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Showing posts with label Science and Technology. Show all posts
Showing posts with label Science and Technology. Show all posts

Saturday, April 24, 2010

9 Ways Carbon Nanotubes Just Might Rock the World

Article Collected by AndhraColleges.com - Education is My Passion

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Nanotubes have been billed as the key to curing cancer, building space elevators, and creating real-world Spidermen. Whether they're totally tubular or just an overhyped pipe dream remains to be seen.
by Eliza Strickland  Oh carbon nanotubes, is there anything you can't do?
Nanotubes can be envisioned as one-atom thick sheets of carbon that have been rolled into tubes. Researchers know that when things get that small, they act a little weird, and labs around the world are now racing to capitalize on nanotubes' strange properties. With their extraordinary strength and fascinating knack for conducting electricity and heat, nanotubes are finding applications in everything from cancer treatments to hydrogen cars. These structures of carbon may be tiny—a nanotube's diameter is about 10,000 times smaller than a human hair—but their impact on science and technology has been enormous.
 
Here, we count down nine of the most enticing possibilities for these giants on the Lilliputian stage. They probably won't all pan out, but if nanotubes fulfill just a few of these predictions, they'll be worth the buzz.
 
9. X-traordinary X-rays
A new nanotube-based imaging system could take sharper, faster pictures that trump today's X-rays and CT scans. Researchers from the University of North Carolina say their device will be especially useful for imaging organs that are perpetually in motion, like the heart and lungs.
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In a traditional X-ray machine, a filament emits electrons when it is heated above a certain threshold, and those electrons fly through the body and hit a metal electrode on the other side, creating images; CT scans produce three-dimensional images by rotating the electron source. But the new system uses an array of carbon nanotubes that emit hundreds of electrons simultaneously as soon as voltage is applied to them. The system is faster than a regular X-ray machine because there are no filaments to warm up, and the multiple nanotube emitters can also take pictures from many different angles without moving.
 
8. Helping the Hydrogen Car
Cars powered by hydrogen fuel cells have been a clean energy dream for years, but they've been held back largely by the expense of making fuel cells. The Department of Energy estimates that half of a fuel cell's price tag comes from the platinum catalyst used to speed up the reaction that produces energy. But in February a team of researchers found that bundles of carbon nanotubes doped with nitrogen form a more efficient and more compact catalyst.
 
While carbon nanotubes are currently fairly expensive to produce, researchers note that the price has been plummeting. Researchers from the University of Dayton, Ohio note that nanotube production costs have fallen 100-fold since 1990, while no such price reductions are likely with platinum, a limited natural resource.
 
7. Diagnosis Via Nanotube
Spanish researchers say nanotubes can even help with an embarrassing medical problem, and have created a biosensor that can diagnose yeast infections (the irritating fungal infections that can take hold on the genitals). The scientists say their gadget provides a quicker diagnosis that today's typical method, in which a cell sample is taken and cultured in the lab to look for the presence of the Candida albicans fungus.
 
The researchers built a transistor that contains carbon nanotubes and antibodies programmed to attack the Candida yeast cells. When a cell sample is put on the biosensor, the interaction between the yeast and the antibodies changes the electric current of the device. The extremely conductive nanotubes record the change and allow researchers to measure how much yeast is present.
 
6. The Smallest Chips in the Land
Nanotubes could even spell the end of a building block of our modern world: the silicon-based computer chip. Several research groups have found ways to "unzip" carbon nanotubes to produce atom-thick ribbons of graphene. Like silicon, graphene is a semiconductor, but the nano-sized ribbons could be used to pack much more processing power on every computer chip.
 
Researchers have made graphene ribbons before, but never as easily—previously the ribbons were cut from larger graphene sheets, which offered little control over their size and shape. In contrast, unzipping nanotubes is a precise process. One research group first stuck the nanotubes to a polymer film, then used argon gas to etch away a strip from each tube to produce the nanoribbons.

5. Turn It Up!
The next application could make for a noisier world: Chinese researchers have found a way to make flexible, paper-thin loudspeakers out of nanotube sheets. The scientists say the technology could be used to add an auditory dimension to anything from clothing to magazines—and to prove their point, they put one on a waving flag.
 
The nanospeakers don't generate sound like conventional speakers, which make noise by vibrating the surrounding air molecules. Instead, they harness a phenomenon called the thermoacoustic effect, which is how lightning produces thunder. When an electric current runs through the nanotube sheets, they heat and expand the air near them, creating sound waves.
 
4. Taking Lessons from the Gecko
Real-world Spidermen could one day scamper up walls thanks to an adhesive made of carbon nanotubes. The substance mimics the design of gecko feet, which are covered in millions of tiny hairs that each end in a profusion of spatula-shaped tips. The lizards can defy gravity and walk up sheer surfaces because when those tiny tips are close to a surface, they induce a strong attractive force that operates on the atomic scale, known as the van der Waals force.

