# Quantum Mechanics Articles

Quantum mechanics is a mathematical framework for understanding physical phenomena that fail to be described sufficiently by classical physics: the work of Newton, Maxwell, and others. You might ask, ‘Why can’t we use classical methods at that point?’ We’re unable to sufficiently probe atoms and subatomic particles with classical instruments at that scale. The simplest instruments that we can use at that scale, like probing with an electron or photon, are either too energetic or don’t have the right properties to measure what we want to measure.

This doesn’t just mean that WE are unable to measure it, but that, and this is what makes QM weird, physics doesn’t allow us to learn any more about it. So instead of being able to watch particles zooming and blipping and popping about like we are able to watch a ball on a playground, we have to use statistical methods to determine where some particles might be and where it might be going. This is the very broad description of how QM works.

### A Beginner's Guide to Baryons

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Introduction At the beginning of the 20th century it was thought that all matter consisted of only three particles: the electron, the neutron and the…

### Answering Mermin's Challenge with Wilczek's Challenge

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Nearly four decades ago, Mermin revealed the conundrum of quantum entanglement for a general audience [1] using his "simple device," which I will refer…

### The Classical Limit of Quantum Mechanical Commutator

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The Classical Limit of Commutator (without fancy mathematics) Quantum mechanics occupies a very unusual place among physical theories: It contains classical…

### What is the Double Slit? A 5 Minute Introduction

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Definition/Summary The double slit is a simple configuration used to demonstrate interference effects in waves.Equations At distances that are…

### The 7 Basic Rules of Quantum Mechanics

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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…

### Clarifying Common Issues with Indistinguishable Particles

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Commonly there is a lot of imprecision in talking about ''indistinguishable'' (or ''identical'') particles, even in serious work. This Insight article…

### A Classical View of the Qubit

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This Insight article is part of my paper Foundations of quantum physics III. Measurement, featuring the thermal interpretation of quantum physics. See…

### 9 Reasons Quantum Mechanics is Incomplete

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I argue that all interpretations of quantum mechanics (QM) are incomplete, each for its own reason. I also point out that for some interpretations (those…

### Against "interpretation"

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I am against "interpretations" of Quantum Mechanics (QM) in a sense in which John Bell [1] was against measurement in QM and Travis Norsen [2] is against…

### The Quantum Mystery of Wigner's Friend

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In this Insight I will introduce the quantum mystery called Wigner's friend'' using Healey's version [1] of Frauchiger and Renner's (FR's) version [2]…

### The Unreasonable Effectiveness of the Popescu-Rohrlich Correlations

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In this Insight, I will show how the Popescu-Rohrlich (superquantum) correlations provide an unreasonable advantage in a particular "quantum guessing game''…

### Why the Quantum | A Response to Wheeler's 1986 Paper

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Wheeler's opening statement in his 1986 paper, How Come the Quantum?'' holds as true today as it did then [1] The necessity of the quantum in the construction…

### How to Better Define Information in Physics

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When I ask questions about conservation of information I frequently get the reply, “It depends on what you mean by information.”   So, I researched…

### "Classical Physics Is Wrong" Fallacy

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One of the common questions or comments we get on PF is the claim that classical physics or classical mechanics (i.e. Newton's laws, etc.) is wrong because…

### The Fundamental Difference in Interpretations of Quantum Mechanics

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A topic that continually comes up in discussions of quantum mechanics is the existence of many different interpretations. Not only are there different…

### Introduction to Perturbative Quantum Field Theory

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This is the beginning of a series that gives an introduction to perturbative quantum field theory (pQFT) on Lorentzian spacetime backgrounds in its…

### How I Stopped Worrying and Learned to Love Orthodox Quantum Mechanics

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Many people here know that I am a "Bohmian", i.e. an adherent of a very non-orthodox interpretation of quantum mechanics (QM). Indeed, in the past I have…

### Entanglement Entropy: Quantum Mechanics

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Quantum Mechanics(QM) is one of the greatest intellectual achievements in human history. Not only because it describes the world at the microscopic level…

### The Vacuum Fluctuation Myth

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This Insight Article is a sequel of the Insight Articles ”The Physics of Virtual Particles” and “Misconceptions about Virtual Particles“ which…

### Why Is Quantum Mechanics So Difficult?

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Strangely enough, QM's formalism isn't any more difficult than other areas of physics. The mathematics of the "standard" QM isn't any worse than, let's…

### Learn the Top Misconceptions about Virtual Particles

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This Insight Article is a sequel of the Insight Article ''The Physics of Virtual Particles'', which contains an exposition of definitions that are physically…

### How the EPR Paradox Fits Between Entanglement and Nonlocality

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If we violate a Bell inequality, we know we have quantum entanglement, and it used to be thought that these two notions were one-and the same.At least,…

### Tools to Enrich our Quantum Mechanics Interpretations Discourse

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IntroductionMany times, we encounter ourselves tangled into some Quantum Mechanics (QM) interpretations debates. Unfortunately, the standard…

### Examples of Prequantum Field Theories IV: Wess-Zumino-Witten-type Theories

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At the end of this page, we will have come full circle back to the first article in the series 20 years ago -- The M-Theory Conjecture.We…

### Struggles With The Continuum: Quantum Mechanics of Charged Particles

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Last time we saw that that nobody yet knows if Newtonian gravity, applied to point particles, truly succeeds in predicting the future. To…

### Misconception of the Heisenberg Uncertainty Principle

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One of the common misconception about the Heisenberg Uncertainty Principle (HUP) is that it is the fault of our measurement accuracy.A description…

### You Will Not Tunnel Through a Wall

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We periodically get questions on PF about people wanting to know of a tennis ball, a ping pong ball, a person, a cow, etc. can tunnel through a wall, or…

### Retrocausality: How Fundamental is the Arrow of Time?

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In this Insight, I'll discuss a recent experiment ([1]  [2] [3]) by some Australian physicists that has brought a thought experiment into the real world…

### Weak Values Part 2: The Quantum Cheshire Cat Experiment

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In a previous Insight, Weak Values Part 1: "Asking Photons Where They Have Been," I showed different methods for computing the relative intensities in…

### Visualizing the 2-D Particle in a Box

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Introduction The particle in a box is a staple of entry-level Quantum Mechanics classes because it provides a meaningful contrast between classical and quantum…