How Einstein Came Up With Special Relativity

Time dilation. Length contraction. The fact that time moves faster at your face than it does at your feet. These are all experimentally verified consequences of the Special Theory of Relativity, proposed in 1905 by Albert Einstein. But the theory also helped explain one of the most nagging questions of modern physics, … » 3/19/12 8:20am 3/19/12 8:20am

How do we know for sure that we live in three dimensions?

Sure, our surroundings certainly appear to exist in three dimensions, but any good Cartesian will tell you that the appearance of a material object alone is insufficient evidence of its true nature. So how do we go about proving that we aren't, in fact, deluded inhabitants of Abott's two-dimensional Flatland, or even … » 9/06/11 8:00am 9/06/11 8:00am