STORY OF THE BLACK HOLE AT THE MILKY.
                     STORY OF THE 
BLACK HOLE AT THE 
MILKY WAY’S 
CENTRE
Introduction
On October 6, the Nobel Prize for physics was awarded to 
Reinhard Genzel and Andrea Ghez for the discovery of a 
supermassive compact object at the center of our galaxy, and to 
Roger Penrose for the discovery that black hole formation is a 
robust prediction of the general theory of relativity.
Source: science.thewire.in
Black Holes 
Black holes are one of the most enigmatic objects in the 
universe, and they have fascinated scientists and non-scientists 
alike. 
In the 18th century, based on Isaac Newton’s work, John Mitchell 
and Pierre-Simon Laplace first proposed the idea of objects so 
heavy that even light couldn’t escape their gravitational pull.
Source: science.thewire.in
Einstein’s Theory 
Einstein’s theory contained a set of equations that could be used 
to determine the strength and direction of the force of gravity 
exerted in any natural situation. 
The German physicist Karl Schwarzschild determined the 
curvature of space-time around a spherical object, which 
physicists later found in nature in the form of black holes.
Source: Live Science
Location of Blackhole
Following the work of the American physicists Robert 
Oppenheimer and Hartland Snyder in 1939 and of David 
Finkelstein in 1958, we now understand these ‘locations’ a bit 
differently. 
The center of the object is known as the singularity. The surface 
of the sphere described by the Schwarzschild radius is called the 
event horizon.
Source: NASA
Point of No Return
The singularity at the centre of a black hole is formed when too 
much matter is crammed into too small a space, and the density 
becomes infinite. 
The event horizon is the ‘point of no return’: once something, 
including light, has crossed beyond this point in the black hole, 
there is no escape. 
Source: NASA
Approximations
Einstein had previously speculated that such ultra-compact 
masses can’t exist.
Several other physicists also thought that such ‘singularities’ 
might be artefacts of approximations and assumptions in the 
theory itself, and not something we might observe in the natural 
universe.
Source: science.thewire.in
 Singularity
If you have a bunch of particles sitting at rest with respect to 
each other, they will eventually come together and form a 
singularity. 
In reality, there are other forces in play between particles that 
prevent them from collapsing into a singularity every time they 
come close enough.
Source: phys.org
Penrose’s Theory on Blackhole
Penrose showed that if light becomes trapped inside some 
region and cannot escape, then a singularity must occur and the 
path of light will lead to the singularity. This trapped surface is 
the event horizon of a black hole.
Source: The Tribune India
Brighter light originating from 
the Milky Way
Astronomers found the objects associated with distant galaxies, 
many of which were more than a billion light-years away. 
Even at such distances, their light was thousands of times 
brighter than all the light originating from the Milky Way.
In astronomical terms, this is a blink of the eye.
Source: Scientific American
Quasars
Only a supremely dense object could produce such extreme 
brightness and rapid flickering. 
No wonder then that astronomers quickly suspected quasars 
could be supermassive black holes surrounded by superhot, 
radiation-emitting plasma.
Source: Daily Mail
BLACK HOLE AT THE MILKY 
WAY’S CENTRE
Donald Lynden-Bell, a physicist, provided theoretical descriptions 
of quasars, and suggested that most galaxies contain 
supermassive black-holes at their centres. 
In 1971, Lynden-Bell and Martin Rees, compared a map of 
quasars to radiation coming from the Milky Way. 
Based on their analysis, they predicted that the Milky Way 
should also host a massive black hole at its center.
Source: National Geographic
Thank You