Physics Buzz

Butterflies Inspire Anti-Counterfeit Technology

2013-06-18T15:52:00.001-04:00

Image credit:

Creativity+ Timothy K Hamilton via Flickr

Rights information:

http://bit.ly/cGotEb

A Canadian company is fighting counterfeiters by employing one of the most sophisticated structures in nature: a butterfly wing.

To be precise, Nanotech Security Corp. in Vancouver is using the natural structure of the wings of a Morpho butterfly, a South American insect famous for its bright, iridescent blue or green wings, to create a visual image that would be practically impossible to counterfeit. The technology was developed at British Columbia’s Simon Fraser University, and licensed to the company.

The phenomenon Nanotech employs is similar to the way some animals, including male peacocks, produce iridescent colors: instead of using proteins and other chemicals to produce a hue, the creature’s feathers or scales play with light, using very tiny holes that reflect different colors or wavelengths. The Morpho does this with complicated scales on its wing that produce shimmering blues and greens.

Nanotech’s printed security image can be embossed on virtually any surface, including plastics, metals, solar cells, fabrics, and paper, according to Clint Landrock, Nanotech’s chief technical officer. They even could be embedded on pills and capsules to ensure they are genuine pharmaceuticals, instead of fakes.

“It lends itself to anything your imagination can come up with,” he said, “even brake pads.”

The work is another example of what scientists call biomimicry, which adapts nature’s solutions for innovative human devices, in this instance, nano-optics, a burgeoning new technology.

Researchers at the University of Michigan, for example, use nano-optics to print pictures and images without ink or dyes.

Landrock, one of the inventors, said the Simon Fraser researchers actually studied the shingled, patterned plates of a Morpho wing to see how it handled incoming light. The trick was to make artificial “nano-hole arrays,” which produce similar iridescent efforts with simpler structures. That way, the company can mass-produce billions of nano-holes.

“We can tune the colors by changing the geometry of those hole arrays,” he said.

They used a method similar to the manufacturing of computer chips, known as electron beam lithography, to produce master nano-hole patterns embossed on silicon or quartz.

They worked at the scale of nanometers. A single nanometer is hundreds of times smaller than even the tiniest bacterial cell. The holes in the template ranged from 50 to 300 nanometers in diameter, spaced 300-600 nanometers apart. The process takes from a few hours to a couple of days to produce a master pattern, or mask, depending on the size of the mask and the number of structures. After the mastering, a second process grows the image on nickel. From there it can be transferred to any material.

The entire image could be large enough to be seen from a distance, and, if embossed on high-priced items like designer handbags, would make it easy to spot the phonies, said Doug Blakeway, Nanotech’s CEO.

“If you had a hand bag and the clasp on it had the company’s logo on it you would see it and it would turn on and off in very bright colors.” Simply moving the item or the observer would make the color flicker.

There shouldn’t be any issue with putting the image on a capsule or pill, he said. You could see the brand on it to be sure the medicine was authentic. It would not require Food and Drug Administration approval because the image would not involve dyes or pigments so medicine would not be altered in any way.

Counterfeiting this technology is unlikely, Landrock said. The image would be very difficult to reverse engineer, and expensive because of the equipment needed. The image is much brighter than any created by any other technology, he explained, including holograms.

“I like to say it is similar to describing how an old CRT television display looks compared to a new Ultra HD LED TV,” he said “They may be showing the same thing but you would never mistake one for the other.”

Landrock said the most logical use for the technology would be an anti-counterfeiting device on bank notes.

A nano-optics image can be embossed on coated paper, but many countries, including Canada and Australia, have switched to polymer plastics for its bank notes, which are even more receptive to nano-optics images. Those bills last much longer than U.S. paper currency and are much harder to counterfeit.

Since the company has only begun commercializing the technology, no country has yet signed up.

Even so, it is unlikely the U.S. dollar will see nano-optics any time soon. U.S. bank notes do not even use holograms, common in other currencies, or coated or polymer paper, according to Darlene Anderson, a spokeswoman for the U.S. Bureau of Engraving and Printing.

The reason for the conservative bills, is that most American currency is held overseas, where it is often used as the reserve currency for the undeveloped world, said Owen Linzmayer, publisher of Banknote News, an industry observer. A radical change to U.S. bills could upset international economies and flood the country with the old bills.

The same restraints do not apply for Gucci handbags.

--Joel N. Shurkin, Inside Science News Service

_________________________________________________________________________________

Joel Shurkin is a freelance writer based in Baltimore. He is the author of nine books on science and the history of science, and has taught science journalism at Stanford University, UC Santa Cruz and the University of Alaska Fairbanks.

Angry Birds: Furious Forces! Review

2013-06-17T14:41:00.002-04:00

Image Credit: National Geographic

With over 1.7 billion downloads, the suite of Angry Birds games has dominated the mobile gaming market for the past few years. During the game's meteoric rise, one science writer has taken a keen interest in the physics behind this game.

Physics professor and Angry Birds aficionado Rhett Allain has been blogging about the physics behind the various angry birds with his motion-tracking software and physics know-how. Now, he's written a book to boot!

But Allain's new book, Angry Birds Furious Forces!, takes a different approach than many of his blog posts. Instead of providing the detailed analysis of his blog posts, Allain incorporates the Angry Birds universe to teach five basic areas of physics: mechanics, sound and light, thermodynamics, electricity and magnetism, and "particle physics and beyond."

Nonetheless, this book only vaguely resembles a physics textbook. It's full of bright graphics, costumed Angry Birds, and a few of National Geographic's iconic photos overlaid with some Angry Bird Photoshop magic. Consequently, I found myself breezing through the five sections of the book fairly quickly.

The heart of each section covers a few basic physics principles such as circular motion, the Doppler effect, and the speed of sound. Nearly every page is also littered with fun facts (e.g. "salted ice can be cold enough to 'burn' your skin) and related experiments you can do at home.

Profile Page for Matilda, the explosive-egg-dropping bird.
Image Credit: National Geographic

The Angry Birds themselves make appearances throughout the book, and most have their own profile page detailing their "favorite tactic" and the "physics at play." The connection between some of the birds and their associated physics principles, however, is usually pretty tenuous. The small blue birds that break apart, for instance, are likened to particles in the solar wind. That's a bit of a stretch.

But it seems National Geographic and Allain weren't trying to replicate the highly detailed analyses found on Allain's blog. For the book, the Angry Birds are used more as an effective hook — attaching a game with 1.7 billion downloads and a global following certainly catches a few eyes. But the heart of this book teaches basic physics principles in an accessible way. Here, Allain succeeds.

The explanations throughout the book are lucid, especially when covering relatively complex topics such as sound waves, particle physics, and relativity. Even with a physics background, I learned quite a few new things from the various physics facts interspersed in the book. Although I found the book quite enjoyable, I imagine tweens and early teenagers would gain the most from reading Furious Forces!

An example page from Furious Forces!
Image Credit: National Geographic

On top of that, the book's eye-popping graphics serve as a reminder of the book's video game roots. The book's editors have deftly overlaid Angry Birds (and their avian commentary) to beautiful wildlife photography, as you can see above.

Furious Forces! definitely departs from Allain's writing on his blog, but I found it a light, entertaining read. Regardless of your training in physics, you'll probably learn something new after reading it (like the fact that every type of Angry Bird has its own name). You can find Furious Forces! on Amazon for about 10 dollars, and proceeds of the book support the National Geographic Society.

How to Perfectly Swim the Chesapeake Bay

2013-06-14T16:31:00.000-04:00

I started this post yesterday thinking this would be a simple, interesting math problem. Turns out I was wrong. Here it is, a day late and one equation short. This past Sunday I participated in the Great Chesapeake Bay Swim. It's a swim that starts on the western shore of the bay at Sandy Point State Park and ends 4.4 miles later on the eastern shore at Hemingway's Marina. The rules are simple, get in the water and swim to the other side while staying between the spans of the Chesapeake Bay Bridge. The Bay Swim is an Annapolis tradition and has been going on for 22 years. The currents make it a very challenging course, meaning that by the time I'd finished I'd most likely swum farther than the 4.4 miles of the bay. I also had to constantly change my swimming angle with respect to the shore to make sure I didn't get sucked out to sea. After recovering from the "race" I wanted to go back and find out 3 things; the angle at which I should have been swimming to go forward but not get swept out, how far I actually swam, and if I was doing this perfectly, how long should it have taken me. So here are my calculations. Hopefully this will be useful to someone next year!

First a little background on the bay and swimming in it. Swimmers go from west to east. The most significant challenge is the currents caused by the tides. The tide changes quickly and can be very strong. It can take swimmers anywhere from 1:45 to 4 hours to reach the other side of the bay and the tides go from low to high in as little time as 7 hours. The race is usually timed so that the majority of racers will start out with a bit of tidal current pushing them north, swim the majority of the race during the wonderful still water of slack tide (when the tide is changing directions) and finish as the tide starts to go out, creating a current pulling swimmers south.

This year, however, we were not so lucky. The race started during slack tide and we felt an increasing pull south as we swam across. As we were getting more tired, the current was getting stronger. When one is bobbing in the bay for an extended period of time, one has lots of time to think. I remembered back to an intro physics problem of a boat in a current trying to get to the other side. The boat had to point at the correct angle to get across successfully. I spent a long time trying to experimentally figure out the correct angle in the bay. Really, I ended up feeling more like this guy.

Here is a simplified diagram of the situation:

I made some pretty big assumptions here. First, all speeds are in mph, I had to convert the current speed from knots to mph. I looked at the tidal currents for that day and they started at roughly zero and after about 3 hrs were at 1 mph and they increased pretty linearly. I'm also assuming that I kept moving forward at 2 mph throughout the whole thing. This is a good estimate at my speed in still, open water.

The first thing I wanted to know was the optimum angle at which I should swim. This would be super easy if the current were constant, but isn't too difficult to do with a changing current. Since I want the direction I'm headed to be perpendicular to the direction of the current, I can move the arrows around to be a right triangle.

