City Lights Could Reveal E.T. Civilization

City Lights Could Reveal E.T. Civilization

  10:51:00 PM    Science Lover

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In the search for extraterrestrial intelligence, astronomers have hunted for radio signals and ultra-short laser pulses. In a new paper, Avi Loeb (Harvard-Smithsonian Center for Astrophysics) and Edwin Turner (Princeton University) suggest a new technique for finding aliens: look for their city lights. "Looking for alien cities would be a long shot, but wouldn't require extra resources. And if we succeed, it would change our perception of our place in the universe," said Loeb.

If an alien civilization builds brightly-lit cities like those shown in this artist's conception, future generations of telescopes might allow us to detect them. This would offer a new method of searching for extraterrestrial intelligence elsewhere in our Galaxy. (Credit: David A. Aguilar (CfA))

As with other SETI methods, they rely on the assumption that aliens would use Earth-like technologies. This is reasonable because any intelligent life that evolved in the light from its nearest star is likely to have artificial illumination that switches on during the hours of darkness.

How easy would it be to spot a city on a distant planet? Clearly, this light will have to be distinguished from the glare from the parent star. Loeb and Turner suggest looking at the change in light from an exoplanet as it moves around its star.

As the planet orbits, it goes through phases similar to those of the Moon. When it's in a dark phase, more artificial light from the night side would be visible from Earth than reflected light from the day side. So the total flux from a planet with city lighting will vary in a way that is measurably different from a planet that has no artificial lights.

Spotting this tiny signal would require future generations of telescopes. However, the technique could be tested closer to home, using objects at the edge of our solar system.

Loeb and Turner calculate that today's best telescopes ought to be able to see the light generated by a Tokyo-sized metropolis at the distance of the Kuiper Belt -- the region occupied by Pluto, Eris, and thousands of smaller icy bodies. So if there are any cities out there, we ought to be able to see them now. By looking, astronomers can hone the technique and be ready to apply it when the first Earth-sized worlds are found around distant stars in our galaxy.

"It's very unlikely that there are alien cities on the edge of our solar system, but the principle of science is to find a method to check," Turner said. "Before Galileo, it was conventional wisdom that heavier objects fall faster than light objects, but he tested the belief and found they actually fall at the same rate."

As our technology has moved from radio and TV broadcasts to cable and fiber optics, we have become less detectable to aliens. If the same is true of extraterrestrial civilizations, then artificial lights might be the best way to spot them from afar.

Loeb and Turner's work has been submitted to the journal Astrobiology.

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Can Google Get Web Users Talking?

Can Google Get Web Users Talking?

  1:13:00 AM    Science Lover

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Voice-driven search is a futuristic idea, and may take some getting used to.

Credit: Google

The notion of asking a computer for information out loud is familiar to most of us only from science fiction. Google is trying to change that by adding speech recognition to its search engine, and releasing technology that would allow any browser, website, or app to use the feature.

But are you ready to give up your keyboards and talk to Google instead?

Over the last two weeks, speech input for Google has gradually been rolled out to every person using Google's Chrome browser. A microphone icon appears at the right end of the iconic search box. If you have a microphone built-in or attached to your computer, clicking that icon creates a direct audio connection to Google's servers, which will convert your spoken words into text.

It has been possible to speak Google search queries using a smart phone for almost three years; since last year, Android handsets have been able to take voice input in any situation where a keyboard would normally be used. "That was transformational, because people stopped worrying about when they could and couldn't speak to the phone," says Vincent Vanhoucke, who leads the voice search engineering team at Google. Over the last 12 months, the number of spoken inputs, search or otherwise, via Android devices has climbed six times, and every day, tens of thousands of hours of audio speech are fed into Google's servers. "On Android, a large fraction of the use is people dictating e-mail and SMS," says Vanhoucke.

Vanhoucke's team now wants using voice on the Web to be as easy as it is on Android. "It's a big bet," he says. "Voice search for desktop is the flagship for this, [but] we want to take speech everywhere."

Voice recognition is more technically challenging on a desktop or laptop computer, says Vanhoucke, because it requires noise suppression algorithms that are not needed for mobile speech recognition. These algorithms filter out sounds such as those of a computer's fan or air conditioners. "The quality of the audio is paramount for phone manufacturers, and you hold it close to your mouth," says Vanhoucke. "On a PC, the microphone is an afterthought, and you are further away. You don't get the best quality."



Google asked thousands of people to read phrases aloud to their computers to gather data on the conditions its speech recognition technology would have to handle. As people use the service for real, it is trained further, says Vanhoucke, which should increase its popularity. Data from users of mobile voice search shows that people are much more likely to use the feature again when it is accurate for them the first time.

A bigger challenge to getting users to embrace voice recognition on the desktop could be the existing tools for entering information, says Keith Vertanen, a lecturer at Princeton University who researches voice-recognition technology. "On the desktop, you're up against a very fast and efficient means of input in the keyboard," he says. "On a phone, you don't have that available, and you are often in hands- or eyes-free situations where voice input really helps."

