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Tags Hugh Everett , quantum mechanics

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Old 29th December 2020, 04:52 PM   #121
JayUtah
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Originally Posted by Mike Helland View Post
I guess in the context of my last thread, where I was actually questioning established mainstream physics, this one wasn't supposed to be as confrontational.

Basically pointing out Everett's awesome idea in 1957 makes for an interesting software problem.
Your thread title might have been a tad misleading then.

But things got off on the wrong foot almost immediately because you said

Originally Posted by Mike Helland View Post
Ok... this dude is literally .... in 1957... saying stuff about modeling a neural network inside a particle simulation.
I don't think he was literally saying any such thing. And from what I observe about how theoretical physicists work, it would be a considerable stretch -- bordering on absurd -- to think he was. Yes, he alludes to existing types of computer storage (among other things) as illustrations of what capabilities observer would require in his interpretation, but you're taking all of that waaaaaaay too literally.

Nobody knew what Everett was talking about precisely because he was so foggy on the details, leaving physicists with no basis for evaluating his claims. It wasn't until deWitt tried to encourage formalizations of the theory that we even had anything to discuss, let alone attempt to fit math to. It wasn't because Everett was proposing esoteric problems in computability that no one had yet encountered. Computability isn't a factor in this flavor of theoretical physics.

Now if you want to revise your approach and say that an Everettian observer, if implemented on a computer, would pose interesting challenges in hardware and software, then I'm not even going to argue slightly with that. But I'm entirely certain that's not at all what Everett was thinking about. So you explore it and you publish the paper. It's your idea, so run with it.
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Old 29th December 2020, 05:11 PM   #122
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Originally Posted by JayUtah View Post
Nobody knew what Everett was talking about precisely because he was so foggy on the details, leaving physicists with no basis for evaluating his claims.

...

Now if you want to revise your approach and say that an Everettian observer, if implemented on a computer, would pose interesting challenges in hardware and software, then I'm not even going to argue slightly with that.
How about this:

An Everettian observer, implemented on a computer, would give us the "relative" state of the computer program, how it appears from the inside.
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Old 29th December 2020, 05:39 PM   #123
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Originally Posted by Thermal View Post
See, this is what turns off a lot of laypersons. Laypeople?. It makes this stunningly fascinating science sound like hippy-dippy navel-gazing.
You're turned off by the fact that the paper that first established the many worlds interpretation of QM talks about many worlds?
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Old 29th December 2020, 06:06 PM   #124
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Originally Posted by Mike Helland View Post
An Everettian observer, implemented on a computer, would give us the "relative" state of the computer program, how it appears from the inside.
I'm not sure what you mean by the "relative" state of the program. Relative to what?
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Old 29th December 2020, 06:37 PM   #125
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Originally Posted by JayUtah View Post
I'm not sure what you mean by the "relative" state of the program. Relative to what?
Relative to the internal observer.

From Everett:

Quote:
We have the task of making deductions about the appearance of phenomena
to observers which are considered as purely physical systems and are treated
within the theory. ...

It will suffice for our purposes to consider the observers to possess memo-
ries (i.e., parts of a relatively permanent nature whose states are in correspon-
dence with past experience of the observers). In order to make deductions
about the past experience of an observer it is sufficient to deduce the present
contents of the memory as it appears within the mathematical model.
In other words, as the programmers of the model, when see it for what it plainly is.

But internal observers of the model, with no special access to the RAM which defines their world, will see only what they can gleam from their interactions with their environment.

The absolute state would be the RAM of the programmer's computer. The relative state would be the measurement records of the observer.
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Old 30th December 2020, 12:17 AM   #126
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Originally Posted by Roboramma View Post
You're turned off by the fact that the paper that first established the many worlds interpretation of QM talks about many worlds?
No, I'm turned off by the fact that the universe repeatedly splitting into different branches over mundane events seems like a grade-school creative writing class solution to dealing with the collapse of the wave function. To a layperson (because I am sure that an actual understanding of QM would clear it up), it seems like a God of the Gaps way of explaining what happens to Edwin's Cat. I have a strong feeling that it does not mean what it seems to mean to a layperson, which is that it is the laziest resolution imaginable, which is what I was alluding to upthread: this stuff should not be what every article leads with. There should be a lot of contextual foundation before hitting us with this.

I read something from Hawking (can't remember where), where he is quoted as saying that it doesn't bother him that this jazz doesn;t jibe with reality, so long as it works. I'm pretty sure that s the kind of thing that laypeople should be made aware of first and foremost.

But this is not the time and place for this particular rambling. I'm waiting for my Christmas gift that I am assured will provide understanding.
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Old 30th December 2020, 03:06 AM   #127
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Originally Posted by Thermal View Post
No, I'm turned off by the fact that the universe repeatedly splitting into different branches over mundane events seems like a grade-school creative writing class solution to dealing with the collapse of the wave function. To a layperson (because I am sure that an actual understanding of QM would clear it up), it seems like a God of the Gaps way of explaining what happens to Edwin's Cat. I have a strong feeling that it does not mean what it seems to mean to a layperson, which is that it is the laziest resolution imaginable, which is what I was alluding to upthread: this stuff should not be what every article leads with. There should be a lot of contextual foundation before hitting us with this.

I read something from Hawking (can't remember where), where he is quoted as saying that it doesn't bother him that this jazz doesn;t jibe with reality, so long as it works. I'm pretty sure that s the kind of thing that laypeople should be made aware of first and foremost.

