These objects are subject to the so-called "odd number theorem," which does not hold in the case of a cosmic string.
These objects are subject to the so-called "odd number theorem," which does not hold in the case of a cosmic string. They give rise to a Shapiro effect that combines with optical path differences to produce time delays between different rays. The weak-field limit gives twice the Schwarzschild radius over the impact parameter for the deflection angle, while the strong- field limit is characterized by arcs and multiple images. A source on the line of sight to one of these will produce an Einstein ring. FTP name these phenomena in which a massive object deflects and focuses light from a background source.
These objects are subject to the so-called "odd number theorem," which does not hold in the case of a cosmic string.
{gravitational lens}es