What happens to the temperature of the atmosphere the higher you go? This question came from a reader submission (thanks Omar!). Has a curious question stumped you lately? Feel free to submit your own question here: Submit your question π The short answer The higher you go in the atmosphere, the temperature either rises or falls depending on the layer. These changes are caused by how different parts of the atmosphere absorb energy from the Sun and how air pressure affects heat. π The long...
11 days agoΒ β’Β 7 min read
Why do men have nipples if they can't breastfeed? This question came from a reader submission (thanks Pedro's daughter!). Has a curious question stumped you lately? Feel free to submit your own question here: Submit your question π The short answer Men have nipples because all embryos start developing the same way, and nipples form before sex-specific genes activate. They likely remain simply because thereβs no evolutionary pressure to remove a harmless trait. π The long answer Great thinkers...
26 days agoΒ β’Β 4 min read
Do sports teams that train in high altitudes have a home advantage? This question came from a reader submission (thanks Jacqui!). Has a curious question stumped you lately? Feel free to submit your own question here: Submit your question π The short answer There is strong statistical evidence that high-altitude teams have a home advantage, largely because visiting players experience reduced oxygen intake and quicker fatigue at elevation. π The long answer It's high time we level up our...
about 1 month agoΒ β’Β 7 min read
How was bread invented? This question came from a reader submission (thanks Rodrigo!). Has a curious question stumped you lately? Feel free to submit your own question here: Submit your question π The short answer Bread originated over 14,000 years ago with early humans baking ground wild grains on hot stones. Over time, developments in agriculture, fermentation, and oven construction led to increasingly specialized and widespread bread production across ancient civilizations. This week's...
about 1 month agoΒ β’Β 7 min read
Why does your stomach growl? This question came from a reader submission (thanks Cory!). Has a curious question stumped you lately? Feel free to submit your own question here: Submit your question π The short answer Stomach growling is caused by muscle contractions that move food, liquid, and gas through your digestive system. These sounds are amplified when your stomach is empty but also occur during digestion after a meal. This week's newsletter is sponsored by 1440, a free daily U.S. news...
about 2 months agoΒ β’Β 5 min read
Longtime readers of Today You Should Know may recognize this question β it's a repeat! My dad and I are currently on a much-anticipated, multi-day bike trip. Unfortunately I didn't manage to crank out a new newsletter before cranking on my pedals, so I hope you enjoy (re)learning the physics of biking. I sure am enjoying them right now. All my best, π π΄βοΈ Caitlin Why is it easier to balance on a moving bike? This question came from a reader submission (thanks Dad!). Has a curious question...
about 2 months agoΒ β’Β 5 min read
Where does trash go? This question came from a reader submission (thanks Zuzu!). Has a curious question stumped you lately? Feel free to submit your own question here: Submit your question π The short answer Trash typically goes through a multi-phase journey: it's first collected and sorted, then processed at various facilities depending on its type. Most waste ends up in landfills, but some is recycled, composted, incinerated for energy, or even exported. Last week, I asked how you'd feel if...
2 months agoΒ β’Β 9 min read
How does Today You Should Know work? This question came from no one in particular, but seeing as this is the 150th edition of the newsletter, I thought I'd do a behind-the-scenes. I could not come up with all these newsletter topics on my own, so please keep the curious questions coming! Submit your question π The short answer Fueled by reader-submitted questions, I work on Today You Should Know nearly every morning β researching, creating custom diagrams, writing, editing, and managing the...
2 months agoΒ β’Β 9 min read
How do controlled burns work? This question came from a reader submission (thanks Mom!). Has a curious question stumped you lately? Feel free to submit your own question here: Submit your question π The short answer Controlled burns, or prescribed fires, are intentionally set by professionals to reduce wildfire risk and support ecosystem health. Burn bosses must get a rigorous burn plan approved and execute with carefully designed ignition methods and timing to control fire behavior. π The...
2 months agoΒ β’Β 6 min read