Scientists find gravity very puzzling. For one thing, they don’t understand 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.
We take so many things for granted. Why do trees grow only so tall and no taller? Why do some potatoes have those mysterious brown holes in them? And why do plants grow right-side up instead of upside-down? Eric Hamilton explores the question.