Sunday, August 31, 2008

Highlights from the Blogosphere

This week's excellent bloggy reads:


The Intersection
Required reading for anyone curious about the candidate's stances on science policy issues.

Built on Facts
Falling bodies obey Newton's laws, even in Milton's Paradise Lost.

Cosmic Ray

Uncertain Principles

Sciencegeekgirl


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Friday, August 29, 2008

End the Week with a Lawsuit, End the World with the LHC.


Against CERN, that is. According to World Radio Switzerland and The Science of Conundrums, on August 26th, 2008 a group of mostly Swiss, German, and Austrian professors and scientists filed a lawsuit against CERN's Large Hadron Collider (LHC) in the European Court of Human Rights in Strasbourg. The group argues that the LHC poses a serious threat to the safety of surrounding European Union countries.

I'm not going to delve into the whole miasma of controversy surrounding LHC. But, I will (cheerfully!) describe those darned global-catastrophe-causing micro black holes. Intended to lightheartedly mock, not scare.

Micro black holes
are tiny versions of black holes, extremely dense regions of collapsed or dead stars, with enormously strong amounts of gravity that not even light can escape from. Scientists believe they reside all over the galaxy, but are impossible to find due to their small size. These little babies can be made by smashing subatomic particles together with extreme force. You would of course need a powerful particle accelerator to do this (like, say the LHC maybe?). The micro black hole created would be minuscule, barely existing and so hot it would evaporate quicker than the blink of an eye.

UNLESS: the LHC makes another micro black hole that isn't quite so hot and remains stable, and another, and another and another and another (you get the idea). So now there's a rowdy crowd of young micro black holes, hanging around the LHC, full of angst. Because they are so incredibly small they can seep through stuff, walls, solid ground, etc without anyone noticing. This crowd of micro black holes would eventually trail completely out of the LHC and head (very, very slowly) down, pulled by gravity to the center of the earth.

Any particles that happen to cross the path of traveling black holes will be sucked in by their gravity, making them heavier and stronger. More and more matter will be pulled in. Finally, the micro black holes will be big enough to merge together, forming even larger holes whose inescapable gravity will swallow up the Earth. Nowhere to run, nowhere to hide...

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Thursday, August 28, 2008

Bell Labs Ends an Era.

No, it won't immediately cure cancer or result in mega-profit making gadgets.

Nonetheless, a twinge of sadness ensnares the recent announcement that Bell Labs is terminating its basic physics research lab.

This is a lab that produced six Nobel prizes, along with the invention of the transistor, laser, and countless advances in computer science and technology.

Check out WIRED's "Bell Labs Kills Fundamental Physics Research". *Previously defunct link is now working!
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Wednesday, August 27, 2008

All in a Gamma Ray.

Have a look at the image above; you are viewing the first map of the sky made entirely of gamma ray wavelengths! The thin golden-orange streak across what looks like a blue egg is actually gas and dust accumulated in the plane of our Milky Way. These menacing little photons, gamma rays, are the most energetic in the spectrum, and are emitted from the nucleus of certain radioactive atoms.

The gamma rays situated in the Milky Way are caused by cosmic rays, super-fast (mostly proton) particles colliding with interstellar gas. In what once took years, NASA'S Gamma-Ray Large Area Space Telescope or GLAST produced the map in just 95 hours, using LAT (Large Area Telescope), which can scan the entire sky once every 3 hours. GLAST recently got a name change too. In honor of Enrico Fermi NASA has dubbed it the new "Fermi Gamma-Ray Space Telescope".

A harbinger of high-energy physics, Fermi won the Nobel Prize in 1938 for his work on neutrons, specifically artificial radioactivity, a phenomena brought about by impinging uranium with neutrons in a non-spontaneous reaction. This contrasts with natural radioactivity, which spontaneously occurs among certain elements undergoing nuclear decay.

Scientists expect that the Fermi Telescope will continue to stack up a long list of discoveries, including more new pulsars and possibly unraveling the mysterious workings of active galaxies, whose inner cores contain super-massive black holes.

