Plane manufacturers have come up with some interesting ideas. The latest: Turn cabins -- the part of the plane where you sit -- into detachable modules separate from the planes. Then mix and match 'em, and you save all kinds of time and money, Airbus says.
It has been exactly 100 years since Albert Einstein presented his theory of general relativity to an audience of scientists on November 25, 1915. While virtually everyone has heard of Einstein and his theory, very few people have any idea of what the theory actually is.