Locating Parallel Realities

Our universe seems like a vast, endless ocean. As time passes by, its horizons keep getting bigger and bigger. As of now our observable universe is 93 billion light years in diameter and an estimated 14 billion years old. Since time has progressed, our perspective of the scale of the universe has broadened. For the western world which lived in utter ignorance well up until medieval times, the earth was the universe’s centre. After a while, hesitantly though, the heliocentric model was accepted. Then we widened our gaze and came to know that our solar system was just a small speck on the edge of the enormous Milky Way galaxy. Furthermore expanding our horizons, we came to know that other galaxies exist too and not only were some of them bigger in size than ours, there were millions of them! And as of now billions! So do our horizons close at the boundaries of our universe which is already enormous beyond measure, or does anything exist at all beyond the boundaries of our universe? That is a great new idea that cosmologists and physicists are dealing with today. A hypothetical world originated from the principles of quantum mechanics, from the amount of various probabilities and from the possible infiniteness of space-time, this world is the multiverse or parallel universes!

The idea of alternate realities existed in theories of quantum mechanics since the 1920’s but it came to the forefront in the form of multiple worlds after a Princeton graduate Hugh Everett invented his theory of ‘Many Worlds’. According to Everett, our universe is constantly splitting with every possible scenario that springs up here and each of these splits form their own separate universe. Let us take a simple event for example. Suppose in this world, I am a BTS ARMY, but in a parallel world maybe I am not(although I highly doubt that). This is just a simple example but the magnitude of the alternate possibilities is much larger.

Quantum mechanics is based on two important experiments/theories: one is Heisenberg’s Uncertainty Principle and the other is a thought experiment called Schrödinger’s cat.

Heisenberg’s Uncertainty Principle basically states that one cannot determine the velocity and position of an object together at any given space or time. This sprang up from the wave-particle duality of objects. We know that every object acts like a particle in space but we rarely notice how they behave as a wave in time. The wavelength that is length between the two wave crests is determined by the momentum of an object. The larger the object, the more the momentum because momentum equals mass times velocity (p=mv; p=momentum, m=mass, v=velocity) as stated by the second law of motion. The more the momentum, the shorter the wavelength. Even the wavelength of a tennis ball can be somewhat of a trillionth of a millimetre, so other everyday objects go unnoticed even if they emit wavelengths. But this phenomenon can actually be observed in really small objects like: electrons.

There is a popular slit experiment where two slits are opened in a wall that is placed in front of a screen. Electrons are shot at the screen and they take either of the two paths in the form of slits and get collected on the screen. But if observed well, we will see that they form a sort of pattern on the screen. A quite precise number of electrons are collected on either patch with a precise gap between them. That is because when the electron took the path, it was acting as a particle but before that as a wave it had travelled both ways. This shows the wave-particle duality of objects. Hence, this proves that every object has not one, but multiple histories! A particle could be in an infinite number of places at any given time in the universe and we will never know exactly where because of the uncertainty principle.

Our view regarding multiple histories was strengthened by a thought experiment by Erwin Shcrödinger known as Schrödinger’s cat. In this experiment, he imagined a cat to be kept inside a box for an hour with a device that had a 50% chance of killing it within the next hour. So when the box was opened after an hour the cat would have been either alive or dead. But he thought that before the box was opened the cat was both alive and dead! So the cat was destined to be dead somewhere and alive someplace else. Schrödinger however didn’t much like the dramatic effect of the theory and instead shifted his focus to other studies abandoning the study he actually helped invent.

Now here we have it: there are many possibilities for any particular event in the universe and they are realised in some alternate universes by our alternate realities. But what will those universes look like? Suppose there is a drastic difference in a law of physics in our universe and the other universe, how will life there play out? Surely we cannot imagine how exotic those life-forms who are impersonating our alternate realities look like. Now can we ever travel to those universes? And how are we to survive there given that we do land up in one them because of differences in biological, chemical or physical laws?

We can imagine these changes through certain ways. Here in our universe the colours we see are due to the way in which atoms reflect light. Maybe in a parallel universe atoms reflect light in different ways. A tree can be orange and a human can be green. There can also be differences in the dimensions of space-time. Our universe consists of four dimensions according to Einstein’s Theory of Relativity; three space dimensions and one time dimension. But if there are more dimensions in those parallel universes? How are we to fit our three dimensional bodies there and how are we to perceive them? One thing can be that since even imagining more dimensions is so straining for our imagination so maybe even if we are present in those multiple dimensions maybe we will not be aware of them at all! Our perception may be limited to how our mind has always perceived its physical surroundings.

Another factor that could be baffling from our point of view is how time may flow in alternate universes. In our universe, time always rushes forward which is governed by the thermodynamic arrow of time which states that the universe always progresses to a more disordered state as time runs forward. In our universe when a vase falls down on the ground it breaks into pieces; thus disorder. But maybe in an alternate universe, those broken pieces come together to form a cup; that is order from disorder. Also it can happen so that we can run in any time direction as per our will! Here we don’t have the independence to run through time like we have through space but maybe it is so in an alternate dimension.

Now what about travelling to these bizarre places? If we dream of travelling at the speed of light, it will not be possible within one human lifespan. So what can travel faster than light? Well we do not necessarily have to travel faster than light because general relativity says that we can in a way bend space-time! So if we bend the fabric of space-time that holds our multiverse, maybe we can travel to these universes within seconds! But that is surely baffling for now isn’t it? Because here we won’t only travel through space but also through time. Too much to take in right?

Well we do not know for now who knows whether a multiverse exists or not. It is purely hypothetical for now but it can anyday become a reality. It is a sort of place where we can seek comfort in the thought that at least somewhere all our desires are fulfilled but also it scares us that somewhere all our fears come true. Maybe that is why we dream, that is why we are scared and that is why we live differently here. It is upto us how we want to have this universe for ourselves: a place of fear and insecurities or a place where we seek for knowledge and find happiness.

“Absence of evidence is not the evidence of absence” — Carl Sagan