“When a spin is measured, the wave function branches via decoherence [according to the MWI], a single world splits into two and there are now two people where used to be just one. It makes no sense to ask which one is ‘really me.’ Likewise, before the branching happens, it makes no sense to wonder which branch ‘I’ will end up in. Both of them have every right to think of themselves as ‘me.’ [...] The world duplicates, and everything within the world goes along with it.”
In “Something Deeply Hidden: Quantum Worlds and the Emergence of Spacetime” by Sean Carroll
“Many-Worlds is the most falsifiable theory ever invented.”
In “Something Deeply Hidden: Quantum Worlds and the Emergence of Spacetime” by Sean Carroll
Let me get this out of the way first. Let me put forth the main 4 “interpretations”:
1 - "The particle travels through both slits: one in this universe and another which was generated because it had the possibility of going through both. Interference comes from the parallel universes interacting. (MWI)"
2 - "The particle goes through one slit, but it's guided by a pilot wave which goes through both and creates the interference. (Bohmian)"
3 - "The wave function has no definite position until it's measured, but measurement destroys the wave-like nature by forcing a collapse of some kind. (Copenhagen)"
4 - "Reality is subjective, so it doesn't make sense to talk about where the particle represented by the wave function is before measurement. (QBism)"
Now you have two choices. One, you pick your super favorite interpretation out of the four above, but be clear about what it explains trivially and what it leaves as crazy magic. Or two, you realize that without actual science to distinguish them, as I said in another post, these are all just idle thoughts to ponder while you shut up and calculate. I mean hell, we don’t even know that the one true interpretation has even been dreamed up and articulated yet.
If we apply Occam's Razor here, the MWI no longer looks like the neatest conclusion. In fact, once you throw in the fine-tuning problem of the Standard Model, the conclusion I draw from Occam's Razor is that all the interpretations are just blind shots in the dark; there's a much more fundamental process occurring which we don't understand because of insufficient experimental evidence. It could be string theory, it could be tiny turtles, or it could be something entirely different.
We actually are on figuring out if quantum states of quantum particles are affecting Neural Connections. Also decisions are pretty much made by bound Neural connections sending electric signals through them in an predetermined order which then in the end sends out a signal of what you do, think and so on. To that we are pretty sure that free will isn't a thing, but the product of saving and using information from the outside world:
Ice cream tastes good, but poop doesn't.
How do you know that poop doesn't taste good?
You've never eaten it. You smelled it.
And that smell turns into signals which are send through the whole brain to a few parts of it, into the memory for example. That memory is stored by creating multiple Neural connections which when seeing poop again, you know how it smells and thus can imagine the taste of it, too.
Same goes with thoughts of decisions, believes, opinions and so on.
And we are suspecting that the brain works in quantum levels, too. The many worlds interpretation seems to only work for two eigenstates with probabilities of 50/50 splitting into 2 universes. However anyone who's actually taken a course in Quantum knows that the probability of measuring either spin up or spin down depends on the wavefunction going in. The probabilities for each eigenvalue are almost never even, they could be split 60/40, 99/1 or any number of different combinations. Does that mean there's 99 universes for a measurement and 1 for the other. This gets even more complicated when dealing with an observable that has n eigenvalues. The Hamiltonian for the hydrogen atom theoretically can have an infinite number of energy levels, is there a universe for measuring every single one? Come on Carroll! Give!
The real distinction is not between different interpretations but two different approaches: realist and instrumental. People on the realist side need an interpretation like MWI or Bohm's pilot waves. They need them to justify their philosophical prejudices at the cost of abandoning scientific consistency. People on the instrumental side don't need any interpretation, just the framework for calculations. For some reason this framework is called by many people "Copenhagen interpretation" but in fact this "interpretation" is just a set of INSTRUMENTAL base concepts needed to do calculations. Some people define this approach using concepts of information theory (funny fact: Heisenberg did the same! For him wave function was all about information) while some others don't like to give particular names to concepts that are not useful, and describe this approach as "shut up and calculate". It's worth to notice that all realistic approaches to QM are in serious disagreement with modern particle physic, and with Occam's razor. I dunno, physicists spend lots of time thinking about issues that aren't covered in standard textbooks. I mean, that's the whole point of being a research scientist. I think part of it is that physicists don't see interpretational questions as affecting their research. But we do love hearing colloquia on fields besides our own, even if the results of these fields don't have immediate or obvious implications for our own work, so I think the shunning of foundations must have other reasons. I suspect it's an aversion to questions that cannot be empirically settled. Back in the day there weren't too much people who were interested in quantum mechanics but not doing real, genuine physics. Now there's plenty of them: philosophers, people interested in quantum computing, much more people doing non-relativistic (and non-innovative) QM etc. I'm deeply convinced that among the genuine quantum physicists (I mean people who really understand modern QM, especially Quantum Field Theories aka modern particle physics) the Copenhagen interpretation is dramatically more popular than the rest combined. I don't understand why almost no one talks about Bohm's pilot wave theory which is nothing but pure crack-pottery in the light of the current knowledge about particle physics...
