Nanoparticle trapped with laser light temporarily violates the second law of thermodynamics

Mar 31, 2014 by Mag. Veronika Schallhart
Artistic impressions of the nanoparticle in a laser trap. Credit: Iñaki Gonzalez and Jan Gieseler

Objects with sizes in the nanometer range, such as the molecular building blocks of living cells or nanotechnological devices, are continuously exposed to random collisions with surrounding molecules. In such fluctuating environments the fundamental laws of thermodynamics that govern our macroscopic world need to be rewritten. An international team of researchers from Barcelona, Zurich and Vienna found that a nanoparticle trapped with laser light temporarily violates the famous second law of thermodynamics, something that is impossible on human time and length scale.

They report about their results in the latest issue of the prestigious scientific journal Nature Nanotechnology.

Surprises at the nanoscale

Watching a movie played in reverse often makes us laugh because unexpected and mysterious things seem to happen: glass shards lying on the floor slowly start to move towards each other, magically assemble and suddenly an intact glass jumps on the table where it gently gets to a halt. Or snow starts to from a water puddle in the sun, steadily growing until an entire snowman appears as if molded by an invisible hand. When we see such scenes, we immediately realize that according to our everyday experience something is out of the ordinary. Indeed, there are many processes in nature that can never be reversed. The physical that captures this behavior is the celebrated , which posits that the entropy of a system – a measure for the disorder of a system – never decreases spontaneously, thus favoring disorder (high entropy) over order (low entropy).

However, when we zoom into the microscopic world of atoms and molecules, this law softens up and looses its absolute strictness. Indeed, at the nanoscale the second law can be fleetingly violated. On rare occasions, one may observe events that never happen on the macroscopic scale such as, for example heat transfer from cold to hot which is unheard of in our daily lives. Although on average the second law of thermodynamics remains valid even in , scientists are intrigued by these rare events and are investigating the meaning of irreversibility at the nanoscale.

Artistic impressions of the nanoparticle in a laser trap. Credit: Iñaki Gonzalez and Jan Gieseler

Nanoparticles in laser traps

Recently, a team of physicists of the University of Vienna, the Institute of Photonic Sciences in Barcelona and the Swiss Federal Institute of Technology in Zürich succeeded in accurately predicting the likelihood of events transiently violating the second law of thermodynamics. They immediately put the mathematical fluctuation theorem they derived to the test using a tiny glass sphere with a diameter of less than 100 nm levitated in a trap of . Their experimental set-up allowed the research team to capture the nano-sphere and hold it in place, and, furthermore, to measure its position in all three spatial directions with exquisite precision. In the trap, the nano-sphere rattles around due to collisions with surrounding gas molecules. By a clever manipulation of the laser trap the scientists cooled the nano-sphere below the temperature of the surrounding gas and, thereby, put it into a non-equilibrium state. They then turned off the cooling and watched the particle relaxing to the higher temperature through energy transfer from the gas molecules. The researchers observed that the tiny glass sphere sometimes, although rarely, does not behave as one would expect according to the second law: the nano-sphere effectively releases heat to the hotter surroundings rather than absorbing the heat. The theory derived by the researchers to analyze the experiment confirms the emerging picture on the limitations of the second law on the nanoscale.

Nanomachines out of equilibrium

The experimental and theoretical framework presented by the international research team in the renowned scientific journal Nature Nanotechnology has a wide range of applications. Objects with sizes in the , such as the molecular of or nanotechnological devices, are continuously exposed to a random buffeting due to the thermal motion of the molecules around them. As miniaturization proceeds to smaller and smaller scales nanomachines will experience increasingly random conditions. Further studies will be carried out to illuminate the fundamental physics of nanoscale systems out of equilibrium. The planned research will be fundamental to help us understand how nanomachines perform under these fluctuating conditions.

Explore further: First thin films of spin ice reveal cold secrets

More information: "Dynamic Relaxation of a Levitated Nanoparticle from a Non-Equilibrium Steady State." Jan Gieseler, Romain Quidant, Christoph Dellago, and Lukas Novotny. Nature Nanotechnology AOP, February 28, 2014. DOI: 10.1038/NNANO.2014.40

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antialias_physorg
not rated yet Mar 31, 2014
On a completely unrelated note: Can you make a living as an artist doing these "Artists impression of scientific phenomenon X"? The further science delves into exotic regions (microscopic as well as cosmological) the more often these seem to be encountered.
Horus
not rated yet Mar 31, 2014
On a completely unrelated note: Can you make a living as an artist doing these "Artists impression of scientific phenomenon X"? The further science delves into exotic regions (microscopic as well as cosmological) the more often these seem to be encountered.


