I should probably run a ‘Wing Week’ here, but then I’d have to delve into explanations of how wings work. And we all know how messy that gets. So here’s a video from Ruesch Productions via the wonderful Fuck Yeah Fluid Dynamics, via @elinoroberts. I like demos on this scale, even if they’re more commonly known as ‘landing.’
Monthly Archives: April 2013
MAKE | Maker Faire UK: Interview with Artist Giles Walker
I want ScienceDemo.org to be about demos, yes, but also about issues surrounding demos – how and why we do them, to whom, and to what end. So here we go. Make have an interview with a guy who’s exhibiting pole-dancing, CCTV-headed robots at Maker Faire UK this weekend. Worth a read:
One of the things we discuss rather a lot in science communication circles is how to shift science and engineering further into mainstream culture. While the likes of Festival of the Spoken Nerd are taking great strides, it’s still notable that, for example, the ‘Cultural Olympiad’ surrounding last year’s London Olympics laughed all over the idea that STEM could be ‘cultural.’
This is one of the reasons I think Maker Faire is important. I’ve said before that while many STEM engagement projects are about STEM as career choice, Maker Faire comes from a completely different community and set of sensibilities. If it’s about STEM at all, it’s about STEM as lifestyle choice.
Maker Faire is chaotic, noisy, messy, and more than a little bewildering. It’s also joyous, inspiring, friendly, and pleasantly challenging. In my opinion it should be required reading on scicomms MSc courses, precisely because of that anarchic joy – it’s what happens when you take similar ideas to public engagement but develop them with a completely different group of people coming from a completely different viewpoint. In many ways, I prefer their interpretation of how things could be.
There’s a danger, I think, of the Cheltenham Science Festival and its ilk coming to represent ‘authorised’ science communication, and anything else being regarded with an air of suspicion (sometimes, when I’m hanging out with the London scicomms set, I wonder if this has already happened). There’s an orthodoxy to the sector which risks becoming bland. Maker Faire is doing a different job for a different audience, but the approach is so radical I think everyone should see it. Yet the usual scicomms community is notable largely for its absence. What should be worrying for them, I think, is how little they’re missed.
We’re not going to take STEM into mainstream culture unless we take the cultural sector seriously, and come to understand it on its own terms. Maker Faire UK is by far the best place to see the collision and interaction of the ‘two cultures.’ It’s a huge hit regionally, but I wish more of the opinion-makers and leaders made the arduous journey north to see it for themselves, and have their assumptions challenged.
Maker Faire UK runs April 27/28th at the Centre for Life, Newcastle. Details.
Status report
A brief post so you don’t think we’ve expired after the excitement of Pendulum Week, which was pretty much launch round here.
This is always likely to be a niche blog for a small audience, where by ‘small’ we mean, potentially, ‘millions of teachers and informal educators worldwide’. So I’m pretty darn delighted we’ve drawn well over a thousand page views so far. As sites go that’s pretty crap, but for what’s currently a spare-time/hobby project by a couple of obscure specialists it’s a decent start.
We’ll continue bringing you joyous demo links and musings on the art and craft. We’ve several more theme weeks planned (not yet sure of the schedule for those, though), and a few guest and contributing posters lined up to save you from our particular blether.
One thing I do want to do is find a more appropriate theme than this, specifically one which does a better job of surfacing comments. There’s ‘minimalist’ and there’s plain invisible. So if the site looks completely different on your next visit, that’ll be me trying out some alternatives.
Meanwhile – do drop us a line with your favourite demos, or your thoughts. There’s a contact form at the foot of the page.
Pendulums [6] – Coriolis Effect
Enough of the deep-and-meaningful musings, I’m going to wrap up Pendulum Week with perhaps my favourite pendulum demo of all time. “Foucault’s!“, I hear you cry?
Well, firstly: no need to be rude. Second: actually, no. Well, sort-of no. Which is to say, yes. Ish. Only without the… er… pendulum. Look, here it is:
…and I’ll let you, dear reader, work out what to do with this one. Lovely demo.
Pendulums [5] – Not Resonance
As Pendulum Week continues here you’ll have noticed a pattern building up: that pendulums crop up in all sorts of demonstrations, but it’s often rather tricky to pin down satisfying explanations for their behaviour. Pendulums appear simple and straightforward to grasp, which is usually a good sign for demonstration tools as we want audiences to engage with ideas or behaviour and not be distracted by unfamiliar apparatus. However, I wonder if it’s possible that pendulums are too simple, in that their apparent simplicity seems to lull us into forgetting their subtleties.
Heck, unless you’re in that sin θ ≈ θ small-amplitude space you haven’t even, technically, got simple harmonic motion. Most of the time, pendulums don’t even swing like, well, pendulums. Ouch.
It feels like it ought to be possible to link pendulum demonstrations together in a neat story. A mass on the end of a string is about as simple as physics apparatus gets, surely there’s a delightful sequence of demos which can build successively, one on the other, to arrive at something complex and surprising and revealing about the world? That’s got to be possible, right?
Perhaps it is, but the origin of this series of posts lay in my noticing that pendulum demos aren’t alike, and the distinctions seem to me to be of the subtle-and-confusing kind rather than the subtle-but-illuminating kind.
Probably the best attempt I’ve seen to navigate the resulting swamp was by my colleague Marty Jopson, who made this film for the first series of Science Shack (skip to 2:40 for the start of the show):
Marty and I were co-producers on the series, and if I remember correctly he won awards for this show. I wasn’t, I should say, much involved with this episode (harrumph), but it’s still worth a watch. It gets into some of the subtleties about resonance and synchronisation that we’ve seen in this series of posts.
