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What's the Big Idea?

Sci-fi writer Arthur C. Clarke once said, "The only way of discovering the limits of the possible is to venture a little way past them to the impossible." Dr. Michio Kaku would like to clarify what kind of impossibility we're talking about.

There's a difference, he says, between ideas that are beyond our technical capabilities today but will be available within the next century, ideas that will be doable 1000 years from now, and ideas that violate the known laws of physics. Surprisingly, very little falls into the third category. 

In this excerpt from his lecture for The Floating University, Dr. Kaku explains that time machines do not violate Einstein's laws of physics, and that – difficult though it might be – future humans would be wise to build one and slip through a wormhole to one of the alternate dimensions proposed by string theory before the cooling universe extinguishes all known life. 

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