Time is a loop

Loop quantum gravity

Loop quantum gravity or loop quantum gravity is the German term that is occasionally used for loop quantum gravity (LQG).

Which loops are meant?

The LQG is a quantum gravity in which the researchers tried directly to link the concepts of quantum theory (more precisely: quantum mechanics) and general relativity (ART). Goal: The quantization of space-time. The resulting space-time quanta become Wilson loops or short Loops (German grind) called.

Quanta of spacetime: loops

The loops are loop-shaped structures that build up the Hilbert space of the LQG. Their interaction and their suggestions create space-time. This spacetime is no longer smooth and continuous, as in Einstein's ART, but is quantized on the Planck scale. Instead of loops, theSpin networks found as an alternative and mathematically more favorable orthonormal basis.

Quanta of spacetime: loops

The loops are, however hypothetical quantathat have not yet been observed in nature or for which there are indirect indications. However, loop quantum gravity offers some interesting aspects that are currently being tested experimentally as well as being further developed in theory.
Another theory also strives for a quantization of spacetime: the string theories or the M-theory. Here the quanta of gravity are the gravitons. In the future, the physical experiments will hopefully make one of the two theories a favorite or bring completely new insights to light in order to renew the view of nature.

additional Information

A comprehensive presentation of the theory of loop quantum gravity can be found under the entry loop quantum gravity.