
The “uncertainty principle” is a mis-translation (2014) - lisper
https://www.edge.org/response-detail/25531
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sparky_z
My favorite explanation comes from Greg Egan[0]:

"The uncertainty principle is the inability of a quantum system to possess
sharply defined values of certain pairs of variables, such as position and
momentum. Unfortunately, this simple fact is sometimes shrouded in confusion,
some of which probably dates back to a famous thought experiment of
Heisenberg’s in the 1920s. Heisenberg pointed out that, because light comes in
quanta with a minimum amount of energy and momentum for any given wavelength,
even if an electron was a point particle straight out of classical physics, we
could never illuminate one in order to see where it was without disturbing it
to some degree in the process. This is a perfectly true statement — but it’s a
true statement about a hypothetical alternative universe, because electrons
aren’t classical point particles. A correct description of an electron,
whether as a wave function in ordinary space or a state vector in a Hilbert
space, shows that it doesn’t need to be “disturbed” by anything in order to be
subject to the uncertainty principle. It simply can’t possess an exact
momentum and an exact position at the same time, any more than a musical note
can be a perfect middle C, giving it a well-defined frequency, while lasting
for a billionth of a second, giving it a well-defined location in time."

[0]
[http://gregegan.customer.netspace.net.au/FOUNDATIONS/04/foun...](http://gregegan.customer.netspace.net.au/FOUNDATIONS/04/found04.html#s5)

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pmiller2
> A correct description of an electron, whether as a wave function in ordinary
> space or a state vector in a Hilbert space, shows that it doesn’t need to be
> “disturbed” by anything in order to be subject to the uncertainty principle.

This is, in fact, a result of the uncertainty principle of Fourier analysis.
See
[https://en.wikipedia.org/wiki/Fourier_transform#Uncertainty_...](https://en.wikipedia.org/wiki/Fourier_transform#Uncertainty_principle)

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EnFinlay
I'm not following how "uncertainty" principle is a bad way of putting it. No
matter what we do, we cannot know the position and velocity precisely at the
same time. If you know position precisely, velocity is uncertain. From what I
understand it's not a matter of velocity is "as yet undetermined", if we know
the location precisely, then the velocity has many values and will collapse to
one value if observed precisely (at which point position will have gone from
precise to many valued).

Or should I not be physics-ing in the morning.

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Florin_Andrei
"Uncertainty" suggests that the position might, in some way, be defined with
100% precision, but it's us, the observers, who are uncertain what the actual
value is.

"Unschärferelation" suggests the value coming out of the system (position,
impulse, etc) is in a fundamental way not pinned on a single value fixed with
100% precision, but instead it's spread out over a distribution function.

~~~
EnFinlay
Oh, I got it. It's the difference between "I am uncertain" and "It is
uncertain". That makes sense.

First discussion that happens in an undergrad quantum mechanics class.

Teacher: "It is uncertain" Student: "Can't we measure it better?" Teacher:
"No, it is unknowable, no matter what" Student: "Wtf?"

~~~
emsy
Unscharf (the adjective to Unschärfe) can be translated to "out of focus" or
"blur", which kind of describes the phenomenon figuratively.

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gaur
> which transliterates to “unsharpness relationship,” but as there is really
> no such term in English

Seems like there is: "unsharpness relationship".

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deepnet
> "Unbestimmtheit" (Indeterminacy) was on the part of the observer: not
> realizing certain aspects of nature at this stage in our knowledge—rather
> than proof that nature itself is fundamentally undetermined and uncertain.

And yet Bell's theorem and Aspect's experiment show there are no hidden
variables.

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taneq
If I understand this guy right, he's basically saying that the uncertainty
principle is just a statement about our ability to measure things, rather than
a statement about the actual reality about what variables (hidden or not) are
stored by each particle.

I used to think the same, and intuitively this still seems right to me, but
apparently there's been a bunch of experiments based on the Bell Inequality
that prove that we're wrong.

~~~
gandarojin
No, I do not think that you are understanding him correctly. What makes you
think that?

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taneq
Just one example from the article:

> rather than stating that either position or momentum are "as yet
> undetermined", it became common usage and popular wisdom to jump to the
> conclusion that there is complete "uncertainty" at the fundamental level of
> physics

Can you explain how you drew any other conclusion from the article? The whole
thing is driving at this one point.

~~~
gandarojin
His position is ‘that either position or momentum are “as yet undetermined”’.
That means that the ‘uncertainty’ is not due to our ability to measure things,
but ‘rather […] a statement about the actual reality about what variables
(hidden or not) are stored by each particle’. :)

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llamaz
Is there actually a thing in physics where you change the measurement by
observing it?

I do electrical engineering, and as far as I know, the uncertainty principle
means that as the signal in the time domain gets more localized, the signal in
the frequency domain gets more spread out (and vica versa). I think ( I don't
know for sure) position can be thought of as time domain and momentum can be
thought of as frequency domain (or it might be the other way around).

I'm not sure if this relationship actually leads to the Futurama "No fair, you
changed the outcome by observing it!"

I could research this to find an answer, but it would take me way too long.

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tbabb
Observer effect.

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llamaz
Thanks :) That gives me something concrete to google

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sandworm101
My favourite scientific mistranslation: Alien hand syndrome.

[https://en.wikipedia.org/wiki/Alien_hand_syndrome](https://en.wikipedia.org/wiki/Alien_hand_syndrome)

The original French is "Syndrome de la main étrangère", which should be called
"stranger's hand" and describes a condition where brain injury may result in
unwanted movements of a hand.

[https://fr.wikipedia.org/wiki/Syndrome_de_la_main_%C3%A9tran...](https://fr.wikipedia.org/wiki/Syndrome_de_la_main_%C3%A9trang%C3%A8re)

~~~
flubert
In what sense this a mistranslation? If you conflate alien with extra-
terrestrial?

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SilasX
In current usage, people almost exclusively use "alien" to refer to ETs. The
only ones who use it in the sense of "foreigner" are immigration bureaus, and
this becomes a source of hilarity whenever they speak to the outside world.

Would you ever say "I had some aliens in my home last night for dinner" and
expect someone to interpret that to mean immigrants/tourists/strangers? At
best, they would criticize you for using that term to refer to them.

~~~
flubert
Illegal Alien gets quite a few hits on google.

[https://www.google.com/#q=illegal+alien](https://www.google.com/#q=illegal+alien)

~~~
SilasX
Perhaps I should have said "immigration law enforcement" instead, but the same
point. Outside the that context, "alien" means ET.

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Retric
This may be a case where the translation ends up more accurate. 'Observer' is
really just any other wave/particle. So, this is in terms of all outside
perspectives not just machines/scientists.

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astazangasta
I remember the first time someone explained to me that the uncertainty
principle was just a fact of waves. Decomposing a single event into frequency
space makes no sense, and neither does the inverse, taking a frequency (a
succession of regular events) and expecting it to have instantaneous meaning.

When I heard this I felt a profound sadness. After I was told it seemed
obvious, simple, intelligible, and the idea of a great cosmic darkness, Chaos
disordering and underpinning the universe, had vanished and been replaced by a
plain mathematical relationship. Alack.

~~~
lisper
How odd. When I grokked the uncertainty principle (and later, entanglement) I
felt a profound sense of euphoria and peace, because the world suddenly made
sense. Can you elaborate on why achieving this understanding made you sad? Why
is it so important to you to have chaos and disorder?

~~~
astazangasta
Hard to say - it was a visceral reaction that mostly manifested as a brief
resistance to the idea ("no, that can't be right"). I imagine some component
of my thought wants a space in the universe that is claimed by mystery. I
enjoyed reading Heisenberg's "Physics and Philosophy", where he discusses the
quixotic nature of the double-slit experiment and so on, notably things like
observation collapsing the wave function and removing the diffraction pattern.
Heisenberg definitely colors these things with an air of mystery, the idea
that the operation of the universe flies in the face of what we think of as
sensible. I'm someone who has always enjoyed being on the margins,
questioning, overturning, poking at consensus. Before I understood the
uncertainty principle I think it was a door to a much blacker mystery, and
thus a much greater rejection of the notion that "we understand", which I
think is something I have always associated with evil, hubris, and folly.

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eternalban
I think the OP is conflating matters that were originally conflated by the
theoretical community. Aspect makes the point that until '82 even Feynman did
not note the distinction between wave/particle duality and entanglement (only
the latter demands non-local aka "spooky" action.) It was only after Bell, et
al that e.g. in '82 Feynman recognized the distinctions and per Aspect
"typical Feynman he then invented Quantum Computing".

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dnautics
The theory of relativity is an misleadingly phrased concept - it should be the
"theory of absolutivity" \- because the relativeness is not the new part
(galilean and newtonian relative reference frames had been around for
centuries) it's reconciling it with the absolute speed of light which was the
new part, the part that introduces tricky math and "strange" concepts that
don't jive with our day-to-day sensory experiences in physics.

~~~
klodolph
I can't agree with the argument that "relativeness is not the new
part"\--since relativity introduces the idea that measurements of time and
space (and mass, electric fields, magnetic fields, etc.) are relative to the
reference frame. Classical mechanics only admits relative measurements of
velocity (and energy, momentum, etc).

But if you want to rename it, Einstein said that he should have named it the
Theory of Invariance. I'm fond of "relativity" because it admits adjectives
like "relativistic". We can say, "At relativistic speeds."

~~~
dnautics
well popularly (non-scientifically) relativity is thought to mean that a
measurement is relative, and that's generally an older concept than Einstein,
even though classical mechanics have a more limited scope of quantities that
are measured relatively (position, velocity). There are still things in
einstein's theory of relativity that aren't relative, even which would have
been relative in the classical system (the speed of light). And the initial
math outlays (lorentz transformations) are exactly as I described them,
shutting down the possibility that the speed of light is relative, creating an
"absolute" measurement.

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klodolph
What you are describing as "absolute" is described in the literature as
"invariant", which might help if you are doing web searches for more
information. "Absolute" usually has a different meaning.