If I want to successfully finish the race I need to make sure I am going north at least as fast as the current is pushing me south. If I want to finish as fast as possible, I don't want to be going farther north than I have to. This means that I want my northern component to exactly equal the current.

And now I want to see how my angle would change with time so I have to solve for:

A graph of that can give a better idea of which way I should be heading(y is theta in degrees and x is time):

When I start out I should be heading directly towards the other shore but as I swim along, I'll gradually be turning north by about 10 degrees an hour. That may not seem too significant, but every 10 degrees I turn north means a little bit less forward motion towards the other shore and it's a bit more likely I'll get swept out to sea if I stop to fix my goggles. By about 3 hours in, only 2/3 of my forward motion is getting me to safety and 1/3 is going to fight the current.

What is extremely interesting is that by the end of the swim (around 3 hrs) I had decided to swim at about 45 degrees towards the north which means I was going more slowly than I needed to be. I am going to remember that for next time.

The other two questions, how fast could I have gone and how far did I actually swim, are much, much more difficult. In fact, I still haven't been able to solve them. I'll try this weekend and hopefully put up an addendum to this post next week.

Why were those two questions so hard to answer? It seems like it should be pretty obvious to figure out how far you've gone or how long it should take you to go some distance as long as you know the velocity. In this case R(t) is my velocity towards the shore and once I set foot on the beach at Hemingway's Marina I will have gone 4.4 miles. Distance traveled is the velocity times the time you've been moving. The problem is that my velocity is changing with time. This means I have to add up my velocities at every second in time and multiply by that small chunk of time.

Doing that is called integrating and it is extremely useful but can also be rather complicated. I can find R(t) now that I know the optimum angle of attack, but it isn't easy to integrate. However, I can graph it easily enough and show how my velocity changes over time. It turns out that if current kept increasing in the same way and the bay was longer than 4.4 miles, after 6 hours of swimming I would no longer be able to keep it up (y is velocity east and x is time).

I start out going 2 mph towards the opposite shore and then after about 3 hours I'm down to 1.7 mph. It drops off much more quickly after that.

Hopefully I can do some integrals this weekend and figure out how far I swam and how long it should have taken me. I started doing this calculation to get a better sense of why my time was so much slower than what I thought it should be. What I've managed to do in the process is convince myself that I did indeed swim quite slowly, I did a terrible job of heading in the right direction and I'm not as good at doing physics problems as I used to be. But, I finished the bay (with no wetsuit) and I did most of this calculation so I guess I also learned that I have more persistance than I thought. Though I think my boss summed it up best by saying "It shouldn't take you longer to do the problem than it took you to swim the bay!"

PODCAST:The Physics of Vinyl (and other records)

2013-06-12T12:47:00.001-04:00

This week on the Physics Central Podcast we're talking about the physics of vinyl records. How do records record sound, and why can't you make a record out of wood or ice or some other material? (A: You CAN! It just might not sound very good!).

One of my favorite bands, the Swedish-based Shout Out Louds, recently released a new album, featuring a song called "Blue Ice." The song is about "fading devotion." As part of their publicity efforts to promote the album, the band sent 10 lucky individuals a kit that allowed them to create a record of the new song out of ice. Here's a video showing how to make an ice record (you need a pre-stamped mold), and a recording of the final product (not great, but still awesome):

In this week's podcast we'll talk about why an ice record sounds so noisy compared to a vinyl record. Even though the sound quality of the ice record isn't great, it demonstrates the fundamental principle behind LP's: any material can serve as a record, as long as it can hold the imprint of a sound wave.

Image of a record groove, captured by Chris Supranowitz, an optics researcher at the University of Rochester.

Various materials will do this better than others. Vinyl not only holds the imprint of the sound wave well, it's also cheap and durable. People in the former Soviet Union made records out of discarded X-ray film (they played well, but didn't last long). Engineer Amanda Ghasshaei (who has a B.S. in physics) made records out of wood, acrylic and paper. Here's David Bowie's Rebel Rebel on wood:

Like the ice record, these records have a lot of accompanying noise. In addition, they're likely to damage the needle on a record player over time. But the process is interesting. Ghasshaei used a laser cutter to carve the grooves into the wood, and she shares instructions on how you can make your own (assuming you have access to the right tools). She's also printed records with a 3D printer; they also don't sound great. But, perhaps this is a starting point to improve these methods of record production. In the same way that book publishers now have print-on-demand options for rare or out-of-print books, perhaps record producers will one day use 3D printers or laser cutters to create single copy LP's.

Listen to this week's podcast (and subscribe via iTunes!) for more about the science of sound and vinyl!

Additional:
You can listen to samples of different sound wave shapes (square, triangle, sawtooth) here.

Luis Alvarez: Master Inventor

2013-06-11T17:10:00.000-04:00

Luis Alvarez
Image: Dutch National Archives

The physicists of yesteryear were a colorful bunch, often dabbling in one discipline for a time before jumping into something entirely new. To many, the bongo-playing, safe-cracking, Nobel Prize-winning Richard Feynman is the quintessential renaissance-man scientist.

There were others. One of Feynman's contemporaries, Luis Alvarez was the man who could seemingly build anything. He was everywhere and played an important role in a surprising number of the big physics discoveries during the middle of the century.

As a graduate student at the University of Chicago in the mid-1930s, he kluged together a series of Geiger counters onto a wheel barrow, turning it into a state of the art particle detector. He brought it to the top of a hotel in Mexico City, a place with the perfect mix of altitude and latitude to catch the then mysterious solar wind. There he found that the particles flew in mostly from the west, meaning they had to be protons with a positive charge moving laterally across Earth's magnetic field.

Alvarez then joined Ernest Lawrence's Rad Lab at Berkley and started making major contributions to fundamental nuclear science. He proved a process called K-electron capture can happen, where an atom's innermost electron is absorbed by a proton in the nucleus and emits an X-ray.

Even more importantly however, he discovered the process that would ultimately lead to the hydrogen bomb. He used his 60-inch cyclotron to bombard the hydrogen isotope deuterium (one proton and one neutron) with more deuterium and measure the products. It turned out, contrary to what people had predicted, that the hydrogen-3 isotope it sometimes produces was unstable, while helium-3 wasn't. Years later, physicists would harness this instability for use in fusion experiments.

Then World War II started, and Alvarez went to MIT and invented a radar system for planes to land in bad weather. Halfway through the war he transferred to Los Alamos where scientists were building the first atomic bomb. After arriving in New Mexico, he built the firing mechanism for the bomb, and a way to determine its strength by recording changes in air pressure. When the bombs were dropped on Hiroshima and Nagasaki, he flew in a chase plane to measure the explosions.

Alvarez in front of the B-29 that carried him over Japan. Image: LBNL

After the war he went back to Berkeley and built the first practical hydrogen bubble chamber, a device that would become the standard tool for particle physicists for a generation. A high speed particle would fly through the liquid inside, boiling off the hydrogen as it zipped by. The boiling liquid left a small trail of bubbles behind, photos of which could be used to figure out what had passed through. By 1968, he and his team had helped discover so many new particles with the device, he won a Nobel Prize for his work.

Photo of particle trails inside a bubble chamber.
Image: Argonne National Lab

He left working on nuclear physics and spent most of the rest of his career developing better detectors and new uses for them. In the late '60s he led a team hunting for secret rooms in the pyramids of Egypt using cosmic rays. When a high energy particle strikes a molecule of the atmosphere, it creates a shower of muons which can whizz through stone. Alvarez figured that by looking for spots that didn't seem to absorb many muons, there might lie an undiscovered room. After years of searching, he came to the conclusion that there weren't any.

Starting in the 1970s, Luis and his geologist son Walter were the first scientific team to come up with the theory that a meteorite had killed off the dinosaurs 65 million years ago. It was a hugely controversial theory at the time, but evidence kept mounting. Years after Luis's death in 1988, surveyors found evidence of exactly the kind of massive impact crater off the coast of Mexico. Team Alvarez had it right from the start.

Whistleblowing in Science

2013-06-10T15:23:00.000-04:00

Last week, the Guardian published several articles revealing an extensive, intrusive monitoring program hosted by the National Security Administration. Apparently, the NSA has required cell service provider Verizon to hand over huge troves of data covering all of its customers — data including call times, call recipients, and the length of conversations.

Edward Snowden, NSA Whistle Blower.
Image Credit: The Guardian

The source of the top-secret information remained anonymous at first but revealed himself yesterday as Edward Snowden, an IT contractor working for the NSA.

Snowden's revelations has galvanized many U.S. citizens to rally against the NSA's program, and Snowden has surely made some new enemies working for U.S. intelligence agencies. As of yesterday, Snowden's future remained uncertain while he stayed in a luxury hotel in Hong Kong.

In light of Snowden's actions, I decided to look back at two curious whistleblowing cases from the world of science: one involving a clandestine nuclear program and the other surrounding biotechnology price-fixing.

Case 1: Israel's Secret Nuclear Program

Mordechai Vanunu (center) from 2005.
Image Credit: Ali Kazak 9

Although experts suspected that Israel may have been producing nuclear weapons since the 1960's, no one knew for sure until a nuclear technician blew the whistle on Israel's secret program. To this day, Israel maintains a policy of nuclear ambiguity — neither admitting to or denying the existence of such a weapons program.

In the late 1970's and early 1980's, Mordechai Vanunu worked as a nuclear technician in Israel, but he was eventually laid off in 1985. After speaking with a freelance journalist while traveling abroad, Vanunu eventually granted an interview to a Sunday Times journalist. Vanunu detailed his experiences working on the nuclear weapons program and even provided images of the site where he worked.

Vanunu told the Times the rate at which Israel could produce refined plutonium, leading experts to believe Israel may have over 100 nuclear weapons in its arsenal.

Shortly thereafter, Israeli agents concocted a plan to retrieve Vanunu. At the time, Vanunu was on British soil, and Israel didn't want to risk damaging foreign relations by kidnapping Vanunu. Instead, they used a female agent to seduce Vanunu and convince him to vacation in Rome where he was eventually captured.

