system
Given the following post, respond as if you're commenting on Reddit:
human
Considering a supernova can lead to the creation of new stars is it not possible that if it was a big bang which created our universe, this event could have been a common supernova on a scale which we are just too small to understand in a universe that is much bigger than we expect?
gpt
A supernova is an explosion: it is a star (or stellar remnants like neutron stars or white dwarfs) which explodes and sends material traveling outward through space. It has a meaningful center from which the explosion originated. It creates star formation by adding material to the interstellar medium (the gas & dust between stars) and, crucially, by disturbing and stirring up that interstellar medium.

The Big Bang was not an explosion. It did not send already-extant matter traveling outward in a radial direction. It was a simultaneous expansion of space itself. It did not have a center-- the whole of space started enlarging. Imagine an infinite rectangular grid of points, each spaced 1 millimeter apart. Now increase that distance to a centimeter, now to a meter, now to a kilometer. No matter where you are, you will see all other points getting farther away from you, but this does not mean that you are uniquely at the center of the event--it's happening everywhere.

The extremely rapid expansion of space in the early moments of the universe meant that the mass-energy in the universe became less dense very rapidly, so that it could cool down and form things like protons (also known as hydrogen-1 nuclei), which, because the universe was still quite dense and hot by our human standards, could undergo some nuclear fusion and create some helium, the second-lightest element, and trace amounts of lithium. The universe's visible matter (i.e., not dark matter) was composed almost entirely of hydrogen and helium after this fusion ended when the universe was 20 minutes old or so.

Over time, the universe became cool and low-density enough that it was transparent. This is when the photons that hat been bouncing around in the dense hot opaque primordial plasma soup were able to stream freely in all directions. This is known as the "surface of last scattering" and is what we see as the redshifted Cosmic Microwave Background. It's by far the most important observational tool for understanding the early history of the universe, and it demonstrates that the universe was much hotter and denser in the past than it is now.

After the universe cooled further, the gas could start gravitationally clumping up and forming stars.

The universe may be infinite or it may be "finite but unbounded", like old arcade games where you can go off the left side of the screen and come back on the right side. Either way it's extremely large, so large (and expanding so rapidly) that physical material from an explosion can never travel all the way across the universe.