Two teams at Fermilab and Berkeley Lab have independently made the largest direct measurements of the invisible scaffolding of the universe, using the gravitational lensing effect known as “cosmic shear” to build maps of the distribution of dark matter. Their methods show that surveys with ground-based telescopes can measure cosmic shear with enough accuracy to aid in better understanding the mysterious space-stretching effects of dark energy.

In an attempt to explain away invisible dark matter and dark energy, some theorists have offered new theories of gravity that try to improve on Einstein’s General Theory of Relativity. A new study inspired by the work of a Berkeley Lab cosmologist indicates that at least one of these new theories is wrong.

Berkeley Lab cosmologists were part of an international team that has extended the relationship between the x-ray luminosity and the mass of galaxy clusters as measured by gravitational lensing, improving the reliability of mass measurements of much older, more distant, and smaller galactic structures. These refined measurements will benefit both the understanding of dark matter and the nature of dark energy as well.

Gravitational lensing, which depends on Einstein’s Theory of General Relativity, directly tests its ability to predict the growth of large-scale structure.