Friday, May 26, 2006

Physics NewsUpdate - May 26, 2006. The Misshapen Solar System and Counting Terahertz Photons

The American Institute of Physics Bulletin of Physics News
Number 778 May 26, 2006 by Phillip F. Schewe, Ben Stein,
and Davide Castelvecchi

THE MISSHAPEN SOLAR SYSTEM. Having traveled far beyond the planets
in their 28.5-year journey, the two Voyager spacecraft are providing
new information on the heliosphere, the teardrop-shaped bubble that
separates the solar system from interstellar space. At this week's
Joint Assembly Meeting in Baltimore of the American Geophysical
Union (AGU) and several other geophysics-related societies, Ed Stone
of Caltech reported that the heliosphere is deformed, according to
Voyager observations, with the teardrop's rounded edge bulging at
the top (the northern hemisphere of the solar system) and squashed
at the bottom (the southern hemisphere). (See pictures and movies at
) As Rob Decker of Johns Hopkins University Applied Physics
Laboratory explained, the asymmetry is due to a magnetic field from
interstellar space pushing on the southern hemisphere. The field is
about 1/100,000 the strength of Earth's field but its effects can be
felt for billions of miles, since it is acting over a large area on
the very dilute gas at the solar system's edge.
The interstellar field even squashes an important spherical zone
inside the heliosphere, called the termination shock. Analogous to
the circle that forms when water splatters on a sink, the
termination shock represents the boundary at which the rapidly
traveling solar wind (the stream of charged gas from the sun) slows
down abruptly and piles up. Voyager 2's measurements indicate that
the southern part of the termination sphere might be a billion miles
closer to the sun than the northern part. Moreover, forces from the
solar wind cause the termination shock to breathe in and out roughly
every dozen years. Voyager 1 has already ventured beyond the
termination shock, to the heliosheath, the region where solar wind
and interstellar gas mix. So in a way, the end of the solar system
is not clearly defined. Stone guesses it could be another 10 years
(3-4 billion miles) before the two spacecraft pass through the
heliopause (the very outermost boundary of the heliosphere) and
enter purely interstellar space. The spacecraft have about another
15 years of power left in them. (Session SH02 at meeting; see

COUNTING TERAHERTZ PHOTONS. Scientists at the University of Tokyo
and the Japan Science and Technology Corporation have been able to
detect single photons in the terahertz region of the electromagnetic
spectrum for the first time. Previously, such photons, with
energies around 4 milli-electron-volts, could not be seen singly.
THz radiation, essentially in the far-infrared, is a potentially
important telecommunications carrier. Not only detection but
microscopy at ultra-low THz light levels can be performed. By
scanning a quantum-dot probe (highly sensitive to THz light) across
the face of a sample, the sample can be imaged with a
spatial resolution of 50 microns (the radiation itself has a
wavelength of 132 microns). This is even more remarkable when you
consider that the power emitted from the surface being imaged is at
the level of 10^-19 watts (0.1 attowatt). Currently photon-counting
microscopy glimpses a few electrons at a time oscillating at THz
frequencies in semiconductor devices at high magnetic fields.
According to Kenji Ikushima (, the
extraordinarily high-sensitivity of the photon counting approach
will soon facilitate the study of a molecule shaking, rattling and
rolling at THz rates, photon-counting microscopy in this spectral
range will facility the study of a few molecules at a time
oscillating at THz frequencies in semiconductor devices at high
magnetic fields. (Ikushima et al., Applied Physics Letters, 10
April 2006; www.dbs.c.u-tokyo.acjp/~komiyama )

Monday, May 22, 2006

The American Institute of Physics Bulletin of Physics News
Number 777 May 18, 2006 by Phillip F. Schewe, Ben Stein,
and Davide Castelvecchi

EXTREME-ULTRAVIOLET MICROSCOPE PROVIDES RECORD RESOLUTION. At next week's Conference on Lasers and Electro-Optics/Quantum Electronics nd Laser Science Conference meeting in California, Courtney Brewer of Colorado State University ( and her colleagues will present a tabletop optical imaging system that can
reveal details smaller than 38 nanometers (billionths of a meter) in size, a world record for a compact light-based optical microscope. The microscope can keenly inspect nanometer-scale devices designed for electronics and other applications. It will also be capable of catching subtle manufacturing defects in today's ultra-miniaturized computer circuits, where defects just 50 nm in size that were once too small to cause trouble could wreak havoc in the nanometer scales
of today's computer chips. Except for some high-tech details, the microscope works very similarly to a conventional optical
microscope. Light shines through the sample of interest. The transmitted light gets collected by an "objective zone plate," which forms an image on a CCD detector, the same kind of device that records images in a digital camera. However, in the case of the sub-38-nm microscope, there are some advanced technological twists. The microscope uses a laser that
produces light in the extreme-ultraviolet (EUV) spectrum, whose very small wavelength makes it possible to see a sample's tiny details. The EUV light is created by ablating (boiling away) the surface of a silver or cadmium target material so that the vaporized material forms a plasma (collection of charged particles) that radiates laser light. To focus this light, the researchers avoid standard lenses because they strongly absorb EUV radiation. Instead, the microscope uses "diffractive zone plates," structures containing nanometer-spaced concentric rings that focus the light in the desired fashion.
Other state-of-the-art optical microscopes have achieved resolutions as low as 15 nm, but they required the use of large synchrotrons. This more compact and less expensive system has the potential to become more widely available to researchers and industry. In addition, since the extreme ultraviolet laser produces light pulses with very short duration (4 picoseconds, or trillionths of a second), the researchers believe it may be possible to create picosecond-scale snapshots of important processes in other applications. (Paper CME4,

FRICTION AT A DISTANCE, the friction between close objects that aren't in contact, is poorly understood. Seppe Kuehn and his colleagues at Cornell have set out to change this. First, what does contact mean? Kuehn (607-254-4685, suggests that when two objects are less than about 1 nanometer apart they are said to be in contact. One can think of contact friction as being a sort of micro-velcro process---atomic "hills" in one surface scrape past atomic "valleys" from the other surface. To observe non-contact friction, the friction between two surfaces separated by more than 1 nm, the Cornell researchers use a tiny single-crystal microcantilever less than a millimeter long and only a few thousands
of atoms thick. Brought vertically downwards toward a surface, and set in motion, the cantilever will slow down in proportion to the friction it feels from the surface beneath. Surprisingly, the friction force between the cantilever and sample depends on the chemistry of the sample. By studying this dependence of non-contact friction on the chemistry of the sample the Cornell scientists have made the first direct, mechanical detection of non-contact friction arising from the weak
electric fields caused by motions of molecules in the samples. The samples included various polymer materials. This work is motivated by recent efforts towards single-molecule MRI which require the detection of very small forces, and have been hindered by non-contact friction. (Kuehn, Loring, Marohn, Physical Review Letters, 21 April 2006)

Sunday, May 21, 2006

Latest PhysicsWeb Summaries


Related Resources
Physics News
Physics 101 - Basic Information

Elsewhere on the Web


Quantum gases in 3D (May 17)
Condensed matter physicists have come a step closer to their dream laboratory, with the news that two independent teams have managed to trap bosons and fermions together in a 3D optical lattice. The breakthrough provides a model system in which to study real-life solid-state materials, and may even lead to a better understanding of certain biological systems and traffic flow.

LEDs move into the ultraviolet (May 17)
Physicists in Japan have made a diode that emits light at the shortest wavelength ever. The device, made by Yoshitaka Taniyasu and colleagues at NTT Basic Research Laboratories in Atsugi, is made from aluminium nitride and emits deep in the ultraviolet part of the spectrum at 210 nanometres (Nature 441 325). The work represents an important step towards the development of very low-wavelength light emitters that could find use in a wide variety of applications, including medicine, photolithography and to destroy bacteria in contaminated water.

Magnetic fields go to the maximum (May 18)
What is the maximum possible magnetic field allowed in our universe? According to two theoretical physicists in Russia and Israel, it is 1042 Gauss -- a value that is a billion times smaller than the previous estimate for the upper limit. As well as being of fundamental interest,
the new finding -- if correct -- may rule out theories on "superconductive cosmic strings" and also some accepted mechanisms of producing other hypothetical objects such as magnetic monopoles (Phys. Rev. Lett. 96 180401).

