Unmanned aerial vehicles beware: We’ve got laser weapons.

This week defense contractor Raytheon debuted video of a test conducted with the U.S. Navy in California this May, in which the company’s laser weapon shot down four UAVs. The shaky black-and-white footage shows lasers locked on an aircraft until it loses control and plunges into the sea.

The Navy’s laser depends upon a guidance system it already uses on its ships—Raytheon’s Phalanx Close-In Weapon System, which normally uses radar to guide a 20mm Gatling gun.

Raytheon developed the system after buying six off-the-shelf commercial lasers from the car industry and joining them to make a single, powerful beam guided by the Phalanx’s radars. Unlike other tests which have been conducted on aircraft it uses a solid state laser rather than a chemical generated beam [The Telegraph].

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It wasn’t supposed to be like this. The Higgs boson, dark matter, neutrinos—weird or poorly understood phenomena like these seemed the likely candidates to provide a surprise that changes particle physics. Not an old standby like the proton.

But the big story this week in Nature is that we might have been wrong all along in estimating something very basic about the humble proton: its size. A team from the Paul-Scherrer Institute in Switzerland that’s been tackling this for a decade says its arduous measurements of the proton show it is 4 percent smaller than the previous best estimate. For something as simple as the size of a proton, one of the basic measurements upon with the standard model of particle physics is built, 4 percent is a vast expanse that could shake up quantum electrodynamics if it’s true.

If the [standard model] turns out to be wrong, “it would be quite revolutionary. It would mean that we know a lot less than we thought we knew,” said physicist Peter J. Mohr of the National Institute of Standards and Technology in Gaithersburg, Md., who was not involved in the research. “If it is a fundamental problem, we don’t know what the consequences are yet” [Los Angeles Times].

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A team of scientists led by Mark Raizen at the University of Texas at Austin had the gumption to take on Einstein. And according to their new paper in Science, they won. The point of contention? The lovechild of statistical mechanics and thermodynamics: Brownian motion.

Here’s how they did it.

Step 1. Learning the Moves

In the 1820s, Scottish botanist Robert Brown looked through a microscope at plant bits floating in water, and wrote [PDF]:

“I observed many of them very evidently in motion . . . [these motions] arose neither from currents in the fluid, nor from its gradual evaporation, but belonged to the particle itself.”

To make sure that the pollen wasn’t alive–actually swimming around–Brown tried it with coal dust. Dust had the same moves.

Today, we understand that Brownian motion, the random break dance of these tiny particles, comes from the water molecules bumping against them. In 1905, Einstein determined the properties of the liquid and the particles that would help describe their wanderings and the motion of molecules. But he also said that it was “impossible” to determine at any moment the speed and direction of a single particle during this dance.

Step 2. Water Into Air

The reason for Einstein’s doubt? The particles bumped around too quickly to ever measure their speed and direction:

He believed that it would be impossible in practice to track this motion, given the incredibly short timescales over which the Brownian fluctuations take place. [PhysicsWorld]

How quick is too quick? A very tiny glass sphere (think micrometers) in water would change direction almost every 100 nanoseconds (about the time it takes light to travel 30 meters). Raizen wanted to make the time between moves longer, so they didn’t use water. They put the glass beads on a dance floor with fewer partners, using a medium whose molecules are farther apart: air.

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Sometimes you have to change your vantage point to really see something.

The New York Times today reports on the work of Diane and Arlen Chase, who spent more than 20 years cutting through the Central American jungle to survey the Ancient Mayan city of Caracol in present-day Belize. But when they were turned on to the possibility of using flyover missions equipped with laser technology that could see to the jungle floor, their research accelerated dramatically.

In only four days, a twin-engine aircraft equipped with an advanced version of lidar (light detection and ranging) flew back and forth over the jungle and collected data surpassing the results of two and a half decades of on-the-ground mapping, the archaeologists said. After three weeks of laboratory processing, the almost 10 hours of laser measurements showed topographic detail over an area of 80 square miles, notably settlement patterns of grand architecture and modest house mounds, roadways and agricultural terraces [The New York Times].

Given such dramatic results, you might think the scientists would have started working from above earlier. After all, learning by bouncing lasers around isn’t new: Satellites have measured the Antarctic ice by reflecting lasers of the sheet and back into space, then measuring how long it took. Scientists have bounced lasers off reflectors that U.S. and Russian moon missions left behind, measuring the moon’s slow progression away from the Earth.

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The rainmakers of the 21st century may be armed with powerful lasers. New research suggests that zapping clouds with laser beams could trigger the formation of condensation droplets that would fall to the ground as rain. But while the study, published in Nature Photonics, raises the tantalizing hope of bringing on-demand rain to parched regions, some experts argue the technique is unlikely to ever be practical.

