[wordup] Administrivia and the Second law of thermodynamics disproven

[Adam Shand]

Hey all.

Back from a long holiday exploring the South Island with Teresa.  I'm 
in the process of catching up with email so you can expect postings to 
resume in the near future.

Also due to the fact that the spammers are now trolling the list 
archives I'm stopping attaching the contributors email.  If you have 
any better suggestions (or simply don't care and wish that I'd just 
ignore the spammers all together) please let me know.

Adam.

Via: Mike Messick
From: http://news.bbc.co.uk/1/hi/sci/tech/2135779.stm

Thursday, 18 July, 2002, 11:09 GMT 12:09 UK
Beads of doubt
By Dr David Whitehouse
BBC News Online science editor

One of the most important principles of physics, that disorder, or 
entropy, always increases, has been shown to be untrue.

Scientists at the Australian National University (ANU) have carried out 
an experiment involving lasers and microscopic beads that disobeys the 
so-called Second Law of Thermodynamics, something many scientists had 
considered impossible.

The finding has implications for nanotechnology - the design and 
construction of molecular machines. They may not work as expected.

It may also help scientists better understand DNA and proteins, 
molecules that form the basis of life and whose behaviour in some 
circumstances is not fully explained.

No discussion

Flanders and Swann wrote a famous song entitled The First And Second 
Law about what entropy meant and its implications for the physical 
world. It has become a mantra for generations of scientists.

The law of entropy, or the Second Law of Thermodynamics, is one of the 
bedrocks on which modern theoretical physics is based. It is one of a 
handful of laws about which physicists feel most certain.

So much so that there is a common adage that if anyone has a theory 
that violates the Second Law then, without any discussion, that theory 
must certainly be wrong.

The Second Law states that the entropy - or disorder - of a closed 
system always increases. Put simply, it says that things fall apart, 
disorder overcomes everything - eventually. But when this principle is 
applied to small systems such as collections of molecules there is a 
paradox.

Human scales

This Second Law of Thermodynamics says that the disorder of the 
Universe can only increase in time, but the equations of classical and 
quantum mechanics, the laws that govern the behaviour of the very 
small, are time reversible.

A few years ago, a tentative theoretical solution to this paradox was 
proposed - the so-called Fluctuation Theorem - stating that the chances 
of the Second Law being violated increases as the system in question 
gets smaller.

This means that at human scales, the Second Law dominates and machines 
only ever run in one direction. However, when working at molecular 
scales and over extremely short periods of time, things can take place 
in either direction.

Now, scientists have demonstrated that principle experimentally.

Fraction of a second

Professor Denis Evans and colleagues at the Research School of 
Chemistry at the Australian National University put 100 tiny beads into 
a water-filled container. They fired a laser beam at one of the beads, 
electrically charging the tiny particle and trapping it.

The container holding the beads was then moved from side to side a 
thousand times a second so that the trapped bead would be dragged first 
one way and then the other.

The researchers discovered that in such a tiny system, entropy can 
sometimes decrease rather than increase.

This effect was seen when the researchers looked at the bead's 
behaviour for a tenth of a second. Any longer and the effect was lost.

Emerging science

The scientists say their finding could be important for the emerging 
science of nanotechnology. Researchers envisage a time when tiny 
machines no more than a few billionths of a metre across surge though 
our bodies to deliver drugs and destroy disease-causing pathogens.

This research means that on the very small scales of space and time 
such machines may not work the way we expect them to.

Essentially, the smaller a machine is, the greater the chance that it 
will run backwards. It could be extremely difficult to control.

The researchers said: "This result has profound consequences for any 
chemical or physical process that occurs over short times and in small 
regions."

The ANU work is published in Physical Review Letters.