Entries by Arnold Neumaier

The 7 Basic Rules of Quantum Mechanics

For reference purposes and to help focus discussions on Physics Forums in interpretation questions on the real issues, there is a need for fixing the common ground. There is no consensus about the interpretation of quantum mechanics, and – not surprisingly – there is disagreement even among the mentors and science advisors here on Physics…

Clarifying Common Issues with Indistinguishable Particles

Commonly there is a lot of imprecision in talking about ”indistinguishable” (or ”identical”) particles, even in serious work. This Insight article clarifies the issues involved in a conceptually precise way. Classical mechanics. Historically, indistinguishable particles were introduced in order to explain the failure of the thermodynamics of a Newtonian ##N##-particle system to describe the absence…

A Classical View of the Qubit

This Insight article is part of my paper Foundations of quantum physics III. Measurement, featuring the thermal interpretation of quantum physics. See this discussion. $$\def\D{\displaystyle} % display style \def\SS {{\bf S}} \def\Bsymbol#1{{\bm #1}} \def\Bsigma{{\sigma}} \def\half{\frac{1}{2}} \def\<{\langle} % expectation \def\>{\rangle} % expectation \def\fct#1{\mathop{\rm #1}} % e.g., \fct{tr} \def\fns#1{{\mbox{\rm \scriptsize#1}}} % subscript text \def\Tr{{\fct{Tr}}}$$ Stokes’ quantum counter. One…

Vacuum Fluctuations in Experimental Practice

This Insight Article is a sequel of the Insight Articles ”The Physics of Virtual Particles”, “Misconceptions about Virtual Particles“ , and ”The Vacuum Fluctuation Myth”, which make precise what a virtual particle is, what being real means, document some of the liberties taken in physics textbooks in the use of this concept, mention the most…

The Vacuum Fluctuation Myth

This Insight Article is a sequel of the Insight Articles ”The Physics of Virtual Particles” and “Misconceptions about Virtual Particles“ which make precise what a virtual particle is and what being real means, document some of the liberties taken in physics textbooks in the use of this concept, and mention the most prominent misuses. A further…

Misconceptions about Virtual Particles

This Insight Article is a sequel of the Insight Article ”The Physics of Virtual Particles”, which contains an exposition of definitions that are physically justified, and in particular makes precise what a virtual particle is and what being real means. As discussed in detail in the companion article, virtual particles are defined as (intuitive imagery for)…

The Physics of Virtual Particles

In discussions on the internet (including a number of wikipedia pages) and in books and articles for non-experts in particle physics, there is considerable confusion about various notions around the concept of particles of subatomic size, and in particular about the notion of a virtual particle. This is partly due to misunderstandings in the terminology used,…

Causal Perturbation Theory

Relativistic quantum field theory is notorious for the occurrence of divergent expressions that must be renormalized by recipes that on first sight sound very arbitrary and counter intuitive. But it doesn’t have to be this way…. The basic building blocks of any quantum field theories are free fields that serve to define irreducible representations of the Poincare group with…