The result can be that duplicate images of distant objects are produced from slightly different points in time.
More recently, the allied phenomena of gravitational reflections has been identified by researchers from the Astronomy Field Station established by the University of Burgerweldt on the summit of Mt Coatopakrat in Peru.
Observing on top of a somewhat active volcano presented certain technical challenges, but promising reports from the inaugural Lake Tutti Frutti Star Party made the faculty decide it was worth the effort.
Elementary precautions such as the construction of reinforced concrete bunkers, with walls fourteen metres thick and proof against both lava bombs and rocket propelled grenades, to house resident astronomers were taken, while the twin turrets with coaxial 40mm canon and 50 calibre machine guns were installed largely for their deterrent effect rather than to be actually used against local rebel armies - Hopefully.
In the dry thin air, the 2 metre telescope and associated instrumentation works to optimum levels.
The most exciting discovery over recent months has been the gravitational mirror effect detected in the Centaurus galaxy cluster which is well placed for observing from southern latitudes.
It seems that 470 of these galaxies are arranged in a saucer like formation extending over a diameter of 870 million light years, and the gravitational strings connecting this network are woven into such a close structure that the density is strongly differentiated from the thin intergalactic medium and forms a coarse gravitational mirror.
This mirror was used as a Herschellian reflecting telescope with an electronic eyepiece operating in the ultrared wavelength and has provided stunning images of galaxies and quasars half way between our planet and the Centaurus cluster.
Visiting Professor, Baron Beavis von Buttkopf is preparing a major paper to be published in a further issue of Alternate Universe on significant discoveries being made with this instrumentation, which include the first images of black holes seen contrasted against the bright backgrounds of emission nebulae.