For 250 years the concept of gravity was so simple: a young Isaac had shown that an apple falls from a tree for the same reason that the Moon orbits the Earth. Then, a young Albert replaced that simple idea with curved “space-time“. Since then, we have had to deal with E=mc^2, parallel universes, and black holes! Gravity plays an important role in the births and deaths of stars, the creation of elements, and even the production of sunlight. In [...]