Black holes are fascinating astronomical objects that are formed from the remnants of massive stars. Their nature is described by the theory of general relativity, proposed by Albert Einstein. According to this theory, black holes are regions of spacetime where gravitational forces are so strong that nothing, not even light, can escape their gravitational pull.
Black holes are characterized by their mass, charge, and angular momentum. The most basic type is called a Schwarzschild black hole, which has mass but no charge or angular momentum. There are also charged black holes (Reissner-Nordström black holes) and rotating black holes (Kerr black holes), which possess additional properties.
As for the connection to other universes, this is a topic that goes beyond current scientific understanding. In mainstream physics, black holes are considered to be isolated entities in our universe. They do not serve as portals to other universes based on our current knowledge.
Detecting or measuring the presence of other universes, if they exist, is a challenging task. It would require evidence from theories that support the existence of multiple universes, such as certain formulations of string theory or the multiverse concept. However, these theories are highly speculative, and experimental verification is currently beyond our technological capabilities.
From outside a black hole, we can only observe its effects on the surrounding spacetime and matter. For example, we can study the gravitational influence of a black hole on nearby stars and gas, or observe the radiation emitted by matter falling into a black hole. These observations provide valuable information about the properties and behavior of black holes, but they do not directly allow us to peer inside or detect connections to other universes if they exist.