I gets weary, and sick of trying … the words almost taken from Ol' Man River.  But weary of what?  Trying to persuade the physics world from harping too much on about celebrity physicists.  This they do (at least in my reading) to an extent grossly exceeding that of mathematicians and chemists.  “How will we discover the African Einstein?” they ask, to which I reply that a wilderness of Einsteins would do Africa no good at all, whereas a widespread knowledge of basic physics might help the continent somewhat.  Even if Mariah Carey’s new album E=MC² inspires some to take up physics, most will fall exhausted before reaching such high levels.

But lo!  A refreshing paper has come my way – Gadflies and Geniuses in the History of Gas Theory by Stephen G. Brush of the University of Maryland [1].  Being inspired by the Principle of Least Action,  I will save effort by first quoting chunks of the abstract:

The history of science has often been presented as a story of the achievements of geniuses: Galileo, Newton, Maxwell, Darwin, Einstein …. In this article I consider a different type of story …. progress stimulated by gadflies – outspoken critics who challenge the ideas of geniuses, forcing them to revise and improve those ideas, resulting in new knowledge for which the genius gets the credit while the gadfly is forgotten.

Carl Wieman in his recent blog stated:

Another striking example of inefficiency of the current system is the way in which the same science topics are covered repeatedly in the curriculum for a science major, but each time covered so rapidly and taught so ineffectively that students do not achieve mastery.

Gas theory is one area where my own experience of not achieving mastery after repeated goes bears that out.  And yet it is such a beautiful subject!  So, back to the main article:

Towards the end Brush deals with the struggles Boltzmann had with his critics over the concept of reversibility.  In the latter half of the 19th century, the Second Law of Thermodynamics seemed to indicate that the Universe would suffer a “Heat Death”, as it reached maximum entropy.  This is closely tied in with the concept of Reversibility, and today the concept is still as clear as mud, only we know a lot more about the mud.  As the link just above starts:

A certain professor of thermodynamics was known to give the same final exam every year, always consisting of just the single question:  “What is entropy?”  One day an assistant suggested that it might be better to ask a different question now and then, so the students wouldn’t know in advance what they would be asked.  The professor said not to worry.  “It’s always the same question, but every year I change the answer.”

Now, like the Bear after the Last Battle, I will move on to something I do understand.

James Clerk Maxwell and Ludwig Boltzmann were the first to produce a coherent statistical theory of the distribution of energy in a system.  Maxwell had already produced a good version, but Francis Guthrie seemed to throw a spanner in the works by suggesting that air molecules should lose kinetic energy simply by being further up in the atmosphere, so that the temperature ought, on that account, to drop as one goes higher.  What price then thermal equilibrium and the implied uniform temperature? In even turns out that Guthrie’s calculation would make that happen even more quickly that it actually does!  But Maxwell, and independently Boltzmann, came up with a much more profound theory that ‘rescues’ thermal equilibrium, and does a lot more.  How I understand, then, the cooling of the air as one climbs a mountain is that it is due to a ‘bicycle pump’ effect, whereby falling air gets compressed and warmer, and vice-versa.

In 1857 Rudolf Clausius, considered one of the central founders of the science of thermodynamics, put forward a detailed kinetic theory of gases, which implied velocities for gas molecules of several hundred metres per second.  However the Dutch meteorologist Christoph Buys-Ballot pointed out it takes over a minute for a release of foul-smelling gas to be noticed at the other end of a room, whereas at the speeds suggested by Clausius the molecules should have traversed the space several times in one second!  So, was Rudolf C. a red-faced reindeer?  Not at all! He modified his theory to allow molecules to have a significant finite, rather than infinitesimal size.  So they would collide frequently, and the molecular jostling would put a real damper on the speed of diffusion.  And so it is.  Things dry out much more quickly under vacuum where the water molecules whiz away unimpeded.

So, here we have two gadflies who prompted a genius to come up with a deeper theory that encompasses a greater amount of phenomena in its scope.  Alas, although Daniel Bernoulli had earlier come up with a truly quantitative kinetic theory of gases, it was too far removed from the general conceptions of the time.  Had there been a gadfly to take him on and inspire him to great effort, maybe the theory might have taken the common ground earlier.

But to me the most amusing case is that of Boyle and Linus.  Robert Boyle was a strong advocate of the idea that it was simply air pressure that held up the mercury in a barometer, as put forward by Torricelli.   But he was opposed by Francis Line, aka Linus, who pointed to the suction felt at the top of a barometer tube (or these days, a vacuum cleaner hose) if it was closed by a finger.  Linus suggested that Nature, abhorring a vacuum, caused the tube or finger to give off an invisible entity which he called funiculus, being Latin for ‘little rope’, which closed up the space and prevented a vacuum.  Boyle did not ignore Linus, but went on to more experiments and reasoning through which he derived the now-famous Boyle’s Law, which he might not have done but for the prompting.
 
And what was it again, the Latin for a “little rope?”  Something to do with cable railways? Funiculi Funicula [2]  …… Warning!  I am about to SING!

[1] Synthese  Volume: 119    Issue: 1-2    Pages: 11-43    Published: 1999  

[2] Neopolitan Lyrics with English Translation