Reginald L. Goodwin's Posts

For Eleanor...

Posted by Reginald L. Goodwin on June 10, 2016 at 5:20am

OSA sponsors multiple programs to promote optics and photonics among K-12 students.

Legacy programs include the Optics Discovery Kit and the Optics Suitcase. Online, OSA sponsors the Optics4Kids site which provides information and educational resources. (iStock.com$#92;VYCHEGZHANINA)

(Courtesy of iStock.com\VYCHEGZHANINA)*

Topics: Diversity in Science, Einstein, Electromagnetism, James Clerk Maxwell, Laser, Modern Physics, Optics, Quantum Mechanics, Women in Science

"It is better to light a candle than curse the darkness." Eleanor Roosevelt

In June 1916, exactly one century ago, Albert Einstein predicted the existence of ripples, known as gravitational waves, in the fabric of spacetime. Earlier this year we celebrated the stunning observation of the phenomenon by a worldwide collaboration of more than 1000 scientists using incredibly sensitive antennas built of mirrors and lasers. (See Physics Today, April 2016, page 14.) As with many scientific achievements, this recent milestone draws on innumerable theoretical, observational, and technological innovations and iterations made along the way. It’s worth reflecting on the vast body of knowledge the scientific community has generated, the breakthrough technologies that have allowed us to observe our world with ever-greater depth and precision, and the people who have dedicated their lives and careers to expanding knowledge and applications in diverse branches of science.

This year marks the 100th anniversary of The Optical Society, a worldwide community for optics and photonics professionals and students. Over the past century, the research world and consumers alike enjoyed a dramatic expansion of light-based science and applied technology. In many ways, the growth of optics and photonics has mirrored the birth and expansion of modern physics from the early 20th century through today. Applied optics and spectroscopy have long played a central role in enabling new discoveries in physics; that new physics has fueled advances in optics and photonics that, in turn, have created powerful tools for the study of space, time, and matter. The laser, for instance, has become an indispensable tool of scientific inquiry. Solid-state detectors of incredible density and sensitivity are used for scientific imaging from telescopes on Earth to cameras on Mars. Innovations in laser cooling have given us unprecedented access to the quantum world, and laser frequency comb technology has greatly expanded precision measurements for both fundamental and applied sciences.

But that list is far from complete. This article permits only a sparse survey of the noteworthy advances and trailblazers from the past century of optics and of the innumerable benefits we derive from them. Further highlights are available on the OSA Centennial webpage at www.osa.org/en-us/100/osa100*.

Physics Today: A century of light, Anne Frances Johnson and Nancy D. Lamontagne

Compact Radiocarbon Detector...

Posted by Reginald L. Goodwin on June 9, 2016 at 5:15am

Physics Today: Optical detection of radiocarbon dioxide (partial view)

Topics: Modern Physics, Radiation, Spectrograph

A compact spectroscopic system can measure radioactive carbon dioxide concentrations as low as five parts per quadrillion.

Carbon’s only naturally occurring radioactive isotope, ¹⁴C, is exceedingly rare. Produced when neutrons from cosmic rays interact with nitrogen, the radioisotope makes up just one part per trillion of the carbon in Earth’s atmosphere. Yet because of its continual production, its diffusion through the planet’s carbon cycle, and its long half-life of 5700 years, ¹⁴C is routinely used to date organic matter as old as 50 000 years. Archaeologists, forensic scientists, and environmental researchers, among others, essentially measure the concentration of radiocarbon in a sample to determine its age.

Since the late 1970s, accelerator mass spectrometry (AMS) has served as the benchmark method for the job. In that approach, samples are burned, chemically converted to graphite, and bombarded with cesium ions. The negative carbon ions ejected from the solid samples are then accelerated to a few percent of the speed of light and their mass-to-charge ratios deduced from their trajectories through electric and magnetic fields. Fortuitously, the most common isotope of nitrogen in the atmosphere, ¹⁴N, forms no stable negative ion; and its absence eliminates its otherwise large interference with the ¹⁴C signal. Likewise, ¹²CH₂ and ¹³CH molecules are broken apart during a later, electron-stripping stage and don’t survive to interfere with the signal.

Both effects help free ¹⁴C signals from background noise. But although the technique is powerful—and applicable to other trace elements—the spectrometers can cost millions of dollars and often require a dedicated facility to maintain their electrodes at hundreds of thousands to millions of volts in a vacuum.

A technically simpler approach also begins with burning a sample, but only to transform its carbon atoms into carbon dioxide molecules. With their strong vibrational absorptions in the mid-IR, the many isotopic combinations of CO₂ can be distinguished optically. The challenge is to measure the intensities of their spectral lines to determine the concentration ratios. The task is not easy if the goal is to count trace isotopes in a sea of abundant ones. The CO₂ molecule has hundreds of vibrational and rotational lines, many of them closely spaced in frequency. And even the most stable lasers suffer from intensity fluctuations.

Physics Today: Smaller, faster, cheaper detection of radiocarbon, R Mark Wilson

Particle X...

Posted by Reginald L. Goodwin on June 8, 2016 at 5:00am

A new type of particle could have interacted with protons and neutrons shortly after the Big Bang, so as to break up lithium-7. (Courtesy: iStockphoto/Insomnela)

Topics: Astrophysics, Big Bang, Early universe, Particle Physics, Theoretical Physics

I remember Racer X as a child, but this is just another reason to blame for our laptop batteries not holding a charge as long as we'd like.

