Updated: March 5, 2016
21:17 IST
C.V. Vishveshwara:
the black hole man of India
·
The Hindu
Prof. C.V. Vishveshwara
is not only among the first in India to study black holes, but also the one who
made a very important calculation that was used in this discovery. Photo:
Bhagya Prakash K.
·
A humorous take on the
No-hair theorem where Occam's razor chops the hair off a black hole.
The discovery of gravitational waves has
shaken the world – literally, when the wave was detected, on September 14, 2015
and figuratively, when it was announced in February. One of the people at the
heart of this discovery is a 77-year-old Bangaluru-based Professor Vishweshwara
who is not only among the first in India to study black holes, but who has also
made a very important calculation that was used in this discovery.
To recap briefly, about 1.3 billion years
back, two black holes, of masses 36 and 29 times that of the sun, merged to
form a unit. This cataclysmic event shook the fabric of space-time and emanated
a characteristic disturbance, which our scientists have detected using the
advanced LIGO (Laser Interferometer Gravitational Wave Observatory) detectors.
The black holes first came close to each other, then locked in circular orbits
and then abruptly merged. The corresponding signal would also have three parts,
the inspiral, merger and ringdown. The beauty is that this waveform was recorded
and the last part is akin to a bell, ringing and fading away.
It is for this portion of the calculation
that we have to thank Professor Vishveshwara. The “ringdown” signal, arising
out of a black hole merger, originally called the “quasinormal modes” was first
predicted by him in a paper that he published in Nature in 1970. Not just that,
earlier he had worked out two important papers on the theory of black holes,
with famous general theory of relativity specialist, Charles Misner, as his
thesis adviser. At the time, the term “black holes” had not been coined and the
event horizon went by the name “Schwarzchild surface”.
“It was a natural question then to ask: how
does one see a black hole? So, using a computer, I scattered packets of
gravitational waves from a black hole and the quasinormal modes emerged
carrying the signatures of the black hole… this was theoretical. I had never
dreamed that this would take on an aspect of reality some day,” says Prof.
Vishveshwara, who is now the Emeritus Director of Jawaharlal Nehru Planetarium
which he founded.
As described earlier, the initial signal,
the “chirp”, the steadily increasing frequency and amplitude of the
gravitational waves indicates the inspiralling of two black holes and the ring
down ( or the quasi-normal mode, QNM) indicates the newly created black hole
after the merger.
“When I saw at IUCAA [Inter University
Centre for Astronomy and Astrophysics] the QNM recorded by LIGO, I felt the
same kind of euphoria that I had experienced 45 years earlier when they emerged
out of a computer — it was like time travel back into the past,” he says.
Prof. Vishveshwara is far from being a
bookish nerd. Among other things, he is interested in cartooning too. He says:
“I dreamt of becoming an artist… while working on the QNM in New York, I
studied painting at the Art Students’ League, which was reputed to be a
favourite haunt of many artists including Salvador Dali… Only after returning
to India did I start cartooning for conference proceedings, my own books etc.”
He laughingly adds that in 2005, Spektrum der Wissenschaft, a German science
magazine had published his Einstein cartoons — and paid for it too!
Scientists are many times given to whimsy
and there is one cartoon of his which combines the philosophical “law of
parsimony”, the Occam’s Razor with black hole physics. Occam’s Razor prescribes
simplicity and the shearing of all redundant complexity, made popular in The
Name of The Rose, by Umberto Eco; it states that among competing theses, the
one with the fewest assumptions must be selected.
When the discussion of whether there were
“hairy” fields coming out of a black hole (which resulted in the famous no-hair
theorem) came up, Prof. Vishveshwara presented an appropriate Occam cartoon
(shown here).
With his father, Padmashri C.K. Venkata
Ramayya, being a celebrated man of letters, Prof. Vishveshwara’s childhood,
filled with music, literature and banter, has endowed him with a ready wit. His
books “Einstein’s Enigma or Black Holes in My Bubble Bath,” and “Universe
Unveiled or the Cosmos in my Bubble Bath,” are hugely popular.
“The most unexpected finding I have seen is
that the universe is accelerating. We now have dark matter, dark energy, all
mysterious…is this the dark age of cosmology?” he quips. Winding up with a few
words about the latest LIGO discovery, he says,
“Gravitational waves had been predicted by
Einstein a hundred years ago and LIGO’s finding is a major event expected for
nearly thirty years. The wait is over and the future is bright.
http://www.thehindu.com/sci-tech/science/cv-vishveshwara-the-black-hole-man-of-india/article8318058.ece
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