You remember Alice, Alice from the famous story Alice in Wonderland written by Lewis Carroll where she fell through a rabbit whole and discovered a world of anthropomorphic creatures. Perhaps it was the most enjoyable explanation of parallel universe where Alice found some buddies but in a new shape!
Parallel universe is the concepts of existence of parallel worlds where same things may exist with slide differences between them. From the early 1920s, physicists were trying to find out a new world. Skeptics tried to speculate these hidden worlds would be full with ghosts and spirits. But scientists were not on to that anymore. Rather they were trying to solve an age-old problem. Trying to find out the real nature and exact location of an electron, scientist first came with a great disappointment. They could not manage to find out the exact location of the electron. Instead they came up with a brand new idea.
The idea is called string field theory. Physicists observed that, electrons don’t exist in one universe and there is a greater possibility that they might exist in another universe simultaneously! Strange, isn’t it? But that was the old case. The real deal came in to the limelight when a young PhD candidate from Princeton University postulated that parallel worlds do exist because there is a scientific explanation. His name was Hugh Everett III. Everett was a brilliant student; at that time he was allowed National Science Foundation fellowship and attending Princeton. He was a smart kid, used to read a lot of science fiction books and already had a degree in chemical engineering. He was also well versed in mathematics and photography. Hugh argued that there is another world where the laws of physics work differently. Actually he was trying to prove why quantum matter works abnormally. In quantum physics, laws of classical physics don’t fit appropriately. The phenomenon was also disputed years ago when Max Planck experimented with radiation. He also found unsatisfactory results and predicted that there may be another universe where the laws best fit.
In quantum physics, any matter can exist in many states. This property is called superposition. The sum of the total positions is called wave function. The postulation was supported by Danish renowned physicist Niels Bohr who with Werner Heisenberg developed some research papers. They also said, the real nature or attributes of quantum particles would be unknown. Everett accepted all the proposals but contradicted to this point. Everett asserted, in quantum mechanics there exist a whole different idea of matter existence. In quantum level any sort of matter can exist in two different states like in gaseous form or solid form. He argued if scientist tries to measure the dimension of an object, he may find out ambiguous results. He may measure the dimension of gas or the solid. But this can be only possible if there are two distinct universes where the subject resides simultaneously in two distinct formations. Only then two scientists from
two worlds will find out some satisfactory result. This was later indicated as many world theory. At first, the theory was vigorously disputed and opposed by experts. But after the interpretation of thought experiment it was ruled pure valid. Thought experiment is an imagined experiment that is used to prove the validity of an idea.
Then a new question arose? What are a dimension and how many dimensions exist? Scientist tried to explain the concept of dimension differently this time. This time they discovered a new theory, string theory. According to the string theory every object or matter is made of strings like particles. They compared these strings with guitar strings. When we strum a guitar string, a frequency is generated. If we put our fingers on the fret the frequency changes to another once. Again, when we generate more than one frequency we create a note. The universe works like this way. The world is a symphony and strings generating many notes continuously. The nature is made of note.
But the string theory has five versions, which were supposed to be one. In order to describe what is universe really is we have to understand how the universe was formed. According to the particle physics, there are some building blocks that made the universe. These building blocks have two parts, one part stands for the particles and the other part stands for the force. The particles are made of quarks. These quarks has unusual name like up, down, top, bottom, charm and strange. The particles are muon, tauon, electron and three neutrinos. On the other hand there are four basic forces namely electromagnetism, gravity, strong and weak nuclear force. Among them the gravity is contained by graviton but in theory. Some also said that why gravity is so weak force because it is leaking to another universe. Scientists then announced a new theory, the theory of everything called the string theory.
According to the multi-verse theory, the whole solar system is a part of a galaxy. And there are many solar systems inside a galaxy. And a universe is comprised of such huge amounts of galaxies. It means there are numerous universes that exist. Then there must be a way to connect these galaxies to each other. But many physicists don’t believe that would be possible ever.
Some other people opined that universe is a case of mathematics where rules of probability surely applied. If there is a planet like earth where life exist then it is surely possible too somewhere other is. In fact a finite universe has infinite number of planets. But we cannot see other universes because our cosmic vision is limited. Moreover the space is expanding. This space is called Hubble volume, which represents the observable universe. This is called level 1 universe. Virtually, it is not possible to reach the level 1 universe because it is so far away.
According to the scientists the world is not enough. There is also a level 2 universe and it is reachable but no one knows what we will find there. The theory suggests that there is an inflation gap between these universes. And the universe is expanding. The theory is supported in two ways. The first one is called ‘eternal inflation.’ In this case, when inflation occurs it creates infinite number of universes. The other theory suggests that universe is coated with a membrane. When two membranes collides or touches each other than a new universe emerges.
According to the ekpyrotic theory, the membranes collide with each other at multiple places. Level 3 universe is often portrayed in the science fiction. This suggests that they take place in the same space-time.
The superposition of multiple universes coexists simultaneously. On the other hand, the level 4 universe contradicts classical physics.
