Reginald L. Goodwin's Posts (3016)

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Six-Legged Lizards...


Researchers can learn a lot from a lizard scampering across the hot desert sand or an insect crawling atop a pile of plant litter. Chen Li and colleagues from the Georgia Institute of Technology in Atlanta took cues from such creatures and designed a robot that uses six legs to traverse a bed of dry, loose grains.



The robotic design isn't as effective as a lizard's but it can move through sand at a reasonable pace without getting stuck, and it may help to boost the performance of roving and walking robots, such as the Mars rovers, the researchers said. They noted that previous studies of objects moving through air and water have led to improvements of industrial products such as aircraft wings and underwater robots.



"There's only going to be an increasing number of robots running around our planet and others," said Daniel Goldman, a co-author of the report that appears in the 22 March issue of Science. "We'd like to identify principles that allow devices to move effectively under diverse conditions."

Science: New, Off-Road Robot Inspired by Nature

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Cuprates...

Philip Phillips, a professor of physics and of chemistry at Illinois, and colleagues found that something other than electrons carries the current in copper-containing superconductors known as cuprates.

CHAMPAIGN, Ill. — To engineers, it’s a tale as old as time: Electrical current is carried through materials by flowing electrons. But physicists at the University of Illinois and the University of Pennsylvania found that for copper-containing superconductors, known as cuprates, electrons are not enough to carry the current.



“The story of electrical conduction in metals is told entirely in terms of electrons. The cuprates show that there is something completely new to be understood beyond what electrons are doing,” said Philip Phillips, a professor of physics and of chemistry at the U. of I.



In physics, Luttinger’s theorem states that the number of electrons in a material is the same as the number of electrons in all of its atoms added together. Electrons are the sub-atomic particles that carry the current in a conductive material. Much-studied conducting materials, such as metals and semiconductors, hold true to the theorem.



Phillips’ group works on the theory behind high-temperature superconductors. In superconductors, current flows freely without resistance. Cuprate superconductors have puzzled physicists with their superconducting ability since their discovery in 1987.



The researchers developed a model outlining the breakdown of Luttinger’s theorem that is applicable to cuprate superconductors, since the hypotheses that the theorem is built on are violated at certain energies in these materials. The group tested it and indeed found discrepancies between the measured charge and the number of mobile electrons in cuprate superconductors, defying Luttinger.

News Bureau, Illinois:
Electrons are not enough: Cuprate superconductors defy convention

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Planck's Four Surprises...


Lopsided universe: Planck’s new skymap shows that one half of the microwave background is brighter than the other, and the universe has a large cold spot. Credit: ESA and the Planck Collaboration

By now you've probably heard about the amazing new cosmic snapshot from the European Space Agency’s Planck spacecraft. It is one of those scientific achievements so mind-boggling that you have to spend a bit of time with it to truly appreciate what you are seeing. This is relic radiation from when the universe was 370,000 years old, still all aglow from the Big Bang. The radiation has been traveling 13.8 billion years since then, across ever-expanding stretches of space, before landing in Planck’s detectors. Then it took a tremendous feat of imagination and insight to translate that noisy signal into a comprehensible map of what the universe looked like in its infancy.



So let’s step back for a moment, look at how this image came to be, and consider some of the more surprising details hidden within it. [Headers lead into the topics]



The map started out as static.

Human brains cannot make sense of all the data from Planck.

The universe is darker, lighter, slower, and older than we thought.

The universe is lopsided.

Discovery: Four Surprises in Planck's New Map of the Cosmos

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Chicxulub Snowball...

...the prevailing theory:

 


Current theory:

 

The rocky object that wiped out the dinosaurs 65 million years ago may have been a comet, rather than an asteroid, scientists say.

 

The 112-mile (180 kilometers) Chicxulub crater in Mexico was made by the impact that caused the extinction of dinosaurs and about 70 percent of all species on Earth, many scientists believe. A new study suggests the crater was probably blasted out by a faster, smaller object than previously thought, according to research presented this week at the 44th Lunar and Planetary Science Conference in The Woodlands, Texas.

