Astrophysics / cosmology / Physics / etc.

Dark Energy, Numerical Relativity, and Astrophysics

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 / Relativity / Science And Math

Classical Tests of General Relativity

Abanonded steam engine in Uyuni train cemetery

Last Wednesday, November 25, was the 100 year anniversary of general relativity. It was the precise day that Einstein presented his field equations, shown in figure 1, to the world. In celebration of this anniversary, today I present to you some of the early triumphs of general relativity, classical predictions of the theory that have been precisely tested and where theory has exquisitely matched experiment. This is the sixth instalment of my howgrworks series. Let’s get started. The Perihelion of Mercury Before Einstein, we believed that the motion of planets in the solar system were governed by Kepler’s laws

Physics / Quantum Mechanics / Science And Math

Bruno Maddox and the Magnet: A Story of Misconceptions

This week the ever-inquisitive Gary Matthews pointed me to a 2008 article for Discover Magazine by Bruno Maddox, claiming that physicists cannot explain how magnetism works, and that they are in denial about it. I encourage you to read the article. Maddox is wrong—dead wrong—but his argument displays a number of common misconceptions about science. And I’d like to address some of them. The most important misconceptions Maddox displays are that of first cause, of classical intuition, and of distrust of the abstract. Let’s get started. (DISCLAIMER: The opinions in this article are my own. I will be describing

History / Physics / Relativity

The Men Who Weighed Mountains

 In 1687, Sir Isaac Newton published the Philosophiæ Naturalis Principia Mathematica, his magnum opus describing the laws of motion and the secrets of the universe. One such secret is Newton’s law of universal gravitation, which states that the same gravitational force that pulls us down to the Earth holds the planets in their orbits around the sun. Indeed, every mass attracts every other mass through gravity. This means that not only are we pulled downwards towards the Earth, but we are pulled towards pieces of the Earth. We are all gravitationally attracted to mountains. In fact, this is an excellent test of Newton’s

Astrophysics / Physics / Science And Math

Pope Francis says Evolution and the Big Bang are Compatible with Catholicism

You’ve probably heard, the news. Pope Francis has announced that Big Bang cosmology and evolutionary theory are compatible with Catholicism and “may even be required.” This is, of course, wonderful news. It’s evidence that science and religion are not necessarily incompatible and that people of faith can modify their beliefs based on the evidence around them. But it should have been this way all along. Indeed, it originally _was_ this way. One of the people who developed Big Bang cosmology, Monseigneur Georges Henri Joseph Édouard Lemaître was a catholic priest who believed that his studies of physics brought him

abstract algebra / History / Mathematics / etc.

International Women’s Day Spotlight: Emmy Noether

The connection between symmetries and conservation laws is one of the great discoveries of twentieth century physics . But I think very few non-experts will have heard either of it or its maker[:] Emily Noether, a great German mathematician. But it is as essential to twentieth century physics as famous ideas like the impossibility of exceeding the speed of light. It is not difficult to teach Noether’s theorem, as it is called; there is a beautiful and intuitive idea behind it. I’ve explained it every time I’ve taught introductory physics. But no textbook at this level mentions it. And

cosmology / Physics / Relativity / etc.

Always Walk Away From An Explosion—The Story of the Big Bang


We were fortunate to be there a day or two before ‘the big bang’ and then we got the heck out of town. ~Scotty Moore A few weeks ago, +Matthew Villaneuva asked the following question on Google+: Does anybody else find the Big Bang (the scientific explanation on how the universe got created) weird? Actually, yes! Just a century ago, everyone believed that the universe was static—i.e., that it had always existed and that it would always continue to exist. Even Albert Einstein held this view. I previously explained why we know the universe is expanding, so I’m going