When you fell inside of a black hole ? what's inside is ?

well , nobody knows at the moment. This is because no one has ever gone in, or observed the inside of a black hole. And if anyone did go in, they would definitely NOT be able to come back out to tell their tale. Currently, mathematical predictions and theories have come up with what happens close and outside the black hole, but only very vague ideas about what goes on inside.

A black hole is a place where the laws of physics as we know them break down. Einstein taught us that gravity warps space itself, causing it to curve. So given a dense enough object, space-time can become so warped that it twists in on itself, burrowing a hole through the very fabric of reality.

You've managed to travel tens of thousands of light-years beyond the solar system. Bravely facing the depths of the great interstellar voids, you've witnessed some of the most achingly beautiful and outrageously powerful events in the universe, from the births of new solar systems to the cataclysmic deaths of massive stars. And now for your swan song, you're going big: you're about to take a dip into the inky blackness of a giant black hole .

The point where light can just escape is called the event horizon, and after you pass this point you are inside the black hole and can't get out. It is possible however to enter a black hole and not die.

As we near the black hole, there is something called the ‘event horizon’, which is better known as the point of no return. The actual meaning of an event horizon where the escape speed exceeds the speed of light: you’d have to be going faster than light (which is impossible for any bit of matter) to escape the black hole’s gravity.

The event horizon isn't a real, physical boundary. It's not a membrane or a surface. It's simply defined as a particular distance from the singularity, the distance where if you fall below this threshold, you can't get out. You know, no big deal.

This is the distance from the singularity where the gravitational pull is so extreme that nothing, not even light itself, can escape the black hole's clutches. If you were to fall below this boundary and decided you had enough of this black hole exploration business, then too bad. As hard as you fired your rockets, would find yourself no farther from the singularity. You're trapped. Doomed.

But not instantly. You have a few moments to enjoy the experience before you meet your inevitable demise, if "enjoy" is the right word. How long it takes to reach the singularity depends on the mass of the black hole. For a small black hole (a few times the mass of the sun counts as "small") you can't even blink an eye. For a giant on, at least a million times bigger than our sun, you have a handful of heartbeats to experience this mysterious corner of the universe.

But hit the singularity you must. You don't get a choice. Within the event horizon, nothing can stay still. You are forever compelled to move. And the singularity lies in all your possible futures.

Outside the black hole's event horizon, you can move in any direction in space you please. Up? Left? A little bit of both? Neither? The choice is yours. But no matter where you do (or don't) go in space, you must always travel into your future. You simply can't escape it.

Inside the event horizon of a black hole, this common-sense understanding breaks down. Here, a single point — the singularity — lies in your future. You simply must travel toward the singularity. Turn left, turn up, turn around, it doesn't matter — the singularity always remains in front of you. And you will hit that singularity in a finite amount of time.

Clock's ticking.

Inside the event horizon is where physics goes crazy. This area is where Einstein’s Laws of Relativity will cease working, and we may have to rely on quantum physics, an area not explored much. Calculations suggest that what the fabric of spacetime looks like inside a black hole depends on that particular black hole’s history. It might be turbulent, twisted, or any other number of things. One thing’s for sure, though: the tidal forces would kill you.

Indeed, light cannot escape from within a black hole, but the matter falling into a black hole can get pretty hot before it falls in. This heating is due to the fact that matter accelerates near black holes. As a result, matter emits lots of light and other radiation as it falls into a black hole.

According to most theories, within a black hole there’s something called a singularity. A singularity is what all the matter in a black hole gets crushed into. Some people talk about it as a point of infinite density at the center of the black hole, but that’s probably wrong. True, it’s what classical physics tells us is there, but the singularity is also where classical physics breaks down, so we shouldn’t trust what it says here.

The black hole itself is a singularity, a point of infinite density. But you can't see the singularity itself; it's shrouded by the event horizon, what we generally and wisely consider the "surface" of the black hole. To go farther, you must first pierce that veil.

But that mathematical situation won’t exist in reality. Others say that the singularity is actually a whole surface inside the event horizon. We just don’t know. It could be that, in real black holes, singularities don’t even exist.

Event Horizon

A black holes' event horizon is its outermost boundary. This is the point at which the gravitational force precisely overcomes light's ability to escape the black hole's pull. 

It is the literal point of no return - you cannot escape once you pass it. 

At least that was the traditional view. The venerable Professor Stephen Hawking, during his life, was adamant that the definition of a black hole should be changed. 

In his mind, he believed that event horizons, as they are traditionally understood, don't actually exist at all. They are, in fact, "apparent horizons" at the edge of black holes, where quantum mechanics goes crazy.