 

Evidence of the space rock's impact comes from a worldwide layer of sediments containing high levels of the element iridium, dubbed the Cretaceous-Paleogene (K-Pg) boundary, which could not have occurred on Earth naturally.

 

The new research suggests the often-cited iridium values are incorrect, however. The scientists compared these values with levels of osmium, another element delivered by the impact.

 

Their calculations suggested the space rock generated less debris than previously thought, implying the space rock was a smaller object. In order for the smaller rock to have created the giant Chicxulub crater, it had to have been going exceedingly fast, the researchers concluded.

 

Huffington Science: New Study Suggests Comet Instead Caused Extinction Event

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Einstein, Entropy and Information...


...as explained by one of the smartest physicists I know!

James Clerk Maxwell formulated the equations that describe electricity and magnetism. He was Einstein's hero! Both are the reason why we're in the age of laptops and I-phones.

Physics Colloquium, University of Texas Physics Department. Mark has a process that's a little more efficient than Steven Chu's (yes, THAT Steven Chu). It's worth your time to watch this presentation, and seek out colloquium wherever you are. Science is open and a social endeavor.

Something I used to enjoy in Texas, that I admittedly miss...
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Surely Not Joking...

Electrons traveling through two slits and a single slit

Physicists in the US and Canada say that they have done the best job yet of realizing Richard Feynman's famous thought experiment about how single electrons pass through two slits. Although the researchers are not the first to recreate the experiment in the lab, they say that their incarnation best captures the essence of the original exercise.

 

Feynman originally outlined his thought experiment in volume three of his famous series The Feynman Lectures on Physics as a way of illustrating wave–particle duality in quantum mechanics. In the book, he invites the reader to imagine firing individual electrons through two slits and then marking the position where each electron strikes a screen behind the slits.

 

After many electrons have passed through the slits, the marks on the screen will comprise a diffraction pattern – illustrating the wave-like behaviour of each electron. But if one were to cover up one of the slits so that each electron could only pass through the other slit, the diffraction pattern would not appear – showing that each electron does indeed travel through both slits.

 

Physics World: Feynman's double-slit experiment gets a makeover
Feynman Physics Lectures: Site Link and You Tube Channel

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And Statistics...


"Figures often beguile me, particularly when I have the arranging of them myself; in which case the remark attributed to [19th-century British Prime Minister Benjamin] Disraeli would often apply with justice and force: 'There are three kinds of lies: lies, damned lies, and statistics.'"


Samuel Clemmons/Mark Twain, "Chapters from My Autobiography"

...Our analysis finds that the QGRE correlates with only one metric, the graduate GPA (but it is such a weak correlation the scientist in me rebels when fitting it to a line). That said, we find undergraduate GPA to be a better predictor of graduate GPA. We also find that undergraduate GPA is correlated with all three sections of the General GRE.

 

So why use the GRE at all? One certain answer: national rankings. Consider US News, whose rankings of graduate programs are widely influential among both prospective graduate students and administrators....

 

Justifying using the GRE becomes significantly more complicated, however, when the test results are dissected by race and gender. The figure plots QGRE scores by race/ethnicity and gender for US citizens whose intended graduate major was "physical sciences". The top and bottom of the lines are the 75th and 25th percentiles of the score distributions, respectively; the tick is the mean. This pattern is qualitatively unchanged when controlling for undergraduate GPA. Note the implications for diversity of using 700 as a minimum acceptable score: nearly three quarters of Hispanics would be rejected, and significantly more than this for American Indians, African Americans, and Puerto Ricans; similarly, women are filtered out at a higher rate than men. Mixing cut-off scores with these racial and gender disparities sets the foundation of a glass ceiling erected by the lopsided treatment of minorities and women before they even set foot in grad school.

