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06/27/2000
Applause, Applause
Last week, I noted that I am among the rhythmically challenged
and in a theater or concert hall experience great difficulty trying
to clap in unison with the rest of the audience. I wasn''t planning
to pursue this deficiency any further but, when flipping through
the July issue of Discover magazine, I had to reconsider. There
was an article entitled "Joining Hands", about the mathematics of
applause. Actually, there wasn''t a single equation in the article,
which deals primarily with the work of Steven Strogatz, associate
professor of theoretical and applied mechanics at Cornell
University. Strogatz is among the many workers these days who
are involved in the study of chaos, appropriately, a very popular
subject in our chaotic world. One dictionary definition of chaos is
"an extreme disorder or confusion" but in today''s scientific arena
chaos is better defined as "the seemingly random behavior of
systems that are otherwise governed by precise mathematical
laws" (taken from the Cornell Web site).
I''m trying to remember when it was that I first encountered
synchronous applause. I certainly had not heard it here in the
U.S.A. at any concert or play until perhaps 20 years ago. As best
I can remember, my first encounter with CIU (clapping in unison)
was during a visit to the Soviet Union in 1973. I believe it
followed a magnificent performance of the opera "Faust"
performed in the Kremlin. I might have thought at that time that
this CIU was just a Communist-inspired approach to conformity
in every aspect of life. This was during the time of Leonid
Brezhnev and the iron curtain was still down. Ironically, in
Hungary CIU is called ''iron'' applause, a term that arose from the
fact that an iron curtain would descend between the audience and
the stage after a performance. The audience would then engage
in CIU to call back the artists, who would appear through a door
in the iron curtain. However, as in Russia, the iron curtain is
gone.
Back to Strogatz and chaos, which seems just the opposite of
CIU. Ordinary applause, however, consists of people clapping in
an unstructured fashion, at different rates and intensities and thus
qualifies as being at least mildly chaotic. One of the goals of
those studying chaos is to develop methods of predicting the
future behavior of chaotic systems, weather and the stock market
being two very practical examples. Another approach is to use
chaos to achieve a particular goal, for example, to ensure the
privacy of communications. In an earlier column we discussed
methods of encrypting data to protect the privacy of transactions
on the Internet.
Strogatz and his colleagues reportedly are the first to demonstrate
that "synchronized chaos" could be used to send and receive a
message that would be unintelligible to the casual eavesdropper.
In the old days, spies would stand by a noisy waterfall or fountain
to mask their conversations. Strogatz and company used
electronic circuits to take a message and mask it with much
louder chaotic ''noise'' to make it sound like static. The trick is
that the receiver of the message has to have the ability to
synchronize perfectly with the chaos part and subtract it out. This
leaves the message itself, coming through loud and clear. Don''t
ask me how they did it. I have no idea.
Much like Bob, our professor of linguistics in last week''s column,
Strogatz is interested in synchronization in nature. Phenomena
such as the synchronous chirping of crickets, emergence of 17-
year cicadas together (yuck, I''ve had experience with them!) and
synchronization of menstrual cycles of women living together in
dorms, etc. (I''ve had no experience with the latter!) And it all
seems to have begun with Christiaan Huygens in 1665 when he
found that two clocks hanging side by side would end up with
their pendulums (pendula) swinging in rhythm with each other,
"self-entrainment", as we discussed last week. The clocks
influenced each other through the vibrations transmitted through
the walls that they were touching.
So, how does CIU come about in an audience that is clapping in a
more or less chaotic manner? Here, the crickets provide a clue
Strogatz did experiments where he kept crickets in soundproof
chambers and would then pipe in the sounds of other crickets at
increasing volumes. When the volume got loud enough, the
cricket in the chamber would join in synchronous chirping. The
key seems to be the critical volume and not just a gradual flow
toward synchronization. A similar effect occurs in CIU but, first,
the audience has to want to clap in unison. When the applause
begins, everybody is clapping at a different rate and there are no
beats to be heard. Now, if a few individuals happen to hit a beat
just by accident, that beat will stand out in the general chaos of
the applause and those who were looking for a beat will join in
and suddenly the whole audience is engaged in CIU. All but me,
of course!
Applause is more complicated than I thought. The Discover
article also mentions the work of Tamas Viscek and Albert-
Laszlo Barabasi of Notre Dame University and Zoltan Neda of
Babes-Bolyai University in Romania. These collaborators are
really serious investigators of clapping, hanging microphones
from the ceilings of concert halls in Romania and recording the
applause. Analyses of the recordings showed a consistent pattern
of applause, with several periods of CIU separated by periods of
what they describe as "incoherent cacophony". They also found
that clapping was about half as fast in CIU compared to the rate
of clapping in the chaotic, cacophonic state. Why the periods of
chaotic clapping alternating with CIU? Here, the feeling is that
it''s due to crowd psychology. Barabasi and Viscek think that
CIU induces a "cozy feeling of togetherness", while the chaotic
clapping, which is faster and generally at a higher noise level,
indicates more enthusiasm. So the audience tends to alternate
between these two.
My opening comment about CIU (written before I had finished
the Discover article) possibly being related to conformity may be
more accurate than I suspected. Barabasi was a child in
communist Romania under the rule of Nicolae Ceausescu. When
that tyrannical dictator would give a speech, the audience
responded by clapping in unison continuously, with no breaks into
chaotic clapping. In 1989, a few days before Christmas, he
organized a rally of some 250,000 people to show support for
him. The crowd began to clap synchronously but suddenly the
clapping stopped, shooting started and the revolution had begun.
On Christmas day Ceausescu and his wife were shot dead!
Who knows? Perhaps, if Ceausescu had noticed the absence of
chaotic clapping after his speeches, he might have realized the
lack of enthusiasm for his regime and modified his rule to a kinder
and gentler one. If so, he might still be alive today.
Allen F. Bortrum
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