Posts Tagged ‘RSSSE’

Talking about the SI

June 24, 2018

In just a few days, we will be setting up our stand about the International System of Units, the SI, at the Royal Society Summer Science Exhibition (RSSSE).

In May 2019 the world plans to redefine four of the base units of the SI. The re-definition represents a profound change in our concept of measurement.

And it involves quantities with which most people are familiar, such as ‘a kilogram’, or ‘a degree Celsius’.

So we have thought long and hard about how to communicate this at RSSSE.

Where to start?

The geographical theory of knowledge  suggests that ‘explanations of concepts’ are like ‘directions from one place to another’.

And thus, when people visit our stand, we are obliged to start giving ‘directions’ from where they actually ‘are’.

Although we want to talk about the re-definition of the SI, we have to acknowledge that most people don’t actually know much about the SI.

So if we want to ‘start from where people are’, we first need to explain what the SI is now, and why it matters. And that is what we have done.

It’s about Measurement.

In the ‘orientation’ for colleagues who will be helping at the RSSSE, we have stressed three starting points to help orient visitors to the stand.

  • At the heart of science and engineering, there is measurement.
  • Measurement is the comparison of an unknown thing against a standard.
  • In the International System of Units there are seven standard things against which all physical quantities are compared.

We then have seven hands-on demonstrations – one for each of the seven standard quantities (called ‘base units’)- which will hopefully serve as starting points for conversations.

Keep it simple!

In developing the ‘hands-on demonstrations we worked with the magical people at Science Projects to build apparatus that was robust and simple.

They have years of experience developing hands-on kit for museums and interactive science centres.

As we honed our initial ideas, Science Projects staff constantly challenged us to ‘keep it simple’. And in (almost) every case, their instincts were sound.

A demonstration which is engaging and which can be immediately grasped is a dramatically better starting point for a conversation than one which is beautifully sophisticated, but only elicits the Ah-yes,-I-see-now-moment after 5 minutes.

NPL Stands for the RSSSE exhibition

Stands for the RSSSE exhibition

NPL tweaks!

We developed the demonstrations and tried them out on NPL’s Open Day in May. The stands all survived and people seemed happy with the demonstrations.

But because we are NPL, and because at RSSSE we also need to interact with Fellows of the Royal Society, we had to add some truly complex and amazing features that are right at the forefront of science.

  • The ‘time team’ decided to develop an app that would allow people to compare the time on their own phones with the time from NPL’s Caesium atomic clock.
  • The ‘length team’ decided they wanted to develop a laser interferometer that would measure the height of SI-bots in terms of the wavelength of light.
  • The ‘mass team’ wanted to put an actual working Kibble balance on the stand at the Royal Society.

As I write this on Sunday 24th June, – none of these demonstrations are ready! But my colleagues are working hard and I am cautiously confident they will succeed.

If you get a chance to visit, the RSSSE is FREE and runs from Monday 2nd July 2018 until Sunday 9th July 2018.




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