In the mathematics of Hugh Everett’s many worlds theory the parallel universes or extra dimensions are at right angles to each other. In a process of spherical symmetry forming and breaking the mathematics can represent the surface of a sphere always being at right angles to the centre of the sphere. As a process of continuous energy exchange this can be seen in our everyday life with electromagnetic fields always being at right angles to each other. The reason why strings need extra dimensions and spheres only need three is because the two dimensional surface of a sphere can form a dynamic membrane or what I like to call a two dimensional boundary condition. In our everyday life this is represented by the movement of positive and negative charge with positive charge formed by the outer convexed curvature and negative charge formed by the inner concaved curvature. This dynamic two dimensional boundary condition allows the use of the holographic principle with the information of our three dimensional Universe encoded holographically with the movement of positive and negative charge. The other great advantage of having spheres instead of strings is that an interior of a sphere is naturally three dimensional.
The many worlds interpretation was designed to preserve determinism in the face of infinite uncertainty in quantum physics (i.e., probability wave function - double-slit experiment). The irony is that it has imploded under the weight of it's own declaration of determinism. It's logic has reacted to itself like it was it's own auto immune disease. MWI's "alternate worlds" conflict with it's deterministic foundations and it evaporated itself. Simply, if the universe was determined it wouldn't produce alternatives of itself. There wouldn't be probabilities in a determined universe to necessitate alternatives. Read David Albert's objections. It's all over but the yelling for the MWI. The math behind MWI is simply the extrapolation of the unrealized probabilities - what might have been... lol
It has always bothered me that in quantum mechanics we construct objects so as to obtain and use rigorous probabilistic description, while at the same in mathematics we can only say that probabilities "naturally" appear in quantum mechanics (because classical statistical physics is not really random). I'm glad to learn that probability professors refer to that vicious circle as a "scandal" as well. It cannot be stressed enough that "interpretations" is where we impose the arbitrary connections between reality and a self-contained mathematical theory. If we get rid of Probabilities in QM where does that that leave MWI? What if true randomness is deterministic? (As in Pascal's triangle.) It's unpredictable from within, but it's a simple mathematical function that generates everything.
If only more people understood the Transactional interpretation of quantum physics, which explains all the same things as Copenhagen, but doesn't come to the same ridiculous conclusion about "observation" being the trigger for wave-particles to collapse. Instead, you simply need to believe that there are particles that are so small and fast they can travel backwards through time. Since we already accept that if you travel at the speed of light, time freezes (from your perspective) it seems pretty logical that if you travel slightly faster, time moves backwards. Some people might say Transactional Interpretation is another ridiculous conclusion to the away to the wavefunction collapse...ROTFL! Sometimes I do too! That depends on the amount of beers I’ve already drank...How do you know it's not the quantum wave-particles that are making the choices, and the "decisions" you think you make aren't just a natural side-effect of those quantum processes? Even if I just agreed that one can "decide" stuff, how does that prove that billions of complete and nearly identical universes are spawned every second - as is required by multiverse theory? How does all the energy and matter required to make all these billions of universes just magically appear when required? Where are the other universes located compared to ours? Is there a universe where you aren't shit at science? So many questions and so little time for physicists like Carroll to answer!
This way of thinking is not only very likely deluded but is actually dangerous as at leads to an abstract view of things. Anyone else aware of Lee Smolin's recent theories about time which posit that time, rather than being an illusion as posited by Einstein and just about all physicists is a reality?
Carroll's book is pure rant to me. It replaces the usual confusion and mysticism about Copenhagen "observers" with confusion and mysticism about consciousness and bizarre claims that somehow being the leaf node in a tree of branching quantum events means you cannot trace back to your local root node. Which, from a computer science and math point-of-view is super silly. As silly as the dumb observer claims one usually hears when people misinterpret Copenhagen to mean that human observers cause the universe to exist or similar nonsense.
MWI fails to generate the known Born probabilities because it is bound into the number of branching wave evolutions, which are independent of the amplitudes - but the amplitudes squared are what gives the actual probabilities. I mean, MWI really does fail by any fair and honest accounting, even though proponents indulge sketchy and suspect runarounds like pretending that some worlds don't really count, and various mumbo jumbo. Haven't you thought about all that yet? I do have a version of MWI of my own in which 'probabilities' can be properly understood and as bonus can explain why we get the Hilbert space but that’s not something for this post. I think it is time for Carroll to start selling cars; he’d sell of a bunch of them in the blink of an eye. Everett must be having fun on the other side of the rainbow...
(*) Now, you ask me: “what interpretation do I believe in?” None of the four above.