But this is not the time and place for this particular rambling. I'm waiting for my Christmas gift that I am assured will provide understanding.
Step 1.

The things around you are real, and what you think is real, is real.

Good so far?
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Old 30th December 2020, 05:02 AM   #128
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Originally Posted by Thermal View Post
dealing with the collapse of the wave function.
That's the problem.

This thread is about Everett.

Everett treats the collapse of the wave function as something that has never been observed and is not real.

https://plato.stanford.edu/entries/qm-everett/

Quote:
Everett’s solution to the problem was to drop the collapse postulate from the standard formulation of quantum mechanics then deduce the empirical predictions of the standard collapse theory as the subjective experiences of observers who were themselves modeled as physical systems in the theory.

Last edited by Mike Helland; 30th December 2020 at 05:18 AM. Reason: added quote
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Old 30th December 2020, 05:34 AM   #129
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Originally Posted by Mike Helland View Post
That's what the Many Worlds Interpretation, the so called Everett interpretation.

It could be right. There could be parallel universes.

I sort of have my doubts. And even if there were, I kinda have my doubts they need to be invoked to explain our universe.

But it's ok to talk about things without committing to 100% belief in them.

Personally, I think the most interesting part of Everett's relative state formulation applies even if the underlying model isn't wave mechanics, in which case, wouldn't lead to parallel worlds.
You were saying earlier that one can have memories which are the product of parallel universes.

Therefore, if you can show objective evidence of these parallel universes, then show this objective evidence of parallel universes.

If you can actually do such a thing, then I (and many others here on the Forum) will take your ideas more seriously.
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Old 30th December 2020, 05:46 AM   #130
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Originally Posted by Crossbow View Post
You were saying earlier that one can have memories which are the product of parallel universes.
According to the Many Worlds Interpretation, sure.

That's not what I personally believe in though.

Last edited by Mike Helland; 30th December 2020 at 05:48 AM.
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Old 30th December 2020, 07:51 AM   #131
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Originally Posted by Crossbow View Post
You were saying earlier that one can have memories which are the product of parallel universes.

Therefore, if you can show objective evidence of these parallel universes, then show this objective evidence of parallel universes.

If you can actually do such a thing, then I (and many others here on the Forum) will take your ideas more seriously.
You can have memories of earlier times, before a branching occurs, that will be shared, after the branching, with other branches (because they branched after those memories formed).

Unless I'm misunderstanding what's being said here, you can't have memories that are the product of some parallel universe after it's branch diverged from yours. The branches simply don't interact anymore.

If Mike is claiming otherwise he's misunderstanding Many Worlds.
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Old 30th December 2020, 07:54 AM   #132
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Or he's misunderstanding "product of".
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Old 30th December 2020, 08:14 AM   #133
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Originally Posted by Mike Helland View Post
According to the Many Worlds Interpretation, sure.

That's not what I personally believe in though.
If you can ever manage to figure out what you are saying, then make sure to let the rest of know.

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Old 30th December 2020, 10:28 AM   #134
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Originally Posted by Mike Helland View Post
Relative to the internal observer.
What would an "internal observer" be in the context of a running software process? You seem to be trying to imbue a computer program with a consciousness that's not strictly a product of running code on a processor.

Quote:
In other words, as the programmers of the model, when see it for what it plainly is.
Well, yes, in a von Neumann architecture I can examine the contents of memory and the machine registers and understand a program contained in a computer as an automaton.

Quote:
But internal observers of the model, with no special access to the RAM which defines their world, will see only what they can gleam from their interactions with their environment.
This is where it's far from clear what kind of software constructions or techniques you're talking about. If an "internal observer" is merely part of a computer program implemented with no knowledge of the rest of the program, and operating merely on a designated set of inputs generated elsewhere in the program (or by another program), and the result is a change of local state within the observer (or a record, private to the observer, of the state transition), then I don't see how this presents an interesting problem in computing.

You imply that to do so meaningfully, so as to simulate an Everettian system over a significant amount of time for a significant amount of particles, would require substantial computational resources, and on that basis I agree. But unless one is in the business of making and selling physical computers, that's not necessarily an interesting problem. In computer science, in terms of computability, the classic automaton for describing such systems -- the Turing machine -- presumes an infinite storage capacity. That makes it less an interesting problem.

Quote:
The absolute state would be the RAM of the programmer's computer. The relative state would be the measurement records of the observer.
If I understand you correctly, a change of terminology is probably in order. If the "observer" is simply a component of software interacting with other software (and/or with external inputs to the computer), then its "measurement records" would have to be stored in the same sort of memory as anything else in the program. I think what you mean to say is that the observer's storage would be visible to it, and would contain, among other things, the "measurement records" arising out of its inputs over time. But the entire memory image of the program (or entire computer) at some given instant would constitute the absolute state. I think rather than talking about specific storage mechanisms, it would be better to talk about local versus global accessibility. Or perhaps you could talk about how virtual memory is implemented in RAM subsystems as a possibly better analogy.

You started out talking about a neural net "running inside a particle system," whatever that arrangement would look like. I assume you mean a neural net whose inputs are generated by sampling a particle system in some way. One neural net might sample it in one way, and a parallel (but separate) neural net might sample it differently and therefore obtain a different outcome. It then falls to us to determine what "relative" means in the Everettian sense as far as these software constructs are concerned.

