1. Black holes are regions of space where gravity is so strong that nothing, not even light, can escape. They form when massive stars collapse at the end of their life cycles. 2. There are two main types of black holes - static and rotating. The rotating type, known as Kerr black holes, form when collapsed stars have angular momentum. 3. As a star collapses, it passes through stages as a red giant, white dwarf, and neutron star until its mass exceeds around 3 solar masses, causing it to collapse entirely into a black hole with a singularity at its center.

1. BBllaacckk HHoolleess
RRaannjjiitthh SS

2. A huge great enormous thing,
like — like nothing. A huge big
— well, like a — I don’t know —
like an enormous big nothing ...
Piglet describes the Heffalump,
in Winnie the Pooh by A.A. Milne

3. HHuuggee GGrraavviittyy
• Black Holes are Gravity Centers of The
Universe
• Size ~ 0 and Density ~ a
• Two Types
– Static
• Karl Schwarzschild solutions
– Rotating
• Kerr solutions

4. CChhaannddrraasseekkhhaarr LLiimmiitt
• Death of Star
• Red Giant
• White Dwarfs
– Mass of star<1.4 Solar mass
– Electron Degeneracy Pressure
• Neutron Stars
– 1.4 solar mass<Mass of star<3.0 solar mass
– Neutron Degeneracy Pressure
• Black Holes
– Mass of star >3.0 Solar mass

5. TThhee TTrraannssiittiioonn
• Pauli Exclusion Principle:
No two electrons can occupy the same position in space
• Electron Degeneracy Pressure :- Electrons are packed
side by side in a white dwarf This prevents it from
collapsing any further
• Neutron Degeneracy Pressure : - Neutrons are packed
side by side in a Neutron Star This prevents it from
collapsing any further
• More Mass More Gravity :- Nothing can stop Collision
• -> Black Holes

6. EEvveenntt HHoorriizzoonn
• Area around Black Hole,
from where nothing can be
escaped to outside
• Inside event horizon escape
velocity is greater than
speed of light.
John Wheeler

7. SScchhwwaarrzzsscchhiilldd RRaaddiiuuss
Karl Schwarzschild
(1876-1916)
• Distance from
singularity to event
horizon is called
Schwarzschild radius
• Schwarzschild radius is
a measure of the size of
black hole

8. Black Hole
infinite abyss
in space-time
Albert Einstein
(1879-1955)

9. Falling into a
Black hole:
Time dilation

10. Spaghettification!

11. Singularity Theorem
• Every black hole must have a singularity
inside itself
• There is no existence of a naked
singularly in the universe

12. Naked Singularity
Roger Penrose
(b1931)
A singularity that is not inside a black
hole (not
surrounded by an event horizon), and
therefore
can be seen by someone outside it

13. CCoossmmiicc CCeennssoorrsshhiipp
HHyyppootthheessiiss
• The laws of physics prevent naked
singularities from forming when a star
collapses

14. NNoo--HHaaiirr TThheeoorreemm
• A black hole has almost no hair;
its only ‘hair’ are its
– mass
– angular momentum
– electric charge

15. TTyyppeess ooff BBllaacckk HHoolleess
• Schwarzschild (1916)
– mass
• Reissner-Nordström (1916, 1918)
– mass, electric charge
• Kerr (1963)
– mass, angular momentum
• Kerr-Newman (1965)
– mass, angular momentum,
electric charge
Roy Kerr

16. SSppaaccee--TTiimmee DDiiaaggrraamm

17. SScchhwwaarrzzsscchhiilldd BBllaacckk HHoollee

18. Kerr Black Hole

19. WWoorrmmhhoollee

20. PPeennrroossee PPrroocceessss --
EEnneerrggyy
eexxttrraaccttiioonn
ffrroomm aa KKeerrrr
bbllaacckk hhoollee
Event
Horizon Ergo sphere
Top View

21. Black Hole Dynamics
• First Law
• Second Law
• Third Law

22. First Law
• If a body with a fixed mass and angular
momentum is fall into a black hole then
the mass and angular momentum of the
black hole increases that much.
• Resembles with the First law of
thermodynamics
• Energy conservation theorem

23. Second Law
• The surface area of a black hole is not
reduced in any process
• If two black holes combined then the
resultant surface area is greater than the
sum of surface areas of each black
holes.
• Surface area ->Entropy
• We cannot reduce the entropy of a
system.

24. Third Law
• The surface gravity of a black hole is
never become zero.
• Resumbles to third law in
thermodynamics
• We cannot reduce the temp: to absolute
zero.

