All posts by Jonathan Sanderson

Science film-maker, writer, director and consultant.

Pendulums [2] – Phase

After the previous post I may have got a little carried away, and we’re declaring this Pendulum Week on Fresh pendulum action every morning.

This beautiful demo wasn’t something I’d seen before this film appeared, though the Harvard demos folks behind it trace its history to the University of Maryland in the early 90s, and from there back to Moscow State University previously. Everything old is new again.

Anyway, it’s a beautiful demonstration of pendulum periodicity and, through that, phase. Note that the previous pendulum demo was about the efficiency of energy conversion, and hence the only real link between these two demos is the pendulum itself. You may spot a theme developing here.

Pendulums [1]

The canonical pendulum demo is this:

It’s so well-known it was included in the recent BBC Challenger dramatisation of Feynman’s last great adventure, previously mentioned on this blog, only to my mind the dramatisation did it badly. With a longer pendulum drop the energy loss is minimal, and you really want your back and particularly the back of your head to be braced against a wall, as shown in the film above. If you stand in open space you’re at significant risk of swaying a little, and with a long enough pendulum you may have only millimetres of leeway.

It’s also one of those demos for which I’ve been wary of using volunteers. If they muck around at all they risk a bowling ball to the face, but sometimes a volunteer’s trust that you the performer wouldn’t let any harm come to them is stronger than their understanding of the physics. This is one of those situations where the science is considerably more reliable than the test subject.

Besides, I reckon the best way of performing this demo wouldn’t involve a person at all, but rather a priceless vase borrowed from a museum. Sadly, I’ve never seen it done that way.

Demos as political theatre

I’ve finally caught up with the BBC’s Challenger dramatisation of Richard Feyman’s last great adventure, which features this famous and terrific piece of science theatre. It’s sometimes referred to as an ‘experiment,’ which of course it wasn’t, really – the outcome was known and expected, and hence it’s a demonstration.

For our purposes, what it does rather neatly is illustrate the power of showing rather than merely telling, and remind us that such power is not limited to the realm of education. Challenger is plotted somewhere between a tense political stand-off and an engineering whodunnit, with Feynman’s famous O-ring demo as the climax. That a demonstration can serve such a rôle in a movie is something from which we should take heart. Sure, the circumstances were extreme, but if you ever find yourself doubting that demos can be dramatic: well, there’s a demo as the key moment in a drama. Appropriately enough for Feynman: QED.

Challenger is viewable on iPlayer for a few more days, and will doubtless be kicking around on torrent sites for a while longer, or if you’re not in the UK.

Too much information?

In a demonstration lecture we rely on the ‘demonstration’ to drive attention, and shy away from the ‘lecture.’ We run away from aesthetics, emotion and character, which leaves only exposition — and we’re at least dimly aware exposition is the dull bit. Best throw in another explosion.
– via StoryCog – Blog.

Yes, I’m cross-posting to my own site again. But it only looks bad because that laggard Shaha hasn’t written anything here yet. And really, read this, it’s good.

Minimal sequence of action

[cross-posted from the StoryCog blog:]

The sequence here which goes from hard light → hard shadow on scrim/Hitchcock gag → using that scrim to turn the same hard light into a soft source is very nicely thought-out. Sometimes demonstrations are about finding the minimal sequence of operations which makes your point.

Thinking about it, usually demonstrations are about finding the minimal sequence of operations which makes your point.

Banana voltaic pile

via Twitter this morning, chemistry lecturer Mark Lorch:


Potatoes? Yes. Lemons? Absolutely. Not sure I’ve seen a banana pile before, though. Mind you, if you’re going to build a little tower of the things you might as well use acid-soaked paper anyway…

Nice twist on a familiar concept.

ISS Photography

Time was, if you washed up on a desert island and wanted to predict celestial events to avoid being turned into stew, you had to judge things just right so your preferred island happened to lie in the path of a suitable eclipse. Thanks to advances in technology, you can now predict much more frequent and widely-visible, albeit less spectacular, heavenly events. Like visible ISS passes, for example.

I took this photo from the bit of grass opposite my house in northern England, July 2010. It’s a one-minute exposure, and yes, that streak of light has people in it.

We’re back

It’s … a number of years, I honestly can’t remember how many, since was live. Its original incarnation was as one of a slew of wikis which sprang up in the early 2000s, each attempting to catalogue science demonstrations. You’ll note that none of these efforts survive.

We know more about the dynamics of wiki communities now than we did then, and while we still think a wiki-like all-encompassing database would be tremendously useful to educators and entertainers worldwide, such a site would be a monumental effort. If somebody wanted to fund such a thing – well, StoryCog is good at managing that sort of project.

But we’ve been waiting (and occasionally machinating) for such a thing for years. It’s time to make something happen regardless.

Hence: this blog. It’s a spare-time thing compiled by enthusiasts. Mostly, we’ll post and link to demos we like, but we’ll also pull in notes and link to ideas around performance, theatre, design and other fields which impinge on the area of science as performance.

Welcome to