If there is a multiverse, it's possible that there might be another you out there doing exactly the same thing as you are doing right now.
Multiverse theory proposes that the universe with its billions of galaxies, and nearly countless stars, which spans tens to billions light-years, might not be the only one. There may be another universe that is distantly different from ours. There may indeed be many universes with their own laws of Physics, their own collection of stars and galaxies (if they can exist in those universes), or even their own intelligent civilizations.
Perhaps our universe is only one of many universes that make up the multiverse.
Related: 10 wild theories of the universe
Theoretical evidence for the multiverse
Although there are many areas of physics and philosophy that discuss the concept of the multiverse, the most well-known example is inflation theory. Inflation theory is a description of a hypothetical event that took place when the universe was less than one second old. NASA reports that the universe experienced rapid expansion in a very short time. It "inflated" to become many orders-of-magnitude larger than it was before.
Heling Deng, a cosmologist from Arizona State University and expert in multiverse theory, stated that inflation of the universe was thought to have ended around 14 billion years ago. Deng explained to Live Science via email that inflation doesn't end in all places at once. It is possible for inflation to end in one region and continue in another.
While inflation has ended in our universe, it is possible that inflation continues in other regions, which may be much further away. Individual universes may "pinch off", expanding larger universes that are constantly inflating and expanding, creating an endless sea of infinite inflation filled with many universes.
Each universe would have its own laws of Physics, its own collection and arrangement of particles, and its own fundamental constants. This could explain why the universe exhibits certain properties, Deng stated.
He said, "If there were a multiverse, then there would be random cosmological constants across different universes. It is just a coincidence that one we have in this universe takes the same value as we observed."
Related: Cosmology: Uncovering the Story of the Universe
The most important evidence for the multiverse's existence is that intelligent life can make cosmological observations. McCullen Sandora, an associate research scientist at Blue Marble Space Institute of Science, stated that certain aspects of the universe are important for supporting life. These include the existence of stars and their longevity, as well as the abundance of carbon and light available for photosynthesis. Sandora explained to Live Science that "all these features are not the case when you get handed an random universe." Sandora stated that the multiverse is one explanation for all the favorable features in our universe. It's possible that other universes exist, but we only observe one universe because it can support complex life.
This means that life could not have been possible if so many things were in sync. Even if only one universe existed, life wouldn't likely exist in it. However, in a multiverse there is enough chance for life to appear at least once in each universe. However, scientists are skeptical about the multiverse theory because it isn't convincing.
Multiverse theory suggests that inflation might not happen at the same pace everywhere. Individual universes could "pinch off", creating infinite oceans of expanding universes. Image credit: Getty Images
The multiverse is physically evidenced
Scientists have been trying to find physical evidence that the multiverse exists. If a neighboring universe was close to ours in the past, it could have collided with ours, leaving a visible imprint. According to University College London, the imprint could take the form of distortions of the cosmic microwave background (the remnants of when the universe was one million times smaller than today), or strange galaxy properties in the direction the collision took place. However, all these searches have failed, so the multiverse is still hypothetical.
Related: Where are the multiverse worlds hidden if we live in a multiverse?
Deng is looking for evidence of the multiverse. He is searching for special types of black holes, which could be artifacts from pieces of our universe that have separated via quantum tunneling. According to Deng, if some regions of our universe split this way, they would have left behind "bubbles", which would then turn into these unique black hole, which could still exist today.
Deng stated, "The detection of black holes could point to the existence a multiverse."
The multiverse: Life in it
The existence of doppelgngers is perhaps the most bizarre implication of multiverse. The existence of doppelgngers is a paradoxical implication of the multiverse. If there are infinite universes, but only a finite number ways to arrange particles in each universe, then these patterns will be repeated eventually. This would mean that there is an incredible, but finite distance between you and the exact copy of this article. This would mean that at some incredible (but finite!) distance, there would be an exact replica of you reading this article. According to the Institute of Physics, because there are infinite universes, these scenarios could all be happening simultaneously.
Related: What would humans learn if they lived in multiverses?
If you find this uncomfortable, it might be comforting to know that the multiverse is not yet proven to exist.
