How do scientists/physicist know that there is a singularity inside a black hole?

Question

First of all how do they know that black holes exist when they cant be seen thru a telescope since there is no light near them?

And how can they come up with the idea of there being a singularity (physics out of control) in the center of a black hole?

Please dont complicate things for me.

Answer 1

Black holes, may not exist, however there certainly are very very dense and very very dark objects in the Universe that can be "observed" by the motions of neighbouring stars.

No one really knows what is inside a black hole. Singularity is a mathematical concept and doesn't really have a physical meaning.

Answer 2

Since you cannot literally see a black hole, thus the name, you cannot directly prove their existence.  

Once we get that out of the way, we can attempt to explain the singularity.  Basically, all the mass is concentrated on a single point.  Since there is a high mass, you would use general relativity to explain the physics.  And you would use quantum mechanics to explain something very small.  The two theories are incompatible, so physics "breaks down" at a singularity.

Now for the black hole part.  Light cannot escape a black hole.  This would mean that it would require a certain amount of mass within a certain volume.  The force of gravity is so strong, that the mass is not able to support itself, and it collapses to a singularity.  Since we cannot directly observe a black hole, and no light can escape past the event horizon, we do not know what actually happens in a black hole.  

So if we can't see them, how do we know they are there?  We can see their effect on the surrounding environment.  Galaxies spinning and being held together needs more mass than what is already present.  So far, a black hole is the best answer for this.  There are other reasons for belief in the existence of black holes, but that would be far more than you ever wanted to know.  Hope this sheds some light on your question.

Answer 3

They don't "know".  it is just a guess.

People smarter than you and me set around dreaming these things up. They come up with THEORIES, guesses that seem to explain things.  

There is a THEORY that there is a black hole at the center of a galaxy. The CAN see how galaxies look, and this theory explains why galaxies look that way, IF there was a black hole inside them.  

But what is a black hole?  Scientists have made another theory that for the black hole to work the way they think it does, then there must be a singularity inside of it.

But what is a singularlity?  Scientists have another theory . . . .

It is ALL just guesses, theories, that cannot be proven, but just as importantly they cannot be DISPROVEN.  So your theory is as good as mine.

Until somebody actually builds a space ship and goes to the center of the galaxy (and gets caught in the black hole . . . .) we'll never know for sure just exactly what is going on.

Answer 4

It is predicted by the math of mass vs escape velocity.  If an object is massive enough its escape velocity is equal to the speed of light.

There are stars known to exist that are massive enough that when they go nova, what is left is massive enough to have that much mass.

Many nova remnants are known that fit the profile for a Black Hole.

Physics predicts phenomena that will occur around and outside the Event Horizon of a Black Hole.  These phenomena are observed.  Therefore, if it ain't a Black Hole, as predicted,  something even weirder is going on.