The nanotech version of this system is a glue that is ten times stickier than the gecko's feet. Researchers made arrays of vertically aligned nanotubes that were topped with shorter nanotube bits, like branching treetops. The adhesive worked on a variety of surfaces, including slick glass and rough sandpaper, but its hold could easily be broken by those who knew the trick. Just like a gecko lifting its foot away from the wall, researchers pulled the glue pad away at a 90-degree angle so that only the tips of the branching nanotube bits were touching the surface, and it easily came away.
 
3. Flexible, Bendable Electronics
Imagine a computer screen that could be bent, folded in half, and even crumpled like a sheet of newspaper, without affecting its function in the slightest. Researchers at the University of Tokyo took a step in that direction in May when they constructed a display made of organic light-emitting diodes (OLEDs) paired with a rubbery, nanotube-based conductor.
 
The organic compounds in an OLED system emit light when an electric current is passed through them, and they need no backlight, making them thinner than traditional displays. As nanotubes are natural semiconductors, they channel the electricity to the organic compounds. Researchers can envision enough technological applications to fill a World's Fair, including everything from food packages with interactive displays to artificial skin for robots and coatings for airplanes that would check the craft for wear and tear.
 
Low-cost, large-scale fabrication could be around the corner: The researchers used a cheap industrial printing process to deposit the nanotubes on a rubbery surface.
 
2. Space Elevator, Going Up
Carbon nanotubes are renowned for their superior strength, and in March researchers from the University of Texas manipulated that property to create a material that is simultaneously strong, stretchy, and nearly as light as air. The researchers made an aerogel (a low-density solid) out of nanotubes, and found that in was as strong as steel. Meanwhile, applying voltage to the material made it stretchier than rubber.
 
What possible uses could the world find for such a material? One idea is to fashion nanotube ropes to act as cables for a space elevator, which could lift astronauts, cargo, or even tourists into orbit. The 62,000-mile-long cables would have to be strong and flexible so they wouldn't break when buffeted by atmospheric storms and space debris, but light enough so they wouldn't collapse under their own weight.
 
1. Tumor Blitz
The tiny tubes could even end up as must-haves in cancer hospitals one day. In a recent study, researchers injected carbon nanotubes into kidney tumors in mice, and then directed a near-infrared laser at the tumors. The tubes responded to the laser blast by vibrating, which created enough heat to kill surrounding tumor cells.
In the group that received the highest dose of nanotubes followed by a 30-second laser treatment, the tumors shrank and completely disappeared in 80 percent of the mice. The procedure didn't appear to damage the animals’ internal organs, and left only a slight burn on the skin. But researchers haven't yet proven that nanotubes are safe and non-toxic, and say that much more research must be done before such procedures are ready to be tested in humans. 

Source: Discover magzine
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Friday, April 23, 2010

The Real Rules for Time Travelers

Article Collected by AndhraColleges.com - Education is My Passion

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Time travel may in fact be possible, but it wouldn't work like in Back to the Future. (For one thing, you don't have worry about your parents failing to create you—you already exist.)
by Sean Carroll   This piece is adapted from Cosmic Variance blogger Sean Carroll’s latest book, From Eternity to Here: The Quest for the Ultimate Theory of Time, which was published last month by Dutton.
The video still of the exploding clock to the right was captured by Biwa Studios in New York City. If you like the photo, the high-def, slow-motion video of the clock exploding is even better.
 
People all have their own ideas of what a time machine would look like. If you are a fan of the 1960 movie version of H. G. Wells’s classic novel, it would be a steampunk sled with a red velvet chair, flashing lights, and a giant spinning wheel on the back. For those whose notions of time travel were formed in the 1980s, it would be a souped-up stainless steel sports car. Details of operation vary from model to model, but they all have one thing in common: When someone actually travels through time, the machine ostentatiously dematerializes, only to reappear many years in the past or future. And most people could tell you that such a time machine would never work, even if it looked like a DeLorean.

They would be half right: That is not how time travel might work, but time travel in some other form is not necessarily off the table. Since time is kind of like space (the four dimensions go hand in hand), a working time machine would zoom off like a rocket rather than disappearing in a puff of smoke. Einstein described our universe in four dimensions: the three dimensions of space and one of time. So traveling back in time is nothing more or less than the fourth-dimensional version of walking in a circle. All you would have to do is use an extremely strong gravitational field, like that of a black hole, to bend space-time. From this point of view, time travel seems quite difficult but not obviously impossible.
 