For a little more than a decade, scientists have been struggling to explain why the amount of lithium predicted to have been formed in the early universe is about three times the value actually observed. Now, an international team of researchers believes it may have the answer: a new type of particle, outside of the Standard Model, that would have interacted with protons and neutrons shortly after the Big Bang so as to break up lithium-7.

According to a theory known as "Big Bang nucleosynthesis", protons and neutrons fused to form nuclei in the first few minutes after the Big Bang. This process generated deuterium, large amounts of helium-4 and smaller amounts of helium-3 – the latter two combined to create beryllium-7, which eventually decayed to lithium-7. The theory makes very precise predictions of the relative proportions of these nuclei, based on a quantity – known as the photon–baryon ratio – taken from observations of the cosmic microwave background.

For helium and deuterium, these predictions agree very well with observations of physical systems thought to contain material dating back to the time of the Big Bang. However, the theoretical value for lithium – just five per billion of hydrogen – is between two and five times too high.

Now, Maxim Pospelov of the Perimeter Institute in Waterloo, Canada, together with colleagues at the Austrian Academy of Sciences in Vienna, says that this mismatch is not a "full-blown crisis for cosmology" because the observed lithium-7 levels, which are obtained from atmospheric spectra of very old stars, might not match primordial values. The researchers say that obscure astrophysical processes might have depleted lithium within the stellar atmospheres, but add that astrophysicists have yet to pinpoint such a process.

Physics World: Particle 'X' may have snuffed out cosmic lithium, Edwin Cartlidge

Slingshot...

Posted by Reginald L. Goodwin on June 7, 2016 at 6:30am

Image Source: Physics Today

Topics: Astrophysics, Black Holes, Cosmology, Dark Matter, General Relativity

Shooting out of the galaxy at speeds greater than the escape velocity, hypervelocity stars provide a window on black holes and the distribution of dark matter surrounding the glowing Milky Way.

Because gravity keeps stars on their orbits, astronomers can use the motions of stars to infer the mass distribution of the visible and invisible constituents of the Milky Way. The Milky Way is the only galaxy whose visible mass distribution we can see in three dimensions and in which we can accurately measure the velocities of millions of individual stars. Gravitational accelerations in the galaxy are usually small, however. Our sun, for instance, experiences a gravitational acceleration of just 2 Å/s² as it orbits the Milky Way. That’s 10⁻¹¹ of what we experience on Earth’s surface. It’s also the gravitational- acceleration regime of dark matter—the unseen material inferred to exist in and around galaxies.

Some of the initial evidence for dark matter came in 1932 after Dutch astronomer Jan Oort developed the first modern theory of stellar motions.¹ Oort compared the velocity dispersion of stars near the Sun with their number density and inferred the existence of more mass than could be accounted for by the visible stars. In more recent times, radio astronomers have measured the rotation speeds of gas—specifically neutral hydrogen—in the outer parts of the Milky Way and other disk galaxies with much higher accuracy than could be done in Oort’s era. Intriguingly, they found that rotation speeds do not decline with increasing distance outward but stay constant. To keep galaxies like the Milky Way bound together requires the gravitational pull of dark matter, if not a modified theory of gravity.

The focus of this article is a new class of astronomical objects, known as hypervelocity stars, that uniquely connect the center of the galaxy to its outer halo. A decade ago I and my colleagues Margaret Geller, Scott Kenyon, and Michael Kurtz at the Smithsonian Astrophysical Observatory in Cambridge, Massachusetts, unexpectedly discovered a star moving away from Earth at 850 km/s, roughly 2 million miles per hour.³ The speed is astonishing: The star is racing outward with at least twice the galactic escape velocity at its distance of 300 000 light-years from the galactic center.

Physics Today: Hypervelocity stars in the Milky Way, Warren R Brown

30 Years of AFM...

Posted by Reginald L. Goodwin on June 6, 2016 at 5:00am

Source: Artificial Oxide Nanostructures: Physics of Multiscale Phenomena

Topics: Atomic Force Microscopy, Biology, Cancer, Consumer Electronics, Electrical Engineering, Nanotechnology, Semiconductor Technology

Thirty years since its first inception, the atomic force microscope has proved a hugely versatile tool. Applications range from quantifying dopant distributions in electronics and the analysis of dust particles in space, to characterizing biopsies for cancer diagnostics. More than simply bringing atomic-scale resolution to non-conducting surfaces, modifications of the technology have provided important tools for sensing chemical entities and mechanical properties, with force sensitivities so great they can be used to study and control mitosis in the proliferation of life itself. nanotechweb.org visited Basel in Switzerland, home to some of the pioneers in AFM technologies, to find out how far the field has come in the past three decades.

