Why does the principle of conservation of angular momentum makes it very difficult to fall into a black hole?

Question

I'm so confused, can anyone explain this to me?

Answer 1

Black holes are, in general, very small (compared to astronomical distances).  Very rarely would an object fall directly into it.

Gravity would accelerate you as long as you are approaching the black hole.  However, if you miss and get passed it, the same gravity will slow you down, but only at the same rate that it accelerated you on the way in.

In order to be captured and kept in orbit around a black hole, is for you to lose energy.  One way to do that is to emit energy in the form of gravitational waves.  And that is a very slow process (unless you are very close to the event horizon, in which case other effects will have killed you by then).

So, if you draw a 2-dimension path of your encounter, with the black hole at the centre, you will see that the line joining the black hole and you would move faster and faster as you get closer (the angle at the centre would change faster).  However, the length of the line would get shorter and shorter.

The product of the two (rate of change of angle TIMES the distance) would represent your angular momentum.

As you pass the point of closest approach, the distance gets bigger AND the rate of change of the angle diminishes.  The product must remain the same: therefore, you will continue to move away from the black hole in a path that is similar (but reversed) to the one you came in.

Answer 2

Well, for one thing they may not exist

http://www.jamesphogan.com/bb/bulletin.p...

Actually there is not even a theoretical basis for their possible existence, let alone one that is testable or provable

http://www.sjcrothers.plasmaresources.co...

Answer 3

Whatever lateral speed you had prior to being pulled into a black hole would remain, and possibly make you "miss" the black hole because of its small size.  For something the mass of the sun, the event horizon will only be a few miles across, and missing it would just send you on a hyperbolic trajectory back away from the black hole.  If the black hole had an accretion disk, however, you'd most likely hit that and the friction would slow you down enough to pull you in (after vaporizing you).

Any gravitational object you enounter in space, if you do not directly hit it, you will eventually fall back away from it the same speed that you fell toward it.  Even to get into orbit around something, you need to slow down somehow.