quantum mechanics

Astrophysics / cosmology / Physics / etc.

Dark Energy, Numerical Relativity, and Astrophysics

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binary neutron star merger

So I did an interview for the “Tilting at the Universe” podcast. In it, I describe: the history of dark energy and the expanding universe, how the mystery of dark energy may be solved once we reconcile quantum mechanics and general relativity, how the astrophysics of black holes and neutron stars may help us understand quantum gravity, and how my field of numerical relativity fits in to all of this. I think I did a pretty good job of explaining what excites me about the field. So check it out. The interview is here. In the interview, I mention

Physics / Quantum Mechanics / Relativity / etc.

The Holometer

jonah

You may have heard the buzz about the holometer, shown in figure 1, before. It’s a giant laser interferometer, much like those used to search for gravitational waves, designed to detect quantum fluctuations in the fabric of spacetime. At least, that’s the claim. The holometer just released a preprint of their first science paper. And of course,  a Fermilab press release appears in Symmetry Magazine. The article is good, and I recommend you read it. And the holometer experiment is good, interesting science. But I have to say, I’m extremely annoyed by how much the holometer team is overselling their

Physics / Quantum Mechanics / Science And Math

Aharonov-Bohm Effect

Michael T. Schmidt 1

Since I was busy last week and I’m feeling ill this week, my good friend Michael Schmidt has agreed to write a guest post for me this week. Mike has a masters degree in physics from the University of Colorado, an interest in teaching, and a passion for math and physics.  You can find out more about him on his personal website or read more on his blog, duality.io. So, without further ado, here’s Mike’s article. Force Vs. Energy When we teach physics, usually force is one of the first concepts. Force is easy to understand. I can have

History / Physics / Quantum Mechanics / etc.

Spin and the Stern-Gerlach Experiment

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The word “quantum” means a single share or portion. In quantum mechanics, this means that energy comes in discrete chunks, or quanta, rather than a continuous flow. But it also means that particles have other properties that are discrete in a way that’s deeply counterintuitive. Today I want to tell you about one such property, called spin, and the experiment that discovered it: the Stern-Gerlach experiment. (The goal of the original experiment was actually to test something else. But it was revealed later, after the discovery of spin by Wolfgang Pauli, that this is in fact what Stern and Gerlach were

Physics / Quantum Mechanics

Sometimes a Particle Isn’t Possible

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Last time, I showed you how you could construct a photon, a light particle, in a configuration of mirrors called a ring cavity. This time I’ll show you that sometimes, you can’t make just one particle—they only come in pairs. And sometimes, the notion of a particle doesn’t make any sense at all. (This post relies heavily on last week’s post, so if you haven’t read that, I recommend you do so.) Disclaimer: What I’m about to describe is only the simplest case, and I make simplifications for the sake of exposition. It is possible to capture and manipulate

Physics / Quantum Mechanics / Science And Math

What’s in a Particle?

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If you’ve read or heard anything about quantum mechanics, you’ve heard the phrase “particle-wave duality.” The common wisdom is that this means that particles sometimes behave like waves and sometimes behave like particles. And although this is right, it’s a bit misleading. The truth is: Everything is always a wave. It’s just that waves can be made to behave like particles. To see what I mean, let’s actually show how one can make a set of waves behave like a particle. Specifically, let’s show how a set of light waves can be made to behave like a photon, a light particle.

Physics / Quantum Mechanics / Science And Math

Quantum Field Theory in A Cavity

jonah

So I’m still mired in final exams–this time a final project for my quantum field theory course.  The downside is that it will be yet another week before my next “real” post. The upside is that I still have a little something for you all this week. The above image shows part of what I’m working on for my project. Imagine that you make a square box of mirrors, and with some magic quantum tweezers, you put exactly fifty-one photons into your box. Light is a special oscillation in an electromagnetic field, which we usually describe classically. But if

Mathematics / Science And Math

Probability: Part 2 (Distributions)

Michael T. Schmidt 4

Editors Note: This week, I’m busy with final exams here in Guelph, so my good friend Michael Schmidt has graciously agreed to do a guest post. Thanks, Mike! Hi everyone! Since last time I decided to talk about the basics of probability, I thought this time I would expand on that subject. In part 1, I discussed how to count different possible outcomes of random events and determine the likelihood of particular events. If you have not read that, or it’s been a while, you should read over Part 1. This method is great when where are relatively few possible

optics / Physics / Quantum Mechanics / etc.

Scattering Part Two: A Quantum of Scattering

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We come spinning out of nothing, scattering stars like dust! ~Jalāl ad-Dīn Muhammad Rūmī Last week, I explained Rayleigh and Raman scattering from a classical point of view. In the process, I explained why the sky is blue and introduced Raman spectroscopy, a powerful tool for studying the structure of molecules. This week, I fill in the gaps and explain scattering from a quantum-mechanical point of view. Before we can talk about scattering, though, we need to review some important ideas from quantum mechanics: energy levels and the Heisenberg uncertainty principle. Energy Levels The story of energy levels starts

optics / Physics / Quantum Mechanics / etc.

Why The Sky is Blue: Lord Rayleigh, Sir Raman, and Scattering

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The Sky is the Daily Bread of the Eyes ~Ralph Waldo Emerson   At some point in his or her life, almost every child on Earth asks, “Why is the sky blue?” The question is so prevalent that, to me, it has come to represent the wonder that the world holds for a a child. Adults don’t ask such questions… at least, not unless they’re scientists. Part 1: John Tyndall In 1859, physicist John Tyndall thought he’d found the answer to the sky’s color. His studies of infrared radiation required him to use containers of completely pure air. He