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
- 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
- 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.
- After the LIGO collaboration first directly observed the gravitational
waves made by the merging of two black holes, the ‘dark star’ had finally
- 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
- 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
- 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
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
d) Generate solar power and transit it wirelessly to regions facing acute power
Q.1) The first image of a black hole is a reassurance of science and
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