If there be any misconception here, not that I think there is, it is that there is ever any instance where quantum mechanics is not in full effect.
So it is compatible with conscious observers to the extent that you imagine yourself a conscious observer, but it also works fine in situations where there is no such observer, e.g., the very early universe. There need not even be a “classical” system to interact with it.
All interpretations of quantum mechanics are exactly equivalent, and mathematically proven to be so. Some of them make no reference whatsoever to anything that could be interpreted as relating to “consciousness”. And yet, they make exactly the same predictions as the Copenhagen interpretation. Thus, if one understands anything in the Copenhagen interpretation to be dependent upon consciousness, then that understanding must be incorrect.
And there’s no consensus among physicists about which interpretation is “best”, because the consensus among physicists is that the question of which is “best” is nonsensical to begin with. Because they all make exactly the same predictions.
Only some interpretations of quantum mechanics are equivalent. An example of one that isn’t is The Gremlin Interpretation.
https://boards.straightdope.com/sdmb/showthread.php?t=644232&highlight=quantum
A boundary can be illuminated by the following thought experiment:
A large object like an asteroid can be tracked through space with radar or optical frequencies; light does not deflect it’s trajectory in a meaningful way.
But the smaller the object, the smaller the wavelength of radiation needed to resolve the imaging process…and smaller wavelengths have higher energies.
At a certain microscopic level, the object observed has such small mass and the imaging wavelength has so much punch that the object is in fact deflected…resulting in position and momentum having mutual uncertainty.
But, as stated, don’t rely on the narrative or intuition: the mathematics are there to resolve the system more accurately.
There’s lots of stuff in that book that ought to be approached with some caution, though. While it does an OK job with most topics, the narrative is often rather one-sided, and it drops the ball on a few important topics—notably, the EPR thought experiment and the issue of nonlocality in quantum mechanics.
For my money, a better, albeit somewhat more technical recent book on the various interpretations of quantum mechanics is Quantum Ontology by Peter J. Lewis. Although he’s a bit too quick to dismiss the Copenhagen interpretation, in my opinion. For an older, but eminently readable account, there’s always David Albert’s Quantum Mechanics and Experience.
There are, despite great efforts, still some physicists who hold that opinion, but it’s certainly far from a consensus, as evidenced by the copious numbers of papers, books, and talks by physicists arguing that their particular interpretation is the best one.
I’m not familiar with the Gremlin Interpretation, but if it makes different predictions than the others, then whatever it’s an interpretation of, it’s not an interpretation of quantum mechanics.
It seems that you don’t understand what is meant by interpretations of quantum mechanics. This is shown by the fact fact that you talk about interpretations making predictions. They don’t make predictions. If they did, there wouldn’t be any controversy.
I speak as someone who did postgraduate theoretical physics, including a huge amount of quantum mechanics. It was many years ago, certainly, and I’ve forgotten a lot of the details of the mathematics, but I do know something about the subject.
You are confusing the mathematical formalism of quantum mechanics (which makes predictions) with semantic understanding of the meaning of the mathematics. I suggest you at least read through the wikipedia article and understand what we are talking about.
I think what’s at issue is the difference between a theory’s predictive and explanatory power. All flavours of quantum theory will (I presume) have exquisite predictive power. But some may offer additional unique perspectives or ‘explanations’ that could help guide research directions, or simply be interesting in themselves. ETA: e.g. the many worlds interpretation
Actually I keep hearing that it’s NOT merely a matter of any possible measuring device being too blunt to not alter what’s it’s measuring; that there really is an inherent uncertainty in pairs of certain values such as position/momentum.
Of course quantum mechanics works at the cat level. It’s the only explanation for why cats are so weird.
There is only ONE quantum theory. There is only one mathematical formulation of it. It makes extremely accurate predictions, and everyone is agreed about the theory itself. There is no dispute about it. If you use the right equations to describe a specific physical system and plug in the right numbers, you will get an answer that exactly matches experiment.