Clearly the state of one net would be indpenendent of another net, and its current state would be relative to its prior state. Net A would have a different relative final state than Net B, given the same prior state but different input samples. Interestingly, neural nets exactly express the interpretation that the observer has experienced a distinct set of events, but does not explicitly store each event. It stores only the accumulation of the effects of events. Thus Net A can have a present state that shows the accumulation of events A, B, and C, while Net B can have a different present state that reflects its experience as A, B, and D. They split at the point were one net absorbed event C and the other absorbed event D. But it's unclear how this pattern would express or give rise to something like a universal wave function.

Or perhaps you meant that each node in the net is an independent "observer" and the overall state of the net would be the continuing superposition of the quantum states. You'll have to be more clear in how you intend software concepts to mimic, or be mimicked by, elements of Everett's formulation. Right now it sounds like a lot of vague handwaving.

But in fairness, most of the criticism against Everett -- justly so -- was that his original proposal was a lot of vague handwaving. When I asked you provide the mathematical model of an Everett observer, it was with slightly nefarious intent because I knew he hadn't proposed one; I wanted you to acknowledge that. That doesn't mean that others haven't tried, and maybe you should endeavor to be more conversant with those attempts before you try to present Everett's work as "the" way to understand quantum mechanics. Your critics are right to draw your attention to the many-worlds hypothesis and other work that followed from Everett because it is only there that we encounter the actual problems and only there that we escape Everett's vaguely-worded prose. You can't ignore those who have done the heavy lifting to try to find ways to make Everett's theory work, especially if your method for investigating the effects of those formulations is going to be the relatively unforgiving toolchest of computer software.

It's still unclear what you're trying to do here. You're talking about software algorithms and data structures as components for expressing concepts in theoretical physics. But it's unclear why. You say variously that physics uses this approach to develop theories, which is not generally true, and then later that theoretical physics poses interesting problems in computation, which might be true depending on how you further define your terms.
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Old 30th December 2020, 11:51 AM   #135
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Originally Posted by Mike Helland View Post
Step 1.

The things around you are real, and what you think is real, is real.

Good so far?
No. My inner metaphysician is already cussing up a blue streak.

Originally Posted by Mike Helland View Post
That's the problem.

This thread is about Everett.

Everett treats the collapse of the wave function as something that has never been observed and is not real.

https://plato.stanford.edu/entries/qm-everett/
Yeah, thanks, I get that. To not have to deal with when the cat dies or not dies, Everett proposes that the whole of the universe branches off into a whole other universe, and this is extrapolated to mean the universe is continuously branching off into nearly/infinite versions. That, to my frequently inebriated ken, is an an unsatisfactory ad hoc God of the Gaps resolution. Where are these universes? By what mechanism do they divide? All that fun stuff.

But again, this is not the thread for this action. You guys have apparently resolved this to your satisfaction and are on another topic of discussion. So I'll bow out for now, thanks. Have to prepare for tomorrow night's debauchery anyway.
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Old 30th December 2020, 02:34 PM   #136
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Originally Posted by JayUtah View Post
What would an "internal observer" be in the context of a running software process?

...

It's still unclear what you're trying to do here.
Thanks for taking the time to try to figure this out.

I'll try to clarify the best I can. One of the things that makes this so complicated is actually how simple it is.

The model will look something like this:

Code:
var particles = [] //put initial conditions here
while (true) {
    //put laws of physics here
}
Everett stresses repeatedly that the observer must be "purely physical", so nothing beyond what we see here should be permitted. No special observer component, or function. Plain physics.

Let's say you are in a room with a piece of paper, and a clock. Every time you here a buzzer sound, you look at the clock, and write down the time on the piece of paper.

Now let's model that. How?

Directly.

You are made of particles. Your clock is made of particles. Your paper is made of particles.

The particles array in the model should contain all the particles it takes to make you, and to make your clock and pen and paper.

As the program runs in a loop on the laws of physics, inside the collection of particles, on the modeled piece of paper, will exist the measurement records of the modeled observer.

The relative state will be encoded on that virtual piece of paper.

The absolute state is the particles array as-is in RAM.

Of course, the observer could be a tiny computer like an Arduino with a web cam and computer vision software. Doesn't have to be human.

Does that get us any closer?
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Old 31st December 2020, 10:07 AM   #137
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Originally Posted by Thermal View Post
No, I'm turned off by the fact that the universe repeatedly splitting into different branches over mundane events seems like a grade-school creative writing class solution to dealing with the collapse of the wave function.
I read that Carrol is using another interpretation of the many worlds in the many-worlds interpretation, that the many worlds are really just possible worlds, only one of which is real. The “collapse” is when it becomes clear which one is the real one.
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Old 31st December 2020, 10:33 AM   #138
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Originally Posted by Thermal View Post
No, I'm turned off by the fact that the universe repeatedly splitting into different branches over mundane events seems like a grade-school creative writing class solution to dealing with the collapse of the wave function.
Take a step back. Suppose macroscopic objects can be in superposition states. Suppose you were in a superposition state: a Thermal that saw a dead cat, and a Thermal that saw a live cat. How would you know that you were in a superposition state?

Well, you wouldn't. The part of your wave function which saw a dead cat wouldn't know about the part of your wave function which saw a living cat.

The point isn't just that we're looking for a way to deal with the collapse of the wave function. The point is, we don't actually know that the wave function collapses in the first place. And if it doesn't, well, "many worlds" (or really, many superpositions) is a pretty obvious answer to what you're left with.

