July 2014

The other day I was playing with some soap bubbles and I started thinking: what makes them pop? And furthermore, sometimes they don’t pop, instead they will shrink down to nothing. So what causes each of these different behaviors? Can the failure mechanism be predicted? Can you predict when it will fail?

Basically the collapse of the bubble can be attributed to one of two mechanisms. 1.) The air inside of the bubble diffuses through the bubble film, causing the bubble to shrink and eventually collapse. 2.) The liquid in the bubble film evaporates, causing the film to get thinner and thinner until it finally ruptures, causing the bubble to pop.

First I’d like to analyze the bubble shrinking and collapsing, but I’ll split it into a series of posts. The first few will be brief explanations of specific pieces of physics that are needed in order to perform the analysis. The order I think I’ll do them in is the following:

1. Fick’s Law
2. Quasi-steady-state Approximation
2. Henry’s Law
3. Ideal Gas Law
4. Laplace Pressure
5. Geometry Simplification

Then I’ll show how to put all those pieces together to derive a single equation that shows how long the bubble will last until it collapses.

Or I might change my mind on the structure and the order part-way through. We’ll see.




Still with much too much free time on my hands, I’ve started re-watching Highlander: The Series, which is conveniently on youtube in its entirety. Some thoughts so far in the first season (which originally showed back in 1992, over 20 years ago!):

The series seems to hold up pretty well overall. The acting is decent, and the casting is good as well. Englishman Adrian Paul is a million times more believable as a Scotsman than Christopher Lambert ever was. Alexandra Vandernoot playing Duncan’s love interest is as exotic and sexy as I remember her, however some parts of 90’s fashion haven’t aged well, which is most noticeable with her costumes: her high-waisted jeans look like mom jeans today, and she (and all the other women in the show) have big poofy hair that looks pretty silly to our current norms.

Production values are good, and it turns out that the show had quite a big budget for a TV show: it was financed and broadcast internationally, allowing it to make profit from numerous markets all over North America, Europe, and Asia simultaneously. With so many financial backers, I don’t know how the producers and directors managed to avoid having everything about the show ruined by a committee, but they seem to have managed it somehow.

Getting Christopher Lambert to do a cameo on the opening episode was excellent: their characters Connor and Duncan McLeod really have great chemistry together, it’s a shame that Lambert didn’t agree to do any more episodes.

Of course my memory tells me that the show really went downhill on the last two seasons, but I’m still on the first season and I’m really enjoying it.

Now is the time of year when my wife and kids go back to Japan for a major portion of the summer, so I find myself with lots of (i.e. too much) free time. While I always have goals of doing something productive, it usually ends up with me playing lots of video games and watching lots of shows or movies.

So I just finished watching a web series called Street Fighter: Assassin’s Fist. Basically it’s 12 10-minute episodes, so total it’s about the length of a full-length film. And I really enjoyed watching it. I’m not extremely knowledgeable about the back story and such of the Street Fighter characters just that Ryu and Ken both use a style called 暗殺拳 (ansatsu ken or assassin’s fist), and that they were both best friends and rivals. I also knew that there was a 3rd character that used the same style named Akuma (Japanese for demon), and that he was antagonist of some sort. That was about it.

Anyway, I was really impressed when I saw it. It wasn’t silly and campy like the old Street Fighter movie with Raul Julia. The dialog is mostly Japanese with subtitles, and in fact all of the Japanese characters are actual Japanese actors, with the sole exception of Ryu played by Asian American Mike Moh. Even then both him and Ken regularly speak Japanese in the show. Overall I’d say that it’s probably the best film based off a video game that I’ve ever seen. If you played Street Fighter back in your youth, I think you’ll like this.