This sure is a fun conversation! :-)
Actually, I just hit the "clear" button on my keyboard accidentally, merely lines away from completing the post…Forrest, fix that now ::angry at world:: So, I'll just skip to the chase in most of what I say.
: Well...kinda. See, the thing is that "mixed" is
: a relative term. A system isn't just in a mixed
: state...it's in a mixed state with reference to some
: property. Which basically means that when you apply
: the appropriate transformation for that property to
: that system's wave function, the transformed function
: is not an infinitely-thin spike around a certain
: value, but rather is "smeared" over multiple
: values or a continuous range.
Aye, it's a limitation of our technology.
: So, really, systems are always in mixed states with
: reference to *some* properties. When you measure a
: certain property of a system, you collapse its wave
: function into a state which is unmixed with reference
: to that particular property, but now it's mixed with
: reference to other properties. This is another way to
: think of the uncertainty principle...it tells you, for
: a given pair of properties, how badly measuring one of
: them will mix the system's state with reference to the
: other.
: Which is really freakin' weird, I fully admit. But the
: actual predictions are borne out by experiment...and
: there're certain experiments which really can't be
: explained away by any common-sense alternative. Here's
: an example.
Which is why we need to theorize about a solution to the problem rather than following QM so blindly.
: In QM, some particles have a property called
: "spin." This is closely related--but not
: equivalent--to their angular momentum. Now, spin is a
: vector, with X, Y and Z components. There's an
: Uncertainty Principle variant for any two spin
: components which says that the product of their
: measured uncertainties is *infinite.* Which basically
: means that if you know *anything* about one component,
: your measurement of the other one will give a
: completely random answer.
Something else is going on here.
It's either a conspiracy of God and the universe, our technology is too limited, or there is something very strange underlying the universe.
: So how do you test this? Well, you can start with a beam
: of particles you *know* all have the same X-spin
: value. (Fire a particle beam through a magnetic field
: in the X-direction--it'll split into multiple beams,
: each with a single X-spin value.) You can then measure
: the particles' Z-spin in *any* way you want. Simplest
: way is to split the beam again with a magnetic field
: in the Z-direction. Now measure the particles' X-spin
: values again in any way you want, and whaddya know? A
: bunch of the particles will now have changed their
: X-spin values so that there's roughly equal numbers of
: particles with any possible X-spin value. This has
: happened for *every* possible way we know how to
: measure spin.
We need a new way then :-).
: Now it's probably possible to come up with a clever
: explanation of why this happens when you do magnetic
: beam-splitting, but when it happens using other
: methods as well? Similarly, there's a ready
: explanation for the position-momentum Uncertainty
: Principle when you're just thinking about measuring
: stuff by bouncing light off it, but for decades
: physicists have been trying to think of new and
: ingenious methods of getting around the Uncertainty
: Principle by measuring in other ways. Passive sensing,
: shining light around the particle and looking for a
: "shadow," interference patterns...they never
: work. So why not accept the Uncertainty Principle
: until some clever bastard *does* manage to break it?
: Just as we accept the light-speed limit, or
: conservation of energy?
: Well, no, it's not proven wrong. How would you go about
: proving such a thing as where an object
: "really" is in the first place? Philosophers
: have argued over whether objects "really"
: even exist for millennia.'
I thought *someone* believed that one such a prominent figure who said those things was a crazy, vegan bastard. :-)
Figments of the gods' imaginations indeed…
To quote a miscelaneous philosopher, ::stamps ground:: This is real!
: Now if you take the "minimalist" worldview
: implied by quantum mechanics--which you don't have to,
: it's a philosophical choice-
Aye, but one should, or otherwise be hypocritically not believing in the "facts" they dictate when applying themselves to the tangible world.
:-then what QM is really
: saying is that things like "location" and
: "momentum" don't have any solid meaning. The
: "real world" is made up of wave functions,
: and the way we observe it is to poke the wave
: functions with measurement apparatuses and see the
: data they return. We don't directly "see"
: the properties the wave functions have, but we get
: hints at them from the properties of the data we
: get--which we label as location and momentum and so
: forth.
: Really, is this so absurd?
Yes! but not unbelievable :-).
: Is it so strange to think of a
: world where we can't see what's really going on? After
: all, you can't perceive an electron, or an atom...you
: can only perceive an image produced by a brain state
: produced by a retinal impulse produced by a photon
: emitted by that electron or atom. We could never hope
: to perceive any system (other than our own thoughts
: and sensory perceptions) directly, unless we're God.
Human perception is through the senses, and mb through the mind. Anything else is not who we are, and we are otherwise not experiencing.
: And is it strange to think that you always affect a
: system by observing it? What sense *doesn't* work that
: way? Can't see something without bouncing light off
: it...can't hear it without bathing it in gas and
: making it vibrate...can't smell it without pulling
: molecules off it and sending them into the air. Even
: the most abstract types of perception--such as feeling
: its gravitational pull--require, by Newton's 3rd law,
: that the object get pushed too. QM doesn't add much
: new to this.
: Got to be careful when you say it "can't
: predict" stuff...there are a number of ways that
: term is used.
Can't predict it accurately.
: In theory, QM can most certainly be used to predict the
: normal universe.
WIth many oddities, yes.
: It doesn't get stuff wrong until
: you're operating on areas the size of the solar
: system. Which, believe me, is as wide a range of uses
: as any physical theory has. General relativity is just
: as bad at small-scale stuff as QM is at large-scale
: stuff. But they're both far more widely valid than
: classical mechanics and E&M or any other physical
: theory--and between them, they damn near cover the
: universe.
I have a GUT feeling something else is coming along…
: The reason why we don't use QM on human scales much isn't
: because it gets stuff wrong there...it's because the
: calculations are absolutely horrendous. Look at
: physics and chemistry. The entire science of chemistry
: is, in theory, inaccurate and unnecessary. All you
: need is for physics to tell you exactly what each
: particle in a chemical solution will do at any given
: time...then put 'em all together and you know what the
: whole chemical process is.
: But in *practice,* of course, this is ridiculous. No
: human or computer can possibly analyze large-scale
: chemical reactions by looking at every single atom. So
: we use "sloppy" statistical rules of thumb
: instead...and this makes up the "science" of
: chemistry.
Sloppy? Woh! You never saw my classes! HoHO!
: Similarly, there's no point in using QM to figure out the
: mechanical properties of, say, a bicycle, because
: you're going to be doing an insane number of
: calculations. Much better to cheat a bit and use
: classical mechanics...it's wrong, of course, but not
: wrong by enough to matter.
Aye, aye…
: You sneaky devil.
^ ^
\ /
° °
|_|
: Of course something better than QM will come along.
: That's how science works. You use a theory until
: something better turns up...at least until we get our
: Grand Unified Theory and it all screeches to a halt.
: :-) But I was serious about Bell's theorem...it really
: does show very very convincingly that the time of
: determinst theories is at an end. Wave Functions Are
: Your Future.
: As for GURPS...I will gladly toss it aside in the face of
: any empirical facts...that is, things that come out of
: the mouths of Rob McLees and his little buddies. :-)
You're a stubborn one, Dream, I'll give ya that. Ok, you live in your Sili little world, and we'll have fun, k? :-D
: Careful...you'll convince every physics student on the
: forum that the Deceiver lives. :-)
::finds no one else:: Lol, you already are, Sili!
: --SiliconDream, nobly slogging through atlan.org and the
: Anthro library
Yay!
