Type

Measurement

The act of quantifying changing what is quantified.

20 entriesFilter these further →

Beginner

Ages 8+, no background needed.

Computer ScienceLawFamousBeginner

Moore's Law

A pattern that held for fifty years: every two years, computers got twice as powerful for the same price. What happens when it stops?

19657 min read

EconomicsPrincipleFamousBeginner

Pareto Principle

80% of results come from 20% of effort. 80% of bugs from 20% of code. Is this a law of nature, or a coincidence with a catchy ratio?

18966 min read

PsychologyLawFamousBeginner

Parkinson's Law

Give yourself a week for a task that takes an hour, and it will take a week. Why does work expand to fill available time?

19556 min read

PsychologyEffectFamousBeginner

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

PsychologyEffectBeginner

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

MathematicsBeginner

The Coastline Paradox

How long is the coastline of Britain? The answer depends on how you measure it. As the ruler gets shorter, the answer grows without bound.

1951 (Richardson), 1967 (Mandelbrot)7 min read

Intermediate

Curious teenagers and general adult readers.

EconomicsFamousIntermediate

Goodhart's Law

The moment you measure something and start rewarding the number, the number stops telling you what it used to.

1975 (Goodhart's formulation), 1997 (Strathern's phrasing)14 min read

PhysicsFamousIntermediate

Schrödinger's Cat

A cat sealed in a box, neither alive nor dead until somebody looks. The story was invented to show the idea was absurd.

193514 min read

MathematicsLawIntermediate

Benford's Law

Look at the first digit of every number in a newspaper. You'll see 1 far more often than 9 — and it is a mathematical law, not a coincidence.

19388 min read

PsychologyEffectIntermediate

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

MathematicsIntermediate

Gabriel's Horn

A shape you can fill with a finite bucket of paint but whose inside you could never finish painting. How?

16417 min read

PhysicsIntermediate

The Mpemba Effect

A pot of boiling water and a pot of cold water go into the same freezer. Which freezes first?

1963 (observed), 1969 (published)8 min read

MathematicsLawIntermediate

Zipf's Law

The most common English word is twice as frequent as the second. Why does language obey the same mathematical law as city populations?

19357 min read

BiologyIntermediate

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

EconomicsIntermediate

The Easterlin Paradox

Richer people are happier than poorer people. Yet a whole country getting richer does not seem to get happier.

197423 min read

Advanced

Undergraduate level in the relevant field.

PhysicsFamousAdvanced

Maxwell's Demon

A tiny creature sorting fast molecules from slow ones appears to make heat flow the wrong way, for free, forever.

1867 (letter to Tait), 1871 (published in Theory of Heat)18 min read

PhysicsAdvanced

The Ladder Paradox

A ladder too long to fit inside a barn fits inside it — and also does not — depending entirely on who is watching.

1905 (the physics), 1961 (first prominent published version)19 min read

EconomicsAdvanced

The Productivity Paradox

Computers arrived in every office through the 1970s and 80s. Measured productivity did not move for two decades.

1987 (Solow's remark), debate ongoing17 min read

Expert

Graduate level or specialist readers.

PhysicsExpert

The Black Hole Information Paradox

Physics insists information can never be destroyed. Black holes appear to destroy it. Both of those cannot be true.

1974/75 (Hawking radiation), 1976 (the paradox stated)24 min read

PhysicsExpert

The EPR Paradox

Measure one particle here and you instantly know something about its partner light-years away. Einstein thought this proved physics was unfinished.

1935 (argument), 1964 (Bell's theorem), 2015 (loophole-free tests)21 min read

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