These days, most people feel comfortable with the notion of curved space-time. What they trip up on is actually a more difficult conceptual problem, the time travel paradox. This is the worry that someone could go back in time and change the course of history. What would happen if you traveled into the past, to a time before you were born, and murdered your parents? Put more broadly, how do we avoid changing the past as we think we have already experienced it? At the moment, scientists don’t know enough about the laws of physics to say whether these laws would permit the time equivalent of walking in a circle—or, in the parlance of time travelers, a “closed timelike curve.” If they don’t permit it, there is obviously no need to worry about paradoxes. If physics is not an obstacle, however, the problem could still be constrained by logic. Do closed timelike curves necessarily lead to paradoxes?
If they do, then they cannot exist, simple as that. Logical contradictions cannot occur. More specifically, there is only one correct answer to the question “What happened at the vicinity of this particular event in space-time?” Something happens: You walk through a door, you are all by yourself, you meet someone else, you somehow never showed up, whatever it may be. And that something is whatever it is, and was whatever it was, and will be whatever it will be, once and forever. If, at a certain event, your grandfather and grandmother were getting it on, that’s what happened at that event. There is nothing you can do to change it, because it happened. You can no more change events in your past in a space-time with closed timelike curves than you can change events that already happened in ordinary space-time, with no closed timelike curves.
 
As we will see, the time travel paradox—the possibility of changing our past—seems intractable only because it conflicts with our notion of ourselves as beings with free will. Consistent stories are possible, even in space-times with closed timelike curves.
 
To illustrate this point, imagine that you stumble upon a time machine in the form of a gate. When you pass through it in one direction, it takes you exactly one day into the past; if you pass through in the other direction, it takes you exactly one day into the future. You walk up to the gate, where you see an older version of yourself waiting for you. The two of you exchange pleasantries. Then you leave your other self behind as you walk through the gate into yesterday. But instead of obstinately wandering off, you wait around a day to meet up with the younger version of yourself (you have now aged into the older version you saw the day before) with whom you exchange pleasantries before going on your way. Everyone’s version of every event would be completely consistent.
 
We can have much more dramatic stories that are nevertheless consistent. Imagine that we have been appointed Guardian of the Gate, and our job is to keep vigilant watch over who passes through. One day, as we are standing off to the side, we see a person walk out of the rear side of the gate, emerging from one day in the future. That’s no surprise; it just means that you will see that person enter the front side of the gate tomorrow. But as you keep watch, you notice that he simply loiters around for one day, and when precisely 24 hours have passed, the traveler walks calmly through the front of the gate. Nobody ever approached from elsewhere. That 24-hour period constitutes the entire life span of this time traveler. He experiences the same thing over and over again, although he doesn’t realize it himself, since he does not accumulate new memories along the way. Every trip through the gate is precisely the same to him. That may strike you as weird or unlikely, but there is nothing paradoxical or logically inconsistent about it.
 
The real question is this: What happens if we try to cause trouble? That is, what if we choose not to go along with the plan? Let’s say you meet a day-older version of yourself just before you cross through the front of the gate and jump backward in time, as if you will hang around for a day to greet yourself in the past. But once you actually do jump backward in time, you still seem to have a choice about what to do next. You can obediently fulfill your apparent destiny, or you can cause trouble by wandering off. What is to stop you from deciding to wander? That seems like it would create a paradox. Your younger self bumped into your older self, but your older self decides not to cooperate, apparently violating the consistency of the story.
 
We know what the answer is: That cannot happen. If you met up with an older version of yourself, we know with absolute certainty that once you age into that older self, you will be there to meet your younger self. That is because, from your personal point of view, that meet-up happened, and there is no way to make it un-happen, any more than we can change the past without any time travel complications. There may be more than one consistent set of things that could happen at the various events in space-time, but one and only one set of things actually does occur. Consistent stories happen; inconsistent ones do not. The vexing part is understanding what forces us to play along.
 
The issue that troubles us, when you get down to it, is free will. We have a strong feeling that we cannot be predestined to do something we choose not to do. That becomes a difficult feeling to sustain if we have already seen ourselves doing it.
 
Of course, there are some kinds of predestination we are willing to accept. If we get thrown out of a window on the top floor of a skyscraper, we expect to hurtle to the ground, no matter how much we would rather fly away and land safely elsewhere. The much more detailed kind of predestination implied by closed timelike curves, where it seems that we simply cannot make certain choices (like walking away after meeting a future version of ourselves), is bothersome.  The nub of the problem is that you cannot have a consistent “arrow of time” in the presence of closed timelike curves. The arrow of time is simply the distinction between the past and the future. We can turn an egg into an omelet, but not an omelet into an egg; we remember yesterday, but not tomorrow; we are born, grow older, and die, never the reverse. Scientists explain all of these manifestations of the arrow of time in terms of entropy—loosely, the “disorderliness” of a system. A neatly stacked collection of papers has a low entropy, while the same collection scattered across a desktop has a high entropy. The entropy of any system left to its own devices will either increase with time or stay constant; that is the celebrated second law of thermodynamics. The arrow of time comes down to the fact that entropy increases toward the future and was lower in the past.
 