After returning to Israel, Vanunu stood trial and was convicted to 18 years in prison. He was released in 2004.

Case 2: The Informant!

Image Credit: Warner Bros

Fast forward to the 1990's for another tale of whistle blowing — this time in the world of biotechnology and food processing.

You may know about the story of Mark Whitacre from the popular 2009 film titled The Informant! Whitacre was a PhD scientist (he studied biotechnology) who worked for global food processing firm Archers Daniels Midland (ADM) in the early 1990's.

From 1992 to 1995, Whitacre acted as an FBI informant during an investigation into a global price-fixing scheme. The investigation eventually revealed that ADM had conspired with Japanese and Korean companies to fix the price of an animal feed additive called lysine.

Meanwhile, Whitacre was also embezzling millions of dollars from ADM — all while the FBI was working with him on the unrelated price-fixing case. Whitacre eventually admitted to his wrongdoing, pleaded guilty to tax fraud, and spent eight years in prison.

If you haven't seen The Informant! yet, do yourself a favor and check it out. Whitacre, who was played by Matt Damon in the movie, comes off as one of the most intriguing characters in the world of whistle blowing. That may change, however, as more is revealed about Edward Snowden.

A Post of Ice and Fire, but Mostly Fire

2013-06-07T19:41:00.000-04:00

Daenerys and her dragon. (Photo: HBO)

Sunday's Game of Thrones episode, "The Rains of Castamere," sent everyone who hadn't read the books into a tailspin. There won't be any spoilers from Sunday in this post because if the great wide internet can keep a secret for 13 years, its not going to be spoiled here. Since no one can seem to get this recent episode out of their minds, might as well add some physics. There have already been great articles about the "ice" part of A Song of Ice and Fire, but not many about the fire. Particularly the mythical Dragonfire. We learned this season that "dragon glass" can kill White Walkers. In previous seasons it was revealed that Harrenhal is in ruins because of dragonfire. How hot does dragon fire have to be? What makes dragon glass so special? Could Daenerys's dragons attack the Red Keep of Kings Landing now even though they are small?

In the book "A Song of Ice and Fire" by George R.R. Martin and the associated HBO series "A Game of Thrones," the land of Westeros was conquered by Aegon the Conquerer and his dragons long before the story starts. In one pivitol battle Aegon's dragon, Balerion the Black Dread, melted the walls of the castle of Harrenhal. Is melting stone even possible? Well, yes, it is. Pretty much anything will melt if it is exposed to enough heat. Lava is really melted stone. Though it is said that Balerion's fire was so intense it burned black, really the hottest of flames is white. Assuming his flame was in fact white hot, as all available art seems to indicate, it burns with a minimum temperature of around 2800 degrees Fahrenheit. Most castles in the UK were built with granite so assume the walls of Harrenhal in Westeros are also made of granite. The melting temperature is around 2300 degrees Fahrenheit so the walls of the castle, if exposed to continuous white flame, could actually melt. Not just crack and crumble; become liquid. Daenerys Targaryen hopes to cross the sea and again conquer the Seven Kingdoms and has her own trio of baby dragons with which she hopes to accomplish this lofty goal. Her dragons are considered very young and not yet enough of a threat to try and take the city. Frankly, they seem pretty dangerous to me. They can fly and shoot flame roughly 50 yards. But is their fire hot enough to melt the walls of the Red Keep of King's Landing? In a word, no. The flame these babies produce is only orange, not white. Deadly enough for a man, but only about 2000 degrees Fahrenheit, 800 degrees short of what would be needed for an assault on the walls. It seems that as they grow, dragons don't just develop in size, they develop in heat intensity. Cool! Or, I guess, well, deadly hot.

Dragonfire can be used to make more than just castle ruins, it can also turn sand to glass. Dragonglass seems to be obsidian made with dragonfire instead of a volcano. When lava rich in feldspar and quarts is cooled very quickly, there isn't enough time for the molecules to align neatly and form a crystal. Instead, the molecules harden in a disordered fashion and become glass. The resulting "volcano glass" is more commonly known as obsidian. This is a distinct two step process. First the rock is melted and becomes liquid and is then cooled quickly. However, in certain cases this two step process happens very quickly and it seems the glass is produced in one step. At the Trinity test site, it is not unusual to find what is called Trinitite or Trinity Glass. During the bomb test the desert sand, composed mainly of quartz and feldspare with hints of other elements, was sucked up into the bomb blasts fireball, melted and cooled rapidly as it rained down. It can be found in several colors depending on what trace elements are present, some types are even red when copper from near by electrical cables was brought into the mix. It is mildly radio active. This whole process can also happen when sand is struck by lightning. The sand melts with the heat of the lightning then solidifies into glass very quickly. It seems that there is no reason this shouldn't happen with dragonfire. Interestingly, the temperature needed to melt rock and form obsidian is very close to the temperature needed to melt granite. Seems like these dragons were made to conquer Westeros and create the weapons needed to rule Beyond the Wall. If any one of the great dragons blew fire on sand or other glass-forming compounds, the sand would melt then harden quickly into the Walker-killing glass.

Obviously there is some magic in the dragon glass that makes it deadly to White Walkers, but would it be possible for obsidian to maintain its slicing and stabbing power at temperatures low enough to crack steel? In the only scene of a White Walker being killed, he grabs a steel blade and shatters it and is then stabbed with obsidian. Is this possible? Steel is very good in normal temperatures, but becomes brittle below around -120 degrees Fahrenheit. Apparently White Walkers have an extremely low core temperature. But the Dragon Glass was unaffected by this creature's frozen body. Obsidian has often been prized for its ability to make a very sharp edge. It breaks in a regular way and when broken can create edges sharper than steel. It is even sometimes used in surgeon's scalpels. So even if it did crack on contact with the White Walker the way steel does, it would crack in a way that would make it more dangerous. The trade off is that it breaks very easily. An obsidian spear head can handle a lot of force hitting the tip, but not much force if hit from the side. Good thing Samwell stabbed the Walker straight on! If I were a Brother of the Night's Watch, I think I would have a steel sword with a back up obsidian dagger.

Personally, I swear my sword to House Targaryen. Dragons that are perfectly evolved to conquer this world and a warrior queen, how could they lose? Though knowing George R.R. Martin, now that I've said that she's gonna get it in the next episode.

Black Hole Cores May Not Be Infinitely Dense

2013-06-06T14:31:00.004-04:00

The cores of black holes may not hold points of infinite density as currently thought, but portals to elsewhere in the universe, theoretical physicists say.

Artist's concept of a supermassive black hole

Image credit: NASA/JPL-Caltech

A black hole possesses a gravitational field so powerful that not even light can escape. A black hole generally forms after a star dies in a titanic explosion known as a supernova, which crushes the remaining core into dense lumps.

A maddening enigma called a singularity -- a region of infinite density -- lies at the heart of each black hole, according to general relativity, the modern theory of gravity. The infinite nature of singularities means that space and time as we know them cease to exist there.

Scientists have long sought ways to avoid the complete breakdown of all the known laws of physics brought on by singularities. Now researchers suggest the centers of black holes may not hold singularities after all.

These new findings are based on loop quantum gravity, one of the leading theories seeking to unite quantum mechanics and general relativity into a single theory that can explain all the forces of the universe. In loop quantum gravity, the four dimensions of spacetime are composed of networks of intersecting loops — ripples of the gravitational field.

The researchers applied loop quantum gravity theory to the simplest model of black hole — a spherical, uncharged, non-rotating body known as a Schwarzschild black hole.

"We have been looking at various aspects of spherical models for several years," said researcher Jorge Pullin, a theoretical physicist at the Louisiana State University in Baton Rouge. "We like them because they are at the frontier of what is possible in loop quantum gravity today — a bit more complicated than the cosmologies that have been studied over the last decade, but not so complicated as to become intractable. An 'aha' moment was when we realized we can carry out an important simplification of the equations of the model."

Instead of a singularity, they found the center of this black hole only held a region of highly curved spacetime.

"This is a clean treatment of what happens inside a black hole, using a quantum theory of gravity," said theoretical physicist Carlo Rovelli at Aix-Marseille University in Marseille, France, who did not take part in this study. "It has long been expected that the singularities in the centers of black holes are cured by quantum gravity, and this is the conclusion that this work supports."

Theoretical physicists had previously shown that with loop quantum gravity, they could eliminate the singularity that past research suggested existed at the Big Bang. Instead of emerging from a point of infinite density, their work proposed the cosmos was born from a "Big Bounce," expanding outward after a prior universe collapsed.

"Perhaps in the future it can be shown that all singularities are removed by the theory," Pullin said.

Just as loop quantum gravity replaced the singularity at the Big Bang with a bridge to another universe, these new findings replace each singularity in black holes with "a bridge to another region in the future of our universe," Pullin said. Although prior studies also suggested black holes harbored such bridges, researchers had believed the singularities in black holes prevented any way of crossing those bridges.

"I think that this shows that loop quantum gravity is very vital and bubbling, and continues to produce exciting new results and new ideas," Rovelli said.

Pullin emphasized that they used a very simple model in this study, consisting of only highly curved spacetime without representing the actual matter found inside real black holes. The models for the study were also exactly spherically symmetrical, unlike many black holes, which spin and thus differ across their surfaces. Finally, in their model the black hole was there forever and will be there forever — in reality, black holes generally form after the collapse of stars and should one day evaporate away if they no longer have matter or energy to devour.

"Adding matter and having a black hole that evolves is what we are aiming for next," Pullin said.

Pullin and his colleague Rodolfo Gambini detailed their findings online May 23 in the journal Physical Review Letters.

-Charles Q. Choi, Inside Science News Service

Charles Q. Choi is a freelance science writer based in New York City who has written for The New York Times, Scientific American, Wired, Science, Nature, and many other news outlets.

