Carlo Rovelli, Order of Time, time and events Rovelli says that "the fundamental equations do not include a time variable".
Further, the world is made of events.
It seems to me that events are intrinsically temporal. A kiss has a duration. How can he reconcile this?
 A: All he is saying is that the laws of physics are not explicitly time dependent. For example, the relationship $E=mc^2$ does not vary with $t$.
A: I have not read the book you are citing, but I note the use of the phrase 'the fundamental equations'. I think he must be referring to various equations that make up the way physics at the level of space, time and basic constituents of the cosmos is currently formulated. Such equations are 'fundamental' in certain respects, but not in others. For example, they do not constitute the correct description in full, because we do not know what that correct description is. There are many unknowns in physics. He appears to be advancing the hypothesis that the entire story of the cosmos is based on time-reversible basic processes. This is widely thought to be so because quantum mechanics seems to suggest it, but it is not known and there is evidence in the other direction. For example, one of the counter-arguments comes from the physics of black holes and Hawking radiation (the black hole information paradox). Another comes from the long-standing debate over exactly how the maths of quantum physics connects to the story of the physical events themselves (the quantum measurement problem). Another comes from the sensitivity of processes to initial conditions, and the fact that infinitely precise real numbers are a mathematical idealization and it is not clear whether this idealization captures the nature of the physical world precisely, or is just a useful idealization.
So the main aim of this answer is to say that your question goes to what is the nature of the physical world, whether it genuinely develops in new ways or whether its future is encoded in its present. The main aim of my answer is to point out that when people assert with confidence that they 'know' the nature of the physical world to be such that time is like a parameter rather than allowing development of genuine novelty, they do not in fact know this to be true. It is just an interpretive posture, one that downplays the counter-evidence.
I would say that your example of a kiss is a perfectly apt example of something that does indeed happen and gets the status of 'event'; something that can be recognized and whose meaning can be discussed.   Our knowledge of physics is very far from being able to support the conclusion that the decision of two specific people to share a kiss is somehow encoded into the parameters of the universe at the time of the Big Bang.
A: I cannot find the exact words that you quote in Rovelli's book, but a similar phrase occurs near the beginning of Chapter 6 "The World is Made of Events not Things". Here is the paragraph in full:

The absence of the quantity 'time' in the fundamental equations does not imply a world that is frozen and immobile. On the contrary, it implies a world in which change is ubiquitous, without being order by Father Time; without innumerable events being necessarily distributed in good order, or along the single Newtonian timeline or according to Einstein's elegant geometry. The events of the world do not form an orderly queue, like the English. They crowd around chaotically, like the Italians.

Rovelli agrees that events have duration. What he disagrees with is the idea that events occur in a fixed sequence - instead, he sees them as forming a complex network. In mathematical terms, this is the difference between a total order and a partial order.
At this point Rovelli has spent the first five chapters of the book showing that our intuitive notion of time as a continuous and independent background to everything in the universe is flawed, and has been demolished successively by thermodynamics, general relativity and quantum mechanics. Later on, in Chapter 8 "Dynamics as Relation" he says

The fundamental equations of quantum gravity are effectively formulated like this: they do not have a time variable, and they describe the world by indicating the possible relations between variable quantities.

When he says "quantum gravity" he means the particular version of loop quantum gravity on which he works. This is one of several possible candidates for a theory of quantum gravity, and it has not yet been experimental verified (or disproved).
A: There are to ways to look at it:

*

*Hypothesis 1 :

One approach assumes that time is a "thing" per se; a sort of linear dimension, like the 3 dimensions of classical space and that events happen as a function of said parameter.

*

*Hypothesis 2 :

Another approach assumes that events "just happens" in a given sequence (which we call causality). Under that second hypothesis, time is not a "thing", merely a "currency" or conversion factor, a way to compare the frequency of cyclical phenomena (non-dissipative) to the frequency of another one (the cycle of the days compared to the cycles of the moon for instance (days and months, basically)). Also, the same concept can be used to measure the relative value of dissipative phenomenon compared to cyclical phenomenons in terms of cycles or sub-cycles, etc. (for example, the average human being lives for about 70 years, roughly 700 moon cycles, whereas the average dog will live 7 years (roughly 70 moon cycles, hence a factor of 10)).
Under the second hypothesis, time is not a "thing", not a physical primitive value, but a derived value sometimes called "emergent".
In that sense, it is not real (in the sense: not fundamental); it is just a convenient parameter that can be used to describe, parametrise, the evolution of a dissipative system (in terms of cycles of a non-dissipative system).
Under the second hypothesis, it is not the entropy of an isolated system that grows with time; it is the evolution (in a succession of causal events) of an isolated system that translates into a progressive increase of entropy, which in turn yields the illusion that the system's evolution is driven by the passing of time.
The second approach makes more sense than the first one, because it accounts for the facts that:

*

*Fondamental physical equations are time-reversible (no microscopic arrow of time).


*Time is not a dimension like space.
A: I don't know if and where Rovelli made such a statement, but this statement is wrong because there are fundamental time processes:
The cosmologic process of space expansion is time dependent. And there is also a microcosmic fundamental time-dependent equation which is a bit less common: The spin of mass particles is a physical process which is time dependent, that means, the "revolution" of one spin takes a certain time, and we could define the age of a particle by counting the number of "revolutions" of its spin.
A: I was wondering about this myself too! I think he just means that the whole of spacetime (including all events and wordlines) is a static entity. This entity is called the block universe, as you've probably heard of. The passage of time is an illusion in this view of the universe. It doesn't exist in reality. Past, present, and future exist all at the same, well..., time. In the growing half-block universe only the past and present coexist at the same time, while the future is not (yet) part of this whole.
So, while time and space exist in this view, the passage of time does not.
Because this block universe doesn't change, no time variable is needed to describe it. There simply is no time variable. Only instant times exist.
