杏吧原创

LIKE any great work of art, Marty Quinn鈥檚 Climate Symphony was
inspired. Not by love, anguish or drugs, however. Quinn鈥檚 muse was a cylinder of
ice.

This inspirational ice core was drilled from a glacier in Greenland. The snow
that built the glacier contained carbon dioxide, methane and other gases, along
with bits of sulphate, potassium and dust. As you go deeper into the ice, the
different chemistry corresponds to the atmospheric conditions at the time the
snow fell. That way, scientists can see what was happening to the climate up to
110,000 years ago.

But why turn it into a symphony? 鈥淚鈥檓 really into experiencing data in new
ways through music, to enhance perception of information,鈥� says Quinn, a
musician and artist in New Hampshire. Apparently, he鈥檚 not alone. Nowadays, data
from protein structure, earthquakes, brain waves and lightning on Jupiter are
being used to generate music. Some people believe this union of music and
science is overdue, and that it may allow scientists to hear patterns in their
work that they would otherwise miss. On the other hand, it could just be an
artistic gimmick.

It all started with sounds rather than real music. For decades, results been
turned into sound as a way to help researchers who are visually impaired, says
Larry Scadden, director of science education for students with disabilities at
the National Science Foundation in Arlington, Virginia. Making sounds out of
information traditionally expressed by visual tools like graphs or tables became
known as sonification. More people than ever are now doing it, as they realise
the advantages of hearing over vision. Whereas our eyes sometimes slide over
mistakes like a repeated word or minor omissions, our ears are better at
perceiving subtle changes in volume, pitch and rhythm.

It was perhaps inevitable that scientists should begin to search for beauty
in these sounds. After all, they often expound on the elegance of their
experiments or equations. Why shouldn鈥檛 science sound good too? Sonification was
about to become songification.

Donald Gurnett, a physicist at the University of Iowa, has seen it happen.
Gurnett studies radio waves emitted by the gases of interplanetary space. He
takes records of those waves and slows them down so that their frequencies are
in a range audible to the human ear. That lets him listen for the characteristic
sounds of phenomena such as lightning on Jupiter, Earth鈥檚 aurora and cosmic
radiation belts. He鈥檚 even heard radio waves in the furthest reaches of the
solar wind, sampled by the Voyager I spacecraft.

To Gurnett, the sounds are interesting, even pleasant; but he wouldn鈥檛 call
them music. He plays me a tape of the aurora, putting the receiver of his phone
next to a cassette recorder. At first, there is nothing, then a sound like a
single, slightly muffled laser gun from Star Wars. Then another, then
three more. Soon, it鈥檚 a full-on intergalactic battle.

High-energy electrons streaming into the Earth鈥檚 atmosphere cause the aurora.
鈥淭he electrons aren鈥檛 coming down like steady rain, they are coming down in
organised packets.鈥� That mysterious clumping is what makes the staccato burst of
sound.

Gurnett has been listening to space sounds for almost 40 years, but it was
only last year that NASA came to him with the idea of making music. The agency鈥檚
art programme, based in Washington DC, commissioned composer Terry Riley to turn
Gurnett鈥檚 collection of sounds into a score. It will be performed in 2002 by the
San Francisco-based Kronos Quartet. It鈥檚 a nice bit of public relations from
NASA, a highly image-conscious organisation. But in a way it is
cheating鈥攖he music will only be inspired by scientific data, not actually
generated directly from it.

Physicist Michael Berry at the University of Bristol takes a much more direct
mathematical approach. He has tried to hear patterns in the prime numbers using
a sequence of numbers called the Riemann zeroes鈥攚hich are of profound
mathematical interest. Among other things, the zeroes are related to the prime
numbers in a seemingly arcane way. But Berry says they have a more accessible
property. They are notes in the harmony of the primes, reflecting the frequency
with which prime numbers crop up. In theory, you can hear these notes.

To test the idea, Berry programmed the first thousand or so prime numbers
into his PC. The output is a simple click for each prime, timed according to the
size of the number. The many clicks should merge into a set of notes, a mystic
chord that encapsulates the essence of number theory.

Unfortunately, this first attempt produced nothing more than a hectic
machine-gun noise, says Berry. He鈥檇 like another go at it someday, with more
computing power to include more primes. But even the unpleasant-sounding mess
was informative, he claims. 鈥淚t鈥檚 like hearing chaos in the primes.鈥�

Most songifiers manipulate their data more heavily, giving the science a
music lesson before letting it play. At the University of Exeter, Helen Long
generates music based on protein structures (New 杏吧原创,10 February,
p 21). Long uses three-dimensional maps of proteins gleaned from X-ray
crystallography. She then assigns sounds of different pitch and duration to
various atom types. This turns visual features of the protein into coherent
musical structures. For example, the spring-like shape of a helix becomes an
arpeggio, and polypeptide chains are represented by a succession of identical or
neighbouring notes. Later this year, her work will be featured as an interactive
exhibit at the Explore-at-Bristol science centre. Through a touch screen, users
will pick different proteins found in the body, and then hear them translated
into music. Long hopes to find out if these molecular melodies have any
therapeutic properties. There is no clinical evidence supporting the notion, but
many people have said the music is soothing and uplifting, she says.

