Stop destroying reality, Alice

Wow, blogging has really hit a dead zone of late, hasn't it ? Two main reasons for that. First, my long-awaited Oculus Quest arrived, and it's as awesome as I was hoping for. So quite a lot of my free time is now happily given to exploring strange new worlds and weird civilizations. Second, I'm deep in a recoding project which is going well. Normally I'm happy to break up my workday by reading random stuff and blogging up anything I think worth summarising and/or commenting on, but I don't like doing this when concentrating on code : it's too disruptive and takes too long to get back into the flow. Hence the blogging front has taken a backseat of late.

Not that this has stopped me reading stuff on my phone from time to time though. Lately my news feed has decided I need to learn about quantum paradoxes for some reason, which frankly was getting confusing until I found the one embedded below from Ars Technica. Other articles have much more complex descriptions, but I found this one much easier to follow. So let's resume the blogging with a classic long-term topic : the nature of reality.

Wigner grabs his friend, Alice, and places her in a sealed laboratory*. Alice measures the spin of a stream of electrons that are prepared in a superposition state. Wigner is outside the laboratory and will measure the entire laboratory. Alice, before passing out, determines that an electron is spin-up. But Wigner hasn’t made a measurement, so he sees Alice in a superposition of having measured spin-up or spin-down. When Wigner makes his measurement, hypothetically, he could end up with a result where Alice measured spin-down when in fact she measured spin-up. 

Two “facts” contradict each other, but both are based on reality. Wigner’s solution to this problem was that the quantum state cannot exist at the level of the observer: the superposition state must collapse before that occurs.

* Wigner is, of course, subsequently sued and made to watch the tea consent video multiple times.

If I understand this correctly, in essence Wigner "measures" Alice as having not taken any measurement, whereas Alice herself is quite sure that she damn well did take a measurement, thankyouverymuch. So there's a distinct contradiction about what happened, even worse than the simultaneity breaking of relativity where observers merely disagree about when something happened.

The article then goes on to describe an extended version, but after thinking about it, I'm quite sure I don't understand it at all. No matter, this original version is complicated enough. Does it challenge something as fundamental as the nature of reality ?

Physicists generally describe reality by a set of mathematically defined conditions. For instance, causality tells us that an effect should be preceded in time by a cause. Locality says that causes propagate at the speed of light: if a photon cannot travel between the location of the cause to the location of the effect before the effect occurs, then it violates locality (and, potentially, causality). The researchers define the absoluteness of observed events, meaning that what I observe is real and does not depend on anything else. They assume that there is no super-determinism (we make free choices) and locality is still operative. The researchers refer to this trifecta as local friendliness.

Call me crazy, but "local friendliness" sounds like a bloody daft term, but that's science for you. Anyway :

They show that under the right conditions, correlations that violate these limits will be observed in the extended Wigner’s friend experiment. Their laboratory experiments confirmed that these violations do in fact occur. Local friendliness is not how the Universe operates. 

If we reject local friendliness, then we have to make some decisions. We have to accept some of the following possibilities: an observer's measurements are not necessarily real, reality is not local, super-determinism is real, or quantum mechanics ceases to function somewhere before macroscopic observers get involved.

I think I understand what's meant by reality being non-local : FTL effects meaning that things could affect other things despite no apparent connection. Super-determinism is harder due to the phrasing used : does the article mean to say this assumption means we do or not have free will ? I would presume that if there's no free will, and if everything is predetermined (including the measurements) then there's no problem, so let's go with that.

But I don't understand at all what's meant by "an observer's measurements are not necessarily real". Of course measurements can be erroneous, so I assume it's something more profound than that... but how ? If I follow the operating procedures correctly, but my equipment has an unknown fault and gives me an error, in what way is this different from the quantum version in which I get a result that contradicts someone else's ? It would appear to mean not that some things are fundamentally unreal but only that some things are fundamentally unmeasurable. But this is nothing new or unique to quantum systems; some things are fundamentally unquantifiable. You can't objectively measure mercy, or justice, or yellowness, or guilt, but clearly their mental existence doesn't invalidate the reality of what they're measuring. Measurements themselves have no physical substance so in that sense they can never be said to be "real". If there's something I'm missing here, I'd very much like to know what it is.

Likewise there's this interesting article about how long it takes the wave function to collapse :

By taking photographs to see what happens in that one-millionth of a second, scientists saw that the decision, a process referred to as wave function collapse, took some time to happen. It’s like when the police officer points her radar gun at you - your car is first going somewhere between 20 and 60 miles an hour, then between 35 and 50, then either 40, 42, or 45, then finally deciding it is going 40 miles an hour. The intriguing results show that quantum collapse is not instantaneous. It also shows us how time operates on the quantum level - and shows us that time itself may be a blurry, abstract concept. It also shows us that our concept of “now” may not really exist, and that our reality is a very weird place indeed.

Again I'm not seeing why this brings the nature of time into question. Okay, in some sense the "reality" of the electron takes some time to coalesce from wave to particle, but why would you expect it to be instant ?

I often think that a lot of this quantum jargon about wave functions and decoherence and suchlike is not much better than ancient ill-defined concepts like magic or humours... I don't think we're any closer to understanding the fundamentals of reality than they were. Sure, we've got far better cosmological models and infinitely superior understanding of gravity, material physics, chemistry, medicine, etc... but the aspect of, "what's it all about, when you get right down to it ?". Not so much.

Quantum reality is either weirdly different or it collapses

Quantum mechanics, when examined closely, poses some deep questions about reality. These questions often take the form of thought experiments, which are later (usually much later) followed up by real experiments. One of the most difficult and deepest of these is a thought experiment proposed by Eugene Wigner in the 1960s, called "Wigner's friend" (you don't want to be Wigner's friend).