Physicists have suggested that our entire universe may be the other side of a black hole. Theories of this sort are highly speculative and subject to replacement by another theory in a short while; but the idea is that every black hole has a white hole and a whole universe on the other side. Let me try to explain. Black holes are mathematically predicted to occur in our universe and several potential ones have been identified in our universe, including one at the center of our galaxy. Black holes are usually caused by the collapse of a large star such that large amounts of mass are compressed into a small space resulting in a huge gravitational force. As more and more mass falls into the center of the black hole the gravitational force continues to increase to the point where it attracts everything around it including light. The entire black hole collapses into a single point of matter known as the singularity. At a certain point, close to the black hole, an event horizon forms. The event horizon is the point at which nothing escapes the gravity of the black hole and all mass and light is drawn in. Thus, the name black hole, they are dark because not even light escapes from them. They appear as a spherical orb of absolute darkness and are only detected by the gravitational lensing that they create as light passes between earth and a black hole. (See here for a more complete explanation of a black hole.)
So, if all of that mass, energy, and light is attracted into a black hole, where does it go? The latest theory is that on the other side of a black hole is a white hole. A white hole is a point, or singularity, from which immense amounts of light, mass, and energy spew. (See here for an explanation.) A singularity spewing massive amounts of light, mass, and energy sounds a lot like the Big Bang from which our universe sprang. Could it be that our entire universe is simply the other side of a very large black hole? That is what one of the latest theories suggests. In fact, it may be that on the other side of every black hole another universe exists that owes its beginning to a black hole, a white hole, and a Big Bang (see here for more).
I know, if you think about such things for too long it will either give you a headache or drive you insane trying to understand it all. Or, it could simply drive you to the point of believing that, behind it all, there must be a Creator God. As Sir Arthur Eddington once said, “Not only is the universe stranger than we imagine, it is stranger than we can imagine.” It is as if God were showing how mighty he is when he built this universe (and perhaps a few more universes) or maybe he was just being incredibly creative. The more we learn about our known universe, the more we realize that it is ultimately incomprehensible to our limited minds. The greatest minds in science are continually stumped by the complexities. The immense scale makes it incredibly difficult to even observe black holes and other interesting objects. If we could get close and experiment with a black hole, perhaps we could learn more; but the closest one to us is the one at the center of our own Milky Way Galaxy, approximately 25,000 light years away. Could it be that God made ultimate reality frustratingly out of our reach? Did he purposely make it so difficult to understand that the universe will always contain a great measure of mystery? Might it be that we truly need to live by faith and not by sight?