Talk:Observer effect

(random heading)
(inserted for readability ... said: Rursus ( m bork³ ) 15:19, 27 November 2009 (UTC))

Not sure about the parapsychology bit. The sentence was just clunky before, but now I'm not sure I matched the intent of the original poster. Does anyone have specifics on what the term really means in parapsychology? —The preceding unsigned comment was added by 69.108.101.72 (talk • contribs).
 * Undated. ... said: Rursus ( m bork³ ) 15:19, 27 November 2009 (UTC)

physics? i think not
do not confuse the observer effect with the uncertainty principle. the uncertainty principle has nothing to do with "observing", it has to do with measuring. the observer effect is a supposed effect of observing an event and the influence of your presence on the event. no one would ever have to actually observe a particle's position to obfuscate its momentum, the mere act of using the photons to measure its position, even if nobody ever observed it, would suffice.

- don't you have to observe in order to measure? -

Indeed. But what does measuring have to do with Quantum Mechanics exactly?

To measure is to observe the results of a measurement process [that ascertains the subject measurement]. Humans observe with their senses — the senses that humans have. Other conscious beings, perhaps including computers, may have other senses with which they can implement tools for making measurements. At the end of the day, measuring ALWAYS involves observing.

Tools used by beings to make measurements are limited (in their accuracy) by various factors including the limitations of ones senses. The often-mentioned example of bouncing a photon off of an atom to measure its position illustrates the problem with knowing the position AND momentum of THAT atom at the SAME MOMENT in time. The concept usually centers on the fact that the position measurement photon will change the momentum of the subject atom. But aren't there other aspects of this problem?

In the limit (considering the non-zero mass of the atom and the non-zero energy of the photon), can one ever know perfectly even the position alone? Perhaps so, since the mechanical inertance of the atom precludes its reaction at THAT infinitesimal instant in time.

Why is not THIS example an instance of "observer effect" rather than the uncertainty principle, per se? If one seeks only to measure the position alone, then maybe it is neither. Then again, is it not "Observer Effect" even if the momentum is changed by measuring only the position? One would think so.

Well, what if we start with measuring the momentum "first"? How does one measure momentum, anyway? Again, we observers devise a measurement process that allows our senses to detect the "answer." Momentum is mass times velocity. If we know the mass, we might then seek to measure the velocity. Human observers tend to ascertain velocity by measuring position at two points in time. For non-zero velocities, this means two different points in space, of course. Yet, [instantaneous] velocity is DEFINED at only one point in space and time. Thus, one cannot measure velocity (or momentum) in this manner: one must WAIT to SEE how fast it is moving, and this yields only an average (not instantaneous) value.

Before continuing on to propose measuring momentum, per se, by some other means (say, smashing the atom into an obstacle at a known position), we should note that the Uncertainty Principle pertains only to Quantum Mechanics. In THAT world, particles are not particles; rather, they are probability density functions. The interpretation of this MODEL of a particle says the position and momentum of the subject particle are INHERENTLY uncertain by virtue of the mathematical model itself. To precisely derive the position, one must manipulate the model in a manner that causes the momentum "to drop out of the formula," and vice versa.

The relationship between position and momentum described by Quantum Mechanics is somewhat like the relationship between the time domain and the frequency domain described by the Fourier Transform. One can say that there is some similarity as well between position and velocity in Classical Mechanics. In fact, the description above with knowing the velocity versus position of the atom is exactly that: Classical Mechanics.

Following this line of thinking, one (such as this user who is not fluent in the intricate semantics of Quantum Theory) might be likely to reach these conclusions:

1. Using "particulate" atoms and photons to describe the Uncertainty Principle of Quantum Mechanics is flat wrong.

'''2. One does not observe Quantum Mechanics. Rather, one uses that theory to make calculations to explain the observations of certain experiments.'''

'3. Measurements ALWAYS involve observations and therefore also ALWAYS'' involve the Observer Effect. Perhaps this IS the “Theory of the Observer Effect.”'''

