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๐Ÿ’ก 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

Why do we scratch our heads when we think?

Why do we scratch our heads when we think? This question came from a reader submission (thanks Adish!). Has a curious question stumped you lately? Feel free to submit your own question here: Submit your question ๐Ÿ““ The short answer We scratch our heads when we think because itโ€™s a form of self-soothing, a way to non-verbally show confusion, and possibly a suppressed primal impulse to attack the question-asker when frustrated. ๐Ÿ“š The long answer Search for a stock photo of someone thinking, and...

butterfly chrysalis

How does a caterpillar change into a butterfly? This question came from a reader submission (thanks Andrea!). Has a curious question stumped you lately? Feel free to submit your own question here: Submit your question ๐Ÿ““ The short answer Caterpillars turn into butterflies by digesting their bodies inside a chrysalis and rebuilding them into butterfly parts by using special cells called imaginal discs. ๐Ÿ“š The long answer If you thought puberty was rough, count your blessings you didn't go...

laser pointers

How do laser pointers work? This question came from a reader submission (thanks Ana for submitting this question on behalf of your German shepherd, Arlo). Has a curious question stumped you lately? Feel free to submit your own question here: Submit your question ๐Ÿ““ The short answer Laser pointers work by exciting atoms so their electrons release light. Mirrors inside the device amplify that light and force the waves to move together in a single direction, creating a narrow, focused beam that...

stainless steel fork and knife on white ceramic plate

What makes you feel full when you're eating? 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 ๐Ÿ““ The short answer Feelings of fullness are triggered when your stomach physically stretches and hormones signal to your brain that youโ€™ve eaten enough. The food's nutritional content, your body fat and gut bacteria, as well as the variety of food on your plate all affect how...

yellowed plastic

Why does plastic turn yellow? ๐Ÿ““ The short answer Plastics typically turn yellow due to photo-oxidation, a process where UV light and oxygen triggers a chain reaction that breaks down the material's chemical bonds. Over time, new molecular arrangements start to absorb more blue and violet light, making the plastic appear yellow. ๐Ÿ“š The long answer Once upon a time, your retro gaming device, lawn chair, or other favorite older plastic object was brilliantly white. Now? It's yellow and brittle....

brown bread with hotdog on top

Why are hot dogs called hot dogs? 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 ๐Ÿ““ The short answer Two main theories explain how hot dogs got their name. The sausages were once called "dachshunds" due to their resemblance to the dog breed, making "hot dog" a natural evolution. Another theory links the name to 19th-century rumors that German sausages contained dog meat. ๐Ÿ“š...

woman in black long sleeve shirt using black laptop computer

Why does your voice sound different on a recording? 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 ๐Ÿ““ The short answer When you speak, you hear yourself through both air and bone conduction, which makes your voice sound deeper. A recording captures only air conduction, losing the lower tonesโ€”so your voice sounds higher and unfamiliar. ๐Ÿ“š The long answer One of the reasons...

flock of white and red rooster on green grass field during daytime

Why can't chickens fly? This question came from a reader submission (thanks, Sonja!). Has a curious question stumped you lately? Feel free to submit your own question here: Submit your question ๐Ÿ““ The short answer Chickens actually can fly, but their body structure and selective breeding limit them to short bursts rather than sustained flight. Certain farming practices also intentionally or unintentionally hamper their flying capabilities. ๐Ÿ“š The long answer Let me stop you right there:...

unknown person lying on brown bench indoors

Why does traveling make you tired? This question came from a reader submission (thanks Renee!). Has a curious question stumped you lately? Feel free to submit your own question here: Submit your question ๐Ÿ““ The short answer Traveling makes you tired because your body is constantly working behind the scenes. Stress keeps your brain on high alert, motion forces your muscles to stabilize, and prolonged sitting reduces circulation. On planes and long car rides, dehydration and lower oxygen levels...

purple butterflies

What causes the "butterflies in your stomach" feeling? This question came from a reader submission (thanks Saurav โค๏ธ). Has a curious question stumped you lately? Feel free to submit your own question here: Submit your question ๐Ÿ““ 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...