PODCAST: Tornado Physics

2013-06-05T14:27:00.000-04:00

NOAA Photo Library, NOAA Central Library;
OAR/ERL/National Severe Storms Laboratory (NSSL)

Last week, the Oklahoma City area was hit with a tornado that claimed 18 lives, including those of two veteran storm chasers. The tornado came only a few weeks after 24 people were killed by a tornado that hit Moore, Oklahoma on May 20th. Tornados are more common in the central part of the United States than anywhere else in the world. How do these natural monsters form, and what do scientists need to know to keep people safe from them? This week on the Physics Central podcast we talk to Harold Brooks, a research meteorologist at the National Oceanic and Atmospheric Administration (NOAA) National Severe Storms Laboratory in Norman, Oklahoma. Brooks shares with us the physics behind tornado formation, the many ways that scientists try to gather data on these rare and unpredictable events, and what they hope to learn about them in the future.

Quantum Banking Comes To New York

2013-06-04T19:38:00.002-04:00

At 1:00pm on Tuesday, June 11, 2013.
20 Rockefeller Plaza, New York NY.
Basement Level.

20 Rockefeller Plaza, New York, NY
Image Credit: Brad Holt

The Quantum Bank will open for business.

The installation is the brainchild of the conceptual artist Jonathon Keats. For Keats, whose previous work includes: copyrighting his brain and auctioning futures contracts on his 6 billion neurons; a stint in extra-dimensional real estate -- in one day he sold 172 extra-dimensional Bay Area plots in the multidimensional space-time proposed by string theory; photosynthetic gastronomy that looks more like a plant watching television; and an attempt to engineer God (or, rather, something more God-like) starting with cyanobacteria and the fruit fly -- the quantum bank plays the market with the science of uncertainty.

Keats's theoretical foundation for quantum banking comes from Schrödinger's cat.

In 1935, Edwin Schrödinger proposed a thought experiment to illustrate the apparent conflict he saw in the theory quantum mechanical superposition. In his famous thought experiment, Schrödinger proposes a cat is trapped in a steel box with a vial of poison and a tiny sample of radioactive material. If an atom of radioactive material decays (a quantum mechanical process), the poison will be released and the cat dies. One could assume that if no radioactive atom decays, the cat is still alive.

The quantum theory of superposition stipulates that quantum events have definite values only when they are observed. Schrödinger argued that if at any moment it were equally probable that an atom had decayed and had not decayed, then the cat too would be in a superposition of alive and dead so long as the box remained closed.

Jonathon Keats's quantum banking extrapolates Schrödinger's cat to Schrödinger cash.

Accessed by the Quantum ATM, the Quantum Bank will open with seven billion accounts. One for every person on the planet, according to Keats. Anyone will be able to deposit any amount of any currency in the Quantum Bank.

Inside the Quantum ATM, a tiny uranium glass sphere is imbedded in a grid of seven billion boxes. Each box corresponds to one of seven billion quantum bank accounts uniquely identified by their coordinates.

When one dollar is deposited, the uranium will emit an alpha particle. The dollar is deposited into whichever box the alpha particle passes through and there is now one dollar in that account at the Quantum Bank.

However, Keats isn't planning on counting his pennies. Much like putting the cat in a metal box, Keats is encasing the ATM in metal and preventing any measurements. If no measurement is made as to which box the alpha particle passes through, the quantum regime prevails: the particle will pass through all seven billion boxes. All seven billion accounts will be credited -- in a quantum superposition of cash, and no-cash.

As Keats writes, "Anyone will be able to claim a free account, sharing as much of their wealth as they wish or simply living off others' quantum deposits."

Bam. Free money.

Of course, all withdrawals will be in quantum banknotes -- a currency that can be used anywhere, provided they are accepted.

"Crucially," Keats writes, "[the Quantum Bank] will be a paragon of ethical business. Unlike most banks which are backed by faith, the Quantum Bank will be backed by physics. And the new economy that the Quantum Bank facilitates will subsist in a quantum-economic superposition."

Though Keats's installation may not be an economy to bank on, his project provokes current ideological economic questions.

Seated in the heart of the financial industry, the Quantum Bank will be open to the public until June 14th asking those who dare deposit, what is the reality of the dollar in our post-recession bitcoin-banking world?

--- --- --- --- --- --- --- ---

Quark Twain would like to thank her colleagues at APS and Physics Central for a lovely tenure writing for the Physics Buzz Blog. For more, follow Quark Twain's tweets!

Algae Provide A Food Bank For Starving Coral

2013-06-03T10:43:00.000-04:00

Cells form crystals to store nitrogen when life gets tough.
Originally published: May 24 2013 - 4:30pm

By: Joel N. Shurkin, ISNS Contributor

Millennium Island in the South Pacific Ocean formed from a number of smaller islets built on coral reefs.
Image credit: NASA Earth Observatory

(ISNS) -- All over the world, coral reefs, the elaborate graceful structures that serve as the infrastructure of tropical sea life, are turning a deathly white, bleached of all life, mortally wounded. When reefs die, the metropolis of teeming life that surrounds them disappears.

Scientists in Europe found that the bleaching process that kills the reefs is even more complex than they thought. While they were at it, they discovered that the relatively new scientific imaging technique they used to observe the dying reefs may have applications for all kinds of other research, including cancer treatment studies. Science sometimes works that way.

Coral formations consist of a thin layer of living coral that sits atop calcium carbonate skeletons of the dead coral. Corals form structures shaped like fans, leaves, or even brains. Some build entire walls in the sea, which can stretch thousands of miles, like the Great Barrier Reef off eastern Australia.

The biodiversity of reefs makes them akin to underwater rain forests and is extremely valuable to the fishing and tourism industries of nations that are lucky enough to have coral reefs close to their shores, explained Anders Meibom, a physicist at the Ecole Polytechnique Fédérale de Lausanne in Switzerland and one of the researchers who studied the reefs.

The reefs survive because of the unique symbiotic relationship between the coral, tiny marine invertebrates with hard shells, and the multitude of algae strains growing on the coral. The algae, besides providing the coral formations with color, also provide much of the nutrients corals need to survive. To do this, the algae take carbon and nitrogen from the water. The coral, in turn, protects the algae from predators.

"Until recently there has been a big debate about how corals get nitrogen," said Meibom.

"Basically, our study and our pilot study show very clearly… that it is the algae that effectively takes up the nitrogen in seawater," said Meibom. Without algae to help the coral absorb nitrogen, they become malnourished.

Bleaching, which now affects even some of the largest and strongest reefs in the world, is the result of the rise in ocean temperatures, pollution and the increasing acidification of the ocean. Warm water has much less nutrients than cold water, so life in tropic seas is challenging. If ocean conditions get really bad, the algae eventually die and float away, leaving the reef bleached and dying, according to Christopher Langdon, a coral expert at the University of Miami, who was not involved in Meibom's research. The coral can carry on for a while, catching zooplankton on their own, but unless the environment improves, they will die, perhaps within months, Langdon said.

Switzerland is not a hotbed of coral reef research, Meibom admits, and the work reported in the May 14 issue of the journal mBio, was done in France, at the tropical aquarium and science museum in Paris and at Eilat, Israel, on the Red Sea. For the study, researchers filled a standard aquarium tank with corals and algae and five gallons of nutrient-poor seawater. They injected ammonium enriched with nitrogen-15, an uncommon form of nitrogen, as a pulse into the water. The nitrogen-15 was easy to trace and neither the algae nor the coral noticed a difference.

Then, using a 10-year-old technology called nanoscale secondary-ion spectrometry (NanoSIMS), the researchers were able to observe the molecules of nitrogen-15 as they accumulated inside the algal cells. Within 45 minutes, the NanoSIMS showed bright blue spots where the algae had taken the nitrogen and built crystals of uric acid to store it.

"They loved it," Meibom said "They soaked it up like a sponge."

The algae were creating a nutrient reservoir for the coral; something like a food bank for the coral to survive on through lean times.

Langdon said the coral study was the first time he heard about the algae storing nitrogen.

Meibom said the NanoSIMS technique was not new, but physicists like him rarely thought of using it on living tissues.

Physicists do not like to deal with tissues, he said, which they think of as "wet and gooey." Biologists are often unaware of the technology used in physics labs.

But the device, which allows scientists to watch where individual molecules go in complex living structures, could also be used to trace where medicines go in cells. For example, the technology could allow scientists to observe how chemotherapy attacks cancer cells. These kinds of observations could help drug researchers design targeted therapies that go directly to tumor cells.

"It opens a whole new sphere of science," he said.

Joel Shurkin is a freelance writer based in Baltimore. He is the author of nine books on science and the history of science, and has taught science journalism at Stanford University, UC Santa Cruz and the University of Alaska Fairbanks.

GPS 'Junk' Data Reveals Volcanic Plumes

2013-05-31T14:00:00.000-04:00

Scientists may be able to track dangerous ash-filled clouds by using information similar to the bars showing signal strength on a cell phone.

Volcanic ash plume covers the sky outside of Reykjavík, Iceland after Grímsvötn erupted in 2011.

Image credit: Flickr user Matito

The new technique analyzes the GPS’s “signal strength” -- the intensity of a GPS signal – as it attempts to cut through a volcanic plume.
The research was published online in the journal Geophysical Research Letters.

The dangerous particles within these plumes can clog an airplane’s engines and send it plummeting from the sky.

Two years ago this month, Grímsvötn, a volcano in Iceland, erupted, leaving behind a thick column of ash that led to canceled flights all over Europe for days.

The new research uses GPS data to detect these hazardous clouds as they fill the sky. Such early hazard detection could help pilots to avoid areas loaded with deadly ash.

Signal-strength data is logged in the inner workings of the GPS machines. But since it has never been useful to scientists studying how the earth moves during volcanic eruptions, the data has been ignored. In fact, most scientists don’t even upload the information to their computers.

“When I learned GPS, you were supposed to use it to measure where you are,” said Kristine Larson, professor of aerospace engineering at the University of Colorado Boulder and author of the study. “These days, I look for weird things to do with GPS.”

Larson was working with colleagues from the University of Alaska Fairbanks, who set up GPS antennae at Alaska’s Mount Redoubt to measure how terrain shifted during an eruption. Those measurements come from an array of satellites beaming down signals that indicate the exact position of a GPS antenna on earth.

