How math tells us that something exists in outer space ?

Question

I was watching a video about black holes, and when they mentioned that Einstein proved black holes exist with maths, it hit me.
I’ve never asked myself that question, how do numbers tell you that something exist in outer space and what to expect from it? especially things that we never knew they existed in the first place (exp black/white holes) ?

In: 407

Answer 1

Was it Dirac who had that antimatter solution from his equations about particles?