 

The Asian > White > Hispanic > Black pattern permeates standardized testing: it is the same for the SAT, and is reflected in the recent race-based levels set by Florida and Virginia for grade schoolers' performance on state-wide standardized tests.

 

To be fair: there's more data and insight at the link below. The statistics (I feel), is a measure of where we've allowed ourselves as a society to get "comfortable." I have mused on this at length in the posts: "A Matter of Marketing" and "Dark Matters." Einstein is the source of the following quotes:

 

1. "It seems to be a universal fact that minorities--especially when the individuals composing them can be recognized by physical characteristics--are treated by the majorities among whom they live as an inferior order of beings. The tragedy of such a fate lies not merely in the unfair treatment to which these minorities are automatically subjected in social and economic matters, but also in the fact that under the suggestive influence of the majority most of the victims themselves succumb to the same prejudice and regard their kind as inferior beings. This second and greater part of the evil can be overcome by closer association and by the deliberate education of the minority, whose spiritual liberation can thus be accomplished.

"The resolute efforts of the American Negro in this direction deserve approval and assistance."

Mein Weltbild, Amsterdam: Querido Verilog, 1934, pp 117-118.

 

2. "Insanity: doing the same thing over and over again and expecting different results."

 

Bear with me...

 

APS Back Page: Admissions Criteria and Diversity in Graduate School, Casey W. Miller

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Phaser Effect...



The theoretical foundations for the laser were established in 1917, when Einstein formulated the quantum theory of radiation, describing the absorption, spontaneous emission, and stimulated emission of electromagnetic radiation. Its realization stayed hidden for decades, however, before it emerged in the form of masers and lasers, which emit microwave and visible radiation, respectively. The range of emitted frequencies was soon broadened to cover wavelengths from the infrared to the x-ray range, and lasing was extrapolated beyond the realm of optics. Free-electron lasers, in which the active medium is a relativistic electron beam, helped cover extreme wavelength ranges and are now the basis for a new generation of experimental facilities for x-ray experiments. Atom lasers—emitting matter waves instead of photons—have also been demonstrated. Recently, the laser idea was extended to sound waves, leading to the conceptualization of the acoustic analog of a laser, which emits phonons (lattice vibrations) instead of photons. Now, writing in Physical Review Letters, Imran Mahboob at the NTT Basic Research Laboratories, Japan, and colleagues report on the experimental demonstration of a purely mechanical counterpart of a three-level laser scheme [1]. The device, excited by acoustic vibrations, amplifies sound waves through stimulated emission of phonons and acts as a phonon laser: a spectrally pure source of phonons with a frequency of around 1.7 megahertz (MHz).



What is the appeal of phonon lasers? One potential advantage is that their emission has smaller wavelength than that of photon lasers at the same frequency because the sound speed is much smaller than the speed of light. This could help improve the resolution of tomographic, ultrasound, and other imaging techniques. In analogy with their optical cousins, phonon lasers might deliver directional and coherent acoustic beams, which could be coupled to nanoscale mechanical engines or used in communication networks based on acoustic waves. But as the history of optical lasers suggests, most applications of future phonon lasers may be completely unexpected.

The Trekkie in me notes: from the phonon pump, the upper-to-intermediate level transition is called "Phaser Emission." Wonder if there's a stun setting?

American Physical Society: Lasers of Pure Sound

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Kawazulite...

Kawazulite is a natural “topological insulator"

In a step toward understanding and exploiting an exotic form of matter that has been sparking excitement for potential applications in a new genre of supercomputers, scientists are reporting the first identification of a naturally occurring “topological insulator” (TI). Their report on discovery of the material, retrieved from an abandoned gold mine in the Czech Republic, appears in the ACS journal Nano Letters.

 

Pascal Gehring and colleagues point out that synthetic TIs, discovered only a decade ago, are regarded as a new horizon in materials science. Unlike conventional electrical insulators, which do not conduct electricity, TIs have the unique property of conducting electricity on their surface, while acting as an insulator inside. Although seemingly simple, this type of surface could allow manipulation of the spin of an electron, paving the way for development of a quantum computer. Such a computer would crunch data much faster than today’s best supercomputers.

