Wednesday, August 20, 2014

Type Ia supernovae stem from the explosion of white dwarfs coupled with twin stars

Type Ia supernovae stem from the explosion of white dwarfs coupled with twin stars: A new model postulating the fusion of two white dwarfs is now challenging the predominant one, consisting of a white dwarf and a normal star. The new scenario does not imply the existence of a maximum mass limit and will not, therefore, necessarily produce explosions of similar luminosity...

"If these results were to gain general acceptance, the cosmological consequences would be weighty, because the use of type Ia supernovae to measure distances would come into question," the researcher concludes.


Thursday, August 14, 2014

Inside the cell, an ocean of buffeting waves

Inside the cell, an ocean of buffeting waves: The cytoplasm is actually an elastic gel, it turns out, so it puts up some resistance to simple diffusion. But energetic processes elsewhere in the cell—in the cytoskeleton, especially—create random but powerful waves in the cytoplasm, pushing on proteins and organelles alike. Like flotsam and jetsam buffeted by the wakes of passing ships, suspended particles scatter much more quickly and widely than they would in a calm sea.

Watch a swarm of 1000 mini-robots assemble into shapes - tech - 14 August 2014 - New Scientist

Watch a swarm of 1000 mini-robots assemble into shapes - tech - 14 August 2014 - New Scientist: To do the assembling, the desired end shape is first transmitted to all the robots and then four stationary robots are positioned by hand to mark the shape's starting point. Next, some of the robots start to shuffle until they reach a place-holding robot and then fan out from that point to stop in the right place. Each robot can only communicate with the others nearby. Successive robots build up the shape by stopping near the robots already in place. It can take about 12 hours for 1000 robots to fill in a pattern.

Monday, August 11, 2014

Scientists create artificial brain out of spongy goo | Science/AAAS | News

Scientists create artificial brain out of spongy goo | Science/AAAS | News: The rings are engineered to mimic the structure and function of the six layers of human cortical brain tissue. Scientists coaxed neurons (right) to grow around stiff, porous matrices made of silk proteins immersed in collagen gel. Then, they colored the layers with food dye and pieced them together like a jigsaw puzzle. By tweaking the size and orientation of matrix pores, researchers attempted to emulate variations of cellular structure and function in a real cortex. Unlike flat neuron cultures grown in petri dishes, the structure provides cells with something to cling to as they branch out and make connections, forming complex, 3D networks that more closely mimic real neural circuits, the authors say.

Saturday, August 9, 2014

Ask Ethan #49: Do the cosmic unknowns cast doubt on the Big Bang? — Starts With A Bang! — Medium

Ask Ethan #49: Do the cosmic unknowns cast doubt on the Big Bang? — Starts With A Bang! — Medium:  ...all isotropic, homogeneous spacetimes (that is, solutions to GR that are roughly the same at all locations in space and in all directions) must either have expanding or contracting space...

All of this — the whole story I outlined above — would be true regardless of what else is actually in your Universe. The only things that change due to dark matter and dark energy are the following...


Friday, August 8, 2014

IBM Scientists Show Blueprints for Brainlike Computing - MIT Technology Review

IBM Scientists Show Blueprints for Brainlike Computing - MIT Technology Review: “Programs” are written using special blueprints called corelets. Each corelet specifies the basic functioning of a network of neurosynaptic cores. Individual corelets can be linked into more and more complex structures—nested, Modha says, “like Russian dolls.”

Terahertz Chip Identifies Short Strands of DNA | MIT Technology Review

Terahertz Chip Identifies Short Strands of DNA | MIT Technology Review: They say that the sequence of bases in an oligonucleotide determines the way in which the strand resonates at frequencies in the terahertz range...

...they have tested it using a device they call a silicon nanosandwich, a quantum well of p-type silicon surrounded by barriers doped with boron. This produces terahertz radiation inside the well where the oligonucleotide is deposited at a concentration that allows a single molecule to enter.

