Many Worlds Theory: A theory devoid of meaning, goals and purpose

Many Worlds Theory: According to this notion, every time a fundamental particles goes in more than one direction at once whole universes (and Earths) come into existence to accompany its multiplication!

I thought I would offer a few thoughts on the following quotes from Sean Carroll which I published in my last post.

The Many-Worlds formulation of quantum mechanics removes once and for all any mystery about the measurement process and collapse of the wave function. We don’t need special rules about making an observation: all that happens is that the wave function keeps chugging along in accordance with the Schrödinger equation. And there’s nothing special about what constitutes ‘a measurement’ or ‘an observer’ – a measurement is any interaction that causes a quantum system to become entangled with the environment, creating a branching into separate worlds, and an observer is any system that brings about such an interaction. Consciousness, in particular, has nothing to do with it. The ‘observer’ could be an earthworm, a microscope or a rock. There’s not even anything special about macroscopic systems, other than the fact that they can’t help but interact and become entangled with the environment. The price we pay for such a powerful and simple unification of quantum dynamics is a large number of separate worlds.

Sean Carroll, “Splitting the Universe: Hugh Everett blew up quantum mechanics with his Many-Worlds theory in the 1950s. Physics is only just catching up” at Aeon

….the Many-Worlds perspective, while not making much sense in other approaches to quantum foundations. Niels Bohr might have won the public-relations race in the 20th century, but Hugh Everett appears ready to pull ahead in the 21st.

Sean Carroll, “Splitting the Universe: Hugh Everett blew up quantum mechanics with his Many-Worlds theory in the 1950s. Physics is only just catching up” at Aeon

Here's an example of the sort of thing Carroll is talking about:

Imagine we are in Earth orbit and we have a particle detector that is detecting radiation from deep space and then along comes a deep space particle: Because we are dealing with quantum mechanics and not classical theory this particle arrives in the form of a wave packet. Moreover, this wave packet is subject to dispersion; that is, the wave packet spreads and it spreads linearly with time. This dispersing wave packet represents a multitude of possible microscopic worlds in that it symbolises many particles spread over many positions; as Young's slits experiment suggests, particles are capable of moving off in several directions at once. Now, as Carroll says this wave packet may happen to impact a macroscopic object like, say, a humanly constructed detecting machine which has the potential to magnify a particle detection event up to macroscopic scales. (I am inclined to agree with Carroll that we need not necessarily be talking about a conscious detector such as a human being). If the detection device happens to be in a universe where the the incoming particle is located at the point of detection and triggers a detection event then the presence of the particle, because of the amplifying properties of the detector, will have a macroscopic outcome. But it is also possible that the detector is in one of the many universes where the particle isn't found at the point of detection and therefore in these universes there is no  macroscopic detection event. Now in multiverse theory both these events happen so that at least one of the universes registers a detection event whereas all the other universes that have the particle at an entirely different position will have unaffected detectors. The point is that in multiverse theory the macroscopic world, as well as the microscopic world, are multiplying. Because among these possible worlds randomness of detection has such a high statistical weight, then probability calculus will describe the detection events for the observers in by far and away the greatest number of universes. Otherwise it is important to note that the multiverse as a whole is entirely deterministic.

In this many worlds theory the wave packet doesn't collapse; it only appears to collapse in the universe where a macroscopic detection event has taken place; it is a perspective affect only seen in the detecting universes. All the other universes where no detections take place will continue on their histories where their detectors are unaffected. I suppose I have to grudgingly admit that Carroll does have a possible (if to my mind implausible) interpretation especially as his views (currently) make absolutely no observable difference and cannot therefore be tested.

One theory that doesn't work, however, is the decoherence explanation of quantum collapse. Because this particle comes from deep space it could have been travelling for millions of years and over the course of time the wave packet may be spread over a huge volume of space. Although interaction with the matter of space might have help keep the packet more condensed than it otherwise would have been, it is likely at least some deep space particles are spread over at least several light hours, if not light years.  This huge spreading of the wave packet rules out the decoherence concept of wave-function collapse because for a wave packet spread over a huge volume collapse due to the deterministic interactions of decoherence cannot take place except over a large period of time. This, I believe, is not observed; actual collapse is all but instantaneous.

For Carroll the many worlds view is his preferred world view because it doesn't introduce any complicating and enigmatic extras about a real "collapse", extras that would require hypothesis and explanation; For example, he doesn't need to define some seemingly arbitrary distinction between the macroscopic and the microscopic or posit the instantaneous and random action at a distance necessary for the discontinuous leaps of the quantum state vector. Carroll does away with all that in a swoop. For him the only intellectual overhead is the positing of a large number of separate worlds and he clearly has little problem in accepting such. (Or does he? He does look a little bit apologetic about it!) But I wonder if people are really aware of how large is large? For every particle represented by the smeared out wave packet there exists a corresponding universe; one doesn't have to wait for a macroscopic detection event before the macroscopic universe starts multiplying; there are as many macroscopic worlds as there are fundamental particle configurations: it's just that chaotic sensitivity  of our physical regime means that some of these macroscopic universes follow very differ macroscopic histories.

For me this is all very pointless and meaningless: Many worlds is selecting out nothing; it allows everything through. It is utterly indiscriminating and even handed. It's an obsessive symmetry gone mad.  For Carroll this doesn't matter; the cosmos need have no meaning at all.  He's more concerned that we don't have the inconvenience of having to introduce extra rules and laws explaining macroscopic detection events. Moreover in the bigger picture of the multiverse Carroll does away with the contingency of randomness, for in the multiverse that randomness is just a perspective affect. I suppose it's different strokes for different folks. Or is it? People have a way of insisting that their line of thinking be adhered to by others on pain of being insulted or even by applying duress of some form or other! For an example of that we need look no further than fundamentalist theme park boss Ken Ham.