The True Science of Parallel Universes
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The True Science of Parallel Universes


Everyone loves the idea of parallel universes
– maybe it’s the appeal of an ideal world where you have second chances and things turn
out differently – an alternate reality where you do get into Hogwarts and the Star Wars
prequels aren’t made and you finally plug in your asymmetric computer cord correctly
on the first try… but is there really a place in science for such wistful speculation? I mean, if “the universe” is everything that
there is, you can’t have two versions of it, right? Otherwise the pair would really be
everything and what you started off calling the universe, wasn’t. The problem here is terminology: physicists
speaking informally often say “universe” when they really mean “observable universe” – that
is, the part of the whole universe that we’ve so far been able to see. And it’s perfectly
fine to talk about multiple different observable universes – for example, an alien near the
edge of OUR observable universe will see parts of the Whole Universe that we cannot yet see,
but that’s a well-understood question and not what physicists normally talk about when
they discuss multiple observable universes, or “multi-verses.” So let’s cut to the chase: in physics, the
word “Multiverse” normally refers to one of three distinct and largely unrelated proposed
physical models for the universe – none of which has been tested or confirmed by experiment,
by the way. The three “multiverse” models are: Type 1) Bubble universes or baby black hole
universes. This is the most straightforward kind of multiverse: the basic idea is that
perhaps there are other parts of the universe which are so far away that we will never see
them (or are inside black holes so similarly we will never see them).
This kind of model was created as an attempt to explain why our universe is so good at
making stars and galaxies and black holes and life – as the argument goes, if each of
these separate mutually un-seeable “bubbles” in the universe had slightly different laws
of physics, then by definition we could only exist in one that had the right physical laws
to allow us to exist. If you’re not convinced by this logic, don’t worry too much: there’s
not yet any experimental evidence for this kind of multiverse.
Multiverse type 2) Membranes and extra dimensions. Inspired in part by the inability of the mathematics
of string theory to predict the right number of dimensions for the universe in which we
live, string theorists proposed the idea that perhaps what we think of as our universe is
actually just a three-dimensional surface embedded within a larger super-universe with
9 spatial dimensions. Kind of like how each page of a newspaper is its own two-dimensional
surface embedded within our three-dimensional world.
And of course, if space had 9 dimensions rather than three, there’d be plenty of space for
other three-dimensional surfaces that appeared, like ours, to be universes in their own right,
but, like the pages of a newspaper, were actually part of a bigger whole. These kinds of surfaces
are called “membranes” or “branes” for short. And as a reminder, there is not yet any experimental
evidence for this kind of multiverse. Multiverse type 3) The many-worlds picture
of quantum mechanics. Surprisingly, physicists still don’t fully understand how the collapse
of the wavefunction in quantum mechanics happens, and the many-worlds hypothesis makes an attempt
at explanation by proposing that every possible alternate timeline for the universe is real
and they all happen in an ever-larger, ever-branching way. Like, a universal choose-your-own-adventure
where every possible story happens! If this were the case, we might not realize
it because we’d be stuck living out just one of the infinitely many possible lives available
to us. In some ways, many-worlds is similar to the bubble multiverse model by proposing
“maybe anything that can happen, does. And we just happen to exist in the series of happenings
that were necessary for us to exist.” If you’re still not convinced by this logic, don’t worry:
there is not yet any experimental evidence for this kind of multiverse. Of course if you want to get imaginative,
you could also combine several of these models together into a multi-multiverse… a new
super-speculative model based, itself, on speculative and experimentally unconfirmed
models. But that’s not to say we couldn’t test these
multiverse hypotheses. For example, if our observable universe were really just one of
many disconnected bubbles or membranes and if it happened to collide with another bubble
or membrane some time in the past, then that collision would certainly have had some sort
of effect on what we see when we look up at the night sky.
On the other hand, the many-worlds interpretation might be tested fairly soon since experimentalists
are becoming increasingly able to manipulate and control ever-larger quantum mechanical
systems in their labs – systems that approach the line between the quantum realm and our
everyday experience. So as always, we must remember that physics
is science, not philosophy; and in our attempts to explain the universe that we observe, we
have to make claims that can in principle be tested – and then test them!

100 thoughts on “The True Science of Parallel Universes

  1. If there are multiple universe there must be a universe in which that universe have discovered a way to connect to our universe

  2. What if our dreams were tiny/faded memory from infinite number of realities, think about it.

    Yes, the dream you had last night was probably from a small tiny memory from another alternate universe.

  3. If universes splits whenever we make a decision and we’re aren’t aware of it because we only live in the decision we made then the original me is when before i ever learn how to make decision right?

  4. 2:20 ectually each page of a newspaper is 3 dimensional since we humans can only see objects that exist in the 3rd dimension. Not 4th but neither 2nd or 1st. Which is because our vision works based on light and if we have a 2d object from let's say 1m by 1m it would mean x=1 and y=1 but z=exactly 0 which means light passes trough.

    The z for a newspaper isn't exactly 0 tho that's why we can see it

  5. in another universe, you’re the popular one. you have everything you want, everything you’ll ever need. but, you’re stuck in this one, so do your best

  6. Unknown people we see in our dreams are former human being spirits we travel and vision things through our spiritual body once we sleep …..