 

American Chemical Society: First discovery of a natural topological insulator

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The Physics of Maple Syrup...

..."just when you thought it was safe to go into the IHOP"...Smiley

2D cross section through a fiber-vessel pair showing the water, ice and gas regions, the moving interfaces as well as the 1D region corresponding to simplified model geometry. Figure credit: Maurizio Ceseri and John Stockie

Philadelphia, PA—For many of us, maple syrup is an essential part of breakfast—a staple accompaniment to pancakes and waffles—but rarely do we think about the complicated and little-understood physiological aspects of syrup production. Each spring, maple growers in temperate regions around the world collect sap from sugar maple trees, which is one of the first steps in producing this delicious condiment.

 

However, the mechanisms behind sap exudation—processes that trigger pressure differences causing sap to flow— in maple trees are a topic of much debate. In a paper published today in the SIAM Journal on Applied Mathematics, authors Maurizio Ceseri and John Stockie shed light on this subject by proposing a mathematical model for the essential physiological processes that drive sap flow.

 

Sugars are produced in the leaves of the maple tree by photosynthesis with the help of absorbed water, carbon dioxide, and sunlight, and are consumed for current growth, or stored as starch. In the cold, dormant season, some of the starch enters the sap, where it remains mostly frozen until the spring. In the period between this dormant state and the active growing season (during cold nights with below-freezing temperatures followed by mild, warm days with above-freezing conditions), the stored starch is converted into sugar and the sap pressure grows, allowing it to exude naturally from the tap hole when tapped.

Society for Industrial and Applied Mathematics: Pancakes with a side of math

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Do Good...

John Green, meme from Facebook

Warnie C. Hay, D.D. was my pastor in Winston-Salem, NC.

He was  a huge mountain of a man. No matter how tall I got, he never seemed small (or short to me). I heard prior to his then current life, he'd been a truck driver and could "drink a fifth of liquor straight." [My father was the source of that quote.]

He, like a lot of leaders that actually shepherded their flocks, was keenly interested in my education, since as recently as the 60s, he and a lot of other pastors in the vein of Dr. King fought for our access to it, and our equal treatment regarding it.

"How are you doing in school, son?" We were all either "son" or "daughter" to him.

"Well...I'm studying evolution in biology with Mrs. Brake."

"OK, son. Do good!"

[...] That was it. I told him my grade on the exam later: B+. He smiled.

 

He was also pleased at my interest in amateur astronomy. He didn't lecture me when a mishap chemistry experiment resulted in a spectacular explosion in my room (don't worry: my parents did!). The only reservation he communicated was after the Challenger Disaster (I was in the Air Force, home on a visit): he preferred I not become an astronaut, though I never promised him I wouldn't.


I miss that simple encouragement, and the divorce from what is now political implications and spiritual litmus tests that have frozen critical thinking into ice age glaciers. There was no falsified "debate" on evolution vs. creationism; 6,000 years estimates from the Gregorian calendar vs. 14.6 billion years as estimated by measured light reaching us from the farthest stars. Science unimpeded by such machinations brings benefits to society like finding cures for diseases and advancing technologies that supply water, food, clean air, but I'd be the first to say an astronomer et al could not lead a "March on Washington." Different skill sets are required for such an endeavor.

 

Dr. Hay had contacts with congressional leaders. He could have gotten me an appointment at one of the service academies. I declined, and stated I wanted to go to college close to home. He respected my wishes, and I did that. He invited me to bring some of my classmates and discuss majoring in engineering and science at his "Super Saturday" career day, which he did every year...at church. Yet, I don't ever recall his ever needing to 'correct my thinking,' challenge what I'd learned...or that he seemed threatened at all by my interest in science as some seem to be today. Galileo and Copernicus would have appreciated him, and our youth less confused by this boondoggle.