The development of scanning probe technologies began with the scanning tunnelling microscope (STM), and was driven by the semiconductor industry in the late 1970s. Christoph Gerber, co-inventor of the atomic force microscope, points out that although electronics feature sizes were coming close to the nanometre scale in the 1970s, there was no way of obtaining spectroscopic information of such small features. “We thought that if we established a tip very close – so that due to the proximity there would be tunnelling - we would have an instrument that could do this kind of spectroscopic work.” From there came the idea of scanning the tip and keeping the quantum tunnelling current constant. This would effectively trace a topography of the surface with a lateral resolution that could image atoms. “The big breakthrough for STM came when we were able to image the 7 × 7 reconstruction of silicon (1,1,1),” explains Gerber. As the arrangement of atoms at the surface differs from the bulk, glimpsing this reconstruction in a real image was a powerful demonstration of the instrument’s potential.

Francois Huber, who shares a lab with Hans Peter Lang, highlights how the cantilever arrays have also become useful for identifying single gene mutations from biopsies. Recently introduced cancer drugs have particularly high efficacy for specific cancer genes, such as the HER2 gene for aggressive breast cancer and the BRAF mutation found in 50% of malignant melanoma incidents. “Before we treated cancers with general chemistry or radiation – everybody got the same treatment and either you were lucky or unlucky,” says Huber. “Here we can actually target the cancer directly – it goes towards personalized medicine so that you treat patients according to their genetic predisposition.”

Nanotechweb: Atomic force microscopy – 30 years on

Feedback Loop...

Posted by Reginald L. Goodwin on June 3, 2016 at 6:01am

State-Space Equation of a Feedback Loop, Source: Wikibooks

Topics: Commentary, Education, Politics

Spoiler alert: This post has nothing to do with Control Systems Theory.

I recall reading a story in the Winston-Salem Sentinel (when we had morning and evening newspapers): about a young man, my age at the time (11-years-old). His parents motivated him by paying $10 for every “A” he made. One semester, he made a “B.” To teach him a lesson – the article reported – his parents paid him nothing on any of the other A grades. He promptly – or, sometime during that day – went out to their barn and tragically used his family's shotgun. I would get older...he would not.

When I first attended NC A&T State University, like most freshmen, I was in love with someone who wasn’t on campus (she was a high school senior). Looking back, our difference in age and maturity should have made me immediately end the relationship on my getting to campus. I initially majored in Engineering Mathematics, knowing I wanted to be in a STEM field, but not quite committing to Electrical, Mechanical or Industrial Engineering (as I look back, I’m not quite sure why).

My first semester ended with average grades, but my relationship back in Winston-Salem got harder to manage. I thought more frequent visits would heal our divide that kept getting wider. To make a long story short: I achieved four “Fs” for my trouble, and got placed on academic probation. My father – after our breakup – gave me a stark choice: get it together, or go in the military. (I did eventually on graduation, but as an officer in the Air Force.)

I met Dr. Tom Sandin purely by chance in front of Marteena Hall as I pondered my father’s ultimatum. Dr. Sandin was funny and affable, and suggested I not quit, but instead “try physics.” Physics, I thought? What evidence do I have now that I’m even good enough to complete a degree, let alone increase the complexity of my matriculation? Tom Sandin insisted, and I changed my major from Engineering Mathematics to Engineering Physics. It was encouragement, but that was enough. That's not to say Tom Sandin was an easy teacher! I got many a low grade with the note "see the answer" that he posted after every homework or quiz in the Library Mezzanine. I worked hard, sacrificing Fridays, weekends and summers my peers used to work internships for summer school courses; every summer until I graduated. I gradually pushed my GPA to a 3.0 (the four Fs prior dragging down my overall). I made the dean’s list a few times. I found out later to my delight, that Dr. Sandin also taught a personal hero of mine, Dr. Ron McNair, the first black astronaut from a HBCU; I met him in Greensboro when my Air Force ROTC detachment honored his maiden voyage into space. I was emotionally saddened by the Challenger Disaster.

Failure is feedback. Sometimes the thought of failure - earned or unfair - in life can be a great motivator and filter of what you will and will not do.

I called Ron McNair before his final mission, December of 1985. He revealed to me that someone at MIT sabotaged his research five weeks before his PhD dissertation, considering the times, likely due to jealousy and racism. He didn't let that stop him. He re-accomplished five years of research in three weeks time. He did not sleep until he had completed his oral defense. After that, Dr. McNair (officially) slept for a week.

I can’t help but thinking what happened at UCLA is a reflection on the society we’ve created. Millennials are joked about, parodied, etc. I recall, and know most martial arts organization, soccer, T-ball and extracurricular activities give participation medals (see the parody). Charlie Brown would strive every summer to win a baseball game; he would strive mightily to kick the football before Lucy pulled it away: he never did it. We understood it was Charles Schultz's camp humor that made the gag work every time, but it was an object lesson: it showed perseverance, that you don't have to start out "perfect" and always be perfect to be successful. Unlike Charlie Brown, we can learn and grow from our mistakes.

What happened at UCLA could be any campus USA. It’s similar to what happened in Aurora, Colorado when James Holmes killed twelve people and wounded several others: he’d failed his qualifier in graduate school for Neurosciences. Holmes - as someone who’d likely never received a failing grade in his life, freaked. He never fell in love and failed four subjects; no one sabotaged his research due to his cultural ancestry. I’m sure this man who killed his engineering professor in California (and apparently had a "kill list" of additional offenders) had a similar, privileged pedigree. Unlike Holmes, he apparently achieved a PhD. Also unlike Holmes: because of his name, cultural background, ethnicity and the volatile election cycle, he didn't do us any favors in a clearly fractured nation, split by crassly manipulated bigotry for political gain.

