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Bending Spacetime in the Basement (1997)

Bending Spacetime in the Basement

This is small, but it is an object visible to the naked eye (easily with a modest magnifier), and heavy enough to fall under the influence of Earth's gravity, as opposed to smaller and lighter particles of dust and smoke which stay suspended in the air for long periods of time. Around 250 B.C., by measuring the difference in the angle of sunlight at noon on the June Solstice, which illuminated the bottom of a well at Syene (now Aswan) Egypt near the Tropic of Cancer, with the length of the shadow cast on the same date and time by a vertical pillar in Alexandria, a known distance to the North, Eratosthenes determined the Earth's circumference. test masses would be preferable, but to show how robust this experiment is I opted for a couple of rocks—two kilogram paving stones like those which border every highway in Switzerland, where roads are so built to last that Julius Cæsar would shake his head in admiration.

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