BLACK HOLES
Biggest one of many mysteries of Universe, can’t be seen can
only be detected by changes in the surrounding space-time fabric. As the name
suggests they are black and can be similar to hole formed in the space-time
fabric.
Ever wondered why they are black?
Objects can be seen only if they reflect light; well in case
of a black hole its gravitational pull is very intense that even particles
moving at 3x108m/s or light cannot escape. Escape velocity of earth
is 11.2km/sec. Black hole occurs where there is immense mass in small volume,
we know from Einstein’s theory of relativity that more the mass , more the
warping of space-time, and more the gravity.
To give an idea of mass contained in a black hole, shrinking
the earth to size of golf ball without removing any of its mass gives us a small
black hole.
HOW ARE THEY FORMED?
Dying stars whose
mass is 20 times mass of sun or more form black holes. Stars shine due to
enormous amount of heat liberated in nuclear fusion process. Stars are formed
from condensed gases (mostly hydrogen nucleus ), these gases are stay put due
to gravity which is also powerful enough
to crush the star. But these hydrogen nuclei gets fused together to form helium
and thereby releasing large amounts of energy (E=MC2), this process
is called nuclear fusion and this energy released tends to explode the star. As
a result, gravity and nuclear fusion in star’s core are at a war, till the core of
star runs out fuel and gravity Wins. Fate of the star hence forth is decided by
its mass, in case of black holes we focus on super massive stars, gravity
crushes the star aiming to form a singularity (infinite mass at one point).
Black holes are primarily of singularity within and an event
horizon. Event horizon is also called “The point of no return”, because once
you enter beyond this event horizon black hole sucks you to singularity and is impossible
to escape its tug.
WHAT IS IT LIKE TO FALL INSIDE A BLACK HOLE?
Time slows down inside a black hole, and at singularity time
stops, laws of physics as we know, breaks down. Assume an unfortunate astronomer
falls into a black hole, he will not realize it until he passes event horizon. Now,
he undergoes a process called spaghettification(being stretched like a spaghetti) that is, gravitational pull at
his head and feet is not same, it would stretch him and tear him apart. To his
friends in spaceship orbiting the black hole, it appears as the astronaut slowed
down and stopped at the event horizon, his time stops here.
Just for the sake of fun, we assume he overcame this
spaghettification process and manages to reach center of black hole alive. Here
starts our science fiction(interstellar, star trek, star wars), unproved theories(hypothesis),
it could be a gateway to another universe, you could visualize present, past
and future at once, time travel could be possible and much more.
DID U KNOW: There is a massive black hole at the center of
our own Milky Way galaxy; as a matter of fact every galaxy has a black hole at
its center. They are capable of destroying entire galaxies
Firstly, nice presentation of the article.
ReplyDeleteMy question is : Is the event horizon occurs only at a particular radius? Can event horizon of a black hole vary accordingly?
Thank You
DeleteEvent horizon is a place where the events that occur beyond it is not visible to outside observer because light cannot escape this gravity and we can see anything only if it reflects light.
And yes, event horizon occurs from The Schwarzschild Radius (for more information https://en.wikipedia.org/wiki/Schwarzschild_radius)
yes,Event horizon varies according to density of the black hole :)
Density of the black hole!!? How do we even obtain that?
DeleteDensity is mass over volume
DeleteWhich stars become blackholes is destined by how much mass star has...when it dies, this huge mass is compressed into minimum volume thereby making it highly dense which leads to a black hole