Weak Gravitational Lensing
While the presence of any mass bends the path of light passing near it, this effect rarely produces the giant arcs and multiple images associated with strong gravitational lensing. Most lines of sight in the universe are thoroughly in the weak lensing regime, in which the deflection is impossible to detect in a single background source. However, even in these cases, the presence of the foreground mass can be detected, by way of a systematic alignment of background sources around the lensing mass. Weak gravitational lensing is thus an intrinsically statistical measurement, but it provides a way to measure the masses of astronomical objects without requiring assumptions about their composition or dynamical state.
Read more about Weak Gravitational Lensing: Methodology, Weak Lensing By Clusters of Galaxies, Galaxy-galaxy Lensing, Cosmic Shear, See Also
Famous quotes containing the word weak:
“He who knows that power is inborn, that he is weak because he has looked for good out of him and elsewhere, and, so perceiving, throws himself unhesitatingly on his thought, instantly rights himself, stands in the erect position, commands his limbs, works miracles; just as a man who stands on his feet is stronger than a man who stands on his head.”
—Ralph Waldo Emerson (1803–1882)