Life will be challenging and disappointing, academically, personally and professionally. What distinguishes achievers from others is being willing to learn from mistakes and grow better from them. Violent tantrums – especially the lethal kind – serve no purpose, other than brief sensationalism... and oblivion. A personal Armageddon is not a reward, nor a victory. It is as this essay began and always will be: tragic.

Pluto's Polygons...

Posted by Reginald L. Goodwin on June 2, 2016 at 4:52am

Sputnik Planum on the surface of Pluto, as seen by the New Horizons spacecraft. Several polygons are visible in the image. (Courtesy: NASA/JHUAPL/SwRI)

Topics: NASA, Planetary Science, Pluto, Space Exploration

The patchwork of polygons on the surface of a vast plain of ice on Pluto is created by heat upwelling from the interior of the dwarf planet. That is the conclusion of two independent teams of scientists that have combined data from NASA's New Horizons mission with computer simulations to gain a better understanding of Sputnik Planum – the flat region where the mysterious polygons exist. One important consequence of the convection process is that the surface of Sputnik Planum could be less than one million years old, making it one of the newest known surfaces in the solar system.

NASA's New Horizons spacecraft reached Pluto in July 2015, making it the first mission to explore the dwarf planet. The spacecraft has since provided scientists with a wealth of information about Pluto and its moons as well as the first images of Pluto's icy surface, which captured the imagination of scientists and the public alike.

Sputnik Planum, which is an ice-filled basin that occupies an area of about 900,000 km², makes for a particularly interesting feature. The surface of the ice – which is believed to be mainly nitrogen – appears to be broken up into a collection of polygon-shaped tiles, each of which measure anywhere from 10–40 km across. The polygons are not flat – rather their centres rise up tens of metres above their edges to create a gently rolling icescape.

Physics World:
New Horizons lifts the lid on Pluto's peculiar polygons, Hamish Johnston

Reading, Writing, Magnetism...

Posted by Reginald L. Goodwin on June 1, 2016 at 5:16am

A depiction of magnetic charge ice. Nanoscale magnets are arranged in a two-dimensional lattice. Each nanomagnet produces a pair of magnetic charges, one positive (red ball on the north pole) and one negative (blue ball on the south pole). The magnetic flux lines (white) point from positive charges to negative charges. (Image credit: Yong-Lei Wang/Zhili Xiao)

Topics: Computer Science, Condensed Matter Physics, Electromagnetism, Materials Science, Nanotechnology, Solid State Physics

Note: Title is derived from the home page (third frame in CSS - cascading style sheet format) on ANL.gov.

A team of scientists working at the U.S. Department of Energy's (DOE's) Argonne National Laboratory has created a new material, called "rewritable magnetic charge ice," that permits an unprecedented degree of control over local magnetic fields and could pave the way for new computing technologies.

The scientists' research report on development of magnetic charge ice is published in the May 20 issue of the journal Science. "With potential applications involving data storage, memory and logic devices, magnetic charge ice could someday lead to smaller and more powerful computers or even play a role in quantum computing." said Zhili Xiao who holds a joint appointment between Argonne and Northern Illinois University.

Current magnetic storage and recording devices, such as computer hard disks, contain nanomagnets with two polarities, each of which is used to represent either 0 or 1 — the binary digits, or bits, used in computers. A magnetic charge ice system could have eight possible configurations instead of two, resulting in denser storage capabilities or added functionality unavailable in current technologies.

Argonne National Laboratories:
Scientists create 'magnetic charge ice', Jared Sagoff, Tom Parisi

Fifth Force...

Posted by Reginald L. Goodwin on May 31, 2016 at 5:15am

Credit: Avariel Falcon/Flickr, CC BY 2.0

Topics: Experimental Physics, Particle Physics, Radiation, Theoretical Physics

The Four (currently well-known) Forces: The Strong Force, the Electromagnetic Force, the Weak Force and Gravity. See: this link, which includes a brief primer on each and Feynman Diagrams on the strong and weak forces. Debate is going on now whether the new Force is evidence of Dark Energy, Dark Matter; a "Dark Photon" at 17 MeV, or what they refer to in the article as a "protophobic X (Greek letter Chi) boson." As with all reporting of scientific investigations, this is in its preliminary stages.

A laboratory experiment in Hungary has spotted an anomaly in radioactive decay that could be the signature of a previously unknown fifth fundamental force of nature, physicists say—if the finding holds up.

Attila Krasznahorkay at the Hungarian Academy of Sciences’s Institute for Nuclear Research in Debrecen, Hungary, and his colleagues reported their surprising result in 2015 on the arXiv preprint server, and this January in the journal Physical Review Letters. But the report – which posited the existence of a new, light boson only 34 times heavier than the electron—was largely overlooked.

Then, on April 25, a group of US theoretical physicists brought the finding to wider attention by publishing its own analysis of the result on arXiv. The theorists showed that the data didn’t conflict with any previous experiments—and concluded that it could be evidence for a fifth fundamental force. “We brought it out from relative obscurity,” says Jonathan Feng, at the University of California, Irvine, the lead author of the arXiv report.

