i haven't yet got this concept. i have read about the time "freezing" near a BH , but am not clear. can u please explain what actually happens? why does the time stop? i also want to know one thing-- when, supposing 'A' enters the event horizon he moves slowly towards the singularity because of the time. but isen't gravity stronger? so shoulden't he move faster? oh one more thing, is there any other way of detecting a black hole other than the movement of stars?