The Human mind can perceive only four dimensions. The first three being physical dimensions such as length, breadth and height, and the fourth being the Time dimension. That is why we can see, hear, feel and touch only those entities which exist in the three dimensional world. Our sensory organs control how we perceive the universe that we live in and we believe in the reality that our mind presents before us.
The multiverse is a hypothetical group of multiple universes including the universe in which we live. Together, these universes comprise everything that exists: the entirety of space, time, matter, energy, and the physical laws and constants that describe them. The different universes within the multiverse are called “parallel universes”, “other universes”, or “alternate universes”. The idea of different worlds and dimensions floating around might seem absurd and bewildering to some, but it is not just some random idea that scientists came up with. This is a hypothesis which has solid physics and mathematical evidence to back it up and which, if true, holds answers to several anomalies and discrepancies in quantum physics. There are numerous theories (e.g.: The String Theory) that point to the fact that there are multiple parallel universes out there, and some experts believe that chances are high that hidden universes actually exist in plain sight.
Concepts of a multiverse are also evident in the cyclical infinite worlds of ancient Hindu cosmology. According to Hindu Vedic cosmology, there is no absolute start to time, as it is considered infinite and cyclic. Similarly, the space and universe has neither start nor end, rather it is cyclical. The current universe is just the start of a present cycle preceded by an infinite number of universes and to be followed by another infinite number of universes.
It is also possible for each universe to have multiple dimensions and not just the four we humans can perceive. According to the Puranas and the Atharvaveda, our universe consists of 7 upper (Vyahrtis) and 7 lower (Patalas) planes of existence: Satya-loka, Tapa-loka, Jana-loka, Mahar-loka, Svar-loka, Bhuvar-loka, Bhu-loka, Atala-loka, Vitala-loka, Sutala-loka, Talatala-loka, Mahatala-loka, Rasatala-loka and Patala-loka. The concept of multiple planes or dimensions is echoed in several other religions such as Buddhism, Judaism, Christianity and Islam. Thus, it is evident that the concept of multiple universes and/or multiple dimensions is not new. It is something which has been known or pondered upon since antiquity.
Let us take the example of fire or a burning flame. It has neither length nor breadth nor any thickness. Yet, we can see the the light emanating out of the flame and feel its warmth. We cannot physically touch it or hold it, yet we get burnt by the flame if we come in contact. Can we define its existence in any of the three dimensional physical planes? We cannot; yet, we know it exists. It is possible that the flame exists in a different dimension and is perceivable to us only by our sense of sight. If we were not able to see the flame, it would not be possible for us to sense its existence. We might have felt its warmth but we could have never identified the location of the flame if it was not visible to us. Similarly, there might be an infinite number of dimensions around us which our limited senses are not able to perceive but it does not mean that they do not exist. It is possible that we may be able to travel or move to these other dimensions or planes in future once we achieve a certain level of technological and psycho-physiological advancement. This could also potentially explain the sudden appearance and disappearance of Gods and other worldly beings as depicted in several religious and historical scriptures across the world. It may be that these evolved beings had the capability to transcend our three dimensional world and move between various planes of existence. Modern science explores such a possibility by means of wormholes.
A wormhole is a theoretical passage through space-time that could create shortcuts for long journeys across the universe. Wormholes are predicted by the theory of general relativity and may offer a plausible explanation and solution for inter-galactic travel through the space-time continuum. If this hold true, then we should probably not limit our search for extra terrestrial intelligence within our perceptible universe or three dimensional world. It is time to explore and revisit our perception of reality and undertake research to create break-through technologies which may be able to transcend physical barriers.
The Multiverse and Multi-dimensional universe are possibilities not yet proven by science but accepted by many as a possible reality. The sooner we accept it the better it would be for the evolution of mankind.