Perhaps the most prolific songifier is Marty Quinn. He has made music from
DNA sequences, the flux of energetic particles from the Sun, the variations in
El Ni帽o and, most recently, earthquakes.

Seismologists gather records of ground shaking to find out where an
earthquake was, what type of fracture caused it and how much energy was
released. They also want to know if seismic waves will be strengthened or
weakened as they travel through the rock. If the waves travel over long
distances, they can reveal details of the Earth鈥檚 internal structure.

But most people think of seismology as simply an up-and-down wiggle on a
paper trace, says Christel Hennet of the Incorporated Research Institutions for
Seismology in Washington DC. So Hennet teamed up with Quinn to create the
Seismic Sonata, to give people a better feeling for the nature of seismic
data.

The sonata was based on ground motions recorded after the 1994 Northridge
Earthquake near Los Angeles, California. Quinn simply matched up a set of 45
different notes to the violence, or amplitude of the shaking at each moment. An
oboe plays the corresponding notes over the entire 15-minute selection.

Because most of the notes correspond to moderate or violent shaking, the
beginning was a little flat. For a while before the main quake strikes, the oboe
plays a single note, as if the Earth were absolutely still. But closer
inspection of the data reveals background noise, whether from distant
earthquakes or nearby vibrations, which seismologists pay attention to and which
Quinn wanted to incorporate in the music.

To convey this deeper complexity, Quinn used what he calls an 鈥渁udio-zoom鈥�.
Scaling the data to represent more detailed, 3-second intervals, he assigned a
piano to play this more fine-grained portion. He then overlaid the piano with
the oboe in the final version, 鈥渁s if you were looking at a diamond with your
naked eye and a jeweller鈥檚 lens at the same time鈥�. This way, the listener
experiences the general trend of the wave motion over time, while also hearing
the complexity and commotion of Earth鈥檚 tiniest movements.

At first, Quinn tried to bounce back and forth between records from three
separate monitoring stations throughout the sonata, but the result was too
disjointed, he says鈥攖he listener would not have been able to grasp any
sense of the waves travelling through time and space. 鈥淵ou have to ask: what
aspects of the information do you want to leave in, and what is most important,鈥�
says Quinn. To preserve the continuity of the wave sounds, he decided to use a
single monitoring station in Albuquerque, New Mexico, so the listener could
clearly hear each of the different waves hit over time.

The result impressed Hennet. 鈥淲ith 20 data points coming in every second,
when you listen to the rapid up and downs, the complexity of the information
jumps out at you. You really get a sense of the motions. It ends up being this
fascinating, cascading sound.鈥� Could a person ever play it? 鈥淚t鈥檚 just about at
virtuoso level,鈥� says Quinn. 鈥淢aybe Yo-Yo Ma.鈥�

Quinn鈥檚 greatest success so far is his Climate Symphony. This was
composed using data supplied by Paul Mayewski, a climatologist then at the
University of New Hampshire. Mayewski helped to extract patterns in the Earth鈥檚
past climate from the traces of gases such as carbon dioxide and potassium in
the ice. Changes in the Earth鈥檚 orbit and variations in the brightness of the
Sun will cause fluctuations in temperature over different timescales. Other
climate factors are recorded directly in the ice鈥攄ust from volcanic
eruptions and ammonium from burning forests.

Quinn鈥檚 aim was to make the symphony portray all these natural patterns over
the past 110,000 years. Arpeggios of three notes represent the tilt in the
Earth鈥檚 axis. High notes for greater tilt, lower for less. The instrument that
plays any particular set of arpeggios represents the vigour of the ocean
circulation during a particular period. Tom-toms play in the background when the
world is warm, bells ring when it is cooler, and other climate factors have
their own signatures, or modify each other鈥檚 sounds. Throughout the piece, the
string section plays a rising scale, over five octaves, to represent the passing
of time.

Instead of just looking at 鈥渟quiggly lines on a page鈥�, says Quinn, people can
experience the changes in climate as they listen to his symphony. Maybe so, but
all the massaging and crunching of numbers for the sake of easy listening leaves
me wondering whether the point of the exercise is lost in the process. To my
ears, untrained in music or atmospheric chemistry, the symphony sounds like a
storm of mostly aimless notes. It is possible to notice short sequences of notes
scaling up or down, especially one booming portion鈥攙aguely reminiscent of
Tchaikovsky鈥檚 1812 overture鈥攃orresponding to a period of
particularly violent volcanic eruptions. But without the guidance of Quinn or
another expert, making connections between changes in the music and changes in
climate history is nearly impossible. Quinn says that鈥檚 not his goal. 鈥淥f course
listeners are not going to hear all of the data, but they鈥檒l get something out
of it, and they鈥檙e going to feel the changes in the Earth on a gut
濒别惫别濒.鈥�

Purely as music, how does it rate? Well, knowing the derivation of the notes
makes it kind of cool, but I鈥檓 not rushing out to buy the CD. For a museum
exhibit or alternative teaching tool, songified tunes are great. At a
candlelight dinner for two, however, I鈥檇 stick with music inspired by something
other than science.