From the archive, originally posted by: [ spectre ]



February 2, 2007


LONDON, England (Reuters) — Nearly 150 years ago it was no more than
a concept by a visionary scientist, but researchers have now created a
minuscule motor that could lead to the creation of microscopic

Scottish physicist James Clerk Maxwell first imagined an atom-size
device dubbed Maxwell’s Demon in 1867. Scientists at the University of
Edinburgh have made it a reality.

“We have a new motor mechanism for a nanomachine,” said David Leigh, a
professor of chemistry at the University.

A nanomachine is an incredibly tiny device whose parts consist of
single molecules. Nature uses nanomachines for everything from
photosynthesis to moving muscles in the body and transferring
information through cells.

Scientists are trying to unravel the secrets of nanomachines and
nanotechnology, which works on a tiny scale. One nanometer is a
billionth of a meter, or about 80,000 times smaller than the thickness
of a human hair.

“Molecular machines allow life itself to occur at a molecular level.
Our new motor mechanism is a small step towards doing that sort of
thing with artificial molecular machines,” Leigh told Reuters.

His mechanism traps molecular-sized particles as they move. As Maxwell
had predicted long ago, it does not need energy because it is powered
by light.

“While light has previously been used to energize tiny particles
directly, this is the first time that a system has been devised to
trap molecules as they move in a certain direction under their natural
motion,” said Leigh who reported the findings in the journal Nature.

“Once the molecules are trapped, they cannot escape.”

Leigh credits Maxwell for establishing the fundamentals for
understanding how light, heat and molecules behave.

In an earlier study, he and his team showed that a nanomachine could
move a drop of water uphill by using molecular force. Although the
movement was small, it was a big step in learning to make machines
with artificial molecules.

The new motor mechanism will enable scientists to do things that are
much closer to what biological machines do.

Nanotechnology is already being used in cosmetics, computer chips,
sunscreens, self-cleaning windows and stain-resistant clothing.

Leigh believes nanoscale science and engineering could have a huge
impact on society — comparable to the impact of electricity, the
steam engine and the Internet.

But quite how, is difficult to predict.

“It a bit like when stone-age man made his wheel asking him to predict
the motorway,” he said.

“It is a machine mechanism that is going to take molecular machines a
step forward to the realization of the future world of nanotechnology.
Things that seem like a Harry Potter film now are going to be a
Professor David A. Leigh

David [dot] Leigh [at] ed [dot] ac [dot] uk’s_demon

James Clerk Maxwell (13 June 1831 – 5 November 1879) was a Scottish
mathematician and theoretical physicist. His most significant
achievement was formulating a set of equations – eponymically named
Maxwell’s equations – that for the first time expressed the basic laws
of electricity and magnetism in a unified fashion. He also developed
the Maxwell distribution, a statistical means to describe aspects of
the kinetic theory of gases. These two discoveries helped usher in the
era of modern physics, laying the foundation for future work in such
fields as special relativity and quantum mechanics. He is also known
for creating the first true colour photograph in 1861.

” (The work of Maxwell) … the most profound and the most fruitful
that physics has experienced since the time of Newton.” -Albert
Einstein, The Sunday Post[1]

The majority of Maxwell’s illustrious career took place at the
University of Cambridge, where his investigations often made use of
his mathematical aptitude, drawing on elements of geometry and
algebra. With these skills, Maxwell was able to demonstrate that
electric and magnetic fields travel through space, in the form of
waves, and at the constant speed of light. Finally, in 1861 Maxwell
wrote a four-part publication in the Philosophical Magazine called On
Physical Lines of Force where he first proposed that light was in fact
undulations in the same medium that is the cause of electric and
magnetic phenomena.

Maxwell is considered by many, especially those within the field of
physics, to be the scientist of the nineteenth century most
influential on twentieth century physics. His contributions to physics
are considered by many to be of the same magnitude as those of Isaac
Newton and Albert Einstein. In 1931, on the centennial anniversary of
Maxwell’s birthday, Einstein described Maxwell’s work as the “most
profound and the most fruitful that physics has experienced since the
time of Newton.”

James Clerk Maxwell was born on June 13, 1831. in Edinburgh, Scotland
(his birthplace, at 15 India Street, is now the location of the
International Centre for Mathematical Sciences), to John Clerk and
Frances (née Cay) Maxwell. It was at this time that physicist Michael
Faraday was in the process of completing his work on magnetic
induction, a concept upon which Maxwell would later build.

Maxwell grew up on his father’s estate in the Scottish countryside. He
was encouraged by his father to pursue his scientific and mathematical
interests, Maxwell entered college at the age of 16 and eventually
graduated with high honors in mathematics.

