According to the theory of general relativity, once an object crosses the event horizon of a black hole, it is believed to be unable to escape and is destined to move towards the singularity at the center. From an external observer's perspective, the object appears to slow down as it approaches the event horizon, eventually freezing in time. However, from the perspective of the falling object, it crosses the event horizon without noticing anything particularly dramatic.
The time it takes for an object to cross the event horizon of a black hole, as measured by an external observer, depends on several factors, including the mass of the black hole and the velocity of the object. For a non-rotating, non-charged black hole (known as a Schwarzschild black hole), the time it takes for an object to cross the event horizon is generally finite.
In the case of a non-rotating black hole, the time it takes for an object to cross the event horizon is related to the mass of the black hole. This time is typically proportional to the mass of the black hole, with larger black holes taking longer to cross. However, it's important to note that this time becomes infinitely long as the black hole approaches its maximum possible mass (known as the Schwarzschild limit), which is purely a theoretical concept.
It's worth mentioning that the concept of time near a black hole is complex due to the strong gravitational effects. The specific calculations and predictions require solving the equations of general relativity, which can be highly intricate. Nonetheless, from an external observer's perspective, the object crossing the event horizon appears to take a finite amount of time, although it may seem to slow down significantly as it approaches the black hole.