The universe is filled with so much possibility. We don’t know what the future will bring — or what else is out there. That’s because we only see a tiny sliver of it. Many galaxies in our Milky Way galaxy alone have never been observed. And believe it or not, there are other universes out there. There are more than 100 billion stars in the Milky Way, most of which aren’t visible from Earth.
The only way we could see all of these stars, if they were close enough for us to reach out and touch them, would be with a telescope. The farther away something is from us, the larger its apparent diameter so that we can look through a telescope at it and see virtually everything about it. It means that there are even more stars out there than we can currently see with our eyes! But how did this entire universe get started?
We can think of it as getting its mini-big bang — one that made some extraordinary things in the universe possible but others impossible. And what would happen if one of these universes collided with another? In this article, we explore some possible scenarios that could result from such an encounter; what impact they might have on our world; and how scientists think about them today.
In the early stages of the universe, the two galaxies that make up our Milky Way experienced a fierce collision that led to the formation of the first stars and planets. In this scenario, the two galaxies merged into one more giant galaxy that contained between 10 and 100 times the number of stars in either of the original galaxies. The merger produced enough heat and light to create the first black holes — and, perhaps, another type of dark matter that makes up a significant portion of the rest of the universe.
In this scenario, our galaxy is the one that meets a galactic extinction — a point in time when all the stars in the galaxy would be so far away that the Milky Way can’t see them. As a result, the Milky Way encounters a smaller galaxy far less dense than ours and contains much less mass than the Milky Way.
As the smaller galaxy tumbles toward Earth, objects such as stars, planets, and galaxies (including our own) smash into one another, creating an environment that is extremely violent and full of energy. It is the most catastrophic event in the entire universe, and it would result in the creation of a black hole — the remnant of which is still being studied after 3.8 billion years.
It is one of the more “futuristic” collision scenarios, but it has some basis. The first one to postulate the idea was prominent astrophysicist Neil deGrasse Tyson, so it’s not too far off the mark. In this scenario, our galaxy is the outermost member of a much larger galaxy. As our galaxy collides with the galactic center, the material is flung out in all directions, and one of the primary sources of this material is a binary star system.
While the binary system is probably not large enough to contain the equivalent of our sun, a small star-like object can be 1.2 times the mass of our sun would form in its place.
Big Bang-Big Crunch
It’s not clear if this is a thing that could happen in the universe, but it’s what we call “theory” at the moment. It is one of the more “futuristic” collision scenarios and one of the most interesting. In this scenario, our galaxy is the outermost member of a much larger universe. As the larger universe moves away from us, it leaves our galaxy in its wake of stars, galaxies, and planets.
It is believed that our universe is one of those planets — the densest within the cosmic neighbourhood. As the universe expands, it overlaps our galaxy for a time, leaving behind a smaller, denser galaxy. After the expansion has stopped, we might find our universe part of a “tandem” with another universe in a “Big Bang -Big Crunch” event.
Currently, scientists don’t know enough about the Big Bang to say what would happen if it came back. However, there are a couple of things we do know. The first is that the Big Bang would come back if it happened elsewhere in the universe. The other is that it would be tough to bring back.
In this scenario, our universe is in the final stages of expansion. It’s getting pretty big, and more matter is being added to it than is being pulled away. The expanding universe is adding more matter to our universe than was present in the whole of our galaxy just 40,000 years ago.
Parallel Universe Collision
It is one of the more “futuristic” collision scenarios, but it is one of the most likely. It is based on the idea that our universe could have come out of a parallel universe. In this scenario, our universe is similar to the other universes in that it was created quite a while ago. However, they were created quite a while apart, and when our universe was created, the other universes were still spinning on their axis, and so were our galaxies.
Today, our universe is the only one that exists, and our galaxy is the only galaxy in the entire universe. Over time, due to its expansion, our galaxy will cross paths with other galaxies and our universe, eventually merging to form a giant galaxy. Our universe could come into contact with a much younger universe than our own, which would give rise to a lot of excitement because there would be new kinds of particles and forces to explore.
Big Bang Explosion
It is the most catastrophic scenario, and it is also the most likely. It is based on the idea that the universe underwent a catastrophic explosion that created the first stars and galaxies. The universe’s expansion then continued to create more galaxies and stars. In this case, the universe would have been much younger than it is now, with very few elements heavier than helium.
It would have created a much less dense environment than we see today. A merger of two galaxies similar to the binary union above would also have occurred, and our universe would have become one of these more giant galaxies.
Big Bang Contraction
In this scenario, the universe initially expands very quickly. It is then slowed down by an unknown force over time, eventually reaching a point where the gravitational attraction of our galaxy would have been sufficient to cause it to stop expanding and form a star-like planet. The atmosphere of this planet would have been very different from our own, with little to no carbon and other elements heavier than helium.
An Alien Invasion
In this scenario, our galaxy collides with another, possibly due to a black hole collision. The two galaxies then become involved in a battle for control of the universe. Out of this battle, our galaxy is displaced into a different galaxy. This new galaxy is similar to ours in many ways, but it also features different elements, including oxygen, that we do not have.
It changes the atmosphere, temperatures, and composition of the universe. The galaxy then confronts an even more demanding environment, and it cannot support life as we know it. Therefore, life on this planet is different from what it would be in a universe without life.
