Here's what happens when an unstoppable force meets an immovable object

Here's an idea! Let's get reeaaaal pedantic about what it means for an object to be truly "immovable" (i.e. "un-accelerateable") and a force to actually be unstoppable (spoiler: all forces are unstoppable) and use the thought experiment to answer one of the oldest, most ancient questions to ever come up ever. Turns… »1/25/13 3:20pm1/25/13 3:20pm

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… »9/06/11 11:00am9/06/11 11:00am