We’ve all heard of gravitational lensing. Somehow, I missed the opposite. The word may be a bit informal.
demagnification:
[Martin Sahlén of the University of Oxford] and his colleagues invoke a new field that is added to a cosmological constant to change dark energy’s density, depending on the local density of ordinary matter. That means dark energy would have behaved differently at different times. In the early universe, matter’s density was high, and dark energy would have had very little effect. But as the universe expanded and became less dense, dark energy’s effects became more prominent, causing the expansion to accelerate as observed.
Such dark energy has an observable consequence: it causes space-time in large, under-dense regions known as voids to behave differently than if dark energy were a cosmological constant alone. Where regions of high density, such as galaxy clusters, warp space-time to bend light towards us like a magnifying glass, voids bend light away like a concave lens. Measuring the amount of such “demagnification” could help test the team’s model. [“Huge cosmic voids could probe dark energy,” Anil Ananthaswamy, NewScientist (8 January 2014)]
