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.

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.

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...

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...

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.

A Tractor Beam Made Of Sound Waves | Popular Science

A Tractor Beam Made Of Sound Waves | Popular Science: The device consists of about a thousand ultrasound emitters, placed underwater. When turned on, scientists used it to tug along centimeter-sized objects (roughly half and inch), such as a small hollow triangular shape. Normally the effect of sending acoustic beams at something would tend to push it away. But the scientists found that by precisely controlling the angle of sound waves, they can create a low pressure zone in front of the object, thus pulling it closer.

Turning Pull Into Push? - ScienceNOW

Turning Pull Into Push? - ScienceNOW: To see how this scenario works, consider the case in which just a point charge moves across the surface of an insulator. In that case, the polarization pattern moves with it, becoming so-called evanescent waves that still attract the point charge.

If the point charge moves fast enough, another factor comes into play. In an insulating material such as glass, light travels slower than in empty space. And if a charge moves through the glass faster than light can, it creates a shockwave of light, known as Cherenkov radiation, much like the sonic boom from a supersonic jet. Now, if a point charge above the insulator whizzes along faster than light can within the material, then the induced polarization pattern will move that fast as well and create Cherenkov radiation. That radiation flows at an angle down into the material and carries momentum with it. But by Newton's law that every action has an equal and opposite reaction, the downward flow of momentum must be balanced by an upward push on the point charge.

Tractor beam built from rings of laser light - New Scientist - New Scientist

Tractor beam built from rings of laser light: David Ruffner and David Grier of New York University instead projected two Bessel beams side by side and used a lens to angle them so that they overlapped, creating a pattern of alternating bright and dark regions along the length of the beam. Fine-tuning the beam causes photons in the bright regions, initially flowing past a chosen particle in the beam, to scatter backwards. When these photons hit the particle, they knock it to the next bright region. The particle is thus constantly pushed close to the beam's source.

'Crowd Quakes' Were A Key Factor In LoveParade Disaster

'Crowd Quakes' Were A Key Factor In LoveParade Disaster: Helbing and Mukerjee say most deaths occurred elsewhere in the crowd because of a phenomenon known as crowd quakes. These occur when the density of a crowd becomes so great that individuals are forced into bodily contact with each other.
When this happens, the forces are transmitted through the crowd in chains  from one body to the next. Crucially, when this happens, the transmitted forces add up...
And this is what kills: not the overall density of the crowd but the transmission of lethal force through the crowd in ways that are almost random. This causes people to fall, creating a domino effect that crushes people to death.

Bessel beam "tractor beam" concept theoretically demonstrated

Bessel beam "tractor beam" concept theoretically demonstrated: Haifeng Wang at the A*STAR Data Storage Institute and colleagues studied the properties of Bessel beams, which, unlike normal laser beams, don’t diffract or spread out as they propagate. While light will usually be scattered backwards when a laser beam hits a small particle in its path, pushing the particle forward, the A*STAR team showed theoretically that light from a Bessel beam scatters off particles that are sufficiently small in a forward direction...
While true Bessel beams are impossible to create, as they would require an infinite amount of energy, reasonably good approximations can be made and are used in many optical applications.

Blog - Giant Casimir Effect Predicted Inside Metamaterials

Blog - Giant Casimir Effect Predicted Inside Metamaterials:  They say that in a particular kind of electromagnetic space called a Rindler space, the Casimir effect is huge. The essential idea here is that the space can be designed to allow only certain wavelengths to operate. If the electromagnetic properties of the Rindler space are matched to the ambient temperature, then these kinds of thermal waves can be made to dominate the Casimir energy.

That makes the Casimir energy huge. Zhao and Miao calculate that in a lab at 300K (room temperature), the Casimir energy would be some 10^11 times bigger than the free space value...

Zhao and Miao also say that this kind of material ought to be relatively straightforward to build, layer by layer.

Not Pulling Your Leg: Tractor Beams May Be Possible

Not Pulling Your Leg: Tractor Beams May Be Possible: The tractor beam would work in a new way. In this case, the light would pull an object toward the source of the beam even though the beam has the same intensity all along its length. The trick is to use a special type of laser beam. In an ordinary beam, each photon moves in the direction of the beam, so when a photon bounces directly back from an object, it imparts the largest possible push. However, physicists can generate a beam by overlapping light waves that make an angle relative to the desired direction (see figure). The overlapping waves produce a forward-moving beam known as a Bessel beam whose intensity remains constant along its length. But each photon is now moving at an angle relative to the beam. So when one bounces off an object, it exerts a smaller forward push.

