Speed of light timeline

Galileo Galilei

Feb 15, 1564

-February 15, 1564- January 8, 1642
-Born in Piza, Italy
-Attended University of Piza
-Had 2 daughters and 1 son with Marina Gambina
-He's often called the "Father of Modern Science" for his many contributions to several fields of science (physics, astronomy, cosmology, mathematics, and philosophy).

Christaan Huygens

Apr 14, 1629

-April 14, 1629 -July 8, 1695
-Born in The Hogue, Netherlands
-Attended orange College of Breda and Leiden University
-Best known for his wave theory of light

Galileo's Experiment

1632

Galileo made an attempt to find the speed of light but was unable to perform an accurate experiment. He and an assistant stood on top of hills 1 mile apart. They each had a lantern and the plan was for Galileo to open his lanterns shutter and then his assistant would open his shutter when he saw the light, and then Galileo would time how long it took for him to see his assistants light. His results were inconclusive.

Ole Roemer

Sep 25, 1644

-September 25, 1644 -September 19, 1710
-born in Aarhus, Denmark
-Married Anne Marie Bartholin
-Attended Copenhagen University
-Best known for being the first person to calculate the speed of light, and prove that the speed of light is finite

Roemer's Experiment

1676

Roemer measured the speed of light by timing the eclipses of Jupiter's moon Lo. He observed a discrepancy between the timing of Lo's eclipses. Over half a year, Lo had 102 eclipses with a maximum delay of 16.5 minutes. He used this information as well as the Earth’s diameter to calculate that the speed of light was 214,000 km/s. This value is incorrect because the measurement of Earth’s diameter was incorrect at the time and because there was a mistake in the measurement of the delay.

Huygen's Experiment

1678

Huygens based his calculations on Roemer's estimate that light traveled around the Earth in 22 minutes (it takes 17 minutes to go around the earth). Huygens estimated that the Earth's diameter was 12,750 km and the diameter of Earth's orbit was 24,000 earth diameters. With these measurements, he estimated that the speed of light was about 212,400 km/s. Because Roemer's estimate was wrong and Huygens's calculations had mistakes, his estimate of the speed of light is wrong.

Jean Foucault

Sep 18, 1819

-September 18, 1819- February 11, 1868
-Born in Paris France
-Best known for the “Foucault pendulum” which demonstrated the effects of the earth’s rotation
-Performed many experiments with fellow scientist Armand Fizeau
-He improved Fizeau’s speed of light experiment for a slightly more accurate measurement

Armand Fizeau

Sep 23, 1819

-September 23, 1819- September 18, 1896
-Born in Paris, France
-Best known for early measurements of the speed of light
-Attended Paris medical school and College Stanislas de Paris
- Married Therese Valentine de Jussieu and had 2 daughters and 1 son
-Preformed many experiments with fellow scientist Jean Foucault

Fizeau's Experiment

1849

Fizeau's experiment consisted of a light source, a cogwheel, and a mirror which was placed 8km from the cogwheel. He suggested that the amount of time it took the cogwheel to move the width of 1 cog was the same as the amount of time it took the light beam to travel to the mirror and back and be blocked by the adjacent cogwheel tooth. He was able to calculate speed of light fairly accurately with his experiment. He found the speed of light to be 313, 300 km/s.

Albert Michelson

Dec 19, 1852

-December 19, 1852 -May 9, 1931
-Born in Strzelno, Poland
-Married Margaret Heminway and then Edna Stanton
-Had 4 daughters and 2 sons
-Attended United States Naval Academy, Cave West Reserve University, Humboldt University of Berlin, and Heidelberg University
-Best known for his measurement of the speed of light

Foucault's Experiment

1862

Foucault’s experiment is an improved version of Fizeau’s apparatus. He replaced the cogwheel with a rotating mirror and was able to find a more accurate speed of light, 289,000 km/s. He also found that light was slower in water than it was in air by inserting a tube full of water between the rotating mirror and the distant mirror.

Michelson's Experiment

1879

Michelson’s experiment consisted of a half-transparent mirror at a 45-degree angle which split a beam of light in half sending them in a perpendicular path. Those beams of light were bounced back to the half-transparent mirror which split the returning beams in half again. Half of each of the returning beams went the same direction and their interference patterns were able to be observed. Through this experiment, he was able to calculate the speed of light was 299, 853 km/s.