Tag Archives: time

We inhabit time as fish live in water

A couple of weeks ago (‘Only the name of the airport changes’ on June 12th, 2019) I wrote about the stretching and compression of time while I waited for my much delayed flight to Reno. I mentioned Aristotle’s view of time as the measurement of change; however, Newton believed that time passes even when nothing changes. Einstein resolved the conundrum, represented by these different views, using the concept of a space-time domain forming a gravitational field containing waves. My title is a quote from Carlo Rovelli’s book, ‘The Order of Time‘. And, according to Rovelli, ‘mass slows down time around itself’, which I think will cause waves in the space-time domain .  Conservation of energy implies that the movement of an object will tend towards space where time passes more slowly, i.e. in the vicinity of large masses. Hence, things fall downwards because time runs more slowly close to the Earth. This implies that time passes more slowly at the airport than on the plane in flight; but, of course, the differences are too small for us to measure or perceive.

Image: Art work ‘Gaia’ by Luke Jerram in Liverpool Cathedral

Source:

Carlo Rovelli, The Order of Time, Penguin, 2019.

Only the name of the airport changes

The conference that I attended last week was in Reno, Nevada and, on my way to it, I stopped over in Dayton, Ohio and visited the US Air Force Research Laboratory to present the results from our research project supported by their European Office of Aerospace Research & Development (EOARD).  The journey from Liverpool to Dayton, via Manchester and Altanta airports, took 17 hours; however, that was short compared to the journey from Dayton to Reno, via Chicago and San Francisco airports, which took 24 hours door-to-door or rather hotel-to-hotel.  ‘Only the name of the airport changes’ is a quote from Italo Calvino describing the city of Trude in his book ‘Invisible Cities‘; but it also described how I felt looking out from my window seats at successive airports over the four days that I travelled from Liverpool to Reno.

We arrived at Dayton airport at 5am for a 7am flight to be told that it was cancelled and we were re-booked on a flight leaving at 5.18pm.  We tried to re-rent the rental car that we had just returned but were told every car was booked; so, we were stuck in Dayton airport for 12 hours.  Your perspective of time changes in these circumstances.  At 5am with nothing much to do, 12 hours seemed like infinity; but at 5pm when we were about to board our flight, the same 12 hours seemed short – almost as if we had only arrived at the airport an hour or so earlier.  Augustine observed that our consciousness is based on memory and anticipation such that time is entirely present in our minds as memory and as anticipation.  While Aristotle considered time to be the measurement of change.  Hence, since I was anticipating no change during my 12 hours of waiting, my perception of time was of it passing very slowly.  Whereas, when I was boarding my flight 12 hours later, my memory was of having done the same things that I would usually have done while waiting for a flight [reading and editing draft manuscripts from my research group]; and hence my perception of the elapsed 12 hours was compressed into the usual 2-hour period spent at an airport prior to a flight.  The apparent unchanging view out of the plane’s window, both in flight and, to a lesser extent, on the ground also tended to distort my perception of the passage of time.

Sources:

Italo Calvino, Invisible Cities, Penguin Vintage Classics, 1997.

Carlo Rovelli, The Order of Time, Penguin, 2019.

 

Is there a real ‘you’ or ‘I’?

I have written recently about time and consciousness [see ‘Time at the heart of our problems‘ on January 30th, 2019 and ‘Limits of imagination‘ on February 13th, 2019].  We perceive some things as almost constant or changeless, such as trees and landscapes; however, that is just a consequence of our perception of time.  Nothing that is in equilibrium, and hence unchanging, can be alive.  The laws of thermodynamics tell us that disequilibrium is fundamental in driving all processes including life.  Our perception of experience arises from registering changes in the flow of sensory information to our brains and as well as changes in the networks of neurons in our brains.  Hence, both time and complexity appear to be essential ingredients for consciousness. Even when we sit motionless watching an apparently unchanging scene, as a consequence of the endless motion of connections and signals in our brains, our minds are teeming with activity, churning through great jumbles of ideas, memories and thoughts.  Next time you are sitting quietly, try to find ‘you’; not the things that you do or experience but the elusive ‘I’.  We assume that the elusive ‘I’ is there, but most of us find nothing when we look for it.  Julian Baggini has suggested that the “I” is ‘a nothing, contentless centre around which experiences flutter like butterflies.’

Sources:

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

Czerski H, Storm in a teacup:the physics of everyday life, London: Penguin Random House, 2016.

Godfrey-Smith P, Other minds: the octopus and the evolution of intelligent life, London: William Collins, 2018.

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

Time at the heart of our problems

This week I started teaching thermodynamics to first year undergraduate students for the first time in twelve months.  I have had a break for a year because my course, which is only delivered once per year, was moved from first to second semester.  Although I have continued to teach postgraduate courses, it’s been like a sabbatical enforced by timetable changes.  Sadly, it’s over and I am back in the large lecture theatre in front of a couple of hundred of students – that makes it sound as if I don’t enjoy it which is not true but it does increase the intensity of the job because all of the other aspects of the role continue unabated.  So, for me time appears to accelerate as I attempt to jam more activities into a week.

Time lies at the heart of much of thermodynamics although we tend not to deal with it explicitly; however, it is implicit in our use of changes in the state of a system to understand it.  Quote Anaximander, the pre-Socratic philosopher & pupil of Thales of Miletus: ‘We understand the world by studying change, not by studying things’.  Time also lies at the centre of the tangle of problems found at the intersection of the theories of gravity, quantum mechanics and thermodynamics.  As Carlo Rovelli has remarked we are still in the dark about this tangle of problems; so, I will touch on it in my thermodynamics course but just to show students the limits of our knowledge and perhaps inspire one or two of them to think about tackling them in postgraduate studies.

Meanwhile, I plan tackle my challenges with time by slowing it down once a week with a walk in the Clwydian Hills where the landscape appears unchanging so that time stands still allowing me to relax.

Sources:

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

Wohllerben P, The hidden life of trees, London, William Collins, 2017.