Tuesday, March 11, 2008

Bourbon Street Physicists

Hi there, physics lovers! Physics Buzz has temporarily headed south... to gorgeous New Orleans for the APS annual March Meeting! Just a little too late for Mardi Gras, we’re being kept very busy with over 7,000 talks in 5 days, plus press conferences and workshops. We'll be posting about the interesting talks we see and all the additional excitement. I’ve already seen talks on the physics of motorcycles, new theories about the interior structure of Jupiter, the physics of snake movement (which included a video of snakes in jackets!), and many others. Keep posted for more news.

The March Meeting is primarily an opportunity for physicists to share their research with other physicists in their field. Every once in a while, it’s also a chance to reveal a major discovery that affects more fields of physics or even the world at large. One press conference focused on some of these major breakthroughs and included a talk on the creation of gold, lead and tin fullerenes. Physics Buzz recently had an article about the first team to image carbon fullerenes, better known as buckyballs, or tiny soccer-ball-like cages made of carbon atoms.

These cages don’t exist in nature, and are made up of only 60 carbon atoms each. Sculpture on that scale is very difficult; we’re talking about specifically manipulating the structure of just a few dozen atoms! Lai-Sheng Wang presented his group’s creation of cages made of lead, gold, and tin. These metals all have very different properties from carbon, and will offer new applications as the science develops. Almost before researchers found they could successfully create these cages, they were working on how to put things inside them (which the team successfully did). Putting an atom inside a cage that is made up of another type of atom can alter the cage material’s chemical properties. It also offers the possibility of using the fullerenes as atomic transports.

Some people are focused on other things when they come to the March Meeting. Here is the Editor in Chief of Physical Review, Gene Sprouse, showing off mad skills (just kidding of course. Although Gene is a very talented yo-yoer, he spends most of his time keeping the journals running strong).

Another breakthrough was the development of 3D optical lattices consisting of individual atoms, in which the atoms are far enough apart that they can be individually manipulated without disturbing their neighbors. David Weiss presented the data from Penn State. Imagine making small cubes out of toothpicks, held together at the joins by balls of clay. You could put a group of these together to then make a larger cube looking somewhat like a square jungle-gym. This is essentially a lattice, and scientists have found ways to put a single atom at each joint (where the balls of clay are). The atoms are then equally spaced apart, and take up a 3D space. Now that you’ve got those atoms where you want them, the objective is then to manipulate them. But the challenge thus far has been manipulating single atoms without disturbing their neighbors, which had to be very close by. The scientists were able to separate the atoms by 5 microns.

An additional press conference focused on the physics of climate change. There were no ground breaking discoveries to be reported in this field, but rather an underlying message from the six speakers: physicists must develop more qualitative and robust ideas about climate models if they can hope to make predictions about future climate trends. While scientists are, unquestionably, able to observe climate changes, they cannot yet create a system model that will determine why these changes occur, or give any indication of future trends. Quantitative methods are all but impossible to obtain because of the scale they need to be on (the entire frickin Earth!). Speakers noted that there are few, if any, sessions at physics meetings being focused primarily on climate change. There is only one session focused solely on climate change at the March Meeting, and they hope that number will increase at future meetings.

Shortly after the meeting, I’ll be posting an interview I did with Daniel Goldman about his research on animals that move on granular surfaces like sand and mud. He and his team built the sandbot to mimic this motion. The group thinks they’ve found some fundamental similarities between the way very different animals move on these surfaces (some of them moving at over 2 meters per second!!). It’s a wonderful example of how physics may answer some age-old questions posed by biologists, but also how physicists can learn fro nature’s living models. And of course, it raises new questions for both fields.

Stay tuned physicsbuzzers!! More to come!

1 comment:

