If you had less than one second to make a life-or-death decision to shoot a man who might be armed with a lethal weapon, what would you do? Would the ethnicity of the man affect your decision?

Could science ever make the clock move backwards? Experiments in quantum physics are showing that the future influences the present: what happens later limits the choices we think we have now.

Evolution say that all life exists only to reproduce; a new theory proposes that instead of passing on genes, humans have another purpose.

Our universe seems real. But what if it's a video game? Scientists in a variety of fields are taking seriously the possibility that we live in a virtual reality.

We all agree lying is shameful. Yet we still deliberately deceive each other constantly. Are our brains wired for lying from a young age? The brains of pathological liars may provide insights. Will technology make it easier for us to be dishonest, or could it someday instantly reveal someone is lying? Perhaps we are deceitful because our limited senses prevent us from seeing the real truth. Scientists say our own memories deceive us, and have managed to implant false memories. Other scientists look for ultimate truth in the subatomic world - only to end up turning reality on its head.