Comments about "Many-body_problem" in Wikipedia

This document contains comments about the article Many-body problem in Wikipedia
In the last paragraph I explain my own opinion.



The article starts with the following sentence.
This article is about the many-body problem in quantum mechanics. For the n-body problem in classical mechanics, see n-body problem.
For large objects select:
The many-body problem is a general name for a vast category of physical problems pertaining to the properties of microscopic systems made of many interacting particles.
It is better to speak about: clusters of elementary particles.
Microscopic here implies that quantum mechanics has to be used to provide an accurate description of the system.
In general it is impossible to describe the behaviour of elementary particles accurate.
In general terms, while the underlying physical laws that govern the motion of each individual particle may (or may not) be simple, the study of the collection of particles can be extremely complex.
The physical behaviour of elementary particles is not governed by physical laws. Physical laws are descriptions of identical physical processes
In such a quantum system, the repeated interactions between particles create quantum correlations, or entanglement.
One of the most commen interactions are collisions between elementary particles. As a result different elementary particles are created. Those particles can be described as correlations.
To use the name entanglement for these correlations, implying a physical connection, is wrong.
As a consequence, the wave function of the system is a complicated object holding a large amount of information, which usually makes exact or analytical calculations impractical or even impossible.
The problem is that a wave function of a system is very difficult to calculate accurate. In general any mathematical model of a physical system is difficult to calculate.
This becomes especially clear by a comparison to classical mechanics.
For classical systems the same is true if you want to do that accurate.

5. See also

Following is a list with "Comments in Wikipedia" about related subjects

Reflection 1 N-body problem versus many-body problem.

The question is what is the difference between a simulation of a gas-cloud versus a star cluster.
The main difference is the size of the objects.

Reflection 2

Reflection 3


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Created: 8 September 2023

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