The document provides information about black holes from a physics group at Jahangirnagar University. It discusses the history of black hole theory, what a black hole is, how they form from massive stars, their properties including singularities and event horizons, evidence of their existence, Stephen Hawking's contributions, and some facts about black holes. The document contains sections on the history, formation, properties, detection, Hawking's work, and interesting facts about black holes. It aims to explain black holes and solve the mystery of these astronomical objects.

1. DEPARTMENT OF PHYSICS
JAHANGIRNAGAR UNIVERSITY
WELCOME
TO SOLVE THE MYSTERY OF BLACK HOLE !!

2. * RAHNUMA SHAHRIN RISTA (154)
* RABEYA AKTER RABU (156)
* MAHMUDUL HASAN SHORON (161)
* S.M. HASIBUL HOQUE (163)
* AKASH CHONDRA DAS (2120)
Group members:
GROUP-06

3. Contents:
 History of Blackholes
 What is a Blackhole?
Properties And Structures
Formation & Evolution
 Detection & Observational Evidence
 Contribution of Stifen Hawking
 Some fascinating facts about Blackhole

4. HISTORY OF BLACKHOLE

5.  French scientist Pierre-
Simon Laplace (1749-
1827) was one of the first
to discuss the possible
existence of black holes.
 American physicist
John Archibald Wheeler
first introduced the term
black hole in 1967 and
led many important
studies into their
properties.

6. HISTORY
• In the 18th century John Michel and Pierre-Simon Laplace
first mentioned about the objects with a huge gravitation, from
which even light cannot escape.
• In 1915 Albert Einstein developed the theory of general
relativity.
• Karl Schwarzschild finds black holes as a solution to
Einstein’s equations (1916)
• Robert Oppenheimer and Hartland Snyder predict that
massive stars can collapse into black holes (1939)
6

7. 7
1967: Term “Black Hole” coined
1970’s: Convincing evidence that black holes are real
Today: NASA space telescopes have discovered evidence
for black holes throughout the universe
Albert Einstein

8. WHAT’S A BLACK HOLE?
A black hole is one of the strangest objects in
space. It is an area in space where gravity is so
strong that even light cannot escape from it.
Since light cannot escape from a black hole, it
appears black. Light can travel faster than
anything we know with a speed of 300,000
kilometers per second. If light cannot escape
from a black hole, nothing else that we know
can.
A black hole is not really a hole and it is not
empty. It is filled with a lot of material crammed
into an extremely small space. This is what
gives a black hole its super strong gravity.

9. 9
What did Einstein say about Gravity?
Objects and light moving near the massive object are
forced to take a curved path around the object.
Just like the Moon orbiting Earth.
Images courtesy of Professor Gabor Kunstatter, University of Winnipeg

11. FORMATION OF BLACKHOLE

12. CREATION OF A BLACK HOLE (DEATH OF A STAR)

13. Formation of black holes
• Formed when a star collapses
• Collapse of star produces Neutron star & Black Hole
• Compression of any object into its Schwarzschild
radius gives a Black Hole

14. DO ALL STARS BECOME STELLAR-MASS BLACK HOLES?
It all depends
on the amount
of mass stars
contain
Mass <1 sun
Mass < 3 suns
Mass < 8 suns
Becomes
a white dwarf
Becomes
a neutron star Becomes
a black hole
http://www.nasa.gov/audience/forstudents/k-4/stories/what-is-a-black-hole-k4.html

15. A very small patch of our
Milky Way galaxy in the
constellation Sagittarius. In
total, our galaxy contains
some 100 billion stars and
100 million black holes.
Any small patch of the sky
shows many distant galaxies.
Each probably contains a
supermassive black hole and
millions of stellar-mass black
holes.

