The Royal Swedish Academy of Sciences on Tuesday announced the
Nobel Prize in Physics, with one half to Roger Penrose University of
Oxford, UK, “for the discovery that black hole formation is a robust prediction
of the general theory of relativity” and the other half jointly to Reinhard
Genzel and Andrea Ghez “for the discovery of a supermassive compact object at
the centre of our galaxy.”

Let’s understand what their discoveries are:

The awardees made their discoveries about one of the most
exotic phenomena in the universe, the black hole. Penrose showed that the
general theory of relativity leads to the formation of black holes. Genzel and Ghez
discovered that an invisible and extremely heavy object governs the orbits of
stars at the centre of our galaxy and a supermassive black hole is the only
currently known explanation.

Roger Penrose used ingenious mathematical methods in his
proof that black holes are a direct consequence of Albert Einstein’s general
theory of relativity.

In January 1965, ten years after Einstein’s death, Roger
Penrose proved that black holes really can form and described them in detail;
at their heart, black holes hide a singularity in which all the known laws of
nature cease. His groundbreaking article is still regarded as the most
important contribution to the general theory of relativity since Einstein.

Reinhard Genzel and Andrea Ghez each lead a group of
astronomers that, since the early 1990s, has focused on a region called Sagittarius
A* at the centre of our galaxy. The orbits of the brightest stars closest to
the middle of the Milky Way have been mapped with increasing precision.

The measurements of these two groups agree, with both
finding an extremely heavy, invisible object that pulls on the jumble of stars,
causing them to rush around at dizzying speeds.

Using the world’s largest telescopes, Genzel and Ghez
developed methods to see through the huge clouds of interstellar gas and dust
to the centre of the Milky Way.

“The discoveries of this year’s Laureates have broken new
ground in the study of compact and supermassive objects. But these exotic
objects still pose many questions that beg for answers and motivate future
research. Not only questions about their inner structure, but also questions
about how to test our theory of gravity under the extreme conditions in the
immediate vicinity of a black hole,” says David Haviland, chair of the Nobel
Committee for Physics.