Physics Articles

Here contains the collection of expert physics articles that deal with physics topics. These span all skill ranges and may include astronomy and cosmology topics. Learn something new today by professionals in the fields you are interested in!

bubbles

Explosion-Generated Collapsing Vacuum Bubbles Reach 20,000 Kelvin

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In a recent paper published in Physical Review Letters (PRL), one of the top physics journals, Jérôme Duplat and Emmanuel Villermaux developed a method…
cmb

A Poor Man’s CMB Primer: Orientation of the Universe

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 This is a picture of the cosmic microwave background:Fig 1. The cosmic microwave background as seen by the European Space Agency's…
planck

What Planck Length Is and It’s Common Misconceptions

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The Planck length is an extremely small distance constructed from physical constants. There are a lot of misconceptions that generally overstate its physical…
spacetime2

Struggles With The Continuum: Quantum Mechanics of Charged Particles

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

Exploring a Paper on Scaling Laws and the Speed of Animals

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Introduction In a recent issue of the American Journal of Physics, I read an interesting paper by Nicole Meyer-Vernet and Jean-Pierre Rospars examining…
infinity_faq

Learn the Top 5 Misconceptions About Infinity

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Introduction Understanding the behavior of infinity is one of the major accomplishments of mathematics. Sadly, the infinite is often misunderstood and…
man_on_moon

The Last Man On The Moon | A Look Back at Previous Missions

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On 11th December 1972, just over 45 years ago, man set foot on the moon for the last time.The Apollo 17 mission manned by Eugene Cernan and geologist…
spacetime

Struggles With the Continuum: Is Spacetime Really a Continuum?

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 Is spacetime really a continuum?  That is, can points of spacetime really be described---at least locally---by lists of four real numbers…
photoelectric

“Violating” Einstein’s Photoelectric Effect Model

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One of the most spectacular theoretical descriptions that Einstein had ever produced is the corpuscular nature of light that he used in his 1905 photoelectric…
CosmologicalHorizons

Inflationary Misconceptions and the Basics of Cosmological Horizons

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Introduction It is a common saying that during inflation "space expanded faster than the speed of light."  This statement is meant to articulate the…
lightswitch

What Happens When You Flip the Light Switch – From Zero Seconds to 20 Years

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Introduction Few people know what happens when a customer does something like flipping a light switch. The full explanation requires descriptions of topics…
relativitytherorm

Learn the Relativistic Work-Kinetic Energy Theorem

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I was bothered for a long time by the reasons for the relativistic validity of the work-kinetic energy relation ##\Delta E=Fd##, which holds without any…
supergravity

Emergence From the Superpoint

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 In the previous article we saw that the generalization of super-Lie algebras to homotopy super-Lie n-algebras (super L-infinity algebras)…
liealgebra

Homotopy Lie-n Algebras in Supergravity

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 The previous article in this series claimed that the mathematics of the 21st century that had fallen into the 1970s in the form of string…
string theory

It Was 20 Years Ago Today — the M-theory Conjecture

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  While the world didn't end, after all, 15 years back at the turn of the millennium, in hindsight it is curious that, almost unnoticed,…
hupmisconceptions1

Learn a Misconception of the Heisenberg Uncertainty Principle

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

Plus/minus What? How to Interpret Error Bars

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People sometimes find themselves staring at a number with a ± in it when a new physics result is presented. But what does it mean? The aim of this Insight…
LCDM4

Approximate LCDM Expansion in Simplified Math (Part 4)

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  Part 4: Cosmic Recession Rates An astronomer, accompanied by his amateur relativist friend, aimed a telescope at a distant galaxy and measured…
LCDM3

The LCDM Cosmological Model in Simplified Math (Part 3)

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  Part 3: Important Cosmological Horizons and Distances A question that often comes up is: "how big is the observable universe?"The question…
lcdmjorrie

Approximate LCDM Expansion in Simplified Math (Part 2)

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  Part 2: Time and Distance In Part 1 we have seen how one of the simplest ways of expressing the fractional expansion rate of the universe,…
neutrino

