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.

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.

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.

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...

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.

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.

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."

Create the ultimate world clock with a quantum link - physics-math - 15 June 2014 - New Scientist

Create the ultimate world clock with a quantum link - physics-math - 15 June 2014 - New Scientist: Timekeeping institutes around the world each have their own caesium clocks. They submit their time signal measurements to the International Bureau of Weights and Measures in Paris, France, which averages them and publishes a monthly newsletter that sets Coordinated Universal Time (UTC). But that means there is no real-time measure of a universally agreed standard time...

...The team calculates that a global quantum clock network would be about 100 times more precise than any individual clock...

New Double Helix Visualization Revises What We Know About DNA

New Double Helix Visualization Revises What We Know About DNA: Results reaffirmed the structure first suggested by Watson and Crick in 1953. But surprisingly, the single-molecule images showed major variations in the depths and grooves in the double helix structure.

Blockbuster Big Bang Result May Fizzle, Rumor Suggests | Science/AAAS | News

Blockbuster Big Bang Result May Fizzle, Rumor Suggests | Science/AAAS | News: To subtract the galactic foreground, BICEP researchers relied on a particular map of it generated by the European Space Agency's spacecraft Planck, which mapped the CMB across the entire sky from 2009 until last year. However, the BICEP team apparently interpreted the map as showing only the galactic emissions. In reality, it may also contain the largely unpolarized hazy glow from other galaxies, which has the effect of making the galactic microwaves coming from any particular point of the sky look less thoroughly polarized than they actually are. So using the map to strip out the galactic foreground may actually leave some of that foreground in the data where it could produce a spurious signal, Falkowski explains.

Carbon, Avogadro's Constant and the Importance of the Number 12 | MIT Technology Review

Carbon, Avogadro's Constant and the Importance of the Number 12 | MIT Technology Review: He says that a practical solution is to choose a number that is divisible by 12 so that a whole number of carbon-12 atoms are equal to the mass of a gram, at least to a first approximation...

His idea is to define Avogadro’s constant in terms of a number of hexagonal sheets of graphite piled on top of each other to form a hexagonal prism...

He suggests that if this number—the number of layers and the number of atoms along each hexagonal edge—was equal to 51,150,060, then the total would be 602,214,158,510,196,804,982,800 atoms.

Square Kilometre Array will see sky bubbling with exploding stars

Square Kilometre Array will see sky bubbling with exploding stars: The catch is that a gamma-ray burst is not an explosion that we can see from all directions but is comprised of a very narrow, energetic jet, so we need to be looking down the barrel of the jet at the right time...

The radio afterglow should be visible from any direction though and for long periods of time, even if we missed the burst.

Cosmologists weigh cosmic filaments and voids

Cosmologists weigh cosmic filaments and voids: While galaxies and filaments have more mass than the average regions of the universe, voids have less mass than average. This unbalanced distribution causes matter to rapidly move away from voids and towards the concentrations of mass along the cosmic filaments that lie between them.

"This means that voids act like objects with an effectively negative mass," Clampitt said, "such that even light rays bend away from them. They act roughly like concave lenses, the opposite of big galaxies, which act like convex lenses..."

Their results show that voids are not as empty as they appear. Dark matter and other dim structures permeate all the way to the center of the voids.

How the U.S. Built the World’s Most Ridiculously Accurate Atomic Clock | Science | WIRED

How the U.S. Built the World’s Most Ridiculously Accurate Atomic Clock | Science | WIRED: Both NIST-F2 and the standard it replaces, NIST-F1, are known as cesium-based atomic fountain clocks...

The previous generation of atomic clock was already quite good at figuring out the length of a second but had a few small sources of error. NIST-F1 operates at room temperature and so the walls of the chamber in which the cesium atom ball is tossed heat up, emitting a small amount of radiation. This interferes with the atoms, causing them to shift ever so slightly in their energy levels. By cooling NIST-F2 with liquid nitrogen, the new timepiece reaches temperatures of – 316 degrees Fahrenheit, virtually eliminating this excess radiation and reducing the shifting 100-fold.

A bound on the natural width of the Higgs boson

A bound on the natural width of the Higgs boson: In the Standard Model, the Higgs boson is expected to be very narrow: its width is roughly 4 MeV, a good 30,000 times smaller than the central mass of approximately 125 GeV...

The width is usually determined from the distribution of masses observed. In this case, however, the expected width is much smaller than the experimental resolution of the mass measurement...

A quantitative analysis leads to an upper bound on the Higgs width of ~4 times that of the Standard Model value, approximately 17 MeV. This is a huge improvement, of a factor of 200 over the previous bound.

How To Build A Quantum Telescope — Medium

How To Build A Quantum Telescope — Medium: Her idea is to use the astrophysical photons to stimulate the production of an entangled pair, inside a telescope. The first of this pair then hits the detector, generating an image. But the other can be used to increase the information known about the first, thereby increasing the resolution and beating the diffraction limit.

RAMBO allows high-magnetic-field experiments on a tabletop

RAMBO allows high-magnetic-field experiments on a tabletop: "We can literally see the sample inside the magnet," Kono said. "We have direct optical access, whereas if you go to a national high magnetic field facility, you have a monster magnet, and you can only access the sample through a very long optical fiber. You cannot do any nonlinear or ultrafast optical spectroscopy...

Kono's group built the system to analyze very small, if not microscopic, samples. A sample plate sits on a long sapphire cylinder that passes through the coil's container and juts through one end of the magnet to place it directly in the center of the magnetic field.

The cylinder provides one direct window to the experiment; a port on the other side of the container looks directly down upon the sample. The coil is bathed in liquid nitrogen to keep it cool at around 80 kelvins (-315 degrees Fahrenheit). The sample temperature can be independently controlled from about 10 K to room temperature by adjusting the flow of liquid helium to the sapphire cylinder.

Hubble bubble may explain different measurements of expansion rate of the universe

Hubble bubble may explain different measurements of expansion rate of the universe:  One way to determine the Hubble constant... is based on measuring the cosmic microwave background radiation... can also be derived from the movement of galaxies near the Milky Way, movement largely due to the expansion of the universe. "When you compare the results from the two methods, there is a deviation of about 9 percent..."

...The bubble describes regions of the universe where the density of matter falls below the cosmic average. "Until now knowledge of our cosmic neighbourhood has been too imprecise to determine whether or not we are in such a bubble", continues Dr. Marra. "But let's just assume for a moment that our Milky Way is located in a Hubble Bubble. Matter outside the bubble would then attract nearby galaxies so strongly that they would move more quickly than average. In this case we would measure a higher Hubble constant that would apply to our cosmic neighbourhood, but not to the universe as a whole."

New Measurement of Gravitational Constant Comes Up Higher Than Expected - Wired Science

New Measurement of Gravitational Constant Comes Up Higher Than Expected - Wired Science: The team, led by Terry Quinn, the former director of the International Bureau of Weights and Measures in France, used an updated version of Cavendish’s setup for one experiment. But they conducted an additional experiment, using a servo to counteract the twisting of the wire and figuring out the gravitational constant based on the voltage required to keep their apparatus from moving. Taken together, their tests yielded a new G value of 6.67545 × 10−11 m3⁄kg s2, which is higher than the current accepted value by about 240 parts per million.