Returning to the image, the bright spot on the lower left is a blazar, while the Crab Nebula lies to the right as another bright spot. Blazars are temperamental bundles of energy fueled by super-massive black holes, they sometimes spit out streams of high-energy plasma at nearly the speed of light. The Crab Nebula is leftover supernova byproduct that contains a spinning neutron star.
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Tuesday, August 26, 2008

Cow Compass?

Moooooove over. Cows can sense the Earth's magnetic field and use it to orient themselves in a north-south direction while grazing and resting, according to a new study by German scientists.

In what might be oddest use of Google Earth I've encountered yet, zoologist Hynek Burda and his team zoomed in on more than 8,500 unsuspecting cows in 300 pastures all over the globe.

Analyzing the satellite data, the team found that entire herds of cows will face either magnetic north or south as they go about typical sedentary activities like eating and sleeping, irrespective of the direction of the sun and wind.

But what about deer? Turns out they too can sense the giant magnet. Burda and researchers traveled to 241 fields in the Czech Republic, where they observed deer grazing in a north-south direction. Their body imprints left from a night in the snow further indicate that deer are orientated north-south while they sleep.

The origin of geomagnetism still isn't completely understood, but scientists believe the Earth's magnetic field is produced much like a bar magnet, by the motion of electrical charges. Inside the Earth, a spinning liquid metal core of iron and nickel generates electrical currents.

Evidence for this lies in "magnetic fossils" or molten rocks that hardened in a way that leaves distinct traces of the geomagnetic field's direction at that time. These rock specimens have shown that the magnetic field has reversed at least 171 times during the past 71 million years.

The geomagnetic field is important; it shield the Earth from solar wind (streams of gases that jet out of the Sun). The magnetosphere is a portion of space surrounding the earth that acts as a deflector, directing the solar wind off course and away from the Earth.

The next step is for scientists to figure out why animals align themselves in a magnetic north-south direction, some believe the behavior may relate to an anti-predator mechanism.
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Monday, August 25, 2008

Fly On, Zephyr.

It's a bit of a strange sight- three men running swiftly, each holding up an arm supporting a thin, toy-like aircraft. With one huge shove, the solar-powered, propeller-driven Zephyr-6 soared 60,000 ft into the sky, where it remained for the next 82 hours and 37 minutes. The UK-built plane has set an unofficial world endurance record for a flight by an unmanned aircraft.

Conducted at the US Army's Yuma Proving Ground in Arizona, the Zephyr-6 flight was a demonstration designed to woo the US military. It flew for more than 3 days on pure sunlight, and by night on solar-powered batteries it had recharged during the day. The flight beats the current official world record set by Northrop Grumman's Global Hawk in 2001. However, the achievement is technically "unofficial" because the Federation Aeronautique Internationale ( the world air sports federation that sanctions all record attempts) wasn't involved.

A melange of new technology, the Zephyr soaks up solar power using ultra thin amorphous silicon arrays pasted atop it's carbon fiber structured wings. As night falls, the plane is propelled by rechargeable lithium-sulphur batteries, which according to a Zephyr-6 developer have more than double the energy density of lithium-ion polymer batteries.

Military officials tend to love all things "unmanned", especially aircraft like Zephyr-6, which could be used for preliminary surveillance and battlefield communications.
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Sunday, August 24, 2008

Double Your Fun

It's been a very good week for some physics blogs, in terms of posts worthy of highlighting. So today we offer a special "Doubles" series of bloggy goodness.


Cosmic Variance:
And the answer is... Lucretius?

Forget the new gymnastics scoring, how do judges score the Decathlon?

Green Gabbro:
Who knew ice cream could be viewed as a form of igneous rock?

Apparently there's a scientific explanation for what happens when you leave that pint of Haagen-Daz in the freezer too long.

Built on Facts:
Illustrated by Olympic weight-lifting.

Illustrated by Olympic archery.

Dynamics of Cats:
Some advice for those looking to enter the field.

What's the deal with getting the "scoop" on fellow scientists? Steinn explains.


