The best of 2006
Dec 22, 2006
It was the year that water flowed on Mars and the first cloak of invisibility was unveiled. Physicists also made important advances in the manipulation of materials at the quantum level in 2006, furthering our knowledge of the fundamental properties of matter and bringing futuristic technologies like quantum computers closer to reality.
1. January: Light and atoms get entangled
2. February: Great balls of lightning
3. March: Hurricane intensity linked to warmer oceans
4. April: Fermilab probes matter-antimatter transitions
5. May: Quantum gases in 3D
6. June: A fresh look at glass
7. July: New look for graphene
8. August: World's most creative physicist revealed
9. September: BECs confound at higher temperatures
10. October: Invisibility cloak unveiled in the US
11. November: Spin measured without destruction
12. December: Water flows on Mars
The year got off to a good start for quantum computation with two research groups reporting breakthroughs in the entanglement of atoms and light. Entanglement is a cornerstone of quantum information theory and could lead to quantum computers that outperform the machines of today. Unfortunately, entangled states tend to be much too fragile and short-lived to be of any practical use – but these results show that real progress has been made in 2006.
Is ball lightning a spectacular natural phenomenon or pure folklore? Physicists in Israel addressed this pressing issue by using a modified microwave oven to simulate how conventional lightning strikes are believed to create ball lightning. They managed to generate glowing fireballs that were described as “hot jellyfish, quivering and buoyant in the air”.
The devastation wrought in 2005 by Katrina and other intense storms in the North-Atlantic basin focused the world’s attention on the possible link between increased hurricane intensity and global warming. In March leading climate physicists raised the warning that rising sea-surface temperatures are increasing the frequency of very intense hurricanes and tropical cyclones worldwide. Thanks to an el Niño event in the Pacific Ocean, 2006 was a relatively quiet storm season in the North Atlantic -- but there could be worse to come if temperatures keep rising.
There is much more matter than anti-matter in the Universe and cosmologists explain this asymmetry by invoking a phenomenon called charge-parity (CP) violation. In March, the international CDF collaboration at Fermilab made the most precise measurement to date of the extremely rapid transitions between matter and antimatter, providing a new system in which to study CP violation. In the experiment, certain B mesons were observed to spontaneously turn into their own antiparticle equivalents -- anti-B mesons -- and back again at a rate of three trillion times per second.
Optical lattices -- which user laser beams to trap atoms in regular arrays -- allow physicists to study quantum phenomena in "labs-on-a-chip" in which almost all aspects of the interactions between the atoms can be manipulated to great precision. In May two independent teams of physicists managed to trap bosons and fermions together in a 3D optical lattice for the first time. The breakthrough should provide a model system in which to study interactions in real-life solid materials – particularly interactions between electrons and phonons, which are fermions and bosons respectively.
Glass is perhaps most enigmatic of all everyday materials and its seemingly contradictory physical properties defy simple material classifications like "liquid" or "solid". In June researchers in the US reported that glass can return completely to its original state after being bombarded with high-energy electrons. This high level of thermodynamic stability was completely unexpected given the disordered atomic structure of glass. The result is good news for those charged with disposing of nuclear waste -- who could soon be entombing radioactive materials in “self-healing” glass.
If Physics Web gave awards for “Most popular material of the year”, the 2006 prize would go to graphene, which is a two-dimensional sheet of carbon that is just one atom thick. Graphene was first made in 2004 and since then physicists have scrambled to be the first to report on its many unique properties. Early incarnations of graphene were extremely fragile flakes that were difficult to manipulate, but in July researchers in the US unveiled a new technique for making graphene by embedding it in a sturdy polymer matrix. This could open the door to transistors and other circuits that exploit the two-dimensional properties of graphene’s conduction electrons.
He’s an outspoken critic of particle physics, the scourge of string theorists and he’s won a Nobel Prize – now the condensed-matter theorist Philip Anderson has been declared the most creative physicist in the world. This was the conclusion of José Soler, a statistical physicist at the University of Madrid, who developed a "creativity index" based on the impact of scientific research papers. Particle theorist Steven Weinberg -- another Nobel laureate -- was the second most creative physicist, followed by in third place by string theorist Ed Witten. All three researchers have links to Princeton University and Physics Web can now declare New Jersey the most creative place for physics.
Bose-Einstein condensation hit the headlines in October when two separate teams claimed to have produced Bose-Einstein condensates (BECs) at much higher temperatures than has previously been possible. BECs are systems in which large numbers of bosons collapse into the same ground state as their temperature drops to near absolute zero. Now, one team says they have created a BEC at 19 K, while the other claims to have witnessed the phenomenon at room temperature – but some are asking if these systems can really be classified as BECs.
The invisibility cloak passed from science fiction to science fact in October when researchers in the US unveiled a device that can make an object almost invisible to the microwave radiation used in some radar systems. The cloak is based on metamaterials designed by the physicist John Pendry of Imperial College and it bends microwave radiation around the object, like water flowing around a smooth stone. Metamaterials allow physicists to push Maxwell’s equations beyond the limits of conventional materials to create devices with novel – and potentially useful – electromagnetic properties such as negative indices of refraction.
Physicists have long dreamed of building practical electronic circuits that can exploit the spin of the electron. This prospect is particularly tantalizing at the single-electron level, where the quantum nature of spin could be harnessed in quantum computers to achieve the parallel processing of information on a massive scale. However, success hinges on being able to read the spin state without destroying the state – something that is very difficult to do in the quantum world. Now, physicists in the US have used a laser to make the first such measurement – perhaps opening the door to systems that use the quantum properties of single electrons and photons to process and transmit information.
While it is unlikely to be raining on Mars at the moment, there is a good chance that water is flowing somewhere on the planet. This is the claim of US-based researchers who in December presented the first convincing evidence of recent alluvial activity on Mars. The researchers monitored images of the planet’s surface taken by NASA’s Mars Global Surveyor spacecraft and spotted telltale signs that liquid water had flowed in two different places in the last seven years. This is guaranteed to fuel speculation about the possibility of life existing on Mars
About the author
Hamish Johnston is editor of Physics Web.