I have only taken one college level physics class (Conceptual Physics), but my teacher lectured on a subject that has been stuck in my mind since (5 years). If matter/energy cannot be created nor destroyed, then nothing can exist. The idea didn’t fully sink in until after the course was over, but once it did, I have been like WTF? For 5 years. I completely get the law of conservation. If you were to destroy matter, where would it go? If you were to create matter, from where would it come? But, my professor was also (I believe) correct in the fact that this physical reality in which we live is a complete impossibility, as there is matter in it, and matter cannot be created. I have talked to some people about this, and most just say, “Well, the matter has just always existed” I find that somewhat impossible. Something doesn’t just come from nothing for one, and how could something just have always existed with no source? I really appreciate any input on this subject.