>Just a nitpick, but there’s no such thing as cold (only the relative lack of heat).
Just another nitpick - cold and heat are concepts that have had names for millenia, and whether they are “things” depends on your intended use of the word “thing”. In the technical definition of “heat”, it is thermal energy that is being transferred from one place to another, so there is little heat involved in a Thermos bottle full of hot coffee, at least not until you pour some out. One could argue from that point of view that in the above discussion “cold” is more a thing than “heat” is. While people more often calculate with higher temperatures associated with positive energy values, in all practical situations there is a symmetry between heat and cold as traditionally defined, except that you can’t get temperatures below some lower limit (0 K) - and I usually go years between situations where that lower limit matters. As far as I know, and I’m a physicist who’s been concentrating on heat transfer and thermal technology for the last several years, you can’t say cold is any less a thing than heat is.