Ole Rømer
1644 – 1710
First to show light travels at a finite speed.
A Danish astronomer, Rømer made the first quantitative demonstration that light travels at a finite speed in 1676, by timing eclipses of Jupiter's moons — a startling result in an age that assumed light was instantaneous.
The frequency-wavelength tools here rest on the finite speed of light Rømer was first to measure. He also reformed the Danish system of weights and measures.
Portrait: a stylized blueprint-line rendering, not a photograph.
Contributions in the toolbox
- 1676
First demonstration that light has a finite speed, from Jupiter's moons.
→ Frequency ⇄ Wavelength