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Symmetry Arguments and the Infinite Wire with a Current

May 17, 2022/0 Comments/in Physics Articles/by Orodruin

Many people reading this will be familiar with symmetry arguments related to the use of Gauss law. Finding the electric field around a spherically symmetric charge distribution or around an infinite wire carrying a charge per unit length are standard examples. This Insight explores similar arguments for the magnetic field around an infinite wire carrying…

Superdeterminism and the Mermin Device

March 20, 2022/79 Comments/in Physics Articles/by Mark Stuckey

Superdeterminism as a way to resolve the mystery of quantum entanglement is generally not taken seriously in the foundations community, as explained in this video by Sabine Hossenfelder (posted in Dec 2021). In her video, she argues that superdeterminism should be taken seriously, indeed it is what quantum mechanics (QM) is screaming for us to…

Relativity on Rotated Graph Paper (a graphical motivation)

February 16, 2022/0 Comments/in Physics Articles/by robphy

(based on https://www.physicsforums.com/threads/teaching-sr-without-simultaneity.1011051/post-6588952 and https://physics.stackexchange.com/a/689291/148184 ) In my earlier Insight Spacetime Diagrams of Light Clocks, I stated without proof that the areas of all light-clock diamonds are equal. In my article, “Relativity on Rotated Graph Paper”, Am. J. Phys. 84, 344 (2016) I provided algebraic proof. In the penultimate draft, I had a non-algebraic motivating…

Quantum Physics via Quantum Tomography: A New Approach to Quantum Mechanics

January 8, 2022/123 Comments/in Physics Articles/by Arnold Neumaier

This Insight article presents the main features of a conceptual foundation of quantum physics with the same characteristic features as classical physics – except that the density operator takes the place of the classical phase space coordinates position and momentum. Since everything follows from the well-established techniques of quantum tomography (the art and science of…

Geodesic Congruences in FRW, Schwarzschild and Kerr Spacetimes

October 6, 2021/5 Comments/in Physics Tutorials/by ergospherical

Introduction The theory of geodesic congruences is extensively covered in many textbooks (see References); what follows in the introduction is a brief summary. Consider a 1-parameter family of timelike geodesics ##\gamma_s(\lambda)##, where ##s## labels each geodesic in the family whilst ##\lambda## is an affine parameter along each ##\gamma_s##. Then the vector field ##\xi \equiv \partial / \partial…

Corrections to MIT Open Courseware: Systems of Varying Mass

September 14, 2021/1 Comment/in Physics Tutorials/by Derek Bolton

Corrections to MIT Open Courseware 8-01sc classical mechanics, fall 2016 Applying Newton’s Laws to systems of Varying Mass PDF Course Link My concerns with the solutions provided on the cited MIT Open Courseware web page are, mostly: Despite arriving at the correct answers, the algebraic methods are invalid. As a result, they can be utterly…

How Quantum Information Theorists Revealed the Relativity Principle at the Foundation of Quantum Mechanics

July 25, 2021/12 Comments/in Physics Articles/by Mark Stuckey

This Insight is a condensed version of No Preferred Reference Frame at the Foundation of Quantum Mechanics. Reference numbers here correspond to that paper. This Insight is an expanded version of Quantum information theorists produce new ‘understanding’ of quantum mechanics. Feynman famously said, “I think I can safely say that nobody understands quantum mechanics” [1]. Despite…

Quaternions in Projectile Motion

July 15, 2021/2 Comments/in Physics Tutorials/by Neil Parker

Introduction In a previous Physics Forums article entitled “How to Master Projectile Motion Without Quadratics”, PF user @kuruman brought to our attention the vector equation ##\frac{|V_0 \times V_f|}{g} = R## and lamented the fact that: “Equally unused, untaught and apparently not even assigned as a “show that” exercise is Equation (4) that identifies the range as the…

When Science is Not Enough: Legal and Health Implications of Questions

June 26, 2021/7 Comments/in Physics Articles/by jack action

There are often questions on Physics Forums related to building machines or structures that are left unanswered because of this guideline (found in the Physics Forums Global Guidelines): Legal and Health Implications: Physics Forums reserves the right to remove and block discussion where there is plausibility that discussion may lead to litigation or affect ones…

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