Scientists have known for a long time that this is an incomplete theory though. (businessinsider.com)
If such a «hidden variables theory» is true, QM must be an incomplete theory. (faith.org.uk)
But in the 1960s, the American physicist Robert H. Dicke of Princeton, who died in 1997, noted that if the interior of the sun were rotating rapidly — compared to a slower speed observed at the surface — then the non-spherical component of the sun's gravitational field could produce up to 10 percent of the effect Einstein had computed, in which case, General Relativity would be an incomplete theory of gravity. (scientificamerican.com)