Einstein was wrong about at least one thing: There are, in fact, "spooky actions at a distance," as now proven by researchers at the National Institute of Standards and Technology (NIST).
Einstein used that term to refer to quantum mechanics, which describes the curious behavior of the smallest particles of matter and light. He was referring, specifically, to entanglement, the idea that two physically separated particles can have correlated properties, with values that are uncertain until they are measured. Einstein was dubious, and until now, researchers have been unable to support it with near-total confidence.
As described in a paper posted online and submitted to Physical Review Letters (PRL), researchers from NIST and several other institutions created pairs of identical light particles, or photons, and sent them to two different locations to be measured. Researchers showed the measured results not only were correlated, but also—by eliminating all other known options—that these correlations cannot be caused by the locally controlled, "realistic" universe Einstein thought we lived in. This implies a different explanation such as entanglement.
The NIST experiments are called Bell tests, so named because in 1964 Irish physicist John Bell showed there are limits to measurement correlations that can be ascribed to local, pre-existing (i.e. realistic) conditions. Additional correlations beyond those limits would require either sending signals faster than the speed of light, which scientists consider impossible, or another mechanism, such as quantum entanglement.
The NIST results are more definitive than those reported recently by researchers at Delft University of Technology in the Netherlands.
In the NIST experiment, the photon source and the two detectors were located in three different, widely separated rooms on the same floor in a large laboratory building. The two detectors are 184 meters apart, and 126 and 132 meters, respectively, from the photon source.
The source creates a stream of photon pairs through a common process in which a laser beam stimulates a special type of crystal. This process is generally presumed to create pairs of photons that are entangled, so that the photons' polarizations are highly correlated with one another. Polarization refers to the specific orientation of the photon, like vertical or horizontal (polarizing sunglasses preferentially block horizontally polarized light), analogous to the two sides of a coin.
Photon pairs are then separated and sent by fiber-optic cable to separate detectors in the distant rooms. While the photons are in flight, a random number generator picks one of two polarization settings for each polarization analyzer. If the photon matched the analyzer setting, then it was detected more than 90 percent of the time.
In the best experimental run, both detectors simultaneously identified photons a total of 6,378 times over a period of 30 minutes. Other outcomes (such as just one detector firing) accounted for only 5,749 of the 12,127 total relevant events. Researchers calculated that the maximum chance of local realism producing these results is just 0.0000000059, or about 1 in 170 million. This outcome exceeds the particle physics community's requirement for a "5 sigma" result needed to declare something a discovery. The results strongly rule out local realistic theories, suggesting that the quantum mechanical explanation of entanglement is indeed the correct explanation.
The NIST experiment closed the three major loopholes as follows:
Fair sampling: Thanks to NIST's single-photon detectors, the experiment was efficient enough to ensure that the detected photons and measurement results were representative of the actual totals. The detectors, made of superconducting nanowires, were 90 percent efficient, and total system efficiency was about 75 percent.
No faster-than-light communication: The two detectors measured photons from the same pair a few hundreds of nanoseconds apart, finishing more than 40 nanoseconds before any light-speed communication could take place between the detectors. Information traveling at the speed of light would require 617 nanoseconds to travel between the detectors.
Freedom of choice: Detector settings were chosen by random number generators operating outside the light cone (i.e., possible influence) of the photon source, and thus, were free from manipulation. In fact, the experiment demonstrated a "Bell violation machine" that NIST eventually plans to use to certify randomness.
Astronomers have spotted a strange mess of objects whirling around a distant star. Scientists who search for extraterrestrial civilizations are scrambling to get a closer look.
In the Northern hemisphere’s sky, hovering above the Milky Way, there are two constellations—Cygnus the swan, her wings outstretched in full flight, and Lyra, the harp that accompanied poetry in ancient Greece, from which we take our word “lyric.” Between these constellations sits an unusual star, invisible to the naked eye, but visible to the Kepler Space Telescope, which stared at it for more than four years, beginning in 2009.
“We’d never seen anything like this star,” says Tabetha Boyajian, a postdoc at Yale. “It was really weird. We thought it might be bad data or movement on the spacecraft, but everything checked out.”
Kepler was looking for tiny dips in the light emitted by this star. Indeed, it was looking for these dips in more than 150,000 stars, simultaneously, because these dips are often shadows cast by transiting planets. Especially when they repeat, periodically, as you’d expect if they were caused by orbiting objects.
