Uncertain about uncertainty - and Zeno isn't helping!

[Hashi Lebwohl]

But... Look, I'm not arguing for anything I know anything about here. I'm just saying, if I show you a picture of a car, we can use the landmarks to determine exactly where it is. But you wouldn't be able to tell me how fast and in which direction it's going, or even if it's moving at all. If you try to tell me exactly where a moving car is in any given instant, you won't be able to. Not with absolute precision. Get out your ruler and tell me exactly how many mm it is from the curb, from the corner, etc, and you won't be able to. Because it's moving, and it will not be on that exact piece of pavement by the time you get your reading. Don't tell me where it was within X cm, but you can't be exact because it was moving and you can't tell me to within a thousandth of a millimeter where it was exactly that instant. I want EXACT.

Am I making any sense?

The picture of a car is not the car. Yes, that type of measurement has the limitation of fixing the car in space at only one precise moment of time. Velocity is (change in distance)/(change in time) so if (change in time) = 0 then velocity = (change in distanace)/0 which has the precise mathematical definition of "indeterminate"--we don't know how fast the car is moving. However, if using a radar gun we can know, exactly, where the car is located, which way it is going, and how fast it is going there.

[Fist and Faith]

Objects which have a mass sufficient to negate any Heisenberg limitation are subject to being measured or discerned without any noticeable effect. A radar gun does not impede an automobile, nor does it effect the direction or magnitude of its velocity.

Thinking about it the wrong way, really.

The properties of subatomic particles are indeterminate because they don't exist in a discrete state like macroscopic objects do - and we can only observe them through their interactions. It should be pretty obvious that any interaction means an exchange of energy in some way, changing the system under observation.

(It's not so much that the subatomic particles behave strangely, but that the macroscopic physics we're used to looking at are an emergent property that comes from viewing what's going on from too far away.)

This idea is a revelation to me. Seriously. As I just said about Relativity, I've never read much about HUP, because I've never been able to figure out what they're talking about. This might let me get another few paragraphs in the next time I try to read about it.

[Vraith]

But... Look, I'm not arguing for anything I know anything about here. I'm just saying, if I show you a picture of a car, we can use the landmarks to determine exactly where it is. But you wouldn't be able to tell me how fast and in which direction it's going, or even if it's moving at all. If you try to tell me exactly where a moving car is in any given instant, you won't be able to. Not with absolute precision. Get out your ruler and tell me exactly how many mm it is from the curb, from the corner, etc, and you won't be able to. Because it's moving, and it will not be on that exact piece of pavement by the time you get your reading. Don't tell me where it was within X cm, but you can't be exact because it was moving and you can't tell me to within a thousandth of a millimeter where it was exactly that instant. I want EXACT.

Am I making any sense?

well the question sure makes sense...and the answer is: you are not going to get exact. It is neither physically nor conceptually/theoretically possible [in current understanding] to do so. It's even worse: even if the car was completely motionless, you could not get your absolute precision on its position.
OTOH: unless your camera took the picture within a perfectly instantaneous moment, a "time period" of no duration at all, it's speed and direction [with the right equipment] could be determined [to near but not quite absolute precision]. EDITED to add: Even if your camera could do that "speed," though, it would I think be possible to tell IF it was moving. Perhaps even how fast.
But the difference between the absolute and the measurable, again, is so infinitesimally small on the car scale it is almost meaningless.
Oh...and the accuracy of those, with the right gear, would be much closer to exact than one thousandth of a millimeter you demand for position....
theoretically it could be within: .00000000000000000000000000000000016 millimeter. [IIRC...it might be .00000000000000000000000000000000008millimeter.]

[Avatar]

Everything is uncertain.

You sure about that?

Nope.



--A

[peter]

The properties of subatomic particles are indeterminate because they don't exist in a discrete state like macroscopic objects do

How does that happen. How is it that objects composed of indeterminate sub-units become determinate at the macroscopic scale. Is there like a 'cancelling out' of opposite indeterminacies when large numbers of things are grouped together rendering the macro object determinate, or is it something else that maybe cannot even be stated in non-mathmatical terms (and is thus forever inaccesable to a dunce like me ).

Another thing. When does it happen, this shift from indeterminancy to determinancy - at what size of object (or indeed what number of constituent sub-units if thats the criterea). Does it happen gradually or with a sharp boarder. Or are we talking two totally different sets of phsics here and never the twain shall meet. (If we indeed have no model that will pertain to all sizes of objects, does that seem a problem - I can't help but confess that it would to me. I've got a feeling the GUT may be what I'm talking here).

