快猫短视频

IT鈥橲 EARLY August and a small group of men and women from many countries
gather in a classroom, tucked away in a quiet courtyard at Cambridge University.
With the students on holiday, conferences like this are an everyday event at the
university. But as the day progresses, things begin to look distinctly odd.

Most of the speakers are chemists, and while they are all talking science,
they present no data. Instead of complex equations, their talks are dotted with
terms like 鈥渇uzzy reasoning鈥�, 鈥渙ntology鈥�, and 鈥減ostmodernism鈥�. At one point,
delegates even discuss the importance of tissues for wiping runny noses.

But this small gathering鈥攖he second meeting of the International
Society for the Philosophy of Chemistry鈥攔epresents the tentative
beginnings of a new field. The 15 chemists and philosophers present are looking
hard at the much-neglected philosophical underbelly of chemistry for anything
from grand theories of matter to useful metaphors derived from the everyday work
of chemists toiling in the lab over complex instruments and reactions. And so
far, it鈥檚 all looking very interesting.

The subject certainly offers uncharted waters to philosophers. While quantum
mechanics and natural selection have given philosophers of physics and biology
much food for thought, few philosophers have explored what chemistry has to
offer. 鈥淚t鈥檚 interesting and puzzling why we have a philosophy of physics and a
philosophy of biology but there鈥檚 no philosophy of chemistry,鈥� says Davis Baird,
a philosopher at the University of South Carolina in Columbia.

So does chemistry have any similarly grand theories on which to build a
philosophy of chemistry? Until recently, many philosophers have simply
overlooked the field, maybe by accepting the well-worn view that chemistry is
nothing more than applied physics. This 鈥減hysics imperialism鈥� claims that
anything鈥攁 chemical reaction, an orchid, an erupting volcano, a telephone
conversation鈥攃an be completely explained by the fundamental laws of
physics. But this reductionist approach is not always successful, says Eric
Scerri, a chemist at Purdue University in West Lafayette, Indiana, and a strong
campaigner for the philosophy of chemistry. In particular, he argues, important
facets of chemistry have not been explained by quantum mechanics鈥攁 fact
that many philosophers overlook (see 鈥淲rong filling鈥�).

Scerri has published numerous papers on the problems of reduction in both
chemical and philosophical journals and is the editor of a new journal called
Foundations of Chemistry due to be launched early next year. And his
campaign to put the philosophy of chemistry firmly on the map is gaining
momentum.

A growing number of people have begun to consider chemistry from a
philosophical viewpoint. More than 250 people have now joined an Internet
mailing list dedicated to discussions on the philosophy of chemistry. And Baird
suspects the group of dedicated researchers鈥攁s well as the mailing
list鈥攚ill grow. 鈥淭here鈥檚 a whole pile of interesting science and history
of science that has been unexplored from the philosophical point of view,鈥� he
says.

Like Scerri, Baird draws philosophical inspiration from chemistry. Baird is
studying what chemistry can reveal about our understanding of the nature of
matter by looking at how chemists build and use scientific instruments like
lasers, detectors and spectrometers.

Philosophers are interested in the nature and status of the human belief
systems and truth claims that are put forward to describe the material world.
Some philosophers regard the world as being governed by laws: everything in the
world, be it a tennis match, an autumn leaf or this magazine, is simply an
expression of laws. For them a scientific instrument is nothing more than a
magnifying glass which helps researchers to read the 鈥渓aw book鈥� and weigh those
laws against each other.

While Baird respects this view of reality, he thinks this way of working is
an oversimplification. Viewing instruments as nothing more than information
producers ignores the material nature of the world: he believes that theories
and information are no substitute for real objects鈥攖hings that have size,
mass and shape. Ignore these, and you miss the wider picture鈥攚hat Baird
describes as 鈥渢he thinginess of things鈥�.

