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πŸ’‘ Today You Should Know

Learn something new every Friday. Join 2,000+ nerds and satisfy your curiosity one question at a time with topics including science, technology, history, and more.

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Featured Post

What causes the "butterflies in your stomach" feeling?

What causes the "butterflies in your stomach" feeling? This question came from a reader submission (thanks Saurav ❀️). Has a curious question stumped you lately? Feel free to submit your own question here: Submit your question πŸ““ The short answer The "butterflies in your stomach" feeling happens when your brain activates the fight-or-flight response, releasing adrenaline and redirecting blood away from your digestive system. This reduces oxygen flow to the stomach, causing a fluttery...

person with band aid on middle finger

Why do paper cuts hurt so much? 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 πŸ““ The short answer Paper cuts hurt so much because they cause jagged wounds, hit densely packed nerve endings in your fingertips, and are shallow enough to stay exposed without quick healing. πŸ“š The long answer While much of our daily lives has gone digital, we're still at risk of getting the...

brown and white border collie mix

How does the birthday paradox work? πŸ““ The short answer The birthday paradox shows that in a group of 23 people, there’s over a 50% chance of a shared birthday. Only 23 people seems counterintuitively low, but with 253 possible pairings, a match becomes far more likely than it seems at first glance. πŸ“š The long answer How many people must be in a group for there to be a greater than 50% chance that two share a birthday? The answer? Just 23 people. Fill the room with 75 people and the likelihood...

super glue

How does superglue work? πŸ““ The short answer Unlike water-based glues that bond through evaporation, superglue works because of a chemical reaction triggered by the tiny amounts of moisture in the air. Its cyanoacrylate molecules rapidly link together into a strong, plastic-like material that bonds surfaces almost instantly. πŸ“š The long answer Superglue? More like super-duper-glue. A one square-inch bond using superglue can hold more than a ton of weight. In fact, the Guinness World Record tops...

woman in gray sweater carrying girl in blue denim jacket

Why are people ticklish? This question came from a reader submission (thanks to both Aastha and an anonymous reader!). Has a curious question stumped you lately? Feel free to submit your own question here: Submit your question πŸ““ The short answer When someone touches ticklish spots, your skin sends signals to your brain, triggering reflexes like squirming and laughter. Ticklishness likely evolved to protect sensitive areas of the body and to promote social bonding. πŸ“š The long answer When you...

white cloud on sky

How do clouds float? This question came from a reader submission (thanks Vinay!). Has a curious question stumped you lately? Feel free to submit your own question here: Submit your question πŸ““ The short answer Clouds stay up in the sky because their tiny water droplets fall so slowly that rising air can blow them back up. Additionally, clouds' moist air is lighter and more buoyant than dry air, and heat released during condensation helps keep them aloft. πŸ“š The long answer Cloud watching is a...

camellia in snow

Why do some flowers bloom in the winter? This question came from a reader submission (thanks Aunt Kathy!). Has a curious question stumped you lately? Feel free to submit your own question here: Submit your question πŸ““ The short answer Winter-blooming plants evolved to take advantage of the limited competition for pollinators, light, and soil resources. Additionally, some wind pollinators benefit from the leafless winter canopy, allowing their pollen to travel more freely. πŸ“š The long answer...

champagne popping

Why is New Year's Day on January 1? This question came from a reader submission (thanks Aastha!). Has a curious question stumped you lately? Feel free to submit your own question here: Submit your question πŸ““ The short answer January 1 became New Year's Day in 45 BCE when Julius Caesar reformed the Roman calendar, aligning it with the start of Roman consuls’ terms. Pope Gregory XIII later cemented this date in 1582 with the Gregorian calendar, now used worldwide. πŸ“š The long answer New year,...

man carrying barbell at the gym

Why do you feel sore the day after a workout? 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 πŸ““ The short answer Delayed onset muscle soreness is caused by tiny tears in your muscle fibers when you work out. During the repair process, inflammation increases the sensitivity of surrounding nerve endings, which triggers a sensation of pain. It's possible this adaptation...

a train station with a clock on top of it

Why are there so many Union Stations in America? This question came from a reader submission (thanks Natalie!). Has a curious question stumped you lately? Feel free to submit your own question here: Submit your question πŸ““ The short answer Many train stations in the United States are named Union Station because it was common for private railroad companies to collaborate on building a single shared terminal within a city in an effort to save money and make train travel more convenient for...