Incredible " super-light speed " phenomenon.
M87 Jet generated by the black hole in the center of galaxy . When observing particle flows generated by high-energy astrophysical events, astronomers sometimes find them "super-light motion". NASA
The speed of light is the most unbreakable iron law in this universe. Relativity theory believes that any object in the universe can not move faster than the speed of light in a vacuum. But people occasionally discover the incredible "super-light speed" phenomenon in the universe.
Recently, some astronomers have discovered that a pair of neutron stars 140 million light years away from the Earth actually generated a flow of high-energy particles flying at super-light speed during the merger!
The pair of neutron stars is the focus because the gravitational wave triggered by their merger swept across the earth on August 17, 2017 (i.e. the gravitational wave event numbered GW170817). That was the first time that humans have detected gravitational waves generated by the merger of neutron stars rather than black holes.
In a comprehensive tracking observation, astronomers discovered that the merger of these neutron stars produced a flow of high-energy particles, and the flight speed of these particles actually seemed to be 7 times the speed of light.
Intuition tells us that this is impossible. Intuition is right. Although a few people believe that superluminal motion does exist, most scientists believe that it is actually an illusion, an illusion called "optical superluminal motion", and its principle is quite concise.
"Optical Superluminescence Movement" phenomenon occurs occasionally in the universe, and often occurs in celestial bodies or celestial events that can produce near-light jets. The reason why
causes illusions is related to the flight speed and direction of the particles. These particles fly extremely fast. Taking GW170817 as an example, the particles it produces have a flight speed of 99.97% of the speed of light. Such a fast speed leads to the consequence that when some of them fly towards us, as the distance from the earth continues to shorten, the time it takes for each flash we see to reach the earth continues to shorten.
In this way, if we observe these particles and calculate their speed of motion, mistakenly think that the distance between all these particles and the earth remains unchanged, we will underestimate the time interval when the flash occurs, overestimate their flight speed, and create an illusion that they are moving at several times the speed of light.
Reference
Optical superluminal motion measurement in the neutron-star merger GW170817
https://www.nature.com/articles/s41586-022-05145-7.epdf
