Crowd Physics

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During my early years of teaching First Years at IIT KGP half a century back, I had to take a couple of lectures on Architectural Acoustics; remember that there was a full-fledged naughty Department of Architecture.

Apart from reverberation time and stuff, there was this topic of absorption of sound in an auditorium. It was never easy to manufacture a perfect 100% absorber of sound. So, they found that an open window of a square meter size in a big hall acts as a substitute; sound just disappears from the hall with hardly any reflection.

So it was chosen as a standard Unit of acoustic absorption and was called OWU (Open Window Unit). Subsequently it was renamed as a Sabin after W C Sabine.

Interestingly, the absorption of a standard well-built male seated in the auditorium was calculated as so many OWUs...maybe the number is different for ladies...size per size, ladies have lot more fat and skin-glow.

So, as everyone who performed in a Music Hall knows, an empty hall is a veritable hell to perform in because there will be too much reverberation (echo). A good-sized audience is a must.

Well, I never 'performed' music (chin or otherwise), but for my livelihood I had to perform Physics in a variety of Lecture Halls at KGP, from Raman, Bhatnagar to the sundry Shilas.

Personally, I found teaching Quantum Physics to a Second Year B Tech Class of Chemical Engineers in F - 127 most challenging and satisfying (around 1990 - 93). The crowd was about 60 no-nonsense students.

Well, no student of IIT KGP has ever been naive. They were all connoisseurs...if you talk sense, they are willing to listen whatever the topic. And it is impossible to bluff them, although it is easy to inveigle them by telling relevant stories.

Anyway during those days, the attendance was more or less full and the number of 60 OWUs was just right for Quantum Music. I made many 'friends' during those three years and they should be as happy with me in hindsight as I am with them.

Teaching Physics students of less than 20 in Phy Dept Class Rooms was different...it didn't call for dramatics or 'selling' QM...they mostly needed cereal not fish. And I can't call them 'friends'...they were more like 'soul mates'...we floated or sank together.

Handling the first Lecture Class of 60 Second Year Chemical Engineering students was always a thing that activated fluttering butterflies in the abdomen. The feeling is incomparably subtle.

That is about absorption of sound.

A crowd also 'emits' heat. I don't know if there is any standard unit of heat emission for a well-built male...females I think are fairer and so not nearly good enough blackbodies.

This stream of thought came up because today I read a piquant news item in DC.

Apparently the Shiv Ling of Ice in the Amarnath Cave is melting fast this year. Earlier on, any anomaly like this tended to be attributed to that whipping boy called Global Warming.

But not this year. It was pretty cool. And a decent enough column of ice did form.

But apparently the crowds this time are unmanageably large. Maybe because many were held up many days due to avalanches or snow-storms or such road blocks.

So the tiny 'temple' housing the formation was overcrowded for too many hours and the body heat emitted by them started to melt the ice away. And the Grand Finale on Shravan Poornima (Rakhee) is a month away and there are fears that it would be a flop show.

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Talking of Lecture Halls, here is our Autocrat on the 'sameness' of the average crowd in a Lecture Hall:

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Two lyceum assemblies, of five hundred each,
are so nearly alike, that they are absolutely undistinguishable in
many cases by any definite mark, and there is nothing but the place
and time by which one can tell the "remarkably intelligent
audience" of a town in New York or Ohio from one in any New England
town of similar size.  Of course, if any principle of selection has
come in, as in those special associations of young men which are
common in cities, it deranges the uniformity of the assemblage.
But let there be no such interfering circumstances, and one knows
pretty well even the look the audience will have, before he goes
in.  Front seats:  a few old folk,--shiny-headed,--slant up best
ear towards the speaker,--drop off asleep after a while, when the
air begins to get a little narcotic with carbonic acid.  Bright
women's faces, young and middle-aged, a little behind these, but
toward the front--(pick out the best, and lecture mainly to that.)
Here and there a countenance, sharp and scholarlike, and a dozen
pretty female ones sprinkled about.  An indefinite number of pairs
of young people,--happy, but not always very attentive.  Boys, in
the background, more or less quiet.  Dull faces here, there,--in
how many places!  I don't say dull PEOPLE, but faces without a ray
of sympathy or a movement of expression.  They are what kill the
lecturer.  These negative faces with their vacuous eyes and stony
lineaments pump and suck the warm soul out of him;--that is the
chief reason why lecturers grow so pale before the season is over.
They render LATENT any amount of vital caloric; they act on our
minds as those cold-blooded creatures I was talking about act on
our hearts.

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