It is lovely when something is explained in such a way that the ‘light bulb’ goes on inside and one suddenly realises the point of the subject being explained. I teach for a living, but it is still relatively rare that I am sure that such an event has occurred. I often get asked about E=mc2. It is, after all, the most famous equation ever devised. It is easy enough to say that it means that the total energy available from an object is the mass of the object multiplied by the square of the speed of light, but how was such an equation ever worked out? The following video uses a lovely analogy to explain it – and it does so in just under 60 seconds. It may help to have read my previous two blog posts on Relativity – One and Two but you could just dive in and enjoy the beautiful animation and explanation that follows; then revel in the thought that you and its author are related by common descent, and are both members of the most remarkable species ever to have existed on Earth.
OK, so it’s not easy but watch it again and check out the links above. It is a remarkable description of a wonderful bit of thinking. There are more examples of physics animation at Minute Physics on YouTube. I particularly enjoyed “Why there is no fourth dimension” which is so brilliantly explained.
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