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Friday, August 22, 2008

The World's Ugliest Building

Is it just me, or does anybody else think the Beijing National Aquatics Center is hideous?

The idea of covering the building in plastic bubbles that mimic the structure of foam must have sounded cool at one time. And as a physics groupy, I probably would have voted for it if anyone had asked me in advance. Now that I've seen it, I have to say "not so much." It makes me cringe every time the NBC cameras stray across it.

Science-inspired art sometimes turns out well. At other times, it just doesn't work. Compare our own Alpinkat's rap to a music video from Fermilab, for example. I give the thumbs up to Alpinkat, but don't much care for the Fermilab video (to put it gently).

I also love Daina Taimina's crochet math proofs. While at least one physics comic book series looks pretty bad to me.


Reviews among physicists seem mixed on the child-like Einstein statue outside the National Academy of Sciences building in Washington DC. Some love it and some hate it, but I haven't met many physicists who fall in the middle. I love it, both because it's charming and because it has a weird acoustical secret that you can only experience by standing at the center of the star map inscribed on the ground at Einstein's feet and speaking to the statue.

I'm in search of other examples of good and bad art inspired by science. Let me know if you have any suggestions.

-Buzz
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2008 is Coolness.

While this doesn't explain why I come into the office every morning with a sweater handy and scarf draped around my neck (thanks to frigid and relentless office air conditioning), it might raise some eyebrows: 2008 looks like its going to be globally, the coldest year of the 21st century.

Meteorological data shows that for the first half of the year, temperatures were more than 0.1 Celsius cooler than any year since 2000. Despite this, 2008 still appears to be about the 10th warmest year since 1850 (there's nothing like a little broad comparison).

In any case, scientists believe the reason for the chilliness is La Nina, twin counterpart to El Nino. Both are extreme natural phases of a continuous climate cycle. They cause massive changes in water temperatures in the eastern Pacific Ocean, which in turn cool down the entire globe.

Physics plays a huge role in modern climate change. It allows researchers to explore tough (and often controversial) questions surrounding global warming and the like. For example, variations in solar radiation has been proposed as a possible cause of global warming, and viewed by some as an alternative explanation to the greenhouse effect (increase of carbon dioxide in the atmosphere). Areas of physics and mathematics like thermodynamics, electromagnetic radiation, and statistics are used to find solid evidence either supporting or debunking current theories of climate change.

But what about the bigger picture? Although mainstream media largely ignores this fact, climate change doesn't equal warmer temperatures every decade. It changes alright, but rather fluctuates in many directions- hot, cold, arid, wet, you name it, over vast periods of time. This little subtlety, that the earth is a multifaceted control system that doesn't just depend on one ingredient, makes physical models of our climate essential to figuring out how the whole stew comes together.

Highly complex climate models can predict future change based on how the earth, ocean, and atmosphere interact. Brad Marston, a physicist at Brown University, uses the drying of Lake Mead in between Nevada and Arizona, as an illustration. Scientists believe that less rainfall is occurring in the area due to global warming-related weather patterns.

Computer simulations can track rainfall patterns and predict possible consequences for the lake. Think of a set of Russian Matryoshka dolls, within each doll nests another, and another, and so on. Physical models can determine the larger-scale processes that affect rainfall, such as shifting storm tracks.
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Worst-Headline-of-the-Week Award

Obama's rise in politics may be spectacular, but it can't be meteoric, despite the title of this article on CNN.com.

Barack Obama: A meteoric rise

Meteors fall, they don't rise. Anybody have an idea for a more physically sound title?

-Buzz
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Thursday, August 21, 2008

Highlights from the Blogosphere

This week's good reads. 


Backreaction
Bee explains the equivalence principle.

Space Disco
The latest LHC end-of-the-world scenario: a fusion propagation wave!

Skulls in the Stars
Uncovering the science beneath the hype.

Symmetry Breaking
Band of scientists on quest for neutrinos cross their first critical hurdle.

io9
A combination of motion capture and cutting-edge computer graphics creates the most believable "virtual human" yet.

Cocktail Party Physics
Shooting craps and other games of chance offer insights into the calculus of probability.


