# 2024 ‘Key Reflections’ on Sadi Carnot’s 1824 ‘Réflexions’ and 200 Year Legacy

## TL;DR

This paper reflects on Sadi Carnot's 1824 work and its lasting impact on thermodynamics, highlighting his role as a foundational figure.

## Contribution

The paper provides novel logical reflections and generalizations on Carnot's reasoning, emphasizing his influence on thermodynamics.

## Key findings

- Sadi Carnot's work is re-evaluated as a foundational contribution to thermodynamics.
- Carnot's reasoning is linked to later concepts like conservation of energy.
- The paper highlights Carnot's role as a 'forefather' of thermodynamics.

## Abstract

This author is not a philosopher nor a historian of science, but an engineering thermodynamicist. In that regard, and in addition to various philosophical “why and how” treatises and existing historical analyses, the physical and logical “what it is” reflections, as sequential Key Points, where a key Sadi Carnot reasoning infers the next one, along with novel contributions and original generalizations, are presented. We need to keep in mind that in Sadi Carnot’s time (early 1800s), steam engines were inefficient (below 5%, so the heat in and out was comparable within experimental uncertainty, as if caloric were conserved), the conservation of caloric flourished (might be a fortunate misconception leading to the critical analogy with the waterwheel), and many critical thermal concepts, including the conservation of energy (The First Law), were not even established. If Clausius and Kelvin earned the title “Fathers of thermodynamics”, then Sadi Carnot was ‘the ingenious’ “Forefather of thermodynamics-to-become”.