Template:Are You Sure/January 20

Archimedes used the method of exhaustion to compute the area inside a circle by finding the area of regular polygons with more and more sides. This was an early but informal example of a limit, one of the most basic concepts in mathematical analysis.

• ... that Project SCORE (Signal Communications by Orbiting Relay Equipment) was the world’s first communications satellite, as well as the first successful use of the Atlas rocket as a launch vehicle?

• ... that electrical engineer Elisha Gray invented a harmonic telegraph which transmitted multiple tones simultaneously, and that each tone was controlled by a separate telegraph key?
• ... that physicist David Brewster discovered the photoelastic effect while studying double refraction by compression, inaugurating the field of optical mineralogy?