Equipment on the ground automatically stores GPS data on the strength of the signals coming from those orbiting satellites. But Larson is the first to use the information to measure volcanic plumes.

Think of your cell phone, said Larson. “I always hear people talking about how many bars they have,” she said. “That’s basically what I’m using.”

She found that the plume, which was loaded with bits of volcanic ash, somehow blocked the GPS signal coming from satellites in space.

Knowing this, Larson could then track the plume in real time by observing the strength of the GPS signal in a certain area. Once the plume passed, the signal bumped back up to its normal level.

This once-overlooked information may help track plumes when other methods like radar or pictures taken from satellites fall short.

Images taken from space can monitor plumes but “if it’s cloudy you can’t see anything,” said Larson.

Since the GPS signal strength beamed down from orbiting satellites is largely unaffected by clouds and water vapor, Larson can detect only the dangerous ash within a plume.

Radar can spot plumes but the equipment is expensive. “We have many more volcanoes in the world than we have resources to monitor them,” said Larson. “The beauty of GPS is it’s so inexpensive.”

Many scientists already have GPS antennae dispatched at volcanoes all over the world that automatically collect signal strength data.

More research is needed to determine how dense a plume must be to cause a drop in signal strength, said Michael Lisowski, a geophysicist at the U.S. Geological Survey Cascades Volcano Observatory, in Vancouver, Wash.

Signal strength can only be measured if satellites are actively sending signals to the antennae on the ground. Since only about a couple of dozen GPS satellites are in orbit over the earth, there may be times when there is no satellite overhead to connect with an antenna on the ground and no data can be collected on signal strength.

But many countries already have plans to send new GPS satellites into space. “As more satellites systems get launched, it will become a better tool,” said Lisowski.

Larson’s study looked only at two volcanic plumes in Alaska. Plans are in place to test the technique on more volcanoes, she said. “GPS is not the only instrument that is helpful but it’s a new thing that we could add to the list of tools we’re using to make air travel safer.”

-Ryder Diaz, Inside Science News Service

Ryder Diaz is a science writer based in Santa Cruz, Calif.

The Future of Deep Space Travel is RAD

2013-05-30T17:48:00.004-04:00

In the hour of descent as the Mars Space Laboratory dropped toward martian soil a small gadget whirred. The gadget was a particle catcher.

Mars Science Laboratory approaching the martian atmosphere (artist's concept)
Image Credit: NASA/JPL-Caltech

The size of a coffee pot, NASA's Radiation Assessment Detector (RAD) hitched a ride on the Mars Space Laboratory to measure the radiation of the martian atmosphere. RAD is the first instrument to measure the radiation on the way to Mars from inside a spacecraft that is similar to one future human astronauts could fly to Mars. The results will be published in the May 31 issue of the journal Science. Today, four members of the research teams reported the results at NASA's press conference in Washington, D.C.

It's in the journey -- and in the destination

Radiation Assessment Detector
for Mars Science Laboratory
Image Credit: NASA/JPL-Caltech/SwRI

"We realized, that taking measurements on the way to Mars would be not so different from the environment the future human astronaut might experience on their spacecraft on their way to Mars." said RAD principal investigator Donald Hassler from the Southwest Research Institute.

The researchers turned RAD on about ten days after the Mars Space Laboratory launched in November, 2011 and collected data about the radiation environment inside the space capsule for seven months.

"NASA is planning on sending astronauts to Mars in the 2030's," said Chris Moore, the deputy director of advanced exploration systems at NASA headquarters, "Before we can send astronauts there, we need to understand the environments and hazards they would face. RAD data will help us design the space habitats in which astronauts will live on their trip to Mars."

There are two types of deep space radiation the RAD system measures: galactic cosmic rays and solar energetic particles. Galactic cosmic rays come from outside the solar system and are thought to originate at supernova remnants and other high-energy explosions. Despite their high energy, they radiate at moderately low levels that vary over the eleven-year solar cycle. In contrast, solar energetic particles during solar storms and coronal mass ejections are very difficult to predict and can last anywhere from hours to days. While spacecrafts do a pretty good job of keeping solar energetic particles out, we don't yet know how to prevent cosmic rays from penetrating the ship's living quarters.

Radiation exposure comparison from Mars trip
Image Credit: NASA/JPL-Caltech/SwRI

Radiation exposure during deep space missions remains an outstanding health concern for astronauts. The RAD measured that the Curiosity rover was exposed to 1.8 milliSieverts per day of radiation from galactic cosmic rays, during its seven month journey to Mars. Only about five percent of Curiosity's radiation exposure came from solar particles, thanks to a calm solar cycle and shielding from the spacecraft.

"In terms of accumulated dose, it's like getting a whole-body CT scan once every five or six days," said Cary Zeitlin, lead author and principal scientist at the Southwest Research Institute in NASA's statement.

Based on the new RAD data, engineers at NASA hope to design more effective shielding for future deep space flight. "The radiation environment in deep space is several hundred times more intense than on earth," said Zeitlin, "that's even inside a shielded spacecraft."

Dressing for Mars

There are basically two ways to protect astronauts from radiation, according to Moore.

"Hydrogen is the best radiation shield we know about", said Moore. One way to protect a crew would be to surround their living quarters with walls filled with water. Water, which is rich in hydrogen, absorbs the radiation. Moore said that NASA is also tossing around the idea of arranging food packets around the spacecraft living quarters; food, rich in water, also contains a lot of hydrogen.

Currently, NASA uses polyethylene, a material made up of long chains of hydrogen. "Some of our initial concepts [for new space suits] involve multiple layers of polyethylene plastic," Moore said, "I tried on one of these garments once. It reminds me of samurai armor. Or a very heavy coat."

In 2015, NASA is launching a version of RAD to the International Space Station. With comparable instruments on the ISS and on Mars, researchers will be able to compare radiation levels, calculate health risks, and develop new tools for the future of deep space travel.

Podcast: SESAME

2013-05-29T11:49:00.002-04:00

On this week's podcast, I talked to Herman Winick of SLAC, who's been helping build a Synchrotron light source in Jordan, the first one in the Middle East. He said that there are more than 60 synchrotrons around the world operating right now. These machines generate bright flashes of intense X-ray light for all kinds of scientists to use to use to look at things as small as a molecule. They're tremendously versatile tools for researchers to study everything from the structure of proteins to the manufacture of microelectronics.

This schematic of France's Synchrotron Soleil gives a good idea of what the completed SESAME synchrotron might look like. Image: EPSIM 3D/JF Santarelli, Synchrotron Soleil.

Their economic significance is just as important to a country as their scientific value. These machines are big and expensive, so countries can usually only build them once they reach a level of economic development. They draw a lot of power so they need reliable electricity and their upkeep requires a certain level of technical expertise.

Building a synchrotron light source is usually a good investment for a country in the long run. They help stem the age old "Brain Drain" problem facing many developing nations. If a scientist's research reaches the limit of their home country's capabilities, they'll travel abroad to continue their work and oftentimes never come back. Many developing nations have seen generations of their best and brightest migrate away this way. Having a synchrotron in the country is like an anchor, letting the researchers do what they need to do in their home nation.

China's economy has been booming in recent years and in 2009 it announced it would be building it's own "world class" synchrotron. In the 1980s Brazil, South Korea and Taiwan also built their own facilities when their economy and infrastructure could support it. It's almost like a badge of honor when a country reaches the point it can support one.

SESAME in Jordan is a little different because instead of being built by one single country, nine are pitching together to build it. Each is giving what it can, and the rest of the world has donated money and parts to get it off the ground. It'll be a major milestone for the region to come together and complete a major project like that.

There's still a lot of room in the world for more synchrotron light. There's still no such facility on the entire continent of Africa. In Early May, the government of South Africa joined the ESRF accelerator consortium located in the south of France. Scientists from South Africa will be able to travel to the science facility and access its beam lines. Scientists in the country have been pushing for a synchrotron of their own, and this is an important step towards building up their capability.

Calling All Aliens: One Man's Search for Romance

2013-05-28T17:49:00.002-04:00

"While extraterrestrial civilizations may be rare," Peter Backus wrote in 2010, "there is something that is seemingly rarer still: a girlfriend. For me."

Backus's paper, in which he humorously applies the Drake equation to his dating prospects.

For Backus, dating and alien civilizations had a thing or two in common. "The idea occurred to me," Backus said in an interview with Today, "that you could do the same thing with any population."

Backtrack to Green Bank, WV in 1961, on the eve of the search for extraterrestrial intelligence (SETI), when astronomer Francis Drake came up with a ballpark estimate of the number of communicative alien civilizations in the Milky Way Galaxy.

The so-called Drake Equation estimates the number (N) of possible intelligent alien civilizations (one civilization per planet) in the galaxy by multiplying together quantities like the number of stars that are like our sun and the rate of star formation (R), the percentage of these stars that also form planets (f_p) and fraction of those planets that are earth-like (i.e. possibly inhabitable, n_e).

If you think the odds are getting slim, factor in the odds that an earth-like planet actually develops life forms (f_l), and that this life form develops the sort of intelligence (f_i) that would enable it to develop methods of interstellar communication, like radio and lasers (f_c). Drake's equation also includes the average lifetime (L) that such a civilization would have communication technology.

Astronomers estimate that there are on the order of 300 billion stars in the Milky Way Galaxy. Drake's rough (high) estimate came out to about N = 10,000 possible civilized, intelligent, radio-wielding, laser-shooting civilizations -- about 0.000003% of our stars.

Like the Howards before him, Backus applied this apt comparison to his chances of finding a match in the dating pool.

In his paper, Backus mapped Drake's variables to the civilization with whom he hoped to communicate. In the search for the number of potential girlfriends (N), Backus factored in the population growth in the UK, the fraction of whom are women who live in London, education backgrounds, attractiveness, and age. This pool left him at about 14% of Londoners, or about 10,500 people. Smartly, he also included an estimate of the percent of these women who would be interested in him.