Thursday, August 7, 2014

‘Unparticles’ May Hold The Key To Superconductivity, Say Physicists — The Physics arXiv Blog — Medium

‘Unparticles’ May Hold The Key To Superconductivity, Say Physicists — The Physics arXiv Blog — Medium: Georgi’s concept of unparticles comes about by conjecturing that some “stuff” may have mass, energy and momentum and yet also be scale invariant...

Physicists have long known that the behaviour of electrons in high-temperature superconductors is extremely complex...

What LeBlanc and Grushin show is that under certain conditions the interaction between these entities can become scale invariant and is therefore described by the physics of unparticles. In very simple terms, when that happens, material properties such as resistance no longer depend on the length scales involved. So if electrons move without resistance on a tiny scale, they should also move without resistance on much larger scales too. Hence the phenomenon of superconductivity.

Self-organising origami robot unfolds itself… and walks - tech - 07 August 2014 - New Scientist

Self-organising origami robot unfolds itself… and walks - tech - 07 August 2014 - New Scientist

Wednesday, August 6, 2014

Cool your jets: NASA's quantum spaceship is doubtful - space - 06 August 2014 - New Scientist

Cool your jets: NASA's quantum spaceship is doubtful - space - 06 August 2014 - New Scientist: ...as Baez points out, this new device in question wasn't even tested in a vacuum! That's extremely important; assuming the measurements are real, the thrust seen could be due to air being warmed up and moving around.

Tuesday, August 5, 2014

Physicists eye neural fly data, find formula for Zipf's law

Physicists eye neural fly data, find formula for Zipf's law: ...George Zipf... found that if you rank words in a language in order of their popularity, a strange pattern emerges: The most popular word is used twice as often as the second most popular, and three times as much as the third-ranked word, and so on. This same rank vs. frequency rule was also found to apply to many other social systems...

"We showed mathematically that the system becomes Zipfian when you're recording the activity of many units, such as neurons, and all of the units are responding to the same variable," Nemenman says. "The fact that Zipf's law will occur in a system with just 40 or 50 such units shows that biological units are in some sense special – they must be adapted to the outside world."

Monday, August 4, 2014

Don't Get Too Excited About NASA's New Miracle Engine

Don't Get Too Excited About NASA's New Miracle Engine: [The researchers] hook up a gizmo with all sorts of electromagnetic fields fluctuating around, then claim to measure an extremely tiny thrust (about the weight of a single grain of sand), which occurs even for the test article that wasn't supposed to produce any thrust at all.

Friday, August 1, 2014

Fuel-Less Space Drive May Actually Work, Says NASA | Popular Science

Fuel-Less Space Drive May Actually Work, Says NASA | Popular Science: The design is seemingly based on the EmDrive, which was originally created by British scientist Roger Shawyer. The drive is supposed to convert electric power into thrust by bouncing microwaves off the walls of a closed container, and Fetta’s drive, while different, does relatively the same thing...

In a paper presented at the 50th Joint Propulsion Conference in Cleveland, Ohio, NASA apparently gave Fetta’s design their stamp of approval after testing his drive.�Granted, their tests only produced a small amount of thrust (between 30 and�50 micro-Newtons), but that’s still pretty impressive since absolutely no propellant was needed...

He notes that these experiments are pretty easy to mess up, since you basically have to recreate the vacuum of space for the results to be right. Any interference from an outside factor could affect the results...

Wednesday, July 30, 2014

The Curious Evolution of Artificial Life | MIT Technology Review

The Curious Evolution of Artificial Life | MIT Technology Review: He divides the history of Web-based artificial life into two periods: before and after 2005, a characterization that corresponds roughly with the emergence of Web 2.0 and the collaborative behaviors that it allows.

Sunday, July 27, 2014

How bird flocks are like liquid helium | Science/AAAS | News

How bird flocks are like liquid helium | Science/AAAS | News: Using tracking software on the recorded video, the team could pinpoint when and where individuals decide to turn, information that enabled them to follow how the decision sweeps through the flock. The tracking data showed that the message to turn started from a handful of birds and swept through the flock at a constant speed between 20 and 40 meters per second. That means that for a group of 400 birds, it takes just a little more than a half-second for the whole flock to turn...

