Powerpoint Presentation by Sarath Tharayil. saraththarayil@gmail.com www.fb.com/sarathtsreenivasan

1. Black Holes
PowerPoint Presentation by:
Sarath.T.S
sarathtahrayil@gmail.com

2. What is a ‘Black Hole’ ?
• A black hole is a region of space-time from
which gravity prevents anything, including
light, from escaping.
• The theory of general relativity predicts that a
sufficiently compact mass will deform space-time
to form a black hole.
• Objects whose gravitational fields are too
strong for light to escape were first considered
in the 18th century by John Mitchell in a letter
written to Henry Cavendish in 1783 of the Royal
Society

3. Black Holes: A Theoretical Definition
l An area of space-time with a
gravitational field so intense that its
escape velocity is equal to or exceeds the
speed of light
lThe Important thing is that this area can
be of any size.
lMost Black Holes are believed to come
about from the death of massive stars.

4. Some Terms Related to
Black Holes

5. Event Horizon
• The boundary of the black holes from
which no escape is possible is called the
event horizon.
• Nothing, not even light, can escape
from inside the event horizon.
• The shape of the event horizon of a
black hole is always approximately
spherical.

6. Singularity
• At the centre of a black hole as
described by general relativity lies a
gravitational singularity.
• It can also be shown that the singular
region contains all the mass of the
black hole solution. The singular region
can thus be thought of as having
infinite density.

7. Types of Black Holes
Black Holes
Stellar Black
Holes
Intermediate-
Mass Black
Holes
Super Massive
Black Holes

8. Types of Black Holes
• Stellar black holes are objects with approximately 4–15
M☉.
• Intermediate-mass black holes range from 100–10000
M☉.
• Super massive black holes are in the range of million or
billions M☉.

9. Where Could Super-Massive Black Holes Exist?
• The only known places in
the Universe where there
could be enough mass in
one area is in the center of
massive galaxies
• Not believed to be
anywhere else
• In our Galaxy, Sagittarius A
may be a potential Super
Massive Black Hole.

10. Black Hole Formation

11. Chandrashekar Limit
• The Chandrasekhar limit is the
maximum mass of a stable white
dwarf star.
• The currently accepted value of the
limit is about 1.39 M☉
( 2.765 × 1030 kg)

12. Conclusion
• Black Holes are celestial structures which has a very high mass and
due to it has a high gravitational field for itself.
• From black holes even light can’t escape.
• A star after its death may or may not become a black hole
depending upon the mass.
• The accepted facts about black holes may change over time.
• Our sun can’t transform to a black hole.

13. Fate of Universe?
• All Black Holes Evaporate over time due to Hawking Radiation.
• Eventually the Universe will have no matter and all there will be
left is radiation.
• Evaporation Time:
1 * 10^-7 (M/M sun)^3 Years
On order of 1* 10^20 years

14. How a star be consumed by a Black Hole?

15. Thank You