The Kepler Space Telescope collected a great deal of light from all of those stars it watched. So much light that Kepler’s science team couldn’t process it all with algorithms. They needed the human eye, and human cognition, which remains unsurpassed in certain sorts of pattern recognition. Kepler’s astronomers decided to found Planet Hunters, a program that asked “citizen scientists” to examine light patterns emitted by the stars, from the comfort of their own homes.
In 2011, several citizen scientists flagged one particular star as “interesting” and “bizarre.” The star was emitting a light pattern that looked stranger than any of the others Kepler was watching.
The light pattern suggests there is a big mess of matter circling the star, in tight formation. That would be expected if the star were young. When our solar system first formed, four and a half billion years ago, a messy disk of dust and debris surrounded the sun, before gravity organized it into planets, and rings of rock and ice.
In a recent paper, researchers have ruled out the possibility of faulty data or telescope jostling. Something appears to be blocking out the light, but it's not a planet, and the star is too old to be surrounded by the rings of debris that tend to circle around younger stars. Neither do the scientists think it could be caused by a recent collision.
That leaves just a few hypotheses. One is a cloud of comets that got pulled into orbit by a migrating star--if the comets are breaking up as they revolve around the star, that could cause the irregular pattern of dimming. The paper notes that this is the most promising explanation.
There is one other hypothesis, however.
“Aliens should always be the very last hypothesis you consider," Penn State astronomer Jason Wright told The Atlantic, "but this looked like something you would expect an alien civilization to build.”
Wright, and many other astronomers, have postulated that we could detect advanced civilizations through their technology. The idea is that as alien civilizations become highly advanced, they'll need more and more energy to fuel their high-tech lifestyles. Perhaps the aliens would position solar collectors directly around a star, filling the star's orbit until some or all of its light is blocked. These hypothetical alien megastructures are called Dyson swarms or spheres.
"It's hard to imagine how comets could block that much light--you need a huge number of them, and we must have caught them at a time when they happened to be all clumped together." That said, he acknowledges that Kepler studied 150,000 stars for several years, so it's possible the telescope just witnessed a very rare natural event.
To find out what's behind the star's mysterious dimming behavior, Wright and his colleagues want to listen in with the Green Bank telescope in West Virginia. They're hoping to spend a few hours listening for modulated radio waves that could indicate the presence of intelligent lifeforms.
"If we hear narrow-band modulated radio emissions coming from that star, I can't imagine any other explanation," says Wright. "Nature doesn't do that, it would have to be artificial."
If the team detects an interesting radio signature around the star, the next step would be to try to tune in with the Very Large Array in New Mexico. While the Green Bank telescope can reveal whether special radio waves are coming from the general area of the star, the VLA could tell the astronomers whether the waves are coming from the star itself.
"It's the best SETI target I've ever seen or heard of," says Wright.
In the current hyper-connected era, modern Information and Communication Technology systems form sophisticated networks where not only do people interact with other people, but also machines take an increasingly visible and participatory role. Such human-machine networks (HMNs) are embedded in the daily lives of people, both or personal and professional use. They can have a significant impact by producing synergy and innovations. The challenge in designing successful HMNs is that they cannot be developed and implemented in the same manner as networks of machines nodes alone, nor following a wholly human-centric view of the network. The problem requires an interdisciplinary approach. Here, we review current research of relevance to HMNs across many disciplines. Extending the previous theoretical concepts of socio-technical systems, actor-network theory, and social machines, we concentrate on the interactions among humans and between humans and machines. We identify eight types of HMNs: public-resource computing, crowdsourcing, web search engines, crowdsensing, online markets, social media, multiplayer online games and virtual worlds, and mass collaboration. We systematically select literature on each of these types and review it with a focus on implications for designing HMNs. Moreover, we discuss risks associated with HMNs and identify emerging design and development trends.
Understanding Human-Machine Networks: A Cross-Disciplinary Survey Milena Tsvetkova, Taha Yasseri, Eric T. Meyer, J. Brian Pickering, Vegard Engen, Paul Walland, Marika Lüders, Asbjørn Følstad, George Bravos
COPENHAGEN -- The Digital Age has brought with it a new way of thinking about manufacturing and operations, and the Internet of Things, which connects devices to the Web and to each other, will change the way we communicate and do business.
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