Photons do have momentum.
As photons go into a lower energy state their frequency changes: E = h*f.
So when light hits the solar sail of the science fiction spacecraft, the light 'changes colour' because when it loses energy it must lose frequency. The amount of light particles stay the same.
So yes, the only way to stop light is to change its direction or to decreate it and use it's energy for something else. Otherwise light moves in a straight line with speed c (through vacuum). Even when light is bend this is because the space-time light goes through is bend, while the photons still travel in a straight line.
Funny thing about light. Our percieved intensity of light depends on the amount of photons, not on their energy state. Their energy state merely depends for the colour. Do note that the higher the frequency of the photons this does matter in reactions and other physical processe. A gamma particle, a photon with enormous energy and thus very very high frequency 'damages' (actually ionizes) matter. So because the atoms in our body degrade, breaking down molecular binds, our body is damaged. Thus gamma radiation can be lethal. Apperently one of the worst ways to die. Note, the person doesn't die from cancer. This is the effect of less radiation over a long term. When exposed to extreme doses of radiation over lenghts of time the body just falls apart on a molecular level in a matter of hours.
A black hole is just a very very mass-intense object. In a sense it is very simple in that it is a very heavy marble. A black hole doesn't have to be big in size, though some are also enormous in size.
The strange thing is the effect of the extreme gravity. In the center of the earth there is a radius of 9 mm where light would not be able to escape. In a black hole this radius lies outside the radius of the physical object. If the earth would be reduced to an object with a radius of less than 9 mm, earth would also be a black hole. But gravity is a relatively weak force so this does not happen.
Let me explain it through this.
The earth is relatively massive. Because of it's mass it can pull on other bodies of mass, for example you and me. Lets say we are in a garden with a nice ponds. In autumn there will be leaves floating on the surface of the water.
Gravity is so extremely weak that surface tension of the water prevents the whole earth from pulling the leaf through; the whole earth with all its mass! And if you take your finger and touch the water you can barely feel it takes some force to break the surface of the water.
Same with a magnet. Eventhough a magnet is the fraction of the mass of the earth it can easily defeat gravity.
In a black hole gravity does dominate. Electrons are pulled inside the nucleus of an atom. Your theories of quantum mechanics, that make our computer screens and tvs work, just ignore gravity because it's influence is irrelevant. But not in a black hole. Your theories do not apply.
Even worse, gravity affects space-time. A black hole is, in a sense, cut off from our space-time. There are different ways of putting this into words since this is too bizarre from our language. You could say that the space-time of a black hole is folded into itself. You could say that space-time falls inside a black hole faster than the speed of light. You could say that time stands still inside a black hole. No event inside a black hole can affect anything outside a black hole. There are many more very strange things. And this is why physicists are so interested in them.
Now something called Hawking radiation has been discovered by Stephen Hawking. Because of virtual particles(don't ask) particles can escape a black hole through 'quantum tunneling' (don't ask). So radiation can escape a black hole. This is one of the first steps into quantum gravity, as I explained earlier a field that is still largely empty. The theory may even not hold and be refuted within some years.
But the theory does say that a black hole slowly evaporates.
an infinite number or any thing infinite would be something uncountable.
That's not very large for a small child.
circles can be infinite, right?
Of course not. Otherwise it would take infinite time to even draw one. The surface of the earth is finite, but it doesn't have any barriers. Space can be the same shape. It doesn't need a barrier to end. A 3d 'surface' on a 4d 'body'.
As it stands now the size of know space is limited by how far we can observe. So people always talk about the edge of the observable universe. Beyond that, light/information from those areas hasn't had enough time to reach us yet. So in a sense they aren't yet part of our reality.
Topic: What have you got to lose?