system
Given the following post, respond as if you're commenting on Reddit:
human
How fast does a star collapse?

Obviously, it takes billions of years to get to that point, but once the threshold is crossed, the tipping point, how fast is the process of collapse and explosion?
gpt
In the case of the formation of a neutron star, the core collapses in mere seconds (or event less), while the outer parts will enter free fall and bounce back so that the actual explosion happens minutes/hours later. That's because the shock wave is regulated not only by the gravitational energy released during the fall, but also by all the nuclear reactions that ensue and hydrodynamical instabilities that develop.

Note that the neutrinos emitted during a supernova escape earlier that the light of the explosion, since they do not interact very much with the outer shells of the star and can go straight through. You will "see" the explosion once the shock wave reaches the surface of the star and disrupts it.