Change of focus for liquid crystals (May 19)
Physicists in the US have created a new type of tuneable liquid-crystal lens, whose focus can be changed by varying the voltage applied to it. The new device is better than traditional liquid-crystal lenses because it only has small astigmatism and does not scatter light. It could be
used for zoom lenses and other microphotonic devices (Appl. Phys. Lett. 88 191116).


Analyze the Data and Draw Conclusions

Related Resources
Great Science Fair Projects
Conduct Your Experiment
Physics 101 - Basic Information

Elsewhere on the Web
Hundreds of Science Fair Projects for Students
Science Fair Central offers ideas for science fair projects and experiments

Once you have your data, you will make any calculations you need for the analysis. It is almost always productive to produce graphs and charts of your data to help you understand and visualize your data.

The analysis leads you to the most important question – does your data support your hypothesis?

Your conclusion is a short statement of your experiments results and how they relate to your hypothesis. Once again, don't worry if your results contradict your hypothesis – a negative result is just as interesting.

Saturday, May 20, 2006

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First of all, have a look around my site. I might have answered your problem already. If not, there are a couple of places you can look:

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About Joseph Andersen

I am a graduate student in the physics at Harvard University.
My undergraduate degree was obtained from UQ in 1999, during which I was awarded the university medal for outstanding scholarship.
I have worked in laboratories searching for gravitational waves, exploring the physics of matter at ultra low temperatures, I am currently working on Climate Simulations.
I have been involved in the UQ Science in Action Program and the UQ physics student club demonstration team – demonstrating exciting areas of physics to school and university students and the general public. I have shown five year olds how to suck water through a straw quicker than their teachers and “tamed” 3000000V lightning generated by a Tesla Coil. I taught mechanics to premed students and poured liquid nitrogen down the front of my body. I have experience at “physics for the non-physicist” while still being a practicing, published physicist in one of the premier science environments.

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Monday, May 15, 2006

Physicists Use Soap Bubbles to Study Black Holes

People use them to get cars, dishes and clothes clean. Children blow them for fun. And now, a University of Mississippi physicist thinks soap bubbles can help scientists better understand the properties of black holes.


Tuesday, May 09, 2006

Latest PhysicsWeb Summaries

Latest PhysicsWeb Summaries


Try phySpy - Wiley-VCH's new international physics portal. Featuring THE
search engine for physicists. Based on the principle of neuronal
networks, searches for and filters out just the information
you need." (link:


Physics World

Sleeping giant (May 3)
It is right that the US should increase its investment in particle

Antarctica calling (May 3)
Physicists are playing a valuable role in understanding our last great

Top papers (May 3)
In a special readers' poll Robert P Crease seeks your nominations for
the most interesting paper of all time

Antarctica unravelled (May 3)
After more than a century of polar exploration, recent satellite
measurements are painting an altogether new picture of Antarctica.
Andrew Shepherd explains how physics is helping researchers understand
the critical transformations taking place in the world's largest ice

WMAP data put cosmic inflation to the test (May 3)
Measurements of the polarization of the cosmic microwave background open
up a new window on the universe when it was just 10^-35 s old, explains
Gary Hinshaw

Mobilizing magnetic resonance (May 3)
Nuclear magnetic resonance traditionally requires large magnets that
make the technology immobile and expensive. Boyd Goodson describes how
efforts are being made to develop portable devices that will extend the
reach of this powerful imaging technique.

Sensing the extreme (May 3)
From volcano vents to the surfaces of distant planets, silicon-carbide
sensors are poised to take us into environments where we have never
measured directly before, as Alton Horsfall and Nick Wright explain



Cosmology gets precise (May 3)

The Infinite Cosmos: Questions from the Frontiers of Cosmology Joseph
Silk 2006 Oxford University Press 256pp £18.99/$29.95hb

Plotting the life of Descartes (May 3)

Descartes: The Life of René Descartes and Its Place in His Times A C
Grayling Free Press 2005 352pp £20.00hb

Shelf life: Simon Singh (May 3)
Simon Singh is an author, journalist and TV producer specializing in
science and mathematics


