If we celebrate provocative new experimental findings, we should also celebrate the careful null results (experiments that agree with existing theories) on which much of science is based. Back in October we pointed to a new analysis that used observations of gravitational lensing by large-scale structure to test Einstein’s general relativity on cosmological scales, with the intriguing result that it didn’t seem to fit. And the caveat that it probably would end up fitting once we understood things better, but it’s always important to follow up on these kinds of clues.

So now we understand things a bit better, and a number of people have been working to dig into this apparent anomaly. Here is a new paper from this week, that presents their own way of using these kinds of data to test GR against large-scale structure.

Testing General Relativity with Current Cosmological Data
Authors: Scott F. Daniel, Eric V. Linder, Tristan L. Smith, Robert R. Caldwell, Asantha Cooray, Alexie Leauthaud, Lucas Lombriser

Abstract: Deviations from general relativity, such as could be responsible for the cosmic acceleration, would influence the growth of large scale structure and the deflection of light by that structure. We clarify the relations between several different model independent approaches to deviations from general relativity appearing in the literature, devising a translation table. We examine current constraints on such deviations, using weak gravitational lensing data of the CFHTLS and COSMOS surveys, cosmic microwave background radiation data of WMAP5, and supernova distance data of Union2. Markov Chain Monte Carlo likelihood analysis of the parameters over various redshift ranges yields consistency with general relativity at the 95% confidence level.

One issue, as we noted way back when, is that it’s very hard to “test GR” without committing yourself to a model of the mass and energy sources that are causing the curvature of spacetime. So the game is to make some plausible assumptions and see where you go from there. This group seems to have assembled a sensible framework for testing deviations from Einstein, and come back with the answer that everything is on the right track.

We keep getting new and better data, of course, so we’ll keep testing. I suspect Einstein will continue to be right, but probably a lot of people thought Newton would continue to be right a century ago.