Quote:
I read something from Hawking (can't remember where), where he is quoted as saying that it doesn't bother him that this jazz doesn;t jibe with reality, so long as it works.
My basic attitude is that wave function collapse is basically what happens when you want to stop doing quantum mechanics. Frequently this is because it's simply impossible to do: you've interacted with a system with far too much complexity to model accurately. So what exactly happens in that process is a bit of a black box, so which interpretation is correct is kind of irrelevant as a practical matter.
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Old 31st December 2020, 11:13 AM   #139
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Originally Posted by steenkh View Post
I read that Carrol is using another interpretation of the many worlds in the many-worlds interpretation, that the many worlds are really just possible worlds, only one of which is real. The “collapse” is when it becomes clear which one is the real one.
Ok, but that's the paradox posed by the Cat, no? What is happening between the possibility and the actualization? The absurdity of kitty being a standing probability wave is so ludicrous that it begs for a more satisfactory answer. That's the broad brush of the Cat AIUI, anyway.
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Old 31st December 2020, 11:29 AM   #140
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Originally Posted by Ziggurat View Post
Take a step back. Suppose macroscopic objects can be in superposition states. Suppose you were in a superposition state: a Thermal that saw a dead cat, and a Thermal that saw a live cat. How would you know that you were in a superposition state?

Well, you wouldn't. The part of your wave function which saw a dead cat wouldn't know about the part of your wave function which saw a living cat.

The point isn't just that we're looking for a way to deal with the collapse of the wave function. The point is, we don't actually know that the wave function collapses in the first place. And if it doesn't, well, "many worlds" (or really, many superpositions) is a pretty obvious answer to what you're left with.
What it tells me is the reasoning went off the rails somewhere along the line, which is what I was alluding to about an equation producing a nonsensical result. You don't try to keep forcing further absurdities till you get an answer that makes sense. That's like the Far Side comic that has step #3 as 'then a miracle happens'.

Quote:
My basic attitude is that wave function collapse is basically what happens when you want to stop doing quantum mechanics. Frequently this is because it's simply impossible to do: you've interacted with a system with far too much complexity to model accurately. So what exactly happens in that process is a bit of a black box, so which interpretation is correct is kind of irrelevant as a practical matter.
Isn't that the major dilemma in physics, to come up with a unified theory that encompasses QM and the macro stuff in Relativity? From my light duty reading, it seems like the quantum world is running on different principles, and reconciling them is where we get thought experiments like the Cat. Isn't it reasonable to conclude that they simply work differently than the big stuff?

Again, I'm not trying to drag the discussion down to the kiddie pool. My understanding of the relevant math and physics is woefully behind any kind of meaningful comprehension level, so I feel like even voicing an objection is a bit presumptuous. But what the hell. I'll be so drunk soon that I'll be seeing superpositions everywhere.
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Old 31st December 2020, 11:54 AM   #141
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Originally Posted by Thermal View Post
Isn't that the major dilemma in physics, to come up with a unified theory that encompasses QM and the macro stuff in Relativity? From my light duty reading, it seems like the quantum world is running on different principles, and reconciling them is where we get thought experiments like the Cat. Isn't it reasonable to conclude that they simply work differently than the big stuff?
This is big part of DeWitt's letter's to and from Wheeler and Everett.

Check out the last page of each of these letters:

http://ucispace.lib.uci.edu/handle/10575/1183
http://ucispace-prod.lib.uci.edu/xml...dle/10575/1132

To this day, I think these questions are somewhat open.
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Old 31st December 2020, 01:00 PM   #142
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Originally Posted by Thermal View Post
What it tells me is the reasoning went off the rails somewhere along the line, which is what I was alluding to about an equation producing a nonsensical result.
The equation produces a wave function. The wave function gives us some of the best, most accurate experimental numbers in physics. I'm not sure how that's nonsensical.

Quote:
You don't try to keep forcing further absurdities till you get an answer that makes sense.
What's the criteria for what makes sense? That it feels right?

Sorry, you will never get that. Reality doesn't feel right, because our brains aren't adapted to understand all of reality. There is no possible escape from quantum weirdness, Bell saw to that.

Quote:
Isn't that the major dilemma in physics, to come up with a unified theory that encompasses QM and the macro stuff in Relativity? From my light duty reading, it seems like the quantum world is running on different principles, and reconciling them is where we get thought experiments like the Cat. Isn't it reasonable to conclude that they simply work differently than the big stuff?
There's a critical distinction that's getting brushed over here but it needs to be made. The major dilemma you refer to is reconciling quantum mechanics with general relativity. They are incompatible. One or the other, or both, must break down at some level under sufficiently extreme conditions. It may be that such conditions never manifest in the universe that we can ever access, but logically speaking there is still a contradiction. It is also quite possible that whatever corrections must be made don't actually matter for almost anything we do, since the conditions under which the theories don't work are so extreme. This would be directly analogous to how you don't need special relativity if velocities are low, since it reduces to Newtonian mechanics under such conditions, except we can work with systems that require special relativity but we might never work with systems that intersect both quantum mechanics and general relativity.

But the Schrodinger's Cat thought experiment has nothing to do with that. It's about the conflict between quantum mechanics and our intuitive understanding of the macroscopic world. You don't need general relativity for that. Newtonian physics works fine, and quantum mechanics actually has no problems with Newtonian physics. It contains weirdness, but no contradictions.