Note this excerpt:


"Science has been responsible for roughly half of all US economic growth since World War II, and it lies at the core of most major unsolved policy challenges.

 

"In an age when most major public policy challenges revolve around science, less than 2 percent of congresspersons have professional backgrounds in it. The membership of the 112th Congress, which ran from January 2011 to January 2013, included one physicist, one chemist, six engineers, and one microbiologist.

 

"In contrast, how many representatives and senators do you suppose have law degrees - and whom many suspect avoided college science classes like the plague? Two hundred twenty-two. It's little wonder we have more rhetoric than fact in our national policy making..."


Shawn Lawrence Otto, Fool Me Twice: Fighting the Assault of Science in America, Rodale Books, October, 2011.

He passed two months before my own father in the same year, 1999. It was a pretty sad summer for me, to say the least. Neither man quite made it to the next century, born and expired in the 20th. They are buried, as now is my mother (2009), in Piedmont Memorial Gardens. These were people who worked hard, got passed over unfairly for promotions, experienced their own "sequester" in the form of where we all could live: care of Jim Crow. Knowledge was precious and appreciated, as my father used to say to me (numerous times): "once you get it in your head, no one can take that from you." My mother would tell me: "you can do anything you want to, once you put your mind to it, and trust God: you can do it!" I miss my cheering Valkyrie.

I miss this generation, and their encouragement to improve and advance, appreciative of the sacrifices of past giants, without guile, obfuscations, machinations or agenda, encouraged to simply:

"Do good."
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Higgs Confirmed!...



A newfound particle discovered at the world's largest atom smasher last year is, indeed, the Higgs boson, the particle thought to give other matter its mass, scientists reported today (March 14) at the annual Rencontres de Moriond conference in Italy.

 

Physicists announced on July 4, 2012, that, with more than 99 percent certainty, they had found a new elementary particle weighing about 126 times the mass of the proton that was likely the long-sought Higgs boson. The Higgs is sometimes referred to as the "God particle," to the chagrin of many scientists, who prefer its official name.

 

But the two experiments, CMS and ATLAS, hadn't collected enough data to say the particle was, for sure, the Higgs boson, the last undiscovered piece of the puzzle predicted by the Standard Model, the reigning theory of particle physics.

 

Now, after collecting two and a half times more data inside the Large Hadron Collider (LHC) — where protons zip at near light-speed around the 17-mile-long (27 kilometer) underground ring beneath Switzerland and France — physicists say the particle is the Higgs. [In Photos: Searching for the Higgs Boson]

 

"The preliminary results with the full 2012 data set are magnificent and to me it is clear that we are dealing with a Higgs boson though we still have a long way to go to know what kind of Higgs boson it is," said CMS spokesperson Joe Incandela in a statement.

 

Space.com: Confirmed! Newfound Particle Is the Higgs

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Fermi Bubbles, Dark Matter...



In 2011, an analysis of data from a NASA Fermi Gamma-Ray Space Telescope turned up massive, previously unseen galactic structures. A group of astrophysicists located two massive bubbles of plasma, now know as "Fermi Bubbles," each extending tens of thousands of light-years, emitting high-energy radiation above and below the plane of the galaxy. The structure spans more than half of the visible sky, from the constellation Virgo to the constellation Grus, and it may be millions of years old.

 

Now, more recently, in 2013, astrophysicists Dan Hooper of Fermi National Accelerator Laboratory and Tracy Slatyer at Princeton University, have published a study suggesting that a massive outflow of charged particles from Fermi bubbles, as they are known, outflows of charged particles (gamma rays) traveling at nearly a third the speed of light from the center of the Milky Way galaxy, may be partly due to collisions between dark matter particles that result in their annihilation, and the subsequent creation of the building blocks of visible matter—charged particles that appear as two lobes or "bubbles," above and below the center of the Milky Way Galaxy.

 

Another possibility includes a particle jet from the supermassive black hole at the galactic center.

 

Daily Galaxy: Colossal Bubbles at Milky Way's Plane --"May Be the Annihilation of Dark Matter"

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Inner Space...