Sorry Guys - I'm aware I'm 'punching way above my weight' here but this stuff interests me. If I'm just talking rubbish ignore the questions and I promise I'll retreat to the sidelines and try to learn from what you guys have to say.

[Fist and Faith]

I could have written that post, peter. Great questions, for those of us who can't figure it out. Even after having tried this and that book and website, this stuff eludes me completely.

[Zarathustra]

The properties of subatomic particles are indeterminate because they don't exist in a discrete state like macroscopic objects do

How does that happen. How is it that objects composed of indeterminate sub-units become determinate at the macroscopic scale.

Now that's a good question. I'm not sure anyone can answer it. I believe it's one of the deep mysteries of quantum theory, and the reason why there are at least 8 different metaphysical interpretations of it--none of which are eliminated by the math or by experimental evidence.

Some people actually believe that the crucial event is looking at the object, and collapsing proxy waves of probabilitly into a single, determinate object. So the Moon doesn't have a position/velocity until someone looks up at it. An observer-created reality. It's for this reason that you have people pondering things like whether or not Schrödinger's Cat is dead or alive ... the uncertainty can be made manifest on macro scales in the right circumstances.

There is also the many-worlds interpretation, a competing model. This one splits off the multiplicity of possibilities into nearly identical copies of this universe, so that every possible attribute exists in one of these universes. Indeterminism is an illusion produced by the fact that we can't view all those other universes in which the attributes are determinate. But they actually exist somewhere.

Is there like a 'cancelling out' of opposite indeterminacies when large numbers of things are grouped together rendering the macro object determinate, or is it something else that maybe cannot even be stated in non-mathmatical terms (and is thus forever inaccesable to a dunce like me ).

I think this is on the right track. Remember, even the car's "position" only has meaning in regards to the reference frame: the road, the city, the country, the earth. But all these reference frames are themselves orbiting the sun, which is orbiting the center of our galaxy, which is flying away from every other galaxy, etc. What is position, really? It's a relational attribute measured against everything else. So it only has meaning in relation to everything else, the whole system.

So perhaps when many atoms interact to form a single object, their probabilies and indeterminism cancel out in virtue of their interaction. Perhaps that's exactly what their interaction is: a plethora of possibilities collapsing upon actualities in such a way that a single object (like a car) is formed. And then because our daily, mundane observations happen on the scale where this occurs, everything looks determinate.

Another thing. When does it happen, this shift from indeterminancy to determinancy - at what size of object (or indeed what number of constituent sub-units if thats the criterea).

That is another deep question. It's the measurement problem in quantum theory. Some people think it happens somewhere inside the measurement apparatus. Others think it happens within consciousness--that consciousness itself is a quantum phenomenon, a glimpse into a multiplicity-reality which can only take away one "slice" of that multiplicity. Others (many-worlds proponents) think that there is nothing at all special about measurement devices and that every possibility does actually exist in another parellel universe, so that a shift never actually happens between indeterminate and determinate, it only looks this way because we can only see one universe at a time.

I can see this really interests you, the deep questions of quantum theory. You are asking *the* most relevant questions. I highly recommend the book Quantum Reality by Nick Herbert. It deals with exactly the issues you've raised here, and explains it a lot better than I can.

[I'm Murrin]

The properties of subatomic particles are indeterminate because they don't exist in a discrete state like macroscopic objects do

How does that happen. How is it that objects composed of indeterminate sub-units become determinate at the macroscopic scale. Is there like a 'cancelling out' of opposite indeterminacies when large numbers of things are grouped together rendering the macro object determinate, or is it something else that maybe cannot even be stated in non-mathmatical terms (and is thus forever inaccesable to a dunce like me ).

I thought I addressed that part. They're not actually behaving like anything but themselves, it's just that when viewed from a distance (i.e, when observing from a "macroscopic" scale and not a fundamental scale) what we see is not the actual interactions but the emergent patterns created by those interactions.

[Vraith]

The properties of subatomic particles are indeterminate because they don't exist in a discrete state like macroscopic objects do

How does that happen. How is it that objects composed of indeterminate sub-units become determinate at the macroscopic scale.

Now that's a good question. I'm not sure anyone can answer it. I believe it's one of the deep mysteries of quantum theory, and the reason why there are at least 8 different metaphysical interpretations of it--none of which are eliminated by the math or by experimental evidence.

Some people actually believe that the crucial event is looking at the object, and collapsing proxy waves of probabilitly into a single, determinate object. So the Moon doesn't have a position/velocity until someone looks up at it. An observer-created reality. It's for this reason that you have people pondering things like whether or not Schrödinger's Cat is dead or alive ... the uncertainty can be made manifest on macro scales in the right circumstances.