The team proposes that instead of copying the direction in which a neighbor flies, a bird copies how sharply a neighbor turns...

Interestingly, Cavagna adds, the new model is mathematically identical to the equations that describe superfluid helium.

Wednesday, July 23, 2014

Quantum split: Particle this way, properties that way - physics-math - 23 July 2014 - New Scientist

Quantum split: Particle this way, properties that way - physics-math - 23 July 2014 - New Scientist: In Grenoble, the Vienna team used a feeble magnetic field and a weakly interacting neutron absorber to make the weak measurements. They found that when they put the absorber in one path of the interferometer (say left), there was a discernible effect at the output. But when they put it in the right path, it had no such effect. The neutrons were travelling in one path only.

Next, the experimenters introduced a weak magnetic field near each arm of the interferometer, to interact with the spin of the neutrons. When they did this in the left path, there was no change in the interferometer's output. If they introduced the magnetic field in the right path, though, there was a change: the magnetic field had interacted with the spin. In other words, they had confirmed that the spin had chosen the path not taken by the parent neutron...

Black Holes Aren’t Black After All, Say Theoretical Physicists — The Physics arXiv Blog — Medium

Black Holes Aren’t Black After All, Say Theoretical Physicists — The Physics arXiv Blog — Medium: Stephen Hawking proposed a potential solution earlier this year. His idea is that gravitational collapse can never continue beyond the so-called event horizon of a black hole beyond which information is lost. Gravitational collapse would approach the boundary but never go beyond it...

Tuesday, July 22, 2014

Lasers make fibre optic tubes out of thin air - tech - 22 July 2014 - New Scientist

Lasers make fibre optic tubes out of thin air - tech - 22 July 2014 - New Scientist: The team shone four lasers in a square arrangement, heating air molecules and creating a low-density ring around a denser core of air. Light bounces around the dense core just like in a fibre.

The air fibre lasts for a few milliseconds – more than enough to send a signal.

Sunday, July 20, 2014

White holes: Hunting the other side of a black hole - space - 20 July 2014 - New Scientist

White holes: Hunting the other side of a black hole - space - 20 July 2014 - New Scientist: Perhaps the fact that we have found no signs of a white hole, despite peering ever deeper into space, is a more fundamental problem. Enter a space telescope called RadioAstron whose wildly elongated orbit takes it out to a distance of 350,000 kilometres – nearly as far as the moon and 30 times wider than Earth's diameter. Launched from Kazakhstan's Baikonur Cosmodrome in 2011, its dish is only 10 metres across. But when its signals are combined with those from radio telescopes on Earth, the resulting images are as sharp as those from a dish 350,000 kilometres wide...

"...once we spot a gigantic powerful gamma-ray burst with a lot of radio radiation, we will take a close look with RadioAstron and try to determine its shape and size for the first time." That could provide important clues about its source. "It may be a white hole or a wormhole. Maybe the flashes are coming from another universe."

Thursday, July 17, 2014

Quantum bounce could make black holes explode : Nature News & Comment

Quantum bounce could make black holes explode : Nature News & Comment: The theory suggests that the transition from black hole to white hole would take place right after the initial formation of the black hole, but because gravity dilates time, outside observers would see the black hole lasting billions or trillions of years or more, depending on its size. If the authors are correct, tiny black holes that formed during the very early history of the Universe would now be ready to pop off like firecrackers and might be detected as high-energy cosmic rays or other radiation. In fact, they say, their work could imply that some of the dramatic flares commonly considered to be supernova explosions could in fact be the dying throes of tiny black holes that formed shortly after the Big Bang.

Wednesday, July 16, 2014

Cosmologists Prove Negative Mass Can Exist In Our Universe — The Physics arXiv Blog — Medium

Cosmologists Prove Negative Mass Can Exist In Our Universe — The Physics arXiv Blog — Medium: Today, Saoussen Mbarek and Manu Paranjape at the Université de Montréal in Canada say they’ve found a solution to Einstein’s theory of general relativity that allows negative mass without breaking any essential assumptions. Their approach means that negative mass can exist in our universe provided there is a reasonable mechanism for producing it, perhaps in pairs of positive and negative mass particles in the early universe...