The result: 26. With a 1 in 285,000 chance of finding a girlfriend, Backus writes that his odds were about 100 times better than the chance we'll communicate with an alien civilization.

Turns out, it's also a great pick up line. Backus reports he is getting married this weekend -- despite all odds.

Sounds Of The Sea: Stones Clanging

2013-05-28T10:57:00.005-04:00

Tide-borne pebbles on the seabed can drown out other ocean noises.

Originally published: May 21 2013 - 10:00am

By: Joel N. Shurkin, ISNS Contributor

(ISNS) -- The oceans are very noisy places: Shrimp crackle, fish bark, dolphins click, humpbacks sing, and many species talk to each other. Humans steer loud ships through the waters.

According to research by a graduate student at the University of Washington, even the gravelly seabed contributes to the cacophony, particularly when the tide is strong. Indeed, the noise of the gravel can be so loud it often drowns out the other noises, making it impossible for scientists to hear the other sounds of the sea if the animal is not close to the microphone.

A still capture from "Dynamic Earth: Exploring Earth's Climate Engine," showing an underwater view of ocean currents at different depths off the continental shelf of North America. The full video can be seen here: youtu.be/ujBi9Ba8hqs

Since there is increasing interest in harnessing the currents and tides for energy, scientists need to know as much about the environment as they can, and the noise was getting in their way.

"The reason for my project is that scientists are starting to look at these environments to exploit the power of these currents for renewable energy generation," said Christopher Bassett, a doctoral student in mechanical engineering. "Studying the sound is one way of addressing the potential for tidal energy development."

Studying the sound also may make it possible to learn more about the material on the seabed.

Bassett's research is published in the Journal of Geophysical Research: Oceans.

In some parts of the world, such as in Canada's Maritime Provinces, the tides are so strong they would make superb renewable sources of energy if that energy could be captured.

Bassett and two colleagues lowered acoustic monitoring equipment into the Admiralty Inlet, which connects Puget Sound with the Strait of Juan de Fuca, the gateway to the Port of Seattle to the south. All the tidal flow runs through it, sometimes as fast as 8 mph. The site is less than half a mile from the shipping lane.

The seabed, almost 200 feet down, is relatively flat, made up of pebbles and cobbles, a quarter of an inch to as large as four inches across. There is very little sand, Bassett said, because the strong current flushes it away.

It is the clacking of the pebbles against each other when the current moves them that produces the noise. The whole seabed isn't making noise, just sections here and there.

Bassett says his study is the first to show that currents are capable of regularly moving round objects that large.

The noise doesn't sound like pebbles crashing together. Rather, it is more like a rushing clamor, although occasionally it sounds like the noise made when someone dumps a stream of gravel on a pile of similar stones, Bassett said.

Bassett and his colleagues found the sound made by the shifting stones was at the same frequencies as the sounds made by orcas communicating with each other, in the range of 2 to 40 kilohertz, extending well into the ultrasound, above the range that humans can hear. The stones limit scientists' ability to detect most of the orcas' sounds, and the orcas can't hear each other if they are near the stones.

"By almost every objective standard, it is a noisy place," Bassett said.

Many stones are covered with biological matter, such as algae and sponges. It is likely the stones that are not covered are the ones that move around the most because the collisions would knock off the covering.

The study is valuable especially if engineers go ahead and try to harness the tides for power, said Lindy Weilgart, a marine biologist at Dalhousie University in Halifax, Nova Scotia. One of the prime sites for such projects would be the Bay of Fundy, between the Canadian provinces of Nova Scotia and New Brunswick, which has the highest tides in the world.

Turbines used to generate the power are "like blenders," she said, and would pose a lethal threat to marine mammals in the area. The turbines make enough noise to scare the mammals away, but if the seabed is drowning out the turbine noise, the animals might be vulnerable.

"I didn't realize the extent of the problem," said Weilgart, whose specialty is the vocal behavior of whales. Having the seabed as a source of loud noise would make her research more difficult.

"You have to worry about taking noise into consideration because it is predictable enough; you ought to be able to model that. It's a manageable problem," said Weilgart. "But if it swamps all the other noise you are not getting a reliable picture."

Joel Shurkin is a freelance writer based in Baltimore. He is the author of nine books on science and the history of science, and has taught science journalism at Stanford University, UC Santa Cruz and the University of Alaska Fairbanks

A Smartphone App for the Living World

2013-05-24T20:56:00.002-04:00

Imagine holding your smartphone up to the sky and detecting pollen in the air or bacteria in the water. It's like SpectraSnapp for the living world.

University of Illinois at Urbana-Champaign researchers developed the handheld hardware and smartphone app that transforms the camera and computing capabilities of the iPhone into a sensitive biosensor. The researchers envision scientists, physicians, or even backpackers will be able to use the App, the iPhone GPS software, and holder for in situ air pollution analysis, to find clean groundwater, or to inexpensively and quickly detect toxins, viruses and bacteria at field clinics. The research was published on April 3, 2014 in the journal Lab on a Chip.

Smartphone Biosensor Demonstration / University of Illinois Urbana-Champaign News

The crux of the work lies in the powerful combination of spectroscopy hardware and app software development.

The hardware holds the optical components not found in ordinary smartphones. Released from the binds of optics tables in dark labs, the handheld cradle aligns the lenses and filters with the smartphone's camera.

The secret players in the hardware are specially prepared microscope slides and a photonic crystal that can be designed to reflect one color of light, and allows all the others to pass through. Using different microscope slides prepared react to different biological agents, the researchers coat the slides with a photonic crystal. If a biological agent attaches to the surface of the photonic crystal, the color of light reflected off of the slide will shift towards the red.

To test for a specific biological agent, like E. coli on a spinach packaging plant, the user would slip an "Test-for-E. coli" slide into the cradle and compare the light spectrum when the smartphone is pointed at the spinach to the control spectrum. The degree to which the color of reflected light shifts (which appears as the movement of the black bar in the light spectrum) indicates the amount of E.coli is in the sample.

In the paper, the team tested their design by detecting immune system protein. In theory, the microscope slide could be prepared to detect any biological molecule or cell. The cradle holds only about $200 of optical equipment but provides data comparable with laboratory spectrophotometers hundreds of times the cost. The researchers hope the device will prove effective for on-location analysis in developing countries and hope to make the hardware cradles available next year.

Scientific Ruins: The Defunct Atom Smasher Next Door

2013-05-23T16:25:00.000-04:00

There's a derelict atom smasher nestled in the middle of suburban Washington DC. The old Atomic Physics Observatory sits in the middle of the Carnegie Institution's Department of Terrestrial Magnetism, a scientific research campus in the city's Chevy Chase neighborhood.

The APO was named and likewise designed to look like an astronomical observatory, in hopes that the nearby residents wouldn't put up too much of a fuss when the Department of Terrestrial Magnetism built a particle accelerator in the well-off suburb.

When it was built in 1938, it was one of the most powerful particle accelerators in the the world. Less than a year after it was first turned on, it played an important role in confirming the nuclear fission of uranium, the discovery that directly lead to the atomic bomb. Today, it's mostly used to store garden tools. The maintenance staff let us look around at what's left of the old machine.

Walking in through the front door, one's vision is almost entirely taken up by the gigantic, upside-down pear-shaped pressure tank taking up most of the building. Inside is the accelerator. It's a Van de Graaff accelerator, very different than most accelerators used today. It uses static electricity to shoot ions down a beam pipe to a target room below.

At its widest point, the tank is 37.5 feet across and pressurized up to 50 psi of compressed air. The tank was built by Chicago Bridge and Iron Works who specialized in building tanks for natural gas. Its hermetic seal kept the humid DC summers from shorting out the static electricity generator inside, and the high pressure helped it store tremendous charge.

We wanted to take a peek inside of the tank but the only hatch leading inside looks like it hasn't been opened in ages.

This cutaway of the accelerator shows what we were missing. Inside there's a flattened steel sphere sitting on top of of four 26-foot-tall posts. A moving conveyer belt carried away electrons from the suspended spheroid, giving it a strong positive charge. Inside, a small filament emitted positive ions at the end of a long pipe leading straight down. The ions each had one proton and one neutron. The positive charge of the steel dome repelled the positively charged protons, shooting it and the neutron it was attached to down the pipe at incredible speeds. Magnets guided and focused the beam of ions. Near the end, the positive protons would be sheared off, leaving only a stream of neutrons behind. (Carnegie Institution)

These guys didn't seem to have any problems opening up the hatch. (Carnegie Institution)

This old photo taken from inside of the tank looking up shows the spheroid while its being installed back in the '30s. Notice the beam pipe isn't in place yet. (Carnegie Institution)

Underneath the pressure tank is a space where scientists could access different controls and measuring equipment. On the far right is the beam pipe as it exits out of the pressure tank and leads into the target room below. There's all kind of old equipment and gauges that haven't been used since the facility was shuttered in the 1970s.

A ladder leads down to the target room. It looked pretty rickety, so we opted to take the tunnel from the building next door.

The concrete hallway zig-zags to prevent dangerous X-rays from escaping from the target room.

The results of decades-old experiments are still tacked up on bulletin boards. The "Notice to Employees" about radiation protection bears the seal of the old Atomic Energy Commission, which ceased to exist in 1975.

One room off to the side looks like it used to hold spare parts for the machine. Now it seems to be a catch-all for all kinds of old equipment from around the lab.

Two wooden doors lead to the target chamber. Along the walls are notes written in pencil of when the he ion source was last refilled with deuterium.

High energy neutrons cascaded down through the beam pipe from the accelerator above. The tube would have continued down onto a table where researchers could irradiate whatever samples they needed to.

Now, most of the space is stacked floor to ceiling with derelict equipment. Over the years the laboratory has done research on Earth's magnetic fields, seismology, astronomy and nuclear physics. There's probably a bit of everything in here somewhere.

The APO played a central role at a pivotal moment in 20th century physics history. In January of 1939, Niels Bohr arrived in the United States with important news. Just a few weeks earlier, Otto Hahn, Fritz Strassmann and Lise Meitner in Germany discovered that when they bombarded uranium samples with neutrons the atoms split apart into two atoms of barium, releasing tremendous energy in the process. They had discovered nuclear fission.

