Carlo Rovelli on the direction of time, #heat

heating art nouveau house rue de l'hippodrome 1015.JPG(Man demonstrating heating system, art nouveau house, Brussels, 2015)

The difference between past and future only exists where there is heat. The fundamental phenomenon that distinguishes the future from the past is the fact that heat passes from things that are hotter to things that are colder. (Carlo Rovelli, Seven brief lessons on physics, 2014 tr. 2015)

Published by

Paul Hodson

Head of Unit "EnergyEfficiency" at European Commission, Directorate-General for Energy

One thought on “Carlo Rovelli on the direction of time, #heat”

  1. I think that professor Rovelli’s theory about heat is quite interesting, especially when we look at it from the perspective of Heraclitus, the old Greek philosopher that teached that fire, i.e. heat or energy, is the material principle of the universe. First of all fire can not be called properly a state of matter, as solid, liquid or gaseous, but rather a process, which necessarily involves time. So, the direction of time, the irreversibility of time, or the arrow of time as A. Eddington happily named it, can be stated in a very simple way: initially fire lights, ignites, or simply burns and this is precisely how we can recognize it as a fire, and only afterwords, when its fuel is exhausted, fire is extinguished or quenched. So the difference between past and future is the same as that between an ignited fire and a quenched one (which of course are the same, but at different moments of time). It would be quite a surprise for any of us that a bonfire started form the ashes, that then it turned to fire and finally to find untouched the dry wood previously burned. As I think Einstein said once, maybe in a thousand years more physical science will be very different form ours, but thermodynamics, the laws of fire and heat, will surely be the same: fire will go on, burning first and quenching after, showing us the eternal direction of time, from the past to the future…

    Best regards, J. P. Gómez


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