Loop quantum gravity (LQG) is a theory of quantum gravity that tries to combine general relativity (gravity) and quantum mechanics by showing that space itself is made of tiny, discrete loops.
Instead of space-time being smooth and continuous, LQG says it is made of tiny loops, like a woven fabric. These loops are at the Planck scale (~10⁻³⁵ m) and are regarded as the quantums of reality. Networks of loops are called spin networks which give rise to spin foam, which is like the quantum foam.
General relativity and quantum mechanics contradict each other when trying to explain black holes or the Big Bang.
LQG predicts:[]
- No singularities – Black hole centers and the Big Bang are not infinite points but ultra-dense "quantum regions."
- Planck stars – a quantum alternative to singularities inside black holes.
- Space and time emerge from quantum loops.
- Big Bounce – Instead of a singular Big Bang, the universe might have "bounced" from a previous collapsing universe.
LQG is an alternative to string theory.