The crucial breakthrough by Mbarek and Paranjape is to show that negative mass can produce a reasonable Schwarzschild solution without violating the energy condition. Their approach is to think of negative mass not as a solid object, but as a perfect fluid, an otherwise common approach in relativity...

Meet the electric life forms that live on pure energy - life - 16 July 2014 - New Scientist

Meet the electric life forms that live on pure energy - life - 16 July 2014 - New Scientist: Unlike any other living thing on Earth, electric bacteria use energy in its purest form – naked electricity in the shape of electrons harvested from rocks and metals...

First they measure the natural voltage across the sediment, before applying a slightly different one. A slightly higher voltage offers an excess of electrons; a slightly lower voltage means the electrode will readily accept electrons from anything willing to pass them off. Bugs in the sediments can either "eat" electrons from the higher voltage, or "breathe" electrons on to the lower-voltage electrode, generating a current. That current is picked up by the researchers as a signal of the type of life they have captured...

"This is huge. What it means is that there's a whole part of the microbial world that we don't know about..."


Tuesday, July 15, 2014

New Material, Darker Than Black, Could Help Space Cameras See Better | Popular Science

New Material, Darker Than Black, Could Help Space Cameras See Better | Popular Science: Scientists make Vantablack by depositing carbon nanotubes close together on a thin sheet of aluminum. The tiny spaces between the tubes trap light, preventing it from reflecting off the material. A number of research groups have made super-absorbing black materials with similar microstructures. One advantage of Vantablack is that it doesn't require as high of temperatures to make as other carbon nanotube materials, according to Surrey NanoSystems. That means engineers can deposit Vantablack coatings on a wider range of materials.

Monday, July 14, 2014

First boron buckyballs roll out of the lab - physics-math - 14 July 2014 - New Scientist

First boron buckyballs roll out of the lab - physics-math - 14 July 2014 - New Scientist: ...made a cage-like molecule with 40 boron atoms by vaporising a chunk of boron with a laser then freezing it with helium, creating boron clusters. The team analysed the energy spectra of these clusters... The matching configuration revealed they had created the boron ball.

Unlike carbon buckyballs, in which the faces are made of hexagons and pentagons, the boron buckyball is made from triangles, hexagons and heptagons. As a result, it is less spherical but still an enclosed structure. Wang has dubbed the molecule "borospherene".

Friday, July 11, 2014

How to Build an Evryscope | MIT Technology Review

How to Build an Evryscope | MIT Technology Review: Their new gigapixel-scale telescope will be capable of photographing the entire sky simultaneously and continuously at relatively low cost...

It consists of 23 small telescopes mounted on a hemispherical dome that can rotate to track the sky. Each small telescope has a 7 cm aperture and a field of view of a few hundred square degrees. Each one focuses light onto 29 megapixel chip.

The dome is designed so that the fields of view of each of the small telescopes overlap to cover around 10,000 square degrees of sky simultaneously and to produce 0.7 gigapixel images. The dome rotates on equatorial mount so that the Evryscope can record exposures of up to 3 hours before ratcheting back and tracking the next sky area.

Tuesday, July 8, 2014

Harnessing the speed of light | MIT News Office

Harnessing the speed of light | MIT News Office: One of Fang’s key discoveries is finding how to beat the diffraction of light. Since light and sound waves tend to spread out when blocked by an obstacle, images and communication signals can become blurry and muddled. In his lab, Fang discovered that by breaking the diffraction barrier, light signals can be sent at 10 times greater capacity. This has allowed him to produce results on the sub-nanometer scale, with light as a machining tool providing “a new degree of precision,” he says.

Monday, July 7, 2014

Seeker, Doer, Giver, Ponderer - NYTimes.com

Seeker, Doer, Giver, Ponderer - NYTimes.com: James H. Simons... His passion... is basic research — the risky, freewheeling type. He recently financed new telescopes in the Chilean Andes that will look for faint ripples of light from the Big Bang, the theorized birth of the universe.

