1. ### I Binomial distribution of "worlds" in MWI

If we have a spin measurement with P(up)=0.5 en P(down)=0.5, this is equivalent to tossing a coin P(heads)=0.5 and P(tails)=0.5. The probability of having five heads and five tails out of ten tosses is the binomial: ##\binom{10}{5}(0.5)^5(0.5)^5##. So the same would hold for the spin...
2. ### I Compatibility of MWI with probability of outcomes

Can MWI account for the probabilities of outcomes? If MWI says all outcomes are realized, is the probability that an outcome occurs then not 100%? How is this explained with the entanglement of the measured object and the measurement apparatus?
3. ### I Observer superposition in MWI?

In MWI, would you say that a measurement puts the observer in superposition of being in the various worldlines? If I said "yes" to that, would I be correct?
4. ### I Does MWI say this?

Does MWI just say that everyone agrees about what the pointer of the measurement apparatus shows?
5. ### I Superposition of branches in MWI

So I consider a measurement on a superposition, in MWI, leads to another superposition: ##(|A\rangle+|B\rangle)|Observer\rangle \rightarrow |A\rangle|Observer{A}\rangle+|B\rangle|Observer{B}\rangle## If we come to the latter situation, a superposition of branches, why does that not mean that...
6. ### Is the past in MWI unambiguous?

I couldn't match this question with another topic, so I made a new topic. Suppose we have past H and present P at a certain moment. In present P a measurement is made. For matter of speaking we adopt MWI, so we have the two measurement outcomes A and B diverging in two realities A and B in...
7. ### Counterfactual Definiteness and MWI in Wiki

Summary: Counterfactual Definitiveness and Many World's Interpretation Sorry for all these threads, my noetic fluids and bursting. Wiki states the following: In quantum mechanics, counterfactual definiteness (CFD) is the ability to speak "meaningfully" of the definiteness of the results of...
8. ### I On what plane of existence do quantum computations occur?

I was recommended by another mentor to purchase a good book on MWI, which I think should be a thread or poll of its own. Anyway, I might have debased myself too much in that other topic, as I understand on an abstract level how QM works. In my own words, I feel as though possible worlds are...
9. ### I The reality of "Many Worlds"

If MWI and collapse-theory are both possible interpretations of QM, then both of them are not a fact, right? If MWI is a fact then collapse isn't and vice versa, you could say the least. So, shut up and calculate, i.e. the minimal interpretation, makes no inference about the realness of these...
10. ### I Is QM causal/deterministic?

Is QM causal? Specifically, is it time reversable? Does that equate determinism? Specifically, in the case of MWI? Edit: Is QM deterministic? Specifically, in the case of MWI? Is it time reversable?
11. ### I Reality and MWI

Could MWI signify that there are not necessarily a (near) infinite number of real worlds, but rather that officially we can't tell if, or to what degree, the world we are in is real?
12. ### I In which cases does superposition lead to splitting of worlds?

I don't know how to understand this: Suppose we measure the spin of an electron with apparatus M. M can yield spin-up or spin-down. According to MWI, M briefly becomes in superposition of measuring spin up and spin down. Extremely quick however, M gets split by the splitting into two universes...
13. ### I MWI experience of created worlds

Would this be correct: in MWI, if a binary measurement is made, the world splits, say in world A and B. Is it then correct to say that you experience both A and B, but that the experiences of A and B become separated?
14. ### I MWI -- Infinite number of worlds?

If we would, for sake of argument, adopt the MWI interpretation, then are there wavefunctions (like for instance position) that have a continuous probability spectrum, and will MWI then propose that there are an infinite number of actual universes that each represent a position in that...
15. ### I Conservation of possibility?

Suppose we have a quantum object in superposition to some measurement basis, given by: ##\frac{\sqrt{2}}{\sqrt{3}}|a \rangle + \frac{1}{\sqrt{3}}|b \rangle##. (1) Suppose the measurement is made, and the system evolves, according to MWI, into ##\frac{\sqrt{2}}{\sqrt{3}}|a \rangle|W_a \rangle +...
16. ### I The (quantum) world existing AND non-existing

Can we suppose that a quantum property (like spin, polarisation, velocity, position) becomes a potential, a probability, when we are going to measure it? Can we say that this property does not exist while remaining unmeasured, and that when measured takes on a value that depends on both the...
17. ### B Do worlds of MWI ontologically have to exist?

