A rant : Magic (possibly Spirituality to)

[The Good Reverend Roger]

But only if it was a non-local cat.

The out of town ones are worse?   

[LMNO]

So anyway - this uncertainty thing, it's more to do with the fact that we can't actually tell it's precise location rather than it has more than one?

The Schrödinger field pattern in position space determines where a detection event is likely to be found, and its pattern in wavelength space determines the momentum we associate with the object causing the event.

If the events are localized in a small region, the wave pattern will be localized but consequently it will contain many elementary waves – its momentum will not be well-defined.

Conversely, if the momentum detector clicks only for a narrow range of momentum values, the wavelength is well-defined, and the wave pattern must extend over many cycles – its location in space is not well-defined. You can have waves with well-defined position or well-defined momentum, but not both at once.

...

As I see it, most problems of interpretation are resolved by the simple fact that the microscopic theory does not refer to any physical waves or particles. It refers to well-defined detectors and unambiguous events of detection. Accounts that ascribe position to particles and momentum to waves apply macroscopic language inappropriately to microscopic nature.

You can set a detector to register an event with well-defined momentum, or you can set it to record an event with well-defined position. That does not entitle you to say that the event is caused by a "wave" or by a "particle."

So, you can take one measurement, which will tell you where it is.  But one measurement can't define a wavelength, which tells you how fast it's going; for that, you need a lot of measurements.


So, you can either measure a point, or you can measure a wave, depending on what you're looking for.  But that just tells you what sort of measurement you're making. 

[P3nT4gR4m]

So the whole deal is about conventions in the maths to account for shortcomings of the measurement apparatus? 

What about the double slit thing, does that still behave maghwiqueally?

[LMNO]

Nope.

The observer ALWAYS decides what to measure.  ANYTHING you measure depends on the setup -- there's a very broad principle of relativity at work here.  You always have to have a coordinate system, a framework, or measurement doesn't make any sense.  What's interesting about quantum mechanics is that the choices of frameworks include much more than just coordinate systems -- they include whether you're going to measure position, or momentum, for example.  In QM, choosing one or the other is exactly like choosing one coordinate reference frame or another.  Nature will look different from these different perspectives.

In the "double slit" experiment, two completely different procedures are described.  Choosing one of them amounts to choosing a coordinate frame in which to view the system.  But nature still gets to decide what you see -- you don't actually create the natural phenomena, you only create the framework for it.  Nature's choice shows up in the part of the experiment where you decide to look inside the boxes.  You will never find a particle in both boxes.  You'll find it in one or the other.  Nature gets to decide which one.  You can't affect that.  All you do is put the boxes there and decide what to do with them. 

You create the conditions for the results, but not everything is under your control.  The two kinds of experiments, by the way, differ exactly in the things that the uncertainty principle says you can't measure at the same time.  The interference experiment measures a wave property (momentum), the experiment where you look in the boxes measures position (where the entity is).

[Golden Applesauce]

Here's an easy way to think of it:

A lot of the bizarro stuff of QP stems from the fact that uncertainty in position times uncertainty in momentum is greater than a small constant.  Uncertainty is measured in absolute terms - it's not +/- a few percentage points, it's +/- a few nanometers.  Which means that it doesn't scale - knowing that an electron is within a nanometer of there describes a small cloud of where the electron could be.  Knowing where a person is to within a nanometer is an impressive feat of measurement in and of itself.  The uncertainty due to quantum is negligible because it's less the the uncertainty of our instruments anyway.  Being able to be in two places at once on the precondition that both places must be within a nanometer of each other is a very, very lame superpower.  Also remember that the other component of the uncertainty is momentum, which is mass times velocity.  For a very massive body (compared to an electron; if you stuck 20 zeroes on the end of the mass of an electron, it still wouldn't be a gram of mass, so what we consider to be "normal" is incredibly massive relative to an electron - even a proton is 2000 times the mass of an electron), even a tiny tiny tiny uncertainty in velocity, once multiplied by mass, is big enough that you can get by with an even tinier uncertainty in position as well.  So we can know the position and velocity of a person to more accuracy than anybody would ever need without getting close to the quantum limit.

