For a variety of obvious reasons, it’s impossible to reproduce the exact environment in which galaxies form. The lack of direct experimental tests for a the models astrophysicists use creates a disconnect between what astronomers observe and theoretical work. However, that barrier is being broken down by a combination of high-powered lasers and a new understanding of how lab-scale experiments can be related to vastly larger systems such as galaxies.

Researchers at the Laboratoire pour l’Utilisation de Lasers Intenses (LULI), along with colleagues at various universities, have successfully simulated the magnetic fields that form in early galaxies. Naively, there seems to be no correspondence between the experiment and the real astrophysical system. The lab set-up is very small, works on a very short time frame, and uses carbon rods and lasers; the real environment for galaxy formation is clouds of gas and dark matter, and the time-scale is hundreds of millions of years. Nevertheless, a magnetic field strength (along with other effects) has been observed in the lab that corresponds to that experienced by early protogalaxies.

(via Bringing galaxy-scale magnetic fields down to size in the lab)

The Event Horizon Telescope is an Earth-sized virtual telescope powerful enough to see all the way to the center of our Milky Way, where a supermassive black hole will allow astrophysicists to put Einstein’s General Theory of Relativity to the test.

Astronomers, physicists and scientists from related fields across the world will convene in Tucson, Ariz. on Jan. 18 to discuss an endeavor that only a few years ago would have been regarded as nothing less than outrageous.

The conference is organized by Dimitrios Psaltis, an associate professor of astrophysics at the University of Arizona’s Steward Observatory, and Dan Marrone, an assistant professor of astronomy at Steward Observatory. “Nobody has ever taken a picture of a black hole,” Psaltis said. “We are going to do just that.”

(via Scientists Prepare to Take First-Ever Picture of a Black Hole | UANews.org)

Astronomers using data from NASA’s Kepler mission have discovered the three smallest planets yet detected orbiting a star beyond our sun. The planets orbit a single star, called KOI-961, and are 0.78, 0.73 and 0.57 times the radius of Earth. The smallest is about the size of Mars.

All three planets are thought to be rocky like Earth but orbit close to their star, making them too hot to be in the habitable zone, which is the region where liquid water could exist. Of the more than 700 planets confirmed to orbit other stars, called exoplanets, only a handful are known to be rocky.

“Astronomers are just beginning to confirm the thousands of planet candidates uncovered by Kepler so far,” said Doug Hudgins, Kepler program scientist at NASA Headquarters in Washington. “Finding one as small as Mars is amazing, and hints that there may be a bounty of rocky planets all around us.”

Kepler searches for planets by continuously monitoring more than 150,000 stars, looking for telltale dips in their brightness caused by crossing, or transiting, planets. At least three transits are required to verify a signal as a planet. Follow-up observations from ground-based telescopes also are needed to confirm the discoveries.

The latest discovery comes from a team led by astronomers at the California Institute of Technology in Pasadena. The team used data publicly released by the Kepler mission, along with follow-up observations from the Palomar Observatory, near San Diego, and the W.M. Keck Observatory atop Mauna Kea in Hawaii. Their measurements dramatically revised the sizes of the planets from what was originally estimated, revealing their small nature.

The three planets are very close to their star, taking less than two days to orbit around it.The KOI-961 star is a red dwarf with a diameter one-sixth that of our sun, making it just 70 percent bigger than Jupiter. (via NASA’s Kepler Mission Finds Three Smallest Exoplanets - NASA Jet Propulsion Laboratory)

Researchers at the University of Warwick and Oxford University have developed a form of crystal that can deliver highly accurate temperature readings, down to individual milli-kelvins, over a very broad range of temperatures: -120 to +680 degrees centigrade.

The researchers used a “birefringent” crystal which splits light passing through it into two separate rays. Research has already shown that the size of the effect will increase or decrease in proportion to the temperature of the crystal. Therefore, in theory, you could calibrate such crystals to be highly accurate temperature gauges.

However, the use of birefringence in this way has significant problems in practice. This temperature measuring ability of highly birefringent crystals is badly compromised by changes in the thickness and orientation of the crystal. This adds expense to the manufacture and calibration of such crystals and makes them almost unusable in situations where, for example, vibration could alter the orientation of the crystal.

However the Warwick and Oxford researchers have developed a reproducible and low-cost method of modifying the properties of crystalline lithium tantalate so that its birefringence is virtually independent of the crystal’s thickness and position making it resistant to vibration and cheaper to manufacture. In fact, they have made the birefringence almost zero in magnitude in all directions (the material is close to being optically isotropic just like ordinary glass). However, the slightest temperature change induces a rapid increase in birefringence in these materials, making this a reliable, robust and very sensitive method for measuring temperature. The inventors have named their device a Zero-Birefringence Optical Temperature Sensor (Z-BotS) and are currently seeking follow-on funding to develop the device from the bench-top proof-of-concept to a miniaturized commercially-viable package.

