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2nd Law of Thermodynamics.... ....

is WRONG??!!!!
ok... doesn't hold true in all cases..

so much for immutable laws..... as the article states, its one of the laws that no one questions.... and its wrong....

thats what i love about science.. that there's no dogma. nothing is taken as "word"...

http://news.bbc.co.uk/1/hi/sci/tech/2135779.stm

Quote:

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.

ANU team
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

ok... minus all the hype. so it seems that it might be violated in some instances.. but statistically, the law still holds true.. and the law holds for large systems..

so no perpetual motion machines for now...
http://www.aip.org/enews/physnews/2002/598.html

Quote:

Pushing the Second Law to the Limit

Australian researchers have experimentally shown that microscopic systems (a nano-machine) may spontaneously become more orderly for short periods of time--a development that would be tantamount to violating the second law of thermodynamics, if it happened in a larger system. Don't worry, nature still rigorously enforces the venerable second law in macroscopic systems, but engineers will want to keep limits to the second law in mind when designing nanoscale machines. The new experiment also potentially has important ramifications for an understanding of the mechanics of life on the scale of microbes and cells.

There are numerous ways to summarize the second law of thermodynamics. One of the simplest is to note that it's impossible simply to extract the heat energy from some reservoir and use it to do work. Otherwise, machines could run on the energy in a glass of water, for example, by extracting heat and leaving behind a lump of ice. If this were possible, refrigerators and freezers could create electrical power rather that consuming it. The second law typically concerns collections of many trillions of particles--such as the molecules in an iron rod, or a cup of tea, or a helium balloon--and it works well because it is essentially a statistical statement about the collective behavior of countless particles we could never hope to track individually. In systems of only a few particles, the statistics are grainier, and circumstances may arise that would be highly improbable in large systems. Therefore, the second law of thermodynamics is not generally applied to small collections of particles.

The experiment at the Australian National University in Canberra and Griffith University in Brisbane (Edith Sevick, sevick@rsc.anu.edu.au, 011+61-2-6125-0508) looks at aspects of thermodynamics in the hazy middle ground between very small and very large systems. The researchers used optical tweezers to grab hold of a micron-sized bead and drag it through water. By measuring the motion of the bead and calculating the minuscule forces on it, the researchers were able to show that the bead was sometimes kicked by the water molecules in such a way that energy was transferred from the water to the bead. In effect, heat energy was extracted from the reservoir and used to do work (helping to move the bead) in apparent violation of the second law.

As it turns out, when the bead was briefly moved over short distances, it was almost as likely to extract energy from the water as it was to add energy to the water. But when the bead was moved for more than about 2 seconds at a time, the second law took over again and no useful energy could be extracted from the motion of the water molecules, eliminating the possibility of micron-sized perpetual motion machines that run for more than a few seconds. Nevertheless, many physicists will be surprised to learn that the second law is not entirely valid for systems as large as the bead-and-water experiment, and for periods on the order of seconds. After all, even a cubic micron of water contains about thirty billion molecules. While it's still not possible to do useful work by turning water into ice, the experiment suggests that nanoscale machines may have to deal with phenomena that are more bizarre than most engineers realize. Such tiny devices may even end up running backwards for brief periods due to the counterintuitive energy flow. The research may also be important to biologists because many of the cells and microbes they study comprise systems comparable in size to the bead-and-water experiment. (G.M. Wang et al., Physical Review Letters, 29 July 2002.)

I don't think this comes as a surprise.

Consider four molecules in a box. The second law would suggest that they should never be on the same side of the box. But statistically, it happens sometimes.

What about four million molecules? Again, despite the law, it is statistically possible. Just very unlikely.

The Second Law, ultimately, is not a true "Law" but a description of what is statistically most likely. In most cases, it is not only most likely, but overwhelmingly most likely. But on the small-scale, exceptions to the "Law" become more likely than on the large-scale. There is no magical force that makes the Second Law work -- it is merely an overall consequence of statistical mechanics, just as Newtonian mechanics seems to work on the large-scale but is really just an overall consequence of more sophisticated physics.

"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."

Yup..

-SF

this is significant? I'm surprised that anyone was claiming that thermodynamics should work at the atomic level--statistical mechanics depends on the existence of a large ensemble in a newtonian world...

