World Metrology Day!

So, of course, I missed World Metrology Day, which was Wednesday. There weren't many parades, but there was this article on the BBC: Measurement science's odd pursuits, which features a project I worked on (scroll down until you see a car full of balls) alongside Dr. Nick McCormick, Grant Klimaytys, and Richard Shaw.

The project wasn't exactly hard science: we were to provide some interesting facts about a SMART car to go with an advertising feature on the New Scientist website. The full project was more involved than it might seem from the image in the news story - my colleagues also performed impact tests on the door panels, did braking tests using a portable thermal imaging camera to measure the heat of the brake discs, and modelled the turning circle compared with a London black cab and a family car (I wrote a java app to generate a little movie demonstrating this).

Inevitably, of course, a car full of ballpit balls provided the most eye-catching image for the project. Using balls to gauge the internal volume of the car was not the first idea we had - water or fine sand would have provided a more exact measurement, but of course would have rendered the car pretty much unusable. I suggested that we might seal the car up and pump the air out of it - thinking that once the inside of the car was a vacuum it might be possible to measure the force required to maintain that vacuum and calculate from that the size of the cavity. I'm not sure whether that's theoretically possible or not, but it certainly wasn't practical - since we had decided making the car watertight would be extremely difficult, making it airtight would have been even harder.

Eventually the ballpit ball idea came up, and it had quite a few arguments in its favour. Ballpit balls are (roughly) spherical, and although spheres do not pack well, the theoretical maximum packing density (74%) is well known (although experiments tend to measure something closer to 68%) - so it would be possible to derive a reasonable actual volume from the number of balls and their size.

From another viewpoint, Ballpit balls are also (roughly) the size and shape of a human fist. So they can measure the total usable volume, since internal spaces in the car that a person can't get at could be considered useless for the purposes of comfort (the idea of measuring the internal volume was to compare it with externally larger cars and show how well it compared).

The final argument, of course, is that it would be fun, and might allow us to buy a whole load of ballpit balls that we would then be able to use for other projects (such as these).

Unfortunately, it turns out to be harder to get that many ballpit balls than it looks, especially in a short time. Even with the example and instructions from Last.fm, we were unable to get enough balls to do the job (at one point someone from purchasing failed a saving throw against math and told us that we'd only need 400 balls - uh no).

Fortunately for us, Grant (who was responsible for this part of the project) was only a few years out of university, and his blagging skills are top-notch. He got in touch with a local children's play area and persuaded them (for a small fee) to stay open late one evening while we borrowed the contents of their ball pit.

So later that week, Grant, Richard and I rolled up to the playgroup at closing time and parked the SMART car by the fire exit (the closest point to the ballpit). Together with Grant's cousin Kate, we ferried baskets of balls out of the building and poured them into the car, all the time praying that the rain that kept threatening to fall would pass by.

Once the car was full, we then started the laborious process of counting out each ball - not only time-consuming, but physically awkward, since we could not open the car doors without losing the balls all over the road. Eventually we hit upon the idea of lifting Kate into the car so that she could pass out armfulls of balls for us to count.

The total eventually came to 3441 (the 1, if you're interested, occupying a fist-sized space between the windscreen and the dials), from which Dr. McCormick (using a packing density of 68%) calculated an internal volume of 1.1 m³. Although they may not have been the most accurate measuring tool I have ever used, they were certainly one of the most fun and easy to work with.

Indeed, the only way it could have been any better would be if there were well-known numbers for the maximum packing density of ducks.

L'Oreal respond, but decline to show their working.

Dear L'Oreal,

I'm very interested in your advertising claim (the Eva Longoria-Parker advert for Extra-Volume Collagene Mascara), that it provides "up to twelve times more impact in a single glance". How is this measured? I used to work with some experts in impact testing, and as far as I could tell most of their tests involved dropping metal balls onto sheets of various materials. Is it a similar procedure in a cosmetics lab? I understand Mrs. Longoria-Parker has a bachelor's degree in science, does she help out personally with the tests? It seems like that would be a good idea - I guess she's very successful at the moment, but you never know when it's good to have another job to fall back on.

Thank you for your time, I look forward to your answers.

L'Oreal's response:

Dear Mr Lawrence,

Thank you for your recent email and for showing interest in our company. I can advise that we use Hydra Collagen in the Extra Volume Collagen Mascara. This is known for its volumising properties and lashes are instantly plumped up and full of body. From extensive laboratory tests carried out, we can ensure that this product is suitable for the purpose for which it has been designed for and is of the highest standard.

It seems to me that L'Oreal are telling me that they have performed the required safety tests - which is nice, but nothing I didn't expect anyway. But their claim? Marketing nonsense, clearly.

If looks could kill (by blunt force trauma)

One of L'Oreal's current offerings on UK tv promises "up to twelve times more impact in a single glance". Is it too much to hope that their shill (in this case straight-out-of-stepford BSc-wielding actress Eva Longoria-Parker) happened to be shown a copy of that research paper before she was shown the script?

Yes, it probably is.