(via Research gives crystal clear temperature readings from toughest environments)

A thin sheet of plastic has been making headlines at Princeton as a magical flying carpet, after the publication of a paper describing experiments by the team with their prototype sheet of plastic that uses piezoelectric actuators and sensors to move. The sensors and conducting threads create “ripples” of air moving front to back of the sheet, and the sheet is propelled into the air.

(via ‘Flying carpet’: Princeton team’s plastic sheet can hover above ground (w/ video))

(via Cigarette butts to the left, fishing rope to the right, plastic everywhere: what I found on the beach over a year. | Guest Blog, Scientific American Blog Network)

sugaratoms:

ANU scientists have successfully bent light beams around an object on a two dimensional metal surface, opening the door to faster and cheaper computer chips working with light.

The international team, including three members from the Research School of Physics and Engineering at ANU, have successfully demonstrated that a tiny beam of light on a flat surface can be bent around an obstacle, and course-correct itself on the other side of that obstacle. It’s the world’s first two-dimensional demonstration of so-called ‘Airy beams’. Their paper on the subject will be published in this month’s Physical Review Letters.

“Students in science class learn that light rays travel along straight trajectories and that it can’t go around corners,” said ANU team member Professor Yuri Kivshar.

“Recently it was discovered that small beams of light can be bent in a laboratory setting, diffracting much less than a regular beam. These rays of light are called ‘Airy Beams,’ and named after the English astronomer Sir George Biddell Airy, who studied light in rainbows.

“Our team has demonstrated that these beams can also be bound on the flat surface of a chip. We also observed a fascinating property of these beams – the so-called self-healing phenomenon, where the wave recovers after passing through surface defects,” he said.

Fellow ANU team member Dr Dragomir Neshev says that this demonstration offers potential in a number of areas.

“This discovery offers some exciting possible applications, particularly in the area of communications technology where it could allow us a cheap way to manipulate light on a chip,” he said.

vruz:

NPR: Hubble Captures Time-Lapse Videos Of Stars Being Born

—via project-argus:(Movies of jets from young stars at HubbleSite: here)

(via mariposima)

Most of the renewable energy sources that are under consideration involve an obvious source of energy—light, heat, or motion. But this is the second time this year there has been a paper that has focused on a less obvious source: the potential difference between fresh river water and the salty oceans it flows into. But this paper doesn’t simply use the difference to produce some electricity; instead, it adds bacteria to the process and takes out a portable fuel: hydrogen.

The process is still fundamentally electrochemical. Sea water and fresh water are placed on opposite sides of a membrane that allows ions through, but prevents the passage of water molecules. The ions will move to the fresh water to balance osmotic forces, which will create a charge difference that can be harvested for various purposes. The voltage produced in a single one of these cells is small, but the source of the power is essentially unlimited and is available 24 hours a day.

The small voltage per cell, however, makes this an impractical method of producing hydrogen by splitting water. It’s possible to reach the requisite voltages if enough of these cells are placed in series, but this requires dozens of them, and so many membranes that the cost of this sort of apparatus is prohibitive.

That’s where the bacteria come in. When given a source of organic material, the bacteria will harvest its electrons by oxidizing the carbon and convert their energy into the cell’s main power supply, ATP. But they have to put those electrons somewhere. If they lack a convenient electron acceptor, they’ll use an inconvenient one, even if it happens to be outside the cell (this is the principle behind the uranium-munching bacteria we discussed recently). Hook the bacteria up to an electrode, and they’ll push their electrons into that.

(via Fresh water salt water bacteria = renewable energy)

I don’t know about you, but when I think of lasers, I think of boxes on heavy, stabilized tables. Inside the boxes, the optical elements are mounted on stabilized mounts and everything is generally held as solidly in place as possible. The one thing that you generally don’t do is give a laser a good shaking. Unless it has already stopped working, in which case, have at it… preferably with a hammer.

Finding a paper that demonstrated a laser with better performance when it was being shaken compared to when it was held came as a bit of a shock.

The reason why the idea of shaking a laser is so shocking to me is that the lasers I am used to working with have optical elements that need to maintain a precise alignment with respect to one another. Temperature changes, vibrations, shaking, and “thumping the box to fix it” are all really bad ideas. But of course not all lasers are like this.

The laser in your laser pointer, CD, DVD, and Blu-Ray players are all monolithic devices. That is, they are made from a single piece of material, or materials, that are deposited on one another. You can obviously shake a laser pointer (much to the delight of cats), but this capability doesn’t scale. If you were to shake a laser pointer with acoustic waves that had a wavelength about the same size as the device (in the GHz range), then I would expect that things would probably go wrong rather quickly.

In most cases, at least. A group of researchers from Germany and Russia have now made a laser that works better when it is shaken. The reason why this occurs lies in the peculiar nature of the laser used by the researchers.

The laser that the researchers worked with was made from quantum dots (see side bar) embedded in a semiconductor material that had mirrors deposited on either side of it. This means that the distance between the two mirrors was extremely short. The researchers don’t state how big the distance was, but from the figures, I estimate that it wasn’t much longer than eight micrometers. For comparison, the wavelength emitted by the quantum dots was around 900nm.

