Knowledge Hub

A couple of weeks back I posted an answer to a question from a Twitter follower’s child, who asked “How Strong Is Space?” That was fun, so here’s another kid-question answered, this one from my own eight-year-old who goes by “The Pip” for Internet purposes. The other night, he asked “Why can’t atoms touch each other?” I’m not sure the exact reason why he asked this, but the phrasing suggests it’s related to the observation that there’s almost always some microscopic empty space between things that appear to be touching on a macroscopic scale. Possibly it’s even connected to the “Atoms are mostly empty space” idea that Ethan talked about recently. The short and simple version of the answer is that it’s not really correct to think of atoms as solid objects like little balls that can be forced into physical contact with one another. Most of the “size” of an atom is just the electron cloud that surrounds the nucleus, and that’s not a solid thing— it will shift around in response to electri

I greatly enjoyed David Kaiser’s How the Hippies Saved Physics (here’s my review from 2011), so when I ran across a mention of this new book with “Quantum” in the title, I immediately sought out a copy. This sort of thing is highly relevant to my interests. Kaiser is a professor at MIT with a joint appointment in both physics and history of science, and as you would expect this collection of essays splits time between those two fields. The book contains a handful of pieces relating to Kaiser’s work in physics, chiefly about a “cosmological” test of quantum physics, using light from distant quasars as a random number generator for a Bell’s Inequality test (I talked briefly about this idea in the context of football in 2015). There are also a larger number of pieces primarily about the historical and social context of physics, mostly in the mid-to-late 20th century. Almost all of these were previously published (I think there’s only one that doesn’t have a “A version of this previously..

As someone who derives significant income from writing for money, I end up spending a fair bit of time reading writing advice. Not because I'm in need of tips, myself-- after many years of this, I've got a routine that mostly works for me. Rather, I'm looking for good advice to pass on to other people, because I get asked for advice on a regular basis, and I don't really have much of my own to offer. That's how I came to read this advice post from Alyx Dellamonica, making an analogy between figuring out how fiction works and trying to learn about cars from a junkyard. I like the junkyard analogy quite a bit, but along the way she makes a couple of passing mentions to physics that I absolutely hate. Here's the first: With the arts, you not a physics professor laying out a formula, some cut-and-dried procedure for which there is one satisfactory answer. You’re not showing someone how to paint the perfect yellow line down the middle of a strip of road, or fly an ai

Helium Atom problem Evaluation of wave function and Energy  Approximation Method  Using Variational principle Many-Body problem Link to see the paper https://www.scribd.com/document/392492158/Helium-Atom-Graduate-Text-How-to-find-the-wave-function-and-Energy If you want to understand how to evaluate the He- atom wavefunction, You need to click on this. I have derived in a rigorous manner. To get more problems to be solved you can suggest me some problem to evaluate. I will write one book on Quantum Mechanics to handle its concept and how to use in a mathematical way to solve problems.