Archives for October, 2025 - Page 2
Universal Expansion Clock: Why the Big Bang Was Infinitely Long Ago
Milne’s Expansion Clock: Why the Big Bang Is “Infinitely Long Ago” This explains how, in Milne’s kinematic relativity, using the rate of expansion (or its integral) as the universal clock…
Slow Moving vs Fast Moving Electrons – Photon Interaction
Electron–Photon Interaction: Slow vs Fast Electrons Is There a Difference Between a Slow-Moving and a Fast-Moving Electron Interacting with a Photon? Yes — the interaction depends strongly on the electron’s…
Particle in an Infinite 1D Square Well — Momentum Distribution
Momentum Distribution for a Particle in an Infinite 1D Well Also read - Particle in a 1-D infinte well - Energy States Setup Infinite well from \(0\) to \(a\). The…
Wave Packet Velocity Derivation
Group and Phase Velocity of a Localized Wave Packet Group and Phase Velocity for a Localized Wave Packet Build a Wave Packet Consider a superposition of plane waves centered near…
Particle in an Infinite 1D Square Well — Energy States
Energy States of a Particle in an Infinite 1D Square Well Setup Consider a well of width \(a\) with potential \ The time-independent Schrödinger equation (TISE) inside the well is…
Particle in a Box? Momentum and Distance Traveled – 1-Inch box to Atomic Scale Box
How “Stationary” Is a Particle in a Box? Momentum and Travel Distance from 1-Inch to Atomic Scales How “Stationary” Is a Particle in a Box? Momentum and Travel Distance from…
Momentum Space Representation of the 1\r Operator
Momentum Space Representation of the \( \frac{1}{r} \) Operator The operator \( \frac{1}{r}, \quad r = |\mathbf{x}| \) plays a central role in quantum mechanics, especially in Coulomb potentials,…
Estimate the nuclear radius size based on Electrostatic and Magnetic Field Strengths
The Rasetti–Fermi Paradox: Electrostatic vs. Magnetic Radius of the Nucleus The Rasetti–Fermi Paradox (1926–1927): Two “Radius” Estimates That Don’t Match A historical back-of-the-envelope puzzle: estimating a nuclear “radius” from an…
Time near the event horizon
Time Near a Black Hole’s Event Horizon Also read 'Tidal Forces inside a black hole' A clear relativistic description of what happens to time near the event horizon, seen from…
Tidal Forces inside a black hole
Tidal Forces for a 100 kg Human Falling into Black Holes Tidal Forces for a 100 kg Human Falling into Black Holes We quantify tidal accelerations for a 100 kg person of…