The Heisenberg Uncertainty Principle (HUP)

Originally posted by DoctorScribbles
Similarly for quantum phenomena, you actually need to observe them if you want to make an definite statement about an exact property of them.

This I understand without difficulty.

However let's say I roll a die and a number comes up, but I don't see
it. A blind person picks up the die and hands it to me, careless of
the way in which he handled the die (i.e., unsure of which face was
up when he grabbed it).

That die roll existed. It had a value. We may not have known it and
we may never know it, but it was there. There was a discrete value,
however, the knowledge of what that value was doesn't exist.

However, according to my limited understanding of the HUP, the
particle in question actually has no values for position and velocity
until you try to measure them, in which case you get a range of
probabilities.

Or do I understand things incorrectly?

In humility,
Nemesio

Originally posted by nemesio
This I understand without difficulty.

However let's say I roll a die and a number comes up, but I don't see
it. A blind person picks up the die and hands it to me, careless of
the way in which he handled the die (i.e., unsure of whi ...[text shortened]...

Or do I understand things incorrectly?

In humility,
Nemesio

Yes, the die analogy is not perfect in the very sense that you point out.

Or, I could refine it and say that the die's roll never completed, for to roll a die means to cast it and observe its value. If I attempt to hang on to this analogy, I would say that the die was "still rolling" even after it stopped and the blind man picked it up. Still rolling, because you never observed it - a criterion for having rolled it.

I can do this semantic dance because you recall that I claimed my analogy was a conceptual one, not a physical one. Thus, I redefine the concept of "to roll."

I suppose the blind man's interference would be analogous to the power going out in the laboratory during the course of the observation experiment.

Originally posted by nemesio
This I understand without difficulty.

However let's say I roll a die and a number comes up, but I don't see
it. A blind person picks up the die and hands it to me, careless of
the way in which he handled the die (i.e., unsure of which face was
up when he grabbed it).

That die roll existed. It had a value. We may not have known it and
we may ne ...[text shortened]... t a range of
probabilities.

Or do I understand things incorrectly?

In humility,
Nemesio

Not quite. Prior to measurement, the wave equation that constitutes an exhaustive description of the evolution of the quantum system will specify a range of possible positions (momenta), each probabilistically indexed(e.g., .5 probability in this area, .5 probability in that area, where the area mentioned are decomposible into their constituent areas with corresponding changes to their respective probabilities of being the outcome of measurement). The quantum system in questiion has definite values for position and momentum, but these come in ranges idexed to probabilies. When the system is measured by a classical system, the superposition of states (or psi-function, or whatever) collapses, yielding a definite eigenvalue (one of the values that previously existed as a possible outcome of measurement). When measurement occurs, we get a definite, classical property that doesn't do anything funky to our metaphysically realist intuitions.

Originally posted by DoctorScribbles
Yes, the die analogy is not perfect in the very sense that you point out.

Or, I could refine it and say that the die's roll never completed, for to roll a die means to cast it and observe its value. If I attempt to hang on to t ...[text shortened]... not a physical one. Thus, I redefine the concept of "to roll."

Indeed. Suppose that the die was hooked up to a quantum system such that the outcome of the die roll was, in part, determined by the location that a photon struck a photoelectric plate. If so, then the avowedly classical system of the rolling die together with its quantum system causal precursor form one large system that all gets described by S's wave equation, and the result of the die roll will, hence, be a probabilistically indexed range of options. Further, suppose a man goes and picks up the die and looks at it, but you can't see the result. If so, the set of quantum system/classical die roll/man looking at die/ still gets described by S's wave equation. This, of course, is pretty much analogous the the S's cat objection to QM (raised first by Einstein, I think, though the example didn't use a cat but an explosion of dynamite). Now, suppose you go and look at the die, and suppose that you are being observed by a camera sending a signal back to my computer screen. When you look at the die, the wave function collapses, right? Well, yes and no... Even after you look at the die, if I'm observing you through the camera and my view of the die is occluded, then, from my perspective the whole system, including you, is still described by S's wave equation.

Originally posted by bbarr
Indeed. Suppose that the die was hooked up to a quantum system such that the outcome of the die roll was, in part, determined by the location that a photon struck a photoelectric plate. If so, then the avowedly classical system of the rolling die together with its quantum system causal precursor form one large system that all gets described by S's wave equat ...[text shortened]... my perspective[/i] the whole system, including you, is still described by S's wave equation.

In other words, it remains a wave function to any given observer until that observer is satisfied that he has observed it. The observer always gets the last say on whether the observation has taken place, regardless of any intermediaries who claim to have observed it.