The actin fibers of a nerve cell's growing axon are shown in red - NIH

The cells of our bodies aren't just featureless bags of proteins. Many of them have distinctive shapes and structures that are essential to their function. Neurons, for example, extend processes away from their cell bodies for up to several feet. The lining of your intestines has a specialized surface for absorbing food. And when immune cells encounter an infected cell, they form a specialized surface that allows them to kill the infected cell without harming its neighbors.

 

To form all of these structures, the cell has to be internally specialized, with different regions having distinct sets of proteins and chemicals. But it's hard to study the processes that make one part of the cell different from another. Most of the tools we have are rather blunt and affect the whole cell equally. But researchers have reported a clever trick that lets them activate proteins in a specific location: stick them on a tiny magnetic bead, then move the bead around inside the cell.

 

Ars Technica: “Magnetogenetics” probes the inner space of a cell

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Atomic Collapse...

An artificial atomic nucleus made up of five charged calcium dimmers is centered in an atomic-collapse electron cloud (Image courtesy of Michael Crommie) 



The first experimental observation of a quantum mechanical phenomenon that was predicted nearly 70 years ago holds important implications for the future of graphene-based electronic devices. Working with microscopic artificial atomic nuclei fabricated on graphene, a collaboration of researchers led by scientists with the U.S. Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) and the University of California (UC) Berkeley have imaged the “atomic collapse” states theorized to occur around super-large atomic nuclei.



Atomic collapse is one of the holy grails of graphene research, as well as a holy grail of atomic and nuclear physics,” says Michael Crommie, a physicist who holds joint appointments with Berkeley Lab’s Materials Sciences Division and UC Berkeley’s Physics Department. “While this work represents a very nice confirmation of basic relativistic quantum mechanics predictions made many decades ago, it is also highly relevant for future nanoscale devices where electrical charge is concentrated into very small areas.”



Crommie is the corresponding author of a paper describing this work in the journal Science. The paper is titled “Observing Atomic Collapse Resonances in Artificial Nuclei on Graphene.” Co-authors are Yang Wang, Dillon Wong, Andrey Shytov, Victor Brar, Sangkook Choi, Qiong Wu, Hsin-Zon Tsai, William Regan, Alex Zettl, Roland Kawakami, Steven Louie, and Leonid Levitov.



Originating from the ideas of quantum mechanics pioneer Paul Dirac, atomic collapse theory holds that when the positive electrical charge of a super-heavy atomic nucleus surpasses a critical threshold, the resulting strong Coulomb field causes a negatively charged electron to populate a state where the electron spirals down to the nucleus and then spirals away again, emitting a positron (a positively–charged electron) in the process. This highly unusual electronic state is a significant departure from what happens in a typical atom, where electrons occupy stable circular orbits around the nucleus.
 
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Martian Life!...

This set of images compares rocks seen by NASA's Opportunity rover and Curiosity rover at two different parts of Mars. On the left is " Wopmay" rock, in Endurance Crater, Meridiani Planum, as studied by the Opportunity rover. On the right are the rocks of the "Sheepbed" unit in Yellowknife Bay, in Gale Crater, as seen by Curiosity. Image credit: NASA/JPL-Caltech/Cornell/MSSS

PASADENA, Calif. -- An analysis of a rock sample collected by NASA's Curiosity rover shows ancient Mars could have supported living microbes.



Scientists identified sulfur, nitrogen, hydrogen, oxygen, phosphorus and carbon -- some of the key chemical ingredients for life -- in the powder Curiosity drilled out of a sedimentary rock near an ancient stream bed in Gale Crater on the Red Planet last month.



"A fundamental question for this mission is whether Mars could have supported a habitable environment," said Michael Meyer, lead scientist for NASA's Mars Exploration Program at the agency's headquarters in Washington. "From what we know now, the answer is yes."

NASA: NASA Rover Finds Conditions Once Suited for Ancient Life on Mars

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Happy Birthday, Gustav Kirchhoff...