Bohr broke the news of the discovery at a physics conference in downtown Washington DC. Two physicists sitting in the back of the room, Richard Roberts and Lawrence Hafstad, shot each other excited glances and bolted across town. They fired up the APO and within 48 hours, had replicated the experiment using their new particle accelerator.

Attendees of the conference showed up to see the results and brought along a reporter. Within a day, the world learned about the imminent arrival of atomic energy. The physicists snapped a photo inside the target room just after the demonstration of fission. From left to right Robert Meyer, Merle Tuve (who designed and built the APO), Enrico Fermi, Roberts, Leon Rosenfeld, Erik Bohr, Niels Bohr, Gregory Breit and John Fleming. Edward Teller was still upstairs when the photo was snapped. (Carnegie Institution)

The APO wasn't used at all during World War II. Just about all nuclear research was classified and focused on building the atomic bomb in New Mexico. The Department of Terrestrial Magnetism devoted itself to designing the proximity fuze for rockets instead.

After the war, research at the APO started up again, studying the nuclear structure of hundreds of atomic isotopes. In the 1960s scientists updated the machine to fire polarized protons, investigating the structure of unstable, short-lived nuclei. In 1975, the machine had finally outlived its usefulness, and was deactivated for good.

I couldn't help but wonder what would it would have been like to see the old machine active. Turns out, in 2010 nonfiction artist Jim Sanborn rebuilt an earlier prototype of the APO for an art installation in Denver. He scoured through old blueprints and schematics he found in the Carnegie archive, and built an exact working replica of the machine. Then, like Roberts and Hafstad, he used it to fission uranium of his own.

PODCAST: The Physics of NASCAR

2013-05-22T16:24:00.003-04:00

This week on the podcast I chat with Diandra Leslie-Pelecky, a physicist at West Virginia University and the author of The Physics of NASCAR. What on earth does NASCAR have to do with physics? Everything. From the banking of the turns to the design of the rear-view mirrors, physics is what makes NASCAR possible.

And NASCAR has also proved to be a laboratory for new physics insights. Take the phenomenon of drafting, in which one car driving behind another can get a boost in speed from the front car's wake. Cyclists take advantage of this, as do birds. Drivers and team members spotted the change immediately, although they couldn't explain exactly why it was happening (and the exact explanation was left up to physicists to figure out). They started testing this phenomenon in practice, and worked out how they could use it to their benefit during races. This practice of observation and testing is also the basis of the scientific method.

To hear more about the physics of NASCAR, listen in to this week's podcast. You can also hear Diandra on the radio show SiriusXM Speedway, where she appears regularly to help debunk myths about the science of NASCAR (like whether or not the cars speed up when they go from the track to the grass).

What Stresses Gorilla Glass Makes It Stronger

2013-05-22T10:20:00.001-04:00

Theory tackles how glass remembers earlier forces.

Alterations to the usual glass production process, such as putting the material under stress, can introduce effects that linger even after the material hardens. While manufacturers have long exploited this phenomenon to strengthen glass, a new theory aims to get closer to understanding why it happens.

Glass is not as well understood as most materials, because it straddles the line between liquid and solid. In typical crystalline materials, molecules assemble into a set structure over the span of the entire material as the substance solidifies from a disordered liquid form. Glass, on the other hand, retains a liquid-like disorder even after it hardens.

Without a set architecture, these disordered molecules are particularly vulnerable to outside forces. If you push or pull on a substance, you create internal forces, or stress, in the material itself. Once you remove that force, you'd expect the molecules to return to equilibrium, removing the stresses. But glassy materials "remember" the long-gone force.

Physicists are trying to understand how glass molecules permanently retain this residual stress. "The material properties depend on how the material is produced," said Thomas Voigtmann, a physicist at the University of Konstanz and the Institute of Materials Physics in Space, in Koln, Germany. "And that's a rather fascinating topic to understand."

In a paper accepted for publication in Physical Review Letters, Voigtmann and his coauthors describe glass's residual stress in physics terms, by observing how the motion of individual atoms affects the entire complex system. But engineers are already taking advantage of glass's history dependence—no theoretical physics required.

Stress helps glass resist damage. By incorporating it into the manufacturing process, Engineers at Corning, Inc., in N.Y., can give a normally fragile material super-strength. Their Gorilla Glass product now forms the screens of more than 1,000 different devices, from smartphones to tablets to televisions.

To avoid building flaws into the material, Corning creates large, flat panes of Gorilla Glass mechanically. During the process, the molten glass is suspended by its top edge, leaving it untouched by human hands—or anything else. Despite their stability, these sheets cannot prevent future damage...yet. The next step is to apply stress to the glass, compressing its molecules to strengthen the material and enable it to resist flaws.

Cut to appropriate sizes, the unfinished Gorilla Glass then takes a bath in a molten solution of potassium salts. This process leaches small sodium ions out of the glass and replaces them with larger potassium ions. The large particles squeeze the sheet from the outside in, compressing the material. This creates two outer layers squeezing inwards, towards a central layer that balances out the internal forces by pushing back.

"You have an equilibrium of stress and tension," explained Marcus Haynes, a senior applications engineer at Corning. "There's a layer of compressive stress, then a layer of central tension, where the glass wants to press out, then another layer of compressive stress."

Compressing the surface of the glass makes it stronger, able to resist blows and scratches rather than breaking immediately.

"Even if you damage the glass, the flaw is contained within that compressive stress layer," Haynes elaborated. "It doesn't allow the flaw to expand." In order to break a Gorilla Glass screen, a flaw would have to penetrate through the compressive layer and into the tension layer.

Although the ingredients that go into Gorilla Glass also help the material withstand damage, stress is the real key to its abilities. It works even though its creators didn't understand its exact molecular behavior. But scientists still want to know more.

"We're trying to give some guidance on why this works and how it can be improved — that's the long term goal," said Voigtmann. "What we're trying to do is give a theoretical physics explanation for empirical laws."

To formulate this explanation, the scientists used both theoretical physics and experimentation. Molecular interactions are particularly difficult to observe because they occur on such a small scale. Instead of zooming in to the molecular level, the researchers took advantage of a glass substitute: colloids. A colloid is a type of substance with particles suspended in a solution. The common colloid paint, for example, consists of solid pigments floating in liquid.

"These colloids act like atoms," explained Voigtmann. "It's a model system that in many respects behaves like window glass, but it's on a blown-up scale: colloids are big enough to watch under a microscope."

The researchers put colloids under stress and then observed their behavior through a microscope. This led them to develop a physical theory that describes why forces in molten glass remain locked in the material.

Although this theory accurately models the behaviors that the researchers observed during experiments, the understanding of glass remains a "hotly debated" topic, said Voigtmann.

- Sophie Bushwick, Inside Science News Service

Sophie Bushwick is a freelance science writer based in New York City. Her work has appeared in numerous print and online outlets.

How to Sell a Particle Accelerator: Positron-Electron Love Explosions

2013-05-20T13:39:00.002-04:00

While the discoveries and excitement surrounding the LHC have started to cool down, a new contender in particle physics is emerging. Over 2000 scientists are currently working on one of two competing particle accelerator proposals: the International Linear Collider (ILC) and the Compact Linear Collider (CLiC). Both projects would smash electrons and their antimatter counterparts — positrons — at speeds nearing the speed of light. The LHC, on the other hand, primarily smashes heavier particles together including protons and lead nuclei.

Several countries aim to host one of these international physics collaborations, and two regions in Japan have created marketing videos to garner support for a future ILC site. With the same goal in mind, both regions took radically different approaches to their video projects.

Below you can see the more popular video created jointly by the Saga and Fukuoka prefectures. The video combines anime, lab coat raps, and a burgeoning friendship that culminates in a positron-electron collision of love as symbolized by two Japanese girls. At least, I think that's what happened.

Be sure to turn on the English subtitles for the full story.

Another group from the Tohoku Conference for the promotion of the ILC took a more conservative approach in the video below.

ILC Facts

The proposed ILC would run over 30 kilometers long, a bit longer than the LHC's 27 kilometer circumference. This new collider would accelerate particles in a straight line unlike the LHC, which accelerates particles in a circular beam path that sits under the Swiss and French countryside.

Synchotrons like the LHC have several advantages over linear colliders (e.g. the one at Stanford's SLAC National Accelerator Laboratory). Most notably, particles in synchotrons speed up during multiple trips around the ring, adding more energy than a single trip down a straight path.

Linear colliders have their own benefits, however. They don't require the complex kinds of magnets that keep particles in a circular path — magnets that presented a few troubles during the development of the LHC. Also, linear colliders lead to far less synchotron radiation — a form of energy loss that happens when particles accelerate in a curved path. This radiation limits the speeds and energies of colliding particles, especially smaller, nimbler particles like electrons.

Despite the design differences, scientists behind the ILC project hope to complement and expand upon the science going on at the LHC. High energy electron-positron collisions could reveal more about conditions during the Big Bang, dark matter, and dark energy — the pervasive, invisible energy thought to contribute significantly to the expansion of the universe. Detectors at the LHC hope to reveal similar secrets from the early universe.

But the Saga and Fukuoka prefecture team behind the first video understands that there's more to the project than cold, hard physics. There's a human element to such a large collaboration, and they've definitely tapped into that in a wildly entertaining way.

H/T ILC Newsline

A Carbon Signature Revealed

2013-05-18T04:25:00.001-04:00

Imagine diving into the placid surface of a painting by Vermeer, parsing apart Klimt's bejeweled surfaces, or untangling Jackson Pollock's knots of paint. Art historians, collectors, and restoration scholars have long sought to uncover the methods of great painters.

Over the past decade, scientists have peered with light beneath the varnished surface of paintings to discover the chemistry of pigments, to identify the authors of unsigned works, or probe the crack depths from damage or age.