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Big or Small, Take Your Pick of Black Holes

Medium-sized black holes either don't exist or are very rare, say astronomers of the new study. The smallest known black holes formed from exploding supernovas, and are about 10 times larger than the Sun.

Black holes in contrast, are billions of times larger than the Sun, and reside deep in the core of most galaxies. Middle of the road black holes are generally thousands of times larger than the Sun.

The results are based on a comprehensive analysis of globular cluster RZ2109, using the European Space Agency's XMM-Newton Telescope and the WM Keck Observatory on Mauna Kea in Hawaii.

Black holes are extremely dense regions of space that act kind of like cosmic vacuums, using their massive gravity to suck in nearby surroundings, gulping them into dark orifices.

Researchers first picked up the revealing X-ray signals of an active black hole, then went a step further to determine its size. A chemical spectrum of the cluster placed the black hole at just 10 times the mass of the Sun, making it very tiny. According to theory, a cluster with a small black hole cannot also house a medium one, leading the researchers to conclude that medium-sized black holes are either non-existent or extremely uncommon.

The findings refute the argument of some theorists that clusters should contain varying medium- sized black holes, between 1,000 to 10,000 times larger than the Sun. But "never say never", especially in science. The authors counsel that elusive middleweight holes might be located on the outlying regions of our universe, making them both faint and difficult to find.
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Wednesday, August 20, 2008

Back to the Fusion.

Greetings readers! After a short and sweet vacation, I'm back with a story from the Wall Street Journal, on average Joes who build homemade nuclear-fusion reactors as a hobby ( see, the WSJ isn't always abysmally bland).

Amateur fusioneers like Richard Hull (pictured) spend copious amounts of time in their basement laboratories, tinkering with things like Tesla coils, causing flashes and sparks to spurt out of their homes in an alarming display (at least to their neighbors). Tesla coils are used to generate high-voltage alternating current electricity.

But mainly, these folks pursue their ultimate goal of making usable nuclear-fusion reactors. They even have a "Neutron Club", and techincally anyone can be accepted, under the condition that they must be able to produce a workable homemade reactor that is able to fuse hydrogen isotopes like deuterium. Oh, and glowing is a must. Its gotta glow. So far, only 42 people have achieved the requirement and become official Neutron Club members.

Originally based on Philo Farnsworth's 1960s design ( he also invented the television), reactors are devices that can fuse atoms together to create energy. In a fusion reaction, hydrogen atoms coalesce to form helium atoms, X-rays, and neutrons, along with an abundant supply of energy. According to some fusion experts, the attractive part is the cleanliness of the process- it generates very tiny amounts of air pollution and radioactive waste.

Unfortunately, we have not yet been able to create a viable nuclear reactor that can be used practically for abundant, clean, nuclear power supply. For decades, scientists have been working furiously on ways to fuse atoms, to little avail. Fusors currently use more energy than they produce.

Right now we're stuck with fission reactors to generate nuclear power, where energy is created from splitting one atom into two atoms. A typical nuclear fission reactor splits heavy uranium atoms that create huge amounts of energy, but leave behind burdensome quantities of longevous radioactive waste.
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Friday, August 15, 2008

Highlights from the Blogosphere

This week's good reads:


WWdN: In Exile
Wil Wheaton goes roller-skating with his offspring and learns that Newton's laws of motion aren't limited to science class.

The Guardian/Improbable Research column
Find out why "crunchiness declines in the presence of a soggifying liquid."

JPL Blog
Josh Willis talks about climate change, randomness, and why it's a bad idea to bet against global warming.

Science Fair
The National Science Foundation created this set of 11 True/False questions. Give it a try!

Twisted Physics
The subatomic particles now have a Bill of Rights.

Radiolab
Brian Greene talks about the concept of multiple parallel universes.

Huffington Post
USC's Marty Kaplan 'fesses up to his true feelings for that big ol' accelerator in Switzerland.

Peter McGready
See what Kaplan's all passionate about with this virtual tour of the LHC by photographer Peter McCready

Built on Facts
Just what is the temperature inside your microwave oven when you're nuking that frozen dinner?

io9
Funky ferromagnetic art.