  1. Entropy. / My opinion /.
    Henry Poincare named the conception of "entropy "
    as a " surprising abstract ".
    L. Landau (Dau) wrote:
    " A question about the physical basis of the
    entropy monotonous increasing law remains open ".
    The famous mathematician John von Neumann said to
    "the father of information theory" Claude Shannon:
    " Name it "entropy" then in discussions
    you will receive solid advantage, because
    nobody knows, what "entropy" basically is ".
    Between 1850 - 1865 Rudolf Clausius published a paper
    in which he called " The energy conservation law" as
    " The first law of thermodynamics". But in our nature the
    heat always flows from the higher temperature to the
    lower one and never back. In our everyday life we don't see
    the heat itself rises from cold to hot. So, it seemed that
    in thermodynamics " The energy conservation law"
    wasn’t kept, this law was broken. But Clausius had another
    opinion. He thought: I know people believe that this process is
    irreversible, but I am sure that " The energy conservation law"
    is universal law and it must be correct also for thermodynamic
    process. So, how can I save this law ?
    Probably, in the thermodynamic process there is something
    that we don't know. Maybe, there is some degradation
    of the total energy in the system which never disappears .
    Perhaps, there is some non-useful heat, some unseen process ,
    some unknown dark energy , some another form of potential
    energy/heat itself which can transform heat from the cold
    body to the warm one. I will call this conception as " entropy"
    and as it is not a law I take it as " The second principle
    of thermodynamics " which says that " the entropy of an isolated
    system always increases ". Another version: " No process is possible
    in which the only result is the transfer of heat from a hotter to a
    colder body. It is possible some reversible process which is
    unknown now ."
    Between 1870 - 1880 Ludwig Boltzmann said:
    " Clausius is right. But I can add more to his entropy conception.
    According to Classic physics when an isolated thermodynamic
    system comes to a thermal equilibrium all particles stop their
    moving. From one hand it is correct. But the system cannot be
    at thermal equilibrium (in the state of death) all the time.
    The situation in the system must change.
    Therefore I say that at the thermal equilibrium the entropy
    (some unknown dark/potential energy ) of the system will
    reach maximum and as a result , the thermal equilibrium
    of the system will change.
    I don't know how exactly the thermal equilibrium of the system
    changes. But I can give probabilistic / statistical interpretation
    of this changing process. I can write " The second principle of
    thermodynamics" by a formula: S= k log W and this formula
    says:" the entropy of the system is the collective result of
    mechanical motions of all the particles (k)."
    I will call it as " The second law of Thermodynamics."
    In 1900 Max Planck said:
    Clausius and Boltzmann are both right.
    But all my life I worked almost exclusively on problems
    related to thermodynamics. And I am sure that the " The second
    law of Thermodynamics" , concerning entropy, is deeper and it
    says more than is generally accepted. I am sure the Boltzmann's
    probabilistic /statistical version of "The second law of
    Thermodynamics " is not completed, is not final.
    Please, look at the graph of the radiation curves of the " black body".
    They are very similar to those curves which are calculated
    by Maxwell for the velocity (i.e. energy) distribution of gas
    molecules in a closed container. Could this black body radiation
    problem be studied in the same way as Maxwell's ideal gas....
    ...electromagnetic waves ? This problem of connection between
    radiation of black body and Maxwell's Electrodynamics theory
    doesn't give me peace. Maxwell's theory can tell everything
    about the emission, absorption and propagation of the radiation,
    but nothing about the energy distribution at thermal
    equilibrium. What to do? How to be ?
    After trying every possible approach using traditional
    classical applications of the laws of thermodynamics
    I was desperated. And I was forced to consider that the
    relation between entropy, Boltzmann's probability version
    and Maxwell's theory is possible to solve by suggestion ,
    that energy is radiated and absorbed with discrete
    individual quanta particle (E= hv). So, now I must write
    " The second law of Thermodynamics " by formula:
    hv = k log W.
    But I was so surprised and sceptical of such interpretation the
    entropy that I spent years trying to explain this result
    in another , less revolutionary way. It was difficult for me
    to accept this formula and to understand it essence .
    It was hard for me to believe in my own discovery.
    My conclusion.
    How to understand this formula?
    Which process does formula (hv = k logW ) describe ?
    In 1877 Boltzmann suggested that the energy/mass state
    of a physical system (of ideal gas ) could be discreted.
    This idea was written with formula: R/N=k. It means:
    there are particles with energy/mass state (k) in physical
    system of ideal gas . They dont move, they are in the
    state of rest.
    In 1900 Planck followed Boltzmann's method of dividing.
    Planck suggested that energy was radiated and absorbed
    with discrete "energy elements" - " quantum of energy"-
    - " Planck's action constant"- (h) . Its energy is: E=hv.
    In which reference frame does this process take place?
    In thermodynamical reference frame of ideal gas and
    black body (Laue called this model as Kirchhoff,s vacuum).
    Now it is considered that these models are abstract ones which
    do not exist in nature. On my opinion these models explain
    the situation in the real Vacuum (T=0K) very well.
    For my opinion the formula (hv = k logW ) says:
    The reason of " entropy" , the source of thermal equilibrium's
    fluctuation , the source of Vacuum fluctuation is an action of
    the particle /electron, which has energy: E = hv.
    The process of Vacuum fluctuation depends on collective
    motions of all particles (k) and will be successful if enough
    statistical quantity of Boltzmann's particles ( k logW)
    surround the electron.
    Which process does the formula (hv = k logW ) say about ?
    This formula explains the beginning conditions of gravitation,
    the beginning conditions of star formation.
    ( The article of star formation is posted on this site.)
    One physicist said :" The entropy is only a shadow of energy“.
    Maybe now somebody can understand why entropy is a shadow.
    And maybe now somebody will understand why
    " The Law of conservation and transformation of energy"
    is also correct for thermodynamic system.
    It took me only two months to write this brief article.
    Plus about three years searching for the key of entropy problem.
    Plus about twenty-three years trying to understand the essence
    of physical laws and formulas.
    Best wishes.