Tag Archives: stars

Energy transformations

I mentioned a couple of weeks ago that I am teaching thermodynamics at the moment [see ‘Conversations about engineering over dinner and a haircut‘ on February 16th, 2022].  I am using a blended approach [see ‘ Blended learning environments‘ on November 14th, 2018] to deliver the module to more than 300 first year undergraduate students with one hour in the lecture theatre each week while the students follow the components of the MOOC I developed some years ago [see ‘Free: Energy! Thermodynamics in Everyday Life‘ on November 11th, 2015, and ‘Engaging learners online‘ on May 25th, 2016].  I have found that first year undergraduates are reluctant to participate in the online discussions that are part of the MOOC and so last year I asked them to discuss each topic in small groups with their academic tutor.  I got some very positive feedback from tutors who had interesting and stimulating discussions with their students.  We are repeating the process again this year.  The first discussion is about energy transformations: noting that energy is always conserved but constantly transformed into different forms, each student is asked to start from an energy state of their choice and to trace the transformations backwards until they can go no further.  In the lecture preceding the discussion with their tutor I provide some examples for starting states, including breakfast cereal, a pole vaulter in mid-jump and a bullet train.  I also describe the series of transformations from the Big Bang to tectonic plate movement: after the initial expansion caused by the Big Bang, the universe cooled sufficiently to allow the formation of sub-atomic particles followed by atoms of hydrogen and some helium and lithium that gravity caused to coalesce into clouds which became the early stars, or solar nebula.  A crust formed on the solar nebula which broke away to form planets.  Our planet has a molten core with temperatures varying from 4,400 to 6000 degrees Celsius, compared to around 5,500 degrees on the surface of the sun.  The temperature variation in the Earth’s core cause thermal currents which drive the movement of tectonic plates and so on [see ‘The hills are shadows, and they flow from form to form, and nothing stands‘, on February 9th, 2022].  Most chains of energy transformation lead backwards to the sun and forwards to dissipation of energy into some unusable form which we might call ‘entropy’ [see ‘Life-time battle‘ on January 30th, 2013].

Limits of imagination

What’s it like being a bat?  ‘Seeing’ the world through your ears, or at least a sophisticated echo-location system. Or, what’s it like being an octopus?  With eight semi-autonomous arms that I wrote about a couple of weeks ago [see ‘Intelligent aliens?’ on January 16th, 2019]. For most of us, it’s unimaginable. Perhaps, because we are not bats or octopuses, but that seems to be dodging the issue.  Is it a consequence of our education and how we have been taught to think about science?  Most scientists have been taught to express their knowledge from a third person perspective that omits the personal point of view, i.e. our experience of science.  The philosopher, Julian Baggini has questioned the reason for this mode of expression: is it that we haven’t devised a framework for understanding the world scientifically that captures the first and third person points of view; is it that the mind will always elude scientific explanation; or is that the mind simply isn’t part of the physical world?

Our minds have as many neurons as there are stars in the galaxy, i.e. about a hundred billion, which is sufficient to create complex processes within us that we are never likely to understand or predict.  In this context, Carlo Rovelli has suggested that the ideas and images that we have of ourselves are much cruder and sketchier than the detailed complexity of what is happening within us.  So, if we struggle to describe our own consciousness, then perhaps it is not surprising that we cannot express what it is like to be a bat or an octopus.  Instead we resort to third person descriptions and justify it as being in the interests of objectivity.  But, does your imagination stretch to how much greater our understanding would be if we did know what is like to be a bat or an octopus?  And, how that might change our attitude to the ecosystem?

BTW:  I would answer yes, yes and maybe to Baggini’s three questions, although I remain open-minded on all of them.


Baggini J, The pig that wants to be eaten and 99 other thought experiments, London: Granta Publications, 2008.

Rovelli C, Seven brief lessons on physics, London, Penguin Books. 2016.

Image: https://www.nps.gov/chis/learn/nature/townsends-bats.htm