This line of argument brings us to an interesting notion: that of the interaction boundary. Let us assume an observer and a system to be observed-any observer and any system.
Between them, imagine a boundary, and call it an interaction boundary. This boundary is strictly mathematical; it has no necessary physical reality. In order for the observers to learn about the system, they must cause at least one quantum of "information" energy, momentum, spin, or what-have-you to pass from themselves through the boundary. The quantum of information is absorbed by the system or it might be reflected back and the system is thereby perturbed.
Because it has undergone a perturbation, it causes another quantum of information to pass back through the boundary to the observer. The "observation" is the observer's subjective response to receiving this information. In a simple diagram, the situation looks like this:.
In this scheme, no observation can be made without first perturbing the system. The observation is never one of the system "at rest," but of the system perturbed. If I is the information selected by the observer to send across the interaction boundary, then it is apparent that must be a function of I: i. Thus, the observation is affected by choices made by the observer, as quantum mechanics seems to teach.
In the case of atomic and some molecular phenomena, the inequality. Because all information is exchanged in quanta modern physics does not allow for the "smooth exchange" of arbitrarily small pieces of information , this situation necessarily gives rise to an inescapable uncertainty in such observations. The quantum theory takes this uncertainty into account as the Heisenberg Uncertainty Principle.
Uncertainty is not strictly a law of Nature, but is a result of natural laws that reveal a kind of granularity at certain levels of existence. Observers in modern physics truly become participants in their observation, whatever that observation might be. Calculating the Energy from Sunlight over a 12 hour period.
Such future technology may, for example, open the way to the development of new computers whose capacity will vastly exceed that of today's most advanced machines. This research was funded in part by the Minerva Foundation, Munich, Germany. The Weizmann Institute of Science, in Rehovot, Israel, is one of the world's foremost centers of scientific research and graduate study.
Its 2, scientists, students, technicians, and engineers pursue basic research in the quest for knowledge and the enhancement of the human condition. New ways of fighting disease and hunger, protecting the environment, and harnessing alternative sources of energy are high priorities. Story Source:. Materials provided by Weizmann Institute Of Science. Note: Content may be edited for style and length. Science News. Tomorrow's Technology The experiment's finding that observation tends to kill interference may be used in tomorrow's technology to ensure the secrecy of information transfer.
ScienceDaily, 27 February Weizmann Institute Of Science. Retrieved November 8, from www. Atomic Vacancy as Quantum Bit Mar.
If we could predict exactly when these events will happen, it would not be quantum mechanics. The Heisenberg "Cut" or "Schnitt" Werner Heisenberg described the collapse of the wave function as requiring a "cut" Schnitt in German somewhere along the transition from the microscopic quantum system through the "classical" apparatus to the observer and the observer's " knowledge " about the quantum system. He asked, "Where is the cut to be between the description by the wave function and the classical description?
Like Niels Bohr , his goal was to describe quantum mechanical observations in the normal everyday language about a classically understandable measuring system. For Heisenberg, an observing system could be the human eye or a familiar photograph, because for the Bohr-Heisenberg " Copenhagen Interpretation " the final aim of physics is to describe experiments and their results like we describe the things and events in everyday life, i.
The "cut" is frequently conflated with the " quantum to classical transition , the point at which the "classical" laws of physics, for example Newton's laws of motion, emerge from the quantum world. There has been a lot of controversy and confusion about the location of this cut. Is the cat simultaneously in a "superposition" of dead and alive just before the observer learns which is the case?
The simple answer is that live and dead are "possibilities," with calculable probabilities. John von Neumann contributed a lot to this confusion in his discussion of subjective perceptions and "psycho-physical parallelism," which was encouraged by Neils Bohr.
Bohr interpreted his "complementarity principle" as explaining the difference between subjectivity and objectivity as well as several other dualisms. Let us now compare these circumstances with those which actually exist in nature or in its observation. First, it is inherently entirely correct that the measurement or the related process of the subjective perception is a new entity relative to the physical environment and is not reducible to the latter.
Indeed, subjective perception leads us into the intellectual inner life of the individual, which is extra-observational by its very nature since it must be taken for granted by any conceivable observation or experiment. Nevertheless, it is a fundamental requirement of the scientific viewpoint -- the so-called principle of the psycho-physical parallelism -- that it must be possible so to describe the extra-physical process of the subjective perception as if it were in reality in the physical world -- i.
Of course, in this correlating procedure there arises the frequent necessity of localizing some of these processes at points which lie within the portion of space occupied by our own bodies. But this does not alter the fact of their belonging to the "world about us," the objective environment referred to above.
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What is an observer in quantum mechanics? Ask Question. Asked 10 years, 6 months ago. Active 1 year, 5 months ago. Viewed 15k times. Improve this question. Isaac Isaac 2, 3 3 gold badges 23 23 silver badges 35 35 bronze badges. I presume you mean quantum theory?
Not that a classical observer is easy to get really straight. My immediate reaction is that you should go to the Stanford Encyclopedia of Philosophy, plato. I know the subject is sensitive. My question accepts the answer "nobody knows". But I personnally do not guess so; otherwise, how could experiments be done? How could theory be so precise? No matters which interpretation is the correct one, I suppose it can be given at least a few hints. It's more correct to say that we do know that there is no unique answer because the question depends on definition and is associated with no operational way to test it.
We talk about observers to express the idea that various properties of physical systems may be "perceived" or measured by some objects, but what is exactly needed for an object to be able to measure "something" with a certain "accuracy" depends on the "something" and the "accuracy", as well as all other details. There is no "universal" answer to all such questions.
For more recent discussion and more references it is possible to see, eg: M. Schlosshauer, Decoherence, the measurement problem, and interpretations of quantum mechanics, Rev. Show 1 more comment. Active Oldest Votes. Improve this answer. Anonymous Coward Anonymous Coward 1, 9 9 silver badges 8 8 bronze badges. The main point would be that "observer" is not a precisely defined concept; there isn't any set of mathematical conditions that something has to be considered an observer, for example.
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