The afternoon of the interview, he planned to speak to Stanford physicists eager to detect the axion, a ghostly particle thought to permeate the cosmos but long stuck in theoretical limbo.

Tractor Beam Created Using Water Waves� — The Physics arXiv Blog — Medium

Tractor Beam Created Using Water Waves� — The Physics arXiv Blog — Medium: This fluid jet carries any floating particles along with the waves...

But as the waves get bigger, they become unstable and their behaviour changes dramatically...

Punzmann and co say the interaction between the waves in this non-linear regime changes the direction of the jet at the centre of the wave maker. “It now pushes floaters inward, towards the wave maker and against the wave propagation,” they say. Any floaters caught in this jet, are therefore pulled.

To test this idea, Punzmann and co have recreated exactly this situation in a wave tank with an elongated wave maker. They place a ping-pong ball on the water and then measure its movement as well as the shape of the water surface and the fluid flow on the surface.

Sure enough, when the amplitude of the waves is small, the ping-pong ball moves in the same direction as the waves. But as the waves become larger, the ping-pong ball reverses direction and moves back towards the wave maker...

Friday, July 4, 2014

Tiny waves could build livers on a 'liquid template' - tech - 04 July 2014 - New Scientist

Tiny waves could build livers on a 'liquid template' - tech - 04 July 2014 - New Scientist: After adding a handful of starter pieces, such as silicon chips or small plastic beads, the researchers tuned the generator to various frequencies to create waves in the solution. Depending on their surface chemistry, the added particles spontaneously collected in either the crests or the valleys. Retuning the generator let the team switch between multiple patterns...

He and his colleagues cultured mouse cells and put them in the liquid template. The cells collected into little spheres that became the building blocks of larger geometric patterns. Adding blood clotting proteins to the saline solution locked the cells in place, an approach that the team is now investigating for growing liver tissue.

Thursday, July 3, 2014

Elastic Cloaking Material Makes Objects “Unfeelable” - Scientific American

Elastic Cloaking Material Makes Objects “Unfeelable” - Scientific American: The unfeelability cloak is a so-called pentamode metamaterial, an artificial structure that, despite being a solid, can behave like a fluid; although difficult to compress, its shape is otherwise easy to shift. The specific material the researchers devised is a three-dimensional hexagonal lattice reminiscent of a honeycomb, with the rods making up this lattice wider at their middles than at their ends...

The unfeelability cloak does have limits. For instance, the dimensions of the cloak's components have to be designed to specifically match whatever the cloak is hiding. Furthermore, although unfeelability cloaks can hide objects from some pokes and prods, it cannot protect against all of them—one can push on a cloak strongly enough to break it and feel the object it hides.

Wednesday, July 2, 2014

Hollow optical fibers for UV light

Hollow optical fibers for UV light: Researchers... have tested a new type of optical fibre with a hollow core and have found out that this type of optical fibre was able to guide UV laser light without being damaged and with acceptable loss.

Tuesday, July 1, 2014

A perfect negative crystal floating in space - 01 July 2014 - New Scientist

A perfect negative crystal floating in space - 01 July 2014 - New Scientist: The octahedron is the outline of a space, and what looks at first like the sides of a solid crystal are actually the walls of a void inside a bigger lump of crystal.

New metamaterial gives light a one-way ticket

New metamaterial gives light a one-way ticket:  ...The silver-glass structure is an example of a "hyperbolic" metamaterial, which treats light differently depending on which direction the waves are traveling...

While the second set of grates let light escape the material, their spacing was slightly different from that of the first grates. As a result, the reverse-direction grates bent incoming light either too much or not enough to propagate inside the silver-glass layers. Testing their structures, the researchers found that around 30 times more light passed through in the forward direction than in reverse, a contrast larger than any other achieved thus far with visible light.

