on Twitter @hilahcooking.


What's Quantum Teleportation?

Listening to Shohini Ghose talk about what would happen if a human reached light speed in Episode 16, Fred Papon of Australia wanted to know more about her research into quantum teleportation. Ghose reveals that teleportation has already happened, but don’t expect someone on the train with you to disappear after saying “Beam me up Scotty.”


How Do Animal Taste Buds Work?

Dallas College professor Patrick Moore, seeing his dog Abbey eating her own poo and swallowing dirty socks, wonders how animal tastebuds work. Danielle Reed, associate director of the Monell Chemical Senses Center, takes a break from feeding her cat Diet Coke to talk about the chemical properties of taste. Both cheese and sweaty socks smell like isovaleric acid. Dogs being omnivores unconstrained by the social cues that govern human behavior are going to go ahead and see if that sock is...


Why Do Siblings Have Rivalries?

Molly and John Knefel, sister and brother co-hosts of the daily podcast “Radio Dispatch” wonder why siblings become rivals. Naomi White, PhD, of Cambridge University, explores the evolutionary and cultural roots of sibling conflict and finds that working things out with your sister or brother teaches important lessons about life and relationships.


What Does the Sun Sound Like? [rerun]

Inspired by freeze-dried ice cream at Space Camp, podcast producer of 99% Invisible Avery Trufelman wonders what the sun really sounds like setting aside the hokey furnace effect shown in movies. Knowing that no sound waves can travel in the vacuum of space, fellow space camper and Completely Optional Knowledge host Andrew Norton finds a marvelous audible version of satellite data from sonification specialist Robert Alexander who trains heliophysicists at NASA’s Goddard Space Flight Center...


Can Music Make You Hungry?

Breakmaster Cylinder, creator of the Completely Optional Knowledge theme music, wonders if music can be used to trigger specific responses in people. Jessica Grahn of the Music and Neuroscience Lab at Western University explores ways that music can influence people and create personal playlists for happier, healthier lives. For host Andrew Norton, a turkey sandwich might be in his future. Listen to Breakmaster Cylinder at and find out more about...


What Is Wind?

Lauren Ober is the host of WAMU's The Big Listen. She wanted to know the answer to a relatively simple question - what is wind? With help from UCLA mathematician Marcus Roper, she got an answer plus something unexpected: the fascinating way mushrooms catch a breeze by making it themselves.


How Do You Take Great Photos From Space?

Jonathan Mehring has photographed all over the world, but there’s one place he hasn’t been yet that he’s dying to learn about: outer space. So we talked to someone who’s spent a whole year in space and taken thousands of photos while he was out there, astronaut Don Pettit. As we learn, even the simplest photography tasks are made difficult when you’re orbiting the Earth in zero gravity. Listen in for Don’s pro-tips on how to capture amazing photos from outer space! Check out Don’s photos...


Are There Lazy Ants?

Have you ever seen an ant just … hanging out? Completely Optional Knowledge listener Bryan Fox hasn’t, and it’s getting under his skin. To get Bryan the scoop on whether ants’ seemingly steadfast work ethic is just a facade, we called up biologist Anna Dornhaus. Anna explains to us how ants have evolved into highly specialized roles that keep their colonies running smoothly, and one of those roles is just … hanging out.


Who Governs Space?

Who makes the rules in outer space? That’s what Completely Optional Knowledge listener Tim Burberich called in to find out. So we got in touch with space lawyer Joanne Irene Gabrynowicz (dream job alert) who walks us through highly political processes and treaties that allow humans to get along in places like the International Space Station. Houston, we have a treaty.


What's the Most Surprising Partnership Between Species?

Emily Schorr Lesnick is the co-host of the SoulGlo podcast, a show about how diversity helps humans thrive. Naturally, she wants to find out if diversity in nature helps animals thrive the same way it helps us. Thinking about unlikely animal partnerships might conjure images of kittens riding turtles, or fish and birds joining forces, but researchers Michele Lanan and Mary Jane Epps bring us some suprising (and actually true) examples of ways life in the wild couldn't continue without what...


Do Invincible Creatures Exist?

Jessica Abel is working on a new book about Mars (Trish Trash: Rollergirl of Mars - available in November 2016) - which got her wondering about the most amazing creatures here on earth. Dr. Roberto Guidetti gives us the lowdown on the incredible and nearly invincible animals he studies. For more on Jessica Abel's upcoming book visit:


What If I Went Light Speed?

Tom Sortodden wants to know what would happen if he went the speed of light. Physicist Shohini Ghose of Wilfrid Laurier University explores the implications of the theory of relativity, abstract art, time and distance and infinite force. Prepare to have your mind blown or a few circuits in your brain shorted.