Understanding Loneliness

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Thermometers took over a century to agree, and the 37°C norm came from a device that read nearly 2°C high.

Pulse oximeters miss low oxygen about three times as often in Black patients, which delayed some COVID care.

A single loneliness question met basic validity standards in only 19 of 27 EU countries.

Loneliness stems from different gaps for different people, so measures should ask what each person lacks.

When your child has a fever, you reach for a thermometer and trust the number. That trust is newer than it seems. Galileo's early instrument, built around 1600, had no scale at all. It only showed that something had become warmer or colder. Later makers filled their tubes with alcohol, mercury, or air and marked them against different reference points, so two thermometers in the same room could disagree. As the historian Hasok Chang describes in Inventing Temperature, it took well over a century of comparing instruments against one another before readings from different devices meant the same thing.

Even then, errors lasted. In the 1860s the German physician Carl Wunderlich compiled more than a million armpit readings from about 25,000 patients and settled on 37°C as normal body temperature. Medicine used that figure for more than a century. When the physician Philip Mackowiak later tested one of Wunderlich's thermometers, it read almost two degrees higher than modern instruments. The number had outlived the device that produced it.

When the instrument is wrong for some people

Some measurement errors cost more than a decimal point. Pulse oximeters, the clips that read oxygen........

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