Radiation in my living room

The University of the Third Age, U3A, was one of several positive discoveries made after I ‘retired’ as an academic and research scientist. It has, for instance, given me the opportunity finally to indulge in more creative writing – within a small group in which, comfortingly, I’m not the only person with a STEM* background. Some of the early-stage output from this endeavour is featured in a previous post (here). The other ongoing need in my life transcends the move from salaried employment to ‘going freelance’: trying to communicate science and my love for it to lay audiences. Although I’d been doing as much of this as I could fit in prior to retirement (e.g. see here or here or in umpteen other posts on this blog) and ad hoc invitations to do this have continued, I felt the need to go beyond one-off short talks. Again, the local branch of the U3A has provided a useful framework. And so it was that, last Autumn – my first year as a member – I opened my living room to a small group of brave souls who’d each paid £3 per session (to the U3A) in order to hear a complete stranger talk about glass. I had three two-hour sessions scheduled, so plenty of scope for peppering the science into a swathe of images and artefacts, art and history. The feedback was really positive, and word evidently spread that there’s more to glass than meets the eye (!) because my re-run of the course this coming autumn has far outgrown my living room and we are being moved to a larger venue in the city. This is hugely gratifying, but more importantly it helped to persuade me that my approach to presenting science in this context was broadly OK. However, talking about glass is, for me, an ‘easy’ thing – it can be harder to stop. I set myself a new challenge.

The opening slide: ready to welcome my brave audience.

One of the things I perhaps ought to take on, or so I told myself, perhaps naïvely, is the use of my training and experience in trying to demystify potentially more contentious aspects of the physical sciences … like radiation for example. It’s a topic I’d introduced to many Physics students over the years, so I had a bit of material to work with. However, the more I thought about it the more of that material I discarded. What was needed, I reasoned, was about an hour’s worth of material which I could spread over 90+ minutes to allow for questions and audience-led detours. The material needed to address the basic requirements of explaining just enough of the science and the terminology for everyone then to make sense of my attempt to introduce a more open-minded perspective than one often sees in the media. In the end I spent goodness knows how many hours researching and preparing new material that I thought might better do the job. In all this it was important to keep the talk grounded in contexts that one might readily appreciate: medical uses of radiation, radiation from the ground below and the sky above, nuclear power and the accidents we’d all have heard about, and so on. Part of this grounding required that we did more than stare at slides; thankfully, I have a Geiger counter on loan from my old department and managed to borrow a set of radioactive minerals from its hugely successful schools outreach team (here, run by a wonderful ex PhD student in my former research group); that would get us started.

The U3A run an annual series of ‘Summer Specials’: essentially taster sessions prior to members selecting what they might like to register for in the main programme, which starts each year in the Autumn. They also allow one to try out ideas for possible new courses, and this therefore provided an ideal vehicle for me. This is what I proposed:

Radiation: beneficial, benign and bad

Radiation, in its many guises, has been a ‘hot topic’ for more than 70 years and a matter of considerable interest of over a century – but how much do we know about it? In this taster session, we’ll take a look at its origins and effects – beneficial, benign and bad – from a scientific perspective. There ought to be no need for a formal science background beyond school-level, and questions will always be welcomed should you need to brush up on something. There will be a little radioactive material used within the session, but nothing that will represent a safety concern for any of us.

The registration list filled within a day or two, and a list of reserves began to form. There is evidently an appetite for such topics; so far, so good.

In the event, I found I had more than enough material for an hour’s worth of my talking. This was a good thing in the sense that it allowed all the space required for what turned out to be a large number of challenging, high-quality questions that emerged as we went through. The downside is that we had less time for connected discussion at the end, but addressing the questions as they arose was definitely of more importance. Indeed, for me, getting good questions is one of the best forms of immediate feedback.
What did we cover in the end?
After introducing ourselves and grabbing a drink and a biscuit or two, we spent a few minutes on the 92 naturally occurring elements and their 1000+ isotopes, and in establishing the prevalence of radioactive isotopes in particular. Next, an overview of the principal forms of ionising radiation and how one might tell which is which; then, how they can be detected using a Geiger counter, and what sort of units we measure them in (the Becquerel, Bq, and the Seivert, Sv, in our case). The final bit of scientific background covered the meaning of the half-life as well as illustrating the concept of the decay chain. No equations saw the light of day – reflecting an important lesson I learned long ago. All-in-all, with questions, we spent about half our time on the basic science before moving on to consider the bad, the benign and the beneficial.

I chose to reverse the order of the aspects of radiation drafted into my purposefully tantalising title: ‘bad’ is, in a very real sense, the easiest to cover – it is, well … bad.

‘Benign’ became, in practice, ‘unavoidable’: we looked at radiation coming from beneath our feet, e.g. from the granite beneath much of the UK’s West Country, and from space; we went on consider the raised levels experienced when flying and then to think through the consequences of the phrase “we are what we eat” in terms of radioactivity within our bodies. This was a good point at which to fire up the Geiger counter to get a sense of the natural background and to examine my borrowed collection of minerals. (The latter came with a thin sheet of lead in a plastic bag and the lid from a tin can – very useful tools in determining what sort of radiation our small lumps of rock were emitting.)

Our final topic came under the heading of ‘beneficial’, and here we looked at medical diagnostics and radiotherapy, at the formation of helium as a product of radioactive decay events within the Earth and at useful aspects of radioactivity such as carbon-14 dating within archaeology. We also considered the nett benefit of having radioactive events within the Earth since they help to heat the interior of the planet and thereby maintain our molten core: without this we’d not have a magnetic field to shield us from the solar wind, and we’d then suffer far, far more radiation from the Sun.

As I’ve said already, a constant theme was always to think in terms of perspective – the balance of risks. I wanted us to leave the session with an appreciation of what radiation is, where it originates, how much of it we encounter and what it does. My hope was/is that the group would thereby be better equipped – one might even say empowered – to engage with current and future debates. Reactions on the day exceeded all my expectations, and what people have kindly said in various emails since then has been truly humbling. One person made a very positive suggestion for improvement which I’ll definitely adopt. I doubt I shall ever forget the two people who, quite separately, said that had they been taught science like that when they were at school their later choices might have been very different. It doesn’t get much better than that.

My parting slide, philosophically tongue-in-cheek, is shown here. We could have spent an entire session exploring these three points alone – and perhaps one day we shall – but we ended our two hours together with the suggestion that they be mulled over. As it turned out, I was motivated to post a brief reflection on the middle one in the week after my U3A talk: here, should you wish to read it.

* STEM – Science, Technology, Engineering and Mathematics; sometimes an additional ‘M’ is added in order to include the Medical sciences.