Astronomy Picture of the Day . Quantum Gravity Claimed Detected on Earth . ... NPAC Explanation: Does gravity come in chucks? A theory known as Quantum Mechanics tells us about how the universe works on the smallest scales, while Einstein 's General Theory of Relativity tells us about how gravity and the universe works on the largest scales. ... Publications with keywords: quantum mechanics - gravity - string theory . Publications with words: quantum mechanics - gravity - string theory . ...