There is also the many-worlds interpretation, a competing model. This one splits off the multiplicity of possibilities into nearly identical copies of this universe, so that every possible attribute exists in one of these universes. Indeterminism is an illusion produced by the fact that we can't view all those other universes in which the attributes are determinate. But they actually exist somewhere.

Is there like a 'cancelling out' of opposite indeterminacies when large numbers of things are grouped together rendering the macro object determinate, or is it something else that maybe cannot even be stated in non-mathmatical terms (and is thus forever inaccesable to a dunce like me ).

I think this is on the right track. Remember, even the car's "position" only has meaning in regards to the reference frame: the road, the city, the country, the earth.

Somewhat randomly addressing things in this section:
If anyone has come up with a way to describe the "objects" accurately other than mathematically, I'm not aware of it...if you don't "speak" or "see" math, some things will forever be silent/invisible. I freely admit to being in that group...kinda like I'm enough of an artist to draw a sloppy stick-figure of a person. I suspect that a complete non-math description may not even be possible because [similar to what Murrin is saying, I think] the "objects" are not "objects" in any ordinary sense. Just one "for instance" of it and sticking with cars...we can be outside the car, then through a process...including moving through space...enter, then be in the car. These objects can be in the car or out of the car but in between do not [cannot] "get into the car." In or out is all there is. [pretending they have only 2 possibles, and analogizing the "states" to in or out.] But this is important, I think, in talking about the shift from micro to macro. In relation to each other, these objects don't have unlimited possibilities, they have boundaries...certain states that they simply cannot have. And the larger the number of relations/interactions they have, the more limited those possibilities become...so that by the time we have a car there are so many limits from so many sources/forces that the car seems determined, reliable, measurable in lots of ways. But...I think this is really so, but the guy who told it to me years ago likes his little jokes...there is a non-zero chance the car could vanish [probably in a massive release of energy that should probably only be observed from very far away]. That's a translated explanation given to me some time ago...one neither precisely collapsing waves nor many worlds. And it has the advantage of lightening the burden on us beings imposed by a total "observer-created reality." It allows for the moon to have position/velocity without making sure someones watching it all the time. Same guy gave me a couple others, but I understood them much less even than this one and the ones already discussed.
Many worlds one just freaks me out...an infinite number of universes exactly like ours except for one electron somewhere in one different state, for example. Crazy. And doesn't that mean every single time one thing happens, not matter how small, at that instant a new one springs up, already fully formed, for every possible thing that could have happened? Does that mean those universes are born immediately 13billion years old? Does that also imply an infinite number more with 2 total state differences? And then 3? Up to an infinite number where all states are different? Or is all that covered in the initial formula?

[Fist and Faith]

I've posted this before. A great moment from Big Bang Theory. Penny and Leonard are planning to attempt a romance, and Penny asked Sheldon what he thinks about it. (Who can imagine why anyone would ask Sheldon about such a thing, but...)
www.youtube.com/watch?v=HCOE__N6v4o

But this clip skips a scene between the two in the clip, when Leonard asks what Sheldon thinks.

Sheldon: "Schrodinger's Cat."
Leonard: "Brilliant!"

[Avatar]

How does that happen. How is it that objects composed of indeterminate sub-units become determinate at the macroscopic scale.

Fist actually knows this one. Habit. Imagination. Assumption. You think that floor you're standing on is solid? It's determinate, sure. But mostly because you expect it to be.

...but the emergent patterns created by those interactions.

That was extremely well put Murrin. Well put indeed.

There is also the many-worlds interpretation, a competing model.

Everett-Wheeler-Graham model? I like alternative realities, but I think the waveform collapse is more believable.

--A

[peter]

Thanks Guys

The book sounds great Zarathustra. I've read a few 'popular science' books in the physics area and slowly (very slowly I admit) it's starting to come together in my head. Trouble is each time I think I get a handle on any particular bit something else comes along and I forget the thing I thought I had grasped previousely. It's like trying to catch eel's in a bucket. (Witness Murrins perfectly good explanation that flew past my ear like a paper plane in a classrom - sorry about that M. ).

[Shaun das Schaf]

I've posted this before. A great moment from Big Bang Theory. Penny and Leonard are planning to attempt a romance, and Penny asked Sheldon what he thinks about it. (Who can imagine why anyone would ask Sheldon about such a thing, but...)
www.youtube.com/watch?v=HCOE__N6v4o

But this clip skips a scene between the two in the clip, when Leonard asks what Sheldon thinks.

Sheldon: "Schrodinger's Cat."
Leonard: "Brilliant!"

