{ "cells": [ { "cell_type": "markdown", "id": "a87ee9f6-faac-48c1-91c3-148016b72ae7", "metadata": { "tags": [] }, "source": [ "# Introduction to Thermodynamics and Statistical Physics" ] }, { "cell_type": "markdown", "id": "fad3d3d7-27cd-4c1b-9527-ce3bcc589030", "metadata": {}, "source": [ "In this lecture, we are going to continue introducing some topics which are needed to fully explore thermal physics. In particular, we'll cover:\n", "\n", "* Thermal Equilibrium and the Zeroth Law of Thermodynamics\n", "* Thermometers\n", "* Microstates versus macrostates\n", "* Temperature\n", "* Ensembles\n", "* Boltzmann distribution" ] }, { "cell_type": "markdown", "id": "d8059623-68a7-49a1-81c9-d022a7097d7d", "metadata": { "tags": [] }, "source": [ "## Thermal equilibrium" ] }, { "cell_type": "markdown", "id": "bd54e72c-3c28-4804-94ef-fe5544fdaf52", "metadata": {}, "source": [ "What exactly is temperature? Qualitatively, it is how hot or cold an object is, but this is of course subjective. If we have two bodies, and we know that one with temperature $T_1$ is hotter than one with temperature $T_2$, then we know that $T_1>T_2$.\n", "\n", "![Thermal Equilibrium](Figures/Thermal_Equilibrium.png)\n", "\n", "Furthermore, we know that if we bring two bodies into thermal contact with each other, heating (energy in transit) will occur between bodies (shown in b above), and they'll eventually end up with a temperture $T_1>T_{\\rm f}>T_2$ (c). When this is achieved, and there is no net flow between the bodies, they are in **thermal equilibrium**.\n", "\n", "This process is not reversible. That is, if we have two objects in thermal contact, and they are in thermal equilibrium, we would never expect them to spontaneously to undergo a flow of energy that goes from (c) back to (a). So, this means as a function of time, bodies tend towards thermal equilibrium.\n", "\n", "Realising this, and also then that if multiple bodies are in thermal equilibrium with each other, then all bodies must be at the same tempearture leads us to the Zeroth law of thermodynamics." ] }, { "cell_type": "markdown", "id": "197631ee-b313-460f-b470-39b36a40ad2a", "metadata": {}, "source": [ "