Loop quantum gravity
One of the approaches to the problem of Einstein's gravity and its relation to quantum theory is loop quantum gravity. This is a very geometrical approach to reformulating general relativity as a quantum theory. In its structure, it is rather abstract; however, some of its consequences can readily be pictured: In the theory, space turns out to be built of "building blocks" of finite size, and time progresses in "leaps" of finite duration. Mathematically, space is characterized by a "spin network" made of nodes and connections, as can be seen in the image on the left. The film on the following page is an artist's impression of space according to loop quantum gravity - a space of basic geometric building blocks, changing dynamically.