Can we uses the energy of black holes to summon a demons. space* time*life
Great question but I doubt it. Black holes form in space when stars, much larger than our Sun, collapse on themselves. They concentrate large amounts of matter in a very small space. They are so dense that the gravity they exert is such that not even light can travel through them.
The creation of black holes confirm theories that our universe might not be 4 dimensional (3 space plus 1 time dimensions), but could possibly host other dimensions. However could you summon demons or perform rituals utiluzing black holes? I would doubt it. In the same way that the theory of relativity or of quantum mechanics revolutionized our way of thinking, discovering the existence of extra dimensions would be a major new milestone in our understanding of the Universe. But I am uncertain if it could be used magically for creating a demonic portal.
Many will start speculating about using these extra dimensions for magic but also space and time travel, or as a source of clean energy. But who knows you might compare it to the discovery of magnetism by the Phoenicians who could not foresee that electricity and magnetism would completely reshape modern life… The theory of black holes for magic would make a great si-fi movie or book.