As an example, during his talk at the Cambridge meeting he displays an image
of a tissue and raises the problem of a runny nose. 鈥淲hen you need a Kleenex,
information about it simply won鈥檛 do,鈥� says Baird. Having a thorough
understanding of the tissue鈥檚 shape, structure and size won鈥檛 solve the problem
in hand. 鈥淵ou need a physical thing,鈥� he says.

And instruments themselves express our knowledge of the way the world works
in a way that no single theory ever could. Before a chemist can use a scientific
instrument, someone must design and build it using their knowledge of the
Universe and its laws of physics, chemistry, optics and electronics. So
scientists express their knowledge of the world in a variety of different ways:
not just through theories such as quantum mechanics, but also through objects
such as scientific instruments.

Baird believes chemists understand their instruments intuitively and don鈥檛
use them merely as 鈥渃onduits鈥� for information. Unlike theoretical physicists,
they work in the 鈥渞eal 鈥� world, which is made up of messy bunches of buzzing
molecules in different states鈥攈ot and cold, big and small, solid and
liquid. Chemists must coax their results from within this white noise of
statistical errors. The very nature of the material world is built into their
instruments. Philosophers of science who consider only the laws of physics to be
worth studying could learn a good lesson from them, he says.

But how can one define, or even describe, what constitutes a material thing?
Where is the boundary between a Kleenex and a theory? And even though the
Kleenex is made of fibres, which themselves have internal structure, we consider
it a single thing. Why?

Here again it should be possible to draw new philosophical ideas from
chemistry. Joe Earley certainly thinks so. He is a chemist from Georgetown
University in Washington DC, whom Scerri introduces to the conference as 鈥渢he
very embodiment of a philosopher of chemistry鈥�. Earley, who has been thinking
philosophically about chemistry for more than twenty years, tells the meeting
that by looking at chemical reactions, philosophers can devise a new definition
of what constitutes a 鈥渢hingy thing鈥�.

Earley claims philosophers have been too content with a narrow view of what
counts as a 鈥渢hing鈥�. To most philosophers, a material object must be something
like a rock鈥攕omething held together by forces, producing a tangible object
that functions as one unit and resists change. But there are many dynamic
objects, Earley says, that philosophers have difficulty describing. Take a storm
cloud. 鈥淚t鈥檚 a swarm of rapidly moving air molecules, but it鈥檚 also a unit,鈥�
Earley says. In such systems, simple components or processes can work together
to generate a more complex whole.

Chemists鈥� expertise lies in dealing with parts that combine into larger
wholes, says Earley鈥攁toms combining into molecules, for example. And he
has found an example from chemistry that can help to define for philosophers how
the components of dynamic objects must balance to produce a unified
whole鈥攐scillating chemical reactions.

These are reactions that cycle through distinct states only to come back to
the starting point and begin all over again. A well-known example is the
Belousov-Zhabotinsky reaction, in which concentrations of ions oscillate
regularly (see 鈥淟et T equal tiger鈥�, 快猫短视频, 6 November 1993, p
40). 鈥淵ou have something that is an autocatalytic process, where one makes two,
makes four, makes eight鈥攕omething exploding. Then there鈥檚 some control
mechanism that shuts that down and starts you again. Explode, shut off, explode,
shut off,鈥� says Earley.

To him, balancing these processes so that the cycle repeats indefinitely
produces a whole that is more than the sum of its parts. The components
constitute one 鈥渢hing鈥� because they work together and the chemical reactions
influence each other to achieve a balance. 鈥淭hat鈥檚 the thinginess of that
thing,鈥� he says.

Earley suggests that all oscillating reactions have four characteristics (see
鈥淩ound in circles鈥�). When all four are present, the components of the
reaction interact to produce a larger structure that functions as a single unit.
This unit can even act in coordination with other units to produce yet larger
composite wholes, Earley believes.

Earley thinks this model of a 鈥渃omposite whole鈥� works from the micro to the
macro scale. Just as an oscillating chemical reaction is a composite whole, so
are a kitten, the Sun and a storm cloud. So, too, is a community of people and
their environment, interacting through a multitude of cyclic processes. 鈥淭hey
must be considered together鈥攁s one,鈥� says Earley.

