Clock the Speed of Light
Clocking the Speed of Light
Why is the speed of light important?
-Having a accurate number for the speed of light allows for accurate measurements of the universe around us -Even small inaccuracies make large differences when measuring the space between stars, planets, and galaxies -The more precise our measurement of the speed of light the more precise our measurements are of the universe because light is the universal measurement used
Light as Infinite
-Most scholars agreed that light had an infinite speed until the 17th century. Light having a finite speed was a violation of Aristotelian Mechanics (later replaced by Newtonian mechanics) -There were however some notable dissenters. Aristotle condemned the ideas of Empedocles of Acragas who spoke of light as traveling, but the movement being unobservable to humans. -Around 1000 AD Islamic Scientists Avicenna and Alhazen separately stated that light must have a finite value. Alhazen argued light has a finite speed that differs depending on the medium it travels through.
Historical Measurements of Light
-Light has been measured many ways over the centuries. -As scientific tools have become more complex the accuracy of the measurement of the speed of light has increased
Early Attempts at Measuring the Speed of Light
- Galileo was the first scientist to attempt to determine the speed of light. He did this by placing lanterns a few miles apart and manual covering them and uncovering them. He recognized that his experiment was too simple to accurately measure the speed of light.
- In 1676 Ole Roemer determined the speed of light based on observations of Jupiter’s moons and the relative positions of Jupiter and Earth. He used the commonly accepted value of Earth’s orbit to solve for the speed of light. Unfortunately, he assumed that other stellar bodies did not affect orbital speeds, so his conclusions were incorrect.
18th & 19th Century Attempts
-In 1726 James Bradley, an English Physicist,
Why is the speed of light important?
-Having a accurate number for the speed of light allows for accurate measurements of the universe around us -Even small inaccuracies make large differences when measuring the space between stars, planets, and galaxies -The more precise our measurement of the speed of light the more precise our measurements are of the universe because light is the universal measurement used
Light as Infinite
-Most scholars agreed that light had an infinite speed until the 17th century. Light having a finite speed was a violation of Aristotelian Mechanics (later replaced by Newtonian mechanics) -There were however some notable dissenters. Aristotle condemned the ideas of Empedocles of Acragas who spoke of light as traveling, but the movement being unobservable to humans. -Around 1000 AD Islamic Scientists Avicenna and Alhazen separately stated that light must have a finite value. Alhazen argued light has a finite speed that differs depending on the medium it travels through.
Historical Measurements of Light
-Light has been measured many ways over the centuries. -As scientific tools have become more complex the accuracy of the measurement of the speed of light has increased
Early Attempts at Measuring the Speed of Light
- Galileo was the first scientist to attempt to determine the speed of light. He did this by placing lanterns a few miles apart and manual covering them and uncovering them. He recognized that his experiment was too simple to accurately measure the speed of light.
- In 1676 Ole Roemer determined the speed of light based on observations of Jupiter’s moons and the relative positions of Jupiter and Earth. He used the commonly accepted value of Earth’s orbit to solve for the speed of light. Unfortunately, he assumed that other stellar bodies did not affect orbital speeds, so his conclusions were incorrect.
18th & 19th Century Attempts
-In 1726 James Bradley, an English Physicist,
Cited: (continued) Riddle, Bob. "Star light, star bright." Science Scope Mar. 2009: 82. Academic OneFile. Web. 9 Dec. 2012. Scarborough, Trent and Ben Williamson. “The Speed of Light: Historical Perspective and Experimental Findings.” 9 December 2012 . “Speed of Light.” Youtube.com. 9 December 2012. . “Speed of Light Historical Measurements.” 9 December 2012. . Questions?