Is reality an ethereal, mathematical poem... or is it made up of solid, physical stuff? In this short, we kick rocks, slap tables, and argue about the nature of the universe with Jim Holt.

It's comforting to think that if you take an object -- a rock, let's say -- and break it down into tinier and tinier more elemental parts, that that's exactly what you end up with: smaller and smaller particles until you reach the smallest. And voila! Those are the building blocks of everything around us.

But as Jim Holt, author of Why Does the World Exist? points out... that's an old worldview that no longer jives with modern-day science. If you start slicing and sleuthing in subatomic particle land -- trying to get to the bottom of what makes matter -- you mostly find empty space. Your hand, your chair, the floor...it's all made up of mostly of nothing. So what makes it all take shape?

Robert and Jim go toe-to-toe for a friendly dust-up over whether, at its very base, the universe is made up of solid bits and pieces of stuff...or a cloudy foundation that, more than anything else we can put our fingers on, resembles thoughts and ideas.