Quote:
But what the hell. I'll be so drunk soon that I'll be seeing superpositions everywhere.
Just don't get yourself into a superposition of drunk and sober, that'll really mess you up.
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Old 31st December 2020, 01:14 PM   #143
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Originally Posted by Thermal View Post
Ok, but that's the paradox posed by the Cat, no? What is happening between the possibility and the actualization? The absurdity of kitty being a standing probability wave is so ludicrous that it begs for a more satisfactory answer. That's the broad brush of the Cat AIUI, anyway.
I don't think it's any more ludicrous than kitty being sentient electromagnetic forcefield emitted by a cloud of infinitesimal motes.
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Old 31st December 2020, 01:37 PM   #144
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Originally Posted by Mike Helland View Post
Everett says:



A video camera can do that. An electron cannot.
Why can't an electron do that? Consider an electron that is deflected/accelerated by 4 different fields at various points. It's position, velocity and direction of travel is dependant on all 4 interactions so it carries the history of all 4 interactions along with it.
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Old 31st December 2020, 01:44 PM   #145
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Originally Posted by lomiller View Post
Why can't an electron do that? Consider an electron that is deflected/accelerated by 4 different fields at various points. It's position, velocity and direction of travel is dependant on all 4 interactions so it carries the history of all 4 interactions along with it.
Let's say I'm in a room with a tennis ball, and I swat it 4 times.

You walk into that room, the tennis ball has come to a rest and is lying on the floor.

Can you tell me where I was each of the 4 times I hit the ball, in what direction and how hard?

Can you do that for an electron?

Only given the video recording of me in the room could you do that.

Given a history of the electron, we can tell what happened to it. You don't get just that from looking at though.
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Old 31st December 2020, 02:31 PM   #146
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Originally Posted by Mike Helland View Post
Let's say I'm in a room with a tennis ball, and I swat it 4 times.

You walk into that room, the tennis ball has come to a rest and is lying on the floor.

Can you tell me where I was each of the 4 times I hit the ball, in what direction and how hard?

Can you do that for an electron?

Only given the video recording of me in the room could you do that.

Given a history of the electron, we can tell what happened to it. You don't get just that from looking at though.
The distinction you are trying to make is false. You think the electron is different because it contains less information than the video recording. And that's true, it does. But the video recording is incomplete as well. A VHS recording will have less information than a 4K digital camera recording of the same thing. But all of them will be incomplete, all of them will fail to record something about the events. None of this is predicated on the recorded information being complete, it never is because it never can be. It suffices that some information is somehow recorded. The difference between that 4K digital camera and an individual electron is a matter of degrees, not fundamental difference.
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Old 31st December 2020, 03:11 PM   #147
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Originally Posted by Ziggurat View Post
The distinction you are trying to make is false. You think the electron is different because it contains less information than the video recording. And that's true, it does. But the video recording is incomplete as well. A VHS recording will have less information than a 4K digital camera recording of the same thing. But all of them will be incomplete, all of them will fail to record something about the events. None of this is predicated on the recorded information being complete, it never is because it never can be. It suffices that some information is somehow recorded. The difference between that 4K digital camera and an individual electron is a matter of degrees, not fundamental difference.
As per Everett:

Quote:
We require only that they be capable of the interpretation "The observer has experienced the succession of events A, B,..., C."
A 4K camera and VHS can do that.

An electron and a tennis ball cannot.

Cameras and electrons are different in that respect.
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Old 31st December 2020, 03:26 PM   #148
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Originally Posted by Mike Helland View Post
As per Everett:



A 4K camera and VHS can do that.

An electron and a tennis ball cannot.

Cameras and electrons are different in that respect.
No. You are trying to interpret his words in a non-technical sense without understanding their meaning. You are using "experience" to mean what a person remembers of their experience, in which case VHS video and memory are comparable. But what the human brain remembers holds no significance in quantum mechanics. The important part is simply that information about what happened is contained within the state of the system. And whether that's a few degrees of freedom or a huge number of degrees of freedom is a different in scale, not in kind.
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Old 31st December 2020, 03:36 PM   #149
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Originally Posted by Mike Helland View Post
As per Everett:
We require only that they be capable of the interpretation "The observer has experienced the succession of events A, B,..., C."
A 4K camera and VHS can do that.

An electron and a tennis ball cannot.

Cameras and electrons are different in that respect.
If I subject the tennis ball to events A, B, and D, and then leave it in a state that could have been caused by A, B, and C, the system meets Everett's criteria.

Assuming we take Everett's plain English to be a rigorously defined and exact description of the mechanical prinicples. Which we probably shouldn't, since QM is maths and not English.
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Old 31st December 2020, 04:28 PM   #150
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Originally Posted by steenkh View Post
I read that Carrol is using another interpretation of the many worlds in the many-worlds interpretation, that the many worlds are really just possible worlds, only one of which is real. The “collapse” is when it becomes clear which one is the real one.
That's very clearly not what he says if you read or listen to his words. He says very explicitly that all those other worlds are real. The wavefunction is what exists, and when it branches that doesn't cause the other branches to cease to exist somehow.
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Old 31st December 2020, 04:36 PM   #151
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Originally Posted by Mike Helland View Post
As per Everett:
Why is it so difficult for you to comprehend the possibility that Everett's words can be parsed differently than what you've latched onto?
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Old 31st December 2020, 04:36 PM   #152
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Originally Posted by Ziggurat View Post
You are using "experience" to mean what a person remembers of their experience, in which case VHS video and memory are comparable.
Not exactly.

