Quasar-coloured lenses
EPFL News
Astronomers have viewed for the first time a distant galaxy magnified by the gravity of a quasar between it and Earth. The concept of a gravity lens was predicted by Einstein's theory of general relativity. Galaxy lenses that bend and focus the light of bright objects – like quasars – behind them have already been seen. Now a quasar is doing the same for another galaxy behind it.
So what?Gravity is a property of matter: the more matter, the greater the gravitational force. A quasar acting as a lens lets us estimate the force of gravity needed to bend light to form the magnified image then calculate the mass of the quasar's galaxy.