Swans on Tea
Just how much of your favorite caffeinated beverage would it take to prove fatal? Plug your weight and poison of choice into this handy "Death by Caffeine" online calculator to find out! And click here to find out the time frame used for the calculation of consumption.

LA Times Technology Blog
Video games you can play with your thoughts... and some well-placed electrodes.


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Tuesday, August 12, 2008

One Hundred Thousand Time's a Charm.

Despite 18 years of orbit and 2.72 million miles traveled, NASA's Hubble Space Telescope continues to dutifully make its way around the Earth.

Yesterday, the Hubble completed its 100,000 orbit in space. To celebrate, scientists aimed the telescope at part of a nebula near the star cluster NGC 2074 (about 170,000 light-years away from the Earth), capturing the dazzling display (see picture on left) on camera.

The Hubble as been around well, almost as long as I've been alive. In fact, many if not all of the pictures of space I saw growing up in the nineties were taken by the Hubble. It is no doubt an icon of American space exploration!

What is so remarkable about the telescope isn't just its nearly two decades of orbit, but the countless scientific discoveries it has made possible; including confirming the existence of black holes and finding evidence for an expanding universe.

Aside from a few dents here and there, the Hubble is still sturdy and functioning. That's quite a feat, considering its orbiting hardware has only been repaired four times since its launch in 1990. A fifth repair mission was scheduled for 2003, but was terminated after the space shuttle Columbia tragedy that brought seven astronauts to their deaths.

The fifth and last Hubble repair mission is now scheduled for October 2008, when space shuttle Atlantis carries astronauts up to install new equipment and repair broken instruments. The repair should prolong Hubble's life for another 5 years, until 2013.
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Monday, August 11, 2008

In Quest for Speed, Olympic Swimmers Use Physics.

In light of the recent, thrilling accomplishments of the U.S. men's Olympic swim team, I thought it proper to focus on just how much physics goes into every aspect of Olympic swimming- from training and pool design right down to those tiny swim suits.

In ultra competitive swimming, flow is everything. Understanding how a swimmers movements or force impacts the water as his or her body gracefully glides and pushes is key to understanding how motion affects flow. Here is where fluid mechanics comes in: to help swimmers measure the flow and force generated in a natural, seemingly unpredictable environment.

This year the U.S. team is equipped with the technology needed to "know the flow", thanks to a fluid mechanics professor at Rensselaer Polytechnic Institute in Troy, N.Y. Timothy Wei invented a new flow measurement tool designed to help swimmers move faster and more effectively, knocking off seconds from their lap times.

Using technology originally designed for aerospace research, the system works by taking actual flow measurements of the swimmers, in real-time with a video-based flow measurement technique known as Digital Particle Image Velocimetry (DPIV). It can identify important vortices, pinpoint the movement of the water, and determine how much energy the swimmer exerts.

Onto the Pool. The mammoth of a swimming pool in Beijing is more than than a giant concrete hole filled with water and chemicals. This pool's got speed. That is, it's specifically designed to make swimmers move faster. The Beijing pool is almost 10 feet deep; 3 feet deeper than previous Olympic-sized pools. Perfect water depth is essential to maximizing vision and orientation.

Water that is too deep can mess up vision and perception. However, its has to be deep enough to adequently dissipate waves and turbulence. The lane lines that divide the swimmers are designed with new technology that further dissipate turbulent water. The flatter the water remains, the better.

The pool is also wider than most, with 10 lanes instead of the old eight, and perforated gutters are installed on its side walls. This ensures that pesky waves created during the races don't bounce back into the lanes and slow down the swimmers.

Finally, the swim suits themselves are newly designed to decrease surface friction and hydrodynamic drag. Speedo's new LZR Racer worn by Phelps and others this year in Beijing is based on aerospace engineering principles that actually minimize muscle oscillations. The shark skin-like suit also stretches over more surface area, thereby compressing the swimmer’s body into a better hydrodynamic shape.
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Sunday, August 10, 2008

Highlights from the Blogosphere

Cosmic Ray

Skulls in the Stars

Stock Car Science
Good tires can make all the difference. A bit of NASCAR science from the author of The Physics of NASCAR

Star Stryder

Cocktail Party Physics
Science in the service of art and archaeology

Top Gear
One of the co-hosts of the BBC's long-running auto show, Top Gear, tests his hypothesis that the body of a car acts as a Faraday cage.



