I have no idea why this theory is so popular in science. It’s faddish and utterly ridiculous.
If the Many Worlds Interpretation is true, that means that there’s a universe exactly like this one except one morning I chose to eat English muffins instead of toast for breakfast.
It means there’s a Universe where I’m married to Cheryl Cole (take me there pls?) and where Jim Carrey is president of the United States.
I have no problem accepting alternative universes in the sense of other physical realms aside from our own universe, but the idea our history and universe is just one of an infinite number of copies is ridiculous. It’s nothing but mathematical masturbation.
Yeah, I first ran into the idea with Flash comics #123, Flash of Two Worlds, 1961. I was eight at the time, and had no idea anyone would ever take it for real science. Everything I’ve read (which, admittedly, is at a beginner layman’s level) makes it sound slightly more screwy than string theory (which I also have trouble getting my mind around).
Doesn’t mean it’s wrong, though…
Larry Niven wrote a short story about this, called All the Myriad Ways (Free e-text HERE). The gist of it is that this model is proven to be true, and people quietly go nuts, thinking that nothing they do has any significance, seeing as it doesn’t make any difference whether you do something or not.
I’m not a fan of Many Worlds either, but I think part of your problem is that you misunderstand the idea. It’s the idea that all possible paths are followed, but from that doesn’t necessarily follow that everything that you could imagine would necessarily exist in the multiverse.
Personally, I’m not a fan because it seems to jump from “we don’t understand uncertainty” to “let’s explain why we can’t understand it”. It’s gotten popularity, I think, largely because the concept of parallel universes is fascinating and once it gets some sort of footing in reality, even a shakey one, it’ll get latched onto. It’s not terribly unlike how the idea that black holes distort space and time, therefore flying a space ship into one makes it a wormhole or a time machine or whatever in popular science fiction.
I’d rather hope that, one day, we’ll come to understand these principles in a, perhaps more mundane, but ultimately more elegant way.
I think the many-worlds interpretation of quantum mechanics is incredibly pointless and stupid. It’s not quite what you described in your OP: the idea is that every time a probabilistic quantum interaction occurs (where there is no way to predict the outcome beforehand) that all possible outcomes actually take place in separate universes. It’s a thought experiment designed to build something resembling determinism into inherently non-deterministic processes. Why anyone would find the thought of infinite universes containing all branches of microscopic interaction configurations more palatable than one universe where we traverse a single arbitrary set of those outcomes is beyond me. If nothing else, it gives stoners something to talk about between Simpsons reruns.
It IS a theoretical physics concept, so there you go.
I don’t have a problem with it- like Blaster Master said, it’s a situation where all possible paths are followed. I take that to mean that at each decision point, a “universe” is created for each of the options, where you took that option.
So for example, in my own life, there was a point when I decided to go to Texas A&M instead of the University of Texas. According to this theory, there’s another “universe” out there where I chose the opposite way and went to UT.
It’s all theoretical; I don’t really think that it means that there’s another earth, etc… more like there is/was a mathematical function describing the probabilities of things that might happen down a particular path.
Imagine it this way… you’re writing a really big book. At each decision that a particular character makes, you write the outcome of each choice.
We’re just interacting with a particular choice down that tree, or at least that’s how I understand it.
It’s my understanding that the many-worlds idea doesn’t really bear a lot of resemblance to the sci-fi trope of finding oneself in a world where Al Gore was president or the south won the civil war. It’s more what Giraffe said above, a way to deal with the measurement problem. It’s also my understanding that every other attempt to understand the measurement problem also leads to seemingly absurd results, though they are more subtle than a vast number of other universes. Also, it doesn’t seem like it’s something physicists really worry about, since the phenomena do what they do regardless of what interpretation a particular scientist uses. This annoys me, but there we are.
ETA: Bump I don’t think your decision to go to one university or another is the kind of event the many worlds hypothesis deals with. It’s more about photons being emitted or absorbed, particles being spin up or spin down, etc.
Again, no expert, I’m sure I’m getting a lot wrong here.
It would still imply that just about every history you could imagine actually exists somewhere, barring those that violate physics of course. If many world hypothesis is true, there is indeed a version of me and a version of Cheryl Cole married somewhere. As unlikely as it is Cheryl would go for someone as broke, overweight and white as myself, a wedding between us is within the realm of the physically possible unlike Harry Potter or something.
In a world where an infinite number of possibilities was realized or at least close to it, there would not only be one universe where we were married but possibly an infinite number, since a fraction of infinity is still infinity.
If there’s a finite amount of matter and it’s been a finite time since events began, then there’s still a finite number of universes even if the number doubles everytime there’s two ways a measured thing could go (the splitting perceived as a collapse of the probability field into the specific result, in the “other” universe created, same perception of collapse, opposite result).
