I think you have just shown how the terminology can spiral out of control very, very quickly when talking about the phenomenon of consciousness.

I have no answers. I am generally some breed of physicalist when it comes to some questions of consciousness and not so much for others. It depends on the framing.

If you are asking form a physicalistic perspective then the room exists when I leave. If you are asking from a phenomenological perspective the question is far more complicated.

I think you have just shown how the terminology can spiral out of control very, very quickly when talking about the phenomenon of consciousness. — I like sushi

Thank you. That's what I'd hoped. To my eye this shows the incoherence of such talk. So mucht he worse for phenomenology.

C.G. Jung once said that the world only exists when you consciously perceive it — Jan

The actual quote was:

Without consciousness there would, practically speaking, be no world, for the world exists for us only in so far as it is consciously reflected and considered by a psyche. Consciousness is a precondition of being. — Source

It absolutely can, people can just be either unfairly dismissive or ignorant.

According to quantum mechanics, everything exists in a superposition until it is observed. 
Superposition means that different physical quantities (such as waves, forces, or electrical signals) can exist simultaneously and influence each other without losing their individual properties.
So, in my view, this means that what I do not see or am not aware of exists in a superposition—a vast range of possibilities. It only truly exists the moment I see it and become aware of it.
It seems, then, that before something is observed, everything exists—but only as possibility (superposition). 
We live in a vast field of potential outcomes that only become definite once we observe them.

And this puzzles me.... — Jan

Physicist and philosopher Karen Barad favors Niels Bohr’s explanation of the double slit experiment over Einstein or Heisenberg. Bohr does not see scientific knowledge as describing pre-existing objects with independent properties. Instead, the outcome of the double-slit experiment shows that what is observed depends on the experimental arrangement. The electron (or photon) does not have an inherent “wave” or “particle” nature independent of how we measure it. Whether we see an interference pattern (wave-like) or two distinct bands (particle-like) is a function of the measurement setup, not a revelation of some hidden essence of the electron.

Barad takes Bohr’s explanation further, claiming that reality is not made of independent objects with inherent attributes.Instead, reality consists of phenomena produced through intra-actions.The double-slit experiment demonstrates this. There is no independent electron “with” a wave-or-particle nature, only the phenomenon of electron plus apparatus. For Barad, the very concepts of “wave” and “particle” are not properties of nature-in-itself, but arise only within specific experimental arrangements. The experiment demonstrates the inseparability of observer, apparatus, and observed.

You could be right

C.G. Jung once said that the world only exists when you consciously perceive it. In that theory, only what I see truly exists — Jan

Jung seems to be saying that I personally create the reality I see. But I don't consciously or intentionally create my environment, I just passively (instinctively) accept it as a given, and interpret the incoming bits of energy as information signals from a non-self Reality. So, Epistemological Idealism doesn't make sense to me. The other varieties of Idealism : Subjective ; Objective ; Absolute ; Constitutive ; and Transcendental ; appear to be grasping at straws.

Only the Transcendental makes some Ontological sense --- in view of the Big Bang theory --- but then we have the problem of postulating an imaginary out-of-this-world Source of the incoming Information (Ideas) we interpret as Real. I don't flatly reject the God hypothesis, even though I have no personal experience to confirm it. Therefore, as an amateur philosopher, while I entertain the hypothetical notion of Idealism, for practical purposes I assume that there is a real material world out there, which is not a creation of my feeble imagination. :smile:

Perhaps we ought to distinguish between meaning or signification with existence and then the puzzle is weakened.

Unless one wants to throw away all the evidence we have of non-conscious activity prior to our existence, which helps explain (in part) why we are here at all.

“So, did the clock on your wall keep moving while you slept, or was there a leap from when you closed your eyes to when you opened them again, no time passing - nothing exists, just things leaping ahead as if time had passed?“

That’s interesting
I am busy creating a kind of an imaginary model. I hope I can fit this in
I hope to show it some day.

It's a problem for solipsism generally. And Idealism has a great deal of difficulty avoiding solipsism. If to be is to be perceived then things cease to exist when unperceived; including, it seems, other people.

Hence solipsism.

So, did the clock on your wall keep moving while you slept, or was there a leap from when you closed your eyes to when you opened them again, no time passing - nothing exists, just things leaping ahead as if time had passed? — Banno

To examine the measurements involved in clock time, (Henri) Bergson considers an oscillating pendulum, moving back and forth. At each moment, the pendulum occupies a different position in space, like the points on a line or the moving hands on a clockface. In the case of a clock, the current state – the current time – is what we call ‘now’. Each successive ‘now’ of the clock contains nothing of the past because each moment, each unit, is separate and distinct. But this is not how we experience time. Instead, we hold these separate moments together in our memory. We unify them. A physical clock measures a succession of moments, but only experiencing duration allows us to recognise these seemingly separate moments as a succession. Clocks don’t measure time; we do. This is why Bergson believed that clock time presupposes lived time.

