Editing Immirzi parameter (section)

==Interpretation==

The parameter may be viewed as a renormalization of [[Newton's constant]]. Various speculative proposals to explain this parameter have been suggested: for example, an argument due to [[Olaf Dreyer]] based on [[quasinormal mode]]s.<ref name="Dreyer2003">{{cite journal |last=Dreyer |first=Olaf |date=2003 |title=Quasinormal Modes, the Area Spectrum, and Black Hole Entropy |journal=Physical Review Letters |volume=90 |issue=8 |pages=081301 |doi=10.1103/PhysRevLett.90.081301 |pmid=12633415 |arxiv=gr-qc/0211076 |bibcode=2003PhRvL..90h1301D|s2cid=206328028 }}</ref>

Another more recent interpretation is that it is the measure of the value of [[Parity (physics)|parity]] violation in quantum gravity,<ref name="Randono2006a">{{cite arXiv |last=Randono |first=Andrew |date=2006 |title=Generalizing the Kodama State I: Construction |eprint=gr-qc/0611073 }}</ref><ref name="Randono2006b">{{cite arXiv |last=Randono |first=Andrew |date=2006 |title=Generalizing the Kodama State II: Properties and Physical Interpretation |eprint=gr-qc/0611074}}</ref> analogous to the theta parameter of QCD, and its positive real value is necessary for the [[Kodama state]] of loop quantum gravity. As of today (2004{{needs update|date=September 2018}}), no alternative calculation of this constant exists. If a second match with experiment or theory (for example, the value of Newton's force at long distance) were found requiring a different value of the Immirzi parameter, it would constitute evidence that loop quantum gravity cannot reproduce the physics of [[general relativity]] at long distances. On the other hand, the Immirzi parameter seems to be the only free parameter of vacuum LQG, and once it is fixed by matching one calculation to an "experimental" result, it could in principle be used to predict other experimental results. Unfortunately, no such alternative calculations have been made so far.