Nevertheless, the beam is still pushing, and to overcome that push, physicists need to rely on another bit of physics. Again, the light will polarize the material in the object electrically and magnetically. The polarized object will then radiate and redirect the light. By adjusting the material properties of the object and the polarizations and synchronization of the individual light waves in the beam, physicists can make the object radiate more light forward along the beam than backward toward its source. The radiated light then acts like a reverse thruster, overcoming the already-reduced forward push of the beam and driving the object back toward its source.

Experiments Show Gravity Is Not an Emergent Phenomenon� - Technology Review

Experiments Show Gravity Is Not an Emergent Phenomenon� - Technology Review:  Kobakhidze argues that since each quantum particle must be described by a large number of other particles, this leads to a particular equation that describes the effect of gravity.

But here's the thing: the conventional view of gravity leads to a different equation...

As it happens, physicists have been measuring the force of gravity on neutrons for ten yeas or so. And...wait for the drum roll... the results exactly match the predictions of traditional gravitational theory, says Kobakhidze.

Mystery signal at Fermilab hints at 'technicolour' force - physics-math - 07 April 2011 - New Scientist

Mystery signal at Fermilab hints at 'technicolour' force : Just over 20 years ago, Lane, along with Fermilab physicist Estia Eichten, predicted that experiments would see just such a signal. Lane and Eichten were working on a theory known as technicolour, which proposes the existence of a fifth fundamental force in addition to the four already known: gravity, electromagnetism, and the strong and weak nuclear forces. Technicolour is very similar to the strong force, which binds quarks together in the nuclei of atoms, only it operates at much higher energies. It is also able to give particles their mass – rendering the Higgs boson unnecessary.

The new force comes with a zoo of new particles. Lane and Eichten's model predicted that a technicolour particle called a technirho would often decay into a W boson and another particle called a technipion.

In a new paper, Lane, Eichten and Fermilab physicist Adam Martin suggest that a technipion with a mass of about 160 GeV could be the mysterious particle producing the two jets. "If this is real, I think people will give up on the idea of looking for the Higgs and begin exploring this rich world of new particles," Lane says.

How To Turn A Laser Into A Tractor Beam - Technology Review

How To Turn A Laser Into A Tractor Beam - Technology Review: Jun Chen from Fudan University in China and a few pals demonstrate the counterintuitive result that photons can pull things too. In other words, they've worked out how to generate a backward pulling force from a forward propagating beam.

Chen and buddies say this is possible when the system meets two conditions. First, it works only for beams in which the momentum in the direction of propagation is small, as is the case for beams that merely glance off an object. Second, the photons must simultaneously excite several multipoles within the particle, which scatter the beam.

If the scattering angle is just right, the total momentum in the direction of propagation can be negative, meaning the particle is pulled back towards the source and the light becomes a tractor beam.

Casimir effect put to work as a nano-switch - New Scientist - New Scientist

Casimir effect put to work as a nano-switch - New Scientist - New Scientist - "A new technique that takes control of the Casimir effect – a strange quantum phenomenon that gums up nanoelectromechanical systems (NEMS) – may pave the way to a switch that could cut the power consumption of nanoscale gadgets."

A Blueprint for a Quantum Propulsion Machine | MIT Technology Review

A Blueprint for a Quantum Propulsion Machine | MIT Technology Review: ...the quantum vacuum constantly interacts with magnetoelectric materials generating Lorentz forces. Most of the time, however, these forces sum to zero.

However, Feigel says there are four cases in which the forces do not sum to zero...

The first method is to rapidly aggregate a number of magnetoelectric nanoparticles, a process which influences the boundary conditions for higher frequency electromagnetic waves, generating a force.

The second is simply to rotate a group of magnetoelectric nanoparticles, which also generates a Lorentz force.

Either way, the result is a change in velocity. As Feigel puts it: “mechanical action of quantum vacuum on magneto-electric objects may be observable and have a significant value.”

The beauty of Feigel’s idea is that it can be easily tested. He suggests building an addressable array of magnetoelectric nanoparticles, perhaps made of a material such as FeGaO3 which has a magnetoelectric constant of 10^-4 in a weak magnetic field.