Is the quantum measurement problem a question?

The problem of quantum measurement is an unavoidable problem in the development of quantum mechanics. It involves the essence of quantum mechanics, and related disputes have existed to this day. Physicists have different views. The author N. D. Mermin believes that there is no measurement problem in quantum mechanics: the physical system does not have a "real" quantum state, and the state depends on the choice and calculation of physicists. Of course, for many physicists, the attitude towards the interpretation of quantum mechanics is "Shut Up and Calculating!" Interestingly, this famous saying that was always An of Ferman was actually the earliest in writing in writing N. D. Mermin's pen. Essence

Written article | N. D. Mermin (Professor Rongxiu, Department of Physics at Cornell University)

Translation | 1/137

The collapse of the wave function is a view of a physical process from misunderstanding of probability and its role in quantum mechanics.

--author

Quantum physicists are divided into three types: (1) believe that quantum mechanics is destroyed by the so -called measurement problem; (2) Like me, there is no measurement problem; (3) believe that this problem is not worth serious consideration. You can find the first two categories of 17 physicists and philosophers in Chapter 7 of Maximilian Schlosshauer's "Elegance and Enigma" in Chapter 7 of Maximilian Schlosshauer. Essence

Most of these three categories will agree with the following points: quantum mechanics can completely describe the physical system with the help of quantum state; state is the program for all possible answers to all possible questions in the system; It is statistics; no deeper theory can give a more comprehensive description.

The state of giving a system can change over time through two ways. If no measurement is made for a system [1], its attitude will evolve with certainty: continuously and in accordance with the given rules. If a question is raised on the system -called a measurement -then when the system responds, this state will become a certain state discontinuously, which depends on both the state and the system. Specific answer to measurement. The second process is called collapse of the state. (State) collapse is usually sudden, discontinuous and random.

One physical system and another physical system that performs a specific measurement -one measurement device (Appaatus) -the quantum mechanics can be treated as a single composite system. If it does not measure it, then the time evolution of the definitation of the system is given to the system of the system. However, if it is measured by the entire composite system, the attitude of the composite system determines the probability; this probability will give the possible answers to the original system's attitude and the state of the measurement device that indicates these possible answers. These correlation probability is the probability of quantum mechanics to the original separate system. Therefore, as far as probability is concerned, there is no difference in using quantum mechanics for the original system, or the composite system of the original system+(measurement) device.

Many physicists in class (2) will add that there is no consequences except that all probability is generated, and there is no consequences of quantum state distribution. Although many (perhaps most) physicists regard the probability of probability as the objective characteristics of the world, most probability scholars or statisticians do not think so. As the famous probability scientist Bruno de Finetti said in 1931, "abandoning the fuel (Phlogiston), the cosmic ether, absolute space and time ... or the existence of fairy and witch existence The concept of superstition is an important step on the road of scientific thinking. The probability is also the same. If it is regarded as a certain objective thing, then this is also a misleading fallacy. The illusion of belt visualization or materialize.

Those physicists who have the probability and belief must also be materialized, and the latter is just a catalog of this information. However, a physicist who regards probability as a personal judgment will inevitably regard the quantum state he or she assigned as a directory for his own judgment. At the turn of this century, Carlton Caves, Christopher Fuchs, and Rudiger Schack emphasized that the system of the system only expresses the belief of a specific physicist who gives the system to the system. This is a quantum. The key to the interpretation of mechanics.

Quantum measurement problem

The measurement problem comes from the two different ways to review and measure: the system itself, or the system+measurement device. If the system itself is measured, its attitude will collapse. However, if the measurement device is not checked, the composite system+measurement device does not collapse. Which description is correct? Which is a real state?

The answer given by the physicists in the (2) class is that the physical system does not have a real state. What people choose to use as a physical system and what attitude is assigned to it depends on the judgment of a specific physicist who measures the system. They use the probability of calculating the answer to the quantum mechanics.

