For the Ghouls Whaaaaat?? Mind F*ck series, the Ghouls are discussing parallel universes  what are they? Kat also explains bubble, daughter, and other universes! Gabe discusses the amazing filmmaking behind the film Coherence and finds meaning in the film, Mr. Nobody because every path is the right path!
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RED: Quotes, someone else's words.
Kat's Facts  Parallel Universes and Other Phenomena
Hi friends, how are we tonight? I’m 100% Kat the Kat you’ve known and loved for 106 episodes. I’m here to talk to you about parallel universes, Do they exist? I would like to thank Physicist Brian Greene, who very neatly answered this question for me on an NPR special via fresh air, titled “A Physicist explains why parallel universes may exist”
He says it in a way that 9 hours workday Kat could understand after her brain was radiated into mush. He says “Our universe might be really, really big — but finite. Or it might be infinitely big. Both cases are possibilities, but if the latter is true, so is another posit: There are only so many ways matter can arrange itself within that infinite universe. Eventually, matter has to repeat itself and arrange itself in similar ways. So if the universe is infinitely large, it is also home to infinite parallel universes.”
So if the universe is infinite, there would be universes with versions of ourselves having varying differences that could either minimally or largely impact us. This reality is obviously more interesting. The current theory around this states that we would never interact, and that our universes will not touch each other, instead just existing parallel to each other. Green explains this using a deck of cards as an example, stating that if the Universe is a deck of cards, and matter can only be arranged in a certain amount of ways, there would have to be versions that repeat, and versions with varying differences.
So there are a handful of theories around the different variations of universes. Space.com talks about them
2. Bubble universes. Another theory for multiple universes comes from "eternal inflation." Based on research from Tufts University cosmologist Alexander Vilenkin, when looking at spacetime as a whole, some areas of space stop inflating like the Big Bang inflated our own universe. Others, however, will keep getting larger. So if we picture our own universe as a bubble, it is sitting in a network of bubble universes of space. What's interesting about this theory is the other universes could have very different laws of physics than our own, since they are not linked.
3. Daughter universes. Or perhaps multiple universes can follow the theory of quantum mechanics (how subatomic particles behave), as part of the "daughter universe" theory. If you follow the laws of probability, it suggests that for every outcome that could come from one of your decisions, there would be a range of universes — each of which saw one outcome come to be. So in one universe, you took that job to China. In another, perhaps you were on your way and your plane landed somewhere different, and you decided to stay. And so on.
4. Mathematical universes. Another possible avenue is exploring mathematical universes, which, simply put, explain that the structure of mathematics may change depending in which universe you reside. "A mathematical structure is something that you can describe in a way that's completely independent of human baggage," said theoryproposer Max Tegmark of the Massachusetts Institute of Technology, as quoted in the 2012 article. "I really believe that there is this universe out there that can exist independently of me that would continue to exist even if there were no humans."
5. Parallel universes. And last but not least as the idea of parallel universes. Going back to the idea that spacetime is flat, the number of possible particle configurations in multiple universes would be limited to 10^10^122 distinct possibilities, to be exact. So, with an infinite number of cosmic patches, the particle arrangements within them must repeat — infinitely many times over. This means there are infinitely many "parallel universes": cosmic patches exactly the same as ours (containing someone exactly like you), as well as patches that differ by just one particle's position, patches that differ by two particles' positions, and so on down to patches that are totally different from ours.

Schrödinger’s cat experiment is what we call a thought experiment. In other words, we don’t actually conduct the experiment, we use only our imagination and reasoning instead. In fact, as we will later learn, it is truly impossible to physically conduct Schrödinger’s cat experiment, even if we wanted to.
During the 1920s and 1930s, a new scientific revolution was occurring. Now, science realized that an entirely new realm existed on the smallest possible levels, quantum. Perhaps, among the greatest of quantum physics’ forefathers, Austrian physicist, Erwin Schrödinger.
First, a cat is placed inside a sealed box for one hour. Also, inside the box are a container of radioactive material, Geiger Counter (simple machine that detects radioactive particles), hammer and container of deadly cyanide. Using the correct radioactive material allows a precisely 50/50 chance that within one hour, a single radioactive particle will be emitted. Basically, nothing about matter is certain until we observe it. In fact, this thought process is known as the Copenhagen Interpretation of quantum physics. In other words, simply looking at matter actually changes the outcome of what happens to it!
After one hour in the experimental box, Schrödinger’s cat stands a 50% chance of being dead, and 50% chance of being alive
But, while the cat is in the box, it is both dead AND alive simultaneously (Copenhagen Interpretation)
Schrödinger’s cat experiment was hypothetically used to show Schrödinger’s disagreed with the Copenhagen Interpretation for larger objects, like a cat!
Sources:
https://www.space.com/32728paralleluniverses.html
https://www.npr.org/2011/01/24/132932268/aphysicistexplainswhyparalleluniversesmayexist
https://now.tufts.edu/articles/beginningwasbeginning
https://astronimate.com/article/schrodingerscatexplained/