Reddit mentions of Quantum Processes Systems, and Information

Here go some resources I like (I might update this list). LdR

Books:

• Nielsen & Chuang
  
  
• Jeffrey Bub, Banana World: quantum mechanics for primates
  
  
• Schumacher & Westmoreland
  
  Online lecture notes:
  
  
• John Preskill
  
  Video series of lectures:
  
  
• Rob Spekkens, check out also other lecture series at PIRSA.

There are so many misconceptions about this, including in the responses here! Before explaining, I need to provide an important disclaimer about this question.

"What is observing?" is not a strictly scientific question. Other examples of this type of question are the philosophical discussion of material substance, or the philosophical discussion of whether or not scientific empiricism is "true". All of these questions are asking about how to interpret a scientific result. This means that that the answer is at least partially a philosophical one and as a consequence is, at least partially, unproveable. But that doesn't mean we can't distinguish between good and bad interpretations! Typically we argue that a good interpretation is one that satisfies Occam's Razor. One that doesn't inherently hold contradictions, and one that is simple compared to others.

Now that we know the stakes, let me try to explain the results, and how I've come to interpret them. I think the proper way to address the issue is to begin by explaining some poor choices of vernacular behind this section of physics.

For starters, quantum mechanics and classical mechanics are not competing descriptions of the universe, they are simply poorly named categorizations. Better names would be classical phenomena and quantum phenomena; this frames their competitiveness (or lack-there-of) more appropriately.

Second, observation is not terribly important, and a much better phrase for understanding the quantum phenomenon of probabilistic states is with the phrase information isolation. A great textbook that takes this perspective and is a very enlightening read is Benjamin Schumacher's Quantum Processes Systems, and Information.

Ok, we get it it, so what's this other interpretation?

Information isolation is a property that a system can have. An excellent example of this is the Schrodinger's Cat experiment. The system (decaying atom, poison, cat, scientist) is constructed in such a way that the scientist is informationally isolated from the other components in the system. Until the scientist interacts with the other components of the system and BREAKS this information isolation -- which may or may not result in their reading/interpretting the results, the state inside the box is unknown.

Let's be clear then: state collapse is not a universal event, it is an event relative to the informationally isolated component (scientist in this case) from the other informationally-correlated components (decaying atom, poison, cat). This particular collapse occurs when the scientist's observable universe contains the information required to deduce what happened inside the box. What happened inside the box is still a fixed thing, regardless of when that information isolation is broken, at least as far as the informationally-correlated components are concerned.

Many of you might be asking, "NuneShelping, this doesn't seem weird at all, it just seems obvious." and you're right, it is. Don't give in to the hype/mysticism that ignorance has created in this subject. Also, read the book I suggested, it's good.

Quantum

Easy: Zettili, Comprehensive reference: Cohen-Tannoudji

or if you want more foundational books

Easy: Schumacher and Westmoreland, Comprehensive: Ballentine

These videos are incredible.

Extremely clear undergraduate quantum text which emphasis on quantum information.

With a little google-fu you can find the book in pdf format.