We may think of our universe as a cozy little corner of space, but when another universe comes into contact with it, it could send shockwaves through our world. The physics of such an interaction are quite different from our own, so that the outcome could be very different. According to one theory, our universe could result from a galactic collision with another galaxy.
As the two galaxies clashed, their planets and moons could have been ripped away and sent spinning through space. Our world may have been formed from the remains of feasting upon bits of those two ancient celestial spheres. This theory is called panspermia, and it’s based on the fact that every planet in the universe is made of the same elements as our planet and that similar elements are found on every planet in every other galaxy.
It even makes sense that we exchange elements with other planets through space instead of being born as part of a planet-eater cosmos. But there is much room for improvement in this theory. For instance, how do we know that the same elements that made up our planet survived the collision? If not, this theory could have very dark implications for our planet.
Supernovae are a clear indication that something extraordinary happened in the early universe. These events occur when a massive star runs out of fuel (i.e. hydrogen) and dies. As it goes, it produces a big bang followed by a short burst of intense light. A supernova is just such a light burst, and it’s what we see when we look through a telescope when the universe is very young. Essentially, we get light from a supernova being reflected off another galaxy.
The supernova we see in this image results from a star that exploded about 10 to 20 times the sun’s mass a few hundred million years ago. We only see this event once every few hundred million years, and then it’s gone. While we’re on supernovae, let’s talk about the other kind of light we see coming from a supernova: radio waves. These are the leftover sounds from the supernova itself, and they can be detected with radio telescopes thousands of light-years away from our galaxy.
As we’ve already discussed, our universe could easily result from a single supernova event. But many scenarios suggest that our universe was formed by colliding two or more galaxies. This kind of universe-in-construction scenario was first described in 1980 by the American theoretical physicist and cosmologist Allan Sandage. In this model, the initial supernova in our galaxy is followed by a scenario in which other galaxies are crushed together in a galactic clash.
The most popular scenario is one in which our universe was formed by the collision of two or more galaxies. This scenario is perhaps the most common form of cosmic genesis, and it’s based on the idea that the Milky Way and its four closest galactic neighbours formed one supercluster during the early universe’s infancy. This scenario could produce many other scenarios, including a hot soup of dark matter and dark energy or one in which our universe is the only one in existence.
This supercluster — which is thought to contain a few thousand galaxies — eventually fragmented into individual galaxies. But what if we were the lucky ones to get put into this scenario? What if all we had to do was wait?
Time Dilation at Close Range
Time seems to flow much more slowly in a close-range encounter between two universes than in our own. For instance, during a close encounter, the speed at which atoms and molecules in either universe can complete one cycle of creation and destruction is just a tiny fraction of the speed of light.
In the above scenario, one could also assume that time is dilated or slowed by the presence of dark matter and energy in the universe we find ourselves in. It means that the events of our world are recorded differently. As a result, for various effects like decay, time may be slightly over one second in the universe we find ourselves in, but on the other side, it may be slightly under one second in the other universe.
What would this mean for our world? Well, it would essentially mean that there would be very different laws of physics and a different way of looking at the world we see around us. But, of course, if this were to happen, there would be no way to know what would happen.
An Endless Improbable Future
There is one scenario in which all of this is possible. That is the multiverse hypothesis. This scenario posits many other universes like ours, each with its own rules. It’s not something scientists would necessarily consider a “doomsday scenario,” but that many people — even those who believe in an eventual apocalypse — find complicated to imagine.
If the multiverse hypothesis were true, the possibilities would be almost endless. There are an infinite number of different universes (if the universe we live in is among them). Some of these may be very similar to ours, while others may differ. Some may have life, while others may not. One could conceivably end up with everything from rainbows and rainbows to dinosaurs and spaceflights in between.
It is how the researchers at George Washington University and the University of Chicago came to believe in the multiverse. George Washington University astronomer Prentice Halley said it’s a fascinating possibility when we start believing in the theory. He also said that we’re constantly looking for new ways to look at things, and this is one way to go about it.
If you’re still unsure about the direction things should go, consider this: If the universe is made of pure energy, then anything that happens in it could affect our world. So, for example, an encounter with another universe could result in the creation of more energy or minor matter in our world — or the reverse. It could even bring new life forms or change our planet’s climate. This scenario is possible, yet it’s not something scientists necessarily consider a “doomsday” outcome. It’s simply too early to tell.
Our universe is very young, less than 6 billion years old, and only about 25% the size it would be if it had been around for a more extended period. The universe is also filled with so much potential, and it’s hard to predict what might happen in the future. It’s, therefore, hard to say how the collision between two universes would affect the present state of our universe.
It’s possible that the collision would create more matter and energy than either of the two universes could contain — or that one of the resulting universes would be so different from our own that it would be impossible to exist in our universe as a living, breathing thing. As the saying goes, the universe may end, but the questions will never end.
We still don’t know how the universe began, why it’s the way it is, or what lies in store for the global future. We do, however, know that the universe will continue to exist for as long as the matter in the heavens can condense and merge into a recognizable form.
If you liked this, check out Exploring the Murky World of Parallel Universes: Are We Living In A Multiverse?