Lately it’s been fashionable to say that hunter-gatherers lived better than we do. They had more free time, they followed more natural sleep cycles, and so on. But is our picture of hunter-gatherer society right? A giant earth mound in Louisiana suggests we know less than we think. Anthropologist Tristram R. Kidder explains.
Scientists find gravity very puzzling. For one thing, they don’t understand is why it is so weak; that is, why it takes so much stuff (like a planet’s worth) to generate much gravitational force. Perhaps, they say, it is leaking out of our universe. Physicist Adam Archibald explains how this could be and describes an experiment to detect leaks.