All indications suggest that Maxwell had maintained an unquenchable
curiosity from an early age. Everything that moved, shone, or made a
noise sparked an interest in the young boy.[2] In a letter to her
sister Jane Cay in 1834, his mother describes this innate sense of

He is a very happy man, and has improved much since the weather
got moderate; he has great work with doors, locks, keys, etc., and
‘show me how it doos’ is never out of his mouth. He also investigates
the hidden course of streams and bell-wires, the way the water gets
from the pond through the wall…[3]

Recognizing the potential of young Maxwell, his mother Frances took
responsibility for his early education, which in Victorian times was
largely the job of the women of the house. She became ill – probably
with cancer – and died in 1839. His father, John Clerk Maxwell,
undertook the education of his son, with the aid of his sister-in-law
Jane Cay, both of whom played pivotal roles in the life of James. His
formal education began, unsuccessfully, under the guidance of a hired
tutor. Not much is known about the man James’s father hired to
instruct his son, except that he treated the younger Maxwell harshly.
His educational philosophy was founded upon coercion, often physical.
James never responded well to the tutor’s instruction; he chided his
student for being slow and wayward. After considerable searching, John
Maxwell sent James to the Edinburgh Academy. His school nickname was
“Daftie”, earned when he arrived for his first day of school wearing
home-made shoes.

Maxwell was captivated by geometry at an early age, rediscovering the
regular polyhedra before any formal instruction. Much of his talent
went unnoticed however, and his academic work remained unremarkable
until, in 1845 at the age of 13, he won the school’s mathematical
medal, and first prizes for English and for English verse. For his
first piece of original work, at the age of 14, Maxwell wrote a paper
describing mechanical means of drawing mathematical curves with a
piece of twine and properties of ellipses and curves with more than
two foci. This work, Oval Curves, was published in an issue of the
Royal Society of Edinburgh, and although it shows the curiosity of
Maxwell at a young age, it is important to note that the work itself
was not mathematically profound. Unlike other great minds, such as
Gauss, Pascal or Mozart, Maxwell was not a child prodigy. Rather, his
genius would slowly mature.

Maxwell left the Academy and began attending class at the University
of Edinburgh. Having the opportunity to attend Cambridge after his
first term, Maxwell decided instead to complete the full three terms
of his undergraduate studies at Edinburgh. The main reason for this
was that Cambridge was too far from home, and he would only have the
opportunity to see his father twice a year. Another reason was
Maxwell’s concern for his future. He wanted to become a scientist, but
jobs in science were rare at this time, and it would have been
difficult to obtain a lecturing post at a university. Accordingly,
Maxwell completed his studies at Edinburgh in natural philosophy,
moral philosophy, and mental philosophy under Sir William Hamilton,
9th Baronet. In his eighteenth year he contributed two papers for the
Transactions of the Royal Society of Edinburgh – one of which, On the
Equilibrium of Elastic Solids, laid the foundation for an important
discovery of his later life: the temporary double refraction produced
in viscous liquids by shear stress.

In 1850, Maxwell left for Cambridge University and initially attended
Peterhouse, but eventually left for Trinity College where he believed
it was easier to obtain a fellowship. At Trinity, he was elected to
the secret society known as the Cambridge Apostles. In November 1851,
Maxwell studied under the tutor William Hopkins (nicknamed the
“wrangler maker”). A considerable part of the translation of his
electromagnetism equations was accomplished during Maxwell’s career as
an undergraduate in Trinity.

In 1854, Maxwell graduated with a degree as second wrangler in
mathematics from Trinity (i.e. scoring second-highest in the final
mathematics examination) and was declared equal with the senior
wrangler of his year in the more exacting ordeal of the Smith’s prize
examination. For more than half of his relatively short life, he held
a prominent position in the foremost rank of scientists, usually as a
college professor. Immediately after taking his degree, he read to the
Cambridge Philosophical Society a novel memoir, On the Transformation
of Surfaces by Bending. This is one of the few purely mathematical
papers he published, and it exhibited at once to experts the full
genius of its author. About the same time, his elaborate memoir, On
Faraday’s Lines of Force appeared, in which he gave the first
indication of some of the electrical investigations which culminated
in the greatest work of his life.

From 1855 to 1872, he published at intervals a series of valuable
investigations connected with the Perception of Colour and Colour-
Blindness, for the earlier of which he received the Rumford medal from
the Royal Society in 1860. The instruments which he devised for these
investigations were simple and convenient in use. For example,
Maxwell’s discs, seen in the photograph above, were used to compare a
variable mixture of three primary colours with a sample colour by
observing the spinning “colour top.” In 1856, Maxwell was appointed to
the chair of Natural Philosophy in Marischal College, Aberdeen, which
he held until the fusion of Aberdeen’s two colleges in 1860.

In 1859, he won the Adams prize in Cambridge for an original essay, On
the Stability of Saturn’s Rings, in which he concluded the rings could
not be completely solid or fluid. Maxwell demonstrated stability could
ensue only if the rings consisted of numerous small solid particles,
which he called “brickbats”. He also mathematically disproved the
nebular hypothesis (which stated that the solar system formed through
the progressive condensation of a purely gaseous nebula), forcing the
theory to account for additional portions of small solid particles.

