# Reversible temperature exchange upon thermal contact

## TL;DR

This paper introduces a novel reversible temperature exchange method where two bodies with arbitrary temperature differences can fully swap their temperatures through sequential contact of infinitesimal parts, expanding thermodynamic principles.

## Contribution

It reveals an alternative reversible heat exchange process using infinitesimal parts, extending classical thermodynamics beyond infinitesimal temperature differences.

## Key findings

- Complete temperature exchange is possible with finite temperature differences.
- Sequential contact of infinitesimal parts achieves reversibility.
- The method broadens understanding of reversible processes in thermodynamics.

## Abstract

According to a well-known principle of thermodynamics, the transfer of heat between two bodies is reversible when their temperatures are infinitesimally close. As we demonstrate, a little-known alternative exists: two bodies with temperatures different by an arbitrary amount can completely exchange their temperatures in a reversible way if split into infinitesimal parts that are brought into thermal contact sequentially.