Weak lensing and the Dyer-Roeder approximation

Understand

The distance-redshift relation plays an important role in cosmology.

• In the standard approach to cosmology it is assumed that this relation is the same as in the homogeneous universe.
• As the real universe is not homogeneous there are several methods to calculate the correction.
• The weak lensing approximation and the Dyer-Roeder relation are one of them.