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Friday, August 08, 2008

Not So Smooth: Dark Matter in Lumps and Clumps

video

A team of cosmologists in the U.S. and Switzerland have created the most complex and intricate dark matter computer simulation yet. For a month, they followed what happens to billions of dark matter particles 20 years after the Big Bang, over a span of 13.7 billion years. The simulation provides, for the first time, a dazzling panoply of the dark matter structure of a typical galaxy; all the way down to extremely tiny, detailed scales. To view a bit of the action, check out the video above.

Dark matter doesn't give off light or heat, its invisible stuff that takes up a whole lot of space in the universe. As one can imagine, this makes understanding its composition very difficult. Scientists known dark matter exists because it appears to have mass, and therefore interacts with gravity.

In the past, scientists believed the obscure substance formed in smooth halos in the centers of galaxies. The new findings show that dark mater isn't quite as smooth-it aggregates in dense lumps and clumps. The discovery adds to what little is known about the nature of dark matter, and will more importantly fuel future research towards an understanding of what makes up the mysterious stuff.

The model is based on the cold or slow moving theory of dark matter. Accepted by most physicists, the theory suggests that cold dark matter is composed of stuff large enough to move slowly, forming in cold, large, clumps over time.
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Thursday, August 07, 2008

The Sometimes "Ghostly" Results of Citizen Science

GalaxyZoo is a pretty sweet project. It lets your average Joe, i.e., non-astronomer, take part in astronomy research online by classifying galaxies (Quick! Is that a spiral or an elliptical?).

Turns out there is no substitute for the good old human eyeball. Our windows to the world can spot unusual patterns in galaxies acutely and quickly; a lot better than computers. Perusing GalaxyZoo archives is how 25 year-old Dutch volunteer Hany van Arkel came across a strange image of a glowing, gaseous object with a hole in its center.

This "cosmic ghost" became all the buzz after Hanny posted about the image. The astronomers who created and run GalaxyZoo realized that what she had found was indeed mysterious: no one had any idea what Hanny's Voorwerp ( Voorwerp means "object" in dutch) was. The excitement brewed as talk that she may have found a new class of astronomical object surfaced.

Subsequently, astronomers all over the world peered through teleoscopes and analyzed data from satellites in space, trying to figure out exactly what Hanny's Voorwerp was. What they found was even more perplexing- the object didn't contain any stars. It was all extremely hot gas around 10,000 degress Celsius.

So what was illuminating the mystery object, enabling scientists and Hanny to see it in the first place? Astronomers took a look around nearby for a source of illumination and settled on galaxy IC2497. They believe that galaxy IC2497 once contained an intensely bright quasar, small objects that are incredibly far off in space and are thought to surround massive black holes in the centers of galaxies. Futhermore, scientists think this quasar was so powerful that light from the past still illuminates the nearby Voorwerp, even though the quasar itself died thousands and thousands of years ago.
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Wednesday, August 06, 2008

The Kind of Water You Might Not Recognize.

Unlike that bottle of Deer Park you take refreshing sips from, this water is a supercritical fluid- the hottest water ever found on Earth.

While scientists have managed to make both water and seawater supercritical in laboratories, the phenomena has never be observed in nature until now.

Supercritical fluids are highly compressed gases that have both gas and liquid-like properties. This combination gives them special properties that regular fluids don't have. Andrea Koschinsky of Jacobs University in Bremen, Germany along with a team of researchers discovered the unusual water just south of the Atlantic equator.

Because supercritical water is much denser that regular water, it continues to shoot rapidly out of hydrothermal vents (aptly known as black smokers), residing deep down at bottom of the Atlantic ocean.