For more than 50 years, efforts to try to artificially induce rain have concentrated on ‘cloud seeding’ — scattering small particles of silver iodide into the air to act as ‘condensation nuclei’, or centres around which rain droplets can grow. “The problem is, it’s still not clear that cloud seeding works efficiently,” says optical physicist Jérôme Kasparian at the University of Geneva, Switzerland. “There are also worries about how safe adding silver iodide particles into the air is for the environment” [Nature News].

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Four decades ago, the Soviet Union put a reflector on the moon able to bounce laser signals back to the Earth. There was just one problem: They lost it.

But now the marooned reflector has been found, thanks to the determined hunting of University of California, San Diego researchers. NASA’s Lunar Reconnaissance Orbiter, in orbit around the moon, photographed the landing area where the USSR’s Luna 17 mission dropped off the missing reflector, Lunokhod 1, in 1970. The photos turned up a faint reflective dot, and the team thought that was it.

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It sounded like a good idea at the time: You’d had one too many at the pub, one thing led to another, and you ended with someone’s name tattooed on your back. When you rushed out as soon as possible for laser removal of the unfortunate ink, the practitioners were actually using the same techniques that some art restorers employ to remove dirt and grime from masterpieces. And according to a new study in the journal of the American Chemical Society, Accounts of Chemical Research, laser ablation is getting better and more widespread in the art world.

Salvatore Siano at the Applied Physics Institute-CNR in Florence, Italy, tried out the method on a few classic works of art to record the results scientifically. He cleaned parts of a wall painting from a church in Siena, Italy, and also worked on Lorenzo Ghiberti’s gilded bronze panels Porta del Paradiso, or Gate of Paradise, and Donatello’s Renaissance bronze statue of David [BBC News]. While others have experimented like this over the last decade, he says, the Gates of Paradise was the first widely recognized masterwork to receive the treatment. He also notes that treating paintings poses the greatest challenge, but says that the laser cleaning showed great results–in the image above, the angel on the right was cleaned with laser ablation, while the two angels on the left received traditional cleaning.

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Success! The video below shows a test the military ran off the California coast last week, in which a modified Boeing 747 carrying a laser used it to shoot down a test missile; it was the first time a laser weapon has destroyed a missile in its booster stage. DISCOVER covered the first flight tests of this system back in 2008.

The liquid-fueled rocket – thought to be a Scud-B, similar to those being developed by Iran and North Korea – was fired from a ship off the coast California on 11 February [New Scientist]. The plane locked in its tracking lasers, and then unleashed a chemical laser that burned a hole in the side of the missile to blow it up. The Missile Defense Agency ran three total tests, two of which were successful.

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The hunt for fusion energy is one that has been plagued by false starts and overly-optimistic announcements. This week, however, researchers at the National Ignition Facility in California announced a major new step: firing all of its 192 lasers together for the first time, and channeling the beam into an area no bigger than a pencil eraser.

That tiny target is called the hohlraum. It’s a gold-plated cylinder intended to contain the hydrogen isotopes deuterium and tritium, which would fuse together during a potential fusion reaction. In this test, documented in the journal Science this week, the 192 lasers heated up the hohlraum to “only” about 6 million degrees Fahrenheit. But, team member Jeffrey Atherton says, the NIF is working its way up to the really powerful reactions. “The point is that we were doing it at a scale that’s about 20 times larger than has been done, with a laser power that accordingly is about 20 times higher than has been done, with a precision and efficiency that hasn’t been done before,” he said [MSNBC].

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Scientists have figured out a way to switch brain cells on and off like light bulbs, but instead of using a clapper, they’re using microbial proteins and lasers. Ed Boyden, a neuroscientist at the Massachusetts Institute of Technology, has developed a way to shut down parts of a brain just by shining light on them. When the light is turned off, the brain switches back on [Forbes].

The research team says their technology will help neuroscientists probe the brain’s circuitry by silencing certain regions and studying the effects. The technique, which was described in the journal Nature, could one day be used to shut down overactive regions of the brain often found in people with epilepsy, depression, Parkinson’s disease, and blindness.

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There’s nothing like the round number at the start of a new decade to get everyone prognosticating (yes, we know some of you are in the crowd that says the new decade doesn’t begin until 2011; OK, fine). To predict what the scientific scene will be like in 2020, the journal Nature brought in experts from 18 fields. Though the collection doesn’t encapsulate the “world of tomorrow” feel of, say, the old Omni magazine, it’s still packed with sunny (and scary) forecasts. Some show lingering uncertainty, some unbridled optimism, and some give warnings to the world to make a much-needed course correction. Here are five we thought were particularly telling.

