Impulse Speeds...

The simulated radio images in this not-to-scale artist's illustration show superfast jets blasting from the black hole created by the merger of two neutron stars, a dramatic event observed in August 2017. In the 155 days between two observations, the jet appeared to move 2 light-years, a distance that would require it to travel four times faster than light. This "superluminal motion" is an illusion created as the jet is pointed nearly toward the Earth; it is actually moving at about 97 percent light speed.
Credit: D. Berry, O. Gottlieb, K. Mooley, G. Hallinan, NRAO/AUI/NSF

Topics: Astrophysics, Cosmology, Einstein, Special Relativity, Star Trek

The dramatic neutron-star merger that astronomers spotted last year generated a jet of material that seemed to move at four times the speed of light, a new study reports.

"Seemed" is the operative word here, of course; the laws of physics tell us that nothing can travel faster through space than light. So, the superluminal motion was an illusion, which was caused by the jet's (still very fast) speed and the fact that it blasted almost directly at us, researchers said.

"Based on our analysis, this jet most likely is very narrow, at most 5 degrees wide, and was pointed only 20 degrees away from the Earth’s direction," study co-author Adam Deller, of the Swinburne University of Technology in Australia, said in a statement from the National Radio Astronomy Observatory (NRAO), a facility of the U.S. National Science Foundation (NSF).

Faster Than Light? Neutron-Star Merger Shot Out a Jet with Seemingly Impossible Speed
Mike Wall, Space.com