Dark energy, in the form of a cosmological constant (Λ), has been seen as responsible for the accelerating expansion of space, holding a steady energy density.

Gravitational lensing often evokes images of a cosmic funhouse mirror: duplicated galaxies, dramatic arcs and distorted shapes. But the web-like, large-scale structure throughout the universe also bends light in a weaker,

Scientists are homing in on the nature of a mysterious force called dark energy, and nothing short of the fate of the universe hangs in the balance