A statement like “We remember the past and not the future” makes perfect sense to us under ordinary circumstances. But in the presence of closed timelike curves, some events are in our past and also in our future. So do we remember such events or not? In general, events along a closed timelike curve cannot be compatible with an uninterrupted increase of entropy along the curve. That’s a puzzle: On a closed curve, the entropy has to finish exactly where it started, but the arrow of time says that entropy tends to increase and never decrease. Something has to give.
 
To emphasize this point, think about the hypothetical traveler who emerges from the gate, only to enter it from the other side one day later, so that his entire life story is a one-day loop repeated ad infinitum. Take a moment to contemplate the exquisite level of precision required to pull this off, if we think about the loop as “starting” at one point. The traveler would have to ensure that, one day later, every single atom in his body was in precisely the right place to join up smoothly with his past self. He would have to make sure, for example, that his clothes did not accumulate a single extra speck of dust that was not there one day earlier. This seems incompatible with our experience of how entropy increases. If we merely shook hands with our former selves, rather than joining up with them, the required precision doesn’t seem quite so dramatic. In either case, though, the insistence that we be in the right place at the right time puts a very stringent constraint on our possible future actions.
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Our concept of free will is intimately related to the idea that the past may be set in stone, but the future is up for grabs. Even if we believe that the laws of physics in principle determine the evolution of some particular state of the universe with perfect fidelity, we don’t know what that state is, and in the real world the increase of entropy is consistent with any number of possible futures. A closed timelike curve seems to imply predestination: We know what is going to happen to us in the future because we witnessed it in our past.
 
Closed timelike curves, in other words, make the future resemble the past. It is set in stone, not up for grabs at all. The reason we think the past is fixed once and for all is that there is a boundary condition at the beginning of time. The entropy of the universe started very small (at the time of the Big Bang) and has been growing ever since. Ordinarily we do not imagine that there is any analogous boundary condition in the future—entropy continues to grow, but we cannot use that information to draw any conclusions. If we use a closed timelike curve to observe something about our future actions, those actions become predestined. That’s extra information about the history of the universe, over and above what we normally glean from the laws of physics, and it makes us uncomfortable.
If closed timelike curves exist, ensuring that all events are consistent is just as strange and unnatural to us as a movie played backward, or any other example of evolution that decreases entropy. It’s not impossible; it’s just highly unlikely. So either closed timelike curves cannot exist, or big, macroscopic things cannot travel on truly closed paths through space-time—unless everything we think we know about entropy and the arrow of time is wrong.
 
Life on a closed timelike curve seems pretty drab. Once you start moving along such a curve, you are required to come back to precisely the point at which you started. An observer standing outside, however, has what is seemingly the opposite problem: What happens along such a curve cannot be uniquely predicted from the prior state of the universe. We have the strong constraint that evolution along a closed timelike curve must be consistent, but there will always be a large number of consistent evolutions that are possible, and the laws of physics seem powerless to predict which one will actually come to pass.
 
In the usual way of thinking, the laws of physics function like a computer. You give as input the present state, and the laws return as output what the state will be one instant later (or earlier, if we wish). By repeating this process many times, we can build up the entire history of the universe, from start to finish. In that sense, complete knowledge of the present implies complete knowledge of all of history.
 
Closed timelike curves would make such a program impossible, as a simple thought experiment reveals. Hark back to the stranger who appeared out of the gate into yesterday, then jumped back in the other side a day later to form a closed loop. There would be no way to predict the existence of such a stranger from the state of the universe at an earlier time. Let’s say we start in a universe that, at some particular moment, has no closed timelike curves. The laws of physics purportedly allow us to predict what happens in the future of that moment. This ability vanishes as soon as someone builds a time machine and creates a closed timelike curve. Mysterious strangers and other random objects can then appear out of thin air and disappear just as quickly.
 
We can insist all we like that what happens in the presence of closed timelike curves be consistent. But that requirement is not enough to make the events predictable, with the future determined by the laws of physics and the state of the universe at one moment in time. Indeed, closed timelike curves can make it impossible to de-fine “the universe at one moment in time.” Ordinarily we can imagine “slicing” our four-dimensional universe into three-dimensional “moments of time.” In the presence of closed timelike curves, though, we generally will not be able to slice space-time that way. Locally—in the near vicinity of any particular point in space-time—we can always divide events into the “past” and the “future.” But we might not be able to do this throughout the universe. The warping associated with the closed timelike curve could cause our slice to twist back on itself, making it impossible to divide all of space-time into distinct moments.
 
