Author Archives: Eann Patterson

Intelligent openness

Photo credit: Tom

As an engineer and an academic, my opinion as an expert is sought often informally but less frequently formally, perhaps because I am reluctant to offer the certainty and precision that is so often expected of experts and instead I tend to highlight the options and uncertainties [see ‘Forecasts and chimpanzees throwing darts’ on September 2nd 2020].  These options and uncertainties will likely change as more information and knowledge becomes available.  An expert, who changes their mind and cannot offer certainty and precision, tends not to be welcomed by society, and in particular the media, who want simple statements and explanations.  One problem with offering certainty and precision as an expert is that it might appear you are part of a technocratic subset seeking to impose their values on the rest of society, as Mary O’Brien has argued.  The philosopher Douglas Walton has suggested that it is improper for experts to proffer their opinion when there is a naked assertion that the expert’s identity warrants acceptance of their opinion or argument.  Both O’Brien and Walton have argued that expert authority is legitimate only when it can be challenged, which is akin to Popper’s approach to the falsification of scientific theories – if it is not refutable then it is not science.  An expert’s authority should be acceptable only when it can be challenged and Onora O’Neill has argued that trustworthiness requires intelligent openness.  Intelligent openness means that the information being used by the expert is accessible and useable; the expert’s decision or argument is understandable (clearly explained in plain language) and assessable by someone with the time, expertise and access to the detail so that they can attempt to refute the expert’s statements.  In other words, experts need to be  transparent and science needs to be an open enterprise.


Burgman MA, Trusting judgements: how to get the best out of experts, Cambridge: Cambridge University Press, 2016.

Harford T, How to make the world add up: 10 rules for thinking differently about numbers, London: Bridge Street Press, 2020.

O’Brien M, Making better environmental decisions: an alternative to risk assessment, Cambridge MA: MIT Press, 2000.

Walton D, Appeal to expert opinion: arguments from authority, University Park PA: Pennsylvania State University Press, 1997.

Royal Society, Science as an open enterprise, 2012:

Walking the hills

daffodils at moel famauA regular reader of this blog commented last week on the enjoyment she gained during the pandemic from their daily walk around a local lake which reminded me about a recent experience on one of our regular weekend hikes around Moel Famau, which have been real rather than virtual for some months now [see ‘Virtual ascent of Moel Famau‘ on April 8th, 2020].  It was an unseasonally warm day and there was a strong scent from the daffodils in the broad verge next to the farm track that we were walking down.  The impact of the scent on my sense of well-being was almost like a form of synaesthesia [see ‘Engineering synaesthesia‘ on September 21st, 2016].  I am on vacation this week, hoping to slow down [see ‘Slow down, breathe your own air‘ on December 23rd 2015], climb some hills and feed my consciousness some different sensory experiences [see ‘Feed your consciousness with sensory experiences‘ on May 22nd 2019].

Dwelling in the present

Photograph of St Michael's Church, Stoke Gifford

St Michael’s Church, Stoke Gifford

I have been visiting the Airbus site at Filton near Bristol since the mid-1990s. It is where the wings for new designs of aircraft are developed and tested. My involvement has been in the developing of techniques for measuring strain in aircraft structures during static and fatigue tests. At the moment, we are working on methods to integrate fields of measurements with computational predictions of stress and strain [see ‘Jigsaw puzzling without a picture‘ on October 27th, 2021]. I frequently travel by train to Bristol Parkway Station and walk past the church in the photograph without even noticing it despite it being next to the station. To be fair, the view of it from the station entrance is obscured by a billboard. However, last week as I walked back to the station with a half-hour to spare, I noticed a gate leading into a churchyard. I slipped through the gate thinking that perhaps there might be an interesting old church to explore but it was locked and I had to be satisfied with a stroll around the churchyard. I was slightly shocked to realise the church, and the village green beyond it, had been hidden in full view for more than thirty years of walking within a few tens of metres of it perhaps once a month. I had always been too focussed on the research that I was heading to Airbus to discuss, or too tired at the end of a day, to notice the things around me. Our senses flood our brains with information most of which is ignored by our conscious minds that are busy time traveling through past memories or looking into the future [see ‘Time travel and writing history‘ on March 23rd, 2022].  However, there is pleasure to be gained by dwelling in the present and exploring the sensory experience flooding into our brains.  As Amy Liptrot commented in her book ‘The Outrun‘, “the more I take the time to look at things, the more rewards and complexity I find”.


Enuma Okoro, The Pleasure Principle, FT Weekend, 19 February/20 February 2022.

Mia Levitan, Descent into digital distraction, FT Weekend, 5 March/6 March 2022.


From nozzles and diffusers to stars and stripes

Schematic diagram of explanation in textAt the end of a lecture on energy flows in my first year undergraduate course on thermodynamics, I talk about nozzles and diffusers as examples of practical applications of the rest of the material in the lecture.  It is hazardous to sit in the front row of the lecture theatre because I take in a water bottle with a trigger spray to demonstrate how the nozzle increases the velocity of the fluid at the expense of pressure while gently sprinkling water on the front row.  I am always intrigued by the symmetry of nozzles and diffusers.  Diffusers increase pressure of a fluid at the expense of its velocity, i.e., a mirror image of the action of a nozzle.  The cross-sections are also mirror images because a nozzle has a cross-section that decreases in the flow direction while a diffuser has a cross-section that increases in the flow direction.  At least for sub-sonic flows, because the shapes are reversed for super-sonic flow; so a sub-sonic nozzle looks like a super-sonic diffuser and a sub-sonic diffuser looks like a super-sonic nozzle.  If that all sounds like fluid mechanics then the thermodynamic message is that, in nozzles and diffusers, the rates of heat and work transfer are approximately zero while the change in the kinetic energy of the fluid is very large.  I finish the lecture with a video clip of a school quartet of trombones playing ‘Stars and Stripes Forever’ which wakes up the students who have slept through the lecture and allows me to point out the diffusers (bell of the trombone) transmitting acoustic pressure.

You can watch the video clip on YouTube at