Ever since the late 19th century, physicists have known about a counterintuitive property of some electric circuits called negative resistance. Typically, increasing the voltage in a circuit causes the electric current to increase as well. But under some conditions, increasing the voltage can cause the current to decrease instead. This basically means that pushing harder on the electric charges actually slows them down
So… can we expect cheaper and better lenses?
Better? Yes. Truly sharper from corner to corner.
The problem is that the 60-to-90-foot-long friction piles underpinning the building were driven into sandy soils rather than bedrock at 200 feet down. While no concrete explanation has been given for continued sinkage, developer Millennium Partners has blamed construction of the neighboring Salesforce Tower for pumping out too much groundwater and causing the soil to settle.
The test involves a miniature elevator stand-in—a box just six centimetres (2.4 inches) long, three centimetres wide, and three centimetres high.
If all goes well, it will provide proof of concept by moving along a 10-metre cable suspended in space between two mini satellites that will keep it taut.
Rotor sails rely on a bit of aerodynamics known as the Magnus effect. In the 1850s, German physicist Heinrich Gustav Magnus noticed that when moving through air a spinning object such as a ball experiences a sideways force. The force comes about as follows. If the ball were not spinning, air would stream straight past it, creating a swirling wake that would stretch out directly behind the ball like the tail of a comet. The turning surface of a spinning ball, however, drags some air with it. The rotation deflects the wake so that it comes off the ball at an angle, closer to the side of the ball that’s rotating into the oncoming air. Thanks to Isaac Newton’s third law that every action must have an equal and opposite reaction, the deflected wake pushes the ball in the opposite direction, toward the side of the ball that’s turning away from the oncoming air. Thus, the spinning ball gets a sideways shove.
The conceptual problems arise with momentum. The system’s total momentum increases as it begins to move. But where does this momentum come from? Shawyer had no convincing explanation, and critics said this was an obvious violation of the law of conservation of momentum.
McCulloch says there is observational evidence for this in the form of the famous fly by anomalies. These are the strange jumps in momentum observed in some spacecraft as they fly past Earth toward other planets. That’s exactly what his theory predicts.
That faint rising tone, physicists say, is the first direct evidence of gravitational waves, the ripples in the fabric of space-time that Einstein predicted a century ago (Listen to it here.). And it is a ringing (pun intended) confirmation of the nature of black holes, the bottomless gravitational pits from which not even light can escape, which were the most foreboding (and unwelcome) part of his theory..
“Everything else in astronomy is like the eye,” he said, referring to the panoply of telescopes that have given stargazers access to more and more of the electromagnetic spectrum and the ability to peer deeper and deeper into space and time. “Finally, astronomy grew ears. We never had ears before.”
The scientists placed two diamonds on opposite sides of the Delft University campus, 1.3 kilometers apart.
Each diamond contained a tiny trap for single electrons, which have a magnetic property called a “spin.” Pulses of microwave and laser energy are then used to entangle and measure the “spin” of the electrons.
A potential weakness of the experiment, he suggested, is that an electronic system the researchers used to add randomness to their measurement may in fact be predetermined in some subtle way that is not easily detectable, meaning that the outcome might still be predetermined as Einstein believed.
For decades, metrologists have strived to retire ‘Le Grand K’ — the platinum and iridium cylinder that for 126 years has defined the kilogram from a high-security vault outside Paris. Now it looks as if they at last have the data needed to replace the cylinder with a definition based on mathematical constants.
If they are proved right, in 2018, Le Grand K will join the metre as a museum piece. “We’ll keep it,” says Davis, “but it won’t be defining anything anymore.”
Because these new magnets also have energy efficient characteristics, they can be used to create a new generation of sensors and actuators with vanishingly small heat signatures, said the researchers. These magnets could also find applications in efficient energy harvesting devices; compact micro-actuators for aerospace, automobile, biomedical, space and robotics applications; and ultra-low thermal signature actuators for sonars and defense applications.
Since these new magnets are composed of alloys that are free of rare-earth elements, they could replace existing rare-earth based magnetostriction alloys, which are expensive and feature inferior mechanical properties, said researchers.