PHYSICS NEWS UPDATE
The American Institute of Physics Bulletin of Physics News      
Number 749   October 13, 2005  by Phillip F. Schewe and Ben Stein

THE CAREER OF CHARLES TOWNES, filled with outstanding accomplishments in
laser science and radio astronomy, was celebrated at a meeting held last
week at the University of California at Berkeley.  The gathering, called
"Amazing Light: Visions of Discovery," marked Townes's 90th
birthday and was the occasion for a series of talks by distinguished
speakers (18 Nobel laureates were
present) on forefront topics in fundamental physics and the technological
innovations that arise from basic research (meeting website at
http://www.foundationalquestions.net/townes/).  The following items
represent some of the interesting results and quips from the meeting.

To start with, this year's physics Nobel Prize
(http://www.aip.org/pnu/2005/split/748-1.html), announced only two days
before the start of the meeting, could not have been better aligned with
Townes's pioneering laser work and with recurrent themes expressed in
several talks, namely the ubiquity, versatility, and quantum nature of
laser light.  Two of the 2005 laureates were actually in attendance: Roy
Glauber (Harvard) and Theodor Haensch (Max Planck Institute, Munich).

Haensch sounded an important precept by quoting Townes' former colleague,
Arthur Schawlow: "Never measure anything but frequency," meaning
that signal frequency can essentially be measured with higher precision
than any other physical quantity.  For example, the frequency of light cast
off by the hydrogen atom in relaxing from its first excited state to its
ground state is known with an uncertainty of better than one part in 10^14.
 Haensch said that this precision will improve further in coming years,
with a corresponding improvement in things like spectroscopy and readouts
from the Global Positioning System, an excellent example of turning a
distance measurement into a frequency measurement.

Who will be the next Charles Townes?  We don't know, but to encourage and
recognize newcomers, a young scholars competition was held at the meeting. 
In the technological innovation category, the first place award went to Jun
Ye, a JILA/NIST colleague of another of this year's Nobelists, John Hall. 
Ye also spoke about the superb optical precision made possible by the
advent of femtosecond laser pulses.  He reported on JILA/NIST's efforts to
produce a highly precise, stable laser output and its applications to
various scientific endeavors. Combining ultracold atoms, stable lasers, and
coherent control techniques, the JILA team is making advances in several
areas including the work on an optical atomic clock, where measurement
precision has reached a level of about 7 x10^-15. The precise measurement
is made possible by a primary frequency standard, NIST's fountain cesium
atomic clock, which is accurate to
7 parts in 10^15.
                
What will be the next great invention on the order of the laser?  We don't
know, but clever new ideas keep coming along.  The second-place award in
the technological innovation competition went to Marin Soljacic (MIT) for
his concept of wireless, non-radiative energy transmission. Just as in the
quantum case in which the Schrodinger equation allows for a wave trapped in
a box to tunnel out, so Maxwell's equations allow for the leakage of
electromagnetic energy from an electromagnetic resonance object.  If
another such object were placed not far from the first one, and the
resonant frequencies of both were the same, then the energy could be
transferred between them with very little energy lost to other objects in
the nearby environmental that do not share the same resonant frequency. 
The transmitted energy, although electromagnetic in nature, would not be
referred to as "radiation"
since it is bound to the resonant objects.  It is rather an example of
"near-field" physics.  Soljacic avoids words like
"antenna," since the process does not involve broadcasts of
energy in the usual sense.  In contrast, the vast majority of energy
radiated by antennas is typically wasted and lost into free space, while
only a small portion is picked up by the eventual receivers.  Instead,
Soljacic uses terms like "source" and "drain" in
analogy with transistors to describe the movement of energy.  An exemplary
setup might consist of a transmitter in a ceiling and devices in that room
(e.g robots, or computers) being powered wirelessly by this energy.  (For a
list of other young scholar winners, see
http://www.foundationalquestions.net/townes/pressroom.asp)

Steven Chu (LBL), speaking of measurements made in the biological physics
realm, said that Isaac Newton's worldview applied largely to a frictionless
world.  If Newton had been the size of a bacterium, Chu suggested, the
famous force laws would we very different: (1) an object in motion will
very shortly come to a rest; (2) an object nominally at rest will jiggle
around a lot; and (3) the force an object feels is proportional to surface
area and velocity.

Wolfgang Ketterle (MIT), speaking of trapped vapors at nano-kelvin
temperatures, said that unlike the early history of the study of coherent
light in the 1960s, the current study of coherent matter (atoms held in
static BEC clouds or released as "atom laser" beams) was not a
"solution in search of a problem."  BEC-based matter-wave
sensors, he said, would most likely find useful applications in geology (as
gravity sensors) and in navigation (rotation sensors).  Furthermore,
molecular BECs made from paired fermi atoms and partaking of strong tunable
interactions, would likely serve as an arena for studying two of the most
important issues in all of condensed matter physics, high-temperature
superconductivity and the quantum properties of spin liquids (ensembles of
magnetic particles).

Anthony Leggett (Univ Illinois) addressed one of the meeting's
principal themes, grappling with quantum reality.   We don't really
know the past, Leggett asserted.  Our knowledge of macroscopic matter is
"thermodynamic" (meaning that what we know pertains to averages
over large numbers of particles) and not microscopic.  Quantum uncertainty
and chaotic dynamics are also often invoked in denying the realization of
longterm predictability.  Therefore we could never, as Pierre-Simon Laplace
held, employ deterministic equations to calculate the subsequent extended
history of the universe.   (The issues of causality, the knowability of the
past, and of free will came up in several talks at the meeting.)

Where will science go next?  We don't know, but Peter Galison (Harvard)
spoke of the intellectual climate in which past technological and
scientific discoveries have been made.  He sees the historical and
philosophical view of physics over the past century or so as oscillating
between two poles---the positivist view (typified by Ernst Mach), according
to which only experimental observations are considered satisfactory and
reliable, and the anti-positivist view (typified by Thomas Kuhn), which is
much more willing to credit theoretical ideas in advancing and altering the
general consensus.  Meanwhile, Freeman Dyson (Institute for Advanced Study)
carved up physics history in a different way.  Borrowing Isaiah Berlin's
famous dichotomy between "foxes" (which know many things) and
"hedgehogs" (which know one big thing), Dyson said that the great
hedgehogs and foxes of physics seemed to come in waves.  Einstein and
Newton, said Dyson, were hedgehogs; they're the deep thinkers.  Enrico
Fermi, and the guest of honor, Charles Townes, were foxes; with agility
they moved from topic to topic.  Dyson's nominal topic was the future of
science.  He claimed no method for predicting coming achievements. 
"The best way to learn about the future of science," he concluded
in his elegantly gruff manner, "is to stay alive as long as you can
and see what happens."

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