General relativity has made remarkably accurate predictions, and continue to be in accurate in whatever it models.
• Gravitational waves from black holes merging.
• The rate change of Mercury's orbital ellipse orientation.
• The bending of light in gravitational fields.
• The universe’s general expansion (from a hot-dense phase)
•…General Relativity's success is limited in scope.1
The universe (all of space, time, and matter) really did expand from a single hot dense state, whether or not it began as a singularity.
• Galaxies are diverging (“red shifted”) like dots on a balloon.
• A “Cosmic Microwave Background Radiation” permeates space like a gas.
• There is a lot of helium-4, and some deuterium, helium-3, lithium-7.
So? Couldn’t it simply be that…
•…General Relativity’s success is limited in scope.1
General relativity “breaks down” in quantum-sized settings insofar as its predictions may no longer apply; we need a theory of quantum-gravity to unify quantum mechanics and general relativity.
• Quantum influences may rub out predictions of General Relativity
By way of response, however…
• …we ought to give General Relativity's predictions benefit of the doubt.
• …independent lines of evidence for a singular beginning supplement General Relativity's prediction, amplifying the likelihood that it's prediction is accurate.