Parallel universes or as they are now more commonly known, the multiverse, have been around as a concept almost as long as science fiction became a genre. Our visible universe is three-dimensional with the fourth dimension generally accepted as time. We know that the theories of Isaac Newton about the mechanics of the stars and planets work pretty well on a macroscopic level. But, when we study the universe on the scale of fundamental particles, the laws do not work. Instead, we have to use quantum physics to help explain what might be going on. You may notice my use of non-exact terms means that we still have a great deal we do not know about this subject.
However, with the advent of quantum physics, the multiverse moved from science fiction to science possibility. We need to get one thing straight; quantum theory is strange, really strange. It offers scenarios which fly in the face of those who were happy with the mechanics of a Newtonian universe. For example, we have Schrodinger’s cat sitting in a box both alive and dead at the same time and will remain so until we observe it. We cannot know whether a particle is and how fast it is moving at the same time. The very action of observing something may cause it to change. A particle of light called a quanta can be both a particle and a wave depending on what is happening to it. Look up the Double-Slit Experiment to find out more. Instantaneous travel becomes a theoretical concept. And it goes on. So, the quantum universe is very weird.
Therefore, when it comes to discussing whether there is one universe or many, we need to use quantum physics to help us. If there was a parallel universe to ours, Schrodinger’s poor cat might be alive in one universe and dead in the other. The act of opening one of the boxes would then tell us which universe we were in. I told you this was going to be weird.
We now come to another concept and those of you who are fans of “The Big Bang Theory” (the TV show, not the beginning of the universe), will know that Sheldon was for a time, a big fan of string theory. It postulates a form of multiple universes by saying that there is one universe but that there are 10 dimensions to it. We live in a bit of it called the three-dimension part. So, there is more than just our reality.
String theory is a mathematical concept. However, in certain areas, it does make sense and seems to stand up to some scrutiny. When it comes to the Big Bang, not the TV show this time, the theory states that this occurred because two parts of the 10-dimensional universe collided. Dark energy, like dark matter, has to exist or our universe could not function as it does. But we cannot detect either of them, only their effects. But string theory believes that dark energy might exist through one universe exerting a force on another universe. If you can come up with an experiment to prove all this, I should think you would be in line for the Nobel Prize in Physics.
John Pullen 