Speed of Light | 26 Dec 2024

The speed of light, a fundamental constant in physics, has been determined with increasing precision over centuries.

The speed of light is the rate at which light waves propagate through different materials. In particular, the speed of light in a vacuum is defined as exactly 299,792,458 meters per second.
- Light's speed can vary when it propagates through different materials, depending on the material's refractive index (measure of bending of a light ray when passing from one medium to another).
Early estimates of the speed of light were based on how long it took light to travel a known distance, with measurements improving as instruments advanced.
Ole Roemer (1676) was the first to estimate the speed of light, observing Jupiter’s moons and their varying eclipse timings based on Earth's distance from Jupiter.
- His estimate was 225,300 km/s, which was far from the modern value due to limited knowledge of Jupiter's distance.
Modern measurements of the speed of light are conducted using laser beams and atomic clocks, resulting in the current precise value.