Way back, there were observations of 'giant galactic arcs', with all kinds of speculation as to their nature. Now we know it was simply an effect of gravitation

Way back, there were observations of 'giant galactic arcs', with all kinds of speculation as to their nature. Now we know it was simply an effect of gravitational lensing. These excitable and far-flung statements about 'parallel universes' remind me of some of those early arc reports...