How does a human being become an observer in quantum theory - by Viktor T. Toth - Quora Question Review

This document contains a review of the answer by Viktor T. Toth on the question in Quora: "How does a human being become an observer in quantum theory"
To order to read all the answers select: https://www.quora.com/How-does-a-human-being-become-an-observer-in-quantum-theory

• The text in italics is copied from the article.
  
• Immediate followed by some comments
  

Contents

• 1. Answer Review

  Reflection

  • Reflection 1 - Question Review
  • Reflection 2 - Classical System versus Quantum System

  ---

  1. Answer Review

  The "observer" business is one of the most painfully misunderstood aspect of the quantum theory and its various "interpretations".

  So allow me to make a point rather forcefully: The "observer" or "instrument" has absolutely nothing, zero whatsoever, to do with human beings, cats, consciousness, or any similar fanciful notions.

  No, it is about a quantum system interacting with a system is classical (as in nonquantum) or at least close enough to classical so that it makes no practical difference.

  Select: Reflection 2 - Classical System versus Quantum System

  How, you wonder? Well... A quantum system is described in the form of states. (That's what the infamous wavefunction represents: a combination of possibly an infinite number of states.) A quantum system is "quantum" because usually, it is in a "linear combination" of states, that is, a whole bunch of states with different weights ("amplitudes") attached to them.

  The physical reality does not include any form of mathematics.

  To the extent that this can be interpreted in a manner that appeals to our intuition (though I'd advise against it - intuition can really mislead you here) it literally means that the quantum system is in many states at once.

  What does it mean that an electron, or photon is in many state at once?
  What you could do, is to declare that each electron or photon is in a different state

  But a classical system cannot be in many states at once. In classical physics, the state of a system is unambiguous.

  To declare that the state is unambiguous, implying always not-well-defined, has no meaning.

  A classical particle always has a well-defined position and a well-defined velocity.

  The thermonology classical particle is misleading. See Reflection 2 - Classical System versus Quantum System
  It is important to make a clear difference between a classical particle and a quantum particle, if such a difference exists. From a physical point it does not.

  So here is what happens when a quantum system interacts with a classical system: For that interaction, the quantum system itself is forced to be in a well-defined, unique state with respect to whatever characteristic of the quantum system (usually its position or its momentum) interacts with the classical system.
  As a result of the interaction, the classical system's state changes, it can be read, and from this, the state of the quantum system at the moment of the interaction can be inferred. So a property of the quantum system is "measured".

  The idea that a quantum system interacts with a classical system and vice versa is misleading.
  See also: Reflection 1 - Question Review were a "burning process" is discussed.

  This can be interpreted in a variety of ways. One possibility is that the act of measurement caused the quantum system to "collapse" from a linear combination of states to a specific state that corresponds to the measurement. This is "wavefunction collapse" and it is fraught with problems, not the least of which is that ultimately it basically means replacing the entire universe (characterized by one wavefunction) with a different universe (characterized by the other, collapsed wavefunction).

  In the "burning process" photons are observed by all observers surrounding the fire. To call that "wavefunction collapse", I don't see the advantage.

  Or, we can accept that the act of measurement "guides" the quantum system towards a specific state, even though the measurement is in the future. This sounds horribly counterintuitive and seemingly in violation of causality, but curiously, no actual causality violation takes place!
  The future may guide the quantum system this way, yet it still cannot be used to send signals back into the past.

  A human can only control, influence the future by performing certain actions at present. It is the same as what a butterfly does.

  Still, this "nonlocal" nature of this view is just too unpalatable to many, so it is often dismissed.

  Most of this text is not clear.

  In any case, none of this has anything to do with human beings. With conscious "observers". It really is, quite simply and literally, about interactions between quantum systems and classical systems. And of course in reality, classical systems don't really exist (everything consists of a finite number of quantum particles) but when the "classical" object has a very large number of "uncorrelated quantum degrees of freedom" the result is truly indistinguishable from a truly classical object. So the classical idealization is not an oversimplification insofar as practical experiments are concerned.

  This text is not clear.

  Again, no humans. No "observers". Just quantum vs. classical, interacting.

  No

  ---

  Reflection 1 - Question Review

  The question: "How does a human being become an observer in quantum theory" is in many ways not clear.
  In many experiments, like burning wood, humans are involved. People collect wood, make a pile of it and set it on fire. That means people are involved and are also the observers.
  In this case humans are not directly involved with the process i.e., the burning process. That is the case in many processes, but not always.

  However when you burn something this burning involves the emission of light i.e. photons. All the people surrounding can observe the fire and will collect photons in their eyes. Each of these instances can be called an event. At such an event the energy of the photon will be transferred into the nerve system of the observer. In that case the observer, you could call, becomes unwillingly, part of a quantum system.
  All these events will not influence the burning process
  

  ---

  Reflection 2 - Classical System versus Quantum System

  There does not something exist like a Classical system and a Quantum system; the two are intertwined, they cannot be seperated.
  A Quantum system is a collection of the elementary particles and Quantum mechanics is the science that studies the details of the behaviour of the elementary particles. But that approach is not correct.
  The universe is a collection of objects from large to small, from Blackholes to stars to planets and dust. These objects in turn can form Galaxies, star clusters, star systems like our solar system and gas clouds.
  The point is that each of these objects in fact is a collection of elementary particles including radition and photons, which can interact with each other. This interaction is the field of quantum mechanics.

  ---

  If you want to give a comment you can use the following form Comment form

  ---

  Created: 3 Oktober 2023
  
  

  Go Back to Quora Question Review
  Back to my home page Index