Relativity

Category archives for Relativity

A Quantum of Sunshine

It was nice and sunny this morning when I sat down at Starbucks to do some blogging, so I wrote a new Forbes post about the quantum physics that makes sunshine possible. This also brings in xkcd’s take on the fundamental forces, and even a little bit of SteelyKid. Sadly, it’s now grey and dreary,…

Science Story: Impossible Conditions

(When I launched the Advent Calendar of Science Stories series back in December, I had a few things in mind, but wasn’t sure I’d get through 24 days. In the end, I had more than enough material, and in fact didn’t end up using a few of my original ideas. So I’ll do a few…

I exchanged a bunch of emails a week or two ago with a journalist who was working on a story involving the possibility of faster-than-light travel. He wanted me to check some statements about the relationship between FTL and causality. FTL creates problems for causality, because if you have an object moving faster than light,…

General Relativity With Toddler Toys

A couple of times last week, I mentioned on Twitter that I was going to demonstrate relativity with toddler toys and string. This was an inspiration that hit late on Thursday, when I was trying to think of a better way to explain embedding diagrams (the technical term for those stretched-rubber-sheet pictures that everybody uses…

Quick Interstellar Thoughts

I’m teaching a Gen Ed course on relativity this term, which means I’m spending the last few weeks of the term discussing black holes. Which, in turn, means there was no way I couldn’t use that story about Kip Thorne calculating the appearance of a black hole for the movie. Especially since I have the…

Relativity and Baseball

It’s baseball playoff time, so sport shows are full of one of the great mysteries of the season, exemplified by this .gif (from SBNation): No, not “Raul Ibanez, really?” but “How can he make the ball go that far?” After all, even very good outfielders are lucky to reach home plate with a throw from…

Trains of Clocks

My Gen Ed relativity course has mostly been me lecturing about stuff to this point, so on Wednesday I decided to shake things up a bit and convert a chapter of David Mermin’s It’s About Time. The idea was to get students up and moving around a bit, and actually making some measurements of stuff.…

New Year, New Class: Gen Ed Relativity

The new academic year starts this week– first day of classes is Wednesday– and I’m dealing with the usual chaos associated with the influx of a new class of students. Who now look to me only a tiny bit older than SteelyKid and the Pip in the above picture (and if you think that sharing…

This coming fall term, I’ll be teaching Astronomy 052, “Relativity, Black Holes, and Quasars,” because the guy who has traditionally taught it (a radio astronomer who studies active galactic nuclei) has to do other courses instead. But I said “Well, hell, I’ve written a popular audience book explaining relativity. I can teach that.” And since…

Last week’s talks were using sci-fi space travel as a hook to talk about relativity, and my original idea for the talk was to explain how faster-than-light travel ultimately ends up violating causality. Some observers will see effects happening before the events that cause them, and that’s just weird. In How to Teach Relativity to…