Think about it: the answer to the question "Is it opposite day?" will always be no. It's a head-scratcher. So how do you figure out if it is, in fact, opposite day? We talk to two philosophers who walk us through how questions like these can bend and twist the truth  -- and our minds. We learn about the sinister-sounding "Liar Paradox." And we find out that it's not only our brains that use logic, it's used by the machines all around us too. Plus: A brand new mystery sound and an answer to the question: How do erasers erase?

'Is it opposite day?' and other mind-bending paradoxes

Brains On!® is a science podcast for curious kids and adults from American Public Media. Each week, a different kid co-host joins Molly Bloom to find answers to fascinating questions about the world sent in by listeners. Like, do dogs know they’re dogs? Or, why do feet stink? Plus, we have mystery sounds for you to guess, songs for you to dance to, and lots of facts -- all checked by experts.

Kids & Family

Education for Kids

Have you ever taken a big ol’ whiff of rotten milk? It probably smelled like dirty socks or stinky garbage. Blech! But why does food go bad, and how can we be sure that something is fresh and safe to eat?
Join Molly and co-host Rachel as they explore the world of food expiration dates — those little numbers and dates on food packages that help us figure out how old food is! Together, they’ll find out why food goes bad, listen to a rotten egg sing about the power of the sniff test, and learn about the history of expiration dates from Forever Ago host Joy Dolo! All that plus a treat for your ears — an all-new mystery sound!
Subscribe to Smarty Pass for ad-free feeds, bonus episodes, and ticket discounts!
Today’s episode is sponsored by:
- Sitkaseafoodmarket.com - Use promo code Molly35 to receive $35 off your first order.
- Indeed.com/brainson - Receive a $75 sponsored job credit with code brainson
- Poshpeanut.com/brainson - Receive 20% off your first order

How can you tell when food is expired?

Ouch! If you’ve ever stubbed your toe, gotten a paper cut or fallen off your bike, you know that getting hurt is no fun. Sometimes we can take medicine to help feel better, like ibuprofen. But how does that medicine know where to go in our bodies to stop the pain? 

In this episode, Molly and kid co-host Skylar explore where pain comes from and chat with expert Dr. Amanda C de C Williams about why it’s useful. Then they’ll eavesdrop on an ibuprofen pill on its first day of work to find out how it does its job. And of course, an all new mystery sound!
Subscribe to Smarty Pass for ad-free feeds, bonus episodes, and ticket discounts!
Today’s episode is sponsored by:
- Sitkaseafoodmarket.com - Use promo code Molly35 to receive $35 off your first order.
- Indeed.com/brainson - Receive a $75 sponsored job credit with code brainson

How does ibuprofen help stop pain?

Oh no! It looks like Brains On host Molly Bloom and producer Marc Sanchez are in some deep trouble, and the only way to get out of it is with an extra special game of Mystery Sound. Will either of them be able to guess the right sound? Grab your Smarty Pass to find out!

Smarty Pass Sneak Peek: Mystery Sound Investigation

On April 8, a total solar eclipse will be visible on a path that crosses North America, from the west coast of Mexico to the east coast of Canada. In this episode, Molly and co-host Aminah cover all your eclipse essentials: What causes an eclipse? What’s it like to experience one? How do you watch one safely? (Spoiler alert: Don’t stare at the sun without special eyewear. Really. Please. Don’t do it.) Plus, indigenous science educator Nancy Maryboy tells us about Navajo and Cherokee traditions during an eclipse and we’ll meet Dr. Ralph Chou, a scientist who has seen 29 total solar eclipses. And, of course, a stellar new mystery sound!
Come see Brains On live in Washington, DC, Princeton, NJ, and Brooklyn, NY! Get tickets here: brainson.org/events
Subscribe to Smarty Pass for ad-free feeds, bonus episodes, and ticket discounts!
Today’s episode is sponsored by:
- Sitkaseafoodmarket.com - Use promo code Molly35 to receive $35 off your first order.
- Indeed.com/brainson - Receive a $75 sponsored job credit with code brainson

Everything you need to know before the 2024 solar eclipse

We love a good mystery, and UFOs are magnificently mysterious! But are they real? In this episode, Marc and Sanden take over the Brains On feed with a new episode of their radio show, Hoax Hunters. They’ll look into the myths and hoaxes surrounding UFOs (which stands for unidentified flying objects). Plus, they’ll talk about what kinds of things often get mistaken for UFOs and how you can stay smart and skeptical when hearing shocking information. And of course, an episode about mystery will have an all-new Mystery Sound!
Read more about Val Johnson from MPR News.
And if you love Hoax Hunters, check out our Making Sense of Myths series!

Bigfoot, Unicorns and Dragons
Lost Cities
Mermaids, Kraken and the Loch Ness Monster
Aliens and UFOs



Come see Brains On live in Washington, DC, Princeton, NJ, and Brooklyn, NY! Get tickets here: brainson.org/events
Subscribe to Smarty Pass for ad-free feeds, bonus episodes, and ticket discounts!
Today’s episode is sponsored by:
- Sitkaseafoodmarket.com - Use promo code Molly35 to receive $35 off your first order.
- Indeed.com/brainson - Receive a $75 sponsored job credit with code brainson

'Is it opposite day?' and other mind-bending paradoxes

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