Vertanen says people are less tolerant of glitches when using speech recognition on a desktop computer because of the close proximity of a tried-and-true way of entering text. He says users might find voice recognition more compelling on on other Internet-connected devices in the home. "Nonconventional devices like a DVR, television, or game console don't usually have good text input," he points out. Google TV devices can already take voice input spoken into a connected Android phone.

Vanhoucke acknowledges that speech recognition fulfills a more immediate need on phones, but argues that users are ready for it on conventional computers, too. "People will use it in ways that surprise us," he says. "At this point, it's still an experiment." Situations when people may have their hands full is one example, says Vanhoucke (although it should be noted that desktop voice search today still involves using the mouse to activate the feature).

Google isn't performing this experiment alone. The company is pushing the Web standards body W3C to introduce a standard set of HTML markup that allows any website or app to call on voice recognition via the Web browser, and has already enabled a version of this markup in the Chrome browser. For now, Google is the only major company with a browser able to use the prototype feature, but Mozilla, Microsoft, and AT&T are all working with the W3C effort.

"It's a collaborative effort that other browser makers are part of," says Vanhoucke. "Any designer can add it to their Web page. It's something anyone can use." Extensions for the Chrome browser that make use of voice input (like this one) have already appeared, and can be used to enter text on any website.

However, those extensions reveal that although Google's desktop speech recognition is accurate for search queries, it's not much good for tasks like composing e-mail.

Enabling the system to learn the personal quirks of each person's pronunciation, a feature already enabled on Android phones, could address that. Vertanen points out that the personalization learned through mobile search could easily be ported over to the desktop for people logged into their Google account. It could also make it possible for the technology to spring up elsewhere. "The advantage of Google's networked approach is that a [speech] model in the cloud can adapt to your voice in all these different places and follow you around, whether that's in your living room or in your car."


A Browser that Speaks Your Language The latest version of Google's Chrome shows the potential of HTML5.

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Scientists Find Universal Rules For Food-web Stability

Scientists Find Universal Rules For Food-web Stability

  8:11:00 PM    Science Lover

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New findings, published in the journal Science, conclude that food-web stability is enhanced when many diverse predator-prey links connect high and intermediate trophic levels. The computations also reveal that small ecosystems follow other rules than large ecosystems: differences in the strength of predator-prey links increase the stability of small webs, but destabilize larger webs.

A Juvenile African Bush Viper (Atheris chlorechis) with a small frog, at night.
Researchers found that food-web stability is enhanced when many diverse predator-prey links connect high and intermediate trophic levels. (Credit: iStockphoto/Mark Kostich)

Natural ecosystems consist of interwoven food chains, in which individual animal or plant species function as predator or prey. Potential food webs not only differ by their species composition, but also vary in their stability. Observable food webs are stable food webs, with the relationships between their species remaining constant over relatively long periods of time.

Understanding complex systems such as food webs present major challenges to science. They can either be examined by observing natural environments, or by computer simulations. To enable computer simulations of such systems, scientists often have to make simplifying assumptions, keeping the number of model parameters as low as possible. Yet, the computational demands of such simulations are high and their relevance is often limited.

Innovative methodology

Scientists from the Max Planck Institute for the Physics of Complex Systems (MPIPKS) in Dresden, Germany, have developed a new method that allows them to efficiently analyze the impact of innumerable parameters on complex systems.

"By using a method called generalized modeling, we examine whether a given food web can, in principle, be stable, i.e., whether its species can coexist in the long term," says Thilo Gross from MPIPKS. Complex ecosystems can thus be simulated and analyzed under almost any conditions. "In this way we can estimate which parameters will keep ecosystems stable and which will upset their balance."

The method can also be used for examining other complex systems, such as human metabolism or gene regulation.

Generalists stabilize, specialists destabilize

Applying this innovative modeling approach together with colleagues at the International Institute for Applied Systems Analysis (IIASA) in Laxenburg, Austria, and Princeton University, USA, the scientists have succeeded in discovering not just one, but several universal rules in the dynamics of ecosystems.

"Food-web stability is enhanced when species at high trophic levels feed on multiple prey species and species at intermediate trophic levels are fed upon by multiple predator species," says Ulf Dieckmann of IIASA.

The scientists have also identified additional stabilizing and destabilizing factors within ecosystems. Ecosystems with high densities of predator-prey links are less likely to be stable, while a strong dependence of predation on predator density destabilizes the system. On the other hand, a strong dependence of predation on prey density has a stabilizing impact on food webs.

Differences between small and large systems

A further important finding is that food webs consisting of only a few species behave qualitatively different from webs consisting of many species.

"Small ecosystems apparently follow different rules than large ecosystems," says Ulf Dieckmann. "Systems with fewer species are more stable if there are strong interactions between some species, but only weak interactions between others. For food webs with many species, exactly the opposite is true. Extremely strong or weak predator-prey links in nature should therefore be the rarer the more species a food web contains," he concludes.

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