Making Rain Clouds With Lasers

Shooting lasers at the sky can make the germ of a rain cloud, a new study shows. In an experiment that smacks of science fiction, scientists used a high-powered laser to squeeze water from air, both indoors and out.


The study is among the first to propose a direct test of how quantum entanglement, an effect that inexorably links two electrons in a way that Einstein called “spooky,” could change the behavior of whole animals.

Although the technique is unlikely to be an instant rainmaker anytime soon, it could plant the seeds for more eco-friendly cloud manipulation.

“This is the first time that a laser was used to condense water from both laboratory experiments and from the atmosphere,” says Jérôme Kasparian of the University of Geneva, a coauthor of the study. The work appeared in the May 2 Nature Photonics.


Atmospheric scientists have been trying to build artificial clouds since the 1940s, with mixed success. The most popular method, shooting particles of silver iodide into the sky, relied on the fact that raindrops need something to condense around.

“It’s just like when you take a shower with hot water — it’s very humid in your bathroom, but it’s not raining,” Kasparian says. Water droplets need a surface to condense on, like a mirror in a bathroom or a speck of dust or pollen in the atmosphere.

Previous experimenters hoped droplets would form around flakes of silver, salt or other materials just like on a bathroom mirror. “The idea is, you provide more condensation nuclei, you get more condensation,” Kasparian says. “It seems obvious, but in practice no one could really prove that it works.”

Kasparian and colleagues took inspiration from a mist-making apparatus that was invented in 1911 to detect cosmic rays, highly energetic subatomic particles that come from deep space. A physicist named Charles Wilson noticed that when cosmic rays strike a sealed container filled with water vapor, they leave a visible trail of water droplets behind them. This works because the cosmic rays knock electrons off the water molecules, leaving behind charged particles that act like specks of dust for water to congeal around.

“Our idea was to mimic what happens in a Wilson chamber,” Kasparian says. “If you get some condensation with cosmic rays, we should get even more condensation with a laser.”

Kasparian and his colleagues tested this idea by shooting a high-powered infrared laser into a cloud chamber. The laser shot extremely short pulses of intense light, which each carrying several terawatts — or a trillion watts — of energy.

The view fogged up immediately. Droplets about 50 micrometers in diameter formed first, and grew to about 80 micrometers in diameter over the next three seconds. “The effect in the cloud chamber was very spectacular and visible by bare eye,” Kasparian says. “We expected an effect, definitely. But that magnitude was pretty much a surprise.”

Next, the researchers took the laser out in the backyard to try it on the sky. They rolled the laser, called “Teramobile” for its terawatt power and its mobility, onto the lawn behind the physics building at the Free University of Berlin on several nights in the fall of 2008. The clouds, if they formed, would be too distant to see with the naked eye, so the team used a second laser to confirm the cloudy view.

“It also worked quite well in the free atmosphere,” Kasparian says. “That was quite surprising, and a very good surprise.”

Kasparian thinks lasers could provide a more reliable and environmentally friendly way to build clouds. “If you can seed clouds and get some control or at least modulation on the weather, the implications are huge for agriculture, many other economic sectors, many aspects of human life,” Kasparian says. “There are potentially huge consequences.”

“It is a clever technique,” says John Latham of the National Center for Atmospheric Research in Boulder, Colorado. But he’s skeptical that laser-built clouds could actually make it rain on demand. “Rainfall production requires many conditions to be met,” he cautions.

Image: Jean-Pierre Wolf/University of Geneva
By Lisa Grossman, Science News

Newscribe : get free news in real time

Read More http://www.wired.com/wiredscience/2010/05/laser-clouds/?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+wired%2Findex+%28Wired%3A+Index+3+%28Top+Stories+2%29%29#ixzz0mvBT0TMY

Believing is Seeing: How Mindset Can Improve Vision

PhysOrg.com) -- How you see isn't just about how good your eyes are - it's also about your mindset, according to a study published in Psychological Science. For example, in one experiment, if someone was told that exercise would improve their vision, they saw better after doing an athletic activity - jumping jacks - than an unathletic activity with the same effect on heart rate - skipping.

The researchers, led by Ellen Langer at Harvard University, were interested in how the mind and body connect, particularly how mindset affects the body's performance. Langer has studied this kind of connection for decades. "Many of the things that we think we can't do are a function of our mindset rather than our abilities to do them," she says. In this case, she was interested in whether what we think affects how well we see.

People expect to see only the first few lines on traditional eye charts. Volunteers in an experiment who read a eye chart arranged in reverse order (the letters got progressively larger, with the giant "E" in the last row) saw a greater proportion of the smallest letters than when they viewed a traditional eye chart.

