what is the escape speed at the event horizon of a black hole
Event horizon
d p = ∫ 0 t 0 c a ( t ) d t . ( \ displaystyle d_ ( p ) = \ int _ ( 0 ) ^ ( t_ ( 0 ) ) ( \ frac ( c ) ( a ( t ) ) ) dt \ . )
d p = ∫ 0 t 0 c a ( t ) d t . ( \ displaystyle d_ ( p ) = \ int _ ( 0 ) ^ ( t_ ( 0 ) ) ( \ frac ( c ) ( a ( t ) ) ) dt \ . )