(via A laser that works better shaken, not stirred)

Cloaking devices are one of the inventions of science fiction that have made a few tentative steps towards the real world in recent years. Now, researchers have moved the concept into the fourth dimension, creating a setup that hides a specific point in time from being perceived by observers. But if you want to make an event disappear, you have to act fast: right now, we can only hide a few picoseconds worth of time.

The cloaking devices we’ve made all work based on a similar principle: light that enters the device is bent in such a way that when it exits, its location and direction make it appear that the device itself, and anything within it, were not present. In other words, while within the device, light travels as if it were present. It’s just that, once it exits the other side, there’s no evidence that anything unusual has taken place. The same general idea governs the action of a temporal cloaking device.

The basic idea is that, when it’s not in operation, a light beam can pass through the cloaking device unhindered. When it’s switched on, a short temporal gap is opened up in the beam, then sealed back up on its way out of the hardware. One way to think of this is to view the light beam as a bit of old-fashioned magnetic tape. You can cut the tape so that a single instant of a recording can be physically separated. While separated, you can pass anything you want through the gap, but when you glue the tape back together, the recording is seamless. There’s only a before and after while the tape is cut and separated.

It’s easy to do that with tape, but a bit harder to do it with a beam of light. The key to the process is what’s being termed a split time lens, which is matched with a dispersive medium. When activated, the lens takes the light that comes before the point of cloaking and shifts it to bluer wavelengths, which travel faster through the dispersive medium than the base speed of the light in the same medium. At the cloak point, the lens switches, shifting the light beam to longer, redder wavelengths. These travel through the dispersive medium more slowly.

(via Optical setup helps researchers hide an event from time)

The 2011 Nobel Prize in chemistry was awarded to Dan Schechtman for his discovery of quasicrystals, materials that do not have the regular lattice structure of crystalline solids. Schechtman produced quasicrystals in the laboratory in 1982, but until 2008 nobody had found a naturally occurring quasicrystal. Now researchers in Italy and the United States have examined the rock that contained these natural quasicrystals and determined it may actually be part of a meteorite.

Normal crystalline solids have atoms or molecules arranged in cubes, hexagons, or other regular repeating patterns. Quasicrystals exhibit different symmetries that never precisely repeat: pentagons, icosahedrons, and so forth. Schechtman and researchers after him produced these quasi-periodic lattices by melting materials under high pressure, then cooling them quickly in a process known as quenching.

In 2008, Luca Bindi of the Museo di Storia Naturale in Firenze, Italy approached Paul Steinhardt at Princeton University to investigate a curious rock collected in eastern Russia during the late 1970s. The researchers (including Bindi, Steinhardt, Nan Yao, and Peter Lu) found it contained naturally occurring quasicrystal grains—the first ever identified.

(via The quasicrystal that fell to Earth)

As a quantum theory of gravity, loop quantum gravity could potentially solve one of the biggest problems in physics: reconciling general relativity and quantum mechanics. But like all tentative theories of quantum gravity, loop quantum gravity has never been experimentally tested. Now in a new study, scientists have found that, when black holes evaporate, the radiation they emit could potentially reveal “footprints” of loop quantum gravity, distinct from the usual Hawking radiation that black holes are expected to emit.

In this way, evaporating black holes could enable the first ever experimental test for any theory of quantum gravity. However, the proposed test would not be easy, since scientists have not yet been able to detect any kind of radiation from an evaporating black hole.

The scientists, from institutions in France and the US, have published their study called “Probing Loop Quantum Gravity with Evaporating Black Holes” in a recent issue of Physical Review Letters.

“For decades, Planck-scale physics has been thought to be untestable,” coauthor Aurélien Barrau of the French National Institute of Nuclear and Particle Physics (IN2P3) told PhysOrg.com. “Nowadays, it seems that it might enter the realm of experimental physics! This is very exciting, especially in the appealing framework of loop quantum gravity.”

In their study, the scientists have used algorithms to show that primordial black holes are expected to reveal two distinct loop quantum gravity signatures, while larger black holes are expected to reveal one distinct signature. These signatures refer to features in the black hole’s energy spectrum, such as broad peaks at certain energy levels.

Using Monte Carlo simulations, the scientists estimated the circumstances under which they could discriminate the predicted signatures of loop quantum gravity and those of the Hawking radiation that black holes are expected to emit with or without loop quantum gravity. They found that a discrimination is possible as long as there are enough black holes or a relatively small error on the energy reconstruction.

While the scientists have shown that an analysis of black hole evaporation could possibly serve as a probe for loop quantum gravity, they note that one of the biggest challenges will be simply detecting evaporating black holes.

“We should be honest: this detection will be difficult,” Barrau said. “But it is far from being impossible.”

(via Physicists propose test for loop quantum gravity)

architizer:

“Three Cubes Colliding,” an experimental kite made of carbon fiber, aerospace fabric and 3D-printed connectors that challenges notions of airborne architecture.