- According to the Belgian physicist Georges Lemaitre, the universe has been expanding since 13.8 billion years ago.
- There is no place where we can go to confirm that there is indeed the edge of the universe and look at what is beyond.
- If space extends beyond our universe, there is a possibility of other universes existing beyond the one we know.
The Universe is the total of all the things that exist in space, including stars, planets, asteroids, galaxies, light, etc. It is incredibly huge and it is expanding at an accelerating rate. However, does anyone actually know the exact size of the Universe?
To ask such a question about the Universe would mean that the Universe has an edge. Defining the "borders" of the Universe or the end of space is not a simple task, even for scientists. Most of the time, the answers to these questions depend on the perspective, and some of them, we will probably never find out.
The Universe Expands In Mysterious Ways
We now know that the Universe is expanding, and it has been expanding since 13.8 billion years ago, according to Belgian physicist Georges Lemaitre. Later, Edwin Hubble concluded that galaxies are pulling away from us and that at some period in the past, all of the galaxies were at the same place. This led to the universal acceptance of the Big Bang model.
However, if the Universe is expanding, what is it expanding into? Is there anything at all that is beyond the universe? Unfortunately, there is no place where we can go to confirm that there is indeed the edge of the universe and look at what is beyond. Something does not have to be infinite to not have an edge or an end.
The easiest example is the surface of a sphere, a geometrical object that has no bottom and no top. We can walk in any direction and we would come back to where we initially started. The sphere is finite, but there is no edge per se. But, we still do not know for sure if the universe is infinite in space, or if it resembles a sphere. Even if there is an end to the universe or it has a boundary (which is highly unlikely), we will probably never be able to observe it.
The Multiverse Theory
These questions are also responsible for stimulating the idea of the multiverse (a group of multiple universes). Our planet is located within the solar system and that solar system is one of many different solar systems that are contained inside a galaxy, and there are also many different galaxies in the universe, but that is still only one single universe.
If space extends beyond our universe, there is a possibility of other universes existing beyond the one we know. Some cosmologists and theoretical physicists, like Laura Mersini-Houghton (from the University of North Carolina) have proven, with mathematical certainty that parallel worlds (like our own) exist. In a way, it is a consequence of the laws of physics, but it is not observable.
The problem is empirical falsification and that is why there are certain disagreements over this theory in the physics community. Some scientists reject it as a scientific hypothesis and approach it with a philosophical perspective. Whatever your perspective is, it does not seem plausible that we will have definite answers to these theoretical questions.