String theory, like quantum theory, is background dependent in that it relies on the existence of time and space. Strings vibrate in space over time and string theory does not describe what time ...

At the time, physicists found themselves facing a crisis: the two most important ideas of 20th century physics, relativity and quantum theory, were known to be fundamentally incompatible.

A novel theory of "wavy space-time" suggests the division between our best descriptions of the universe on its smallest and largest scales may be because gravity does not play by quantum rules.

String theory postulates that there are an additional six dimensions, but they are so tightly curled in the fabric of space-time that they are beyond microscopic – so tiny that the size of one ...

For starters, LQG studies bits of space-time, whereas string theory investigates the behavior of objects within space-time. Specific technical problems separate the fields.

One of the problems of string theory is that five different versions of it exist! Four of these are theories with closed strings, which can be visualised with elastic bands that move in space-time.

The theory failed to unite gravity and quantum mechanics. But it still has become one of the most useful tools in science.

Japanese physicists have created a string theory model that simulates the birth of the universe. In their model, the Big Bang was a "symmetry-breaking event" — a fluctuation that caused three ...