That was all mostly wrong, but if it helps anyone avoid scams, then go for it.

For some reason this whole notion just caused me to laugh so hard I shit myself out loud.

I'm picturing "Captain Quantum" and he's kinda like "The Tick" but without the antennae and dressed in pink  

So anyway - this uncertainty thing, it's more to do with the fact that we can't actually tell it's precise location rather than it has more than one?

It's worse than that - it doesn't even have a precise location until a measurement event, and it likewise doesn't have a precise momentum until a measurement event.  The problem is that a well-defined momentum is exclusive to a well-defined position.  It's not just that we can't measure both at the same time, it's that particles waves things fundamentally can't have both at the same time.

Think of a wave/particle as being a rectangle with a minimum area, drawn on a Cartesian coordinate plane.  The horizontal axis represents position, and the vertical axis represents momentum.  The rectangle describes possible positions or momenta that the wave/particle could have - if the horizontal part of the rectangle goes from x=1 to x=3, then the position could be anywhere from 1 to 3; if the vertical part of the rectangle goes from y = 0 to y=4, then the momentum could be anywhere from 0 to 4.  The wave/particle doesn't really "have" a position unless the width is zero - if the rectangle extends from x=2.3 to x=2.3, then the particle has a definite position of 2.3.  If it just has a range of possible positions, all that means is that if we were to measure its position, we would get a result somewhere in that range, not that it actually is at one of those positions.  We can squish or stretch this rectangle as long as we keep a certain minimum area, so if we get a better idea of where the particle could be by squishing the width to only cover from x=2 to x=2.5, then we would have to stretch the height to compensate (thereby making the momentum more uncertain, for example from y= -2 to y=10 gives us an area of 12, the same as the rectangle from x=1 to x=3 and y=0 to y=4.)  Smooshing the rectangle to a width of 0 (as in the x=2.3 example) requires making it infinitely tall, from y = minus infinity to y = positive infinity.  The rectangle can't have a width and height of 0 (that is, well-defined position and well-defined momentum) at the same time, because there is a fundamental minimum area that the rectangle must occupy.

ETA: To tie that in with LMNO's quote, choosing which framework to measure is like choosing whether to squish the rectangle vertically or horizontally.

[The Good Reverend Roger]

It's worse than that - it doesn't even have a precise location until a measurement event, and it likewise doesn't have a precise momentum until a measurement event. 

Fucking cheating-ass universe.   

[Epimetheus]

it doesn't even have a precise location until a measurement event, and it likewise doesn't have a precise momentum until a measurement event.

I've heard/read that before, but how was such a thing found out?

[NotPublished]

[Prelate Diogenes Shandor]

Your definition of magic is too broad.

Science is NOT magic.

No, but according to Clarke's Third Law, sufficiently advanced technology becomes functionally indistinguishable from magic. At least superficially...

[The Johnny]

Your definition of magic is too broad.

Science is NOT magic.

No, but according to Clarke's Third Law, sufficiently advanced technology becomes functionally indistinguishable from magic. At least superficially...

I refuse to get involved in debating in this shitstorm of a thread.

[The Johnny]

                                                                      I DO THIShhh FOR SChhhIENChhhEEEEE !1!!!
                                                                      /
                                                                    /
                                                                  /

[The Johnny]

                                                                     Moonwolf Ravenaether, notice how the love                                                                                                                         potion reacted to the spell incantations
                                                                  we made during last months crescent moon?
                                                                      /
                                                                    /
                                                                  /

[The Good Reverend Roger]

                                                                     Moonwolf Ravenaether, notice how the love                                                                                                                         potion reacted to the spell incantations
                                                                  we made during last months crescent moon?
                                                                      /
                                                                    /
                                                                  /

If the world wasn't full of stupid people, this thread would end now.

[The Johnny]

                                                                       WITH THIS ENCHANTED PENTAGRAM
                                                                      I MAKE WOMEN DESIRE ME
                                                                      AND MEN TO FEAR ME
                                                                      /
                                                                     /

[The Johnny]

I PUT INCANTATIONS TO THESE IMAGES, SO THAT I CAN BANISH THIS THREAD TO MOTHER GAIAS DEEPEST BOWELS !1!!