Time Machine

If a light emitting object is directly behind such a heavy lens, its image is smeared around the lens in a symmetric manner. This effect is named Einstein Ring. Naturally, such perfect alignment of a spherically symmetric lens behind and a light source behind it is extremely rare. Gravitational lenses also amplify the brightness of the lensed object.  The advent of high precision, full sky surveys measuring billions of objects, renders such rare events observable. 


More about the physics of Einstein Rings at horizoncrossing.com/2015/11/27…