# Bang! goes the science

Last night, the BBC showed a Bang Goes The Theory special, examining how many cyclists it would take to power an average family’s home across a single day.

For the most part, it was an interesting if not intellectually stimulating look at how much energy we can use and waste without even noticing. We had shots of the family cooking, cleaning and gaming, interspersed with clips of increasingly desperate cyclists trying to keep the whole shebang running. If the voltmeter felt in to the red, that’s it: fizz, fail, power gone.

Every so often they’d stop and ask an expert type exactly how much power the cyclists had generated across the course of the day so far. Mr Expert would respond with a number of kilowatt hours (kwh). Now, I have a Physics A-level from not too long ago and I’ll admitt that even for me the concept of a kwh was a fuzzy memory rather than a clear understanding of quite what energy the family was using.

So rightly, the BBC decides it should convert this rather abstract kwh into something more solid that the viewers at home could relate to. And what did they pick? Something simple but still measurable and scientific that everyone can relate to, like number of 100watt lightbulbs running for an day? No actually, it wasn’t. They went for that well known unit of engery, the digestive biscuit.

Let me just repeat that: digestive biscuit. How in the name of all that is science does one get from kwh (the multiplication of power in watts and time in hours) to digestive biscuits (the multiplication of flour, sugar vegetable oil)? It… what? How many digestive biscuits does it take to cook a chicken? Operate lift? Burn down McVities? It just doesn’t work.

OK, let’s say we’re comparing the kwh to the energy contained within each individual biscuit. Fine. First, can I have some information on mass and composition of the biscuit, please? Then would that be the energy in joules? In calories? The energy dissipated from me jumping up and down on a 20-piece packet until each sorry biscuit is a pile of crumbs so dense it will soon be designated anti-matter? Which?

I remember watching an episode of the children’s afternoon news slot, Newsround, where they compared the height of a building to that of so many Tyrannosaurus rexes, and wondering how on earth I was meant to know how tall a T. Rex was. But at least they were comparable units!

Converting kilowatt hours into digestive biscuits is like taking a length, and conveying it in terms of forrest.* It’s not adapting to an audience BBC, it’s just nonsense.

*That is, the distance covered by [x] sheets of A4 paper, laid end-to-end portrait orientation, where [x] is the number of A4 sheets that can be manufactured from a forest containing an indeterminate number of trees of unspecified height. Try using it next time someone asks how far to the bus stop. I’m sure they’ll understand.