A handsome tokay gecko. Photo: Ethan Knapp and Alyssa Stark

Anyone who lives in or has visited a tropical country is likely familiar with the chipper chirping of the gecko. These friendly little lizards inhabit homes and jungles stretching from Indonesia to Tanzania to the Dominican Republic. They emerge after sunset, taking advantage of their night vision eyesight—which is 350 times more powerful than a human’s—and are welcome guests in homes and hotels since they gobble up mosquitoes and other insect pests.

In addition to the locals, scientists also love these colorful lizards. Geckos possess the unique ability among lizards to run up flat walls and scamper across ceilings, even if the surface is very smooth. Researchers have been puzzling over this ability for years, and dozens of labs have tested gecko adhesion in the hopes of harnessing this superpower for potential use in everything from robotics to space technology to medicine to “gecko tape.”

Gecko toes, it turns out, contain hair-like structures that form a multicontact interface, meaning geckos grip with thousands of tiny adhesive structures rather than what appears to be a single uniform foot.

Gaps remain, however, in researchers’ understanding of how gecko feet interact with surfaces in their natural environment, especially in dry versus wet conditions. Scientists know that gecko toe pads are superhydrophobic, or water repelling, yet geckos lose their ability to cling to glass when it becomes wet. Why don’t they just repel the water and cling to the glass surface below? Similarly, scientists wonder how geckos deal with wet leaves in the forest during rain storms.

A new paper published in Proceedings of the National Academy of Sciences investigates these mysteries. The authors decided to test gecko grip on a range of wet and dry materials that both attract and repel water. To perform their experiments, they outfitted six tokay geckos with gecko-sized harnesses. They placed the geckos onto four different types of materials, such as glass, plastic and a substance designed to mimic waxy tropical leaves. After giving the lizards some time to adjust to their new surroundings, the researchers applied a uniform tugging pressure onto the geckos’ harnesses, pulling in the opposite direction of where the animals were walking. Eventually, the geckos could cling no longer and lost their grip. This allowed the team to measure the adhesive force required to displace the animals. They repeated the same experiments under very wet conditions, too.

The authors found that materials that are more “wettable”—an indication of the degree to which a surface attracts water molecules—the less force it took to disrupt the clinging geckos’ grips. Glass had the highest wettability of the surfaces the researchers tested, and geckos easily slipped from wet glass compared to dry glass. When that material gets wet, water forms a thin, attractive film that prevents the gecko’s tiny toe hairs from coming into contact with the surface.

The low wettability properties of waxy leaves, on the other hand, allow geckos to establish a sturdy grip, even in rain storms, because leaves actively repel water. Geckos performed equally well in wet and dry conditions on the leaf-mimicking surface, the researchers found. 

How the geckos interact with surfaces depends upon a thermodynamic theory of adhesion, the authors conclude. These features are dictated by Van der Waals force, or the sum of attractive and repulsive interactions between gecko toes and the characteristics of the surfaces they come into contact with. So long as those attractive forces jibe, geckos are in luck for getting a grip on whatever surface they come into contact with, regardless of whether it’s wet or dry.

Using our whole-animal adhesion results, we found that wet surfaces that are even weakly [water repulsive] allow the gecko adhesive system to remain functional for clinging and likely locomotion as well.

Our findings suggest a level of versatility in the gecko adhesive system that previously was not accounted for and calls into question interesting evolutionary, ecological, and behavioral predictions.

In addition to shedding light on how gecko adaptations help the lizards cope with their natural environment, the authors think their findings may contribute to designing new synthetic gecko robots that may overcome real-life geckos’ wet glass Achilles’ heel, useful perhaps for cleaning skyscraper windows, spying on suspected terrorists, or simply changing a hard-to-reach light bulb.

The gooey confections can be used to measure the speed of light and demonstrate relationships between the volume of a gas and its pressure and temperature. Photo by Flickr user John-Morgan

If the Easter Bunny comes to your house this weekend, you may find yourself with a plethora of marshmallows and Peeps. What to do with them all? Aside from simply eating them, cooking with them, or unleashing your artistic side by making dioramas, consider using them….for science!

Marshmallows, it turns out, are must-have pieces of equipment for at-home science experiments. Sure, you can use them test your kids’ self control through the the field of psychology’s notorious marshmallow test and its ever-more complex iterations. But if you’d rather not torture your kids by leaving tantalizingly in reach a marshmallow they’re ordered not to have, consider trying these easy science projects:

Marshmallows in a vacuum

The relationship between the volume of a gas and its pressure can be demonstrated at home with a simple set up. Photo by Mohi Kumar

No, not that kind of vacuum, despite the intriguing possibilities conjured by this phrase. You’ll need:

• A glass jar with a lid
• A mechanism to pump some of the air out of the jar
• Marshmallows

The Physics Hypertextbook recommends using a kitchen vacuum pump for this experiment. Cutting a small hole in the jar’s lid and squeezing a wine preserver’s vacuum pump into it also works.

Place a few marshmallows in the jar, seal it, and then pump the air out:

What’s going on? Marshmallows are basically a foam spun out of sugar, water, air, and gelatin. The sugar makes them sweet, the water and sugar combo makes them sticky and the gelatin makes them stretchy. But the air–which actually makes up most of the confection’s volume–makes marshmallows the tastiest way to encapsulate a gas in a solid. As you pump air out of the jar, the air inside the marshmallow expands and the marshmallow puffs up. Release the seal, and the marshmallows return to their normal size.

Congratulations! You’ve just demonstrated Boyle’s Law, which states that when the temperature doesn’t change, that the relationship between pressure (which is decreased by pumping air out of the jar) and volume of any set amount of gas (the marshmallow) is inversely proportional. In other words, decreasing one necessitates an increase of the other.

If you can’t eat ‘em, nuke ‘em!

If you’ve ever roasted a marshmallow over a campfire, you’ll know where this next demonstration is going. You’ll need:

• A microwave
• A microwavable plate
• A standard-sized marshmallow (avoid minis or jumbos; the former will fry and the latter may make an enormous mess!)

Place the marshmallow on one of its flat sides in the center of a plate. Then microwave the marshmallow for, say, 45 seconds on high.

It’s alive! This time, rather than changing the pressure surrounding the marshmallow, you’re changing the temperature. As the microwave bakes the marshmallow, the water in the marshmallow heats up and warms the air. When air becomes hot, it expands, forcing the marshmallow to puff up. The confection’s water also softens the sugars, causing it to ooze, as seen in the video above (created by YouTube user bbbpwns).

The relationship between temperature and volume is representative of Charles’ Law, which holds that any set amount of gas will expand when heated–increasing the temperature of a gas necessitates an increase in the gas’ volume.

