Explanation:

What are black holes?

=> It is also a celestial body which have infinite gravitational force and infinite mass and even light can not escape from it.

How black holes formed?

=> Mostly black holes formed because of compression of mass and density of stars.

So, first we know how stars formed and then black holes.

= stars are formed by the cloud of gas and dust present in our universe which we simply called as Nebula.

= They are mostly composed of hydrogen and helium with some amount of another elements.

= when the density of nebula decreases then they contract because of their gravitational force and then its temperature rises at very high level and in that temperature hydrogen atom makes helium by fusion reaction and because of the speed of hydrogen atom and also heat the nebula takes a spherical shape which we call star.

Now black hole formation -

= The gravitational force of stats are balanced by their heat.

And hydrogen acts as a fuel for it.

= and when its hydrogen finishes then with passage of time that star cools down and then its mass and density becomes 4 times greater then its original mass and density.

And then that star can't control its gravitational force and then a blast occurs which we call supernova.

And after this blast if any of the piece of that star which have more mass remains then it becomes a star which have mass and density of a critical level and we call this as Neutron star.

In this type of Neutron star because of its gravitational force then it starts contracting and after contracting it at a critical level then it becomes a body which have infinite density and mass and because of this infinte density and mass the space time bents inward there and then it doesn't be there and we call this as a black hole.

Its whole mass is focused at center which we call it

✳ central singularity point

And the boundary of black hole is called

✳ event horizon

And nothing can escape from here even light can't.

And here concept of time doesn't work.

=> According to theory of relativity if the object is near the black hole then the time slows down for it.

Types of black holes

1. Stellar mass black hole

~> It is the type of black hole formed because of contraction of a star which have mass about 3 times greater than the sun.

2. Super massive black holes

~> It is formed in center of any galaxy and have infinite mass and gravitational force and it has mass about 100000000 times that of sun.

3. Permordial or small black holes

~> They are formed because of the more heat at the center of a star and the mass of that star is less than that of our sun.

Physicist think that they formed with the beginning of universe

Now, we will discuss about what is wormhole.

actually there are 10 dimensions in our universe but we can see upto 3dimensions only.

lets take an example

suppose you are moving in. a car

if you are travelling straight then thats 1st dimension.

if you move left and right too thats 2nd dimension

if there is a mountain and you go through mountain then Thats 3rd dimension.

means.

0D means a point

1D means having length

2D means having length and breadth too

and.

3D means having length, breadth and height.

but there is also type of length which we can't see thats the length of time.

thats called four dimensional space time.

now come to the topic.

as we know nothing is totally smooth in this universe means all the things are rough means there will be hole in everything.

and we know time is also a physical quantity .

means time have also some holes

that holes called wormhole.

Actually they destroy themselves because of their heat and energy

and if any object travel through wormhole they can go in past.

but they are too small even then quark and bosons.

and if any one will do time travel to past then there will be the situation called

(virodhawas)paradox

means

suppose you travelled in past and

you killed yourself.

but you died in past so how can you be in present.

and who killed you because you died in past.

thats called (virodhawas) paradox

worm hole connects black hole to white hole (this is another hypothesis on worm hole)

white hole is also a celestial body which throw out all the objects inside it