Here is a slightly more sophisticated lab demonstration of the reality of absolute zero.
https://www.youtube.com/watch?v=psKupK6E-Sc How much of modern physics depends on the presumed reality of absolute zero? Harry On Mon, Nov 16, 2020 at 11:43 AM H LV <hveeder...@gmail.com> wrote: > Here is a classroom demonstration of how to estimate absolute zero. > > Charles Law and absolute zero. > https://www.youtube.com/watch?v=wkWo-8tY8cY > > Btw, if the temperatures and volumes of other gases are measured and > plotted you will get lines with different slopes, but they will all > converge on the same value of absolute zero. However, this is based on a > _extrapolation_. Maybe the volume of a gas and its temperature don't > maintain this linear relationship as the volume approaches zero. William > Thomson (Lord Kelvin) first proposed that this linear extrapolation was > reliable. The demonstrator quotes him at about seven minutes into the > video: > > << ...infinite cold must correspond to a finite number of degrees of the > air-thermometer below zero; if we push the strict principle of graduation, > stated above, sufficiently far, we should arrive at a point corresponding > to the volume of air being reduced to nothing, which would be marked as > -273° of the scale (-100/.366, if .366 be the coefficient of expansion); > and therefore -273° of the air-thermometer is a point which cannot be > reached at any finite temperature, however low. >> footnote 6 from > https://zapatopi.net/kelvin/papers/on_an_absolute_thermometric_scale.html > > I think it is illogical to propose a linear relationship exists all the > way down to absolute zero. Air with no volume is an oxymoron. Linearity > may be an excellent approximation over most scales, but I would say > below some small but finite volume the linear assumption breaks down with > or without appeals to quantum mechanics. > Harry >
