Brainy Quote of the Day

Monday, July 27, 2015

Weyl Fermions...

The surface of the double-gyroid photonic crystal used by Marin Soljačić and colleagues. A US dime is shown for scale. (Courtesy: Ling Lu)
Topics: Consumer Electronics, Particle Physics, Photonics, Quantum Computer, Theoretical Physics

Evidence for the existence of particles called Weyl fermions in two very different solid materials has been found by three independent groups of physicists. First predicted in 1929, Weyl fermions also have unique properties that could make them useful for creating high-speed electronic circuits and quantum computers.

In 1928 Paul Dirac derived his eponymous equation, which describes the physics of spin-1/2 fundamental particles called fermions. For particles with charge and mass, he found that the Dirac equation predicts the existence of the electron and its antiparticle the positron, the latter being discovered in 1932.

However, there are other solutions of the Dirac equation that suggest the existence of more exotic particles than the familiar electron. In 1937 Ettore Majorana discovered a solution of the equation that describes a neutral particle that is its own antiparticle: the Majorana fermion. Although there is no evidence that Majorana fermions exist as fundamental particles, Majorana-like collective excitations (or quasiparticles) have been detected in condensed-matter systems. Another solution of the Dirac equation – this time for massless particles – was derived in 1929 by the German mathematician Hermann Weyl. For some time it was thought that neutrinos were Weyl fermions, but now it looks almost certain that neutrinos have mass and are therefore not Weyl particles.

Now, a group headed by Zahid Hasan at Princeton University has found evidence that Weyl fermions exist as quasiparticles – collective excitations of electrons – in the semimetal tanatalum arsenide (TaAs).

Physics World: Weyl fermions are spotted at long last, Hamish Johnston

Friday, July 24, 2015

Existence...

Topics: Astrobiology, Biology, Existentialism, Philosophy, Science, Research


Note: This is a series by Quanta Magazine titled "In Theory." Though intriguing, I almost hesitated because of the title. However, the theoretical discipline has been misunderstood and caricatured by self-described "Google professors"; pseudoscience and conspiracy provocateurs. I prefer that term (provocateurs) to "theorist" for that reason. All theories are eventually proven or disproved by experimental scientists, not opinions, cognitive dissonance, revelation, visions, hunches, hoopla or mumbo-jumbo.

About Quanta Magazine:

Quanta Magazine is an editorially independent online publication launched by the Simons Foundation to enhance public understanding of science. Why Quanta? Albert Einstein called photons “quanta of light.” Our goal is to “illuminate science.”

Our reporters focus on developments in mathematics, theoretical physics, theoretical computer science and the basic life sciences. The best traditional news organizations provide excellent reporting on developments in health, medicine, technology and engineering. We strive to complement and augment existing media coverage, not compete with it.

Thursday, July 23, 2015

Earth 2.0...

The artistic concept shows NASA's planet-hunting Kepler spacecraft operating in a new mission profile called K2. Using publicly available data, astronomers may have confirmed K2's first discovery of star with more than one planet. Image Credit: NASA Ames/JPL-Caltech/T Pyle
Topics: Astronomy, Astrophysics, Climate Change, Exoplanets, Kepler Telescope, Planetary Science, Space Exploration

There's an announcement coming out today at 12 noon EST. True to form, IFLS and Hopes and Fears have given their usual breathless hyperbole. I don't know if it's "another Earth," or even if it matters. Since our fastest propulsion gets us to Pluto in ~ nine years, we currently don't have a spare hyper/warp drive to get us there in current human lifespans, though Monday's post is a good step in the interplanetary direction. Climate change is a slow-mo existential train wreck, and despite warnings by the Pentagon no less, we can't seem to get our leaders to act on: I fear we're already out of options. I don't plan to be here in fifty years when Greenland's ice sheet disappears, and Florida's coasts are under water. Neither of our presidential candidates, some of whom and their constituents are apparently willing to debate the Pope, but not science publicly.  I'd rather, take care of the planet we're on as the expense would bankrupt the global economy; such an enterprise (pun intended) would take generations, not weeks.

NASA will host a news teleconference at 9 a.m. PDT (noon EDT) Thursday, July 23, to announce new discoveries made by its planet-hunting mission, the Kepler Space Telescope.

The first exoplanet orbiting another star like our sun was discovered in 1995. Exoplanets, especially small Earth-size worlds, belonged within the realm of science fiction just 21 years ago. Today, and thousands of discoveries later, astronomers are on the cusp of finding something people have dreamed about for thousands of years -- another Earth.

The teleconference audio and visuals will be streamed live at:


JPL: NASA Hosts Media Telecon About Latest Kepler Discoveries

Wednesday, July 22, 2015

Smooth Operator...

Illustration of the programmable photonic circuit. Photons enter from the left, are processed and exit to the right. The connector at the centre top of the circuit is to the external control system. (Courtesy: Jacques Carolan et al./Science).
Topics: Consumer Electronics, Electrical Engineering, Nanotechnology, Optics, Photonics, Quantum Computer, Semiconductor Technology

Note: "Smooth operator" is in the link title of the above photo in the article. No insult or creative infringement to Helen Folasade Adu (the singer Sade) was intended.