1. In 2020, Google defines your reality (even more than it does already).

Peter Norvig, Google’s director of research, tackles the question of where search will be a decade hence. Advanced, he says, but also troublesome: Most searches will be spoken rather than typed, and designers will be experimenting with search systems that read your brain waves. “Users will decide how much of their lives they want to share with search engines, and in what ways”—such is Norvig’s polite description of a world with even less digital privacy than today’s.

What search engines give you back will change, too. Particularly, he says, they will come up with a way to judge relevance and quality that doesn’t rely on popularity: “Thus, a site that claims that the Moon landings were a hoax and seems to have a coherent argument structure will be judged to be lower quality than a legitimate astronomy site, because the premises of the hoax argument are at odds with reality.”

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A laser-powered robot took a climb up a cable in the Mohave Desert in Wednesday, and pushed ahead the sci-fi inspired notion of a space elevator capable of lifting astronauts, cargo, and even tourists up into orbit. The robot, built by LaserMotive of Seattle, whizzed up 2,953 feet (nearly 1 kilometer) in about four minutes, which qualifies the team for at least $900,000 of the $2 million in prizes offered in the NASA-backed Space Elevator Games.

Theorized in the 1960s and then popularized by Arthur C. Clarke’s 1979 novel “The Fountains of Paradise,” space elevators are envisioned as a way to gain access to space without the risk and expense of rockets. Instead, electrically powered vehicles would run up and down a cable anchored to a ground structure and extending thousands of miles up to a mass in geosynchronous orbit — the kind of orbit communications satellites are placed in to stay over a fixed spot on the Earth [AP].

The LaserMotive vehicle that climbed up the cable (held by a hovering helicopter) was powered by a system that resembles an upside-down solar power mechanism. Laser beams on the ground were fired up at the ascending craft and hit its photovoltaic cells–like those used in solar panels–in a process known as “power beaming.” LaserMotive will have a chance to improve its vehicle’s speed at another trial today, and other teams will also be vying for prizes.

Related Content:
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Image: Space Elevator Games. The LaserMotive vehicle gets weighed in.

It sounds like a scene from an insect version of Total Recall: Using genetically engineered fruit flies and laser beams, researchers have found a way to embed false, fearful memories in the flies.

Researchers first tested normal flies in a chamber where a jets of air on either side brought two different odors into the container. The researchers delivered an electric shock each time a fly strayed into a particular odour stream, which taught the flies to prefer the other one: the flies learned to move in the direction of the shock-related odour 30 per cent less often [New Scientist].

Next, the researchers created a strain of genetically engineered flies with certain neurons that would be activated by a laser blast. Lead researcher Gero Miesenböck explains that with this technique, called optogenetics, researchers can use light to activate particular cell types that have been genetically engineered to express a light-responsive protein. When laser pulses hit the brain, cells expressing the light-sensitive protein activate. “It’s like sending a radio signal to a city but only those houses with a radios set to the right frequency will get the signal,” says Miesenböck [Nature News].

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Nissan is looking to schools of fish to learn about how to help people reduce car crashes and traffic jams. The car company developed tiny robots that move in fish-like groups of up to 7 without bumping into each other. Each uses a laser range-finder to measure the distance between obstacles. The data is constantly shared between peers via radio, allowing the group to travel as a “shoal” without bumping into each other. The technique allows the cars to travel side-by-side or quickly switch direction as a group [BBC News]. The robot is dubbed Eporo, which stands for Episode O (Zero) Robot, meaning zero episodes, or accidents, and zero emissions.

This is Nissan’s second attempt at designing a crash avoidance system based on animal behavior. Their last attempt was the BR23C robot, modeled after the anti-collision behavior of bumblebees (check out a video of the bee based bot here). The Eporo, however, imitates three rules of fish movement: avoiding crashes, traveling side by side, and keeping close to other members of the school [CNET]. Nissan plans to unveil the Eporo at the Ceatec conference in Tokyo on October 6. 

Related Content:
80beats: Robo-Fish Are Ready to Take to the Seas
80beats: To Win the Evolutionary Race, Robots Learn to Deceive
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Image: Nissan

In future military operations, aircraft and submarines may be able to stay in contact by firing up the laser comm. Researchers have devised a new way to communicate with submarines by using high-energy laser beams to create bubbles of steam in the water, which then pop in little explosions that generate a 220-decibel pulse of sound. By controlling the frequency of explosions, researchers could make a kind of underwater Morse code.

According to a press release from the U.S. Naval Research Laboratory, one of the peculiar effects of high-intensity laser beams is that they can actually focus themselves when passing through some materials, like water. As the laser focuses, it rips electrons off water molecules, which then become superheated and create a powerful “pop”. Because different colours of light travel at markedly different speeds underwater, the precise location where different colours focus together could be manipulated by the suitable design of a many-coloured input pulse [BBC News].

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