4. The Uncertainty Principle of Quantum Mechanics and the Observer Effect are fundamentally unrelated. —Preceding unsigned comment added by JimRodgers (talk • contribs) 12:54, 31 July 2008 (UTC)

JimRodgers (talk) 12:55, 31 July 2008 (UTC)


 * That topic is now treated in Talk:Observer effect (physics). ... said: Rursus ( m bork³ ) 15:19, 27 November 2009 (UTC)

Can anyone expand on this fascinating quantum issue?
For some reason this article is more focused on what the observer effect is not. --Nathanael Bar-Aur L. 20:09, 10 April 2007 (UTC)

From what I understood from other sources, the observer effect is basically the collapsing of a quantum system's wavefunction that happens the moment a measurement in made upon it (by an "observer"), therefore cancelling any superposition that may have existed beforehand, and giving specific definition to the renderings. Is this correct? --Nathanael Bar-Aur L. 20:21, 10 April 2007 (UTC)

There is a collapse in many interpretations of quantum mechanics. (Not many worlds). Apart from consciousness causes collapse, most interpretations do not put special emphasis on human observers.1Z 22:07, 10 April 2007 (UTC)


 * But isn't the term "observer effect" inclusive of mechanical "observation", as seen in the double-slit experiment by the detectors? --Nathanael Bar-Aur L. 00:55, 11 April 2007 (UTC)


 * That is a confusing usage. (As a rule, if you have to put scare quotes around a word, its the wrong word...)

1Z 01:07, 11 April 2007 (UTC)

See Measurement problem 1Z 01:09, 11 April 2007 (UTC)


 * Then why does the Observer effect in physics link suggest that? --Nathanael Bar-Aur L. 01:52, 11 April 2007 (UTC)

There is no shortage of people saying that QM is about "observers".1Z 02:17, 11 April 2007 (UTC)

I agree, this article is in need of a clearer explanation or current state of theory. Just saying that the 'photon' causes 'interaction' is not really an explanation. Preroll 23:21, 12 August 2007 (UTC)

I too would like to see this section expanded, but I'm not an expert on the subject. Cazort (talk) 18:50, 17 November 2007 (UTC)


 * That topic is now treated in Talk:Observer effect (physics). ... said: Rursus ( m bork³ ) 15:19, 27 November 2009 (UTC)

please, explain who is Wheeler, I dont see references
The text is the following:

...From this point of view, there is no 'observer effect', only one vastly entangled quantum system. A significant minority still find the equations point to an observer; Wheeler, who probably worked more deeply on this subject than any physicist thus far, devised a graphic in which the universe was represented by a "U" with an eye on one end, turned around and viewing itself, to describe his understanding...

Who is Wheeler?

J.A. Wheeler??????


 * Yes. I don't know when you wrote this but (at least now) there is a link to John Archibald Wheeler in the article. Speaking of this article's references, I wish I could see more in general. 70.59.146.224 (talk) 13:18, 26 December 2007 (UTC)


 * That topic is now treated in Talk:Observer effect (physics). ... said: Rursus ( m bork³ ) 15:19, 27 November 2009 (UTC)

Use in Pseudoscience
How about a use in pseudoscience section. People interpret the meaning of the double-slit experiment to be "thoughts influence reality" like in The Secret. —Preceding unsigned comment added by 71.219.81.194 (talk) 04:31, 13 January 2008 (UTC)

Wrong template above
This page is nowadays a disambiguation page so it doesn't belong to philosophy as far as I know, the discussion should be about whether the sentences in the article correctly represents the articles pointed out by the links provided, and whether the page is easy to overview. ... said: Rursus ( m bork³ ) 15:19, 27 November 2009 (UTC)


 * Inserted a disambig project template. ... said: Rursus ( m bork³ ) 15:21, 27 November 2009 (UTC)

Observer-Expectancy Effect inconsistency
This effect is described as being the alteration of the participants behavior because of watching researchers. On the article page however this effect is described as the unconscious influence expressed by researchers on the participants. Which one is it?