Really immensely huge finite number, but finite. 2 raised to a huge finite number is another much huger finite number.
In this very large finite number of theoretical universes, there is no guarantee that any such path through possibility would lead to a person recognizable as a version of you married to a person recognizable as a version of Cheryl Cole. And I don’t know how you’d go about tracing whether there was a path of events that could have led to that result or not.
If the very most basic random events are always a 50/50 chance, that makes this interpretation seem more likely. If there exist random events that can’t be broken into smaller 50/50 probability events, the theory may need revision to have any chance to apply.
I’m not saying there is only one planet with life or even one universe. I just think the idea there are copies of this universe that are exactly the same except for a tiny difference defies logic.
Of course just because something is strange doesn’t mean it’s not true.I think many-worlds reflects our contemporary “whateverist” postmodern culture more than it’s a likely possibility. The fact it’s impossible to verify empirically since these universes are said to be impossible to contact is convenient too.
MWH says more about our culture than it suggests anything about our reality. I think it’s at its core, a very nihilist theory since if this is just one of an infinite number of copy universes nothing we do is really special or matters. I also think it’s connected to our contemporary admiration of pluralism as opposed to having strong values.
It’s not quite that simplistic. If all that were to explain was mere indeterminism, physicists would by and large shrug and say, ‘so things happen by chance; what’s the big deal?’. The problem is that the dynamics of quantum mechanics explicitly don’t allow for the kinds of things we see happen in measurements, meaning that we have to describe the world with two mutually incompatible processes: one is the regular unitary or Schrödinger evolution of the wave function, and the other is the reduction or collapse of the wave function.
The problem is that the Schrödinger evolution naturally leads systems to develop into superpositions, i.e. states that are neither determinately one thing nor another. But if we then measure this state, we never find such a confusing jumble, but always a nicely definite state (which one albeit being a question of chance). Nevertheless, we can detect the effects of systems being in superposed states at least in an indirect manner—one such indirect effect is entanglement, for instance.
And even all of this would not be problematic if there were just some special sort of interaction that is a ‘measurement’, or some special class of systems that enact such measurements, so that we could say, ‘whenever two systems interact in this-and-that way, that’s a measurement, and reduction occurs’. But there is no operational way to tell measurements apart from other interactions: what is used as a measurement in one setting, collapsing the wave function, needs to be described by the usual Schrödinger dynamics in another.
So things are in kind of a muddle when it comes to measurement. Many solutions have been proposed, but few ever gained any kind of traction. Everett’s solution is perhaps one of the most radical: just get rid of the collapse process, and have the Schrödinger dynamics reign absolute. Then, in order to explain why we never observe any superposition, he introduced the notion of a ‘relative state’: some quantum property, say the spin of an electron pointing a certain way, is only definite relative to another, correlated one—typically the state of a measurement apparatus. So we have the electron spin being ‘up’ relative to the detector detecting ‘spin up’, and the electron spin being ‘down’ relative to the detector detecting ‘spin down’.
However, he wasn’t really all that clear about how to make sense of these relative states; in fact, within the interpretation of quantum mechanics, there’s basically a whole subfield devoted to interpreting Everett’s interpretation. One possibility here is the ‘many worlds’-idea, which I think is largely due to Bryce DeWitt: each of these relative states defines, in some sense, its own world.
And that’s where we got this from; it’s not that simply some process has a random outcome, and somebody thought, ‘hey dude, what if all those outcomes actually happen, like, somewhere?’.
(But nevertheless, I should mention that the ‘many worlds’ reading of Everett has in some circles, notably among philosophers of science, acquired the moniker ‘the vulgar interpretation of quantum mechanics’. Myself, I think it’s a too simplistic reading, but the discussion would only take us further afield…)
Another good one and no doubt inspired by Niven is Robert Charles Wilson’s Divided By Infinity which you can read here. It further explores MW hypothesis and Quantum Immortality and reaches some rather disturbing conclusions.
I don’t agree that these are mutually incompatible. Quantum mechanics says that systems are allowed to straddle the fence as long as both sides are for all intents and purpose the same, but that once anyone else would notice a difference between being on one side or another they have to pick one. Pauli exclusion, Hund’s rules, spin conservation: whatever your constraint is, you can ignore it as long as no one can tell you haven’t satisfied it. Once the outcome of an interaction would be different depending on which state you’re in, the mixed state is no longer possible and the system randomly falls back into one of the underlying pure states.
The fact that mixed states can form and lead to measurably different outcomes (e.g. the two-slit experiment) is pretty amazing when you think about it; it’s the weird part of the whole thing, not collapse. Many worlds is throwing an unnecessary layer of philosophy on top of a well-defined theory that adds nothing meaningful beyond trying to wish away an aspect of nature one finds troubling.