Author: John F. Lindner

Wires suspended above our streets are a late 19th century technology stubbornly persisting into the 21st century. They can hum in a breeze. A wire disturbs the air flow by shedding eddies alternately up and down, sometimes fast enough to be heard as a musical note. The wire’s vibration can enhance the sound’s volume and persistence. The animation above…

The escapement is one of history’s greatest inventions; it enables a collection of wood or metal to tell time. The animation below illustrates a pendulum clock’s deadbeat escapement, apparently introduced by Richard Townseley, Thomas Tompion, and George Graham in the late 1600s and early 1700s. The escapement wheel transfers energy to the pendulum to overcome…

This month is the 100th anniversary of Albert Einstein’s November 1915 discovery of the gravitational field equations of General Relativity, in which test masses move along the straightest possible paths (called geodesics) in spacetime curved by the density and flux of energy and momentum (including mass and pressure). General Relativity allows spacetime to be topologically…