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GPS satellites carry clocks that would drift, relative to clocks on the ground, if engineers ignored relativity. Special relativity and general relativity pull those clocks in opposite directions, and the general effect wins. Without a correction, the position your phone shows would wander by kilometers a day. The map in your pocket is a physics experiment that has to stay honest.

Satellite navigation only works because the clocks are corrected for relativity.

Relativity in the Global Positioning System · Neil Ashby, Living Reviews in Relativity · 2003 · Factapp

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The first website is still at info.cern.ch. Tim Berners-Lee put it up at CERN in 1991 to explain the World Wide Web project itself: a way to follow links between documents on different computers. The page is plain text and a few links. Everything noisier on the web is a descendant of that small, serious note.

The web began as a page about how to link pages, and that page is still there.

The birth of the Web · CERN · 1991 · Factapp

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Ada Lovelace, writing notes on Charles Babbage's Analytical Engine, saw that a machine which handled symbols could do more than arithmetic. A note could stand for a note of music, or a letter, if the machine followed rules. She was describing software before there was a computer to run it. The insight was about symbols, not about gears.

Lovelace's leap was that a machine of symbols could compose more than sums.

Ada Lovelace · Encyclopaedia Britannica · 1843 · Factapp

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