Quantum Theory reveals Parallel Universes and Quantum Immortality in alternate universes

imagine a universe where you're as rich as Bill Gates you're married to Kate Upton and you're as admired as Oprah Winfrey what if I told you that there may be a parallel universe where all these things are true about you many people dismiss the idea of parallel universes because they think that since by definition we can't see them they must be like the Bigfoot monster they may exist in theory but they're probably dumped but parallel universes are not a theory they're predictions from theories that are widely embraced by physicists what is the evidence for alternative universes and could different versions of us exist in parallel somewhere out there that's coming up right now alternate universes are predicted by a couple of theories for example string theory has ten dimensions and by some estimates up to 10 to the 500 solutions if this theory is true then all those 10 to the 500 solutions would potentially have a universe attached to them we just happen to be living in this one universe but in this case all of the alternate universes would have completely different properties than our universe and in most of them life would probably not exist so these would not be parallel universes where different versions of us could exist but there are two other theories that predict not alternate universes but parallel universes where the universes are just like ours but only slightly different where different versions of us could exist one is the idea of infinite universes science doesn't know how big space actually is the reason it appears to be only 13.7 billion light years and radius is because that limit is set by the distance that light has had the ability to travel since the instant of the Big Bang but this does not mean that there isn't more universe out there beyond the portion that's visible to us the universe is likely larger and perhaps infinitely large if space is infinite then it must start repeating at some point because there's only a finite number of ways that any set of particles can be arranged physicist Brian Greene calculated this number to be 10 to the 10 to the 120 to now this is a very very large number but it's still minuscule compared to infinity so if you travel far enough in space you should see another version of you living in completely different circumstances perhaps as president of the United States or as rich as Bill Gates but the most intriguing theory that leads to parallel universes is one that is embraced by some of the biggest names in physics including Max tegmark Brian Greene Alan Guth and Sean Carroll and this idea of parallel universes comes from the many-worlds interpretation of quantum mechanics according to the laws of quantum mechanics all particles are in superposition meaning they exist as waves of probabilities in multiple states and multiple locations at once they only gain distinct properties and location when they are measured the many-worlds interpretation was proposed by Hugh Everett for his PhD thesis in 1957 at Princeton University this theory says that the probability wave never collapses that every time a wave seemingly collapses in our universe there is a parallel universe where no such collapse happens this interpretation implies that reality splits like a fork in the road in effect this implies that the entire universe is one gigantic wave function that contains all possible realities ever it even called this the universal wavefunction and his thesis so the universe is also in superposition of all possible States of its constituent particles and as it evolves some of these super positions break down making certain realities or worlds distinct and isolated from each other to be clear the many-worlds interpretation doesn't exactly predict other universes in the way that scientific theories make predictions this is just deduced from the hypothesis that a wavefunction collapse does not occur in other realities the many-worlds interpretation avoids the complication of wavefunction collapse but it creates the seeming complication of a near infinite number of whorls this seems to be a fantastical idea that there's a universe out there for every outcome that you can possibly conceive just like in quantum mechanics everything with a nonzero probability of occurring is a reality somewhere in some universe in other words there's a universe out there where everything happened just like it did in this one except you made one or two decisions differently and your life turned out completely differently like you became as rich as Bill Gates or married Kate Upton Bryce DeWitt who popularized the many-worlds interpretation in the 1970s says every quantum transition taking place at every star in every galaxy in every remote corner of the universe is splitting our local world on earth into a myriad of copies very bold claims like this requires some old evidence so we have to ask some questions like okay how does a split actually happen well this is the crazy thing about the interpretation it says that the splitting occurs whenever a wave collapses meaning whenever a measurement or observation occurs so this would mean that when you walk around in your own house there must be millions of splitting events because molecules and your feet are interacting with the molecules on the floor the number of splits and parallel universes has to be astronomical some physicists consider this almost self-evidently absurd but others like Oxford physicists David Deutsch says many-worlds is virtually a fact it is no more an interpretation than dinosaurs are an interpretation of the fossil record and even though the results sound fantastic the many-worlds interpretation predicts outcomes that are completely consistent with physics experiments over the course of decades so it has to be taken seriously even though it sounds ridiculous and I have to say that for me to the idea of billions or trillions of world is not aesthetically pleasing but I can't reject the theory just because it doesn't satisfy my intuitions I have no vote on how the universe should work but one of the most serious difficulties with multiple worlds is what it does to the notion of self MIT physicist Max tegmark says the act of making a decision causes a person to split into multiple copies but what does it mean to say that splittings generate copies of me in what sense are those copies mean I have no awareness of the other copies Columbia University professor Brian Greene says we just need to broaden our minds of what self actually means each copy believes that it is you the real you is the sum total of all the splittings he says but physicist and philosopher David Wallace says that the notion of the eye can only make sense if once consciousness is confined to a single branch of the quantum multiverse reality but there's no physics that could explain that if your consciousness or awareness of you were somehow able to sneak along just one path of the quantum multiverse as Wallace says then we'd have to regard it as some non-physical entity immune to the laws of physics so how could we ever know if the many worlds theory is correct in the late 1990s a thought experiment was proposed by MIT physicist max tegmark called quantum suicide this is similar to the schrödinger's cat experiment and an analogous experiment would go something like this let's say you're participating in a wager you were put in a box with a gun pointed to your head and a button in your hand the button controls a quantum splitter that detects the spin of an electron if after you press the button the spin says up the gun does not fire you've come out of the box and went the prize of a billion dollars but if the spin shows down then the gun fires and you die instantly there's a 50% chance that the splitter would detect up and 50% that it would detect down the question is would you take this bet few people would I think would accept the 50/50 odds of life and death but I might take this bet and here's why if you truly believe in the concept of multiple worlds then you would take this bed every time because the only one of you that would ever come out of that box would be the one that remains conscious in other words in your world for you to be conscious you would always have to be the reality that survived in another world the other use would be dead but you would not know this your conscious self would always survive and become a billionaire the bottom line is this in the many worlds interpretation all outcomes with a nonzero probability have a 100% chance of occurring in a parallel universe your consciousness always survives in some world so therefore you will always survive the Box wager because the survival of your awareness depends on your not being dead but obviously we cannot test the multiple worlds theory in this way so how do we test for these parallel universes max tegmark says we can test this by studying quantum mechanics and building quantum computers if a quantum computer fails and we learn that fundamentally the equations of quantum mechanics are wrong then these parallel universes don't exist but if we can build quantum computers and quantum mechanics equations are proven true that we have to take it seriously no matter how aesthetically unpleasing it seems our vinash here if you liked our videos and consider subscribing and ring the bell so that you can be informed when we upload more fascinating videos we make one to two videos a week we'll see you in the next video [Music]