The interaction between this continuous and random time evolution is also a characteristic of the usual classic probability. When the statisticians give the probability to the answer to system questions, the laws of these probability change over time are given by an isolated and unlocked system evolved. But these probability also depends on the further information of the system obtained by statistics from any other source. Probability update is a mutation and discontinuous part in the classic process. No one has never worried about classic measurement problems. If all the content of quantum state is the directory of the probability it produces, then every physicist who uses quantum mechanics plays the role of statisticians. A physicist obtains further information -whether it is to read the display of the measurement instrument, through the communication with other physicists, or just reinterpreting the knowledge he has mastered — it can lead to these probability of these probabilitys. Suddenly changed, and it was updated (the physicist) to show their quantum state. There is no quantum measurement problem.

The first type of physicists use different methods to deal with their measurement problems:

In all aspects of them, in their superior quantum mechanics, Landau and Lifshitz insisted that quantum mechanics should not be regarded as a tool in the concept of observers. This has led them to the interaction between quantum and classic objects. How to distinguish these two types -they have never explained -it is the measurement of their (not explained).

Other people can eliminate the existence of observer by introducing a special physical noise. This noise only interacts with a subsystem that contains a macro -liberal degree. This special noise is designed to provide a physical mechanism for the objective collapse of objective state. They solve the measurement problem by introducing a new physical process.

There are others who have completely eliminated the collapse to remove the personal judgment of each physicist. They use a quantum state to describe an incredible continuous fork (that is, multi -world explanation [2]), which contains all possible results that may be measured.

These solutions believe that quantum state is the objective attribute of the physical system they described, rather than the directory of personal judgment made by individual user users of each quantum.

Make scientists "in this mountain" [3]

Why do we have to objectively understand the laws of science? Science is a kind of human activity, and its laws are expressed in human language. As an empiricist, most scientists believe that their understanding of the world is based on their personal experience. Why insist on my explanation of science -I use to understand the world I experience (?) — Should never mention myself? The existence of the "quantum measurement problem" either has not been solved or there are many incompatible solutions, which effectively proves that scientists' experience does play an important role in understanding the theory of quantum theory, just as statistical experience is usually understanding. The probability theory plays an important role.

Many physicists have refuted this view. They believe that long before physicists, quantum state has collapsed in the early universe. I want to know if they also believe that before the statistical scholars have been updated in the early universe.

Niels Bohr has never mentioned quantum measurement. In the end, I used a statement to make a summary. This sentence simply expressed the above point of view, that is, there is no such (quantum measurement) problem. The collective is understanding as an individual of each of us: "The purpose of our description of nature is not to reveal the true essence of the phenomenon, but to track the relationship between all aspects of our experience as much as possible." I believe that this has not been confirmed that this has not been confirmed The vagueness of the first -person plural is still the cause of many misunderstandings that still bother to interpret the problem of quantum mechanics.

Further information

1. M. Schlosshauer, Ed., Elegar and Enigma: The Quantum Interviews, Springer, 2011, Chap. 7. 7.

2. B. DE Finetti, Theory of Probability, Interscience, 1990, Preface.

3. C. A. Fuchs and R. Schack, Quantum-Bayesian Coherence, Reviews of Modern Physics 85, 1693 (2013).

4. N. D. Mermin, Making Better Sense of Quantum Mechanics, Reports on Progress in Physics, 82, 012002 (2019).

5. N. Bohr, Atomic Theory and the Description of Nature, Cambridge U. Press, 1934, P. 18. Notes

[1] The original text was "if no question is asked of a system".

[2] MANY-WORLDS International.

[3] The original text was Keep the Scientist in the Science.

This article is authorized by the author N. D. Mermin Published in "Return", translated from ARXIV: 2206.10741, the original title a Note on the Quantum Measurement Problem; 6, 62 (2022); https://doi.org/10.1063/pt.3.5027.

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