In 1860, he was a professor at King’s College London. In 1861, Maxwell
was elected to the Royal Society. He researched elastic solids and
pure geometry during this time.

One of Maxwell’s greatest investigations was on the kinetic theory of
gases. Originating with Daniel Bernoulli, this theory was advanced by
the successive labours of John Herapath, John James Waterston, James
Joule, and particularly Rudolf Clausius, to such an extent as to put
its general accuracy beyond a doubt; but it received enormous
development from Maxwell, who in this field appeared as an
experimenter (on the laws of gaseous friction) as well as a

In 1865, Maxwell moved to the estate he inherited from his father in
Glenlair, Kirkcudbrightshire, Scotland. In 1868, he resigned his Chair
of Physics and Astronomy at King’s College, London.

In 1866, he statistically formulated, independently of Ludwig
Boltzmann, the Maxwell-Boltzmann kinetic theory of gases. His formula,
called the Maxwell distribution, gives the fraction of gas molecules
moving at a specified velocity at any given temperature. In the
kinetic theory, temperatures and heat involve only molecular movement.
This approach generalized the previously established laws of
thermodynamics and explained existing observations and experiments in
a better way than had been achieved previously. Maxwell’s work on
thermodynamics led him to devise the thought experiment that came to
be known as Maxwell’s demon.

The greatest work of Maxwell’s life was devoted to electricity.
Maxwell’s most important contribution was the extension and
mathematical formulation of earlier work on electricity and magnetism
by Michael Faraday, André-Marie Ampère, and others into a linked set
of differential equations (originally, 20 equations in 20 variables,
later re-expressed in quaternion and vector-based notations). These
equations, which are now collectively known as Maxwell’s equations (or
occasionally, “Maxwell’s Wonderful Equations”), were first presented
to the Royal Society in 1864, and together describe the behaviour of
both the electric and magnetic fields, as well as their interactions
with matter.

Maxwell showed that the equations predict the existence of waves of
oscillating electric and magnetic fields that travel through empty
space at a speed that could be predicted from simple electrical
experiments; using the data available at the time, Maxwell obtained a
velocity of 310,740,000 m/s. In his 1864 paper A Dynamical Theory of
the Electromagnetic Field, Maxwell wrote,

The agreement of the results seems to show that light and
magnetism are affections of the same substance, and that light is an
electromagnetic disturbance propagated through the field according to
electromagnetic laws.

Maxwell was proved correct, and his quantitative connection between
light and electromagnetism is considered one of the great triumphs of
19th century physics.

At that time, Maxwell believed that the propagation of light required
a medium for the waves, dubbed the luminiferous aether. Over time, the
existence of such a medium, permeating all space and yet apparently
undetectable by mechanical means, proved more and more difficult to
reconcile with experiments such as the Michelson-Morley experiment.
Moreover, it seemed to require an absolute frame of reference in which
the equations were valid, with the distasteful result that the
equations changed form for a moving observer. These difficulties
inspired Einstein to formulate the theory of special relativity, and
in the process Einstein dispensed with the requirement of a
luminiferous aether.

Maxwell also made contributions to the area of optics and colour
vision, being credited with the discovery that colour photographs
could be formed using red, green, and blue filters. He had the
photographer Thomas Sutton photograph a tartan ribbon three times,
each time with a different colour filter over the lens. The three
images were developed and then projected onto a screen with three
different projectors, each equipped with the same colour filter used
to take its image. When brought into focus, the three images formed a
full colour image. The three photographic plates now reside in a small
museum at 14 India Street, Edinburgh, the house where Maxwell was

Maxwell’s work on colour blindness won him the Rumford Medal by the
Royal Society of London. He wrote an admirable textbook of the Theory
of Heat (1871), and an excellent elementary treatise on Matter and
Motion (1876). Maxwell was also the first to make explicit use of
dimensional analysis, also in 1871.

In 1871, he was the first Cavendish Professor of Physics at Cambridge.
Maxwell was put in charge of the development of the Cavendish
Laboratory. He supervised every step of the progress of the building
and of the purchase of the very valuable collection of apparatus paid
for by its generous founder, the 7th Duke of Devonshire (chancellor of
the university, and one of its most distinguished alumni). One of
Maxwell’s last great contributions to science was the editing (with
copious original notes) of the electrical researches of Henry
Cavendish, from which it appeared that Cavendish researched such
questions as the mean density of the earth and the composition of
water, among other things.

Maxwell married Katherine Mary Dewar when he was 27 years of age, but
they had no children. He died in Cambridge of abdominal cancer at the
age of 48. He had been a devout Christian his entire life. Maxwell is
buried at Parton Kirk, near Castle Douglas in Galloway, Scotland.