system
Given the following post, respond as if you're commenting on Reddit:
human
[Star Trek] By what mechanism does red matter create black holes?
gpt
Believe it or not, red matter doesn't create black holes. What it actually does is access a different layer of space. 

Subspace was discovered (or, likely, rediscovered) by the Vulcans a few hundred years before First Contact. It was accidental, but led to a huge boost in technological development, especially in the areas of propulsion and communication. The Vulcans discovered that there are layers to space, not occupying the same space at the same time, but overlapped. It's a part of the grand space-time continuum. As we've seen with subspace communication, instantaneous across great distances, different layers of subspace have different laws. That's one layer of subspace, but there are many more. 

Red matter is a highly unstable substance, created from decalithium. It's related to trilithium, which was in the weapon Dr. Soran used to destroy the Amargosa star. Instead of acting as a nuclear inhibitor, however, decalithium interferes with the fabric of space-time. The Romulan Captain Nero of the mining vessel Narada discovered the element while on a mining mission for the Romulan Star Empire. He sent back a report on his scans, and the Romulans realized the power of the element, however they lacked the technology to develop it. The Romulans realized that they could harness a layer of subspace with super-intense gravity (and thus a totally different relationship with time) with red matter. Because of the anomalous supernova of the Hobus star, it had to be rushed to the Vulcans, who weaponized it for the Romulans. 

Ambassador Spock was able to use the red matter to pull the supernova into the layer of high-gravity subspace, saving countless worlds, though not in time to save Romulus and Remus. 

Ambassador Spock and the Narada disappeared into the subspace tear, but there was no evidence they were destroyed by the gravity or were pulled in. Because of the super-high gravity's effect on time, however, it's been theorized that they may have ended up in a different time.