@ Rav,
This is where the woo comes in. Either an act of subjective perception collapses the wavefunction, or it doesn't. You can't defer the collapse to another observer further along the chain without treating your own act of subjective perception as non-real, which is absurd.
From this one statement alone it is extremely clear you do not understand the concept of Wigner's Friend. You seriously should reconsider your stance in this debate as you clearly are not in the least bit familiar with the topic.
Yes. Many people think the idea of Wigner's Friend is absurd, but you are arguing against the idea of Wigner's Friend here, and not my own idea.
Let me dumb down the idea a bit to see if I can get you to understand.
Let's pretend your name is Eugene Wigner, and you have a friend who carries out a real "Schrodingers Cat in The Box" experiment while you are away.
Now you return to the lab and the door to the lab is closed (like a box).
OKay Now compare this situation to the Schrodinger cat in the box experiment.
Inside the lab is your friend who has already opened the box and has determined that the cat is "A - Dead" or "B - Alive".
Now Wigner knows that his friend has already "collapsed" (possibly) the wavefunction of the cat into actuality ( If you subscribe to that Interpretation of Quantum Mechanics).
So now he compares the experiment with the door in front of him. Perhaps his friend who opened the box is himself still a wavefunction in need of a collapse.
You can argue this is absurd, but this is the idea of Wigner's Friend (albeit dumbed down a bit). The idea suggests that none of us are really collapsed, although If and when we are collapsed (by the end consciousness in the chain) we would not realize we were ever in juxtaposition.
So now he opens the door and collapses his friend who thinks he collapsed the cat.
This can be expanded further.
Now Wigners wife drives to the lab and collapses Wigner who believes he has collapsed his friend and the cat, and collapses Wigner.
This can be expanded to every person they meet. An entire city can exist as a wavefunction based on the idea of Wigner's Friend (if it were true).
Now I will paste your quote below here again so you can see why it demonstrates you are not familiar with the subject of "Wigner's Friend"
This is where the woo comes in. Either an act of subjective perception collapses the wavefunction, or it doesn't. You can't defer the collapse to another observer further along the chain without treating your own act of subjective perception as non-real, which is absurd.
Let's break it down ...
This is where the woo comes in.
Ouch. Tough words from someone who does not understand the subject in the least ("Wigner's Friend").
Either an act of subjective perception collapses the wavefunction, or it doesn't.
Yet Wigner felt he might be collapsing his friend and the cat who were (according to idea of Wigner's Friend) living in superposition behind the laboratory door (The lab can be compared to a larger Schrodinger Box).
You are allowed your opinion, but it is the Wigner's Friend concept you are arguing against here, and not anything I have proposed.
You can't defer the collapse to another observer further along the chain
This is
THE ENTIRE POINT of Wigner's Friend, despite your ignorance of the subject. The concept of Wigner's Friend is exactly deferring collapse further along the chain. You nailed it exactly if you were on opposite world and you meant the exact opposite of what you said.
The Wigner's friend thought experiment posits a friend of Wigner who performs the Schrödinger's cat experiment after Wigner leaves the laboratory. Only when he returns does Wigner learn the result of the experiment from his friend, that is, whether the cat is alive or dead. The question is raised: was the state of the system a superposition of "dead cat/sad friend" and "live cat/happy friend," only determined when Wigner learned the result of the experiment, or was it determined at some previous point?
You can say the Wigner's Friend concept is hogwash, and cannot exist, but do not credit me with the concept when you should know better.
So your statement clearly shows you are not even aware of the subject material, or at least lack comprehension of it.
Earlier you said,
It's a thought experiment. No-one really knows what happens inside the box, and it certainly doesn't demonstrate that a cat can be both alive and dead simultaneously. In fact the sheer scale at which the events of our lives play out combined with the many billions of interactive observers makes any suggestion that our individual narratives could exist in some sort of superposition of possible states beyond ridiculous, especially when you extend that to past events.
which is fine because this was the way Einstein and Schrodinger thought, and the experiment does pertain to past events (if it proved to be a true concept instead of a argument against The Copenhagen Interpretation), as it deals with the gas or explosion that would have occurred previous to the door being open.
Some will argue (like Bohr, Bell, etc.) that the cat would not exist as matter while enclosed in the box, but only as a possibility wave. If you want to argue with them then do so, but it is not my concept.
The ONLY thing I have added to existing belief (by many still), is that it is expectation/belief that influences collapse as opposed to simple measuring or observing. I can also see why many would object to this, but I feel correct and this idea is in real discussion groups (not here). Belief/faith does enter the Parapsychology debate quite frequently and is the underlying principle in many religions.
http://archived.parapsych.org/sheep_goat_effect.htm
While some subscribe to the fact belief is contributing to these results, I would say that it is also the expectations of those collapsing the participants, and the expectations of those analysing the results, and the expectations of skeptics arguing against psi that all need to be factored.