But the mathematics predicts some weird results, and we find the same weird results by experiment. (In fact the weird results from experiments gave rise to the theory, which then predicted further weird results, which turned out to be verified by experiment.)
The question is what does that mathematics mean in the ‘real world’? How can we understand the nature of reality? Reality seems to be weird at some fundamental level, but how do we understand this weirdness and what implications does it have?
Some physicists don’t even want to think about it. “Shut up and calculate.” You do the calculations and you get the right results, so just put your fingers in your ears and forget about what it ‘means’.
But there are very different opinions about what it means. What exactly is the ‘wave function’? Is it the probability of getting a certain result? Is it a something physical? Does it imply non-locality? Does it imply many universes? Does it imply that consciousness is a factor? What causes the wave function to collapse? Does it in fact collapse? Is this a physical collapse, or just a mathematical convenience? Etc.
There a useful comparison on the wiki of the major interpretations. Some are deterministic, some are random. Some regard the wave function as a physical reality, some don’t. Some have collapse of the wave function, some don’t. Some mean that the observer has a role, some don’t. Some have a wave function for the whole universe, some don’t.
There is no experimental evidence to say which interpretation is correct. They are different ways of understanding the exact same mathematical theory. The question is how that mathematics corresponds with “physical reality”, and what do we mean by “physical reality”?
Is this true? Or is it that there exists no way to take a measurement with a fundamental particle, that doesn’t interact with it?
Here’s one explanation of the Heisenberg Uncertainty Principle. It’s not the same thing as the measurement affecting what you measure. I can’t explain this stuff but the various explanations boil down to this, random things will happen when particles interact.
As a very minor dilletante who suffered long with popular misconceptions about QM from reading pop-science books and watching 10-minute YouTube videos, I want to clear up one thing which I only found 10 answers deep in a closed (of course) Stack Exchange question: There’s a misconception that there is something special about conciousness or the act of measurement in collapsing a wave function. It isn’t “measurement” per se that collapses the wave function, it’s interaction with ANY particle (at least the basic ones - someone fill me in if it’s universal). There is nothing special about the particles in the cell of a retina, a particle detector, or anything else. A dog’s turd does as much to create our physical universe as we do. Now I’ll just sit back and wait for someone to quote my post and begin their reply with “Actually,…”
Thanks, TriPolar. I couldn’t remember if such a thing was an intrinsic aspect to nature, or that there’s simply no way to measure something so fundamental without poking it and collapsing its function.
Or is that a difference without a distinction?
Actually…
… if it was as simple as all that, some of the most brilliant minds in the world wouldn’t have spent decades over the question… only for it not to be resolved yet…
Only some interpretations of QM involve wave function collapse in the first place. Only some interpretations have a role for the observer. See the columns ‘Collapsing wave functions?’ and ‘Observer role?’ here.
Also see
You’re asking the wrong person about this.
If I have it right, there is a difference between the Observer Effectand the Uncertainty Principle.
Hopefully someone who knows what they are talking about will clarify all this.
I wasn’t sure whether wave function collapse was the best term to use but my main point is correct, no?
I don’t see how or why consciousnesses would have anything to do with QM. What defines consciousnesses? It seems silly to say ‘The observer has to be conscious to collapse the wave function. What is consciousnesses? I don’t know.’ So the thought experiment for this I came up with is: Say we get a machine that can run the double slit experiment all by itself. It does this in a completely sealed box except for one light it can turn on on the outside. When it sees an interference pattern it turns on an light outside the box. Will it ever turn on the light? For it to see the interference pattern the wave function must collapse each photon to a single location. But if no ‘conscious’(IE humans/dogs/cats/bugs) can observe it and the wave function only collapses on conscious observers then it will never turn on the light as the wave functions will never collapse.
Given this experiment hasn’t been done(to my knowledge) there is probably some problem with it. But I’d be curious to know why or why not this could prove a conscious observer is required.