Very little is known about how supercritical water vents operate, and the extremely hot temperatures don't help things either. Since actively drilling into the vents is currently impractical and dangerous (the massive heat would melt most of the equipment), scientists are relegated to the next best thing: computer simulations.

Supercritical water easily sucks essential minerals out of rocks and spews them into the ocean. Many scientists think the process is responsible for deep ocean floor-dwelling elements like copper, gold, and sulphur. Koschinsky speculates that up to half the manganese and one tenth of the iron found in our oceans may come from supercritical water vents.

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Highlights from the Blogosphere

Dynamics of Cats

Bad Astronomy

Built on Facts

Cosmic Variance

Talk Like a Physicist

io9



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Tuesday, August 05, 2008

Vitruvian Man Unleashed in Powerful New X-Ray Hologram.

Holograms, love em' or hate em', are everywhere. 3-D images of the Vitruvian Man, the famous da Vinci drawing, and the bacterium Spiroplasma milliferum are even popping up at the Lawrence Berkeley National Laboratory in California and the FLASH free electron laser facility in Hamburg, Germany.

Researchers at the two institutes created the sharpest, most intense X-ray holograms ever made, using new techniques that made the process thousands of times more effective than previous methods. The resolutions for these holograms are the best ever reported.

The X-ray hologram of the Vitruvian Man was less than two square micrometers (millionths of a meter, or microns), engraved with a nanowriter, an ultra-high resolution lithography machine that can generate an electron beam at extremely high energies, with very tiny diameters on the nanometer (billionths of a meter) level. It required a five-second exposure to the beam and had a resolution of 50 nanometers. The Spiroplasma milliferum hologram was made at 150-nanometer resolution and computer refined to 75 nanometers, and required a beam exposure of 15 femtoseconds (quadrillionths of a second).

Holography is a lot like photography, except your camera is a laser and the images produced are in three dimensions. Invented by Hungarian-born physicist Dennis Gabor (who snagged a Nobel Prize for it in 1971), a traditional hologram produces a 3-D image of an object using a reflected laser beam of visible light. Holograms are able to map the intensity of the light reflected by the subject much like regular photography, but can also record information about the interference pattern of the light waves.

In a similar process, X-ray holography uses X-rays instead of visible light. Lasers are essential to making holograms, as they produce coherent (all in the same phase) light. A beam of coherent light is shined through two adjacent holes- one showing the subject to be holographed, and the other a small reference hole. As the light scatters, the two beams combine and become jumbled, forming a 3-D image.

X-rays work better than visible light because they have a shorter wavelength and can therefore illuminate fine details. They are also more powerful, having the ability to penetrate into the nooks and crannies of the subject's matter and take note of differences in chemical composition.
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Friday, August 01, 2008

Anicent Greek Astronomical Computer a Little Less Mysterious

It's around 150-100 BC, and you (being the ancient Greek that you are) decide to spend the weekend calculating astronomical positions. What do you use? The only mechanical computer around: the Antikythera Mechanism.

Fast forward to the early 20th century, where divers discovered over 30 gears from clock-like mechanism in a bronze case off the Greek Island of Antikythera, between Kythera and Crete.

Ever since, scientists have been struggling to figure out how it actually works. Physicist Mike Edmunds and mathematician Tony Freeth, along with a team of researchers believe they've finally solved the mystery.

New findings from their study suggest that Greek technology was far more intricate and complex that previously thought. In other words, the Greeks dominated astronomy for a thousand years with this carefully crafted, almost perfect device.

After exhaustive work on the gears, the team was able to show that the mechanism could track astronomical movements with impressive precision, including monitoring the movements of the moon and the sun through the Zodiac. It could even predict eclipses and recreate the irregular orbit of the moon. As if that isn't enough, the calculator may have also predicted the positions of the planets.

Using powerful X-ray and imaging technology, researchers were able to examine the machine's fragments and hone in on fine surface details. But exactly what the ancient Greeks used Publish Postthe Antikythera mechanism for remains unknown, and next scientists aim to create a computer model and eventually a full replica of the machine, in the hopes of answering many lingering questions.
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