1) A black hole is an object with such strong gravity that not even light can escape, forming at the collapse of a massive star. 2) It has an "event horizon", the point of no return beyond which nothing, not even light, can escape the black hole. 3) Black holes were first theorized by geologist John Michell in 1783, and the modern theory was proposed by physicist Stephen Hawking.

1. PRESENTED BY:
S.HABINAYA.

2. 


A black hole is an object
with such powerful gravity
that nothing can escape from
it, including light. It is result
of deformation of space time
caused by the very compact
mass.
In black hole there is an
undetectable surface which
marks the point of no return,
called an “Event Horizon”.
It is called “Black” because
it absorb all the light that hit
it reflect nothing, just like
the perfect black body.

3. 
The idea of a body so massive that even light could not
escape was first put forward by geologist John Michell in
1783.

In 1935, Subrahmanyan Chandrasekhar also prove the black
star by the theory of “ White dwarfs” which led to an
understanding of mass limits that decide whether a star will
die as a white dwarf, neutron star or black star.

The modern theory of black bole is proposed by Stephen
Hawking.

4. 



“Normal Sized” Black
Holes
Microscopic
(Primordial) Sized
Super-Massive Black
Holes (On the order of
millions to billions of
Solar Masses)
(Estimated 3 million
solar masses for Milky
Way Black Hole)

5. 

There are many theories to that question. Most common theory is
where a colossal star with a mass of more than 3 times the sun’s
reaches the end of its life, gets crushed under its own
gravity, leading behind a compact black hole
When a gigantic star reaches the final stage at its life and is about
to go supernova, it spends all the nuclear fuel by then. So it stop
burning and heating up and cannot create the nuclear energy
required to feed the star.

6. 
Although black come in a
variety of masses and
sizes, their structures are all
alike. A black hole’s entire mass
is concentrated in an almost
infinite small and dense point
called a singularity. This point
is surrounded by the event
horizon. And a rotating black
hole is surrounded by the ergo
sphere, a region in which the
black hole drags space itself.
The radius of the black hole is
called “schwarzschild radius”.

7. 
Once a black hole has
formed, it can
continue to grow by
absorbing additional
matter. Any black
hole will continuously
absorb gas and
interstellar dust from
its direct
surroundings and
omnipresent cosmic
background radiation.

8. 
Black hole are so
massive that nothing,
not even light, can
escape its path. So that
means that even stars
and asteroids or much
less any thing in its path
would get sucked up
and
crushed
into
absolutely nothing. So
yes there are dangerous.

9. 
According to the general relativity there is no limit to the size
of a black hole. But a full of how gravity works must also
include quantum mechanics and such a theory has yet to be
constructed. Some hits from recent work on this theory
suggest that a black hole can be no smaller than about “10 to
the (-33) cm in radius”.
0.000000000000000000000000000000001 cm.

10. 

There is no limit to how large a black hole can
be. However, the largest black hole are thick
are in existence are at the centres of many
galaxies, and have masses equivalent to about a
billion sun(i.e., a billion solar masses). Their
radii would be considerable fraction of the
radius of our solar system.
The size of a black hole if defined by its mass.
For a given mass, there is a length called the
Schwarzschild radius which is proportional to
the mass.

12. 


There are so many types of black hole are in the
universe they are impossible to count it.
The milky way galaxy contain about 100 billion
stars. Roughly out of that 1000 stars that firm is
massive enough to become a black hole. The
nearest one is some 1,600 light year from earth.
The most massive black hole was discovered
by hubble space telescope at 10th january 2008.
Its mass is equivalent to small galaxy.

13. 

Along
with
Thomas
Hertlog at CERN, in
2006, Hawking proposed
a theory of “Top down
Cosmology” Which say
that the universe had 0
unique initial state
Stephan
Hawking
proposed that microscopic
Black hole formed in huge
explosion that gave birth
to the universe.

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