Trying this with Peeps makes for a slightly alarming outcome, showcased by YouTube user UBrocks:

If you flashed back to the Stay Puft Marshmallow Man, alas–the monster marshmallow you pulled from your microwave doesn’t last–it will cool and deflate into a glob of ooze. But before it cools completely, the ooze is quite malleable and can be sculpted into shapes. But careful! The marshmallow remnants are like naplam–they’ll stick to you and burn. After it cools a bit, brush some oil on your palms before you mold anything, else your sculpture will stay glued to your hands.

 A gooey way to calculate the speed of light

For this demonstration you need a bit of background knowledge as you start out. The speed of a wave can be calculated by multiplying the wavelength (the distance from crest to crest) with the frequency (the number of crest-to-crest cycles that repeat in a stretch of time). Light is a wave, and its speed can be calculated the same way without fancy equipment. You’ll need:

A child measures the distance between melted patches after a layer of marshmallows was microwaved. Photo by Mohi Kumar

• A microwave with the turntable removed
• A  glass casserole dish or baking tray
• Mini marshmallows
• A ruler
• A calculator

Take the baking tray and pack one layer of marshmallows along the bottom, lined up like tiny puffy soldiers.  Make sure the turntable is removed from the microwave–this allows microwaves to move through the glass and the marshmallows in a standing wave pattern. Cook for a few minutes on low, watching the marshmallows carefully. With the turntable removed, the microwave doesn’t heat evenly–you’ll notice melted patches forming in your marshmallow field.

As soon as you see a few such patches, remove the dish and measure the distance between two that form a line parallel to the microwave’s door–these mark the locations of highest amplitudes within the standing wave. Multiply this by two to get the full wavelength of the microwaves that passed through your marshmallows (if you look at the geometry of a standing wave, your initial measurement only gave you half the wavelength). Convert this into meters.

Multiplying this result by frequency of the microwave, found in the microwave’s manual or in a label inside the device, gives ~299,000,000 meters per second–roughly speed of light! Catch a video of this here.

Comet ISON, still just a faint glimmer at the crosshairs of this telescope image, could be the brightest comet in a generation next November. Image via E. Guido/G. Sostero/N. Howes

Over the past year, we’ve seen a ton of scientific milestones and discoveries of historic importance, from the discovery of the Higgs Boson to the landing of a mobile laboratory on Mars. Science, though, is defined by its relentless march forward: No matter how much we learn, there are always more questions to answer. So, after our roundup of 2012′s most surprising (and significant) scientific events, we bring you the most exciting studies, projects and science developments we’ll be watching for in 2013.

1. Comet Ison: Back in September, a pair of Russian astronomers discovered a new comet heading in our direction. At the time, it was just a faint blip detectable only with the most sophisticated telescopes, and it was unclear how visible it would become during its approach. Now, though, astronomers are predicting that when it passes by us and closely orbits the sun in November and December of 2013, it could be the astronomical sight of our lifetimes. “Comet Ison could draw millions out into the dark to witness what could be the brightest comet seen in many generations—brighter even than the full Moon,” astronomer David Whitehouse writes in The Independent. One thing’s for sure: we’ll be watching.

Russian scientists plan to drill the last few meters into the subglacial Lake Vostok in January and February in an attempt to collect water and sediment samples that have been isolated for millions of years. Image via National Science Foundation

2. Lake Vostok: For more than a decade, a team of Russian scientists has worked to drill nearly 12,000 feet down into Antarctica’s icy depths with a single purpose: to obtain samples from the ultra-deep isolated subglacial lake known as Lake Vostok. After barely reaching the water’s surface last Antarctic summer, they now plan to return at the end of 2013 to drill fully into the lake and use a robot to collect water and sediment samples. The lake may have been isolated for as long as 15 to 25 million years—providing the tantalizing potential for long-term isolated evolution that could yield utterly strange lifeforms. The lake could even serve as a model for the theoretical ice-covered oceans on Jupiter’s moon Europa, helping us better understand how evolution might occur elsewhere in the solar system.

Rival American and British teams were also racing to probe the depths of other subglacial lakes in search of life—the American team’s efforts to reach subglacial Lake Whillans is expected to meet with success this January or February, while the British have been forced to cease their drilling efforts into subglacial Lake Ellsworth due to technical difficulties.

Experts predict that algae-based biofuels, now on sale at a handful of spots in California, could take off in 2013. Image via Wikimedia Commons/Honeywell

3. Algae Fuel: Experts predict that 2013 will be the year when vehicle fuels derived from algae finally take off. A handful of biofuel stations in the San Francisco area started selling algae-based biodiesel commercially for the first time last month, and after the product met state fuel standards, the pilot program is expected to be expanded shortly. Because algae use less space, grow more quickly and can be more efficiently converted into oil than conventional crops used for biofuels, advocates are excited about the possibility that algae-based fuels could wean us off petroleum without using up precious food crops.

New findings about the cosmic microwave background, the energy resulting from the Big Bang that still radiates through the universe (imaged above), could help us better understand how space originally formed. Image via ESA/ LFI & HFI Consortia

4. Cosmic Microwave Background: Energy left over from the Big Bang still radiates through the universe—and the European Space Agency’s plans to use the Planck satellite to measure this energy more precisely than ever before could help us better understand the formation of the universe. The 1965 measurement of this microwave energy first supported the concept of the Big Bang, and subsequent examination of variations in the radiation has led to more sophisticated theories about our universe’s earliest days. The Planck satellite, launched in 2009, has already collected a wide range of valuable astronomical data and images, but plans to release all this info in early 2013 has the cosmology world all atwitter.

IBM’s Watson supercomputer could start helping doctors diagnosis illnesses in 2013. Image via IBM

5. Supercomputers to the Rescue: A number of supercomputers around the world could have a remarkable impact at solving problems in health, the environment and other fields over the next year. Yellowstone, a 1.5 petaflops cluster computer in Wyoming, was installed this past summer and will spend 2013 crunching numbers (1.5 quadrillion calculations per second, to be exact) to refine climate models and help us better understand how storms and wildfires move across the planet. Meanwhile, Watson, IBM’s world-famous Jeopardy-winning supercomputer, is currently being trained by doctors to recognize medical symptoms and serve as a diagnostic tool, providing treatment options based on case histories and clinical knowledge. So far, the computer has been trained to recognize breast, lung and prostate cancers.

