Hi, GR explains the perihelion precession of Mercury, the deflection of light and the gravitational redshift pretty accurately. However, predictions for larger scales seem to be quite wrong, and physicists introduce stuff like the cosmological constant, dark matter and energy. Why are they still so sure that GR is correct and hence dark matter and energy must exist? Why is this more likely than GR being wrong and having to be replaced by a theory that doesn't need such inelegant corrections like dark matter and energy? I'm a bit surprised that GR is celebrated as being incredibly successful while its predictions are just so wrong on cosmological scales so far.