Category Puzzles
A time traveller gives Beethoven’s symphony to Beethoven, who copies it and takes the credit. So who actually composed it? Welcome to the paradox of the thing with no origin.
Two suspects, held apart, each offered the same deal. The maths says both should betray the other, even though silence would serve them both better. The puzzle at the heart of trust.
Give a tortoise a head start and, by one ancient argument, the fastest runner alive can never overtake it. The logic is clean. The conclusion is absurd. Untangling it took 2,000 years.
Replace a ship’s planks one by one until none of the original remains. Is it the same ship? Now rebuild the old planks into a second ship. Which one is the real one?
Measure Britain’s coast with a long ruler and you get one number. Use a shorter ruler and it grows. Keep shrinking the ruler and the coastline heads toward infinity.
A judge promises a prisoner a hanging next week, on a day he will not see coming. The prisoner proves it can never happen. Then it happens, exactly as promised.
A simple coin game has an infinite average payout, so in theory you should stake everything you own to play. Almost no one would pay more than a few coins. That gap founded a science.
In huge collections of real-world numbers, the leading digit is a 1 about 30% of the time, not 11%. The pattern is so reliable that auditors use it to catch fraud.
In 1973 Berkeley seemed to admit men far more often than women. Look department by department and the bias vanishes, even tilts the other way. Same numbers, opposite story.
You have 100 kilograms of potatoes that are 99% water. Leave them out until they are 98% water. They now weigh 50 kilograms. The maths is right, even though it feels impossible.
Someone hands you two envelopes, one holding twice as much money as the other. You pick one. Should you switch? A tempting argument says yes, forever.
A hundred prisoners must each find their own number among a hundred boxes, opening only half. Random guessing gives essentially no hope. One clever rule gives them a 31% chance.
Put 23 strangers in a room and it is a coin flip that two of them share a birthday. It sounds wrong. The maths is stubborn.
In 1990 Marilyn vos Savant gave the right answer to a simple game-show puzzle. Ten thousand readers, a thousand of them with PhDs, wrote in to tell her she was wrong. She wasn’t.