A graphic data readout of the a collision of two protons, briefly producing a Higgs Boson, from the Large Hadron Collider. Image via CERN

The year 2012 was a major one for science. We saw scientists develop a new type of drug to combat HIV, figure out how to store digital data in DNA—fitting an astonishing 700 terabytes of information into a single gram of it—and even invent a coating for the inside of condiment bottles that could eliminate our stuck-ketchup-headaches once and for all (though, admittedly, this one is a little less groundbreaking than the others). Yet a few milestones in particular—discoveries, technological feats, realizations, and inventions—stand out:

1. The Higgs Boson: The landmark discovery by the European Organisation for Nuclear Research (CERN) of the once-mythical particle might be the most significant scientific discovery of our lifetimes, but it’s also one of the most surprising. Stephen Hawking, the Einstein of our time, famously bet Michigan physicist Gordon Kane $100 that it would never be found.

In an interview with The Atlantic, physicist Lawrence Krauss explained why so many experts had agreed with Hawking, arguing that the existence of the Higgs—a particle (and associated field) that makes certain types of elementary particles behave as though they had mass—was just too convenient, as it was originally posited simply to explain away an apparent difficulty in an otherwise appealing theory in theoretical physics.

The theory seeks to unite all physical forces under the same set of rules. But how can electromagnetic forces–governed by massless photons–fit under the same theoretical umbrella as the weak force, which is governed by bosons with discernible mass that control radioactive decay? Efforts to answer this conundrum gave birth to  the Higgs boson. Krauss noted,”It seemed too easy…It seemed to me that introducing an invisible field to explain stuff is more like religion than science…Great, I invented invisible hobgoblins to make things right.”

Incredibly, in this case, it turned out the hobgoblins were real.

An artist’s rendering of the theorized Earth-like planet, potentially capable of containing liquid water. Image via University of Hertfordshire/J. Pinfield

2. Earth-Like Planets: 2012 featured a ton of exoplanet discoveries, but the sighting of HD 40307g was without a doubt the most unexpected and exciting.  The planet, bigger than earth but not so large as to be a gas giant, seems to orbit in its sun’s “goldilocks zone” (not too hot and not too cold), making it potentially capable of hosting liquid water, considered a prerequisite for life as we know it.

Even better, it’s just 42 light-years away: distant by human standards, but fairly close by compared many of the astronomical objects, making future projects to observe the planet much more feasible.

A composite image of self-portraits taken by Curiosity on Mars. Image via NASA/JPL-Caltech/MSSS

3. Curiosity Reaches Mars: Okay, the mission itself wasn’t too surprising—it’s been in the works since 2004—but what was so astonishing was the sudden surge of public interest in the rover and in space exploration as a whole. For decades following the manned Apollo missions of the 1960s and 70s, general enthusiasm for space science had slowly ebbed. After Curiosity’s successful landing, though, it surged. Among other things, video of NASA engineers celebrating the feat went viral and the official Curiosity twitter account garnered some 1.2 million followers.

People are so interested in Curiosity‘s exploits, in fact, that even an engineer’s throwaway line about “a discovery for the history books” pumped up expectations so much that we were bound to be disappointed by the actual finding: that early Martian soil samples seem to be representative of what we know of the planet as a whole, and that its chemistry is complex enough to have potentially once supported life. Bigger news might come over the next few years, but as project scientist John Grotzinger said, “Curiosity’s middle name is patience.”

For many Americans, Superstorm Sandy drove home the idea that climate change is real. Image via NASA

4. Climate Change Is Even Worse Than We Thought: After decades of warnings from scientists that our greenhouse gas emissions will soon wreak havoc with the climate, we’re now starting to see the consequences—and they sure aren’t pretty. As a whole, experts are saying that the even the most frightening climate scenarios have proved to be too conservative in their analysis of how rising carbon dioxide concentrations will alter precipitation patterns, drive ocean acidification, lead to more powerful storms and, in general, make most parts of the planet grow warmer.

One silver lining might be that the public is now starting to acknowledge climate change as a present-day problem, rather than a hypothetical trend that could take effect in the future. Sadly, this has come only after record-breaking heat waves, droughts and the tragic impacts of Hurricane Sandy. Although the most recent international climate talks in Doha accomplished little, there are hopes that this shift in opinion could lead to a long-awaited change in policy sometime soon.

A digital rendering at the atomic level of a new type of water desalinization method developed at MIT, which uses a one-atom-thick sheet of graphene (blue) to filter impurities (green and purple ) from water molecules (red and white). Image via David Cohen-Tanugi

5. A New Way to Desalinate Seawater: With world populations expected to keep growing and potable water projected to grow more scarce over the coming century, a practical and cheap means of desalinating sea water is one of materials science’s holy grails. In July, MIT researchers announced the development of a new method of desalinization using one-atom-thick sheets of graphene, a pure carbon substance. Their method could be far cheaper and less energy-intensive than existing systems—potentially providing a way to solve many of the world’s water problems once and for all.

A new plastic-based lighting technology produces a consistent, silent white glow that’s pleasing on the eyes. Image by Ken Bennett, Wake Forest University photographer

Chances are, sometime today, you sat in an office, classroom or workplace lit by constantly humming fluorescent light bulbs. Although they’ve long been favored by those who design buildings for their energy efficiency, fluorescent tubes are widely detested by those who sit in them because of the fact that they hum, flicker at a just-barely-perceptible rate, and emit an unsettling green tinge.

Now, while we search for replacements for the now-phased-out incandescent bulb, a group of researchers from Wake Forest University offers a potential solution. As they described yesterday in an article published in the journal Organic Electronics, they’ve harnessed a technology called field-induced polymer electroluminescence (FIPEL) to produce a constant, energy-efficient, soft white light.

“People often complain that fluorescent lights bother their eyes, and the hum from the fluorescent tubes irritates anyone sitting at a desk underneath them,” said David Carroll, one of the scientists leading the team. “The new lights we have created can cure both of those problems and more.”

The technology can be used to produce lights in a variety of shapes and sizes, from large panels to small, household-sized squares. Image by Ken Bennett, Wake Forest University photographer

The technology converts an electrical charge into light with three layers of a white-emitting plastic polymer matrix that incorporates trace amounts of nanomaterials that glow when stimulated. The team says the consistent white light that is produced has a similar spectrum to natural sunlight, so it’s also more pleasant to the human eye than the blue-tinged glow of LED lights. Researchers have been working to make FIPEL-based bulbs viable for some time, but this is the first instance of a practical use of the technology to produce light.

“[LEDs] have a bluish, harsh tint to them, ” Carroll told BBC News, “it is not really accommodating to the human eye; people complain of headaches and the reason is the spectral content of that light doesn’t match the Sun—our device can match the solar spectrum perfectly.”

His team also claims a number of other advantages for FIPEL. It’s more than twice as energy efficient as compact fluorescent (CFL) bulbs and roughly as efficient as LEDs. Unlike both of these bulbs, though, the bendable FIPEL technology is shatter-proof, so there’s no risk of contaminating a home or office with hazardous chemicals. It’s also extremely long-lasting: the researchers say a single FIPEL bulb may work effectively for up to a decade. Office workers will be especially excited to hear that it’s perfectly silent while in operation.

