Kyla Stephan who writes the marvellous Library Ghost blog knitted me a hat for today’s Science March in Brisbane.
There are rightly some questions to be asked about the march organisers’ approach to diversity and inclusion, but I also thought it was important to show up and be counted in the name of all people who are curious about the world and revise their beliefs in the face of evidence.
In return for my hat, I had to find Kyla an interesting science story.
So here are a few words about drug dosage and cheesy moonshots.
What are the physics of highly compressed cheese and why does it matter?
My favourite science show-off moment was at a conference on Science and Storytelling at the University of Cardiff some years ago.
I was interested in how medics and health workers used storytelling in science, and one of my favourite projects was by an information scientist called Harold Thimbleby (PDF download).
He pointed out that in Europe, about 120,000 hospital deaths per year are caused by drug calculation errors – that’s more people than die in car accidents.
Not all of those errors can be blamed on the staff, however. The automatic pumps which dispense drugs through IVs etc are often difficult to program, and although they look like calculators, they are not.
An example:
A “simple” drug calculation is: how many mL/hr should an infusion pump be set to in order to give a patient 5250mg of fluorouracil over 4 days at a concentration of 45.57 mg/mL?
The simplest correct calculation using a basic calculator is: [AC][MRC][MRC]4 × 24 [MPLUS][AC]5250 ÷ 45.57 ÷[MRC] =
After getting all those key presses right, you then have to go through another round of button presses on the pump, without making any mistakes. All as just one task in your busy day at the hospital.
Professor Thimbleby developed a prototype smartphone app which asked you what the drug calculation was, and the type of pump you were using, and then guided you through the key presses step by step.
This reduced human error and created opportunities for the user to check and double check throughout the process.
What has all that got to do with a moon made of cheese?
Almost offhandedly, during his talk, Professor Thimbleby spoke of the certainty with which we know the moon isn’t made of cheese. He compared this scientific certainty to the world of storytelling, where we can still indulge that fantasy.
Even without visiting the moon, we can tell it isn’t made of cheese because of its albedo – the fraction of solar energy which it reflects back into space.
Different materials have different reflectivity: for example, ice and snow have a high albedo and cause most of the sunlight hitting them to reflect back into space.
We can work out the albedo of cheese and observe the brightness of the moon to confirm that it is, sadly, not made from dairy products.
But – but but but – what if the moon were made of cheese? How could we indulge that fantasy while maintaining the rigour of critical and scientific thinking?
Do we need to imagine a cheese-moon which is the same size or the same mass?
If the latter, the moon would have to be a lot larger. Nocturnal animals and the science of astronomy would be affected by the larger moon in our sky, with its much higher albedo.
What’s more, a moon sized piece of cheese would be denser and hotter at its centre owing to gravitational compression.
Would there be volcanos of molten cheese? At extreme high pressures, does cheese maintain its integrity, or break down into its component parts? Would the massive internal pressure cause it to explode?
I love that scientists can begin to explore these hypothetical situations without even having to leave the comfort of their armchair – or in our case, the post-march pub.
I love that there is a happy borderland where science and science fiction meet, and valuably so – because they are, ultimately, both spaces of wonder.
Professor Thimbleby made his cheesy digression and showed the value of thinking carefully and critically, reasoning from available evidence – but his work also demonstrates that you could save lives just by paying close attention to technology and human interaction.
He didn’t need to be in the ward to come up with a way to avoid deaths from drug miscalculation, and he didn’t need to land on the moon to work out what it was made of.
How cool is that? Read more →
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