How is this related to time delays in gravitationallenses?
这与重力镜中的时间延迟有何关系？
2
And so far gravitationallenses have mainly been observed around clusters of galaxies.
到目前为止，和引力透镜主要观察周围的星系团。
3
Because of their heft, the clusters act like giant cosmic lenses, magnifying, distorting and bending any light that passes through them - an effect known as gravitational lensing.