Conversations with Tycho
Every page here is a real conversation, published whole — the question, the answers, the Wikipedia sources Tycho checked before it went up, and the review a few days later. No summaries, nothing rewritten after the fact.
19 October 2026 · with the review
Why does salt melt ice?
Salt does not warm the ice. It lowers the freezing point of the water around it, but only once there is water to dissolve into, and only down to about minus 21 °C.
19 October 2026 · with the review
Why is the ocean salty?
Rivers bring a trace of salt in, the sea floor and its volcanoes add more, and three slow processes take it out again. Why the sea stays salty while the river beside it tastes fresh.
6 October 2026 · with the review
Why do cats purr?
How a cat keeps purring while breathing in and out, why the sound means more than contentment, and why the snow leopard breaks the rule about which cats can purr.
6 October 2026 · with the review
Why does your foot fall asleep?
What is actually happening when a foot goes numb after sitting on it, why the pins and needles come only once you stand up, and how that differs from hitting your funny bone.
3 October 2026 · with the review
What causes brain freeze?
Why ice cream gives you brain freeze: the cold makes the vessels behind your palate clamp down and rebound, and the trigeminal nerve sends the pain to your forehead.
1 October 2026 · with the review
Why is the sky blue, and why is the sunset red?
The same scattering that makes a midday sky blue is what turns it red at sunset. Tycho works through why one mechanism gives two opposite colours.
22 September 2026 · with the review
What happens when you crack your knuckles?
Tycho traces the pop to a cavity forming in the joint fluid, not bursting — and why the same knuckle stays quiet for about twenty minutes afterwards.
22 September 2026 · with the review
Why do onions make you cry?
Cutting an onion sets off a chemistry experiment that ends in a gas your eyes read as an attack. Tycho follows it from the broken cell to the sting.
22 September 2026 · with the review
Why is Venus hotter than Mercury?
Venus is further from the Sun than Mercury and reflects most of the light that reaches it — and is still hotter everywhere, all the time. Tycho works through why, and why Venus cannot undo it.
28 August 2026 · with the review
Why is the Moon moving away from Earth?
The Moon moves about 3.8 cm further from Earth every year. Tycho walks through where the energy comes from — the tides, a bulge dragged ahead of the Moon, and Earth's own spin paying the bill.
Ask your own
These are conversations, not articles — you can have one. No account needed to start, and if you keep it, Tycho comes back in a few days to find out what stuck.
Talk to Tycho