New method for propulsion in fluids | MIT News Office

New method for propulsion in fluids | MIT News Office: The effect itself is surprisingly simple, Peacock explains: “By virtue of heating or cooling the surface of an object, you change the density of any fluid next to that surface.” In the valley winds previously considered, the object was either a glacier or a valley wall heated by the sun, and the fluid was the air passing over it; in this case, it’s the solid wedge and its surrounding water.
The changed density of the fluid generates a flow over the surface, Peacock says, adding, “That flow then creates unbalanced forces, with lower pressure on one side, and higher on the other” — an imbalance that propels the object from the higher pressure toward the lower.

Particles near absolute zero do not break the laws of physics after all

Particles near absolute zero do not break the laws of physics after all: The authors focused on a model system favored by thermodynamics experts that consists of a free particle strongly coupled to a heat bath, representing the effect of its environment... Previous theoretical predictions suggested that, under certain circumstances, the specific heat can decrease below zero at a temperature of strictly zero (−273.15°C)...

...In fact, a real particle will always be confined to a finite volume—even if that volume may be extremely large. Therefore, they discovered that previous studies need to be modified in order to account for a spatial confinement of the particle...

Quantum Entanglement Drives the Arrow of Time, Scientists Say | Simons Foundation

Quantum Entanglement Drives the Arrow of Time, Scientists Say | Simons Foundation: Using an obscure approach to quantum mechanics that treated units of information as its basic building blocks, Lloyd spent several years studying the evolution of particles in terms of shuffling 1s and 0s. He found that as the particles became increasingly entangled with one another, the information that originally described them (a “1” for clockwise spin and a “0” for counterclockwise, for example) would shift to describe the system of entangled particles as a whole. It was as though the particles gradually lost their individual autonomy and became pawns of the collective state. Eventually, the correlations contained all the information, and the individual particles contained none. At that point, Lloyd discovered, particles arrived at a state of equilibrium, and their states stopped changing, like coffee that has cooled to room temperature.

“What’s really going on is things are becoming more correlated with each other,” Lloyd recalls realizing. “The arrow of time is an arrow of increasing correlations.”

Material looks cool while heating up | Science News

Material looks cool while heating up | Science News:  The compound vanadium dioxide makes such a transition around 70o Celsius, switching abruptly from being an electrical insulator to a conductor...

... the researchers heated the vanadium dioxide-sapphire sample and, with an infrared camera, measured how much infrared light the sample emitted as it warmed. The color gradually shifted from blue to red as the sample's temperature increased from 60o to 74o, as is typical for a warming object. But then something strange happened: Even though the sample’s temperature continued to rise up to 100o, the camera readout returned to an icy blue and stayed there.

IBM unveils concept for a future brain-inspired 3D computer | KurzweilAI

IBM unveils concept for a future brain-inspired 3D computer | KurzweilAI: IBM has unveiled a prototype of a new brain-inspired computer powered by what it calls “electronic blood,” BBC News reports.

The firm says it is learning from nature by building computers fueled and cooled by a liquid, like our minds...

Its new “redox flow” system pumps an electrolyte “blood” through a computer, carrying power in and taking heat out.

'Black holes' of the ocean could curb climate change - environment - 26 September 2013 - New Scientist

'Black holes' of the ocean could curb climate change - environment - 26 September 2013 - New Scientist: Swirling masses of water in the ocean are mathematically the same as the warped regions of space-time around cosmic singularities...

In this so-called photon sphere, light is trapped in loops that spin around the black hole forever.


"The boundaries of water-carrying eddies satisfy the same type of differential equations that the area surrounding black holes do in general relativity..."

Fastest rotating man-made object created

Fastest rotating man-made object created: To do this they manufactured a microscopic sphere of calcium carbonate only 4 millionths of a metre in diameter. The team then used the miniscule forces of laser light to hold the sphere with the radiation pressure of light...
They exploited the property of polarisation of the laser light that changed as the light passed through the levitating sphere, exerting a small twist or torque.
Placing the sphere in vacuum largely removed the drag (friction) due to any gas environment, allowing the team to achieve the very high rotation rates...

"I am intrigued with the prospect of extending this to multiple trapped particles and rotating systems. We may even be able to shed light on the area of quantum friction – that is – does quantum mechanics put the brakes on the motion or spinning particle even though we are in a near perfect vacuum with no other apparent sources of friction?"

