Built on Facts

Boy howdy do we love spheres in physics. Sure we might tell you that the reason involves deep truths in topology, and symmetry, and group theory, and all that mathematical arcana, and in fact there’s a lot of truth to that. But if we’re completely honest, or at least if I’m completely honest, I have…

Sunday Function

A reader asked me about the hyperbolic trig functions, sinh(x) and cosh(x). What are they for, and do they have an intuitive interpretation in physics? That’s a pretty good question. After all, most of the time you first meet the hyperbolic trig functions in intro calculus, where their rather odd definitions are presented and then…

Our department here at Texas A&M has a student chapter of the Optical Society of America, and each week a student or professor gives a talk about something interesting while the rest of us eat pizza. I’ve been working on and off on a talk I’m going to give, tentatively titled “Just what the @#$%…

By the 1860s, the classical theory of electricity and magnetism was on a very solid theoretical footing. Maxwell’s equations describing the interplay of charges and currents with electric and magnetic fields were on paper by 1862, and with some changes in notation they’re the exact same today. Relativity wouldn’t be invented for another half-century or…

Phil at Bad Astronomy opined (and it is a common opinion) that the supernatural is incoherent: If you posit some thing that has no perceivable or measurable effect, then it may as well not exist. And as soon as you claim it does have an effect — it can be seen, heard, recorded, felt —…

Sunday Function

Head down to Box Office Mojo and pull up the list of the top grossing films of the year thus far. Seven of the top ten have a dollar gross beginning with the number 1. Okay, that’s not too weird. Big films tend to pull down somewhere between $100-200 million, while only the real monsters…

Here is a picture of (I think) Maru the cat playing in a bag. He loves bags. Here is the same picture of Maru, at half the size: Now imagine that Maru is a physicist and the pictures are not pictures but instead windows into the universe he occupies, separate from ours with (possibly) its…

Gauss’ Law PROVED WRONG!

Just though I’d try writing a post title in the style of a crank. Kinda fun! Gauss’ law, of course, is not wrong. But I got a question from a reader that deceptively simple and an interesting example of a theorem not quite working the way you’d expect. I’ve gone over Gauss’ law before, so…

Thoughts on Osama

Some initial thoughts, on a beautiful day in a palpably better world without Osama: 1. I’m astonished he was still alive. I was certain he died from an anonymous bomb or health problems sometime between ’01 and ’04. He hadn’t released any tapes or videos with unambiguous confirmation of when they were recorded, and the…

Enforcing the Cosmic Speed Limit

Last time we took a pulse of light and shot it through a medium with a frequency-dependent refractive index. The particular form of the refractive index was sort of interesting – for some frequencies, it was less than 1. That implied that the phase velocity of a sine wave would be faster than the speed…