Combining materials that could be made using existing methods was the key to achieving one-way transmission of visible light, Lezec says. Without the intervening silver-and-glass blocks, the grates would have needed to be fabricated and aligned more precisely than is possible with current techniques. "This three-step process actually relaxes the fabrication constraints," Lezec says.

Monday, June 30, 2014

Study helps unlock mystery of high-temp superconductors

Study helps unlock mystery of high-temp superconductors: "Evidence has been accumulating that this phase supports an exotic density wave state that may be key to its existence...". A density wave forms in a metal if the fluid electrons themselves crystalize.
Using a scanning tunneling microscope (STM) to visualize the electronic structure of the oxygen sites within a superconductor, the team found a density wave with a d-orbital structure. (The electron density near each copper atom looks a bit like a daisy in the crystallized pattern.) That's especially surprising because most density waves have an s-orbital structure; their electron density is isotropic. "It's not the pattern you would expect," Lawler says.
In this research, Lawler and his colleagues focused on a member of the cuprate class of superconductors called bismuth strontium calcium copper oxide (BSCCO). "We now believe these density waves exist in all cuprates," says Lawler, a theorist whose contribution to the research involved subtle uses of the Fourier transform, a mathematical analysis that's useful when examining amplitude patterns in waves.

Muscle-powered bio-bots walk on command | News Bureau | University of Illinois

Muscle-powered bio-bots walk on command | News Bureau | University of Illinois: The new bio-bots are powered by a strip of skeletal muscle cells that can be triggered by an electric pulse...

“Skeletal muscles cells are very attractive because you can pace them using external signals,” Bashir said. “For example, you would use skeletal muscle when designing a device that you wanted to start functioning when it senses a chemical or when it received a certain signal. To us, it’s part of a design toolbox. We want to have different options that could be used by engineers to design these things.”

The design is inspired by the muscle-tendon-bone complex found in nature. There is a backbone of 3-D printed hydrogel, strong enough to give the bio-bot structure but flexible enough to bend like a joint. Two posts serve to anchor a strip of muscle to the backbone, like tendons attach muscle to bone, but the posts also act as feet for the bio-bot.


Sunday, June 29, 2014

Noninvasive brain control | MIT News Office

Noninvasive brain control | MIT News Office: MIT engineers have now developed the first light-sensitive molecule that enables neurons to be silenced noninvasively, using a light source outside the skull...

Boyden’s team had previously identified two light-sensitive chloride ion pumps that respond to red light, which can penetrate deeper into living tissue. However, these molecules, found in the bacteria Haloarcula marismortui and Haloarcula vallismortis, did not induce a strong enough photocurrent — an electric current in response to light — to be useful in controlling neuron activity.

Chuong set out to improve the photocurrent by looking for relatives of these proteins and testing their electrical activity. She then engineered one of these relatives by making many different mutants. The result of this screen, Jaws, retained its red-light sensitivity but had a much stronger photocurrent — enough to shut down neural activity.

Single-pixel 'multiplex' captures elusive terahertz images

Single-pixel 'multiplex' captures elusive terahertz images: The team reports it developed a "multiplex" tunable spatial light modulator (SLM) that uses a series of filter-like "masks" to retrieve multiple samples of a terahertz (THz) scene, which are reassembled by a single-pixel detector...

Data obtained from these encoded measurements are used to computationally reconstruct the images as much as six times faster than traditional raster scan THz devices, the team reports.

Thursday, June 26, 2014

Is time moving forward or backward? Computers learn to spot the difference | Science/AAAS | News

Is time moving forward or backward? Computers learn to spot the difference | Science/AAAS | News: To find out, she and her collaborators broke down 180 YouTube videos into square patches of a few hundred pixels, which they further divided into four-by-four grids. Combining standard techniques for discovering objects in still photographs with motion detection algorithms, the researchers identified 4000 typical patterns of motion, or “flow words,” across a grid’s 16 cells. The gentle downward drifting of snowflakes, for example, would be one flow word. From those patterns, the team created flow word descriptions of each video along with three other versions—a time-reversed version, a mirror-image version, and a mirror-image and time-reversed version. Then, they made a computer program watch 120 of these clips, training it to identify which flow words best revealed whether a video ran forward or backward.