The first electrically powered nanolasers capable of being operated at room temperature

The first electrically powered nanolasers capable of being operated at room temperature: Dr. Ning's latest approach employed the same indium phosphide/indium gallium arsenide/indium phosphide (InP/InGaAs/InP) rectangular core and the same silicon nitride (SiN) insulating layer—encapsulated in a silver shell—used in a previous mockup, which failed due to overheating. When the team refined the fabrication process and adjusted the thickness of the SiN layer, the heat dissipated at a much faster rate—enough to keep the nanolaser in continuous operation.
In an ASU press release, Dr. Ning noted that, "In terms of fundamental science, it shows for the first time that metal heating loss is not an insurmountable barrier for room-temperature operation of a metallic cavity nanolaser under electrical injection; for a long time, many doubted if such operation is even possible at all."

Most accurate measurement of Boltzmann constant yet

Most accurate measurement of Boltzmann constant yet: In this study, the researchers... used acoustic thermometry to make the measurement by building an acoustic resonator and making amazingly precise measurements of the speed of sound in argon gas.
The researchers first cooled the resonator to the temperature of the triple point of water so they knew the temperature exactly in the current definition and filled it with argon gas...
Then they used the speed of sound measurement to calculate the average speed of the argon molecules and hence the average amount of kinetic energy that they had – from this they were able to calculate the Boltzmann constant with an extremely high accuracy.

Physicists build quantum refrigerator based on four quantum dots

Physicists build quantum refrigerator based on four quantum dots: The proposed system consists of four quantum arranged in a square configuration, which the researchers call a "quadridot." The scientists theoretically showed that this quadridot acts as a quantum refrigerator when coupled to four independent reservoirs (one hot, one cold, and two of intermediate temperature). The quadridot pumps energy in the form of electrons from the hot reservoir and the cold reservoir to the intermediate-temperature reservoirs. When properly tuned, the quadridot can cool the quantum dot in contact with the cold reservoir to a temperature that is lower than its original temperature.
This configuration overcomes one of the biggest difficulties in realizing self-contained quantum refrigerators, which is engineering the interaction among the hot-, cold-, and intermediate-temperature reservoirs. The quantum dot array provides a relatively simple way to achieve this three-body interaction that may be possible to experimentally realize in the future.

Ultimate chill: The epic race to reach absolute zero

Ultimate chill: The epic race to reach absolute zero
http://www.newscientist.com/article/mg21829222.100-ultimate-chill-the-epic-race-to-reach-absolute-zero.html?cmpid=RSS%7CNSNS%7C2012-GLOBAL%7Conline-news&utm_source=feedly


We can also use the incomparably pure quantum-dominated environments of ultra-cold materials to model extreme conditions in the interior of a neutron star, fundamental particle interactions, and phase transitions in the earliest moments of the universe. At low temperatures, electrons interact to create fundamental excitations – sometimes called quasiparticles – with a mass up to a thousand times that of a free electron, much as fundamental particles in free space acquire mass by interaction with the Higgs field. Similarly, quasiparticle excitations in superconductors have recently been shown to behave like Majorana particles, long-predicted objects that are their own antiparticles.

Cells as living calculators - MIT News Office

Cells as living calculators - MIT News Office: MIT engineers have transformed bacterial cells into living calculators that can compute logarithms, divide, and take square roots, using three or fewer genetic parts.

Inspired by how analog electronic circuits function, the researchers created synthetic computation circuits by combining existing genetic “parts,” or engineered genes, in novel ways...


To create an analog adding or multiplying circuit that can calculate the total quantity of two or more compounds in a cell, the researchers combined two circuits, each of which responds to a different input. In one circuit, a sugar called arabinose turns on a transcription factor that activates the gene that codes for green fluorescent protein (GFP). In the second, a signaling molecule known as AHL also turns on a gene that produces GFP. By measuring the total amount of GFP, the total amount of both inputs can be calculated.

To subtract or divide, the researchers swapped one of the activator transcription factors with a repressor, which turns off production of GFP when the input molecule is present. The team also built an analog square root circuit that requires just two parts, while a recently reported digital synthetic circuit for performing square roots had more than 100.

Superfluids: Observation of 'second sound' in a quantum gas

Superfluids: Observation of 'second sound' in a quantum gas: ...fluids in this state conduct heat extremely efficiently, with energy transport occurring in a distinct temperature wave. Because of the similarities to a sound wave, this temperature wave is also called second sound...


In the laboratory, Grimm's team of quantum physicists prepared a quantum gas consisting of about 300,000 lithium atoms. They heated the cigar-shaped particle cloud locally with a power-modulated laser beam and then observed the propagating temperature wave. "While in superfluid helium only one entropy wave is generated, our Fermi gas also exhibited some thermal expansion and, thus, a measurable density wave," explains Grimm the crucial difference.

nsf.gov - National Science Foundation (NSF) Discoveries - Energy Efficient Brain Simulator Outperforms Supercomputers - US National Science Foundation (NSF)

nsf.gov - National Science Foundation (NSF) Discoveries - Energy Efficient Brain Simulator Outperforms Supercomputers - US National Science Foundation (NSF): Each of Neurogrid's 16 chips contains more than 65,000 silicon "neurons" whose activity can be programmed according to nearly 80 parameters, allowing the researchers to replicate the unique characteristics of different types of neurons. Soft-wired "synapses" crisscross the board, shuttling signals between every simulated neuron and the thousands of neurons it is networked with, effectively replicating the electrical chatter that constitutes communication in the brain.

