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"Physical
laws should have mathematical beauty"
-Dirac
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For
hundreds of years, scientists have used and abused the language of
mathematics in an effort to describe the behaviour of the physical world.
Yet as they succeed in describing one set of facts, they fail to
describe another. It is as
though the scientists are trying to fit a carpet that is too big for the
room: they push down in one corner, only to have the opposite corner pop
up. The greatest
breakthroughs in physical science have come from those with the insight to
strip away the layers of complexity; to cut the carpet.
But will the carpet ever be cut small enough?
Can the natural world ever be fully explained with mathematics?
It is staggering that any relationships can be established between
the two. Mathematics is so
abstract, built on concepts with no physical meaning, like number and
proof. Yet this intangible
systems seems to hold reign over the natural world.
Insights in one branch yield insights in the other; a bridge has
been built between the unbridgeable.
In Tom Stoppard’s Arcadia Thomasina Coverly
embodies a fundamental human drive – the desire for knowledge. A scientist is born and not bred; she is the child who always
asks “why”. Thomasina
demonstrates this instinctive curiosity early in the play, asking about
Fermat’s Last Theorem. Born
in 1601 to a leather merchant, Pierre de Fermat became a legal clerk by
trade. (It is his lack of formal training that earned Fermat the
nickname “Prince of Amateurs” among mathematicians.) Fermat read widely, and was fond of annotating texts.
In 1637 he left a marginal note in Diophantus’ masterwork, Arithmetica
that has intrigued and puzzled mathematicians for more than 350 years.
He stated that “it is impossible to separate… any power above
the second into two powers of the same degree”.
In more modern notation, we say that the equation xn
+ yn = zn has no solution in whole numbers if n
is greater than two. (Any
GCSE mathematics student will recognise the case when n equals two
as Pythagoras’ Theorem.) This
problem owes its fame in no small part to the fact that Fermat claimed he
has a “truly marvellous” proof of the theorem, but gave no details.
This was the famous “note in the margin”, which Thomasina
claims was simply “a joke to make you all mad.”
Did Fermat really have a proof?
Unlikely. British
mathematician Andrew Wiles finally published a correct proof in 1994, but
this could not have been the proof Fermat may have had.
Wiles’ proof took the simple problem of Fermat’s Last Theorem,
and solved it using complicated twentieth century techniques.
Fermat’s problem was so simple, so smooth, that to get a grip on
it it was necessary to add many layers of complexity.
Wiles had to work, in Thomasina’s words, “outward from the
middle of the maze.”
Thomasina’s
interest in mathematics flourishes later in the play as she turns her
attention to geometry. In
trying to describe the mathematical equation of a leaf she talks of the
creation of a “new geometry of irregular forms”. The geometry to which Thomasina refers is fractal geometry.
In this, a set of instructions, called an algorithm, is applied to
a number or a shape. These
instructions might be “square the number and add one”, or “copy the
shape, rotating the copy through 45 degrees”. The same set of instructions are then re-applied to the
resulting number or shape, producing a new one.
The repetition of this process is called iteration, and
fractal geometry deals with the behaviour of shapes and numbers under
iterated algorithms. Thomasina
carries out a few iterations in her notebook.
But as Valentine demonstrates, modern computers can take the
process to new levels, iterating an algorithm thousands, or even millions
of times. It is the self
similarity in this process that allows it to model nature so accurately
– each branch of a fern leaf is like a miniature copy of the whole leaf.
Thomasina questions Septimus before making her discovery, asking if
“nature is written in numbers”. All
we can be sure of is that mathematical patterns crop up again and again in
the natural world. Numbers
are certainly written in nature.
The idealism of the young Thomasina becomes apparent
when she claims that “if you could stop every atom in its position and
direction… then if you were really really good at algebra you could
write a formula for all the future.”
This concept – the deterministic universe – was
destroyed earlier this century with the birth of Heisenburg’s
Uncertainty Principal. Werner
Heisenburg showed that the greater the certainty with which you know where
an atom is, the lesser the certainty with which you know how it is moving.
In order for Thomasina’s “formula for all the future” to be
calculated you would need to know exactly where every atom was, exactly
which way it was moving, and exactly how quickly.
Impossible, said Heisenburg. Simply
by observing an atom you are bouncing light off it, altering its velocity.
This fundamental principle has led to the study of quantum
mechanics – describing the behaviour of atoms in terms of
probability rather than certainty.
Thomasina’s formula would also rely on Newton’s
equations being the fundamental rules determining how all objects behave.
Thomasina challenges herself here, asking “is God a Newtonian?”
In 19th century England, when copies of Newton’s Principia
adorned every coffee table in the country, this might have been considered
sacrilege. But Newton’s
laws are simply a theorem; a scientific model that Newton formulated to
best model the facts he had. In
the last century, Newton’s laws have been superceded by another model:
Einstein’s relativity. Is this scientific theory the magna carta for the
behaviour of the universe? No.
Will another, more accurate model replace it?
Almost certainly. And
with each cut of the carpet, we find ourselves closer to a solution.
However, it is my beliefs that as close as we may get to that
solution, we will never attain it. The
laws that govern our universe are simply too wonderful to be laid down in
the language of mathematics, and too abstract to be understood by any
human being.
As
Arcadia draws to a close, and disorder takes hold of Sidley Park,
Thomasina makes her most startling observation, the second law of
thermodynamics. As
immortalised in the Flanders and Swann lyric “heat won't pass from the
cooler to the hotter/ you can try it if you likes but you'd far better
notter,” the second law states that heat must flow from hot to cold, and
that whenever work is done energy is irrecoverably turned into heat.
In reality discovered jointly by Clausius in 1850 and Kelvin in
1851, it is the second law of thermodynamics that means we need energy to
power our fridges as well as our cookers.
The directional nature of the law means that it acts as a one-way
sign for the universe. If
time were to be reversed all physical laws would still hold, with the
exception of the second law of thermodynamics – heat would be seen to
flow from cold to hot. The
second part of the law is the most alarming.
If all energy must be irrecoverably be turned to heat, the universe
is destined to become a featureless desert, a fraction of a degree warmer
than absolute zero. “The
improved Newtonian universe must cease and grow cold.”
Thomasina first notices this consequence when stirring her rice
pudding. The jam must become irrecoverably mixed in – “disorder
out of disorder until pink is complete.”
All of Thomasina’s ideas concern simplicity and
complexity in the physical world and the way it is described. Newton’s laws, fractal geometry, the second law of
thermodynamics, even Fermat’s problem, all attempt to tell us something
about the way the world works. By
increasing the complexity of the problems – by adding more structure –
we attempt to get closer to the truth.
Sadly, but inevitably, we fall so far short.
Do the answers lie in simple equations like that of Fermat’s Last
Theorem, or in vast, complex formulae like Thomasina’s “equation of
the future”? Perhaps time
will tell. But through this
uncertainty one thing becomes clear: Mathematics and Science are in their
infancy, whereas Nature is fully matured.
Perhaps it is time we learnt to walk before we can run.
HARRY SMITH
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