When they tested their program on the remaining 60 videos, the trained computers could correctly determine whether a video ran forward or backward 80% of the time...  A closer analysis found that flow words associated with divergence (water splashing outward as someone dives into a pool) or dissipation (a steam train’s exhaust spreading out in air) were especially good indicators of the direction in which time was moving.


Cambridge team breaks superconductor world record

Cambridge team breaks superconductor world record: The Cambridge researchers managed to 'trap' a magnetic field with a strength of 17.6 Tesla - roughly 100 times stronger than the field generated by a typical fridge magnet - in a high temperature gadolinium barium copper oxide (GdBCO) superconductor, beating the previous record by 0.4 Tesla...

In order to hold in, or trap, the magnetic field, the researchers had to modify both the microstructure of GdBCO to increase its current carrying and thermal performance, and reinforce it with a stainless steel ring, which was used to 'shrink-wrap' the single grain samples. "This was an important step in achieving this result..."

...by engineering the bulk microstructure, the field is retained in the sample by so-called 'flux pinning centres' distributed throughout the material...

Wednesday, June 25, 2014

Embrace the lumpiverse: How mess kills dark energy - physics-math - 25 June 2014 - New Scientist

Embrace the lumpiverse: How mess kills dark energy - physics-math - 25 June 2014 - New Scientist: Wiltshire takes issue with the last of the motions used to make the dipole anisotropy disappear: a movement at a speed of 635 kilometres per second of the entire Local Group towards a "great attractor" somewhere in the distant Hydra-Centaurus supercluster of galaxies...

They claim the galaxies' movements make most sense if the Local Group isn't moving at all. Instead, the greater density of matter towards Hydra-Centaurus is slowing the universe's expansion along our line of sight, giving us the impression of such a movement. A comparative void in the other direction, meanwhile, is producing the opposite effect, causing an area of faster expansion behind us. The effects of the inhomogeneities along this axis are comparatively local, occurring on scales up to about 300 million light years, and only alter the universe's expansion rate by some 0.5 per cent. But they are sufficient to account for nearly all of the dipole anisotropy – and so colour our view of the entire universe...

This suggests that the age of the universe could be as much as 18.6 billion years in places where a low density of matter means the clock has ticked particularly fast. Our own smaller estimate of the universe's age is a natural consequence of sitting in an area of unusually high density: a galaxy.

Monday, June 23, 2014

First Evidence Of A Correction To The Speed of Light — The Physics arXiv Blog — Medium

First Evidence Of A Correction To The Speed of Light — The Physics arXiv Blog — Medium: Because all previous speed-of-light calculations have relied only on general relativity, they do not take into account the tiny effects of quantum mechanics. But these effects are significant over such long distances and through such a large mass as the Milky Way, says Franson...

Franson’s idea is that the gravitational potential must influence the electron-positron pair because they have mass. “Roughly speaking, the gravitational potential changes the energy of a virtual electron-positron pair, which in turn produces a small change in the energy of a photon,” he says. “This results in a small correction to the angular frequency of a photon and thus its velocity.”

Clingy dark matter may slow the spin of corpse stars - physics-math - 23 June 2014 - New Scientist

Clingy dark matter may slow the spin of corpse stars - physics-math - 23 June 2014 - New Scientist: Their strong magnetic fields gradually slow their spin, but over the past 15 years, astronomers have noticed that many pulsars are slowing more than we would expect.

Chris Kouvaris at the University of Southern Denmark thinks a form of dark matter with a tiny electric charge may be putting on the brakes.

Equations reveal the rebellious rhythms at the heart of nature

Equations reveal the rebellious rhythms at the heart of nature: Physicists Dmytro Iatsenko , Professor Peter McClintock, and Professor Aneta Stefanovska, have reported a far more general solution of the Kuramoto equations than anyone has achieved previously, with some quite unexpected results.

