What if, every single time a choice is made, the universe splits into infinite probabilistic outcomes, allowing each choice to happen, but our consciousness resides in only one of these realities? Considering this theory means that an infinite amount of universes exist. This infinite is so large: purely beyond any level of our comprehension. This interpretation, classified as the many-worlds interpretation of quantum mechanics, assumes that each reality operates under the same laws of physics. It also presents the possibility that all of our actions are merely statistical actions, and are not deliberated by our consciousness and are not a result of free will. This is the theory I was taught, but was never satisfied with. I have always assumed there was only one such parallel universe, but as I delved into more research I found a model that makes our laws of physics purely subjective, makes us realize the almost impossibility of our existences, and reveals how little we really know about our world.
Our life on this planet is positioned upon stacks and stacks of seemingly pure coincidences. For example, it is by pure chance that the magnitude of the charge of an electron is the same as that of a proton, and it by pure chance that they have the masses that they do. It is by pure chance that the distance of earth from its parent star is what it is: if it were any different, there would be no liquid water on earth. These numbers that govern our existence, precise to many decimal points, seem to appear out of nowhere. Is this a sign that God exists? This is what many believed during the pre-Darwin era: that everything was created by design. For example, in 1802, Reverend William Paley analogized that everything in existence is like a watch: when you buy a watch, it is evident that the watch did not appear out of nowhere, but that it was made by someone you presently do not see. Same was the thinking behind anything else in existence. But, as science and time advanced, less theological approaches were presented to what is now known as the “fine-tuning problem.”
How is it possible that the conditions were just so perfect, so void of mistakes, so fine-tuned, that allowed us to be alive? How did all this just appear? Well, if you take into account the billions of other planets in this universe, the problem can be solved if we just say that Earth won the existence lottery. But this presents a problem. This inter-universal interpretation assumes that there can ever only be one set of laws of physics. But aren’t these laws also a mere coincidence? Current physics suggests that only one set of such laws govern our cosmos. What if there are multiple universes, different only by the laws that govern them? This interpretation, called the anthropic selection effect, suggests our universe was a result of the fine-tuning of many other universes. In other words, billions of universes exists with different physics, making the physics which makes Earth possible more probable than coincidental. Earth, therefore, is a probability within a probability.
Currently, there is no evidence to either prove or disprove the interpretation of anthropic selection. The existence of the positron was theorized by mathematics long before it was discovered. So, who knows what can happen. The problem with physics is that it adheres too closely to established physical constants (ie gravitational constant, Planck’s constant) and works only through predictability. To prove this theory of multiple universes, physicists must examine the physics of other universes: a plunge into the unknown I doubt they would be willing to take. Additionally, there could also exist an undiscovered constant or formula that could determine that the creation of earth was, in fact, a very likely occurrence. So, for now, the reason why our existences are so fine-tuned evades us. This also reveals how little we know about physics, and the amazing this is, we will never know if we discovered it all. Therefore, there is always going to be a question left unanswered, and there will always be the possibility of something so great and incredible just a few equations away.
Personally, my feelings toward this interpretation are ambivalent. It seems like a quick fix to a very big question, and I believe that there is a better explanation to it. But what appeals to me about it is that it forces us to consider our lives in the unknown and the potential possibility that our laws of physics lack the dominance and quantization that would like to believe it has. Sometimes a reminder like this is what we need as a shot to our egos.
So, what do you think about parallel universes?
Disclaimer: Although I did my research from credible sources, I am not a scientist and I know fairly little about this area of study, so please take it all with a grain of salt.