Four days later, two of Feng's colleagues discussed the finding at a workshop at the SLAC National Accelerator Laboratory in Menlo Park, California. Researchers there were sceptical but excited about the idea, says Bogdan Wojtsekhowski, a physicist at the Thomas Jefferson National Accelerator Facility in Newport News, Virginia. “Many participants in the workshop are thinking about different ways to check it,” he says. Groups in Europe and the United States say that they should be able to confirm or rebut the Hungarian experimental results within about a year.

Scientific American:
Some theorists say a radioactive decay anomaly could imply a fundamental new force
Edwin Cartlidge

Two For The Price Of One...

Posted by Reginald L. Goodwin on May 30, 2016 at 12:18pm

Researchers have created a two-mode "Schrödinger's cat state" for the first time. (Courtesy: Michael S Helfenbein/Yale University)

Topics: Experimental Physics, Modern Physics, Quantum Computer, Quantum Mechanics, Schrödinger’s cat (s)

Schrödinger's cat now has a second box to play in, thanks to an international team of physicists that has created a two-mode "Schrödinger's cat state" for the first time. The experiment brings together two purely quantum properties, in that the "cat" (i.e. the photons) is simultaneously "alive and dead" (in a superposition of states) while also in two locations at once (the two boxes are entangled with one another).

The experiment is a step towards creating the larger and more sophisticated quantum states that are necessary to make quantum computing a reality. The team says that the work also demonstrates a two-logical-qubit system with in-built quantum error correction, making it a great resource for quantum metrology and quantum-communication networks.

Physics World: Schrödinger's cat lives and dies in two boxes at once
Tushna Commissariat

Black Holes and Dark Matter...

Posted by Reginald L. Goodwin on May 27, 2016 at 5:55am

After masking out all known stars, galaxies and artifacts and enhancing what's left, an irregular background glow appears. This is the cosmic infrared background (CIB); lighter colors indicate brighter areas. The CIB glow is more irregular than can be explained by distant unresolved galaxies, and this excess structure is thought to be light emitted when the universe was less than a billion years old. Scientists say it likely originated from the first luminous objects to form in the universe, which includes both the first stars and black holes.
Credits: NASA/JPL-Caltech/A. Kashlinsky (Goddard)

Topics: Astrophysics, Black Holes, Dark Matter, Physics Humor

I'll admit to being a fan of The Flash, but an informed one. For instance, speed in physics - along with mass (that's "us") is associated with momentum; acceleration and mass is associated with force. Every time I hear "speed force," I cringe. There was the memorable episode where Barry "talked" to the speed force (who looked like Joe, Iris, his mom and dad; a wraith that looked like him), which the writers obligatorily associated with Dark Energy, Dark Matter and the Big Bang. Barry had one memorable line that sounded kinda "science-y" when conversing with said speed deities: "this is like talking to gravity, or light," which as a part of nature, are not typically conversant. This of course is the fanciful departure of Hollywood cartoon physics, and as I allude at the link provided: don't take me to your Sci-Fi movie night!

The following is rather exciting, a hypothesis that will have to stand up to relentless peer review. Even though I'm a fan of superhero comic shows, I look forward to the coming published scientific conversations that will eventually (hopefully) hash this out.

Dark matter is a mysterious substance composing most of the material universe, now widely thought to be some form of massive exotic particle. An intriguing alternative view is that dark matter is made of black holes formed during the first second of our universe's existence, known as primordial black holes. Now a scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, suggests that this interpretation aligns with our knowledge of cosmic infrared and X-ray background glows and may explain the unexpectedly high masses of merging black holes detected last year.

"This study is an effort to bring together a broad set of ideas and observations to test how well they fit, and the fit is surprisingly good," said Alexander Kashlinsky, an astrophysicist at NASA Goddard. "If this is correct, then all galaxies, including our own, are embedded within a vast sphere of black holes each about 30 times the sun's mass."

In 2005, Kashlinsky led a team of astronomers using NASA's Spitzer Space Telescope to explore the background glow of infrared light in one part of the sky. The researchers reported excessive patchiness in the glow and concluded it was likely caused by the aggregate light of the first sources to illuminate the universe more than 13 billion years ago. Follow-up studies confirmed that this cosmic infrared background (CIB) showed similar unexpected structure in other parts of the sky.

NASA Scientist Suggests Possible Link Between Primordial Black Holes and Dark Matter
Francis Reddy

Finitistic, Infinitistic...

Posted by Reginald L. Goodwin on May 26, 2016 at 5:37am

Image Credit: Wylie Beckert for Quanta Magazine

Topics: Computer Science, Logic, Mathematical Models, Mathematical Physics

With a surprising new proof, two young mathematicians have found a bridge across the finite-infinite divide, helping at the same time to map this strange boundary.

The boundary does not pass between some huge finite number and the next, infinitely large one. Rather, it separates two kinds of mathematical statements: “finitistic” ones, which can be proved without invoking the concept of infinity, and “infinitistic” ones, which rest on the assumption — not evident in nature — that infinite objects exist.

Mapping and understanding this division is “at the heart of mathematical logic,” said Theodore Slaman, a professor of mathematics at the University of California, Berkeley. This endeavor leads directly to questions of mathematical objectivity, the meaning of infinity and the relationship between mathematics and physical reality.

Quanta Magazine: Mathematicians Bridge Finite-Infinite Divide, Natalie Wolchover

Directed Evolution...