25. Virtual Particles
•In quantum theory, there is an intrinsic uncertainty
in energy and time: DE Dt ≥ h/4p
•This implies the existence of ‘virtual particles’
even in a vacuum
•Virtual particles appear in pairs, consisting of a
particle and its corres-ponding antiparticle

26. Hawking Radiation
Stephen W. Hawking
(b1942)
• One partner of a virtual-particle
pair could fall into a black hole,
carrying negative energy with it
• Effectively, the black hole appears
to be emitting particles and losing
mass!

27. But this effect is very tiny
for normal black holes
• For a solar mass black hole
– Temperature = 10-7 K
– Lifetime = 1067 years
(age of universe = 1010 years)
• Since T µ 1/M, this effect is more
pronounced for small black holes
• Mini black holes created during
the Big Bang?

28. Microlens event

29. Black hole in globular
cluster

30. Disk in galaxy NGC 7052

31. NGC 4438

32. Galaxy NGC 6251 nucleus

33. M87

34. Expanding Universe
• Gravitational Field Equations
 Expanding universe
" l Steady Universe
• Edwin Hubble and Milton
Heumanson (Mount Wilson
Observery)
• Expanding Universe
• Red Shift
Edwin Hubble

35. Freedman-Robertson-
Walker Model • Critical Mass
• Closed Universe
– Mu <Critical Mass
– Universe started Contracting after a particular time
• Flat Universe
– Mu = Critical Mass
– Expansion rate of universe become constant
• Open Universe
– Mu > Critical Mass
– Expansion rate increases with time

36. Possible Fates of the
Universe

37. Big Bang Theory
• Lemaither and Gamove
• Universe Formed from a Big Bang
• Singularity is Big Bang Singularity
• The total universe formed from
that. Lemaither
George Gamow

38. Picture

39. Pic

40. Big Bang Theory Proofs
• Background Radiation
• Large Scale of universe
• Distribution of Galaxies

41. Other Theories
• Stedy State Theory
• Inflation Theory
• Big Crunch Theory
• Oscillatory state Theory

42. Will the Universe
Recollapse?
• Gravitational pull of the galaxies on each other
is slowing down the rate of expansion
• Required density for the universe to
recollapse is 4.5 x 10-30 g/cm3
• Observed density of luminous material
(stars, galaxies) is about 3 x 10-31 g/cm3

43. Dark Matter
• But there may be about 10
times this amount
in the form of ‘dark matter’
• So the universe is very
close to the threshold
for recollapse!
Measurements of the velocities of stars in
a galaxy show that there must be more
matter in the galaxy than is apparent.
This ‘dark matter’ is known to form an
invisible halo around the galaxy

44. Gravitational Waves
• The Variations in space-time (When
body Accelerated) causes
Gravitational Waves.
• Speed of Wave = C
• Large gravity related Phenomena
• Supernova, Black Holes etc…

45. Gravitational Wave Detector
• When GW passing through a body it
will expands the body in that
direction and contracts in opposite
direction by measuring this we can
detect GW.

46. LIGO
• The Laser Interferometer
Gravitational-Wave
Observatory Caltech.

47. Forces of Nature
• Gravitational
• Electromagnetic
• Weak
• Strong

48. Standard Model - Quarks
• 6 Quarks
[up,down,top,bottom,strange,charm]
• Gluons – Exchange Particles
• Super Symmetry

49. Graviton
• Exchange Particle for Gravity

50. Unification of the Four Forces
• Electricity + Magnetism
= Electromagnetism
• Electromagnetism + Weak
= Electroweak
• Electroweak + Strong
= Grand Unified Theory
(GUT)
• GUT + Gravity
= Theory of Everything
(TOE)??

51. Gravity
• Due to geometry rather than exchange of
particles
• Remains impossible to incorporate within
the framework of quantum field theory
like the other forces

52. Quantum Gravity?
• Does space-time fluctuate in
a quantum fashion at very
small scales?
• Called space-time foam
• How to describe this
mathematically?

53. Superstring Theory
• Best candidate for a TOE is superstring theory
• Assumes all fundamental
particles are actually
string-like objects rather
than point-like objects
• Different particles correspond to different
vibrational modes of the same string

54. Point particles and
strings
interact differently

55. Extra Dimensions?
• Superstring theory
predicts that space-time
is 10-dimensional (9 space + 1
time)
• The extra 6 dimensions
are thought to
be rolled up to a very
small size

56. Unsolved Problems
• Why Gravity happens?
• No – Graviton in Standard Model
• Dark Mater

57. TThhaannkkss