Bergson appreciated that we need the exactitude of clock time for natural science. For example, to measure the path that an object in motion follows in space over a specific time interval, we need to be able measure time precisely. What he objected to was the surreptitious substitution of clock time for duration in our metaphysics of time. His crucial point in Time and Free Will was that measurement presupposes duration, but duration ultimately eludes measurement. — Clock time contra lived time

Idealism has a great deal of difficulty avoiding solipsism. — Banno

At least your version of it does.

You've always seem to me to avoid it only by an appeal to mysticism or changing the subject.

Even accepting Bergson's distinction between time and duration - and I don't see that we need do so - the problem remains that things cease to exist when we are "unconscious". That problem is not resolved.

C.G. Jung once said that the world only exists when you consciously perceive it. In that theory, only what I see truly exists. What I do not see, or what I am not aware of, therefore does not exist. — Jan

Substitute "the world" with "your world."

Actual quote from Jung is:

“Without consciousness there would, practically speaking, be no world, for the world exists for us only in so far as it is consciously reflected by a psyche. Consciousness is a precondition of being.”

Schrödinger had ideas along similar lines. — Jan

I can't agree with this assessment.

Jung was a psychologist, not a physicist. He meant only that our world, what we know, live, and breathe, what it is to be, is rooted in our consciousness.

This is not a statement about reality generally. It is a statement about what constitutes our personal reality. The "practically speaking" qualification makes it all the more difficult to suggest he was making any claim about the world generally.

This topic is very interesting from a sociological perspective because multiverse theories have become very popular as a solution to the Fine Tuning Problem, and yet "Consciousness Causes Collapse" (the von Neumann–Wigner interpretation) solves the problem just as well.

Why do we exist in a universe fine tuned for conscious life? Because only such life collapses potentiality into actuality. All possibilities exist, but only those with life become actual. Problem solved. If the degree of collapse corresponds to the degree of consciousness, perhaps there is even something like an iron law leading towards de Chardin's Omega Point. Makes as much sense as the multiverse.

At least, prima facie, I am not sure why "everything possible actually happens, it is just impossible to ever observe that this is so," is considered more plausible than this. I can see why some might find both absurd, but the preference for one over the other seems hard to explain as anything other than an aesthetic preference.

“Without consciousness there would, practically speaking, be no world, for the world exists for us only in so far as it is consciously reflected by a psyche. Consciousness is a precondition of being.” — Hanover

So: "If a tree falls in the woods...", basically.

Matter exists. Planets exist. If you have an atypical definition of "the world", I suppose we can just go about redefining any word vague enough if we so please. What of it?

He meant only that our world, what we know, live, and breathe, what it is to be, is rooted in our consciousness. — Hanover

I think "our idea of the world" would be best suited in place of "our world". The world existed before this hypothetical observer was even born, and would have existed if that never happened, and continues still to exist long after we're gone. I can have an idea about anything that exists, doesn't exist, or may come to exist. It should go without saying "my opinion" or "what I think to be a fact because it seems like it" are very different concepts that do not necessarily have anything to do with the physical matter and constitutional makeup of the universe, let alone how other people may view such.

I just don't see the basic elementary idea of "one's opinion" or "worldview" coming anywhere near traversing such depths of the metaphysical or anything remotely profound. Sure, most people fail to realize that. But as far as academia is concerned, this is, or at least I would hope should be, common knowledge.

So: "If a tree falls in the woods...", basically — Outlander

No. That suggests Jung was some sort of Berkelian idealist. He was not making any metaphysical claim at all. He was only indicating our psyche is mediated by our perceptions and so our consciousness of reality defines who we are.

The world existed before this hypothetical observer was even born, and would have existed if that never happened, and continues still to exist long after we're gone. I can have an idea about anything that exists, — Outlander

He's not suggesting otherwise. To the extent the external world is mediated and not directly knowable, that would evoke Kantian references of the noumenal, but not suggestions of reality blipping in and out of existence as we blink.

Again, in the Nature survey, the data is as follows:

Does a measurement require an observer?
Yes, and they must be conscious: 9%
Yes, but consciousness is not relevant (and an 'observer' can include
interaction with a macroscopic environment): 56%
No: 28%
Not sure: 8%

The supposition that there is a consensus amongst physicists that consciousness is an inherent feature of the physical universe is a fabrication. 84% of physicists reject the idea that consciousness is necessary for measurement.