“What we’ve found is a way of creating light rather than heat,” he told BBC, explaining how his team’s devices achieve such a high level of energy efficiency. “Our devices contain no mercury, they contain no caustic chemicals and they don’t break as they are not made of glass.”

Additionally, the new technology can be manufactured in a variety of sizes and shapes. It could be incorporated into small bulbs with Edison sockets to fit light fixtures in homes, as well as large sheets to replace florescent tubes in offices. Although the team has focused on using it to make white light thus far, it can be altered to produce different colors, so it could eventually prove useful in large displays, such as public advertisements and storefronts.

The team says they’re currently partnering with a company to produce FIPEL-based bulbs on a broad scale and that the bulbs could be available to consumers sometime in 2013.

An MIT study reveals that carbon dioxide directly reduces the strength of ice, regardless of temperature. Image via Wikimedia Commons/Christof Berger

It’s well established that, in the years to come, increasing amounts of carbon dioxide in the air will cause the climate to change, thereby leading to the ice caps melting at an accelerated rate and worldwide sea level rise. A new scientific finding, though, points at a troubling, entirely separate direct effect of carbon on ice—one that has nothing to do with warming at all.

As documented in a study published yesterday in the Journal of Physics D, researchers from MIT have discovered that merely being in the presence of increased concentrations of carbon dioxide causes ice to significantly weaken, with reduced material strength and fracture toughness, regardless of temperature. With enough carbon dioxide in the air, this alone could make glaciers more likely to split and fracture. Add in the fact that global temperatures will continue to warm—especially around the poles—and the combination of these two factors could mean that the ice caps will melt at even faster rates than experts have previously projected.

“If ice caps and glaciers were to continue to crack and break into pieces, their surface area that is exposed to air would be significantly increased, which could lead to accelerated melting and much reduced coverage area on the earth,” said the study’s lead author, Markus Buehler. “The consequences of these changes remain to be explored by the experts, but they might contribute to changes of the global climate.”

Buehler and his co-author, Zhao Qin, used computer simulations at the atomic level to evaluate the dynamics of ice strength in the presence of various concentrations of carbon dioxide. They found that the gas diminishes the strength of ice by interfering with the hydrogen bonds that hold together the water molecules in an ice crystal. Specifically, at the atomic level, the carbon dioxide competes with the bonded water molecules and, at high enough concentrations, displaces them from the bonds and takes their place.

The carbon dioxide molecules start infiltrating a piece of ice at an outer edge, then slowly split it apart by migrating inward as a crack forms. In doing so, they also attract water molecules outward to the edge by forming bonds with the water molecules’ hydrogen atoms, leaving broken bonds within the crystalline structure and decreasing the ice’s strength overall. The simulations showed that ice that has been infiltrated with carbon dioxide to the point that the gas occupies two percent of its volume is roughly 38 percent less strong.

“In some sense, the fracture of ice due to carbon dioxide is similar to the breakdown of materials due to corrosion, e.g., the structure of a car, building or power plant where chemical agents ‘gnaw’ at the materials, which slowly deteriorate,” Buehler told Environmental Research Web. Since glaciers typically begin to break apart with the formation of small cracks, the researchers say, this could lead to further large-scale fractures, such as the one that recently occurred in Antarctica and produced a fragment larger than New York City.

Because the finding is the first evidence of this phenomenon, it’s too early to say just how much it will accelerate ice melt beyond previous predictions. There are several mechanisms, though, by which it could lead experts to revise upward their estimates for ice melt and sea level rise given a continued increase in greenhouse gas emissions.

In addition to the obvious—that warmer air plus weaker ice means a faster rate of melting—there is the fact that the ice caps play a crucial role in reflecting sunlight back into space. Currently, they cover roughly seven percent of the earth’s surface but are responsible for reflecting 80 percent of the sun’s rays. This is because ice’s bright white color helps it reflect light more efficiently than nearly any other type of ground cover.

If increased carbon dioxide concentrations and warmer temperatures cause ice to melt unexpectedly quickly, though, this bright white ice will be replaced by dark ocean water. More and more sunlight would enter and stay in the atmosphere, thereby causing more and more warming. This positive feedback loop could constitute one of the dreaded “tipping points” that climatologists fear might send our climate on an uncontrolled path towards calamity.

Since the paper only deals with ice at the microscopic level, the next step would be testing the effect of increased carbon dioxide concentrations on ice in a lab setting to check if the effects of the simulated model hold true. Of course, if nothing changes in terms of carbon emissions, we might well have the chance to see if these effects occur on a much larger scale—in the world’s glaciers and polar ice caps.

An electron scanning micrograph of the molecule-weighing device. When a molecule lands on the bridge-like portion at the center, it vibrates at a frequency that indicates its mass. Image via Caltech/Scott Kelberg and Michael Roukes

How much do you think a molecule weighs? A molecule, which is single group of bonded atoms—the two hydrogens and one oxygen that make up H2O, for example—is almost incomprehensibly tiny. One mole of water, which is roughly 0.64 ounces, has 602,214,078,000,000,000,000,000 molecules. Molecules, in short, are really, really, really small.

Up until now, scientists could only calculate the mass of large groups of molecules, by ionizing them (giving them an electric charge) and then seeing how strongly they interacted with an electromagnetic field, a technique known as mass spectrometry. They had no way, however, of measuring the mass of a single molecule.

But yesterday scientists from Caltech announced the invention of a device that directly measures the mass of an individual molecule. As described in a paper published in the journal Nature Nanotechnology, the tiny apparatus is built around a bridge-like structure that vibrates at a specific frequency based on the mass of the molecule on top of it. By precisely tracking the vibrating frequency of the bridge, they can determine the exact mass of the molecule.

“The critical advance that we’ve made in this current work is that it now allows us to weigh molecules—one by one—as they come in,” says Michael Roukes, the principle investigator of the lab that produced the paper. “Nobody’s ever done this before.”

To the naked eye, the device is essentially invisible—the scale at the bottom of the microscope image above is two microns long, or two millionths of a meter. The vibrating bridge at its center is technically known as a nanoelectromechanical system resonator and has been under development for over a decade.

In previous work, published in 2009, the researchers showed that they could measure the mass of particles sprayed onto the apparatus but with one limitation: It wasn’t sensitive enough to measure just one molecule at a time. Because the specific location where a particle landed affected the vibrating frequency, and the scientists had no way of knowing exactly where this would be, they needed to apply several hundred identical particles in order to find an average, which revealed the mass.

