Approximately 13.75 billion years ago, our universe came into existence. Very shortly thereafter, primordial light started shooting across the cosmos and spread all over the early universe. At this juncture, the universe itself was also growing. The inflation of the universe decelerated after the first initial burst, but since then, the rate of expansion has been progressively increasing due to the influence of dark energy.
Fundamentally, since its inception, the cosmos has been expanding at an ever-increasing rate. Cosmologists guesstimate that the oldest photons that we can observe have really traveled a distance of 45-47 billion light-years since the Big Bang. That implies that our observable universe is approximately 93 billion light-years wide. These 93 some-odd billion light-years cover all of the quarks, quasars, stars, planets, nebulae, black holes and everything else that we could probably observe; but the observable universe only contains the light that has had time to reach us.
It is widely believed that there is a lot more universe beyond what we are able to observe. The common queries are – how can the universe be 93 billion light-years across if it is only 13.8 billion years old or even that light hasn’t had enough time to travel that far…? Eventually, understanding this aspect of physics is the key to understanding what lies outside the edge of the observable universe and whether we could ever get there.
According to special relativity, objects that are close together cannot move faster than the speed of light with respect to one another; but there is no such binding law for objects that are extremely distant from one another when the space between them is, itself, expanding. In brief, it’s not that objects are traveling faster than the speed of light, but that the space between these objects is expanding, causing them to fly away from each other at remarkable speeds.
In the end, this means that we can reach the edge of the observable universe only if we develop a method of transport that allows us to either travel faster than the speed of light considered impossible by physicists or transcend spacetime by using wormholes or warp drive, which is also unlikely according to most physicists.
The theory of cosmic inflation states that the entire universe’s size is at least 10^23 times larger than the size of the observable universe. That’s a whole lot of universe that we are missing. What is really outside the observable universe? Regrettably, since we can’t see it or measure it, we just don’t know what lies beyond the bounds of the observable universe. However, we have numerous theories regarding what exists in the great unknown.
Encountering The Unknown
Notwithstanding its strangeness, this first idea easier to digest. Astronomers think space outside of the observable universe may be an infinite expanse of what we see in the cosmos about us, distributed in a manner which is the same as it is in the observable universe. This appears logical. After all, it doesn’t make sense that a section of the universe would be different than what we see around us. And it will be weird to envision a universe that has an end like a huge brick wall lurking at its edge.
Therefore, in some ways, infinity makes sense. But “infinity” signifies that, beyond the observable universe, you won’t just discover more planets and stars and other forms of matter, you may eventually find every possible thing that is even beyond our imagination.
This implies that if this holds true and we follow it to its logical conclusion, somewhere out there, there may another person who is identical to you in every possible way, and there may also be a you who is only slightly different from you in every possible way – in height or age. In fact, this “other you” may even be reading this article right now. This notion seems inconceivable but then, infinity is somewhat inconceivable.
Another popular theory involves “dark flow.” In 2008, astronomers discovered something very strange and unanticipated in galactic clusters that were all streaming in the same direction at immense speed, more than two million miles per hour. One possible cause was hypothesized as massive structures outside the observable universe exerting gravitational influence. As for the structures themselves, they could be figuratively anything. Astoundingly huge accumulations of matter and energy beyond our imagination or even strange warps in space-time that are funneling gravitational forces from other universes. We just don’t know what these massive objects could be. Remarkably, recent analyses have claimed to debunk the dark flow model, but it is still being disputed.
Another hypothesis involves a universe of universes. Some believe that our whole universe exists in a small “bubble” in the midst of a vast array of other bubbles. Theorists term this a “multiverse.” Fascinatingly, this idea asserts that these universes actually come into contact with one another as gravity can flow between these parallel universes. So, whenever they connect, a Big Bang like the one that created our universe may occur.
Hopefully, soon we will unravel the true mystery of lies beyond.