You might think you have gravity pretty well figured out. If you drop a ball out of a window, a short time later it will hit the ground. The higher up you drop it, the faster it travels before it hits the ground. But something far more profound is going on, and it’s nicelyillustrated by the image you see above. Albert Einstein published his theory of general relativity back in 1915, and it’s now the agreed-upon math that describes gravity.