The illusion of being faster than light:how a star problem was solved

Source– The post is based on the article “The illusion of being faster than light: how a star problem was solved” published in The Hindu on 19th October 2022.

Syllabus: GS3- Science and Technology

News- The article explains the new observation by scientists related to merging of neutron stars.

What is the new discovery?

In 2017, the Laser Interferometer Gravitational-Wave (LIGO) observatories recorded a signal. It indicated that two massive and dense stellar bodies had merged to form a third body, likely a black hole. From this merger, an unusual jet of matter was observed, which gave an illusion of traveling faster than light.

In a paper published in Nature, the scientists describe measuring the “apparent speed” of the jet to be about seven times the speed of light. They have measured the speed of the relativistic jet to be close to 0.9997c, where “c” is the speed of light.

It clears the doubt around the source of the jet travelling faster then light. These clearly are massive neutron stars merging to give a black hole and throwing off relativistic jets of particles in the process.

What are neutron stars?

Neutron stars are formed when a star reaches the end of its lifetime. They are formed by supernova explosions. They are extremely dense.

What is the phenomenon of illusion created by particles moving at seven times the speed of light?

This happens in cases where a source moves towards us with a velocity that is very close to light’s velocity. This phenomena happens in the case of black holes. It was also known earlier.

The present measurements and observations made with GAIA data amount to measuring the position of an object in the sky.

Normally, if we make these measurements from earth-based telescopes, it would require data from radio telescopes spaced apart by intercontinental distances. This technique is called Very Long Baseline Interferometry (VLBI) and was used in the earlier papers. But the newly measured has better precision than VLBI technique.

What are the impacts of study?

We have learnt that neutron star mergers can result in relative speed very close to light. It is better than the earlier VLBI technique.

It strengthens the hypothesis that such neutron star mergers are responsible for a class of gamma-ray bursts. Gamma-ray bursts are flashes of extreme gamma ray photons that release a huge amount of energy. They come from different galaxies in the universe and are observed here quite frequently.