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Professor Brian Cox explains the concept of entropy and the arrow of time. Entropy is the measure of how many ways in which something can be rearranged. Professor Cox explains that entropy always increases by using a pile of sand as an example. He then explains that the world always tends towards disorder, from order, hence time only goes in one direction.
This clip is from:
Wonders of the Universe
First broadcast:
5 May 2011

Classroom Ideas

This clip is useful for students of Physics or Chemistry. It can help explain why travelling backwards in time is not possible. It is also useful at introducing some interesting and powerful concepts that can help build understanding in many other areas of the curriculum.