Now, researchers at the University of Barcelona in Spain have used light at terahertz frequencies to uncover the hidden carbon signature of a painting previously thought to be unsigned. Though unsigned, the painting has been studied by art historians and confirmed to be painted by the Spanish artist Goya in 1771. Such secondary validation made the piece an apropos choice by the researchers, who published their findings May 14, 2013 on the arXiv.

"Sacrifice to Vesta" at three different levels of imaging at visible and THz frequencies.
Image Credit: http://arxiv.org/abs/1305.3101

Nested between the infrared and microwave regimes, terahertz radiation can travel through materials like plastic or canvas and bounces back slightly differently depending on the chemical composition of each paint color.

To analyze the Goya piece, the researchers parsed the painting into 1 millimeter squares and recorded the reflected terahertz wave from each square, obtaining images with millimeter resolution. To analyze the structure of the painting -- essentially how the paint was laid on the canvas -- the researchers looked at the shape of the reflected wave. At each layer of paint, the reflected wave registered a unique bump. This kind of so-called structural data enabled the team to reveal features of the painting hidden beneath layers of paint.

Through the structural analysis, the scientists found new textures beneath the painting's veneer. They were able to uncover the thickness of paint strokes, the order of the layers of paint, and even wrinkles in the canvas from pigment deterioration, or mechanical tension on the canvas.

Then, at the very bottom of the painting, the team found a signature. Blind to the visible eye, to X-ray, and to infrared analysis, the researchers identified what they believed to be Goya's signature in the image created by the terahertz reflections. The researchers report that the signature was likely written with a pencil. They suggest that, over the years, the top coat of varnish darkened and obscured the carbon signature. They write that the signature might be missing in 2007 X-ray studies of the painting because carbon has a very similar atomic weight to that of the canvas and paint pigments, leaving the X-ray imaging unable to distinguish between the materials.

Identifying chemical compositions of paint pigments and other paint media remains an area the researchers hope to explore. In their study, the team found that some pigments reflected terahertz waves more than others. They speculated that these have a higher metallic content leading to higher reflectivity. In the future, the researchers imagine that the creation of a pigment spectroscopy database could enable artists, restorationists, and historians to study the detailed chemical compositions of paintings.

Mosh Pit Mechanics, Chattering Gazelles, and Bouncing Baby Shampoo

2013-05-16T15:09:00.000-04:00

Physics Phun in the Phorthcoming Physical Review

What do gabby gazelles, mosh pits and jumping shampoo jets have in common? They're all covered in upcoming Physical Review papers. (This image is a mash up of pictures from Wikimedia Commons. Details and rights info are here, here and here.)

Week after week, the American Physical Society journals are chock full of some of the most important physics papers published anywhere. Importance, of course, doesn't necessarily make something interesting to anyone outside the field. Every once in a while, though, we get a handful of papers that are significant enough to get into the Physical Review journals, including the flagship Physical Review Letters, as well as appealing to people who don't necessarily spend their days hunkered down in a lab or scribbling away on an equation-covered blackboard.

After a quick glance at papers currently accepted for eventual publication in the Physical Review, I've found three that I can't wait to read. Topping my list is a look at the surprisingly simply collective motions that take place in mosh pits. In case you've never been in one, a mosh pit is usually an area near the stage during a concert where the most rabid fans can enjoy the show while being slammed around by dozens of other equally rabid fans. We covered this very research before, when it was being presented at the 2013 APS annual meeting in Baltimore, and it's worth checking out our older piece if you want to see how a crowd of crazy kids is like a flock of birds or a swirling gas. The interesting thing to me is that many people I spoke to back in March thought the research was nothing but a frivolous distraction for a few grad students who really should have been concentrating on their dissertations, not hanging out with hoards of death metal moshers. With the study soon to appear in the world's greatest physics journal, I wonder who's laughing now?

I'm nearly as eager to read about a simulation of Mongolian Gazelles as they wander the steppes of Eastern Mongolia in search of food and, apparently, hollering to each other to "Come and get it!" I had never heard of Mongolian Gazelles before, and hadn't realized that gazelles of any type made noises, much less called other gazelles to dinner. That means that in simply reading one abstract, I've already learned three entirely new things! I can't wait to see the actual paper to find out what other gazelle-related wonders it may contain.

The third forthcoming paper I stumbled across had me worried for a bit. It seems that shampoo can sometimes leap out of your hand as you're pouring it from the bottle in preparation to wash your hair. It's not something I've ever experienced, although it makes my eyes water in anticipation of an unprovoked shampoo attack the next time I take a shower. While it's new to me, I've learned that the phenomenon is well known, and is called the Kaye effect. Check out the video below for some eye-endangering examples.

The new twist, in the paper soon to be published in Physical Review E, is that these jets of soap don't occur for the reason usually given. In the past, most people who studied the effect assumed it had something to do with the fact that shampoo doesn't flow like normal (so-called Newtonian) fluids. Not so, it turns out. As the researchers say in their abstract, " . . . we show unambiguously that the jet slides on a lubricating air layer."

Now that we know the truth, I can only assume that a solution (other than wearing protective goggles to bathe, as I plan to do tomorrow) can't be far behind. One possibility that comes to mind, assuming they're right about the lubricating air, is to shower in an evacuated vacuum chamber. No air, obviously, means no bouncing soap jets. NASA could probably work that out with some sort of pressure suit arrangement. Getting access to your hair through the helmet is going to be tough. But hey, they put a man on the moon, and are currently working on at least one impossible science project and another nearly impossible one - and showering isn't exactly rocket surgery.

PODCAST: Red Rover

2013-05-15T17:12:00.001-04:00

Basic Books

This week on the Physics Central podcast we're talking about an awesome new book called Red Rover: Robotic Space Exploration from Genesis to the Mars Rover. The book's author Roger Wiens talks with us about his career working on robots that are sent to explore space.

Wiens worked on the Genesis space mission, which launched back in 2001, and he is the principle investigator on the ChemCam instrument aboard the Curiosity Rover. In his new book he talks about the ups and downs and successes and failures that come with trying to design and build these instruments, not to mention navigating political hurdles and the curve balls that life throws at all of us. I love that Wiens isn't a dramatic kind of guy—he really loves the science—but a story like this one can't help but be full of drama.

But in case you're more one for the science, let me tell you a little about the projects Wiens has worked on.

Genesis caused a media splash when it crash landed in the Utah desert in 2004. The mission spent 3 years out beyond the orbit of the moon, where it collected samples of the solar wind, and then brought those samples back to earth (it was the first instrument to travel that far from home and then return).

The solar wind is a bit of a living fossil: it's believed to contain the same mixture of elements that existed in the pre-planet days of our solar system. Scientists had previously believed that the sun's elemental mixture would match that of the Earth—since the two came from the same dust cloud.

But Genesis told a different story. The oxygen on Earth is over 99% oxygen 16. That's an isotope of oxygen; which you can think of as a different flavor. There are hints of oxygen 17 and 18 as well. And the particles that Genesis collected from the solar wind contained more oxygen 16 than Earth. Which means at some point in our planet's history, it acquired a higher concentration of heavy oxygen elements. Those things don't just pop into existence: a chemical or physical process has to take place to make the change. So what happened to the Earth that made this possible? That's still a largely unanswered question, but thanks to Genesis, scientists are one step closer to finding the answer.

And then there's ChemCam. Science-fiction-come-to-life-ChemCam. This instrument shoots a laser beam at rocks on Mars and can quickly tell scientists what those rocks are made of. The scientists then decide which rocks they want to study more.

The laser beam is cheap to power—it only requires a few watts. It is only the size of a pinhead, and it only lasts for 5 billionths of a second. But, within that small area and short time frame, it packs in the energy of over a million light bulbs. The laser beam hits another material and gives it such an energy punch that it radiate. A telescope on board the rover catches the light, which is like a fingerprint, revealing the make-up of the material that ChemCam just blasted.

At the end of our chat, Wiens read a section of his book that mentions all of the robotic missions that are currently exploring our solar system. I wasn't aware of all of these, and I've had a great time learning about them since. I hope you do as well.

"Mechanical creations from Earth are orbiting Mercury, Venus, the Moon, Mars, the asteroid Vesta, Jupiter, and Saturn; others are on their way to Pluto and to land on a comet; and three others are on their way out of the solar system. Another landed on the tiny asteroid Eros, only about 10 miles across, and a European craft landed on Saturn's larged moon, Titan. Samples have been returned robotically from the Moon, from a comet, from the Sun—in the form of the solar wind—and from the asteroid Itokawa."

Physics of Bubbles: supercomputer needed.

2013-05-14T19:32:00.000-04:00

It took one of the world's most powerful supercomputers five days to model a simple childhood past time: popping bubbles.

Image credit: Andreas Bastian

Researchers at the Lawrence Berkeley National Laboratory and at the University of California Berkeley have mathematically described the evolution of a cluster of bubbles. The research was published May 10, 2013 in the journal Science.

Bubbles and foams have been notoriously difficult to model mathematically. Whether a bubble pops and how its neighbors rearrange depend on phyiscal factors that take place at multiple length and time scales. For most materials, the thin fluid membrane between bubbles are thinner than a human hair, contain a proportionally huge amount of gas, and depend on the chemistry of the fluid.

In their paper, the researchers report that they were able to separate out the physical dynamics that take place at different length and time scales in a series of equations.

They had equations to describe how over many seconds, gravity thins out the fluid bubble wall as the bubble approaches popping. A separate set of equations described how, in less than a second, the bubbles rearrange after a neighbor pops. Still more predicted how liquid would flow at the intersection between bubbles.

By writing out a series of equations that describe different aspects of bubble dynamics, the researchers were able to overcome a longstanding challenge of describing a system that covers many time and length scales.

Combining these equations, the researchers used the Department of Energy's National Energy Research Scientific Computing Center (NERSC) to create a computer-generated model of popping bubbles.

In industry, clusters of bubbles belong to a class of materials called foams. From ocean froth, to soapy detergents, fire retardants, and bicycle helmets, foams play an large role in our day to day lives. The researchers hope that their robust model of foam physics will enable accurate modeling and innovation for a variety of industrial foams.