We would therefore have to abandon the concept of determinism, the idea that the state of the universe at any one time determines the state at all other times. We would also have to abandon free will—because witnessing part of our future history implies some amount of predestination.
 
Do we value determinism so highly that we should reject the possibility of closed timelike curves entirely? Not necessarily. We could imagine a different way in which the laws of physics could be formulated—not as a computer that calculates the next moment from the present moment but as a set of conditions that are imposed on the history of the universe as a whole. It is not clear what such conditions might be, but we have no way of excluding the idea on the basis of pure thought.
 
All this may sound like vacillation, but it provides an important lesson. Some of our understanding of time is based on logic and the known laws of physics, but some of it is based purely on convenience and reasonable-sounding assumptions. We think that the ability to uniquely determine the future from knowledge of our present state is important, but the real world might end up having other ideas. If physicists discover that closed timelike curves really can exist, we will have to dramatically rethink the way we understand time. In that case, the universe could not be nicely divided into a series of separate “moments” of time.
 
The ultimate answer to the puzzles raised by closed timelike curves is probably that they simply cannot exist. If that is true, though, it is because the laws of physics do not let you warp space-time enough to create them—not because they let you kill your grandfather before you are born. 

Source: Discover magzine
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Are Black Holes the Architects of the Universe?

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Long known for their obliterating power, black holes may also have been a creative force: New evidence suggests that they gave order to the chaotic mess produced by the Big Bang.
by Andrew Grant  
Black holes are finally winning some respect. After long regarding them as agents of destruction or dismissing them as mere by-products of galaxies and stars, scientists are recalibrating their thinking. Now it seems that black holes debuted in a constructive role and appeared unexpectedly soon after the Big Bang. “Several years ago, nobody imagined that there were such monsters in the early universe,” says Penn State astrophysicistYuexing Li. “Now we see that black holes were essential in creating the universe’s modern structure.”
Black holes, tortured regions of space where the pull of gravity is so intense that not even light can escape, did not always have such a high profile. They were once thought to be very rare; in fact, Albert Einstein did not believe they existed at all. Over the past several decades, though, astronomers have realized that black holes are not so unusual after all: Supermassive ones, millions or billions of times as hefty as the sun, seem to reside at the center of most, if not all, galaxies. Still, many people were shocked in 2003 when a detailed sky survey found that giant black holes were already common nearly 13 billion years ago, when the universe was less than a billion years old. Since then, researchers have been trying to figure out where these primordial holes came from and how they influenced the cosmic events that followed.
In August, researchers at the Kavli Institute for Particle Astrophysics and Cosmology at Stanford University ran a supercomputer simulation of the early universe and provided a tantalizing glimpse into the lives of the first black holes. The story began 200 million years after the Big Bang, when the universe’s first stars formed. These beasts, about 100 times the mass of the sun, were so large and energetic that they burned all their hydrogen fuel in just a few million years. With no more energy from hydrogen fusion to counteract the enormous inward pull of their gravity, the stars collapsed until all of their mass was compressed into a point of infinite density.
The first-generation black holes were puny compared with the monsters we see at the centers of galaxies today. They grew only slowly at first—adding just 1 percent to their bulk in the next 200 million years—because the hyperactive stars that spawned them had blasted away most of the nearby gas that they could have devoured. Nevertheless, those modest-size black holes left a big mark by performing a form of stellar birth control: Radiation from the trickle of material falling into the holes heated surrounding clouds of gas to about 5,000 degrees Fahrenheit, so hot that the gas could no longer easily coalesce. “You couldn’t really form stars in that stuff,” says Marcelo Alvarez, lead author of the Kavli study.
Even as Alvarez’s computer model offered a glimpse into the universe’s infancy, it sowed confusion about what happened next. In 2007 scientists spotted a billion-solar-mass black hole that existed some 840 million years after the Big Bang, the earliest and most distant one ever observed. (Black holes themselves are invisible, but astronomers detect them by looking for the brilliantly hot gas that swirls around them before getting sucked in.) This past September another research team announced it had found a large, star-forming galaxy surrounding that black hole. These discoveries were puzzling, to say the least. About 400 million years after the Big Bang, the universe still consisted of scattered stars and small, starving black holes. Less than 500 million years later, it was full of monster black holes embedded in vast galaxies. How did things change so rapidly?
Penn State’s Li is trying to find out. While Alvarez’s simulations focus mostly on individual stars and black holes, Li studies the interaction of those objects and their influence on large-scale structures in the early universe. Her work shows that the first black holes were enveloped by halos of dense, invisible matter tens of thousands of times more massive. Together, these constituted protogalaxies, building blocks of today’s galaxies. During a period of frequent, violent collisions among the protogalaxies, their resident black holes experienced rapid growth spurts by merging with one another and gobbling up new supplies of gas and dust. A 100-solar-mass black hole ballooned into a billion-mass beast within 800 million years, and in especially dense regions that growth could have occurred even more quickly. During this dynamic period, Li’s model shows, black holes suddenly became a lot more star-friendly. Merging protogalaxies sent out shockwaves that compressed dense clumps of gas, helping trigger widespread star birth even in regions previously dominated by black hole radiation. In a remarkably short period of time, black holes shifted from lightweight bullies to supermassive centerpieces of star-breeding galaxies.
Although this simulation offers a comprehensive account of this formative epoch, Li concedes that her models are still just models; they are no match for direct observation. So while she and other theorists refine their calculations, other astronomers are using powerful telescopes to peer ever further back in time, looking for objects that are currently known only from computer simulations. “There are aggressive campaigns to search for the first supermassive black holes,” Li says. “We still may not have found the very first ones.” She says it would not surprise her if the earliest of these giant black holes appeared as little as 500 million years after the birth of the universe.
The recently refurbished Hubble Space Telescope will aid this search. This past April, one of Li’s Penn State colleagues discovered the burst of energy from a star that exploded, probably in the process of collapsing to form a black hole, when the cosmos was just 630 million years old.Hubble’s successor, the James Webb Space Telescope, will delve even deeper following its 2014 launch.
Soon, astronomers may be able to directly observe the improbable era when black holes were among the most important objects in the universe, helping to bring order to the Big Bang’s formlessness. “In theoretical and observational astronomy,” Li says, “this is the cosmic frontier.”

