Placebo Effect
A sugar pill reliably reduces pain in clinical trials — measurably, not just subjectively. How does a fake treatment produce real healing?
19556 min read
Domain
Biology
Puzzles in fitness, cooperation, cancer, and complexity.
9 entriesFilter these further →
Beginner
Ages 8+, no background needed.
Hawthorne Effect
Workers became more productive every time the researchers changed conditions — even when they changed them back. What was the actual cause?
1924–1932 (studies), 1958 (effect named)6 min read
Intermediate
Curious teenagers and general adult readers.
The Tragedy of the Commons
Every herder gains by putting one more animal on the shared field. The field is destroyed by people behaving reasonably.
196815 min read
Dunbar's Number
You can maintain real relationships with about 150 people. Beyond that, a group becomes something different. Is this a law of human nature?
19927 min read
Flynn Effect
IQ scores rise 3 points per decade worldwide. If the tests measure intelligence, are we smarter? Or is something wrong with the tests?
19847 min read
Moravec's Paradox
A computer beat the world chess champion in 1997. Getting one to pick up a cup it has not seen before is still hard.
198811 min read
Peto's Paradox
A whale has a thousand times more cells than you and lives longer. It should be riddled with cancer. It is not.
1975 (observation), 1977 (Peto's fuller statement)17 min read
The C-value Paradox
An onion carries five times more DNA than you do. A single-celled amoeba carries a hundred times more. Nobody expected that.
1971 (named), 2001 (renamed the C-value enigma)17 min read
Advanced
Undergraduate level in the relevant field.
Levinthal's Paradox
A protein has more possible shapes than the universe has atoms, yet it finds the right one in less than a thousandth of a second.
1968–196917 min read