# Sabine Hossenfelder explains the problem with the “many worlds” hypothesis

Sabine Hossenfelder, author of Lost in Math: How Beauty Leads Physics Astray, topic

The many world interpretation, now, supposedly does away with the problem of the quantum measurement and it does this by just saying there isn’t such a thing as wavefunction collapse. Instead, many worlds people say, every time you make a measurement, the universe splits into several parallel worlds, one for each possible measurement outcome. This universe splitting is also sometimes called branching.

Some people have a problem with the branching because it’s not clear just exactly when or where it should take place, but I do not think this is a serious problem, it’s just a matter of definition. No, the real problem is that after throwing out the measurement postulate, the many worlds interpretation needs another assumption, that brings the measurement problem back.

The reason is this. In the many worlds interpretation, if you set up a detector for a measurement, then the detector will also split into several universes. Therefore, if you just ask “what will the detector measure”, then the answer is “The detector will measure anything that’s possible with probability 1.”

This, of course, is not what we observe. We observe only one measurement outcome.

Sabine Hossenfelder, “The Trouble with Many Worlds” at BackRe(Action)

They end up with all the same problems in this universe plus infinite universes as well. But some may want that.

and

Sabine Hossenfelder: The multiverse is a fringe idea

## 3 Replies to “Sabine Hossenfelder explains the problem with the “many worlds” hypothesis”

1. 1
Somerschool says:

I don’t quite understand her argument, I am afraid. Does anybody else want to explain it to me?

2. 2
Eugene says:

We don’t know what “making a measurement” even means at the fundamental level. If one is to assume that consciousness is not involved in collapsing the wavefunction, and that wavefunction does not really ever collapse (which I believe was the main premise of the Many Worlds) then I guess we would have to allow for the universe to keep splitting each and every time when 2 wavefunctions meet each other and thus become entangled…? The latter presumably happens a lot more often that us making any “measurements”.
…Wavefunctions are truly weird. As someone was saying, “nature is trying to tell us something here”, and we are doing our collective best to not listen to it. Because materialism.

3. 3
OLV says:

Modern physics seems to be discrediting itself with so much nonsense being presented as rational arguments.
This continuous speculation going on in theoretical physics these days doesn’t seem to help us answer fundamental questions in biology evo-devo : where did the biological cell get the centrioles, centrosome, spindle assembly checkpoint, kinetochore, cytokinesis, and all that stuff working together in such a marvelous choreography? Biology -where WYSIWYG is the bottom line research principle- is becoming the king of science, rendering the other scientific domains -math, physics, chemistry- its submissive servants. Humpty Dumpty has become the spokesperson of the biological cell. But the world still hasn’t noticed any of that yet. Oh well, what else is new?