General Relativity Still Holds On Large Scales.

We know general relativity is a great theory, but it hasn't been well tested on "large scales".  Many theories need to be modified on various length scales, so it should not be shocking that it is possible we may need to modify GR for large scales.

However, a recent test, worthy of a Nature Paper, has just been released. It turns out, just as expected, GR passes this large scale test.

General relativity predicts light should bend passing by massive objects. (Like galaxies).  This bending produces lensing effects the analogous to the lens bending light in eye glasses.

The authors describe a parameter, called E_g, that is sensitive to modifications of gravity.  Furthermore, the authors claim this quantity can be measured well without galaxy bias.

This parameter is exactly what we expect from GR.  So, GR has passed yet another test, this time on scales of 10s of Megaparsecs.  Now, this doesn't prove GR 100% true on large scales, but at least for now it is safe.