And the whole idea of taking an observation is mostly moot anyway, because what is interesting about the system under study is the particular S, not particular realizations of S. In the same way that the interesting aspect of dice is not particular rolls, but the fact that they produce equally likely values with probabilities of 1/6.

Originally posted by bbarr
...

So wait a second.

From the die-observer's point of view, the wave collapsed,
but from the camera-observer's point of view, it didn't?

I don't see how something can have a value and not have
a value at the same time.

This reminds me of a philosophy 'joke' I heard once:

Three umpires were discussing their philosophies of making
'calls' during the game.

The first said: I call them as I see them.

The second said: Well, I call them as they are.

The third said: Well, until I call them, they aren't.

--

I get the joke, but I don't 'get it.'

Nemesio

Originally posted by DoctorScribbles
In other words, it remains a wave function to any given observer until that observer is satisfied that he has observed it. The observer always gets the last say on whether the observation has taken place, regardless of any intermed ...[text shortened]... that they produce equally likely values with probabilities of 1/6.

I don't think that captures the strangness, because S's wave equation is supposed to be a complete, exhaustive description of the system in question. What we are forced to do is to give up the notion that systems are individuated by their intrinsic properties. They are, in fact, also individuated by their relation to measuring systems. Hence when you collapse the wave function by looking at the die that is occluded from my view, there is no problem because (Q.S + Die + You qua measurer) is a metaphysically distinct system from the system (Q.S + Die + You _+ Me qua measurer).

"But surely", Nemesio's realist intutions cry out, "either the die shows a 1 or it does not. The result can't be indeterminate for anybody after Scribbles looks at it!"

Originally posted by bbarr
"But surely", Nemesio's realist intutions cry out, "either the die shows a 1 or it does not. The result can't be indeterminate for anybody after Scribbles looks at it!"

ACK! Get out of my head.

😞

Originally posted by bbarr
I don't think that captures the strangness, because S's wave equation is supposed to be a complete, exhaustive description of the system in question. What we are forced to do is to give up the notion that systems are individuated by their intrinsic properties. They are, in fact, also individuated by their relation to measuring systems. Hence when you coll ...[text shortened]... or it does not. The result can't be indeterminate for anybody after Scribbles looks at it!"

Good point. I don't think it has been previously pointed out here that observers are inherently part of the observed quantum system.

Originally posted by DoctorScribbles
Good point. I don't think it has been previously pointed out here that observers are inherently part of the observed quantum system.

That is, there is no such thing as a neutral observer?

Originally posted by nemesio
That is, there is no such thing as a neutral observer?

Nope, there is no archimedean point. No truly objective standpoint. No absolute reference frame. Reality is all smoke and mirrors, Nemesio. Get with the program!

Originally posted by bbarr
No absolute reference frame. Reality is all smoke and mirrors, Nemesio. Get with the program!

Yeah, come on Nemesio! Even Einstein knew this!

Originally posted by DoctorScribbles
Yeah, come on Nemesio! Even Einstein knew this!

Are we talking about the various experiments about balls on
trains and mirrors reflecting light in spaceships?

I can understand those.

However the scenario presented -- a die being rolled, person A
sees it and person B doesn't therefore it was both rolled and
not rolled -- blows my mind.

'The answer exists! The answer exists!' my mind screams. Just
because B doesn't observe it doesn't mean it didn't have a value.

How does his wave not collapse without his knowing it?

Nemesio

Originally posted by nemesio

However the scenario presented -- a die being rolled, person A
sees it and person B doesn't therefore it was both rolled and
not rolled -- blows my mind.

'The answer exists! The answer exists!' my mind screams. Just
because ...[text shortened]...
How does his wave not collapse without his knowing it?

Nemesio

There is not just one wave function in play. There are two, one for each system comprised of an observer and that which is being observed. B is only an observer of the system in which B is an observer. Same for A. When A observes his system, this does not mean that B's system has been observed; B is observing an entirely different system that includes him as the observer.

Originally posted by nemesio
However the scenario presented -- a die being rolled, person A
sees it and person B doesn't therefore it was both rolled and
not rolled -- blows my mind.

When you use the term 'it' in the above text, are you referring to the die that is partly constitutive of the system (Q.S. + Die + Scribbles qua measurer), or the metaphysically distinct die that is partly constitutive of the system (Q.S. + Die + Scribbles + Bbarr qua observer)? You seem to be equivocating between these two metaphysically distinct items.