Is MWI equivalent to a superposition of possible Collapse-worlds? That is, is it equal to a superposition of the possible scenario's given by Collapse Interpretation? Is it imparative that the "worlds" given by MWI all ontologically exist?
18. ### I World selection in case of entanglement measurement

Suppose we have a pair of spin entangled electrons, measured by resp. Alice and Bob. The basises of Alice and Bob make an angle of α=10°. If Alice and Bob wind up in a joint world where Alice measures ##|u\rangle##, then the probability that, in that world, Bob measures ##|d\rangle## is...
19. ### I Is the math for collapse int different than for mwi?

Because I understand that for unitary evolution, MWI is required, which suggests that for different interpretations, there may not be unitary evolution?
20. ### B Simple question about MWI superposition

I am sorry to bore you people with a very, very simple question (there is no catch unless QM throws it :nb) ): ?:) If we have a half silvered mirror and we fire a single photon at it at an angle of 45°, it either passes or reflects from the mirror. To be more precise, the photon becomes in a...
21. P

### I Some questions about time and causality in the MWI

Forgive my novice question; but, how does one explain the fact that decoherence doesn't contradict the evolution of the wavefunction in every world? Meaning, how is causality preserved in each world and what concept of time is professed wrt. to each world in the MWI? In other words, it seems...
22. ### I Probabilty of many world viewing.

I believe that anything is possible. If technology became so advanced, that it was suddenly possible to peer into any of the other worlds (in the infinite number of many worlds suggested by MWI) and see what was happening. What do you think we would see? What technology would be needed? What...
23. ### I Does MWI imply solipsism?

Hi guys, I am new to physics forums and am an undergrad who is really interested in the philosophical implications of quantum physics. I know this isn’t a philosophy forum but upon skimming older threads regarding MWI I have come across an interesting number of posts by a few members named...
24. ### I On being the sole observer in MWI

Hi all, Suppose we have some particle in state $$|\Psi\rangle=\frac{1}{\sqrt{2}} (|U\rangle + |D\rangle)$$ It starts interacting with its environment, including Experimenter 1 (E1). From Experimenter 2's viewpoint, this can be represented as: |\Psi\rangle=\frac{1}{\sqrt{2}} (|U\rangle...
25. ### I MWI for simultaneous events

Suppose there are two independent experiments taking place \left\vert \Phi\right\rangle =\alpha _{1}\left\vert \phi _{1}\right\rangle +\beta_{1}\left\vert \phi _{2}\right\rangle and \left\vert \Psi \right\rangle=\alpha _{2}\left\vert \psi _{1}\right\rangle +\beta _{2}\left\vert...
26. ### I QM Ignorance is Bliss

The purpose of this post is to describe what may be a useful way of viewing some aspects of QM. It probably doesn't rise to the point of a testable theory. Over a year ago I argued against the Many Worlds Interpretation based on quantum conservation of information. My argument was this: Any...
27. ### B What is the difference between MWI and CI?

Suppose we measure a normalized state ##|\Psi \rangle = \alpha _0 | \lambda _0 \rangle + \alpha _1 | \lambda _1 \rangle + \alpha _2 | \lambda _2 \rangle + ...## with ##| \lambda _i \rangle## the eigenvalues of the measured observable. Is it true that, in the CI, the wavefunction collapses into...
28. ### CI vs MWI - contradictory?

Suppose we fire a photon P at a polarisation filter F1, and it passes the filter, thus forcing the polarisation of P in an eigenstate M1. Subsequently, the photon falls through a polarisation filter F2, forcing P in eigenstate M2. Now, if I understand correctly, the probability of P passing F2...
29. ### Many Worlds Interpretation and act of measuring

"We can’t make a measurement without influencing what we measure. before we look, there are only probabilities. When we open the box, they give way to a single actuality" It would be more like this, all the time, Until we look...