Source: Discover magzine
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20 Things You Didn't Know About... Eclipses

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by LeeAundra Temescu

1  The longest total solar eclipse of the century occurred on July 22 over India, Nepal, Bhutan, and China. It peaked over the Pacific Ocean, but even there the darkness lasted a mere 6 minutes and 29 seconds.
2  Fast and furious: The moon’s shadow zooms across Earth’s surface at up to 5,000 miles per hour.
 Canadian astronomer and renowned eclipse chaser J. W. Campbell traveled the world for 50 years trying to see 12 different eclipses. He ran into overcast skies every time.
4  Don’t repeat J. W.’s mistakes: Monsoon season throughout south Asia means that there is a good chance the eclipse this July will be clouded out too.
5  Just before full eclipse, dazzling “Baily’s beads” appear where sunlight shines through valleys on the moon. The last bead creates the impression of a diamond ring in the sky.
6  On eclipse-viewing expeditions, this phenomenon is frequently accompanied by a marriage proposal.
7  The beautiful symmetry of a total solar eclipse happens because—by pure chance—the sun is 400 times larger than the moon but is also 400 times farther from Earth, making the two bodies appear the exact same size in the sky.
8  In case you were thinking about relocating: Earth is the only place in the solar system where that happens.
9  Other planets get other kinds of fun, though. Jupiter can have a triple eclipse, in which three moons cast shadows on the planet simultaneously. The event is easily visible through a backyard telescope.
10  The Chinese word for solar eclipse is shih, meaning “to eat.” In ancient China people traditionally beat drums and banged on pots to scare off the “heavenly dog” believed to be devouring the sun.
11  Then again, China also produced the first known astronomical recordings of solar eclipses, inscribed in pieces of bone and shell called “oracle bones,” from around 1050 B.C. or earlier.
12  By comparing those ancient records with modern calculations of eclipse patterns, scientists have determined that the day is 0.047 second longer today than it was back then.
13  Tidal friction, which causes that lengthening of the day, is also making the moon drift away. In about 600 million years it will appear too small to cover the sun, and there will be no more total solar eclipses.
14  In any given location, a total solar eclipse happens just once every 360 years on average.
15  Luckiest place on Earth Carbondale, Illinois, will beat the odds: Folks there will see an eclipse on August 21, 2017, and again on April 8, 2024.
16  In contrast, everyone on the night side of the world can see a lunar eclipse, where the moon slips into Earth’s shadow.
17  During a total lunar eclipse, the moon takes on a deep reddish hue due to the sunlight filtering through our atmosphere—the cumulative glow of all the world’s sunsets.
18  While stranded in Jamaica, Christopher Columbus was famously saved by the lunar eclipse of February 29, 1504, which he had read about in his almanac. After a fracas with the locals, Columbus warned that the moon would disappear if they did not start supplying his men with food.
19  When the moon vanished, the locals promptly complied, and Columbus breathed a huge sigh of relief: His almanac was calibrated for Germany, and he was not sure that he had adjusted correctly for local time.
20  Who knows—it might be useful to you, too. The next lunar eclipse visible from the United States will take place on December 21, 2010.

