[Entangled Photon Polarization Qubits]In her YouTube video Bell's Theorem Experiments on Entangled Photons, Dr. Fugate shows how polarization-entangled photons violate Bell's inequality. In
Towards the end of the first lecture for the Qiskit Global Summer School 2025, Foundations of Quantum Mechanics, Olivia Lanes (Global Lead, Content and
Comment on PBS Space Time video
PBS Space Time produces some very good videos on the foundations of quantum mechanics (QM), so let me comment on their
[Schrodinger's cat]The concept of quantum superposition (or superposition for short) is very counterintuitive, as Schr##\ddot{\text{o}}##dinger noted in 1935 writing [1],
In Chapter 37 of "The Feynman Lectures on Physics Volume 1," Richard Feynman famously wrote that the mystery of wave-particle duality in the double-slit
Overview
This article provides an accessible introduction to quantum computing, a cutting-edge technology that processes certain types of information
[mermin device quantum entanglement]Superdeterminism as a way to resolve the mystery of quantum entanglement is generally not taken seriously in the foundations community, as explained in
This Insight article presents the main features of a conceptual foundation of quantum physics with the same characteristic features as classical physics
This Insight is a condensed version of No Preferred Reference Frame at the Foundation of Quantum Mechanics. Reference numbers here correspond to that paper.
[quantum double slit experiment]What Does the Double-Slit Experiment Prove About Quantum Reality?The double-slit experiment demonstrates that light and matter exhibit both wave and
Introduction
In this article, we take as our starting point the original equations which Compton drew up and solved in his ground-breaking 1925 article: From
Introduction
In a previous article entitled "Alternate Approach to 2D Collisions" we analyzed collisions between a moving and stationary object by defining
[hydrogen]Introduction
In previous articles relating to various transition energies in Hydrogen, Helium, and Deuterium we have employed the following formula for
Note: This Insight was previously titled, "Answering Mermin's Challenge with Wilczek's Challenge." While that version of this Insight did not involve any
In a recent thread, I outlined how to compute the correlation function for the Bell basis states\begin{equation}\begin{split}|\psi_-\rangle &=
[Deuterium Lyman Alpha Line]Introduction
In this article, we will be revisiting a somewhat understudied (and seemingly unrepeated) experiment to measure the Deuterium Lyman Alpha
Introduction
In a previous article "Calculating the Balmer Alpha Line" we mentioned how accurate predictions of the spectral lines of singly ionized Helium
Introduction
Most readers acquainted with the hydrogen spectrum will be familiar with the set of lines in the visible spectrum representing transitions
[quantum superposition]What is superposition
Superposition is a fundamental concept in physics and mathematics, particularly in the fields of wave theory and quantum mechanics.
The Classical Limit of Commutator (without fancy mathematics)
Quantum mechanics occupies a very unusual place among physical theories: It contains classical
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
[Quantum Particles]Introduction
Commonly there is a lot of imprecision in talking about ''indistinguishable'' (or ''identical'') particles, even in serious work. This Insight
This Insight article is part of my paper Foundations of quantum physics III. Measurement, featuring the thermal interpretation of quantum physics. See
Incomplete interpretations of quantum mechanics
I argue that all interpretations of quantum mechanics (QM) are incomplete, each for its own reason. I
[Quantum Eraser]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]
In this Insight, I will show how the Popescu-Rohrlich (superquantum) correlations provide an unreasonable advantage in a particular "quantum guessing game''
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
[qft_renormalization]This is one chapter in a series on Mathematical Quantum Field TheoryThe previous chapter is: 15. Interacting quantum fields.
16. Renormalization
In
This is one chapter in a series on Mathematical Quantum Field Theory.The previous chapter is 14. Free quantum fields.The next chapter is 16. Renormalization.
15.
This is one chapter in a series on Mathematical Quantum Field TheoryThe previous chapter is 13. Quantization.The next chapter is 15. Interacting
[qm_interpretations]A topic that continually comes up in discussions of quantum mechanics is the existence of many different interpretations. Not only are there different
The following is one chapter in a series on Mathematical Quantum Field Theory.The previous chapter is 12. Gauge fixing.The next chapter is 14.
The following is one chapter in a series of Mathematical Quantum Field Theory.The previous chapter is 11. Reduced phase space.The next chapter
[qtf_phased_space]The following is one chapter in a series on Mathematical Quantum Field Theory.The previous chapter is 10. Gauge symmetries.The next chapter is
This is one chapter in a series on Mathematical Quantum Field Theory.The previous chapter is 9. Propagators.The next chapter is 11. Reduced phase
This is one chapter in a series on Mathematical Quantum Field Theory.The previous chapter is 8. Phase space.The next chapter is 10. Gauge symmetries.
9.
[qtf_phasespace]The following is one chapter of a series on Mathematical Quantum Field Theory.The previous chapter is 7. Observables.The next chapter is 9. Propagators.
8.
