We aren't told its both, we are told it has properties of both, and even in the multiverse theory it still has properties of both. It still acts as a wave it merely diffracts with a "particle" from another universe rather than itself.
I think that is the point of the multiverse theory, in that the duality explanation seems somewhat of a copout. It is used to provide an explanation for a behaviour of a particle which appears to be neither entirely a wave nor a particle but exhibits characteristics of both. So we are told that it is both - if you think about it, it is no harder to believe this than the multiverse theory
I really don't see how its a cop out, multiverse theory is interesting and captures the public imagination a lot but the majority view still sides with standard wave-particle duality.
You are imagining particles to be little balls that is where your problem lies, if you accept "particles" are not little balls that infact they are nothing like little balls, there ceases to be a problem.
Remember particles have been proven to just disapear from one point in our universe and reappear in another point. So where was it inbetween?
Not really, because you can get a diffraction pattern with "one" normal wave (like sound or a water wave) in exactly the same way, waves split when they hit multiple slits.
But doesn't it strike you as odd that even a single "wavicle" can produce an interferance pattern when this is caused by two waves interacting and cancelling each other out in certain areas?
The wavefunction does exactly the same thing, the wave function is a waveform which governs the probability of finding the "particle" at any point.
I don't see a problem.
That is where the duality is a problem.
Balls only bounce when they are dropped, the observed charactertistics of an object are often linked to circumstance, in different (but speicific) circumstances different characteristics of a "particle" are observed.
The particles are only waves while many are being sent,
And single "particles" still act as waves, whether they be a single photon or electron producing a diffraction pattern or the electron in the orbital of a hydrogen atom.
You can choose to add in the "but their interacting with stuff from other universes", but you don't necessarily need to.
"Particles"are never ever little balls, they are always objects with wave-like and of particle-like properties: Sometimes they are seen to act like waves, and sometimes they are seen to act like little balls.
and when you sending a single one at a time they are particles.
We humans dislike this idea because there is nothing on our scale of perception that matches this behaviour, our brains have evolved to comprehend a world with ranges between grains of sand and mountains, and so things in that range are intuitive and "make sense".
Its only been taken up (and its not actually used in the literature very much its just used when attempting to explain some of the ideas in quantum mechanics) as terminology because our traditional concept of particles is fundamentally flawed in light of quantum mechanics.
Wavicles are an idea that was created to explain an almost unexplainable dilema - but like many of Newtons theories,
There is not necessarily a problem with what we are seeing, that doesn't mean that there isn't more to it, multi-universe theory might turn out to be right, BUT it doesn't have to be, the current explanation could be correct, the mainstream view is still that it is.
they'll do for now, but they are not perfect as our understanding of physics hasn't matured enough to fully udnerstand the implications of what we are seeing