Source: Discover magzine
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20 Things You Didn't Know About... Hurricanes

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A typical hurricane releases some 600 trillion watts of heat energy, equivalent to 200 times the world’s total electrical generating capacity.

by Jocelyn Rice  1  Our word for these storms comes from Hurakán, a one-legged Mayan deity who summoned the Great Flood from his perch in the windy mists.
2  The Mayans built their major cities inland away from flooding, showing a better understanding of Hurakán’s rages than the engineers who designed the New Orleans waterfront.

3  In 1609 a group of English settlers en route to Virginia were struck by a hurricane and washed ashore at Bermuda—an event that reportedly helped inspire Shakespeare’s Tempest.

4 Hurricanes laid waste to so many powerful armadas that, during the Spanish-American War, President McKinley declared that he feared the storms more than the Spanish navy. In response he established a network of storm-warning stations, the forerunner of today’s National Hurricane Center.
 
5  During World War II, a British flying instructor, Colonel Joe Duckworth, bet his pilots he could fly straight into a hurricane. Amazingly, he succeeded.
 
6  Hurricane forecasts today rely on Air Force pilots who zig zag through the eye, releasing dropsondes—parachute-equipped tubes containing instruments that measure pressure, temperature, humidity, and wind speed.
 
7  In North America we call them hurricanes, but in the western Pacific the same storms are known as typhoons. To avoid a tedious argument, meteorologists call them all tropical cyclones.
 
8  Due to the earth’s rotation, hurricanes spin counterclockwise north of the equator and clockwise south of it.
 
9  And once and for all: No, your flushing toilet does not do the same thing.
 
10  Most Atlantic hurricanes are born off the western coast of Africa, where warm water and a cool, windy upper atmosphere conspire to create a spiraling storm.
 
11  Activity peaks this month, when ocean-surface waters are warmest. Nearly half of all tropical cyclones occur in September.
 
12  We’re going to need a bigger windmill: A typical hurricane releases some 600 trillion watts of heat energy, equivalent to 200 times the world’s total electrical generating capacity.
 
13  Hurricanes unleash torrential rains, violent thunderstorms, and even tornadoes. But their deadliest component by far is the storm surge, the chunk of ocean pushed ashore by winds that can gust up to 200 miles per hour.
 
14  In 1970 a 30-foot storm surge claimed at least 300,000 lives in East Pakistan (now Bangladesh).
 
15  The horrific event inspired the Concert for Bangladesh, the first major rock benefit concert. But most of the proceeds were impounded by the IRS until years later.
 
16  The largest known tropical cyclone was 1979’s typhoon Tip, which stretched 1,400 miles across the northwestern Pacific—the distance from Dallas to Washington, D.C.
 
17  That’s still nothing compared with Jupiter’s Great Red Spot, a seemingly eternal 400-mile-per-hour hurricane nearly twice the size of our entire planet.
 
18  The World Meteorological Organization started naming hurricanes in 1953. Now the organization moves through an alphabetical list of names on a six-year rotation, retiring hall-of-famer storm names like “Katrina” each season.
 
19  Want a storm to call your own? Bad news: The National Hurricane Center already has “a rather large file folder of nominated names.”
 
20  And be careful what you wish for. After “Cleo” was retired in 1964, a researcher at the center filled the slot with “Camille,” in honor of the daughter of famed hurricane forecaster John Hope. Five years later, hurricane Camille hit the Mississippi coast, killing 250.
Source: Discover Magzine
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20 Things You Didn't Know About... Light

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The first light in the universe, the light used to push spacecraft, and the light produced by kicking the head of a walrus.
by Leeaundra Kean   1 God commanded, “Let there be light,” but it didn’t happen for nearly half a million years. That’s how long after the Big Bang the universe took to expand enough to allow photons (light particles) to travel freely.
2  Those photons are still running loose, detectable as the cosmic microwave background, a microwave glow from all parts of the sky.
 
3  Light moves along at full “light speed”—186,282.4 miles per second—only in a vacuum. In the dense matrix of a diamond, it slows to just 77,500 miles per second.

4  Diamonds are the Afghan istan of gemstones: Any entering photon quickly gets bogged down. It takes a lot of pinging back and forth in a thicket of carbon atoms to find an exit. This action is what gives diamonds their dazzling sparkle.
 
5  Eyeglasses can correct vision because light changes speed when it passes from air to a glass or plastic lens; this causes the rays to bend.
 