Learn About Neutrino Masses and Speed

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It was hard to miss the 2011 OPERA neutrino speed measurement that indicated superluminal neutrino speeds (and turned out to be a measurement error), but…
gravity

Understanding the General Relativity View of Gravity on Earth

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Often students have difficulty reconciling the General Relativity (GR) view of gravity versus their own experience with gravity on the surface of Earth.…
cosmo

Approximate LCDM Expansion in Simplified Math

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 If we restrict ourselves to a spatially flat LCDM universe model (and ignore the early radiation energy density), the first Friedmann equation…
physics love

Should You Do Science for Love or for Money

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When I look over the most highly cited papers and my favorite accomplishments, I am struck by the fact that most of the projects were not funded by…
measuringentanglement

Can You Measure Quantum Entanglement?

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Though any pair of particles, given their history, might happen to be entangled, some pairs are more entangled than others.Since at least the 1990s,…
garrett

Garrett Lisi’s Superparticle Bet With Frank Wilczek

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There is an interesting story unfolding in particle physics. The main motivation for building the Large Hadron Collider was to search for new particles.…
qftintegrals

Some Useful Integrals In Quantum Field Theory

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In my paper on renormalisation I mentioned what most who have studied calculations in Quantum Field Theory find, it's rather complicated and mind-numbing.…
arrowoftime

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…
research work

How to Initiate Research Work As a Physics Major

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  It has been a while since the last installment of this series, so let’s recap on where you are right now. You should already…
gas compression

Reversible vs Irreversible Gas Compression and Expansion Work

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Introduction In learning Thermodynamics, one of the difficult concepts that many students struggle with is the difference between reversible and irreversible…
perbation theory

Introduction to Causal Perturbation Theory

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Relativistic quantum field theory is notorious for the occurrence of divergent expressions that must be renormalized by recipes that on first sight sound…
cheshirecat

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…
askingphotons

Weak Values Part 1: Asking Photons Where They Have Been

In a previous Insight on retrocausality, I explained an experiment by Danan, Farfurnik, Bar-Ad, and Vaidman (DFBV)[1], “Asking Photons Where They Have…
negative temperature

What are Negative Absolute Temperatures

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It's a famous result in thermodynamics that you can't reach absolute zero no matter how hard you try. Also, the definition of absolute zero makes it obvious…
What is Energy

What is Energy? A Definition and Controversy

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What is energy? For some reason, this perfectly legitimate question seems to spawn far more than its share of bad threads. So what is energy and how do…
LHC

LHC Part 3: Protons as Large as a Barn

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Introduction See also part 1 and part 2 of the series.The LHC commissioning phase is coming to and end. On Wednesday May 20th 2015, the first collisions…
earth year

How to Scientifically Measure How Many Days Are in a Year

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How many days are there in a year?Ask pretty much anyone and they will tell you 365, except for leaps years which have 366. In addition, most people…
redlights

Learn About the Greenberger-Horne-Zeilinger Experiment

In two previous Insights, I shared Mermin's explanation of the Hardy experiment[1] and the Mermin device[2]. Both of his corresponding AJP papers…
mermin

The Quantum Liar Experiment: An Instantiation of the Mermin Device

In 1981, Mermin published a paper[1], "Bringing home the atomic world: Quantum mysteries for anybody" in which he explained the mystery of quantum nonlocality[2]…
classroom

Explore Some Sins in Physics Didactics

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Introduction There are many sins in physics didactics. Usually, they occur, because teachers, professors, textbook or popular-science-book writers, etc.…

LHC Part 2: Commissioning

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Introduction Last month, I wrote a FAQ about working at the LHC, at the time the first beams were circulating in the machine after a stop of two years.…
supernova

What are the Fates of Massive Stars

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Introduction Deep in the vastness of space, beyond our solar system, stars are born in primordial nebulae, gaseous molecular clouds on the spiral arms…
hand_to_hand_combat

Learn the Physics of Hand-to-Hand Combat

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Civilizations wax and wane but principles of physics remain steadfast. The most effective techniques from martial arts are ones that effectively dole out…