Gustav Robert Kirchhoff (12 March 1824 – 17 October 1887) was a German physicist who contributed to the fundamental understanding of electrical circuits, spectroscopy, and the emission of black-body radiation by heated objects.



He coined the term "black body" radiation in 1862, and two sets of independent concepts in both circuit theory and thermal emission are named "Kirchhoff's laws" after him, as well as a law of thermochemistry.



Kirchhoff Current Law (KCL): At any node (junction) in an electrical circuit, the sum of currents flowing into that node is equal to the sum of currents flowing out of that node, or: The algebraic sum of currents in a network of conductors meeting at a point is zero.



Kirchhoff Voltage Law (KVL): The directed sum of the electrical potential differences (voltage) around any closed network is zero, or: More simply, the sum of the emfs in any closed loop is equivalent to the sum of the potential drops in that loop, or: The algebraic sum of the products of the resistances of the conductors and the currents in them in a closed loop is equal to the total emf available in that loop.

Wikipedia: Gustav Kirchhoff

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Methuselah Star...



A team of astronomers using NASA's Hubble Space Telescope has taken an important step closer to finding the birth certificate of a star that's been around for a very long time.

"We have found that this is the oldest known star with a well-determined age," said Howard Bond of Pennsylvania State University in University Park, Pa., and the Space Telescope Science Institute in Baltimore, Md.

The star could be as old as 14.5 billion years (plus or minus 0.8 billion years), which at first glance would make it older than the universe's calculated age of about 13.8 billion years, an obvious dilemma.

But earlier estimates from observations dating back to 2000 placed the star as old as 16 billion years. And this age range presented a potential dilemma for cosmologists. "Maybe the cosmology is wrong, stellar physics is wrong, or the star's distance is wrong," Bond said. "So we set out to refine the distance."

The new Hubble age estimates reduce the range of measurement uncertainty, so that the star's age overlaps with the universe's age — as independently determined by the rate of expansion of space, an analysis of the microwave background from the big bang, and measurements of radioactive decay.

This "Methuselah star," cataloged as HD 140283, has been known about for more than a century because of its fast motion across the sky. The high rate of motion is evidence that the star is simply a visitor to our stellar neighborhood. Its orbit carries it down through the plane of our galaxy from the ancient halo of stars that encircle the Milky Way, and will eventually slingshot back to the galactic halo.

Hubble Site: Hubble Finds Birth Certificate of Oldest Known Star

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Matter-Antimatter...

Figure 1: See link for descriptions

While quantum mechanics is by now a well-established theory, it nonetheless still fascinates both newcomers and experts alike with unusual phenomena. The paradox of Schrödinger’s cat and the subtleties of the two-slit interference are timeless classics. Another less-familiar quantum effect, the oscillations of neutral mesons (bound states of a quark and an antiquark), has also intrigued legions of physicists for nearly sixty years [1]. These mesons oscillate back and forth between particle and antiparticle states. The theoretical ideas underlying this behavior involve concepts that are woven deeply into the history of particle physics. In Physical Review Letters, the LHCb Collaboration has now reported [2] the first significant single-measurement observation of oscillations in the neutral D -meson system.

American Physical Society: Viewpoint: Observing Matter-Antimatter Oscillations

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Pan-STARRS...

This graphic shows the comet’s expected positions in the sky throughout March. Image credit: NASA

On March 9 and 10, Pan-STARRS will be at its brightest, because that’s when it’s closest to the sun. Visible to the naked eye (but looking even better through binoculars or a telescope) at a dark site, the comet will appear as a bright “smear” of light low in the west up to an hour after sunset. And next week’s crescent moon can help locate Pan-STARRS: On March 12, the comet will lie to the moon’s upper left, and on the next night it will be on the moon’s lower right. After two weeks, the comet will have faded enough to require optical instruments to see it.

 

Discovery D-brief: Where Can I See Comet Pan-STARRS?

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