I have heard the following criticism from a well-known high-energy physicist: “Loop gravity is certainly
physically wrong because it is not supersymmetric, and because it is in four dimensions”. This is silly. For the
moment the world still insists on looking four-dimensional and non-supersymmetric in all experiments. Science
is to adapt our ideas to what we find in Nature; it is not to disbelieve Nature because we like our ideas. We
must not mistake very interesting hypotheses (such as supersymmetry and higher dimensions) for established
truths.