Probably, until they have an interface for an Electron Microscope that produces RAW images capable of being later described with 16 bit per channel RGBA.
TransmissionDump
5 / 5 (2) Mar 31, 2014
Artistic impressionism might sell for millions one day.
Shabs42
not rated yet Mar 31, 2014
My favorite are the impressions of planets. I do always wonder how they get them so quickly, and how closely they work with the researchers to make them as accurate as possible.
HealingMindN
not rated yet Mar 31, 2014
It's a far cry from the Millikan Oil Drop Experiment. My college probably had all the equipment to do it back in the 80's too.
richardwenzel987
4.5 / 5 (2) Apr 01, 2014
In regard to the backward movie thing, I don't think that really illustrates what entropy would look like in reverse. Consider the puddle of water. If it did result from a melting snowman, consider all the possible configurations that could converge on a particular puddle of water of a certain volume. In reality, isn't it the case that randomization of movement in the high entropy state makes it impossible to recover a specific prior lower entropy state? The backward movie is actually another process entirely, and does not really illustrate an entropy reversal or reversed arrow of time. If you had a puddle of water that resulted from a melting snowman, and you reversed time's arrow, you would still have a puddle of water.
dedereu
not rated yet Apr 02, 2014
temporarily, it fluctuates, but the second law remains valid, with theses fluctuations around the equilibrium, increasing when the size decreases, like Brownian motion !!
Nothing fundamentally new .
Zwentoo
Apr 02, 2014
This comment has been removed by a moderator.
Zwentoo
Apr 02, 2014
This comment has been removed by a moderator.
russell_russell
not rated yet Apr 03, 2014
Any state will have information that is irretrievable from a flow of time. Note: the information is irretrievable and lost (lost, as in you don't where the previous information is now) not destroyed.
A puddle of water is maxed out entropy as far as information and the snowman are concerned.
The information for the original snowman is irretrievable, not destroyed. No amount of time of any direction can retrieve the information. Puddles are here to stay.

Any recorded event (film) has less information than the event itself.
richardwenzel987
not rated yet Apr 06, 2014
I wonder whether some prior low entropy system or state that played a pivotal role in determining the current make-up of the universe might have subsequently evolved into the equivalent of a "puddle", with information now non-recoverable. That would leave us forever without data needed to have a complete cosmology or complete theory.
russell_russell
not rated yet Apr 06, 2014
The cells you were born with are all long gone. That leaves you forever without data needed to complete you.

No two cells of any life form you know are indistinguishably identical.
All electrons are indistinguishably identical.

If you pick a point on a number line, then there is no present day method to FIND the point you picked from any method known presently.

If we can agree to an assumption that (if) a number line is complete (continuous), then the point you picked on the line exists. All the information, all the points, all the data on a number line exist.

From both our perspectives all the data ever needed exists to form a complete theory.
(That's hidden cheer-leading for and from principles of conservation.)

The SEARCH METHOD to find all the data ever needed to form a complete theory is incomplete, insufficient and necessary. There is no shortage or lack of data. Ever.

Beyond principles of conservation are principles of emergence.
The shipbuilders of Theseus.
Returners
not rated yet May 20, 2014
[quote]The researchers observed that the tiny glass sphere sometimes, although rarely, does not behave as one would expect according to the second law: the nano-sphere effectively releases heat to the hotter surroundings rather than absorbing the heat. The theory derived by the researchers to analyze the experiment confirms the emerging picture on the limitations of the second law on the nanoscale.[/quote]

This implies a mathematical formulation needs to be derived for the second law to explain/quantify/relate this phenomena to it's environment in order to represent these "apparent exceptions" to the rule. If there are exceptions to the rule, or apparent exceptions, then the exceptions are themselves rules, presumably, and we should be able to find and describe them all, at least approximately.
Returners
not rated yet May 20, 2014
richardwenzel987:

Very good argument about the snowman and the puddle of water. I have made similar arguments in the past.

There was this scientist on Through the Wormhole who claimed that running a video in reverse was a valid physical process, and I pointed out that no, it certainly wasn't, and no such process would occur in nature.

In Sci-Fi when people see "time reversal" they typically think of running a video in reverse, but that is not valid in physics.

If you reversed time, photons would not fly back into the sun and re-merge with helium atoms and "un-fuse" them back into Hydrogen, as you might expect from a time-reversed video tape.

If we take the acceleration formula, or the position formula, which contains a term equal to the acceleration formula, and we insert "negative time" you end up with something quite different from a time-reversed video.

P1 = P0 + v0t + (1/2)a(t^2)

If t is negative, then initial velocity is negative, but acceleration is still positive...