Talk:Uncertainty principle

Observer Effect

Is the quoted statement correct? Didn't the modern double-slit experiment, conducted sometime after the sited reference, reveal that it was not simply detecting the particle that collapsed the wave function but rather the observation of the result? Please help!

"It must be emphasized that measurement does not mean only a process in which a physicist-observer takes part, but rather any interaction between classical and quantum objects regardless of any observer." — Preceding unsigned comment added by 2a02:c7d:784d:5500:2c4b:22cc:fce5:28c0 (talk)

The ideal of the detached observer -iatrogenic Building Blocks

Hello there. In the section entitled 'The ideal of the detached observer', though Pauli mentions that he disagrees with Einstein's refutation of the uncertainty principle with respect to the observer influencing the thing observed, adding that he hopes his memory accurately reported their conversation, we do not hear Pauli's corrective to Einstein's attempt to refute the idea of something changing while/upon being observed. I'm sure his recall was perfectly good and it probably doesn't matter as the example cited, the position of the moon being unchanged whether we observe it or not (a bit like Bishop Berkeley's kitchen vanishing once he moves into the living room) is exactly (with all due respect to Einstein) the wrong scenario with which to test the hypothesis. A simpler scenario whereby an inspector is observing a junior teacher teach captures the theory a little more firmly. The inspector's presence distorts the lesson being given though s/he perhaps is unaware to what extent his presence changes the thing that he is observing. Descartes x/y axis assumes a new dimension Z, 'the catalytic observer' or perhaps better 'the subjective correlative' (to finesse T.S. Eliot), it seems to me (though I know nothing about physics). Another scenario might see an art gallery visitor standing before a classical painting and then an abstract painting, the former demanding no participation to consummate its meaning, the latter requiring some. (Unwelcome to settled tastes, the idea of the public participating in art is anti-elitist but nonetheless considered a necessary corrective to self serving elites.) Likewise, developments like Le Nouveau Roman require readers to augment their missing chapters to complete them, thereby assigning or allowing a role for the reader/observer (as Detective fiction does). These simple examples are part of an index of much heavier (complex) applications with respect to the manner in which our judgement is or becomes skewed in certain situations where we passively participate in let's say condemning lust while living a life of unwelcome and enforced celibacy. Our often failure to see that our own pathology (sorry) influences our view of the thing observed can get us into all kinds of trouble. Psychoanalysts have something called the object oriented question which is 'employed' on particularly resistant/ repressed individuals who will only surrender an image of their ego unwillingly and so such people speak through objects (as we all invariably do) to express themselves, so enabling the therapist to get an idea of their psychic composition. The therapist him or herself may possess all kinds of blocks to observing the patient in a clear light. These iatrogenic blocks provide a term which may help differentiate between Einstein's Moon and more subtle examples where the presence of the observer does impact the thing observed. So, I think this section needs a little finessing to either include Pauli's refutation or a better example might be found to expound the actual beneficial application whereby a scenario is altered by virtue of being a participant. I hope I haven't confused matters. Thank you. M.H. p.s. If you doubt the role of the observer, consider the oft told story of King Faisal waking disguised in the market to find out what his people were thinking, and saying. He knew that if he showed up as himself, he'd get a very different reception. 'The Deferential Equation', maybe. — Preceding unsigned comment added by 37.125.41.223 (talk)

Outline for time-energy uncertainty section.

There are lots of refs for time-energy uncertainty. I'm planning an outline like:

• Spectral line-width - lifetime.
  • motivate with primary application.
• Time in quantum mechanics.
  • Hilgevoord: "Time in quantum mechanics: a story of confusion"; Busch: three kinds of time.
• Derived relationships
  • Mandelstam-Tamm (based on Sen); Hilgevoord
• Hilgevoord/Busch "Quantum Clock"
  • Visually interesting example illustrating some more depth in the problem.
• Quantum field theory
  • virtual particles

Johnjbarton (talk) 16:58, 22 January 2024 (UTC)

I did not get to the quantum clock. I think the line-width/lifetime section needs more work: this is the biggest application of uncertainty principle. But I need to work on another project for a while. Johnjbarton (talk) 16:55, 28 January 2024 (UTC)

Proposal to merge Stronger uncertainty relations into this article.

The section of "The Maccone–Pati uncertainty relations" in this article contains almost all of the content of Stronger uncertainty relations; we don't need the latter other than a redirect. Johnjbarton (talk) 19:32, 25 January 2024 (UTC)

EPR section

I think the current EPR section is a missed opportunity. It does not forcefully show that Einstein intended to defeat the uncertainty principle, only to be turned back at the gate by Bell so to speak. Instead the section gets too deep into what Bell is about (hopeless in this space) and misses the connection IMO.

Also the section starts with "Bohr was compelled to modify ..." which I find dubious. I did not have the impression that Bohr believed interaction caused uncertainty, that was Heisenberg's view. Bohr did not believe in position so position uncertainty was not important to him. Needs to be verified and there are lots of refs for this. @ReyHahn WDYT? Johnjbarton (talk) 17:08, 28 January 2024 (UTC)

Why do we even need an EPR discussion here? Can we just remove it?--ReyHahn (talk) 17:17, 28 January 2024 (UTC)

Based on this bit of Einstein–Podolsky–Rosen paradox local hidden variables would violate uncertainty:

• As Manjit Kumar writes, "EPR argued that they had proved that ... [particle] B can have simultaneously exact values of position and momentum. ... Particle B has a position that is real and a momentum that is real. EPR appeared to have contrived a means to establish the exact values of either the momentum or the position of B due to measurements made on particle A, without the slightest possibility of particle B being physically disturbed."

Johnjbarton (talk) 18:10, 28 January 2024 (UTC)

Thanks. I just removed all the nonsensical text. That was very weirdly worded. Be free to add something about Bohr or expand on Bell if you find it relevant to the uncertainty principle.--ReyHahn (talk) 11:10, 29 January 2024 (UTC)

Minor format comments

Since some were requested, below are some. As a general comment, like many "big" pages things seem to have been tacked on, and some merging/rationalization is possible.

• Why a box around the first equation?
• The dreaded paragraphs without refs.
• Parts read like a textbook, with (for example t) "We are interested.."
• The figure in harmonic oscillator with Gaussian initial overlaps the equations on my android tab.
• m for mass (true or effective?) is not defined.
• Add a energy-loss Figure (exciton?) for the energy/time?
• The density matrix is used but not defined.
• Entropic uncertainty of the normal distribution - wrong font size. Also some headings below that as well.
• Harmonic analysis seems to duplicate earlier Fourier transform.
• Why is DFT there? Digression?
• Relevance of Hardy's?
• Applications section seems irrelevant.

Ldm1954 (talk) 22:47, 7 February 2024 (UTC)

I agree that these are issues which should be cleaned up for this important topic.

Maybe the harmonic analysis can be moved to Harmonic analysis? Or to the Fourier transform section on uncertainty? Overall this section is too long for this article. (including Hardy, DFT).

I've suggested above that the proof be omitted. It's not a special proof and to me it distorts the physics. The uncertainty is a consequence of a physical model, not a math fact as "proof" would imply.

Perhaps the applications section references can be repurposed; I agree these are not applications. The key application the lifetime - stability relation. Johnjbarton (talk) 23:11, 7 February 2024 (UTC)

Go for it.. Ldm1954 (talk) 23:36, 7 February 2024 (UTC)