Monday, May 08, 2006

Latest PhysicsWeb Summaries


Veneto Nanotech Launches the 2nd Edition of Nanochallenge Enter your
nanotechnology business plan to Nanochallenge 2006 and you could win the
grand prize of Euro 300,000. The competition seeks commercially viable
business plans for innovative start-ups to produce and commercialize
products and services in the nanotechnology industry. Find out more at



No WIMPS -- only superWIMPS (Apr 25)
It will be difficult for the Large Hadron Collider at CERN, which comes
online next year, to detect "WIMPS" -- the leading dark-matter candidate
particles -- say physicists in the US. However, the collider, which will
be the world's most powerful particle accelerator, might be able to
detect a new class of particles called "SuperWIMPS" -- the decay
products of WIMPS. The detection of dark matter particles would
represent a major breakthrough in both particle physics and cosmology
(Phys. Rev. Lett. 96 151802).

US told to invest in particle physics (Apr 26)
America must boost its investment in particle physics if it is to stay
at the forefront of the discipline. That is the conclusion of a National
Academy of Sciences panel charged with recommending priorities for US
particle physics over the next 15 years. The panel believes that the
"intellectual centre of gravity" within the field is moving abroad and
that, as things stand, within a few years most American experimental
particle physicists will be working at facilities overseas.

Nuclear waste should be buried (Apr 27)
After three years of deliberation, a government-commissioned inquiry has
concluded that the UK should bury its nuclear waste deep underground.
The Committee on Radioactive Waste Management (CoRWM) laid out its
solution to the decades-old waste problem in a press conference held
today. But it told reporters that because it will take many years to
dispose of the waste in this way, the construction of a permanent
repository must be complemented by a robust system of interim storage.

Insects inspire artificial eyes (Apr 27)
Scientists in the US have made the first artificial eye using 3D polymer
structures. The eye, which is made from individual "ommatidia" -- or
single lenses -- arranged in a dome shape, is similar in structure to an
insect's compound eye. It was developed by Luke Lee and colleagues at
the University of California at Berkeley. Each ommatidium consists of a
refractive polymer microlens, a light-guiding polymer cone, and a
waveguide that together collect and direct light into an optoelectronics
detector that can recognize images. If perfected, such eyes could be
used in medicine, environmental monitoring, industry and the military
(Science 321 557).

New light on giant tilts (Apr 28)
A new theory has been proposed to explain how the giant planets --
Jupiter, Saturn and Uranus -- became tilted. The tilts of these planets
are fixed, whereas the tilts of the smaller Earth-like planets --
Mercury, Mars and Venus -- have changed with time. The new theory, which
has been developed by Adrian Brunini at the National University of La
Plata in Argentina, says that the tilts were fixed by the way the
planets interacted gravitationally as they moved from being close
together to the positions they occupy today (Nature 440 1163). If
correct, the theory would solve one of the biggest mysteries in our
solar system.


Thursday, May 04, 2006

Staggering atoms sober up in physics detox cell

Using an entirely new technology, a research team from Umeå University in Sweden has succeeded in controlling and converting energy from the random movement of atoms. “You could say that we have found a detox cell where drunken atoms can sober up,” says physicist Peder Sjölund. The findings are being published in the journal Physical Review Letters.


Physics: Thinking Back and Forward

"Physicists Contemplate Their Impact over the Last 75 Years as Their Science Expands into Diverse Frontiers

May 3, 2006--As the American Institute of Physics (AIP) celebrates its 75th anniversary this year, physicists think about how much their science has evolved and how far it has expanded into new territory. Several busy physicists have taken the time to step back from their work to reflect upon events that have transpired since that occasion in 1931 when AIP first set up shop in New York City."

In the past 75 years, breakthroughs in physics have led to life-saving medical imaging, ubiquitous computers, inexpensive worldwide telecommunications, and an ever-deepening knowledge of matter, the Earth and the universe," says Marc H. Brodsky, AIP's Executive Director and CEO.

What have been the most important events in physics during this relatively short period of time? AIP senior historian and physicist Spencer Weart suggests two discoveries which took place in the early 20th century that have had tremendous influence on how we not only see and understand our world, but also how we live in it.Quantum mechanics and Einstein’s general theory of relativity, he says, have laid down the "new physics" of our age. "