The advance makes use of a new insight into the way the vibrating frequency of the bridge changes when a molecule is sprayed onto it. The vibrations occur in two modes simultaneously: The first mode is side-to-side swaying, while the second mode occurs in the form of an oscillating S-shaped wave that moves up and down the bridge. By analyzing exactly how each of these modes change when the molecule hits the device, the researchers found they could determine its position, and thus its exact mass.

In the study, the researchers demonstrated the effectiveness of the tool by measuring the mass of a molecule called immunoglobulin M, or IgM, an antibody produced by immune cells in the blood and that can exist in several different forms. By weighing each molecule, they were able to determine exactly which kind of IgM it was, hinting at potential future medical applications. A kind of cancer known as Waldenström macroglobulinemia, for instance, is reflected by a particular ratio of IgM molecules in a patient’s blood, so future instruments building on this principle could monitor blood to detect antibody imbalances indicative of cancer.

The scientists also envision this type of device as an aid to biological researchers looking into the molecular machinery inside a cell. Since the enzymes that drive a cell’s functioning are highly dependent on molecular attachments on their surface, precisely weighing proteins at various times and in different types of cells could help us better understand cellular processes.

The team even predicts that their invention could have everyday commercial applications. Environmental monitors that track nanoparticle pollution in the air, for instance, could be activated by arrays of these vibrating bridges.

Importantly, the scientists say, the device was constructed using standard semiconductor fabrication methods—the same used in common electrical circuits—so it can theoretically be scaled up to apparatuses that include hundreds or tens of thousands of the single-molecule sensors operating at once. “With the incorporation of the devices that are made by techniques for large-scale integration, we’re well on our way to creating such instruments,” says Roukes.

Climate change could produce an ozone hole over the U.S. similar to the one observed over Antarctica, above, in 2006. Image via NASA

For the past 25 years, it seemed that we’d pretty much solved the ozone problem. In the 1970s and 80s, people around the world grew increasingly alarmed as research revealed that chemicals we were producing—such as CFCs, used in refrigeration— had started destroying the crucial ozone layer, high up in the atmopshere, that protects us from the sun’s harmful UV radiation. In response, world governments came together to sign the Montreal Protocol in 1987, which phased out the production of ozone-depleting chemicals. The concentration of these chemicals in the atmosphere leveled off within a decade.

Yesterday, though, Harvard scientists hit us with some bad news: It looks as if climate change could actually cause the depletion of the ozone layer to resume on a wide scale, with grim implications for the United States.

“If you were to ask me where this fits into the spectrum of things I worry about, right now it’s at the top of the list,” said professor James Anderson in a press release, discussing his team’s paper, published online in Science. “What this research does is connect, for the first time, climate change with ozone depletion, and ozone loss is directly tied to increases in skin cancer incidence, because more ultraviolet radiation is penetrating the atmosphere.”

The revelation comes from the researchers’ observation that warm-temperature summer storms can force moisture high up into the stratosphere, a layer of the atmosphere that sits about 6 miles above our heads. Typically, storm updrafts are halted at a boundary just below the stratosphere, but in a series of observation flights above the U.S., the team saw that storms with sufficient power injected water vapor into the stratosphere via convection currents.

Normally, the stratosphere is bone dry. In the Arctic and Antarctic, though, the presence of holes in the ozone layer is tied to moisture. Because water vapor raises the air temperature in the immediate vicinity, it allows compounds such as chlorine—leftover from CFCs, which will remain in our atmosphere for decades—to undergo a chemical shift into a free radical form, which then depletes ozone. In the warmer air above the U.S., the researchers measured that the local presence of water vapor increased the rate of ozone erosion as high as one hundredfold.

Because this mechanism has only been detected now, there are no historical data about how much water vapor has been moved upward by such storms over time, and so the researchers can’t say just how much total increased ozone depletion has occurred so far. But their concern is the future. The problem is that, as previous studies have shown, climate change is likely to mean more warm-temperature storms, especially over populated mid-latitude regions such as ours.

As a result, despite the best efforts of the Montral Protocol, the erosion of the ozone layer might accelerate in the coming century. The particularly troubling aspect of this discovery is that it puts highly-populated areas at risk, as compared to the polar regions previously observed.

“There has been a major effort by the medical community to define the relationship between decreases in ozone and the subsequent increases in skin cancer,” Anderson said. “The answer is quite clear–if you multiply the fractional decrease in ozone protection by about three, you get the increase in skin cancer incidence. There are 1 million new skin cancer cases in the U.S. annually–it’s the most common form of cancer, and it’s one that’s increasing in spite of all the medical research devoted to it.”

Much more field research is needed to track the rate of water vapor injections into the stratosphere, the attendant ozone depletion and the prevalence of skin cancer in the U.S. population. But as long as greenhouse gas emissions rise, the trend will likely continue. “We don’t know how rapidly the frequency and intensity of these storms will increase, so we can’t place a time scale on this problem, but the core issue here is quite straightforward and simple, because we understand this chemistry,” said Anderson

“In my mind, this is not just a broad public health issue,” Anderson added. “This is about actually being able to step out into the sunlight.”

One hundred years ago, in 1912, astronomer Vesto Slipher of the Lowell Observatory, in Flagstaff, Arizona, attempted to figure out the speed of Andromeda, the closest spiral galaxy to our own Milky Way. As he examined the shift in wavelengths that indicate Andromeda’s motion relative to us, he was surprised by what he found. Unlike nearly every other galaxy, which (we would soon learn) is moving away from us, indicating that the universe is expanding, Andromeda was doing something quite unusual: heading straight for us at a speed of 250,000 miles per hour.

Scientists were unsure what this would mean for our galaxy in the long-term. Would we collide directly with Andromeda, a galaxy roughly the same size as our Milky Way? Or would we slide past it, like two ships passing in the night? Now, as indicated in a paper published last week in the Astrophysical Journal, we know the Milky Way’s ultimate fate: a galactic collision.

“We’ve known for 100 years that Andromeda is getting closer to us, but to really know the trajectory it’s going to take, you need to know its sideways motion,” said Roeland van der Marel, an astronomer at the Space Telescope Science Institute and an author of the study. If Andromeda were moving enough on a sideways trajectory, it could have meant that it would fail to collide with the Milky Way, instead moving laterally past our galaxy.

“What we’ve done now is, for the first time, actually obtained a measurement for the sideways motion, using the Hubble space telescope,” he said, “and it turns out that the Andromeda galaxy is heading straight for us. Previously, this was a well-reasoned conjecture, and now it’s really a demonstrated fact.”

Scientists are now fairly certain that the Milky Way and Andromeda will collide and merge in roughly 4 billion years, as depicted above. Illustration by NASA; ESA; Z. Levay and R. van der Marel, STScI; T. Hallas; and A. Mellinger

As shown in the NASA computer animation above, the Milky Way and Andromeda will be slowly drawn together due to their mutual gravitational pull, colliding roughly 4 billion years from now. Subsequently, the two galaxies will orbit around each other before merging in one big galactic pile-up. “On the first passage, they may either hit each other directly, smack on the face, or they may sort of just graze each other,” van der Marel said. “But either way, after that first passage, they get slowed down a lot, and that slowing down leads them to fall back together and merge as one.”

