As we live longer and longer we humans discover more about our surroundings. Many people thought many things in ancient times about the earth; some said the earth is flat and some said if you sail too far and you surely will drop into oblivion. At that time it was a truth, but now we know it’s not. Theory of parallel universe is quite interesting. A young doctoral candidate of Princeton University named Hugh Everett III came up with a far-reaching idea in 1954. The idea was complicated and the idea was there exist parallel universes just like ours universe. Afterwards a physicist named Alan Guth derived a parallel universes theory based on many observations. His observation was based on an inflationary universe also known as the inflationary theory of cosmology. A little overview of this theory is below.
The universe as we know it initiated with a great explosion that we call the big bang but many think that it was not an explosion rather than just a rapid expansion of space and time. For almost a century cosmologists have been studying that what happened after that explosion or rapid expansion. How the universe expanded and cooled down in order to support life like on earth. The nature of the explosion or rapid expansion of space and time; it has come into concentration properly lately. It is the theory of inflation; this theory was established in the 1980s by Alan Guth, Andrei Linde and has led to the new common view of the universe as we know it. Inflation is actually a period of super-fast, speeded expansion in the early history of formation of the universe. It is very fast, so fast that in a tiny segment of a second a tiny subatomic dot of space and time is wafted to dimensions, which are greater than the whole current observable region. At the very end of this inflation process, the energy that crowd the expansion causes a hot flash of particles and radiation to ignite. This is known as the big bang.
In our intergalactic neighborhood that process of inflation as described above has ended 13.7 billion years ago, but it still remains occurring in distant parts of our universe. These new regions seem as tiny, microscopic bubbles and they instantaneously start to propagate. These bubbles making a room cause other bubbles to form like chain reaction driven by inflation process. This never-ending procedure is also known as an eternal inflation. So we live in a one of these bubbles and can observe a tiny region of it. It does not matter how fast we travel, we cannot reach the end of this expanding bubble, so we live in a self-contained bubble universe.
All the theories related to parallel universe exist because we do not know and we cannot see what’s beyond the cosmic horizon (that’s about 14 billion light years). This is also known as level 2 parallel universes. As we all know that quantum mechanics defines the whole world as we know it in terms of probabilities, instead of definite outcomes. And the mathematics of this theory suggests that all possible consequences of a particular situation occur at the same time but, they only occur in their own distinct universes. Let’s take an example to clearly understand this process. If you reach a junction where you have two choices to go and that surely are right or left, the current universe in which this situation is happening gives rise to two other daughter universes depending on the options you have: one in which you can go right, and one in which you can go left. This is also known as level 3 of parallel universe. The Level 4 parallel universes are totally different ones which are ruled by different equalities (equations) from those which currently are ruling our universe. In level 1 parallel universe, an infinite universe will comprise an endless sum of Hubble volumes; all will have the same physical constants and physical laws.
Well parallel universe is not just an imagination but it can be true and way of knowing the answer of this question is to know what is beyond cosmic horizon. With time everything will get clear so let’s wait and watch...