Pendulums [4] – Synchronisation
In the previous post, pendulums of the same length (and hence the same natural frequency) oscillated each other. Here, the point is that the pendulums are of slightly different lengths. And yet:
Comprehensive notes can be found in what appears to be the original source of this demo, Bryan Daniels’ senior project at Ohio Wesleyan University.
To my mind this demo isn’t an example of resonance… and that’s a thought we’ll pick up in the next post in this series. Meanwhile, please do share your favourite pendulum demos in the comments. Or, you know, any pendulum-related anecdotes – there’ll never be a better time for those.
Pendulums [3] – Coupled Pendulums
Pendulum Week heats up with… coupled pendulums:
(First embed, doubtless of many to come, from the prolific Brady Haran at Nottingham.)
Look in any of those interminable/popular[delete as applicable] ‘Exciting Fun Science Things to Do on a Rainy Day! Science!‘ books and you’ll likely find this old standby, more commonly done with potatoes rather than creme eggs.
It’s not one of my favourites, partly because I think it needs careful performance to appear as amazing as is usually claimed, but also because the subtlety of explanation required hardly seems worth the effort. This film, for example, doesn’t tell us very much. The explanation bit goes:
“There are little forces as [the connecting string] goes out of line that pull from one to the other, transferring energy from [the first pendulum] … over to that one, and then back again.”
Hmm. All that’s doing is describing what we see and replacing the word ‘swing’ with ‘energy,’ and I’m not a big fan of using ‘energy’ as an arm-wave explanation. Robert Winston’s book, snarkily linked above, explains pendulum movement in terms of gravity and momentum, then adds:
“If two pendulums are attached to the same piece of string, they pass their motion back and forth between each other. One pendulum swings, pulling the string it’s hanging from to and fro. This transfers energy to the second pendulum, which starts swinging itself.”
…which, again, is a reasonable description. Is it an explanation, though? I’m unconvinced.
Neither of these ‘explanations’ has begun to cover why it matters that the pendulums are the same length, let alone pesky details like: the demo still works if the connecting string is perfectly taut, when the driving force is delivered by torsion at the suspension point rather than lateral displacement.
But when you try to write a more satisfying explanation you end up in a bit of a mess. I know I did when I wrote this demo into a children’s TV series back in about 1998. A satisfactory explanation has to include (or at least skirt around) energy exchange, mechanical impedance, and resonant frequency – the sheer amount of physics required is, to my mind, beyond what the demo itself will support.
Better, I think, is this variation:
…which is much more clearly about resonance. The inverted spring pendulums also break the visual connection with the phase demonstration in the previous post in this series, which I think would reduce the risk of confusion were one to attempt linking several of these demos together.
Pendulums [2] – Phase
After the previous post I may have got a little carried away, and we’re declaring this Pendulum Week on ScienceDemo.org. 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:
http://www.youtube.com/watch?v=vQhNEw2seNs
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.
Rehearse!
A simple tip for any science communicator, or indeed teacher, intending to perform a demonstration to an audience:
Make sure it works.
That’s it.
It’s such obvious advice it almost goes without saying. Almost, but not quite. Sometimes we become so confident in our performance skills that we forget the basics, and this post is prompted by my having seen two prominent UK science communicators recently do demos which didn’t work.
I’m not going to mention any names and I’ll leave the details vague: this isn’t intended as a personal attack. I’m much more interested in how the demonstration failures felt from where I was sitting at the time – in the audience.
“I’m going to try to do a demonstration which never works.”
One of the first bits of advice you’ll receive as a performer is: never apologise. The above line called that to mind, along with the obvious response: “Well, why are you going to do it?”. My hope was that famous science communicator #1 was joking for effect, but he proceeded to spend several minutes of an otherwise fascinating and engaging lecture on an incomprehensible demo involving members of the audience having to stand up and sit down according to a set of instructions neither they nor the rest of the audience seemed to understand.
As best I can tell, the ‘demonstration’ failed to illuminate the bit of science it was meant to illustrate. Certainly, it added nothing to an explanation which had already been provided with a diagram. The lecturer even admitted as much. So why include the demonstration at all?
Perhaps because we’re so enslaved to the notion that we must entertain our audiences with demonstrations that we’ll shoehorn one in if there’d otherwise be too much exposition. Or perhaps the lecture was simply too short otherwise.
From the audience’s perspective, all the demonstration achieved was a measure of audience embarrassment.
Famous science communicator #2 did a demo which simply didn’t work. It was supposed to illustrate that chemicals of a certain family were all good fuels, and it involved separating the wick from the wax of a tea-light. The wick was then squirted with body cream and lit: the body cream would melt, flow up the wick, vaporise and burn.
It didn’t.
The wick caught fire, but it didn’t melt the body cream and it certainly didn’t work as a candle. So, again, an under-prepared demonstration which made the audience uncomfortable, except that communicator #2 proceeded as if it had. The lecture – a team effort – carried on without him, and he distracted me as I watched him continue trying to make it work. He was clearly puzzled as to why it hadn’t.
Prior to doing the demo, science communicator #2 had joked that he had only purchased the cream a few minutes before the lecture, making light of his under preparation. And that was the problem, obviously – he hadn’t checked his demo. He’s a busy man, but I think the audience deserve better. So did the non-geek friend with whom I attended the lecture, who was unimpressed by this demonstration and a number of other shortcomings which we’ll cover in later posts.
Most science communicators are scientists themselves, and we’re accustomed to the idea that science doesn’t always, well… work. Our audiences, however, often aren’t as comfortable with the nuances of statistical repeatability. Every time a demo doesn’t work, we risk the inference that science doesn’t work. Dangerous.
In a classroom situation, however, discussing with your audience (students) why they think the demo didn’t work and – time permitting – trying to fix it can be tremendously instructive.