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and they still can't improve on the edge achived by rubbing a blade on a piece of rock.

A spinning stone wheel doesn't count as a "laser beam" no matter how insistent the salesman is.

You may also notice that it is an inclined plane that's cutting your hair, THE simplest machine...

Actually there's nothing at all "space age" about modern cartridge razors except the price. It's just subtle variations on thousand year old technology. The only real difference is that adding a...