In the world of theoretical physics, the quantum multiverse (also known as the many-worlds interpretation) has gained popularity in recent years as one of the best explanations we have for trying to make sense of what’s going on at the subatomic level. So what exactly is this quantum multiverse? Is it really a thing? And if so, why do we even need it? Let’s take a look at these questions and more to find out how big of a role the quantum multiverse has to play in our understanding of physics.
A Brief History of Multiple Universes
The theory of multiple universes, or multiverses, dates back to antiquity and was most notably proposed by Aristarchus of Samos in Ancient Greece. In 1957, Hugh Everett III is credited for coming up with what we now know as the many-worlds interpretation (MWI) of quantum mechanics and proposing that every possible outcome of every event exists in its own universe. His idea also solved the issue of Schrodinger’s Cat because each time Schrodinger’s Cat opens an eye, a different version of reality occurs.
A few decades later, Stephen Hawking and his colleagues applied this idea to black holes. They argued that if black holes emit radiation then they must eventually lose mass, disappearing at some point. However, according to MWI, when a particle falls into a black hole it splits into an infinite number of new particles, including copies of itself that emerge from other nearby black holes. As long as these new particles don’t fall into the original black hole again before it disappears, then radiation is emitted and matter continues to be lost until the black hole finally vanishes completely. According to modern physics, everything we see around us consists of nothing more than energy on various scales, meaning that all the particles around us are just excitations of a single underlying field. Hence, everything that’s happened so far has happened an infinite amount of times – and will continue to happen an infinite amount more times. While not all physicists agree on the existence of multiple universes, some believe it could help explain dark matter and why gravity is much weaker than other forces such as electromagnetism. Physicist Sean Carroll says: A natural explanation for the apparent weakness of gravity would be if our Universe really were one member of a larger collection.
What Happens Inside a Black Hole?
The black hole is so dense that light cannot escape its gravitational pull, so scientists have never been able to observe one firsthand. But they’ve come up with several theories, most of which revolve around what happens inside the event horizon, which is where gravity becomes too strong for even light to escape. The evidence we do have suggests that when an object falls into a black hole, it stretches out and becomes infinitely thin (a process called spaghettification). Scientists think this might happen because space-time itself is distorted in the region surrounding a blackhole. If you were very close to the event horizon, it would feel like your feet were being pulled down more than your head was pushed up–like you’re being stretched out like spaghetti. Eventually, if you keep falling closer and closer to the event horizon, time will start running slower relative to someone far away from it–to them, minutes might pass but in reality only seconds would have passed on Earth. You wouldn’t notice anything strange at first; the only difference between falling into a black hole and just sitting on Earth is how fast time passes relative to someone else. But as you get closer to the event horizon, the effect gets stronger. As one physicist told Popular Science, If you were right at the edge of a black hole’s event horizon and looking back at Earth, days could go by on Earth while only seconds pass by on your watch. When you finally cross over into oblivion, nothing remains except for your last living memory – good or bad.
The Many-Worlds Interpretation
The idea of parallel universes is not new – it’s been around since the 1800s. But, in 1957, American physicist Hugh Everett formalized this idea into what’s now known as The Many-Worlds Interpretation. The theory goes that when you make a decision or have an experience, you split off into two universes – one where you made that decision and one where you didn’t. For example, if I were to decide whether or not to eat a bowl of cereal for breakfast tomorrow morning, then I would split into two versions: one me who ate cereal for breakfast tomorrow morning and one me who did not eat cereal for breakfast tomorrow morning. Every time we make a choice like this, we create another universe. As time goes on and our choices get more complicated, the number of universes multiplies exponentially. However, according to quantum physics, there are limits to how many worlds can exist. And so far, scientists haven’t found any evidence of anything past 10^10^123 different universes. It’s also possible that there’s some sort of mechanism to limit the number of universes, but they’ve yet to figure out what it could be. In other words, while we may live in a world with infinite possibilities, we don’t know enough about the theory to see much proof of this reality just yet. According to those who follow these types of theories, the best way to think about parallel universes is by imagining all possibilities simultaneously happening at once. What does that mean exactly? Well, imagine yourself standing at your stove preparing pancakes. When you reach up for a bottle of syrup, your left hand grabs maple syrup while your right hand reaches up and grabs strawberry syrup. You’re thinking oh wow! because never before has this happened. So what do you do? Do you put both bottles down and try again, or do you leave them both out on the counter and pick one at random when it comes time to pour it over your pancake stack? To someone else looking from outside the kitchen, they might not understand why you’re hesitating. What? they might ask. Are both maple syrup and strawberry syrup available to grab? Yes, but only one is correct – the other is incorrect. So which will it be?
The Multiverse as Us
Everett’s interpretation of quantum mechanics predicts that every time someone makes a decision, the universe splits into two parallel universes – one where they made the decision and one where they didn’t. As these universes branch off from each other, different versions of reality are created in each one until there are an infinite number of them. So many people ask me if this theory is true, says Neel Mukherjee, professor at University College London’s Centre for Quantum Computation (CQC) but it doesn’t really matter.
Mukherjee notes that the theory is based on abstract mathematics and has not been tested or proved to be correct. Even so, Mukherjee says he believes it could still be true. There is an enormous amount of data to suggest that we live in such a multiverse, he said. Some physicists think this explains the incredibly small size of cosmological constants, for example. Mukherjee added that even though physicists don’t know how many universes exist, the more we understand about our own universe and its laws, the more likely we will find out. He then suggested reading Greene’s The Hidden Reality: Parallel Universes and the Deep Laws of the Cosmos. The implications of all this astounding, Mukherjee said. If you believe in a finite set of physical parameters, like mass, charge and others… If you keep changing their values randomly but within certain bounds, then with the help of computers you can predict the existence of life as we know it.
What It All Means
The theory of a quantum multiverse suggests that for every decision or choice we make, there is an alternate reality where we made the opposite choice. Physicist Brian Greene discusses this theory and what it means for our understanding of time, space and everything in between in his book The Hidden Reality: Parallel Universes and the Deep Laws of the Cosmos. Theories about parallel universes have been around since the 1920s. Many physicists consider them to be logical extensions of Einstein’s general relativity. This has led some scientists to conclude that something like a quantum multiverse might exist. But not all physicists are convinced. And even among those who think that parallel universes may exist, there’s no consensus on whether they’re actually detectable or how one would go about finding evidence for their existence. It’s also possible that each universe could be totally different from another, with some having laws of physics much different from ours. One big question remains: Is the quantum multiverse just a mathematical abstraction, or does it reflect reality? We simply don’t know yet! Quantum mechanics and modern cosmology both present theories that allow for the possibility of other worlds existing outside our own. There’s still so much more work to do before science can definitively answer questions about how many worlds there are and what they’re really like. That said, physicists haven’t found any contradictions in these ideas.
Just as our knowledge about outer space was limited until we developed the technology to explore it, our knowledge of potential other worlds will remain limited until the day when we can find conclusive evidence of them—or until someone else comes up with a way to prove that they exist without ever looking for such proof at all.
