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What’s At The Bottom Of The Deepest Hole On Earth?

Environment





Photo credit:

Rakot13 / Wikimedia Commons

Remove this rusted metal cap and the world’s deepest hole tunnels miles into the Earth. However, we know more about certain distant galaxies than we do about what lies miles beneath our very own feet. For that reason, Soviet scientists in the 1970s decided to probe deeper than humanity has ever done before. For the next 24 years, they drilled on and off into the Earth’s crust. 

Why Does Snow “Squeak” When Stepped On?

Despite the mid-March thaw this week, this past winter will long be remembered for record snowfall across much of the U.S. Weeks of snowstorms, bitter cold, dangerous commutes and backbreaking shoveling sessions can can harden even the season’s most avid fans.

 

Still, for anyone standing in a gentle snowfall for the first time, watching the air turn into little bits of fluffy ice, the experience can be magical. And if the snow falls through particularly cold air, which holds less moisture than does warmer air, you will often hear tiny squeaks walking (or driving) through it. Much about snow formation is known science, but that last part—the squeak—is little studied and less understood.

 

Snow forms when supercooled water droplets collide with specks of dust suspended in the air and freeze. They can take the shape of everything from classic six-sided dendrites and needles to pellets and chaotic crystals. It is actually rare for a pristine dendrite to make the trip from the cloud to your tongue unaltered. More likely, flakes will hit other supercooled droplets to form heavier, hard-packed pellets called graupels. They make the best snowballs, but stepping on this denser snow usually creates a crumpling sound. The fluffiest snow is mostly aggregate—low-moisture dendrites that run into one another and freeze together. It is aggregate that offers up the pleasing squeak.

 

To get an idea why this might be, Scientific American spoke with W. Craig Carter, a materials scientist at Massachusetts Institute of Technology who has spent some time contemplating the squeaks of winter. Carter's lab works to produce predictive models for complex, micro- and nanoscale behavior of materials such as those in batteries. He has also collaborated on several art projects that incorporate aspects of materials science, natural design and mythology.

 

[An edited transcript of the interview follows.]

 

Not all dry snow squeaks. Why?

Freshly fallen dry snow goes "whoof" when you step on it. The snow has to sit awhile in cold conditions and collapse slightly under its own weight before it will squeak.

 

Fresh snow is just sitting there, with flakes loosely touching. Something has to happen to the snow, and I think that something is the collapse [when the snow melts minutely and refreezes]. Tiny bonds—they're like welds a couple-hundred nanometers in size—form between each flake. You know how a bucket of ice cubes in your freezer eventually becomes one big piece of ice? The cubes are bonding together in a process called sintering, and I think that's what is happening on a nanoscale with the snow. Sintering—the growth of these tiny necks between ice crystals—takes place over a matter of hours. The necks support the weight of the snow and stop it from collapsing any further under its own weight.

 

The necks squeak when they're broken?

I think so, yes. And they are breaking sequentially, from the top of the snow to the point where your foot stops sinking because you've compacted it. With wet snow, it's one of two things. The bonds might be more liquid or there also might be more water generally to lubricate the flakes. Stepping on that gives you the classic crumpling sound.

 

So the noise we hear is the sound of the tiny bonds cracking?

Yes, I think you have it: tiny bonds cracking. At larger scales, it would sound like compressing an old, stale Rice Krispies treat—the bonds being sugar bridges, perhaps. At larger scales, it might sound a bit like the crunch you hear as the garbage truck compresses the trash.

 

Does the squeaking happen only with classic six-sided flakes?

My hunch is that larger-pellet snow wouldn’t squeak so much as crunch. I believe the squeak depends on the fallen snow forming the welds to sinter together. These small particles can form from either [denser] flakes or aggregate flakes, either by partial melting and refreezing or as a morphological change that occurs just below the water’s melting point. If one were to look at snow that squeaks, it would look like a Rice Krispies treat, but at a very small scale.

 

What drew you to this specific question? Do you ski or maybe you've just suffered one too many Northeast winters?

It is just one of those things that I’ve observed, and it struck my curiosity. I did think about it on a recent weekend’s long walk with my dog. I like that squeaking sound very much—but I’ll be happy to see spring arrive soon.

 

How satisfied are you with your theory?

In my mind it's still just in idea. I can't poke any holes in it but I wouldn't say I have tremendous confidence in it. If I sat down and did some back-of-the-envelope numbers, I might be more confident.

 

Is there an envelope and pencil on your desk?

[laughing] It's one of those things. It's a question of time and a cost-benefit analysis. And no one is handing out Nobel's for solving the squeak in snow.

 

This is a fun topic, but I can't help but think there might be some practical applications for the information, maybe in materials science?

