perturbation

Introduction to Perturbative Quantum Field Theory

23 Comments
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This is the beginning of a series that gives an introduction…
quantumpeace

How I Stopped Worrying and Learned to Love Orthodox Quantum Mechanics

267 Comments
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Many people here know that I am a "Bohmian", i.e. an adherent…

15 of the Best PF 2017 Eclipse Photos

68 Comments
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The 2017 August Eclipse really was something special. Fortunately…
inflation5

A Poor Man's CMB Primer. Part 5: Quantum Seeds

2 Comments
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  The CMB establishes a record of ancient acoustic…
mathoperators

How to Tell Operations, Operators, Functionals and Representations Apart

24 Comments
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All these concepts belong to the toolbox of physicists. I read…
epsresults

Results Shown at EPS Conference

5 Comments
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The EPS conference was a week ago, and many new results and future…
m-theory

Super p-Brane Theory Emerging from Super Homotopy Theory

5 Comments
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  A notorious open problem: What is the non-perturbative…
Parsevalstheorem

An Integral Result from Parseval's Theorem

4 Comments
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Introduction: In this Insight article,  Parseval's theorem…
EdmondHamilton

Assessing the Physics in Edmond Hamilton's "The Second Satellite"

2 Comments
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This article won't contain much about physics that typical readers…
entanglement_entropy2

Entanglement Entropy – Part 2: Quantum Field Theory

3 Comments
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Part 1: Quantum Mechanics [This article expects the reader…
whatisatensor

What Is a Tensor?

48 Comments
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Let me start with a counter-question. What is a number? Before…
jimbiology

Interview with Biologist Jim McNamara

16 Comments
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What got you interested in biology? I was an amateur naturalist…
dampedforces

Damped Motion in Classical and Quantum Mechanics

21 Comments
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This Insights article is about dissipative forces (friction,…
name_the_scientist

Name the Scientist

26 Comments
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Time to test your scientist photo recognition skills! As always…
pamelagay

Interview with Astronomer Pamela Gay

2 Comments
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 Please give us a bit of background into your educational and…
SpectralParadox

Exploring the Spectral Paradox

16 Comments
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In terms of wavelength, peak solar radiation occurs at about…
undergradresearch

Niches for Publishable Undergraduate Research

6 Comments
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Undergraduate interest in research is a good thing; it's even…
coldquestioning

Very Little Excuse To Ask A Question Cold

66 Comments
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We frequently get questions such as these: "What is energy?" "What…
processing

The Joy of Processing

11 Comments
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In the early days of the personal computer revolution, computers…
entanglement_entropy

Entanglement Entropy - Part 1: Quantum Mechanics

22 Comments
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Quantum Mechanics(QM) is one of the greatest intellectual achievements…
BondiKcalculus

Relativity Using the Bondi K-calculus

18 Comments
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Although Special Relativity was formulated by Einstein (1905),…
physicslab

Revamping Undergraduate Introductory Physics Laboratory

15 Comments
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This is a compilation of my blog entry on this singular "project"…
frasercain2

Q&A With Universe Today's Fraser Cain

4 Comments
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Special thanks to Universe Today founder Fraser Cain for this…
lensfocus

Lenses and Pinholes: What Does "In Focus" Mean?

11 Comments
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In introductory physics, the optics unit often teaches about…
sabine1

Interview with a Theoretical Physicist: Sabine Hossenfelder

14 Comments
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We are pleased to introduce Sabine Hossenfelder. Sabine is a…
deriitive5

The Pantheon of Derivatives - Part V

2 Comments
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  Important Theorems - biased, of course Implicit…
RelativityVariables

Relativity Variables: Velocity, Doppler-Bondi k, and Rapidity

8 Comments
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Traditional presentations of special relativity place emphasis…
deriitive4

The Pantheon of Derivatives - Part IV

5 Comments
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  Lie Derivatives A Lie derivative is in general the…
deriitive3

The Pantheon of Derivatives - Part III

3 Comments
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  Some Topology Whereas the terminology of vector…
cameralense

New High Performance Ultra-wide Angle Lenses

7 Comments
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Note, unless otherwise specified, all focal lengths are in terms…
deriitive2

The Pantheon of Derivatives - Part II

7 Comments
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  Generalizations Beyond ##\mathbb{R}## and ##\mathbb{C}## As…
deriitive

The Pantheon of Derivatives - 5 Part Series

3 Comments
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  Differentiation in a Nutshell I want to gather the…
diffractiontheory

The Diffraction Limited Spot Size with Perfect Focusing

12 Comments
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Purpose:  The purpose of this Insights article is to give…