One surprise is that the oscillators can form "glassy" states, where they adjust the tempos of their rhythms but otherwise remain uncoordinated with each other, thus giving birth to some kind of "synchronous disorder" rather like the disordered molecular structure of window glass. Furthermore and even more astonishingly, under certain circumstances the oscillators can behave in a totally independent manner despite being tightly coupled together, the phenomenon the authors call "super-relaxation".

Friday, June 20, 2014

New test may provide 'smoking gun' for modified gravity

New test may provide 'smoking gun' for modified gravity: Now in a new paper published in Physical Review Letters, Wojciech A. Hellwing, et al., have proposed a new test of modified gravity that is based on measuring the tendency of well-separated galaxies to approach each other. This movement is called the galaxy pairwise velocity.
The physicists show that the galaxy pairwise velocity distribution of many galaxies with a wide range of masses is expected to deviate from the predictions of general relativity by significant amounts: between 5 and 10 standard deviations or higher, depending on the model. Due to these large deviations, this proposed test could potentially offer the strongest evidence in support of modified gravity to date.

Sound sieve lets you choose what to levitate - tech - 20 June 2014 - New Scientist

Sound sieve lets you choose what to levitate - tech - 20 June 2014 - New Scientist: The team etched a thin brass plate with rectangular strips and suspended it in a tank of water. Ultrasound blasted from above sends acoustic waves through the water that cause the plate to resonate with the bottom of the tank. The resulting sound pressure lifts objects placed below the plate according to size and density.

The team sorted small glass beads from larger ones and pulled glass beads away from tin beads of the same size...

Elastic invisibility cloak hides materials from touch sense

Elastic invisibility cloak hides materials from touch sense: The metamaterial is a crystalline material structured with sub-micrometer accuracy. It consists of needle-shaped cones, whose tips meet. The size of the contact points is calculated precisely to reach the mechanical properties desired. In this way, a structure results, through which a finger or a measurement instrument cannot feel its way.

In the invisibility cloak produced, a hard cylinder is inserted into the bottom layer. Any objects to be hidden can be put into its cavity. If a light foam or many layers of cotton would be placed above the hard cylinder, the cylinder would be more difficult to touch, but could still be felt as a form. The metamaterial structure directs the forces of the touching finger such that the cylinder is hidden completely...

Thursday, June 19, 2014

Quantum Method Closes in on Gravitational Constant - Scientific American

Quantum Method Closes in on Gravitational Constant - Scientific American; Researchers have been unable to identify the source of errors causing the disagreement in the conventional measurements. The set-up of the latest measurement is unlikely to contain the same errors as the torque method...

In the experiment described by Tino’s team, pulses of laser light tickle a cloud of rubidium atoms cooled to nearly absolute zero, driving the atoms to rise and fall like a fountain under the influence of gravity. The pulses split the 'matter wave' associated with each atom into a superposition of two energy states, each of which has a different velocity and reaches a different height — 60 or 90 centimeters — before falling back. The matter wave that rises farthest has a greater separation from the tungsten cylinders, and thus senses a slightly different gravitational pull. The difference in force imparts a measurable shift in the final state of the two matter waves when they recombine, creating an interference pattern.

Big Bang breakthrough team back-pedals on major result - physics-math - 19 June 2014 - New Scientist

Big Bang breakthrough team back-pedals on major result - physics-math - 19 June 2014 - New Scientist: The paper published today is significant because it is the first time the researchers themselves have dialled back on their original claims...

"It seems that real data from Planck is indicating that these dust models are under-estimates," says Pryke. "The prior knowledge of dust at these latitudes in our field of view has gone up and so the confidence in the gravitational wave component has gone down."

New ultrastiff, ultralight material developed | MIT News Office

New ultrastiff, ultralight material developed | MIT News Office: The actual production of such materials is made possible by a high-precision 3-D printing process called projection microstereolithography...

“We found that for a material as light and sparse as aerogel [a kind of glass foam], we see a mechanical stiffness that’s comparable to that of solid rubber, and 400 times stronger than a counterpart of similar density. Such samples can easily withstand a load of more than 160,000 times their own weight,” says Fang...