As Everett says:

Quote:
For such machines we are justified in using such phrases as "the machine has perceived A" or "the machine is aware of A" if the occurrence of A is represented in the memory, since the future behavior of the machine will be based upon the occurrence of A. In fact, all of the customary language of subjective experience is quite applicable to such machines, and forms the most natural and useful mode of expression when dealing with their behavior, as is well known to individuals who work with complex automata.
A tennis ball doesn't produce a series of measurement records.

It's that simple.
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Old 31st December 2020, 04:38 PM   #153
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Originally Posted by JayUtah View Post
Why is it so difficult for you to comprehend the possibility that Everett's words can be parsed differently than what you've latched onto?
That's not difficult to understand.

If you parse Everett different, provide the quotes you parse differently and your paraphrasing.

Here's from the original post:

* Everett, Hugh, (1957) "Relative State Formulation of Quantum Mechanics", Reviews of Modern Physics, 29: 454462.

page 9:

Quote:
We have the task of making deductions about the appearance of phenomena to observers which are considered as purely physical systems and are treated within the theory.

It will suffice for our purposes to consider the observers to possess memo- ries (i.e., parts of a relatively permanent nature whose states are in correspon- dence with past experience of the observers). In order to make deductions about the past experience of an observer it is sufficient to deduce the present contents of the memory as it appears within the mathematical model.

As models for observers we can, if we wish, consider automatically func- tioning machines, possessing sensory apparatus and coupled to recording devices capable of registering past sensory data and machine configurations. We can further suppose that the machine is so constructed that its present actions shall be determined not only by its present sensory data, but by the contents of its memory as well. Such a machine will then be capable of performing a sequence of observations (measurements), and furthermore of deciding upon its future experiments on the basis of past results. If we consider that current sensory data, as well as machine configuration, is im- mediately recorded in the memory, then the actions of the machine at a given instant can be regarded as a function of the memory contents only, and all relavant [sic] experience of the machine is contained in the memory.

For such machines we are justified in using such phrases as "the machine has perceived A" or "the machine is aware of A" if the occurrence of A is represented in the memory, since the future behavior of the machine will be based upon the occurrence of A. In fact, all of the customary language of subjective experience is quite applicable to such machines, and forms the most natural and useful mode of expression when dealing with their behavior, as is well known to individuals who work with complex automata.

The symbols A, B, ..., C, which we assume to be ordered time-wise, there- fore stand for memory configurations which are in correspondence with the past experience of the observer. These configurations can be regarded as punches in a paper tape, impressions on a magnetic reel, configurations of a relay switching circuit, or even configurations of brain cells. We require only that they be capable of the interpretation "The observer has experienced the succession of events A, B,..., C."

The mathematical model seeks to treat the interaction of such observer systems with other physical systems (observations), within the framework of Process 2 wave mechanics, and to deduce the resulting memory configura- tions, which are then to be interpreted as records of the past experiences of the observers.
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Old 31st December 2020, 04:58 PM   #154
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Originally Posted by Mike Helland View Post
If you parse Everett different, provide the quotes you parse differently and your paraphrasing.
I already have. You simply repeat the same quote from Everett as if it's self-explanatory that he means what you think he means. That's why, after several attempts, I've concluded that you're incapable of thinking differently.
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Old 31st December 2020, 05:19 PM   #155
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Originally Posted by Mike Helland View Post
I'll try to clarify the best I can. One of the things that makes this so complicated is actually how simple it is.
No, the problem is that you're trying to conceptualize something in simple terms that really isn't simple, or even well defined.

Quote:
The model will look something like this:

Code:
var particles = [] //put initial conditions here
while (true) {
    //put laws of physics here
}
This is literally every algorithm ever, shorn of anything that would give it meaning or express intent. This tells me nothing about the roles you envision various software abstractions to play.

Quote:
Let's say you are in a room with a piece of paper, and a clock. Every time you here a buzzer sound, you look at the clock, and write down the time on the piece of paper.

Now let's model that. How?
What exactly are you trying to model and at what level of abstraction? You've described a protocol that is essentially a sampling-and-recording exercise, but then you say

Quote:
You are made of particles. Your clock is made of particles. Your paper is made of particles.

The particles array in the model should contain all the particles it takes to make you, and to make your clock and pen and paper.
which leads me to think you're trying to model the behavior of a system at a completely different level and type of abstraction.

How would a particle be represented in your model? You mention a "particle system," which to me invokes a family of algorithms and data structures that are helpful in mimicking the visual appearance of various phenomena. But I don't see why that would, in any way, model the theoretical-physics notion of a particle such as you say your scene is composed of.

Quote:
As the program runs in a loop on the laws of physics...
Which specific laws?

Quote:
...inside the collection of particles, on the modeled piece of paper, will exist the measurement records of the modeled observer.
You're whiplashing between two different models at different levels of granularity employing different primitives. This is nonsensical. It seems like you really don't have a coherent idea, but you're just making sure you mention all the concepts you previously alluded to in order to make it seem like you're not floundering.

Quote:
The relative state will be encoded on that virtual piece of paper.

The absolute state is the particles array as-is in RAM.
How is your "virtual paper" not also simply stored in computer memory? Where does the "neural net" fit in? How will your "particle system" represent the nature of particles the way the are understood in theoretical physics through all the permutations? What parts of this model do you think constitute Everett's observer?