Posted by Reginald L. Goodwin on May 25, 2016 at 5:56am

Topics: Biology, Diversity, Diversity in Science, Engineering, Research, Women in Science

US engineer Frances Arnold has won the Millennium Technology Prize for pioneering "directed evolution".

By driving a sped-up version of natural selection in the lab, the method has created new enzymes for industrial catalysts, household detergents, and even to make rocket fuel from sugar.

The €1m (£0.8m) prize is awarded biennially and Prof Arnold is the first female winner in its 12-year history.

It recognises developments that "change people's lives for the better".

The Technology Academy Finland, which presents the prize, said the deliberations began in November 2015 but that "there was only one outstanding candidate".

Prof Arnold, from the California Institute of Technology (Caltech), spoke to the BBC before travelling to Helsinki for Tuesday's ceremony.

She said the "basic concept" of using evolution to create better enzymes emerged from her laboratory more than 20 years ago.

BBC News: Evolutionary engineer wins tech prize, Jonathan Webb

Perching Robots...

Posted by Reginald L. Goodwin on May 24, 2016 at 5:24am

D.W.A.R.F.s: Drones Wirelessly Automated to Retrieve Forensics, Marvel Agents of Shield Wiki

Topics: Electrical Engineering, Mechanical Engineering, Robotics

Researchers have designed a small, flying robot that can perch on a wide range of surfaces before taking flight once more. The development is highlighted in the 20 May issue of Science. Aerial robots can serve many valuable purposes, such as surveying a site after a natural disaster or detecting hazardous chemicals — but the act of flight is energy-intensive. For animals that fly, such as birds and insects, a key way to conserve energy is to find a place to perch. "Unfortunately, today's flying microrobots run out of energy quickly," explained Moritz Alexander Graule of the Massachusetts Institute of Technology. "We want to keep them aloft longer without draining too much energy. For our robot, the perching method we developed requires about 1,000 times less energy than flying, thus prolonging the potential mission time."

AAAS: Bio-inspired Robot Perches, Resumes Flight, Michelle Hampson

Physics Identities...

Posted by Reginald L. Goodwin on May 23, 2016 at 4:46am

Image Source: Physics Today home page

Topics: Commentary, Diversity, Diversity in Science, Mark G. Raizen, Women in Science

This was an article that gave me a slight chuckle (the obvious double entendre of superhero secret identities and by inference of the topic trigonometric identities we all used to have to memorize). I can personally attest there are four major epochs (my reference) one goes through in the field:

"I major in physics";

"I 'majored' in physics";

"I work in a 'physics-related' field" also "my physics background helps me in my current field";

"I am a physicist."

Mark G. Raizen, one of the smartest physicist I know doing cutting edge research in atomic physics and quantum optics, was once a theoretical physics grad student under Steven Weinberg before he changed focus to being an experimental physicist. (Trivia: he even has a Wiki page on WOW.com). Mark once wished me a happy birthday on Facebook, referring to me as a "fellow physicist." I was at the time pursuing my Graduate Certificate in Microelectronics and Photonics from Stevens University I've since completed. I start again with the graduate physics department in the fall, as I only have 18 hours to a full Masters degree. With this background and my current industry focus on Implant, I hope to go as far as my preparation takes me.

I admit, I was flattered and honored, thinking my diversions - the military, industry, selling home security systems (long story) and high school physics teacher wasn't a "pure" path, and thus I bounced quite liberally between #2 and #3. Though he said it quite casually, it did knock me for a loop and change my own self-perceptions. Mark and Alicia Raizen's friendship has been inspirational (I met Alicia on an appointment with the aforementioned security company; then Mark who took me on a tour of his laboratory with his graduate students at UT Austin). I admit some evolution had to take place for me to get to and accept the fourth epoch. From that point and ever since, I have been referring to myself publicly, and proudly... as a physicist.

A series of interviews with undergraduates yields some surprising insights into how the students come to think of themselves as physicists.

Are you a physicist? How did you become a physicist? The answers to those questions are not as straightforward as one might think. The routes into physics are as diverse as physicists themselves. The sources of our early affinities for physics range from childhood fascinations with the universe to that introductory physics class that made you ask more questions than you could answer.

Acquiring a professional identity is a fundamental part of any student’s development.¹ Students are significantly more likely to persist with a program in physics—or any other discipline—when they identify themselves as students of that discipline.² However, developing an identity as a professional physicist and member of the physics community is a complicated process that can take a long time and involve overcoming multiple barriers.

To examine how identities change over time, we studied the experiences of 20 undergraduate physics students (3 women and 17 men) at Kansas State University over six semesters beginning with their modern physics class. Seven of the students remained in the study until the end. We interviewed each student several times, focusing on their developing experiences with physics and their perceptions of what it means to be a physicist. Our methods are described in the box on page 48.

We tracked changes in their perceptions over time as they engaged in more physics practices, such as upper-division coursework and undergraduate research. Students’ experiences with different authentic physics practices changed their perceptions of what it means to be a physicist. We used those changing perceptions as a starting point to investigate the students’ evolving physics identities.

Physics Today: Developing Physics Identities, Paul W. Irving and Eleanor C. Sayre

More Terrifying Than Foreigners...