The resulting supergalaxy will be different from either of the current ones: Instead of the elegant, flat, spiral-shaped disc we know and love, the new galaxy will be a three-dimensional ball of stars.

The research team used images captured by the Hubble Space Telescope to determine the exact degree of sideways motion of Andromeda relative to our galaxy. ”To measure the sideways motion, you basically take an image, you wait a couple of years, and then you do it again and look if things have shifted,” van der Marel said. The researchers looked at images of three specific sections of Andromeda, taken either five or seven years apart, and used distant galaxies in the background—from our vantage point, behind Andromeda—as a stationary reference to compare them with.

“In the end, we found that there is a shift, and it was about one hundredth of a pixel on the cameras on Hubble,” he said. In other words, not enough to avert a collision in our distant future.

Astoundingly, this massive crash won’t have an enormous impact on earth, or the solar system as a whole. “Galaxies are mostly empty space, so there are lot of stars in them, but when the galaxies collide, individual stars don’t actually collide like billiard balls,” said van der Marel. “No star from Andromeda will actually directly hit our sun, and in fact, no star from Andromeda will even come close enough to the sun to perturb the orbit of the earth.” Instead, gravitational forces will fling the solar system as a whole outward within the new galaxy, so our night sky will change as we explore a different portion of the universe.

Regardless, the much bigger issue for life on earth is an unrelated long-term problem: the sun will gradually increase in temperature and then run out of nuclear fuel around the time the galaxies finish merging, 6 billion years from now, making the existence of life on this planet virtually impossible.

So, since this galactic collision isn’t something we need to fear, maybe we ought to welcome it. Perhaps we can begin by figuring out a name for our new supergalaxy. The Milkydromeda? The Andro Way? Clearly, suggestions are welcome. We’ve got roughly 4 billion years to figure something out.

The last transit of Venus happened in 2004, but the next won't be until 2117

Every century or so, something truly special happens in the sky, and it happens twice: Venus passes in between the sun and earth. The transit of Venus, as it’s called, comes in pairs spaced exactly 8 years apart, with each pair separated by gaps more than 100 years long. As a result, only 8 transits have occurred since the invention of the telescope.

The most recent one was in 2004, and the second half of the pair is next week, during sunset on June 5th for North American observers, and during sunrise on June 6th for many in Europe and Asia. After this, the next one isn’t until 2117.

Why does it happen so rarely? Two events need to occur at the exact same time for us to see a transit of Venus. First, Venus needs to pass between us and the sun, so that to an observer looking down at the solar system, all three bodies would be in a straight line. This happens every 584 days, as shown in the bottom part of the diagram below.

Transits of Venus are so rare because the planet must pass between earth and the sun while lining up vertically, as well

However, Venus also needs to line up vertically so that it appears somewhere in front of the face of the sun from our vantage point. Because Venus and the earth don’t orbit the sun on the exact same plane—Venus’ orbit is tipped 3.4 degrees relative to ours—most of the time it’s too high or too low, as shown in the top part of the diagram. It only lines up in all 3 dimensions and traverses across the sun four times during an unusual 243 year cycle, with the transits coming in pairs separated by alternating periods of 121.5 and 105.5 years.

In the United States, the transit will begin at roughly 6:04 Eastern, 5:04 Central, 4:05 Mountain, and 3:06 Pacific Time. Over the course of several hours, Venus will appear as a small dot moving slowly against backdrop of the sun. As with a solar eclipse (or anytime, really), looking directly at the sun can severely damage your retinas, so you should use a special filter or simply project the sun onto the ground or a piece of paper, by holding up a piece of cardboard with a small hole punched in it and allowing the sunlight to pass through.

Historically, the transit of Venus played an important role in helping astronomers learn about the dimensions of our solar system, says Owen Gingerich, professor of astronomy and history of science at the Harvard-Smithsonian Center for Astrophysics. “The first observed transit was in 1639, but it was in 1716 that the astronomer Edmund Halley noticed that the geometry of it could be useful in determining the distance to the sun,” he says. “At the time, the relative distances between the planets was well known, but not the absolute scale of the solar system, and without the absolute scale, you couldn’t know how big the sun was.”

When the next pair of transits came, in 1761 and 1769, the scientific world was ready. “There was an international campaign set up to make the observations, and you needed observers from as far removed places on earth as you could get,” says Gingerich. Scientists were dispatched to everywhere from Newfoundland to Tahiti to gather as much data as possible, and at each location, observers attempted to measure as accurately as possible just how long it took Venus to traverse the sun.

As Halley had pointed out, if one knew the exact distance between two points on earth—Newfoundland and Tahiti, for example—and also calculated the difference in how long it took Venus to traverse the sun from each of these vantage points, the principle of parallax could be used to determine the size of the sun itself, and with that our distance from it. “From each observatory, you would get a slightly different measurement for the length of Venus’ path,” Gingerich says. “And in fact, if you take three of the best observations from 1769 and use them in the calculations, you get a result within 1 percent of the modern value of the size of the sun.”

Although the transit is no longer as scientifically significant as it was in the 18th century, it will still provide valuable data for many observers. Our ongoing discoveries of planets in other solar systems, for example, depends on the intermittent dimming of distant stars as their planets pass in front of them. Calculating just how much Venus causes the sun to dim during the transit might help us more accurately understand these far-flung exoplanets.

Whether you watch the transit to make complex calculations about exoplanets or just to see something unusual in the sky, we have just one recommendation: You’d better not miss it. The next few transits will be in December 2117, December 2125, June 2247 and June 2255. Your grandchildren and great-grandchildren might be watching, but you won’t be around to see another one.

Scientists calculated how to make a force field big enough to fit the Millennium Falcon. Photo courtesy of Mary Evans / Lucas Film / Ronald Grant / Everett Collection (10336353)

Today, if you aren’t already aware, is something of an intergalactic holiday. In recent years, May 4th has become an unofficial day to honor the iconic film series Star Wars, because the date is a rhyming pun of the signature line, “May the Force Fourth Be With You.” All around the world, Star Wars fans are celebrating Luke, Leia, Boba Fett and (maybe even) the Ewoks.

We decided to channel our inner Jedi by checking out the contributions science has made towards a better understanding of the Star Wars universe. Last year, it turns out, a team of physicists from the University of Leicester in Britain took a closer look at many fans’ favorite spacecraft: Han Solo and Chewbacca’s hyperspace-traveling Millennium Falcon (which made the Kessel Run in less than 12 parsecs!)