16. PROPERTIES
&
CLASSIFICATIONS

18. Singularity
 Density= ∞?
 Volume= 0?
 Surface area= 0?
 Gravity= ∞
Singularity

19. Event horizon :
 Completely black and reflects nothing.
 Once entered no escaping back.
 Empty and full of gravity.

21.  The Kerr black hole has the following parts:
Singularity - The collapsed core
Event horizon - The opening of the hole
Ergosphere - An egg-shaped region of distorted space around the event horizon
(The distortion is caused by the spinning of the black hole, which "drags" the
space around it.)
Static limit - The boundary between the ergosphere and normal space
 THERE ARE TWO TYPES OF BLACK HOLES:
SCHWARZSCHILD - NON-ROTATING BLACK HOLE
KERR - ROTATING BLACK HOLE
THE SCHWARZSCHILD BLACK HOLE IS THE SIMPLEST BLACK HOLE, IN
WHICH THE CORE DOES NOT ROTATE. THIS TYPE OF BLACK HOLE ONLY
HAS A SINGULARITY AND AN EVENT HORIZON.
THE KERR BLACK HOLE, WHICH IS PROBABLY THE MOST COMMON
FORM IN NATURE, ROTATES BECAUSE THE STAR FROM WHICH IT WAS
FORMED WAS ROTATING. WHEN THE ROTATING STAR COLLAPSES, THE
CORE CONTINUES TO ROTATE, AND THIS CARRIED OVER TO THE BLACK
HOLE (CONSERVATION OF ANGULAR MOMENTUM).

22.  A rotating black hole has an ergo sphere around the
outside of the event horizon.
 In the ergo sphere, space and time themselves are dragged
along with the rotation of the black hole

24. Even though we cannot see a black hole, it does have three
properties that can or could be measured:
 Mass
 Electric charge
 Rate of rotation (angular momentum)
As of now, we can only measure the mass of the black hole
reliably by the movement of other objects around it. If a black
hole has a companion (another star or disk of material), it is
possible to measure the radius of rotation or speed of orbit of
the material around the unseen black hole. The mass of the
black hole can be calculated using Kepler's Modified Third
Law of Planetary Motion or rotational motion

25. 25

26. According to his origin, theoretically there can exist at
least three classes of black holes:
According to the mass:
 Black supermassive holes: With masses of several million solar
masses. They would be situated in the heart of many galaxies.
They are formed in the same process that gives origin to the
spherical components of the galaxies.
 Black holes of stellar mass: They are formed when a star of
mass twice major that of the Sun turns in supernova and
implosion . His core centers in a very small volume that every
time is diminishing more. This one is the type of black holes
postulated by the first time inside the theory of the general
relativity.
 Mike black holes: They are hypothetical objects, something
smaller than the stellar ones. If they are sufficiently small, they
can evaporate in a relatively short period by means of emission
of Hawking's radiation. But they cannot be generated by a
conventional process of gravitational collapse, which needs
masses superior that of the Sun.
26

29. OBSERVATION AND DETECTION
OF
BLACKHOLES

30. 30
Nobody has literally seen a black hole yet, but
there are instruments with which astronomers
detect and study their X-ray emissions and their
effects over matter.

31.  Black holes can detected by their gravitational
effects on nearby stars or by the intense core of
light they produce in the center of galaxies when
astronomers studies the speed of the gases in the
cores of such galaxies.
 By these observations, they calculate the mass
and power of the black holes.

32. KECK
OBSERVATORY
HAWAII

33. Here is the Hubble Space Telescope, the first amazing
object to take a picture of a black hole.

34. STEPHEN HAWKING
Stephen Hawking was a very
important scientist that has studied a
lot about black holes. He investigated
and discovered that some black holes
emited a special type of radiation. For
this reason, this radiation is called
Hawking radiation.
He has also written a book about
black holes, which is called Black
Holes and Baby Universes and Other
Essays.

35. Contribution of Stephen Hawking
Black holes evaporate eventually by phenomenon Hawking Radiation

36. In 1974, Hawking predicted that
black holes are not entirely black
but emit small amounts of thermal
radiation which is known as
Hawking radiation.
By applying quantum field theory
to a static black hole background,
he determined that a black hole
should emit particles that display
a perfect black body spectrum.
Since Hawking's publication,
many others have verified the
result through various
approaches.

37. BLACK HOLE SEEN IN CLOSEST LOOK EVER
 September 4, 2008—A super massive black hole at the
center of the Milky Way has wound up in the crosshairs of a
virtual telescope spanning 2,800 miles (4,506 kilometers).
Though unproven, there is strong evidence for the
existence of black holes.