A group of physicists in the UK has made a programmable photonic circuit that can be used to carry out any kind of linear optics operation. The researchers say that the device provides experimental proof of a long-standing theory in quantum information, and could help speed the development of photonic quantum computers, as well as establishing whether quantum computers are fundamentally different from their classical counterparts.

The research builds on work carried out back in 1897 by German mathematician Adolf Hurwitz, who showed how a matrix of complex numbers known as a unitary operator can be built up from smaller 2 × 2 matrices. A unitary operator provides a mathematical description of a linear optical circuit. This is any circuit that uses fairly standard optical components – such as mirrors, half-silvered mirrors and phase shifters – to route photons and cause them to interfere with one other. The operator has as many rows as there are output ports in the circuit and as many columns as there are input ports. With only one photon in the circuit, the probability that it travels from a particular input to a particular output is given by the square of the corresponding matrix entry.

Physics World: Physicists build universal optics chip, Edwin Cartlidge

Tuesday, July 21, 2015

The Scalpel and Rosie...

Image Source: da Vinci Robotic Surgery
Topics: Applied Physics, Biology, Computer Science, Medical Physics, Robotics

The paper describes the usage of robotics for minimally invasive surgery in mostly urology and gynecology; in my case it was sinus surgery. The 144 deaths out of 10,624 (1.4%) robotic surgeries is only small to the statisticians, not the families. I am not against these surgeries (and, if your medical provider is has experience in it, please go with their expertise and judgment), just that we obviously have a few kinks to work out yet. Even though my last thought before surgery was "this looks like Star Trek," I think we're still a few years away from Starfleet Medical.

TECHNOLOGY REVIEW: Robotic surgeons were involved in the deaths of 144 people between 2000 and 2013, according to records kept by the U.S. Food and Drug Administration. And some forms of robotic surgery are much riskier than others: the death rate for head, neck, and cardiothoracic surgery is almost 10 times higher than for other forms of surgery.

Robotic surgery has increased dramatically in recent years. Between 2007 and 2013, patients underwent more than 1.7 million robotic procedures in the U.S., the vast majority of them performed in gynecology and urology. “Yet no comprehensive study of the safety and reliability of surgical robots has been performed,” say Jai Raman at the Rush University Medical Center in Chicago and a few pals.

Physics arXiv:
Adverse Events in Robotic Surgery: A Retrospective Study of 14 Years of FDA Data
Homa Alemzadeh, Ravishankar K. Iyer, Zbigniew Kalbarczyk, Nancy Leveson, Jaishankar Raman

Monday, July 20, 2015

On A Roll...

Image Source: Science Alert
Topics: Boeing, Lasers, Nuclear Fusion, Plasma Physics, Star Trek, Star Wars

Earlier this year, Boeing patented a force field. Now, companies pursue patents largely for protection of intellectual property, but these pursuits have been legitimate good press beyond just the occasional TV commercial that blurs by in 30 seconds or so. If it works (the force field), it would only be good at this time for jeeps on the ground in conflicts that involve Improvised Explosive Devices (IEDs). This fusion jet would change the game of propulsion terrestrially as well as for interplanetary travel. Like the previous patent filing, this is just a concept at the moment.

This is another neat idea that brings fusion propulsion a little closer. I don't think we'll be breaking the champagne bottles christening Utopia Planitia shipyards just yet.

Last week, the US Patent and Trademark Office approved an application from Boeing’s Robert Budica, James Herzberg, and Frank Chandler for a laser-and-nuclear driven aeroplane engine.

Boeing’s newly-patented engine provides thrust in a very different and rather novel manner. According to the patent filing, the laser engine may also be used to power rockets, missiles, and even spacecraft.

As of now, the engine lives only in patent documents. The technology is so out-there, that it’s unclear if anyone will ever build it.

Science Alert:
Boeing just patented a jet engine powered by lasers and nuclear explosions
Benjamin Zhang, Business Insider

Friday, July 17, 2015

Our Loss, the Universe's Gain...

Claudia Alexander (1959–2015)
Topics: Comets, Diversity, Diversity in Science, Rosetta, Space Exploration, STEM, Women in Science

As a research scientist, she inspired a generation, especially young women, to seek careers in science, technology, engineering and math.

This weekend was one of great excitement for the planetary science community as the New Horizons spacecraft moved in on Pluto following decades of hard work. But that optimism took on a somber tone Saturday as news quickly traveled that pioneering scientist Claudia Alexander had died at age 56. Friends and family writing online tributes reported she suffered from breast cancer, but no official cause of death was given.

Alexander was an employee of the Jet Propulsion Laboratory (JPL) and the final project manager for NASA’s Galileo mission. But her public profile rose dramatically last fall due to her duties as project scientist for NASA’s role in the European Space Agency’s Rosetta mission to Comet 67P/Churyumov-Gerasimenko.

"The passing of Claudia Alexander reminds us of how fragile we are as humans but also as scientists how lucky we are to be part of planetary science,” James Green, director of NASA's Planetary Science Division, said in a statement. “She and I constantly talked about comets. Comet Churyumov-Gerasimenko in particular. She was an absolute delight to be with and always had a huge engaging smile when I saw her. It was easy to see that she loved what she was doing. We lost a fantastic colleague and great friend. I will miss her."

Astronomy: Pioneering Rosetta mission scientist Claudia Alexander dead at 56, Eric Betz