The scientists noted that force fields are often employed in the Star Wars universe to provide a barrier between the hangars of spaceships and outer space, preventing the ship’s atmosphere from being sucked outwards (think of spacecraft flying inside the Death Star‘s massive hangar bay, with no mechanical airlock). The physicists noted that a real-life innovation, the plasma window, could theoretically serve to create such force fields. Plasma windows, invented by Brookhaven Lab physicist Ady Hershcovitch in 1995, use magnetic fields to create bounded areas filled with plasma (superheated, viscous ionized gas), which have the special property of blocking air from entering a vacuum while allowing radiation and physical objects to freely pass through.

With this knowledge in hand, the research team decided to try calculating the amount of energy that would be necessary to create a docking force field large enough to accommodate the Millennium Falcon, which they estimate is roughly 100 by 40 by 6 feet. Their conclusion? Theoretically possible with current technology—but generating sufficient amounts of energy to continuously sustain a force field that size is unlikely to be feasible.

But, in a galaxy far, far away, anything is possible.

A growing number of clocks automatically synchronize with a radio signal and don't have to be adjusted for Daylight Saving Time. How do they work?

As Daylight Savings Time approaches, you’ll be seeing many reminders to shift your clocks an hour forward just before going to sleep on Saturday night. This got us thinking about the clocks that set themselves. Available widely for as little as $10 or $15, these radio-controlled clocks are increasingly popular, as they adjust automatically to time shifts and will work virtually anywhere in the continental United States. You may well own one of them already. But you may not know how they work.

This clock’s low-tech appearance conceals an elaborate system for keeping it precisely in tune with what the National Institute of Standards and Technology deems official time: a clock calibrated by the movement of a clump of cesium atoms in Boulder, Colorado. Housed at the NIST’s Physical Measurement Laboratory, this is the official atomic clock, and it keeps time for the entire country.

The NIST's cesium fountain atomic clock, in Boulder, Colorado

The sophisticated apparatus—known as NIST-F1—is the latest in a line of high-tech atomic clocks and was officially adopted as the U.S.’s time standard in 1999. The accuracy of NIST-F1 is continuously improving, and as of 2010, scientists calculated that its uncertainty had been reduced to the point that it will neither gain or lose a second over the course of 100 million years.

This degree of accuracy is achieved by a complex technological setup. In 1967, the International Bureau of Weights and Measures officially defined a single second as the time it takes a single cesium atom to transition between energy levels a given number of times—that is, cesium’s natural resonance frequency. NIST-F1 is known as a cesium fountain atomic clock because it uses a fountain-like array of lasers to manipulate cesium atoms and detect this frequency as accurately as possible.

Inside the device, six powerful lasers are aimed at a gas containing cesium atoms, slowing down their movement and cooling them down to temperatures just millionths of a degree above absolute zero. Next, a pair of vertical lasers push the clumped ball of cesium atoms about a meter upward in the cavity, which is filled with microwave radiation. As it drifts back downward, another laser is pointed at the atoms and detects how many were altered by the microwaves. Scientists calibrate the microwave frequency to maximize the number of atoms affected.

The NIST uses this measure of cesium’s resonance frequency as the official second for the U.S. primary time standard. But how does it get to your radio-controlled clock? The official time standard is sent to WWVB, NIST’s shortwave radio station in Fort Collins, Colorado. Once per minute, WWVB uses five antennas to broadcasts a digital code indicating the official time—including the year, date, hour, minute and whether Daylight Savings Time is in effect—across the country.

Most radio-controlled clocks are programmed to receive this signal once per day with built-in receivers and calibrate their time accordingly. Experts say that your radio-controlled clock will work best when positioned near a window facing the source of the broadcast, Fort Collins. Many other countries have their own official time broadcasts, based on other atomic clocks.

A clock that stays accurate for 100 million years is pretty good, right? Not for NIST. In 2010, they announced advances in developing a new “quantum logic clock,” which keeps time based on a single atom of aluminum. The new clock will neither gain nor lose a second over 3.7 billion years, the researchers report, giving it the title of the world’s most precise clock.

So this year, if your clock automatically jumps an hour ahead at 2 a.m. Sunday, remember that an intricate setup of lasers and atoms thousands of miles away is the reason why. We’ve sure come a long way from watching sundials and winding watches.

The microwave field around the objects without (left) and with the cloaking material (right). Image from "Experimental Verification of three-dimensional plasmonic cloaking in free space"

For years, science-fiction and fantasy authors have dreamed up magical objects—like Harry Potter’s invisibility cloak or Bilbo Baggins’ ring—that would render people and things invisible. Last week, a team of scientists at the University of Texas at Austin announced that they have gone one step further toward that goal. Using a method known as “plasmonic cloaking,” they have obscured a three-dimensional object in free space.

The object, a cylindrical tube about 7 inches long, was “invisible” to microwaves, rather than visible light—so it’s not like you could walk into the experimental apparatus and not see the object. But the achievement is nonetheless quite stunning. Understanding the principles of cloaking an object from microwaves could theoretically lead to actual invisibility soon enough. The study, published in late January in the New Journal of Physics, goes beyond previous experiments in which two-dimensional objects were hidden from various wavelengths of light.

How did the scientists do it? Under normal conditions, we see objects when visible light bounces off them and into our eyes. But the unique “plasmonic metamaterials” from which the cloak was made do something different: they scatter light in a variety of directions. ”When the scattered fields from the cloak and the object interfere, they cancel each other out and the overall effect is transparency and invisibility at all angles of observation,” said Professor Andrea Alu, co-author of the study.

To test the cloaking material, the research team covered the cylindrical tube with it and subjected the setup to a burst of microwave radiation. Because of the plasmonic material’s scattering effect, the resulting mapping of microwaves did not reveal the object. Other experiments revealed that the shape of the object did not affect the material’s effectiveness, and the team believes that it is theoretically possible to cloak multiple objects at once.

The next step, of course, is creating a cloaking material capable of obscuring not only microwaves, but visible light waves—an invisibility cloak we might be able to wear in everyday life. Alu, though, says that using plasmonic materials to hide larger objects (like, say, a human body) is still a ways away:

In principle, this technique could be used to cloak light; in fact, some plasmonic materials are naturally available at optical frequencies. However, the size of the objects that can be efficiently cloaked with this method scales with the wavelength of operation, so when applied to optical frequencies we may be able to efficiently stop the scattering of micrometre-sized objects.

In other words, if we’re trying to hide something from human eyes using this method, it’d have to be tiny—a micrometre is one-thousandth of a millimeter. Still, even this could be useful:

Cloaking small objects may be exciting for a variety of applications. For instance, we are currently investigating the application of these concepts to cloak a microscope tip at optical frequencies. This may greatly benefit biomedical and optical near-field measurements.