Another experiment took advantage of the belief that pilots have good eyesight. College students in the ROTC were brought into a flight simulator, given army fatigues to wear, and told to fly the simulator. They did simple flight maneuvers, then did an eyesight test by reading markings on the wings of planes ahead - actually lines from an eye chart. A control group of ROTC students was put in the same conditions, but they were told the simulator was broken, and that they should just pretend to fly the plane. The people who had performed like pilots, as opposed to those who just pretended, saw 40 percent better.

These findings suggest that visual acuity is influenced by mindset and might be improved by psychological means. Just being aware of this might help people improve their eyesight, says Langer - if they pay attention to when they can see well and when they can't, for example, or simply believe that they can see better when they aren't sitting in a dark room at the optometrist's office. These findings along with others from Langer's lab lead them to question how many of our limits are of our own making. The research is part of a larger inquiry into the psychology of possibility.

Provided by Association for Psychological Science

Source: http://newscri.be/link/1089861

Comparing China And India

 

I’ve been traveling around this week giving talks on my new Oxford University Press book, China in the 21st Century: What Everyone Needs to Know, and one of the works I took along to divert me on planes and trains (I started it while flying to D.C. on Monday and finished it on an Amtrak ride to New Jersey on Wednesday) was an excellent new Princeton University Press publication by Berkeley economist Pranab Bardhan. As soon as I dipped into Awakening Giants, Feet of Clay: Assessing the Economic Rise of China and India, one thing that struck me was how much it had in common with the book I've been promoting--and not just because each is a general interest work by an academic that has been issued by a press linked to a prestigious university.


Here's a rundown of some similarities between the two works:

1) Each is short. (Mine clocks in at 164 pages; Bardhan's at 172.)

2) Each strives to dispel some common misconceptions about China, including the notion that it will inevitably democratize as its economy grows.

3) Each has only a small number of footnotes and tends to steer clear of specialized terminology.

4) Each stresses the dangers of making firm predictions about what is to come, yet ends with a forward-looking chapter. The last one in Bardhan's book is called “Looking to the Future: Through the Lens of Political Economy,” while the “The Future" is the title of the last one in mine.

All this could suggest that I would have trouble enjoying Bardhan’s book because of a sense that it was in direct competition with mine. This was not, however, the case. I was able to take pleasure in reading and learning from it without any niggling worry that people who buy it won’t be tempted to purchase China in the 21st Century. This is because, for all the similarities between the two books, there are a pair of crucial differences between them.

The first relates to topical focus. Bardhan is an economist, so not surprisingly he is primarily concerned with economic issues. Those are not the sole focus of my book, which explores topics ranging from Confucian thought to consumer culture, from generation gaps to the World Expo. Bardhan has valuable things to say about non-economic topics (politics, the environment, etc.), but his attention remains fixed throughout on the dynamics of development.

The second contrast between our books is even more important: his is equally concerned with two different countries, whereas I concentrate on just one (albeit with a variety of brief forays into comparison). Bardhan makes his interest in a pair of countries clear in his book’s title and subtitle: Awakening Giants, Feet of Clay: Assessing the Economic Rise of China and India. (One thing I like about that title is that it is refreshingly free of any allusion to a totemic animal. No cliched “dragon” vs. “elephant” word play for him.)

Bardhan writes with remarkable clarity about complex issues, such as the widely varying ways that corruption can affect the economy, and the positive as well as negative legacy of the Maoist era for China in terms of its recent trajectory. (For example, he stresses the importance of the upsurge of literacy during the pre-Reform era, which meant that a relatively well-educated pool of workers were ready to contribute to the country's take-off after Deng Xiaoping came to power.) He also shows some welcome stylistic flair, quoting poetry to good effect in one section (how often do economists do that?) and slipping a lovely bit of alliteration into the title of a chapter: “Infrastructure: The Dazzling Difference.”

One thing that I was relieved to discover when I reached the end of the book was that, while I certainly gained new insights into many specific issues from reading it, nothing I came across in Awakening Giants caused me to wish I could go back and alter fundamentally anything about my own brief treatment of China-India comparisons in China in the 21st Century. This is hardly surprising, though, since one person I read to prepare to write that part of the book was Bardhan--a fact I acknowledge by listing one of his recent articles (that is available free online) in my book's “further readings” section.

There’s a final contrast between our two books worth noting. Only mine was written in a question-and-answer format, a hallmark of the “What Everyone Needs to Know” series of which it is part. And yet, when I got to the end of Awakening Giants, I definitely felt that most of the questions I had about the Chinese and Indian political economies (and I suspect these are ones that other Americans interested in Asia are likely to have as well) had been answered very effectively.

Jeff WasserstromBio
Professor of History, editor of the Journal of Asian Studies, author, most recently, of China in the 21st Century: What Everyone Needs to Know

Source: http://newscri.be/link/1089853