Quote:
Of course, the observer could be a tiny computer like an Arduino with a web cam and computer vision software. Doesn't have to be human.
No. You're entirely mired in the concrete thinking that failed students of quantum mechanics stumble over when they eschew the actual math and try to grope their way along by relying on analogies, examples, and thought experiments. You need to arrive at an understanding of the fundamental concepts, not continually reapply inapt macro-physical analogies.

Quote:
Does that get us any closer?
No, and at this point it's fairly clear you don't really have any viable ideas.
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Old 31st December 2020, 06:07 PM   #156
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Originally Posted by JayUtah View Post
This is literally every algorithm ever, shorn of anything that would give it meaning or express intent. This tells me nothing about the roles you envision various software abstractions to play.
There are no various software abstractions.

No special rules. No postulates particular to observer. That's Everett's idea. That's why he drops the collapse postulate from his formulation. It's a special rule just for observation.

Quote:
What exactly are you trying to model and at what level of abstraction?
A system of particles, in which one subsystem makes measures of another subsystem.

That's it. No level of abstraction. No special rules.


Quote:
which leads me to think you're trying to model the behavior of a system at a completely different level and type of abstraction.
Nope. Always was and is a particle simulation, from message #1.

Everett's "universal wavefunction" is a wavefunction that describes every particle in the universe.

This is a computer model version.

Quote:
How would a particle be represented in your model? You mention a "particle system," which to me invokes a family of algorithms and data structures that are helpful in mimicking the visual appearance of various phenomena.
Not at all. More like a game physics engine that can do the double slit experiment.

Everett's formulation doesn't require a specific model of a particle. Although, in the ones I've been using, particles don't have a position as much as they have a distance from whatever they're entangled with.


Quote:
Which specific laws?
Well, we know the model should have photons, cause otherwise how would the atoms stick together and observers be able to see objects?

So, quantum electrodynamics.

What's cool about this is, my main motivation, and also Everett's (dissertation's first paragraphs) is that under this scheme we could add some graviton particles and wind up with a quantum theory of gravity.

(Oddly enough Everett's goal was to make a foundation of QM receptive to gravity.)

Quote:
You're whiplashing between two different models at different levels of granularity employing different primitives. This is nonsensical.
Sorry, I think that's what is happening your mind.

In mind, it's always been var particles = [].


Quote:
How is your "virtual paper" not also simply stored in computer memory?
It is. It's the information encoded on it that we're after.

Quote:
Where does the "neural net" fit in?
The computer vision software. I've used OpenCV for projects.

Quote:
How will your "particle system" represent the nature of particles the way the are understood in theoretical physics through all the permutations?
Everett's notion seems to be the measurement records of the observer should faithfully recreate our own measurement record in real life.

Quote:
What parts of this model do you think constitute Everett's observer?
The sub-system of the particle simulation that makes measurements of other sub-systems.

Last edited by Mike Helland; 31st December 2020 at 06:09 PM. Reason: quote formating
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Old 31st December 2020, 06:23 PM   #157
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As far as levels of abstractions there are exactly two, which relate to Everett's absolute state and relative state:

There is a supercomputer running a particle simulation and a programmer that can examine its state.

The particle simulation contains a group of particles acting as microcomputer with a webcam and computer vision software. The CV software exists and operates purely by the rules of the particle simulation, like building a computer in minecraft.
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Old 31st December 2020, 07:18 PM   #158
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Originally Posted by Mike Helland View Post
There are no various software abstractions.
You've consistently alluded to at least two. You said in your original post that you thought Everett was envisioning a "neural net" operating inside a "particle system." Those are both software abstractions. Farther down the post, you talk about "subsystems" that perform "measurements" of other subsystems. Those are additional software abstractions.

Quote:
That's why he drops the collapse postulate from his formulation.
That has nothing to do with my criticism.

Quote:
A system of particles, in which one subsystem makes measures of another subsystem.
Okay, now flesh out the body of your loop to show more about what those "subsystems" look like and what "measurement" would consist of in terms of these abstractions.

Quote:
That's it. No level of abstraction.
If you're saying there's no level of abstraction, then you don't know what level of abstraction means.

Quote:
Nope. Always was and is a particle simulation, from message #1.
Your initial post mentions a "particle system," which means a specific thing in computer science.

Quote:
Everett's "universal wavefunction" is a wavefunction that describes every particle in the universe.

This is a computer model version.
Tell me how the data structures that represent the "particles" in your model would reflect correctly the mathematics of a wave function as Everett uses the term.

Quote:
Not at all. More like a game physics engine that can do the double slit experiment.
Okay, so first what you're talking about is a physics engine. A particle system is a particular technique within the general framework of game physics. Particle systems are specialized so as to mimic the visual appearance of certain kinds of time-dependent effects, but not all physical phenomena.

Ironically, the double-slit experiment happens to fall into the class of problems, a visual description of which could be generated (and, to a certain extent, its underlying physics modeled) by a classical particle system. This is not true of all object interactions, or even an appreciable fraction of them. If you're trying to model a general solution, you need more.

Quote:
Everett's formulation doesn't require a specific model of a particle.
Quantum mechanics requires a formulation for a particle. Just because Everett doesn't supply a specific model for his interpretation of it doesn't mean one is required. That's a bug in Everett's dissertation, not a feature. All the follow-on work -- the work that deals with actual math -- requires such formulations, and as such propose them. If you plan to model an Everett system at the level of abstraction that captures the behavior of particles, you require one too.