And continuing their theme, a recent episode featuring Wil Wheaton and Brent Spiner, had Schrodinger's Friendship. Sheldon's 'dead and alive' approach to Leonard had me cacking heartily. Did you see this ep?

[Fist and Faith]

I'll look for Quantum Reality by Nick Herbert. Probably today, but I'm on vacation for the next sixteen days , so plenty of time. But I suspect Quantum For Dummies, and likely Physics For Dummies would be a better starting point.

My wife and I watched a Nova program last night.
The Fabric of the Cosmos: The Illusion of Time
Written and narrated by Brian Greene. It was fun, though largely over my head. I understand more of what happens, how the universe actually works, but I've never had the slightest understanding of how it does it. I've long understood that time moves at different rates for things that are moving at different speeds. And for things at different places, like at the top of a skyscraper and the bottom of the skyscraper. The implication I got last night (assuming I got it right), is this:
Let's say there's an alien on a planet 10 billion lightyears away. If we had telescopes capable of seeing each other's planets, we'd each see 10 billion years into each other's pasts. But if these telescopes could see exactly this moment on each other's planets, we could stand at our telescopes and wave at each other. The "now" of the universe is me sitting at the telescope, that alien sitting at that telescope, and a gajillion other things in the universe. BUT, if that alien started moving toawrd me, when it looked into its magic telescope, it would see 200 (or whatever) years into my future. The "now" of the universe for that alien does not include me, now.

There is not one, official, objectively accurate "now" in the universe. There's never such a thing. (Except, I suppose, at the moment of the BB.) This applies to all of us here on Earth, also. But our speeds relative to each other compared to the spee the speed of light, and the different amounts of gravity we experience at different elevations here on Earth, are so tiny that our different "nows" aren't different enough for our senses to detect. It's insignificant. On the scale of the universe, though, the nows of that alien and I end up centuries/millennia apart.

So that's what happens. All well and good. It's been proven countless times. But I still don't have the slightest idea how it happens.

[Hashi Lebwohl]

The "macroscopic" scale is still pretty darned small. Very large carbohydrate chains or protein molecules follow Newtonian physics more than they do quantum physics, so the cutoff point would have to be smaller than that.

As to why this happens...I suspect it goes back to the waveform collapse that Avatar mentioned. Above a critical threshold of mass and energy, the wave equations of an object actualize from a field of probabilities into only one solution.

Physicists working with near-absolute-zero temperatures, though, note that atoms start to have a more wave-like nature than particle-like nature; below a critical temperature, the wave pattern of atom A will intersect the wave pattern of atom B--at this point there are not two atoms but only one thing that fills the volume of space defined by their joint probability fields and quantum behavior begins to be evidenced at the macroscopic level. That is truly weird.

[Vraith]

My wife and I watched a Nova program last night.
The Fabric of the Cosmos: The Illusion of Time

Crap! I missed that...didn't even know it was going to be a kind of mini-series.
I saw the first part. It was "What is Space?" and I found it very very cool. The next two are about quantum and then universe/multiverse. I'm going to hulu, see if they have the one you saw.

Edited to add something really weird from the "space" episode. Talking on the fairly recent, and very surprising, discovery that not only is the universe expanding, which we knew...it is accelerating in expansion. So one approach to the reason for this is that "empty" space has some kind of material reality. And [this is a quick, not precise paraphrase, with many things left out you should watch it] because space is getting "larger," "more of it" it is pushing outward harder, against gravity, which is trying to pull things in. And space is winning.

[Fist and Faith]

I didn't know anything about it until we saw this. Gotta look for the rest.

[Fist and Faith]

Don't remember where you are, but the one I saw is on again here Sunday.

[Hashi Lebwohl]

Some cosmologists hypothesize that gravity is a "spill-over" force that leaks into this dimension from one of the higher dimensions we cannot perceive. This would explain why gravity has infinite operational distance yet is the weakest force--even small magnets can overcome gravity.

[Vraith]

Some cosmologists hypothesize that gravity is a "spill-over" force that leaks into this dimension from one of the higher dimensions we cannot perceive. This would explain why gravity has infinite operational distance yet is the weakest force--even small magnets can overcome gravity.

Is that part of one of the string-versions and the extra dimensions they need, or an entirely separate theory?

Don't remember where you are, but the one I saw is on again here Sunday.

I'm everywhere, all the time, just like it says in my profile column thingy to the left.
<----------
[you may be asking "why, if that is so, why don't you understand all this stuff completely, and how did you miss the episode?"
I wasn't at home, I was in a different quantum state, their service providers don't carry Nova. Something about FCC and broadcaster rules.
I know, paradox. Or at least weird. Sorry to give you another one.