At what point in a star's collapse does the event horizon form?

Question

Does the event horizon form as soon as the stellar core's surface reaches the Schwatzchild radius?

If so, how could the core have time to contract into a singularity during the lifetime of the universe, given gravitational time dilation? Can there be any stellar black hole singularities?

Answer 1

You said: "from our reference frame ... a singularity could never form".

From our reference frame, as soon as the event horizon forms, everything below it disappears from our observation.  We can only detect the mass, spin, and electric charge.  It's meaningless to say that the singularity could never form, because it is outside  our observation.  We can, however, figure out what happens from the reference frame of a particle inside the event horizon -- the only proper time frame for such things.  And from the viewpoint of such a particle, the singular forms very quickly.

Answer 2

The point in the black hole's orbit in which gravity is able to pull light inward.

Answer 3

Immediately after it contracts into a singularity.

Answer 4

again the correct answer is....we do not know. anyone who tells you they know what a black hole is, or when the event horizon (slang term, hollywood term lol) takes shape does not know what they are talking about. plain and simple. the knowledge available on this cosmic phenomenon just does not yet exist on the earth. we know almost nothing, if not nothing, about this phenomenon.

LOOK TO GLAST!

Answer 5

Your question is rather complex but it can be answered in a somewhat intuitive manner:

As the star begins to contract, it's mass becomes increasingly concentrated into an ever smaller region of space.

The effects of gravity become increasingly pronounced.

Soon, the gravity becomes so intense that a beam of light directed out into space will fall back to the ground, following the same parabolic path as an earthly projectile.

At a point very near the end of the body's existence as a star, light must be directed perpendicular to the ground in order for it to escape.

When the collapsing star passes its "Schwartzschild radius", it vanishes from view because its escape velocity has exceeded the speed of light.

I would imagine many other variables come into play that also add to the effect.

However, the overall point in which this spectacular event occurs is based upon a set pattern of variables.