Many-Worlds Leaves Basic Questions Unresolved

Many-worlds theory is nonsense from beginning to end. Here is an illustration.

Here is a new paper, from China:

oes the Universe Split Everywhere at Once? Rethinking Branching and Nonlocality in the Many-Worlds Interpretation of Quantum Mechanics

The many-worlds interpretation (MWI) of quantum mechanics, first pro- posed by Hugh Everett III in 1957, offers a radical solution to the measure- ment problem by positing that all possible outcomes of a quantum measure- ment occur in different worlds (Everett, 1957; Vaidman, 2021).

No, it does nothing to solve the measurement problem.

In quantum mechanics, the measurement problem is the problem of definite outcomes: quantum systems have superpositions but quantum measurements only give one definite result.[1][2]

The supposed solution is to say that all the other possibilities happen in unseen parallel worlds. But that does nothing to explain why we only see one definite result in our world.

While this interpretation avoids the need for wavefunction collapse, it introduces the contentious concept of branching — a process where the universe splits into multiple worlds whenever a quantum event occurs.

No, the wavefunction still collapses in our world. The rest of the wavefunction becomes inaccessible in our world, and related to only other worlds.

Over the past decades, the modern formulation of MWI has refined this idea, grounding branching in environmental-induced decoherence, a process that explains the emer- gence of stable, quasi-classical worlds (Wallace, 2012). However, critical questions remain unresolved: Is branching global, happening throughout the entire universe instantaneously (Sebens and Carroll, 2018; Ney, 2024), or is it local, propagating at finite speeds? (Wallace, 2012; McQueen and Vaid- man, 2019) How does nonlocality in entangled systems influence branching? Most importantly, can MWI reconcile its branching mechanism with the principles of special relativity?

With those questions unresolved, nothing is resolved. The theory has no substance.

It is amazing that trained physicists can promote this nonsense. And they complain that Pres. Trump might cut funding for it.

This paper draws its own goofy conclusions.

This paper aims to resolve key tensions by demonstrating that branching is neither strictly global nor purely local, but nonlocal for entangled systems. ... Crucially, this non- locality is apparent rather than fundamental. The multiverse as a whole retains a Lorentz-invariant structure, with no preferred Lorentz frame or superluminal influence across all worlds. This reconciles MWI with special relativity while preserving its capacity to explain quantum nonlocality.

Many-worlds is an esoteric subject, but even if you know nothing about it, it should be clear that physicists have been writing about it since 1957, and they have gotten nowhere. Nobody knows what the theory means, on any level. There is no agreement on anything. And no way to test the theory. It is nothing but an undefined fantasy.

In 1957, Everett said that if the whole universe is described by QM, then there should be a wavefunction for the universe. In particular, an observer would be included. So when an observer sees one outcome out of several possibilities, and it seems like a collapse of some local wavefunction, then presumably there is some way to interpret that collapse in the wavefunction of the universe. All that is clear enough. The weird part is making the leap to saying that the collapse is the creation of parallel universes.