  7. My friend and I have talked for hours about the third one and how if we did a thing a different way how different the present and future would be. And I’ve had these deep thoughts by my self playing Minecraft thinking if I built this an hour later (I build without a plan like an idiot 99.999%of the time) how different would it be than what I just made. Also on the topic of Minecraft my friend said if I waited just a bit longer we wouldn’t have gotten the seed we got.

  8. I actually think other universe has developed more technology than us which allow them to travel through the universe and study ours, it’s like they returned in the past. While other universes are still living earlier than us in the past.

  9. Thought:
    Following the idea of the 'Many Worlds' model, at least one of the following statments must be false:
    1) There are a truly infinite number of parallel universes
    2) You can travel freely between universes
    3) My understanding of this model is flawed :/
    Because…
    if there were an infinite amount of universes and you could travel between them, there would be an infinite number of mes traveling to this universe and giving me a million dollars. Evidently there are not, therefore one of these things must be false.

  10. Everyone’s knows about the parallel universe theory. My theory parallel Earth. The Earth is flat is just duplicates forever without changing anything though when you reach the “side of the earth” you just go to a newly copied earth that the same thing happened as the original. if their is one.

  11. Why are people comforted by the thought of alternate universes where they have better lives? By that logic shouldn't you also be disgusted by the thought of all the alternate universes where you're a scumbag.

  12. Alternate universes may exist, but they won't contain alternate versions of you. They'd likely contain worlds where the laws of physics themselves would be different. In order for other worlds to have alternate versions of you, that would mean each decision you make must have a definitive answer (a.k.a predetermined destiny) which isn't real.

  13. I dont understand anything this guy is talking about. I am very small brain. I think he needs to dumb it down a bit for people like me QwQ

  14. But what I don’t get is when people say I could be a rock star or really beautiful in another universe, but if you were a rockstar you wouldn’t be you, for instance if my mum became a lawyer instead of a journalist she wouldn’t of met my dad and had me so I wouldn’t be here, similarly if I were something else I wouldn’t meet the people I meet and I would have different kids. That part really confuses me, because they say you would look the same, but then how does that work?

  15. I don’t believe in the many worlds interpretation of Quantum mechanics. The whole timeline splits into 2 just because of an atom rotates 2 ways at the same time. Or because someone could equally chose either outcome. That’s a stretch every part of it. With Schrodinger‘s cat an atom’s electron can’t possibly spin clockwise, and counterclockwise at the same time. If it could It would be the equivalent of someone turning their head left, and right at the same time, which it can’t be. One outcome can be 1 or the other, not split split into both. If you’re choice or an atom can spit the timeline prove it.

  16. physicists LIED… it's number 3 regarding this THING called life… And I've seen ALL the possibilities and remember~ unlike most… the problem is most don't remember living all the fast forwards and rewinds and parallels.

  17. Animated shows on TV could be in another universe, that means you could TECHNICALLY meet fictional TV characters lol.

    Think about it. If anything could happen in different universes, you could be making out with an orange bookshelf in front of a crowd of pink mosquitos and the mosquitoes could be singing a song about jelly pots.
    What has my life come to…

  18. Imagine infinite parallel multiverse exists. the main thing is that there's an infinite possibility of people on earth having the same versions of themselves in other planets and by "same" i mean they have infinite matches of people that have the exact skin wrinkles that they have or the number of bacterias in their groin when they were born exactly 15 minutes after birth. There's also an infinite possibility of people of my version do the exact same thing as i did throughout my whole life (eating bananas in an interval of 5 hours on a daily basis and drinking 7.12999 gallons of water every leap year). This concept of infinite parallel multiverse is so complicated and distorted that it almost makes me sick wondering all the possibilities that could happen in my head what the hell.

  19. I am from parallel universe and superheroes like avengers justice league countless more exist in my universe. It’s just in your reality we are “ fictional comic book character “

  20. every possible outcome. To note: not impossible outcomes. So there might be no universe in the infinite multiverse, where you date your celebrity crush (etc.). Infinite does not mean all options. Same as infinite numbers between 1 and 10 don't include 11.1111 or 234.100000001.

  21. I think two bubble observable universes collided and that’s why we have accidents because there were two possibilities. You dropped your ice cream by accident, and still you had a chance not dropping it, but you did drop it because things happen by random

  22. There is no way that there are infinite parallel universes because that would mean there would be a 99.9% chance that another parallel universe learned how to cross paralell universes… unless we are that unlucky 00.1%.

  23. Oh my, I'm that guy in the multiverse who is always gonna be single☹️.Hope my other forms in the parallel universe are doing good🙄

  24. So, before you read this comment, note that I am not religious. However, my religious friend recently told me about his belief in predestination about how doesn’t believe that God has made one universe, but almost like a chose your own path video game. That reminded me of the many worlds theory. As well as this, he explained how God exists outside of our realm of existence, that made me think about how if God existed he wouldn’t be third dimensional but a higher dimension, almost like the membrane theory. And then another interpretation of God is that he just exists where the world works differently, this made me think of the bubble theory. Now I am not religious and this hasn’t convinced me but it has convinced me that religious beliefs are an interpretation of quantum mechanics, as observed by the earlier humans.

  25. i love this theory but my only problem is if there is infinite universes then shouldnt there have been a universe that contacted us by now. either travel is impossible or its just a cool theory.

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