Posted by Reginald L. Goodwin on May 13, 2016 at 5:41am

Image Source: CarloAlberto.org

Topics: Calculus, Differential Equations, Diversity, Politics

I think someone created a meme on Facebook from this incident. A little poking around the Internet revealed this WaPo article:

On Thursday evening, a 40-year-old man — with dark, curly hair, olive skin and an exotic foreign accent — boarded a plane. It was a regional jet making a short, uneventful hop from Philadelphia to nearby Syracuse.

Or so dozens of unsuspecting passengers thought.

The curly-haired man tried to keep to himself, intently if inscrutably scribbling on a notepad he’d brought aboard. His seatmate, a blond-haired, 30-something woman sporting flip-flops and a red tote bag, looked him over. He was wearing navy Diesel jeans and a red Lacoste sweater – a look he would later describe as “simple elegance” – but something about him didn’t seem right to her.

She decided to try out some small talk.

Is Syracuse home? She asked.

No, he replied curtly.

He similarly deflected further questions. He appeared laser-focused — perhaps too laser-focused — on the task at hand, those strange scribblings.

Skipping further into the article:

And then the big reveal: The woman wasn’t really sick at all! Instead this quick-thinking traveler had Seen Something, and so she had Said Something.

That Something she’d seen had been her seatmate’s cryptic notes, scrawled in a script she didn’t recognize. Maybe it was code, or some foreign lettering, possibly the details of a plot to destroy the dozens of innocent lives aboard American Airlines Flight 3950. She may have felt it her duty to alert the authorities just to be safe. The curly-haired man was, the agent informed him politely, suspected of terrorism.

The curly-haired man laughed.

He laughed because those scribbles weren’t Arabic, or another foreign language, or even some special secret terrorist code. They were math.

Yes, math. A differential equation, to be exact.

Had the crew or security members perhaps quickly googled this good-natured, bespectacled passenger before waylaying everyone for several hours, they might have learned that he — Guido Menzio — is a young but decorated Ivy League economist. And that he’s best known for his relatively technical work on search theory, which helped earn him a tenured associate professorship at the University of Pennsylvania as well as stints at Princeton and Stanford’s Hoover Institution.

Guido Menzio is a recipient of the prestigious Carlo Alberto medal, given to the best Italian economist under 40.

Did I mention he's Italian (not Arab/Near Eastern)? There are myriad other ethnic groups with "swarthy" complexions on the planet. Besides, here in the US, the threat of terrorism statistically may be of the homegrown and non-swarthy variety.

Majoring in a STEM field yields more than its own stereotypes: dorky, nerdy, socially awkward (I'm talking to you, "Big Bang Theory"), unattractive, but TERRORIST? I admit, the course we all affectionately called "DIFFY Qs" was daunting, but it didn't rewire any of us for violence. Have we gotten this addled in the brain?

So, in the era of not wanting actual experts in government or well, ANYTHING; in the era of racism, xenophobia, bombast, blatant lying, homophobia and misogyny as crass, carnival-barking political tactics (applicable when you've subordinated the processes a republic uses selecting its leaders into "reality TV," from a public caricature having more in common with "A Pimp Named Slickback") appealing to our lesser angels, we are SHOCKED that mathematics has literally become "Thoughtcrime"? Instead of a "shining city on a hill," we've become a dung heap infested with maggots in a junkyard - a joke! "Idiocracy" as a comedy was placed 500 years hence. That Apocalypse is now. All the hand-wringing about this being a strange election cycle is now solved. After telling Gorbachev to "tear down that wall," we're apparently intent on building another more lasting monument in the thick mortar paste of breathtaking stupidity. Sadly, the minions of this effort are PROUD of who and what they DON'T know. For them, ignorance is not just bliss: it's a belief system. And, you cannot explain science, mathematics, history, the economy or climate change... to a cult.

Rising xenophobia stoked by the presidential campaign, he (Guido) suggested, may soon make things worse for people who happen to look a little other-ish.

Washington Post:
Ivy League economist ethnically profiled, interrogated for doing math on American Airlines flight
Catherine Rampell

Blog break for ten days. Back on 23 May.

ExoMars...

Posted by Reginald L. Goodwin on May 12, 2016 at 5:09am

ExoMars 2016 liftoff - ESA

Topics: Astronomy, Astrophysics, ESA, Mars, Planetary Science

This was obviously in March, but we're five months from the actual encounter with the red planet. I'll keep up with any updates and note progress and hopefully, a successful planetary landing.

The first of two joint European Space Agency (ESA)-Roscosmos missions to Mars has begun a seven-month journey to the Red Planet, where it will address unsolved mysteries of the planet’s atmosphere that could indicate present-day geological — or even biological — activity.

The Trace Gas Orbiter and the Schiaparelli entry, descent, and landing demonstrator lifted off on a Proton-M rocket operated by Russia’s Roscosmos at 05:31 a.m. EDT (09:31 GMT) March 14 from Baikonur, Kazakhstan.

The payload fairing was released following separation of Proton’s first and second stages. The third stage separated nearly 10 minutes after liftoff.

The Breeze-M upper stage, with ExoMars attached, then completed a series of four burns before the spacecraft was released at 4:13 p.m. EDT (20:13 GMT).