LOL!

So they only consider their system for 1/10 of a second. This hardly proves that entropy was decreasing!

I suppose these fools are the same ones who believe in the "synchronous theory" (ie. the opposite to the chaos theory) whereby all things attempt to find a syncronous harmony.

These people seriously need to take a few stats courses.

Going back to the decreasing entropy issue ... a system that appears to (and this is key) _spontaneously_ decrease in entropy has always been a possibility .. the important consideration is that with time, the system will achieve a higher entropy.

Let's consider another problem - how are they defining entropy? Let's first consider that these twits are conducting the experiment in water (think hydrogen bonds, Brownian motion, heat in the system) If decreasing entropy (increasing in order) ocurrs .. perhaps van der Waal might have something to say about forces of attraction. Let's ignore the fact that as a laser passes through water, it will impart energy into the system, changing the experiment entirely (think kinetics, think charged bodies attracting non-charged).

This whole experiment is retarded. The experimenters should go back to testing whether hot water freezes faster than cold.

don't some people argue that the 2nd law is somehow proof of gods existance?

I did a similar experiment that proved the same thing as these guys did, only on a Newtonian scale. The other day, I spontaneously picked up a bunch of old magazines in my room and put them in a pile. On a timescale of anything up to ten minutes, the entropy of the pile of magazines was seen to decrease. Anything longer than a couple of days and they get scattered around again. Can I have my PhD now, please?

Honestly, what a bunch of assfucks.

Quote:

Originally posted by f00sion
don't some people argue that the 2nd law is somehow proof of gods existance?

Actually I thought it was the 1st law that somehow disproved God's existence (the old 'what created God' theme) or proved it, depending on your view point.

I can't, at least right now, see how the second law would be proof of God's existence...

In other news, you still cant push a rope.

Small scale, short term? Sure, why not. That really might be handy for nanotech. Nothing to write home about yet, and we're still a ways from the Diamond Age.

what about human beings... we are a very complex organism that is highly orderd system breaking the 2nd law...

now we could get into some philosophical discussion in here about how through natural processes such a highly ordered system could not exist in a universe of disorder and that a higher being must of created the ordered system

or the way i see it is that we are just a more efficient disorder creating system...

if any of that made sense

Quote:

Originally posted by vegeta0283
what about human beings... we are a very complex organism that is highly orderd system breaking the 2nd law...

now we could get into some philosophical discussion in here about how through natural processes such a highly ordered system could not exist in a universe of disorder and that a higher being must of created the ordered system

or the way i see it is that we are just a more efficient disorder creating system...

if any of that made sense

Human beings don't break the 2nd Law because neither people nor the earth are a closed system. We take in energy by eating -- energy that originates from the sun.

The disorder created by the sun's nuclear fusion is greater than the order of life on Earth.

Quote:

Originally posted by lordjeebus
The disorder created by the sun's nuclear fusion is greater than the order of life on Earth.

I second that argument--the theologician who came up with the "human beings break the 2nd law" argument absolutely without a doubt did not have a science degree. anyone who has taken college physics should be able to see through it. name one scientific article in favor of the human being exception argument...i would love to read it...

Here is a better counter-argument:

Sure, in the short term .. humans can be considered to be more highly ordered .. however, what happens when you die?

A glass mug is highly ordered, but when it is dropped .. what happens?

S = k ln W

:D

there is no law, only working theory.
and quantum physics will throw a wrench in most of what we "know" anyway.

Lordjeebus, rsl1 Its nice to see I'm not the only one to have survived physics.

Quote:

Originally posted by tecoyah
there is no law, only working theory.
and quantum physics will throw a wrench in most of what we "know" anyway.

:thumbsup:

What we have termed scientific "law" is constantly being challenged. New information can't be forced to comply with what we have supposed to be universal rules. The "law" of gravity has little or no application on the quantum level. If the 2nd Law of Thermodynamics loses meaning on a sub-atomic scale, what of it? We can only make deductions based on observable phenomena, and make assumptions on how they apply to the unobservable. If those assumptions are wrong, get over it!

So easy for someone to simply come along and tell us what we already know: laws are only an explanation of what we understand within the context of our knowledge

Try actually adding to the debate :rolleyes: