Ravian Physicists Club

SPACE MYTH: "The Sun is a ball of fire" NOT TRUE

The Sun is actually glowing, not burning. This might seem like an insignificant distinction to the average person, but the heat generated by the sun is actually the result of a nuclear reaction, not a chemical one which is what burning is. While we’re at it…

The Earth's magnetic field, which protects us from radiation from space, is getting weaker. We don't yet know why this is, but new evidence confirms it is happening unevenly across the planet with some areas getting more protection.

Evidence of weakening of the magnetic field, and it's geographically inconsistent nature, has been tracked for decades, but the November 2013 launch of the European Space Agency's three satellite Swarm constellation has allowed unprecedented precision in measuring these changes.

The field is a result of the Earth's iron core acting as a giant magnet. However, the core is not stable, with the magnetic north and south poles wandering around at rates of around 15 km/year for most of last century, and recently accelerating. Over periods of millions of years the poles sometimes switch places, and there is some speculation that such a switch is coming soon.

The north magnetic pole is currently moving towards Siberia from its location in Canada.

The field averages a strength of around 40,000nT, so even the loss of 80nT over North America (see above) is small. However, this is in a period of just six months – should the trend continue for long enough the effects could eventually become serious. A weaker magnetic field would expose the planet to increased radiation, both from distant supernovae and from the solar events, although there is no evidence that the doomsday scenario of a planet temporarily without any magnetic field at all has ever occurred.

A polarity flip, or drastic weakening would not be lethal, as demonstrated by the fact that past changes have not been associated with mass extinctions, but could expose powerlines and communication systems to much greater danger. On the positive side, auroras should become more spectacular and widespread. Should such an event occur, most scientists anticipate the timescale will be of the order of millennia, rather than decades, making the Daily Mail's call to “forget global warming and start worrying about the Earth's magnetic field” typically stupid.

The changes are driven by a complex set of sources, from the core, mantle and crust of the Earth and influences in space. The largest influence is thought to be the convection currents in the molten iron of the core causing expansion at some points and contraction at others. Thee convection currents may sometimes lead to domains where the magnetic field runs in the opposite direction to the main field, canceling part of it out.

The results were presented at the Third Swarm Science Meeting, held in Copenhagen on Thursday. The Swarm Mission Manager Dr Rune Floberghagen said, "These initial results demonstrate the excellent performance of Swarm. With unprecedented resolution, the data also exhibit Swarm's capability to map fine-scale features of the magnetic field."

Mysterious Bright Object Spotted On Titan

Astronomers scouring through images taken by NASA’s Cassini spacecraft last year have discovered a fleeting bright spot in one of the seas of Saturn’s moon, Titan. The intriguing feature, which has been coined "Magic Island," had never seen observed in this sea before and it vanished again some days later. Although the scientists are uncertain of its identity at the moment, they speculate that it could be a glimpse of dynamic geological processes occurring in the northern hemisphere. The study has been published in Nature Geoscience.

Titan, the largest of Saturn’s 62 moons, is an intriguing and strangely Earth-like world that has sparked great interest from scientists in recent years. It is shrouded in a thick, golden atmosphere of mostly nitrogen that is reminiscent of an early Earth and it has an extensive system of lakes, seas and rivers filled with liquid ethane and methane.

Almost a year ago, Cassini snapped a series of images of Titan including some its second-largest sea, Ligeia Mare, which were sent to the Jet Propulsion Laboratory at Caltech for processing and analysis. Whilst flicking through the images and comparing them to older data to look for any changes, researchers discovered a curious bright spot in Ligeia Mare that was not present in images taken before the July 2013 observation.

The bright feature was around 12 miles long and 6 miles wide and was located about 6 miles off the southern shore. It was present in one image taken on 10 July but it had vanished in a subsequent data set taken on 26 July. Furthermore, prior to the 10 July observation, Ligeia Mare was as still as a statue and was completely devoid of ripples or waves.

The scientists ruled out that the blob could be due to errors in the imaging equipment and have been racking their brains to come up with ideas for what it could be. Titan’s northern hemisphere is currently undergoing a transition from spring to summer, which could be responsible for the bright feature. In light of this, the team has proposed four hypotheses that they believe could explain the phenomenon.

The first idea is that waves may be picking up due to the seasonal transition; if this is the case then the image would be the first observation of deep-sea waves on this moon. Warmer weather brings with it stronger winds, therefore it is possible that as the northern hemisphere starts to heat up the winds are kicking up waves in the sea.

“The sun is shining brighter, and that energy can be powering the winds,” lead author Jason Hofgartner told The Guardian. “All you would need is a light breeze, around half a meter per second.” However, he also doubts that the winds could ever be strong enough to produce substantial waves .

Alternatively it is possible that it is some of the solid material that is in suspension in the sea, or frozen material that has started to rise to the surface as the northern hemisphere warms. Lastly, it is also feasible that it could be a surge of gas released from the sea floor which would ascend to the surface as bubbles.

“Likely, several different processes- such as wind, rain and tides- might affect the methane and ethane lakes on Titan. We want to see the similarities and differences from geological processes that occur here on Earth,” Hofgartner said in a news-release. “Ultimately, it will help us to understand better our own liquid environments here on Earth.”

Scientists have made a new material out of carbon nanotubes that moves in response to as little light as that from a torch. These new smart curtains respond to light and don't need batteries.

Curtains that move in response to light could soon be a reality thanks to research conducted at the University of California, Berkley, in the US.
A team led by associate professor Ali Javey layered carbon nanotubes, which are tiny cylindrical structures made out of carbon allotropes, onto a plastic carbonate membrane to develop a new type of material that moves in response to light.
The carbon nanotubes absorb light, convert it into heat and transfer it to the plastic membrane, causing the membrane to expand and the composite material to bend.
“The advantages of this new class of photo-reactive actuator [a system for moving or controlling a mechanism] is that it is very easy to make, and it is very sensitive to low-intensity light,” Javey explains in a news release. “The light from a flashlight is enough to generate a response.”
The researchers believe this material could be used in energy-efficient buildings, where curtains could open and close automatically throughout the day.
The results of the study were published in the journal Nature Communications. Watch the video below to see how the material works.

Quantum Switches Controlled By Single Photons

Quantum computing has the potential to revolutionize computing by exponentially increasing speed, computing power, and security as single atoms would be capable of performing tasks. Though quantum computing is probably overkill for the typical person, it holds a great deal of promise for researchers and others who need ramped up computing. A team of researchers led by Mikhail Lukin of Harvard University have demonstrated an ability to use single atoms as gates that can block the flow of electrons and can be operated with one photon. The details of the research have been described in Nature.

“Conceptually, the idea is very simple,” Lukin told the Harvard Gazette. “Push the conventional light switch to its ultimate limit. What we’ve done here is to use a single atom as a switch that, depending on its state, can open or close the flow of photons … and it can be turned on and off using a single photon.” When many switches are added together, it could essentially act like a computer.

Lukin is currently eyeing the possibility of putting this technology into fiber-optic cables, which would offer maximum security through encryption. While there are short-range possibilities with this technology, the quantum switches could increase the distance by which information could be securely transmitted from tens of kilometers up to thousands of kilometers.

The researchers developed a system that combined the photon switches with traditional vacuum tubes. “Conventional computers were initially built using vacuum tubes, and people eventually developed integrated circuits used in modern computers,” Lukin went on to say in the Harvard Gazette. “Where quantum systems stand today, the best systems are still analogous to vacuum tubes. They typically use vacuum chambers to isolate and hold single atoms using electromagnetic fields.”

Once the atoms have been captured in the vacuum tubes, lasers act like optical tweezers to hold one and then chill it nearly to absolute zero. The atom is then moved near the chip before it is blasted with microwaves and enters a state of quantum superposition. This state is so delicate that getting hit with even a single photon is capable of changing it.

These switches probably won’t see action inside a quantum network for about another decade, as there are different approaches that are more advanced, according to Jeff Thompson; a grad student who is co-author of the paper. However, these single-atom switches can interact with light that travels through optical fibers, making this next-generation computing possible.

"Green" Jet Fuel From Sunlight Developed

A consortium of research institutions and corporations have announced a solution to one of the major obstacles to a sustainable world, carbon neutral fuel for airplanes. Also fire twirling.

While political obstacles may intervene, we now have the technology to provide electricity for virtually the whole world from non-polluting sources. With the rise of electric vehicles this can be transferred to land transport as well. However, air travel was always going to be a much tougher nut to crack. With air transport the fastest growing contributor to climate change this is a large and rising issue.

Suggested solutions include used cooking oil and mustard seeds but according to Dr Andreas Sizmann of Bauhaus Luftahrt, "Increasing environmental and supply security issues are leading the aviation sector to seek alternative fuels which can be used interchangeably with today's jet fuel, so-called drop-in solutions.”

Jet fuel is made from a mixture of hydrocarbons to provide a low freezing point, anti-static and a flash point that makes it safe for transportation. However, the base is kerosene (paraffin), as used for gas camping fires and in lamps where electricity is not available. For all uses kerosene is currently produced from petroleum and predominantly made up of alkanes and naphthenes

In a quest for a travel industry that doesn't destroy the places people are trying to get to the European Union funded SOLAR-JET, bringing together five institutions in a quest to make kerosene from carbon dioxide, water and sunlight. While these substances contain all the elements required, conversion is a two-step process.

The SOLAR-JET team first converted the CO2 and H2O to a hydrogen/carbon monoxide mixture (syngas) using concentrated sunlight and metal-oxide catalysts. A technique for converting syngas to kerosene, the Fischer-Trosch process is already in widespread use.

"The solar reactor technology features enhanced radiative heat transfer and fast reaction kinetics, which are crucial for maximizing the solar-to-fuel energy conversion efficiency" says Professor Aldo Steinfeld of ETH Zurich.

The project is still at the proof-of-concept stage, and the price of fuel produced in this way is not yet clear.

The fact that kerosene can now be produced from carbon dioxide does not remove the need to phase it out from many of its current applications. Indoor kerosene use is a leading cause of respiratory disease in Africa and South Asia. Replacement with solar lamps can prevent around a million deaths each year, as well as being dramatically cheaper in the long run. Moreover, the carbon black emitted by burning kerosene is a more potent greenhouse gas than carbon dioxide, so use of kerosene made from carbon dioxide would be carbon neutral without being greenhouse neutral.

Even for air travel, a sustainable fuel will not solve all the problems. V***r trails and ozone emissions contribute almost as much to global warming as the fuel burned. Nevertheless with alternative choices for sustainable air travel in their infancy and still subject to question, the SOLAR-JET announcement could be a gamechanger if it can be done at a realistic price.

Pair of Supermassive Black Holes Spotted

For the first time in an ordinary galaxy, astronomers have spotted a hidden pair of supermassive black holes in orbit around each another. The binary system was discovered because they were ripping apart a star just as an observatory happened to be looking in their direction.

Two supermassive black holes are the smoking gun that the galaxy has merged with another. That’s because most massive galaxies (including our own) are thought to harbor at least one supermassive black hole at their center. Until now, only a few candidates have been found, and all of them have been in active galaxies where they’re ripping gas clouds apart -- a destructive process that heats up gas so much that it shines at many wavelengths. They’re labeled “active” because of the resulting bright center.

The newly discovered binary supermassive black hole -- by an international team led by Fukun Liu of Peking University -- is not in an active galaxy, but rather, an “ordinary” one. A first of its kind.

Whole populations of quiescent galaxies could be hosting binary black holes in their center, according to study coauthor Stefanie Komossa from Max-Planck-Institut für Radioastronomie. But finding them is difficult since quiescent galaxies have no gas clouds to continuously feed black holes -- which leaves these galaxies’ cores dark. Instead, black holes in quiescent galaxies are fed by “tidal disruption events” that occur sporadically. That’s when the gravity of a black hole rips a star to pieces, giving out a flare of X-rays.

The European Space Agency's X-ray Multi-Mirror Mission, XMM-Newton, was surveying the sky in a random pattern when, on 10 June 2010, it observed a tidal disruption event in the galaxy SDSS J120136.02+300305.5. Days later, the galaxy was still spilling X-rays into space.

Then something weird happened: The X-rays fell below detectable levels between days 27 and 48 after the discovery. But then they reappeared and continued to follow a more expected fading rate -- as if nothing had happened. "This is exactly what you would expect from a pair of supermassive black holes orbiting one another," Liu explains in a news release.

Liu’s models of black hole binary systems predicted a sudden plunge to darkness, followed by a recovery. The gravity of one black hole can temporarily deprive the other of its fuel to fire X-ray flares.

He calculated two possible configurations: one with an elliptical orbit, the other with a circular one. In both cases, the black holes were only separated by 0.6 milliparsecs, or about 2 thousandths of a light year. (This is about the width of the Milky Way.) Being this close means they’ll eventually spiral together, and in about two million years, they’ll merge into a single black hole.

Binary supermassive black holes can tell astronomers about how galaxies evolved into their present-day shapes and sizes. “The final merger is expected to be the strongest source of gravitational waves in the Universe," Liu says. Here, X-ray slew tracks recorded by XMM-Newton from over 1200 individuals recorded between 2001 and 2012.

Have we discovered Earth 2.0? Astronomers announced the groundbreaking discovery last week of an Earth-sized exoplanet called Kepler-186f, orbiting a star within its habitable zone. The diameter of this newly found world is just 10% bigger than Earth's. It is the first of its size found basking in the benign temperature region where water, if it exists, could pool in liquid form - which of course we know, is necessary for life. Is it too early to call this world "Earth-like"?

Is the universe balanced on a pinhead?
New precise measurements of the mass of the top quark bring back the question: Is our universe inherently unstable?

Scientists have known the mass of the heaviest fundamental particle, the top quark, since 1995.
But recent, more precise measurements of this mass have revived an old question: Why is it so huge?
No one is sure, but it might be a sign that our universe is inherently unstable. Or it might be a sign that some factor we don’t yet understand is keeping us in balance.
The top quark’s mass comes from its interaction with the Higgs field—which is responsible for the delicate balance of mass that allows matter to exist in its solid, stable form.
“The top quark is the heaviest known particle and talks the most to the Higgs field,” says Fermilab theoretical physicist Joe Lykken.
Because the top quark is deeply intertwined with the Higgs field, physicists use it as a probe to examine its properties, such as its stability under different circumstances.
But when scientist plug the measured mass of the top quark into their equations based on everything they know about the Standard Model of particle physics, something very odd happens.
“When we run the Standard Model equations up to high energies, there is a region where the Higgs field shouldn’t be there,” says CMS experimental physicist and Rice University professor Karl Ecklund. “There, the vacuum, which is normally filled with the Higgs field, could have a negative energy.”
If this prediction is correct, the Higgs field is only precariously balanced in its current state, and could at any moment topple into another, more stable one.
Any change to the Higgs field would have disastrous consequences for us, Lykken says. “The conditions for life are delicately related to the mass of elemental particles, which are related to the Higgs field. Chemistry and life would not exist if the Higgs field changed by even a small amount.”
This unstable universe idea is not new, but it had a resurgence in 2013, after the 2012 discovery of the Higgs. Now new precision measurements of the mass of the top quark based on data from both the Large Hadron Collider at CERN and the Tevatron at Fermilab have brought physicists closer to grasping whether the universe is precariously balanced between two pits of eternal chaos.
According to Ecklund, it is too soon to tell. “The mass of the top quark is right in this region where the predicted lifetime of the universe is very close to its current age, and that makes people very uncomfortable,” he says. “But if you move the top mass down and Higgs mass up, even within experimental uncertainty, this problem goes away completely.”
Even if the Higgs field is unstable, though, it could be that additional particles and forces exist that keep it steady, Ecklund says. “It might not be bad if it comes out that we are in this range of instability, because it could point to new physics we don’t know about.”
Ecklund expects that the next few runs of the LHC will help shed light on this issue by giving scientists a more precise measurement of the top quark.
“Hopefully we will cut the experimental uncertainty in half with run two of the LHC, and then in half again by end of the first run of the high-luminosity LHC,” Ecklund says. “Only then will we start to get a good enough measurement to tell one way or the other.”

http://www.symmetrymagazine.org/article/april-2014/is-the-universe-balanced-on-a-pinhead

Is the universe balanced on a pinhead? New precise measurements of the mass of the top quark bring back the question: Is our universe inherently unstable?

Almost-Earth Tantalizes Astronomers With Promise of Worlds to Come

Ever since the first exoplanet was discovered in 1996, astronomers have been scanning the heavens for another Earth: a rocky planet orbiting its star at just the right distance for it to harbor liquid water and thus, potentially, life. Now, sifting through data collected by NASA’s Kepler orbiting observatory, they have discovered just such a planet, although it’s not quite Earth 2.0. Named Kepler-186f, the planet orbits a star that is less than half the size of the sun and much cooler.

“Very exciting,” says James Kasting, an exoplanet researcher at Pennsylvania State University, University Park, who was not involved in the work. “This is probably the most potentially Earth-like planet yet.” David Charbonneau, an exoplanet researcher at Harvard University, calls it “one of the most significant discoveries from Kepler.”

The new world is the outermost of five planets orbiting Kepler-186, a red dwarf star some 500 light-years from Earth. Such M stars typically have a fraction of the mass of the sun, burn more slowly, and are too faint to be seen with the naked eye. (Hotter sunlike stars are classified as type G.) Kepler detected the planet from a minuscule dimming of the star each time the planet transited, or crossed the face of the star.

From the extent and timing of that dimming, the researchers calculated that the planet is almost the same size as Earth—just 10% bigger in diameter—and goes around its star once every 130 days. Although its mass is unknown, astronomers say its size almost guarantees that it is rocky like Earth. Its distance from its star—about as far from the star as Mercury is from the sun—puts it in the outer reaches of Kepler-186’s habitable zone.

Planets previously found in the habitable zones of other stars have been substantially larger than Earth and unlikely to have a rocky surface. But because it orbits a dwarf, “we consider this planet more of an Earth cousin than an Earth twin,” says Elisa Quintana, a researcher at NASA Ames Research Center in Mountain View, California, and lead author of a paper announcing the discovery this week in Science. Small, faint stars like type Ms make up more than three-quarters of the billions of stars in the Milky Way, however, so the finding could open a wide new hunting ground for extraterrestrial life. “Our galaxy is probably littered with cousins of Kepler-186f,” Quintana says.

Several factors could make such planets less promising abodes for life than planets circling sunlike stars. For one, their close-in habitable zones could leave them extra vulnerable to perils such as stellar flares. On the plus side, M stars keep burning billions of years longer than sunlike stars do. “That is good news for life, because there is a longer period of time for it to take hold on the surface of the planet,” says Stephen Kane, a co-author and researcher at San Francisco State University in California.

Kepler-186f is a late bonus from Kepler, which monitored the brightness of some 150,000 stars from March 2009 to May 2013 in search of planets. Analyzing Kepler data, scientists have identified more than 3800 planetary candidates, of which 961 have been confirmed as planets. As the software to search Kepler’s data improves, scientists keep finding planets that they missed before.

Researchers had detected Kepler-186’s four inner planets by the spring of 2013. Then, a routine analysis of all of Kepler’s light curves—a procedure that typically takes weeks of supercomputer time—flagged the possible existence of a small fifth planet. Quintana’s team conducted a series of checks to ensure that what the software had found was a genuine transit.

To learn more about the planet, Quintana and colleagues had to learn more about the star. By taking spectra of Kepler-186 with ground-based telescopes, they nailed down its mass and size—information that helped them determine the planet’s radius. “I remember walking to Elisa’s office one afternoon, and she looked up at me and said, ‘The planet’s about the size of the Earth,’ ” says Steve Howell, project scientist for Kepler at NASA Ames and a co-author of the paper. Further analysis placed the planet in the outer reaches of the star’s habitable zone.

“We are not saying that there’s water on the surface,” Howell says. “All we know is that the surface has the right temperature that water could exist there in a liquid state.” To support water, however, the planet would also need to have an atmosphere to protect it. It’s unclear from the available data whether the planet has an adequate atmospheric blanket.

Even those key ingredients wouldn’t guarantee that Kepler-186f is habitable. If it orbited slightly closer in, Quintana says, gravitational interactions would leave the planet tidally locked: rotating so that one side always faced the star. Such two-faced planets—with the night side eternally frigid and the day side blistering hot—are considered long shots for life. But Quintana and her colleagues say Kepler-186f is far enough out that it might avoid that fate.

Unfortunately, the planet is too far away from Earth for follow-up studies. However, researchers hope it heralds many similar worlds soon to come. “The biggest impact of this discovery is to know that there are planets that are the same size as Earth in the habitable zones of small stars,” Charbonneau says. He says the next step will be “to find a close example” so that upcoming instruments like the Giant Magellan Telescope and NASA’s James Webb Space Telescope can “study the atmosphere of such planets and perhaps even deduce the presence of life on them.”