Rosanvallon, Jérôme <br/><br/>
Timeless Variation: A Contribution to the Metaphysics of Quantum Gravity (2/2) 

 -  2022.<br/>							 
<br/><br/> 82 
<br/><br/> “Scientific inventions and revolutions, while they have not always initiated metaphysical inventions and revolutions likely to echo them, have at least prompted them. Modern physics has experienced many such revolutions over the past century. The turn of the XXth century saw the arrival of special and general relativity as well as quantum mechanics. More recently, there has been the development of an adequate quantum theory of gravitation, which has yet to be finalized and validated. These scientific revolutions have in turn laid the groundwork for a metaphysical revolution concerning the nature of time, a complex concept that these theories have helped to clarify, by distinguishing time’s many layers and entangled aspects. As a result, every quantum theory of gravitation (notably that of loop quantum gravity) only seems to succeed by considering time as a secondary, derived reality, not a constitutive or fundamental one. But upon what other more fundamental reality could time be based? Could that reality itself be unchanging in any way? Aren’t we wrong to confuse time and variation (or change) in this way? The purpose of this article is to carefully distinguish between these two concepts by showing, on the one hand, that variation is actually – under certain theoretical conditions yet to be stated – a more fundamental concept than that of time. On the other hand, the article will demonstrate that time can be based on a variation, envisioned as non-empirical or pure, and that by adding a given set of constraints to it, the variation becomes empirical and endowed with the main constituent properties of time. In our view, there seem to be three kinds of these constraints or restrictive conditions: subsistence (or invariance), continuity, and succession. We will expand on them in turn by showing how special and general relativity and quantum physics already tend to partially violate these constraints. As a result, we conclude that variation must fundamentally be considered as the variation of nothing in particular whereas time is always in reality the time of something.”