The following is one chapter in a series on Mathematical Quantum Field Theory.The previous chapter is 6. Symmetries.The next chapter is 8. Phase
The following is one chapter in a series on Mathematical Quantum Field Theory.The previous chapter is 5. Lagrangians.The next chapter is 7. Observables.
6.
[qft_lang]This is one chapter in a series on Mathematical Quantum Field Theory.The previous chapter is 4. Field Variations.The next chapter is 6. Symmetries.
5.
This is chapter 4 of a series on Mathematical Quantum Field Theory.The previous chapter is 3. Fields.The next chapter is 5. Lagrangians.
4.
The following is one chapter in a series on Mathematical Quantum Field TheoryThe previous chapter is 2. Spacetime.The next chapter is 4. Field
[qft_spacetime]The following is one chapter in a series on Mathematical Quantum Field Theory.The previous chapter is 1. Geometry.The next chapter is 3. Fields
2.
These notes mean to give an expository but rigorous introduction to the basic concepts of relativistic perturbative quantum field theories, specifically
This is the beginning of a series that gives an introduction to perturbative quantum field theory (pQFT) on Lorentzian spacetime backgrounds in its
[quantumpeace]Why I'm a Bohmian and Questioning Orthodox QM
Many people here know that I am a "Bohmian", i.e. an adherent of a very non-orthodox interpretation of quantum
Part 1: Quantum Mechanics[This article expects the reader to have some experience with quantum field theory and path integrals][I should also
Quantum Mechanics(QM) is one of the greatest intellectual achievements in human history. Not only because it describes the world at the microscopic level
[quantumflux]Introduction and context
This Insight Article is a sequel of the Insight Articles The Physics of Virtual Particles, Misconceptions about Virtual
This is a little note about quantum amplitudes. Even though quantum probabilities seem very mysterious, with weird interference effects and seemingly nonlocal
This Insight Article is a sequel of the Insight Articles The Physics of Virtual Particles and Misconceptions about Virtual Particleswhich
[anyon]Every quantum physicist knows that all particles are either bosons or fermions. And the standard textbook argues that this so does not depend on the number
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,
Introduction
Many times, we encounter ourselves tangled in some Quantum Mechanics (QM) interpretations debates. Unfortunately, the standard of discussion
[spacetime6] Last time I sketched how physicists use quantum electrodynamics, or 'QED', to compute answers to physics problems as power series in the
Quantum field theory is the best method we have for describing particles and forces in a way that takes both quantum mechanics
In this series, we're looking at mathematical problems that arise in physics due to treating spacetime as a continuum---basically, problems
[electronatom]Atoms are stable because electrons do not behave as classical orbiting particles. Quantum mechanics describes electrons using wavefunctions and stationary
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
After having constructedgauge fields and higher gauge fields in the previous articleby systems of##L_\infty##-algebroid-valued
[uncertaintyenergy]Direct answer: No, the Heisenberg time-energy uncertainty relation does not violate conservation of energy in quantum mechanics. The relation describes
After having recalled ordinary gauge fields from a dg-algebraic perspective in the previousarticle, here I discuss
After having motivated the need for prequantum field theory and having laid out its principles (i.extremal action, ii.global
[planck]The Planck length is an extremely small distance constructed from physical constants. Many misconceptions overstate its physical significance, claiming
Last time we saw that nobody yet knows if Newtonian gravity, applied to point particles, truly succeeds in predicting the future. To be precise:
Einstein's Photoelectric Insight
One of the most spectacular theoretical descriptions that Einstein had ever produced is the corpuscular nature of light
[hupmisconceptions1]One of the common misconceptions about the Heisenberg Uncertainty Principle (HUP) is that it is the fault of our measurement accuracy.A description
Can You Quantum Tunnel Through a Wall?
Short answer
The short and sweet answer if a tennis ball, a bowling ball, or any other kind of ordinary macroscopic
What is Quantum Entanglement?
Though any pair of particles, given their history, might happen to be entangled, some pairs are more entangled than others.
[qftintegrals]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.
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
Relativistic quantum field theory is notorious for the occurrence of divergent expressions that must be renormalized by recipes that on first sight sound
[cheshirecat]In a previous Insight, Weak Values Part 1: "Asking Photons Where They Have Been," I showed different methods for computing the relative intensities in
May 30, 2015
In a previous Insight on retrocausality, I explained an experiment by Danan, Farfurnik, Bar-Ad, and Vaidman (DFBV)[1], Asking Photons Where They Have
Introduction
This is a follow on from my paper explaining renormalization. A question was raised - why exactly do we need a cut-off. There is a deep reason
[renormalization]What Is The Issue With Renormalisation
If you have an interest in physics you have likely come across renormalisation before, although what it really
May 9, 2015
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 presented
May 9, 2015
In 1981, Mermin published a paper[1], "Bringing home the atomic world: Quantum mysteries for anybody" in which heexplained the mystery of quantum nonlocality[2]
[2D Animation]Introduction
The particle in a box is a staple of entry-level quantum mechanics courses because it provides a clear contrast between classical and quantum