Regarding the observer effect.

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In summary, the excerpt from Wikipedia about the "observer effect" in quantum mechanics is often misunderstood by laypeople. However, quantum physicists argue that the concept of "observation" and "measurement" must be defined in quantum terms to fully understand the phenomenon. While there is a change in the system due to measurement, it is not necessarily the same as the classical observer effect. The term "observer effect" is not commonly used in academic sources and is more of a philosophical concept.
  • #1
vegetto34
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I got a question. Is this excerpt from wikipedia correct?

http://en.wikipedia.org/wiki/Observer_effect_(physics [Broken])

A common layman misuse of the term refers to quantum mechanics, where, if the outcome of an event has not been observed, it exists in a state of 'superposition', which is akin to being in all possible states at once. In the famous thought experiment known as Schrödinger's cat the cat is supposedly neither alive nor dead until observed. However, most quantum physicists, in resolving Schrödinger's seeming paradox, now understand that the acts of 'observation' and 'measurement' must also be defined in quantum terms before the question makes sense. From this point of view, there is no 'observer effect', only one vastly entangled quantum system.

Does that mean there is no observer effect when acts of observation and measurement are defined in quantum terms?

Does anyone have sources that augment or dispute this excerpt?

Thanks.
 
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  • #2
A measurement is an interaction between the system and its environment (which includes the measurement device), so the state of the system can obviously be changed by the measurement.

So this "observer effect" (as defined by the article) is clearly present in QM, but no one uses that term. I don't remember seeing it in any of the QM books I've read.

It's true that the measurement device obeys the rules of QM, but in realistic situations, the interactions between the device and its environment will ensure that the "pointer" (the component that indicates the result of the measurement) behaves in a way that's indistinguishable from classical behavior. In fact, if it behaved in any other way, we wouldn't consider it a measurement.
 
  • #3
I see. So the excerpt isn't necessarily wrong? In other words, is it open to interpretation.
 
  • #4
vegetto34 said:
I see. So the excerpt isn't necessarily wrong? In other words, is it open to interpretation.
The excerpt is not particularly well written and puts the emphasis on the wrong syLLAble. IMO, the paragraph on the uncertainty principle should have been first and foremost. The lay misinterpretation of the uncertainty principle is that it is the observer effect. This interpretation misses the mark in that the uncertainty principle talks about the uncertainty in a canonical pair of variables. http://en.wikipedia.org/wiki/Uncertainty_principle" [Broken] says it much better (emphasis mine):
That is, the more precisely one property is known, the less precisely the other can be known. This is not a statement about the limitations of a researcher's ability to measure particular quantities of a system, it is a statement about the nature of the system itself as described by the equations of quantum mechanics.
 
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  • #5
Does that mean the term, the observer effect is used? I understand that the phenomena exists, but I haven't seen many academic sources using the term. However I've heard the term used in journals outside QM, though.
 
  • #6
No, it it not used at all as far as I know.
Although presumably you could across is it or something similar if you were reading academic paper that deals with the "philosophy" of QM and modern physics (and I don't mean interpretations but really philosophy), but that is not really physics (or science).
 
  • #7
f95toli said:
No, it it not used at all as far as I know.
Although presumably you could across is it or something similar if you were reading academic paper that deals with the "philosophy" of QM and modern physics (and I don't mean interpretations but really philosophy), but that is not really physics (or science).

Interpretations are really philosophy. "Observer effect" isn't a technical philosophical term I've ever come across before though.

For examples of academic philosophy on QM see any of the papers on http://www.princeton.edu/~hhalvors/papers/.
 

1. What is the observer effect?

The observer effect, also known as the Hawthorne effect, is the phenomenon in which the behavior of study subjects is altered simply due to the awareness of being observed.

2. What are some examples of the observer effect?

Some examples of the observer effect include participants in a study changing their behavior to please the researchers, employees working harder when they know their supervisors are watching, and students performing better when they know they are being observed.

3. How does the observer effect affect scientific research?

The observer effect can impact the results of a study, as the behavior of study subjects may not be a true reflection of their normal behavior. This can lead to biased or inaccurate conclusions. Researchers must take steps to minimize the observer effect, such as using covert observation or double-blind studies.

4. Can the observer effect be completely eliminated?

No, the observer effect cannot be completely eliminated, but it can be minimized through careful study design and data collection methods. Researchers can also use statistical techniques to account for any potential bias caused by the observer effect.

5. Is the observer effect always negative?

Not necessarily. In some cases, the observer effect can actually be beneficial, as it can motivate study subjects to perform better or be more compliant. However, it is important for researchers to be aware of and account for the potential effects of observation on their study results.

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