38. The Large Hadron Collider is a 17-mile long particle accelerator in Switzerland
that may reach energies high enough to create miniscule black holes.

40. WHAT HAPPENS IF YOU FALL INTO A BLACK HOLE?

41. FALLING INTO A BLACK HOLE
 The pulling force would increase as you moved toward
the center, creating what's called a "tidal force" on your
body.
 If you fell into a large enough black hole, no one
outside would be able to see you, but you'd have a view
of them. Meanwhile, the gravitational pull would bend
the light weirdly and distort your last moments of vision.
41

42. WHAT HAPPENS TO A SPACESHIP THAT FALLS INTO A
BLACK HOLE?
 We can escape from the surface of Earth in a spaceship if
the spaceship is accelerated fast enough (about 11
km/sec) similarly you would need a force that could
accelerate your spaceship to faster than the speed light
travels to escape from a black hole - and nothing we
know of can exceed the speed of light.
42

43. WHAT WILL HAPPEN WHEN TWO
BLACKHOLE COLLIDE ???
43

45. 45
WHAT WILL HAPPEN IF THE SUN TURNS
INTO A BLACKHOLE???

46. 46
Not to Scale

47. SUN AS A BLACK HOLE
 Only stars that weigh considerably more than the Sun end their
lives as black holes. The Sun is going to stay roughly the way it is
for another five billion years or so.
 If the Sun *did* become a black hole for some reason? The main
effect is that it would get very dark and very cold around here. The
Earth and the other planets would not get sucked into the black
hole; they would keep on orbiting in exactly the same paths they
follow right now.

48. 48
Including one giant black hole at the very center.
There are 200 billion stars in our galaxy, the Milky Way
There are also millions of black holes
How have we survived???

49. IS THERE ANY BLACK HOLE NEAR THE EARTH?
The nearest black holes
discovered at the moment are at
various thousands of light years away.
They are so far that they don’t have
any effect in the Earth neither in it’s
surroundings. It is believed that there
is a supermassive black hole in the
middle of our galaxy, the Milky Way, at
about 27.000 light years away.
Although it has millions of times the
Sun’s mass, as being so far it can’t
affect our Solar System.
27.000 light years

50. 50
How much would you “weigh”?
 On Earth, let’s say you weigh 150 lbs.
 On the Moon, you’d weigh 25 lbs.
 Jupiter, you’d weigh 350 lbs.
 On the Sun, you’d weigh 4,000 lbs.
!!! Near a Black Hole,
you’d weigh over
20 TRILLON POUNDS

51. DO YOU KNOW?
THERE EXISTS
WHITE HOLE ALSO…!!
51

52. White Holes
A white hole is the opposite of a black hole.
It forces objects to move out instead of a
black hole, which pulls objects in.

53. Relation between Black hole & Worm hole
But new research suggests that, if a speculative theory called loop
quantum gravity is right, white holes could be real
Worm hole warps space time Hypothesis only

54. 54
WHAT ARE SCIENTISTS TRYING TO LEARN?
X-ray: NASA/CXC/U. Wisconsin/A.Barger
et al.; Illustrations: NASA/CXC/M.Weiss
Credit: NASA, ESA, and A. Schaller (for STScI)
NASA missions continue to search for and study black holes to
determine the fate of matter as it falls into black holes, how
powerful jets form, and what role black holes played in the
formation of the early universe.

55. References :
• Kip Thorne, Black Holes And Timewarps (Norton, 1994)
• Alessandro Fabbri and Jos'{e} Navarro-Salas,Modeling Black Hole Evaporation
(Imperial College Press, 2005)
• John A. Wheeler, E.F. Taylor, Exploring Black Holes, Introduction to General
Relativity (Addison Wesley, 2000)
• Stephen Hawking, The Universe In A Nutshell (Bantam, 2001)
Images :
• http://chandra.harvard.edu/resources
• http://www.belmontnc.4dw.net/DWFNEU5.gif
• www.tqnyc.org/NYC040808/ neutron_star.jpg
• http://en.wikipedia.org
• www.scienceweek.at

56. Thanks for watching
this slide show on Black holes. Hope you
learned some facts about this amazing object
in the galaxy.