鈥淚鈥檓 not saying this isn鈥檛 a strange way of looking at things,鈥� Earley
admits. But it is a powerful tool: 鈥淥nce you start looking at things this way,
then you can see its influence all over the place.鈥�

Earley, like Scerri and Baird, has begun to produce a distinctly chemical
answer to a philosophical question, and many more questions remain. Chemistry
may not yet offer the world a single theory that raises the challenging
questions posed by, say, quantum mechanics. But it鈥檚 certainly giving
philosophers a new angle on familiar questions. And Earley, Scerri and Baird
hope others will join their pursuit of knowledge through analysing
chemistry.

Perhaps Earley鈥檚 concept of autocatalysis will even apply to the
International Society for the Philosophy of Chemistry. The enthusiasm of the few
in the field now may bring in more enthusiasts. If this group establishes a
cycle with new members joining as others leave, they just might create a unit
that persists indefinitely. Then perhaps the philosophy of chemistry will have
become larger than the sum of its parts鈥攁nd a true thing.

鈥淭HE reduction of chemistry to physics is supposed to happen automatically,
and people seldom question it,鈥� Eric Scerri notes. So how is it, he asks, that
the heart of modern chemistry鈥攖he periodic table鈥攈as never been
explained successfully by the laws of physics.

Mendelyev designed his table on the basis of experiment: arranging the
elements roughly by weight and lining up elements with similar properties into
columns. When quantum mechanics arrived, its laws gave chemists a way to
describe the motion of electrons around the nuclei of atoms. But despite its
achievements, quantum mechanics failed to justify the ordering of the elements
in the table.

Electrons are thought to orbit atomic nuclei in a series of 鈥渃oncentric鈥�
shells. According to quantum mechanics, these shells should fill sequentially as
you move from one element to the next along a row. And this does occur, but only
as far as potassium. 鈥淭hat鈥檚 where the trouble starts,鈥� Scerri says.

Potassium鈥檚 outer-most electron sits in the fourth shell, even though 10 of
the 18 spaces in the third shell remain empty. Its neighbour, calcium, behaves
the same way. But then the next element, scandium, 鈥渞emembers鈥� that the third
shell is not yet full and puts its extra electrons into it. 鈥淚f the shells were
to fill in a sequential order, we would have a perfect quantum mechanical
explanation of the periodic table,鈥� says Scerri. But they don鈥檛.

Although the periodic table may one day be reduced successfully to physics,
Scerri doesn鈥檛 believe chemistry as a whole ever will be. 鈥淵ou will never reduce
all of chemistry,鈥� he says. And without this, the philosophy of chemistry can
never be reduced to the philosophy of physics.

Even chemists have overlooked this failure of reduction, Scerri says. Many
chemistry teachers explain the periodic table backwards, Scerri
thinks鈥攖hey begin with shell filling and end up with the elements arranged
in the table. Some textbooks even state that quantum theory predicts the
structure of the periodic table.

THERE are four requirements for a chemical system to oscillate indefinitely,
says Joe Earley, a chemist from Georgetown University in Washington DC.

* The system must be far from equilibrium. Most chemical reactions move
smoothly towards an equilibrium state, going from reactants to products. But
these systems are not 鈥渨holes鈥濃�攖hey contain products with little or no
influence over one another.

* There must be autocatalysis, or positive feedback. Once started, the
reaction must feed on itself and speed up. The product of the reaction causes
yet more product to form. Without some check, this reaction would simply
accelerate out of control, so the oscillating system must have an 鈥渆xit鈥�
reaction. As the product builds up, it is simultaneously removed by another
chemical reaction running in parallel.

* The components above must work together to create a cycle. When the amount
of the product is low, autocatalysis speeds up the primary reaction so it is
faster than the exit reaction. This forms more of the product. As the product
builds up, the exit reaction starts to occur faster than the autocatalytic
reaction, reducing the amount of product. And the cycle continues.