We have done nothing to change course, despite the rapid rate at which we are exhausting the Earth's resources. In a recent TED talk, Australian Paul Guilding tells us that it is beyond dispute, beyond any margin of error, that "the Earth is full." To sustain current human activity, we'd need 1.5 Earths. Therefore, we are at the "end of growth," and Guilding says it's well underway. The evidence is all around us. So how are we going to respond and react to this crisis? And now for an opposing point of view, also at TED: Peter Diamandis makes a case for optimism -- that we'll invent, innovate and create ways to solve the challenges that loom over us. "I’m not saying we don’t have our set of problems; we surely do. But ultimately, we knock them down.” OK, so one expert says we're in massive trouble and the other says things have never been better. No wonder people are so suspicious about experts.