As a matter of fact, I recently learnt that as an object is approaching a black hole, to an outside observer the object seems to be getting slower and slower and will cross the event horizon after an infinite amount of time ie will not cross the horizon. Now this matter which the observer was observing seems to be stopped at the boundary outside the event horizon, thus forming the accretion disk. But since the object is actually inside the black hole since it has crossed the event horizon from his viewpoint. Thus we conclude that the object is actually inside the black hole but to an outside observer it’s not inside.
Let me put up a thought experiment.
Imagine me and my good old friend are somewhere in space nearby a recently formed black hole. It has no apparent accretion disk but we know it’s somewhere in a specific direction. Now my friend volunteers to go into the black hole. According to calculations the time taken for him to cross the event horizon be some interval “t”. Now he goes. After “t” interval my friend is inside the black hole and sadly has been reduced to ..... . I know he must have crossed the event horizon but I can still see him outside of it. Now I also go towards the black hole. Just before I reach the horizon I can still see my friend outside but in reality he is already inside. And then I cross the horizon. Just imagine for a split second that I can see inside the black hole. What will I see ?
I will see my friend and myself. And if any more matter comes from outside I can see it. But from an outside observer, my friend and me are still before the event horizon thus forming an accretion disk. But since we are actually inside the black hole. Then the accretion disk must be an illusion. Cause how can me and my friend be both inside and outside the black hole.
Now please tell me if I m correct in my reasoning regarding it. I have been pulling my brains over and over again, running the experiment several times and conclusion is this only that the accretion disk is an illusion.
Hopefully, you all may give insights regarding this question.