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The title says it all: this blog features physics videos found everywhere on the web: animations, demonstrations, lectures, documentaries.
Please go here if you want to suggest other nice physics videos, and here if I mistakingly infringed your copyrights. If you understand French, you'll find a huge selection of physics videos in French in my other blog Vidéos de Physique.

Sunday 6 May 2012

Where Does The Sun Get Its Energy?

The sun has been producing light for about five billion years but where does all its energy come from? The most common idea is that the sun is burning gas - like a giant fireball in the sky. If this were true, the sun would have gone out long ago. So how is the sun actually fuelling itself? It is converting its own mass into energy. By combining protons (the nucleus of hydrogen) into helium, it squeezes some mass into energy - 4.3 billion kg per second. It is Einstein's famous E=mc^2 which gives us the quantitative relationship between mass and energy, where c is the speed of light.

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