6  Plato fancied that we see by shooting light rays from our eyes.
 
7  The Greek philosopher was not completely wrong. Like all living things, humans are bio luminescent: We glow. We are brightest during the afternoon, around our lips and cheeks. The cause may be chemical reactions involving molecular fragments known as free radicals.
 
8  Bioluminescence is the largest source of light in the oceans; 90 percent of all creatures who live below about 1,500 feet are luminous.
 
9  World War II aviators used to spot ships by the bio luminescence in their wakes. In 1954 Jim Lovell (later the pilot of Apollo 13) used this trick to find his darkened aircraft carrier.
 
10  Incandescent bulbs convert only 10 percent of the energy they draw into light, which is why Europe will outlaw them by 2012. Most of the electricity turns into unwanted heat.
 
11  In the confined space of an Easy-Bake oven, a 100-watt bulb can create a temperature of 325 degrees Fahrenheit.
 
12  Light has no mass, but it does have momentum. Later this year the Planetary Society will launch LightSail-1, attempting to capture the pressure of sunlight the way a boat’s sail gathers the wind.
 
13  Laser beams bounced off mirrors left behind by Apollo astronauts show that the moon is moving 1.5 inches farther from Earth each year.
 
14  Visible light makes up less than one ten-billionth of the electromagnetic spectrum, which stretches from radio waves to gamma rays.
 
15  Goldfish can see infrared radiation that is invisible to us. Bees, birds, and lizards have eyes that pick up ultraviolet.
 
16  Photography means “writing with light.” English astronomer John Herschel, whose father discovered infrared, coined the term.
 
17  Shoot now: The “golden hour,” just after sunrise and before sunset, produces the prettiest shadows and colors for photographs.
 
18  Day and night are everywhere the same length on the vernal equinox, which occurs this year on March 20.
 
19  Auroras light up the night sky when solar wind particles excite atoms in the upper atmosphere. Oxygen mostly shines green; nitrogen contributes blue and red.
 
20  But to the Inuits, auroras are spirits of the dead kicking around the head of a walrus.  Source: Discover magzine
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The Picasso of DNA


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Here is how to get an appointment with George M. Church, professor of genetics at Harvard Medical School, director of four organizations devoted to genomics, cofounder of four biotech firms within the past four years, scientific adviser to 17 ultralow-cost genome sequencing companies, and founder of the Personal Genome Project:
First, you send him an e-mail requesting a meeting. He will reply with the URL for a Web site that lists his current schedule. This, when printed out, proves to be a 10-page, single-spaced document in very small type that starts with “January 1, 2009: Holiday, New Year’s Day” and ends with “September 17, 2010: International Steven Hoogendijk Award 2010 for G. Church, Rotterdam, Netherlands.” Searching through hundreds of entries—as many as nine falling on a single day—you try to find an uncommitted hour. If successful, you contact either of Church’s two administrative assistants to propose a date, time, and place. Then you hope for the best.
When the magical day arrives, the first question I ask Church is how he can possibly direct, create, advise, and mastermind so many projects (as well as teach classes and supervise Ph.D. dissertations) without going crazy. “Well, I think it’s an assumption that I’m not crazy,” he says. “They all seem pretty much the same to me. They’re all integrated, and I guess what we try to do is—we try to do integration.”
If Church’s career has a single integrating theme, it is finding ways to apply the machinery of automation to the molecular basis of life, the genome. His infatuation with computers goes back to grammar school in Clearwater, Florida, when, at age 9, he built an electronic computer for a science fair. Genetics entered the picture in the spring of 1974. Then an undergraduate at Duke, Church typed into a computer all the transfer RNA sequences that were available at the time and folded each one into a three-dimensional structure, as RNA molecules were known to do. “I became obsessed with sequencing,” he says. The obsession never faded. Today his myriad projects all emerge from his impulse to know, unravel, depict, use, and—better yet—tinker with and even create the RNA and DNA codes that constitute the software of living systems.
That ambition has resulted in a raft of Church-inspired technological innovations. His automated genome-sequencing machine is driving the price of mapping a person’s entire genetic code down toward $1,000, almost unbelievably cheap considering that, less than a decade ago, the government-funded Human Genome Project spent roughly $3 billion to sequence a single genome. Low-cost sequencing has allowed Church to embark on a second venture, the Personal Genome Project (PGP), which aims to sequence the genomes of 100,000 volunteers for free. The project would provide the first extensive genome database that matches DNA to a wide range of traits—not merely physical attributes like height or eye color but also disease histories and personalities. The idea is to help inaugurate the field of personalized medicine, in which each individual would receive preventions and treatments tailored to his or her specific genetic makeup, along with predictions of future health issues...
 Source: discovermagzine
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