Quantum gas goes below absolute zero : Nature News & Comment

Quantum gas goes below absolute zero : Nature News: Normally, most particles have average or near-average energies, with only a few particles zipping around at higher energies. In theory, if the situation is reversed, with more particles having higher, rather than lower, energies, the plot would flip over and the sign of the temperature would change from a positive to a negative absolute temperature...
Schneider and his colleagues reached such sub-absolute-zero temperatures with an ultracold quantum gas made up of potassium atoms. Using lasers and magnetic fields, they kept the individual atoms in a lattice arrangement. At positive temperatures, the atoms repel, making the configuration stable. The team then quickly adjusted the magnetic fields, causing the atoms to attract rather than repel each other. “This suddenly shifts the atoms from their most stable, lowest-energy state to the highest possible energy state, before they can react,” says Schneider.

Entanglement Makes Quantum Batteries Almost Perfect, Say Theorists | MIT Technology Review

Entanglement Makes Quantum Batteries Almost Perfect, Say Theorists | MIT Technology Review: Alicki and Fannes show that when quantum batteries are entangled they become much better. That’s essentially because all the energy from all the batteries can be extracted at once...
In fact, as the number of entangled batteries increases, the performance becomes arbitrarily close to the thermodynamic limit...
...Quantum batteries in the form of atoms or molecules may be ubiquitous in nature, in processes such as photosynthesis. Biologists know for example that during photosynthesis, energy is transferred with 100 per cent efficiency from one molecular machine to another.
How this happens, nobody knows.

Illinois Group’s Fusion Reactor Innovation Experiment Proves Successful in China

Illinois Group’s Fusion Reactor Innovation Experiment Proves Successful in China: Ruzic and his students in the Center for Plasma Material Interactions (CPMI) designed a method for molten lithium to self-circulate along the surface of a fusion reactor’s diverter, where excess heat is collected and removed. Such an innovation, Ruzic believes, could reduce the size of a fusion reactor’s radius by a third, while allowing it to produce the same volume of energy.

 “We’re looking at a factor of 10 in cost reductions, at least,” Ruzic said.

The concept, known as LiMIT (Lithium/Metal Infused Trenches), previously was successfully conducted in CPMI laboratories. Ruzic believes the success in China shows that LiMit works on an actual fusion device as well as in the laboratory.

The surprise theory of everything

The surprise theory of everything: The question is whether we can express the whole of physics simply by enumerating possible and impossible processes in a given situation. This is very different from how physics is usually phrased, in both the classical and quantum regimes, in terms of states of systems and equations that describe how those states change in time. The blind alleys down which the standard approach can lead are easiest to understand in classical physics, where the dynamical equations we derive allow a whole host of processes that patently do not occur - the ones we have to conjure up the laws of thermodynamics expressly to forbid, such as dye molecules reclumping spontaneously in water...

Apply this logic more generally, and time ceases to exist as an independent, fundamental entity, but one whose flow is determined purely in terms of allowed and disallowed processes. With it go problems such as that I alluded to earlier, of why the universe started in a state of low entropy. If states and their dynamical evolution over time cease to be the question, then anything that does not break any transformational rules becomes a valid answer.

The real reason why the Pioneer spacecrafts appear to be slowing down

The real reason why the Pioneer spacecrafts appear to be slowing down: According to Sergei Kopeikin, the previous explanation for the so-called Pioneer anomaly was only able to account for 15 to 20% of the observed deceleration. Kopeikin, on the other hand, devised a new set of calculations which factored in the expansion of the universe — including the way it affects the movement of photons that make up light and radio waves.

Physicist Derives Laws of Thermodynamics For Life Itself

Physicist Derives Laws of Thermodynamics For Life Itself:  His idea is to examine every combination of states that are possible in this box and to consult an omniscient microbiologist about whether each state represents a bacterium or not. In that way, it ought to be possible, at least in principle, to gain an idea of the statistical physics involved.

Next, he asks the microbiologist to take another look at the box after a period that is roughly equivalent to the time it takes for bacteria to divide...

This sets an important bound on what is thermodynamically possible in this system: in effect, England derives the second law of thermodynamics for the system...