The Speed of Light

In Our Time: Science

BBC

History

4.5 • 1.4K Ratings

🗓️ 30 November 2006

⏱️ 42 minutes

🔗️ Recording | iTunes | RSS

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Summary

Melvyn Bragg and guests discuss the speed of light. Scientists and thinkers have been fascinated with the speed of light for millennia. Aristotle wrongly contended that the speed of light was infinite, but it was the 17th Century before serious attempts were made to measure its actual velocity – we now know that it’s 186,000 miles per second. Then in 1905 Einstein’s Special Theory of Relativity predicted that nothing can travel faster than the speed of light. This then has dramatic effects on the nature of space and time. It’s been thought the speed of light is a constant in Nature, a kind of cosmic speed limit, now the scientists aren’t so sure. With John Barrow, Professor of Mathematical Sciences and Gresham Professor of Astronomy at Cambridge University; Iwan Morus, Senior Lecturer in the History of Science at The University of Wales, Aberystwyth; Jocelyn Bell Burnell, Visiting Professor of Astrophysics at Oxford University.

Transcript

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0:00.0	Thanks for down learning the In Our Time podcast. For more details about In Our Time and for our terms of use, please go to BBC.co.uk.
0:10.0	I hope you enjoy the programme.
0:12.0	Hello, this week we're discussing the speed of light.
0:15.3	The medium most of you are listening to through radio waves travels at the speed of light.
0:19.8	Those of you closer to the radio transmitter'll hear in our time fractionally before
0:24.1	someone further away. Scientists and philosophers have been fascinated with
0:28.0	a light for millennia. Aristotle wrongly contended at the speed of light was
0:32.0	infinite. It was the 17 of light was infinite.
0:32.8	It was the 17th century before serious attempts were made to measure its actual velocity.
0:37.3	We now know it's about 186,000 miles per second.
0:40.9	Then in 1905, Einstein's special theory of relativity predicted that
0:45.4	nothing can travel faster than the speed of light. This had dramatic effects
0:49.9	on the study of the nature of space and time. It's also been thought that the speed of light is a
0:54.4	constant in nature, a kind of cosmic speed limit, now the scientists aren't so sure.
0:59.2	Joining me to discuss this, John Barrow, Professor of Mathematical Sciences and Gresham Professor of Astronomy at Cambridge University.
1:06.0	Jocelyn Belen-Barnell, visiting Professor of Astrophysics at Oxford University, and Ewen Morris, Senior Lecturer in the history of science at the University of Wales
1:14.4	Abariswith.
1:15.4	John Varro, first of all, what is light?
1:17.2	What's it made of?
1:18.2	Well, it's always a bad question to ask scientists what something is.
1:24.0	We tend not really to know what things really are, but just what they do and what their effects are.
1:30.0	And we look upon light as a way in which energy is transmitted from one place to another
	...

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