Quote:
Well, we know the model should have photons, cause otherwise how would the atoms stick together and observers be able to see objects?
This is immediately wrong. You think an Everettian observer requires photons, in essence that observation -- in the quantum mechanics sense -- is the same as literally seeing an object as you and I would. This is why you keep referring to video cameras, webcams, microcontrollers, and the like. You really have no idea what observation means in the context of quantum mechanics.

Quote:
What's cool about this is, my main motivation, and also Everett's (dissertation's first paragraphs) is that under this scheme we could add some graviton particles and wind up with a quantum theory of gravity.
Okay, you want to fly at the "gee whiz, this is so profound!" altitude. I don't want to hear about what you think is "cool." I want to know if you've actually considered this problem at a serious level. So far you've given us an array and a while-loop. Rhapsodizing over what this vague theory could possibly do is exactly the kind of navel-gazing you bristled at when someone else accused you of engaging in it.

Quote:
Sorry, I think that's what is happening your mind.
So why do you ignore or gloss over the parts of my discussion that illustrate where you change scope? I assure you have decades of experience in professional scientific requirements analysis at all levels up to and including NASA and the U.S. Department of Energy. I may still be misunderstanding what you intend, but I assure you the flaws I see in your approach are not simply all in my head.

Quote:
It is. It's the information encoded on it that we're after.
No. If your data structure is simply a set of vaguely-described "particles," then the whole notion of "encoding" information on an object that exists at a higher-level of abstraction is ill-formed. And as we discover below, it derives from your complete and utter misunderstanding of what observation means in any context of quantum mechanics.

Quote:
The computer vision software. I've used OpenCV for projects.
So the neural net is the literal eyeball in your model? Your notion of a "neural net" is that it's computer vision software? Yes, neural networks are one way of solving the problem of object recognition in computer vision, but by no means the only way. Conversely, neural networks are a class of solutions for all sorts of problems in expert systems, most of which have nothing to with vision or photons.

So you say "particle system" when you mean "physics engine," and you say "neural net" when you mean computer vision. Not only are you unfamiliar with the basic ideas in quantum mechanics, you seem to be unfamiliar with fundamental concepts and techniques in computer science. I'm sure you have achieved a degree of satisfaction and success in integrating canned components in order to solve various problems. But what you're trying to do here requires computer science, not just coding ability.

Quote:
Everett's notion seems to be the measurement records of the observer should faithfully recreate our own measurement record in real life.
No. You're still thinking way too literally. As in, comical levels of literalness.

Quote:
The sub-system of the particle simulation that makes measurements of other sub-systems.
So already you need more than just a simple array of individual particles. Clearly these particles must be treated differently depending on what "subsystem" is acting upon them, in some way you have yet to define. So you need to flesh out your pseudocode to express the relationship between "subsystems" and "particles."

But this is all academic at this point. It's clear, from hearing you try to explain your understanding of Everett in the vocabulary of computer software, that you are in way over your head. If you tried to talk about this in these terms to actual physicists, they will literally laugh you out of the room. And not kindly.
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Old 31st December 2020, 07:19 PM   #159
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Originally Posted by Mike Helland View Post
As far as levels of abstractions there are exactly two, which relate to Everett's absolute state and relative state:
No, that's not what level of abstraction means.

Quote:
The particle simulation contains a group of particles acting as microcomputer with a webcam and computer vision software.
No. That is nothing like what observation entails in quantum mechanics, by any reckoning.
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Old 31st December 2020, 07:58 PM   #160
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Originally Posted by JayUtah View Post
Okay, so first what you're talking about is a physics engine. A particle system is a particular technique within the general framework of game physics.
Ok.

I used the words "particle simulation".

Let's say we make a simulation of gravity. Let's add 30 objects with random positions and masses:

Code:
var objects = []
for (var i = 0; i < 30; i++) {
    objects.push({x: Math.random(), y: Math.random(), z: Math.random(), m: Math.random})
}
And the laws of physics, simple attractive force of masses multiplied over distance squared.

Say 28 of the objects go flying off into space, while two objects enter stable orbits with each other.

The objects array has 30 objects in it. But there's two that formed something that we can investigate.

This is what I mean by "sub-system of the particle simulation".

I assume that's what Everett means too.

Page 4

Quote:
For this purpose it is
necessary to formulate abstract models for observers that can be treated
within the theory itself as physical systems, to consider isolated systems
containing such model observers in interaction with other subsystems, to
deduce the changes that occur in an observer as a consequence of interaction
with the surrounding subsystems.

http://jamesowenweatherall.com/SCPPR...ttComments.pdf

Hopefully that clear that up.

Originally Posted by JayUtah View Post
This is immediately wrong. You think an Everettian observer requires photons, in essence that observation -- in the quantum mechanics sense -- is the same as literally seeing an object as you and I would.
Photons mediate the exchange of energy between electrically charged particles.

Without them atoms wouldn't stay together.

The problem here really seems to be that you are imagining what I think, and then attacking what you imagine.


Quote:
So the neural net is the literal eyeball in your model?
No, the web cam is the literal eyeball.

Quote:
Your notion of a "neural net" is that it's computer vision software?
OpenCV, which is computer vision software, employs a neural net.

If you prefer non-neural net based version of computer vision, you're welcome to use them all you want.


Quote:
So you say "particle system" when you mean "physics engine," and you say "neural net" when you mean computer vision.
You were the first to use the phrase "particle system".

Search the messages in this thread.

Quote:
You're still thinking way too literally.
You should give it a try.

Last edited by Mike Helland; 31st December 2020 at 08:01 PM.
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