Emergence of string-like physics from Lorentz invariance in loop quantum gravity

Understand

We consider a quantum field theory on a spherically symmetric quantum space time described by loop quantum gravity.

• The spin network description of space time in such a theory leads to equations for the quantum field that are discrete.
• We show that to avoid significant violations of Lorentz invariance one needs to consider specific non-local interactions in the quantum field theory similar to those that appear in string theory.
• This is the first sign that loop quantum gravity places restrictions on the type of matter considered, and points to a connection with string theory physics.