The last three sentences are not quite accurate. It's not necessarily that nothing existed before the the big bang. It's a singularity event where mathematically we can simply not know what existed at/beforehand that moment. It is somewhat comparable with the event horizon of a black hole.

There is something happening/existing, otherwise a black hole would not be able to occupy space or affect light. We simply do not have the ability currently to understand what that is.

By definition, that is not nothing. It is a that we cannot know/understand it, at that moment. Notably, a lack of evidence is not evidence of nothing.

[–] RedditWanderer 5 points 2 weeks ago

He means the matter we know as galaxies today.

Our current theory implies that our space we know and love (bound by our time, spacetime) expanded at that moment. We know we shouldn't be seeing older galaxies that look younger than others we know to be young. That's what's implied by these findings at least - they could still be explained by other things we have yet to discover, because we haven't finished processing this data.

The title is just for the clicks.

[–] mumblerfish 3 points 2 weeks ago

Not the event horizon of a black hole, but the singularity at the center. The event horizon is only a singularity in certain coordinate systems, but you can select coordinates that are smooth there. The black hole singularity is more comparable to big bang, in the sense that it is an indication of missing physics.