THE GIST of Editorial for UPSC Exams : 13 APRIL 2019 (Seeing darkness: the first image of a black hole (The Hindu)

Seeing darkness: the first image of a black hole (The Hindu)

Mains Paper 3 : Science and Technology
Prelims level : Black Hole
Mains level : Discoveries of space science

Context

• On April 10, the Event Horizon Telescope collaboration showed the world the ‘unseeable’: the very first image of a black hole.
• The black hole itself cannot be seen, because light cannot escape its intense gravitational attraction.
• The so-called event horizon that envelops the black hole is the point of no return and any object transgressing this boundary is lost. Just outside is a region where a photon (light quantum) can orbit the black hole without falling in.
• This is called the ‘last photon ring’, and this is what the EHT imaged, seeing in effect the silhouette of a black hole. About a hundred years after the black hole made its way into physics through Albert Einstein’s general theory of relativity.

LIGO collaboration

• After the LIGO collaboration first directly observed the gravitational waves made by the merging of two black holes, the ‘dark star’ had finally been imaged.
• The Higgs boson was detected 50 years after it had been postulated, and gravitational waves were observed a century after Einstein predicted them.
• Visual proof of the existence of black holes comes a century after they appeared in scientific literature. In a collaborative effort, eight telescopes around the world were used for the experiment.
• The challenges included making each observe the same broad range of wavelengths around 1.3 mm and having precise atomic clocks at each location, so the data could be combined.
• A black hole marks the end of spacetime as commonly understood, and nothing that enters it can escape from the tremendous gravitational attraction.

Way forward

• However, this is no real danger, as black holes are located at distances that humans do not have the power to scale.
• The EHT set out to image two candidate supermassive black holes — Sagittarius A*, which is 26,000 light years from the earth, at the centre of the Milky Way, and another which is 55 million light years away at the centre of the Messier 87 galaxy in the Virgo galaxy cluster. But the first image was of the more distant one.
• The very long baseline interferometry technique linked radio dishes of telescopes across the world to produce a virtual telescope the size of the earth.
• This was needed to obtain the high resolution required for this measurement. Combining data from telescopes, each with different characteristics, was a separate challenge.
• Cutting-edge developments from computer science related to image recognition were used.
• This experiment endorses the diversity of collaboration just as much as it does unrelenting patience and good faith in the power of science and reason.

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General Studies Pre. Cum Mains Study Materials

Prelims Questions:

Q.1) Solar-powered Aquila drone is being specially designed to
a) Perform surveillance of sensitive areas in Afghanistan after the withdrawal of USA armed forces
b) Deliver internet service to remote areas of the world
c) Transport retail consumer packets to mega corporations in the European countries
d) Generate solar power and transit it wirelessly to regions facing acute power scarcit

Answer: B

Mains Questions:
Q.1) The first image of a black hole is a reassurance of science and reason. Explain.