In 2008, a Berkeley team developed an ultra-thin material with the potential to someday render objects invisible, and earlier this year, a group of Cornell scientists funded by DARPA was able to hide an actual event 40 picoseconds long (that’s 40 trillionths of a second) by tweaking the rate of light’s flow.

Invisibility cloaks may still be years away, but it seems we’ve entered the Age of Invisibility.

A fruit fly. Image by Flickr user *dougmino*

Gravity potentially affects all biological processes on Earth, even though this may be hard to believe while we watch flies walking around on our ceilings as though gravity did not matter to them at all. Of course, gravity is only one factor, and other factors such as adhesion or buoyancy determine whether an organism falls off the ceiling, say, or how long it takes an organism to settle to the ground.

We’ve known for a long time that humans are harmed by long periods in low-gravity environments. Astronauts return from space with muscle atrophy and reduced bone mass. These effects seem to get worse over time, so understanding the effects of gravity on human physiology is essential when planning long-distance space flights. Studying the effects of low gravity in space craft and space stations is expensive. Anyone who has spent time working in a laboratory knows that many experiments have to be redone numerous times just to get the procedures to work properly. If a key step in carrying out an experiment on, say, the response of cells to lack of gravity, is “shoot the experiment into space and keep it there for two months” then it will take a very long time and a lot of money to get results one might need to make sense of low-gravity biology. Therefore, it would be nice to have an anti-gravity machine in our Earth-bound laboratories to run experiments without the cost and scheduling constraints imposed by space flight.

There is a way to simulate weightlessness at a small scale in the lab. A team of researchers from several European institutions have used magnetism to offset the effects of gravity at the cellular level. The method is called diamagnetic levitation. (Another method for simulating anti-gravity uses a “Random Positioning Machine” (RPM).)  Some materials—diamagnetic materials—are repelled by a magnetic field. Water and most biological tissues fall into this category. A very powerful magnetic field can be applied to these tissues to offset the effects of gravity, so molecules moving about and doing their thing inside cells do so as though there were no gravity acting on them. According to a recent study, it appears that gene expression is affected by gravity. (The paper is published in BMC Genomics and is available here.)

The magnet used in this experiment produces a field with a force of 11.5 Tesla (T). The Earth’s magnetic field is equal to about 31 micro Teslas. The magnet holding your shopping list to your refrigerator is about .005 Tesla, the magnets in a loudspeaker are about 1 to 2 Teslas in strength, and the magnetic force of an MRI or similar device, for medical imaging, is usually about 3 Teslas or less. If you were to attach a magnet of 11.5 Teslas to your refrigerator, you would not be able to pry it off.

In this experiment, the magnet was used to “levitate” fruit flies for 22 days as they developed from embryos to larvae to pupae and eventually to adults. The flies were kept at a certain distance above the magnet where the net repulsive effect of the magnet on the water and other molecules was equal to and opposite of the effects of gravity. Other flies were placed below the magnet at the same distance, where they experienced the equivalent of double the Earth’s gravity.

The study examined how the expression of genes differed depending on the simulated gravitational field as well as in a strong magnetic field that did not simulate a change in gravity. Doubling the Earth’s gravity changed the expression of 44 genes, and canceling out gravity altered the expression of more than 200 genes. Just under 500 genes were affected by the magnetic field alone, with expression of the genes being either increased or decreased. The researchers were able to subtract the effects of magnetism from the effects of increased or decreased gravity and thus isolate which genes seemed to be most sensitive to changes in gravity alone. According to the researchers, “Both the magnetic field and altered gravity had an effect on gene regulation for the flies. The results of this can be seen in fly behaviour and in successful reproduction rates. The magnetic field alone was able to disrupt the number of adult flies from a batch of eggs by 60%. However the concerted effort of altered gravity and the magnet had a much more striking effect, reducing egg viability to less than 5%.”

The most affected genes were those involved in metabolism, the immune system’s response to fungi and bacteria, heat-response genes and cell signalling genes. This indicates that the effects of gravity on the developmental process in animals is profound.

The most important outcome of this research is probably the proof of concept: It demonstrates that this technique can be used to study the effects of low gravity on biological processes. We can expect more-refined results that inform us of specific processes that are altered by gravity, and possibly develop ways of offsetting those effects for humans or other organisms on long-distance space flight. Eventually, we may be able to send a fruit fly to Mars and return it safely.

Herranz, R., Larkin, O., Dijkstra, C., Hill, R., Anthony, P., Davey, M., Eaves, L., van Loon, J., Medina, F., & Marco, R. (2012). Microgravity simulation by diamagnetic levitation: effects of a strong gradient magnetic field on the transcriptional profile of Drosophila melanogaster BMC Genomics, 13 (1) DOI: 10.1186/1471-2164-13-52

The first Death Star from Star Wars (via Wookieepedia)

Obi-Wan: That’s no moon. It’s a space station.

That space station was the Empire’s first Death Star in Star Wars: A New Hope. Obi-Wan and company had just bounced through a debris field, the remnants of the planet Alderaan. Such an act of destruction would seem impossible to us–it seemed so to many of the movie’s characters until it happened. But perhaps not, say three students at the University of Leicester in England who last year published a study on the subject in their university’s undergraduate physics and astronomy journal.

The study’s authors start off by making some simple assumptions: The planet being fired upon doesn’t have some sort of protection, like a shield generator. And it’s about the size of Earth but solid through and through (Earth isn’t solid, but the planet’s layers would have significantly complicated the math here). They then calculate the planet’s gravitational binding energy, which is the amount of energy required to pull apart an object. Using the mass and radius of the planet, they calculate that destruction of the object would require 2.25 x 10³² joules. (One joule is equal to the amount of energy required to lift an apple one meter. 10³² joules is a lot of apples.)

The energy output of the Death Star isn’t given directly in the movie, but the space station was said to have had a “hypermatter” reactor that had the energy output of several main-sequence stars. For an example of a main-sequence star, the authors look to the Sun, which puts out 3 x 10²⁶ joules per second, and they conclude that the Death Star could “easily afford to output [the energy required for an Earth-like planet's destruction] due to to its tremendous power source.”

It would be a different story, though, if the planet scheduled for destruction had been more like Jupiter than Earth. The gravitational binding energy of Jupiter is 1,000 times that of the Earth-like planet in the study. “To destroy a planet like Jupiter [the space station] would probably have to divert all remaining power from all essential systems and life support, which is not necessarily possible.”

Of course, that assumes that the Emperor wouldn’t be willing to sacrifice a space station full of people to wipe out his enemies. And considering that he was just fine with wiping out whole planets, I’m not sure I’d take that bet.