Signals from the spacecraft, received at ESA’s control center in Darmstadt, Germany via the Malindi ground tracking station in Africa at 5:29 p.m. EDT (21:29 GMT), confirmed that the launch was fully successful and the spacecraft is in good health.

The orbiter’s solar wings have also now unfolded and the craft is on its way to Mars.

Astronomy: ExoMars sets off to solve the Red Planet’s mysteries

Nano Thermometer...

Posted by Reginald L. Goodwin on May 11, 2016 at 5:15am

Alexis Vallée-Bélisle and his research team have developed DNA-based thermometers that allow the measurement of temperature at the nanoscale. Design: Kotkoa.

Topics: Biology, DNA, Nanotechnology

Researchers have known for more than 60 years now that DNA molecules unfold when heated and refold when cooleddown again. More recently they also discovered that living organisms employ biomolecules such as proteins or RNA (a molecule similar to DNA) as nanothermometers thanks to this unfolding and folding. “Inspired by these natural nanothermometers, we have now created various DNA structures that can fold and unfold at specifically defined temperatures,” explains team leader Alexis Vallée-Bélisle.

The team used the simple Watson–Crick base pair code of DNA and the so-called Hoogsteen interactions to create their DNA structures. The good thing about DNA is that its chemistry is relatively simple and programmable, says team member David Garreau. “DNA is made from four different nucleotide molecules, A, C, G and T. Nucleotide A binds weakly to nucleotide T, whereas nucleotide C binds strongly to nucleotide G. Using these simple rules, we were able to create DNA structures that can be programmed to fold and unfold at specific temperatures.”

Nanotech Web: DNA makes tiny thermometer, Belle Dumé

Gedanken...

Posted by Reginald L. Goodwin on May 10, 2016 at 5:37am

Image Source: Pics About Space

Topics: Einstein, FTL, General Relativity, Star Trek

For the record: \\//_. Now that my "Trek creds" have been established...

Gedanken is a German word for "thought." It is often colloquially defined along with the word experiment, which is where a lot of the notions of Special and General Relativity took place in Einstein's mind; his innate ability to conceptualize a tough idea.

It is also by definition, an experiment that is impractical to carry out. Part of it being impractical is the incredible energies that would be needed to propel a star ship to even 0.10 c, or in Trek parlance: "impulse." An aircraft carrier is ~64,000 metric tons (I'm using it as my "Enterprise," which is supposed to be pretty big). That's 64,000,000 kilograms. Simply multiply it by 0.10 x 3.0 x 10⁸ m/s² this will give you the energy output in Joules: 1.92 x 10¹⁵. The PLANET in 2013 generated 5.67 x 10²⁰ Joules.

Part of the constant research is that sometimes what you're looking for may not be found, but the techniques you use in any analysis may have an application in areas you may not have imagined. As such, it becomes a part of the research one can reference and build on, thereby increasing the overall knowledge of a subject area.

Abstract

Warp drives are very interesting configurations in general relativity: At least theoretically, they provide a way to travel at superluminal speeds, albeit at the cost of requiring exotic matter to exist as solutions of Einstein’s equations. However, even if one succeeded in providing the necessary exotic matter to build them, it would still be necessary to check whether they would survive to the switching on of quantum effects. Semiclassical corrections to warp-drive geometries have been analyzed only for eternal warp-drive bubbles traveling at fixed superluminal speeds. Here, we investigate the more realistic case in which a superluminal warp drive is created out of an initially flat spacetime. First of all we analyze the causal structure of eternal and dynamical warp-drive spacetimes. Then we pass to the analysis of the renormalized stress-energy tensor (RSET) of a quantum field in these geometries. While the behavior of the RSET in these geometries has close similarities to that in the geometries associated with gravitational collapse, it shows dramatic differences too. On one side, an observer located at the center of a superluminal warp-drive bubble would generically experience a thermal flux of Hawking particles. On the other side, such Hawking flux will be generically extremely high if the exotic matter supporting the warp drive has its origin in a quantum field satisfying some form of quantum inequalities. Most of all, we find that the RSET will exponentially grow in time close to, and on, the front wall of the superluminal bubble. Consequently, one is led to conclude that the warp-drive geometries are unstable against semiclassical backreaction.

Physics arXiv: Semiclassical instability of dynamical warp drives
Stefano Finazzi,^1,∗ Stefano Liberati,¹,^† and Carlos Barcelo²

Changeling...

Posted by Reginald L. Goodwin on May 9, 2016 at 5:42am

Image courtesy of Ilsa van Meerbeek
The material is capable o both withstanding heavy loads or deforming under them as needed.

Topics: Materials Science, Metamaterials, Robotics

For all the discussion surrounding artificial intelligence and robots recently, the stiff, dull metal exterior of robots has only recently begun to evolve. While human-like robots, with silicon skin, can simulate emotions but robots with the shape-shifting ability of the Transformers have yet to hit the market. However, Prof. Robert Shepherd, mechanical and aerospace engineering, is developing a material that could soon bring that to reality.

Shepherd and his team at Organic Robotics Lab is working on a metal-rubber composite by harnessing the strength of a metallic alloy and the flexibility of a soft silicone foam. The material can withstanding heavy loads or deform under them upon command. The only requirement for switching between these properties is a change in temperature.

Cornell Daily Sun:
Cornell Researchers Create New Material Capable of Shifting States, Arnav Ghosh