Here, like everywhere else, virtual particles pop in and out of existence causing the horizon to fluctuate, making it more of a flickering, growing and shrinking mess. 

These "apparent horizons" are also a point where quantum effects create streams of hot particles that radiate back out into the Universe - so-called Hawking's radiation. It is thought that this will eventually cause the black hole to radiate away all its mass and disappear. 

As light cannot escape once past the black holes' event horizon they can't actually be 'seen' in a traditional sense. We can, however, infer their existence from their effects on other bodies in space (like Suns and gas clouds) we can see. 

It might soon be possible to detect the boundary of the event horizon around the black hole - rather the Hawking's radiation emanating from it.

 IF You Fell Into A Black Hole

So long as it's a supermassive black hole you wouldn't feel anything you'd actually be in freefall (what Einstein once called his "happiest thought"). You'd exist and then inevitably you wouldn't, your mass added to the ever hungry bulk of the black hole.

For an observer, however, its a very different story.

As you approach the event horizon you will appear to immediately accelerate, stretch and distort obscenely. 

Interestingly you will appear to move in slow motion the closer you get to the horizon until you freeze (as if on pause). 

Now for the fun bit, as you remain there motionless you will also begin to stretch across the surface of the horizon and as you start to heat up, you would also appear to become redder and redder. You would then begin to slowly obliterate as you stretch across the curved space-time of the black hole. Time would appear to stop and the fire of Hawking's radiation will likely appear to engulf you. 

Finally, you'd be reduced to ash before your remains would appear to plunge into the absolute darkness of the black hole proper. 

A spectacular scene, to some gruesome, but one you would never see. 

For smaller black holes you undergo a process commonly termed "spaghettification". This is a very different, and somewhat more disturbing, story.

At the center of a black hole is something called a gravitational singularity, or singularity for short. This is where gravity and density are infinite and space-time extends into infinity.

This is the final destination for anything that strays too close to the black hole and disappears over the event horizon. 

The Closest Black Hole To Earth Is

The closest black holes yet discovered to Earth are several thousand light years away from us. At this distance, these black holes will have no discernable effect on our planet or its environment. 

To date, the nearest black hole, called V616 Monocerotosis, is 3,000 light years away and has a mass around 9-13 times that of our life-giving Sun. The next closest is Cygnus X-1 (about 6,000 light years away with a mass of 15 suns).

Next up is GRO J0422 + 32, which is actually one of the smallest yet 'discovered' and is roughly 7,800 light years away.

As far as we know the nearest supermassive black hole, Sgr A, to us sits in the middle of our home galaxy - The Milky Way. This monster is roughly 27,000 light years away from us. 

You can 'find' it in the approximate direction of the Sagittarius constellation. Its enormous gravitational pull is currently busy tearing nearby stars to pieces, adding their mass to its own.

Our galaxy's supermassive black hole is estimated to be several million times (approx 4.1 million times to be precise) the mass of our sun. But don't worry its enormous distance from us doesn't directly affect our solar system - at least yet. 

It is thought that in about 4 Billion years our galaxy will collide with our neighbor galaxy Andromeda. When this happens stars, and their respective black holes will be mixed together into a new blended galaxy. 

Stars will start to interfere with each other's orbits likely sending some into the waiting, and always hungry, jaws of the two supermassive black holes. This will likely ring the death knell for many stars, and their child planets. 

A Black Hole About To Die

The lifespan of a black hole varies depending on its mass. You can only really know by running quantum field theory calculations in strongly curved space to find out - which is complex, to say the least.

As a general rule mass loss from Hawking's radiation occurs at different rates relative to the 'size' of the black hole. Interestingly lower mass black holes lose their mass quicker than larger ones.

This is because the curvature they create in space is more intense around their events horizons. But even so, it takes a very, very long time indeed.

By way of example, it is estimated it would take 10^67 years for a black hole with the Sun's mass to completely evaporate. For the larger black holes in the Universe, it would take an unbelievable 10^100 years.

Universe of black hole

Even if we tried to count them we would never get the right answer as a large part of the Universe will be obscured from our view, forever. If such an attempt was made we would first need to limit our count to "our Universe" or what is more correctly called the "Observable Universe".

We can, however, make some educated guesses. 

Stellar-mass black holes form from the supernovae of massive stars. Our Milky Way alone contains around 100 Billion stars and roughly one in every thousand stars is big enough to create a black hole when it dies.

This should mean that there might be as many as 100 million stellar-scale black holes in our galaxy. But this number is increasing with every second that passes. 

New-stellar mass type black holes are thought to form once every second or so.

If we are talking about supermassive black holes these tend to lurk at the center of galaxies. In our local region of space, there are about 100 Billion supermassive black holes or thereabouts.