Yes, there are many similar phenomena in natural and technical materials. Most of the practical ones would have to do with the sintering process involved in making ceramics. The fundamental idea is that capillarity [the rise or depression of a liquid in small areas such as the space between fibers or small tubes] dominates at the smallest scales. Capillarity can cause things to stick together—and it can also cause an isolated particle to change its shape so as to reduce its surface energy.

2 Common Liquids Spontaneously Form Dancing Droplets [Video]

Nate Cira was working in a lab as an undergraduate at University of Wisconsin–Madison when he saw something unusual. He was working with a mixture of food coloring and water, placing droplets on an ultra-clean slide—and the droplets seemed to be breathing. They were dancing, too: multiple droplets would race around and crash into one another in complicated patterns.

Now after three years of work as a graduate student at Stanford University, Cira and colleagues have derived the physics behind the strange behavior of those droplets. The mechanism behind their motion could help scientists understand how complex movement and interactions emerge from simple ingredients.

To figure out what was going on inside these droplets Cira and his collaborators, physical biology researcher Manu Prakash and postdoctoral student Adrien Benusiglio, placed tiny tracer beads in droplets of the food coloring–water mixture so that they could see the flow of fluids within the droplets. Then they did a series of experiments to see how multiple droplets with different concentrations would interact with one another. They described their findings, which can explain complex behavior in many different mixtures of two substances, in Nature March 11. (Scientific American is part of Nature Publishing Group.)

On an extremely clean slide a droplet of water or of food coloring will form a flat pool instead of beading up. The water–food coloring combo, however, formed rounded beads. By watching the motion of the tracer particles, the researchers figured out why. The particles would cycle from the center of a droplet to the edges as water vapor evaporated from the droplet's surface and left the less-evaporative food coloring behind. Then, because water has higher surface tension than food coloring does, the more concentrated water at the center pulled the liquid and particles back in. This continuous flow, caused by the evaporation process and the difference in surface tension between the two fluids, holds the droplet in place so it cannot spread out. (The flow from lower to higher surface tension is called the Marangoni effect.) “It’s like an engine running in idle,” Prakash says. “There’s this internal flow running, but it’s perfectly symmetric, so the drop doesn’t go anywhere.”

Putting the droplet near another one breaks that symmetry and gets the droplet moving: The water vapor exuded by nearby droplets slows the evaporation on the side closest to them, so more water builds up on that side thereby pulling the droplet forward toward the vapor’s source, even from millimeters away. Droplets with a lower water concentration will race towards droplets with a higher one, push them forward and eventually fuse.

[youtube https://www.youtube.com/watch?v=ZMsaH...]

Once they had hammered out the physics behind the behavior of the droplets, they put them to work. Using a Sharpie, they drew a series of obstacle courses on glass slides. Because the water–food coloring mixture avoids the Sharpie’s hydrophobic ink, the droplets would follow the contours of the tracks. On a circular track, for example, a low-concentration droplet could chase a high-concentration one for minutes at a time. On other tracks, the droplets would self-assemble into lines or oscillate regularly up and down.

The researchers also set up a self-sorting system much like a coin-sorter. In it droplets would bounce along a series of Sharpie-drawn boxes holding different, multicolored mixes, propelled away by the high-water-content droplets until they found the box with their same concentration. In addition, using droplets on multiple slides, the researchers coaxed them into forming liquid lenses that aligned themselves automatically into focus.

And that “breathing” effect Cira spotted as an undergraduate? It was the water vapor in Cira’s own breath that caused the droplet to pulse in and out.

The physical process that Cira’s group uncovered could prove useful in many contexts. “New mechanisms are like bricks from which engineers can build houses,” says John Bush, a fluid dynamicist at Massachusetts Institute of Technology. “This is a beauty.” He says it is hard to predict the applications that stem from such a discovery but that they could be plentiful; using tiny amounts of fluids to transport substances is a growing field, and this solves a key problem of forces keeping fluids pinned in place.

Similar droplets form when any two nonreactive liquids mix, as long as one has higher surface tension and evaporates more quickly. (Just ask the lab members—at one point they tried every combination of chemicals in the lab, some of which had explosive results.) The group says that such mixes could eventually be used in microfluidic devices, to prepare surfaces for painting by cleaning and drying them, or even to rove around cleaning the surface of solar panels.

But the real draw is the demonstration of complexity from such commonplace ingredients and how it can inform our understanding of life and biology. “Clearly this is a nonliving system, and it’s very, very simple compared to what biological entities do, but it has sensing and motility combined together,” Prakash says. “And that’s very powerful.” The team will be posting instructions for how to produce the droplets on their website.

Mass Deaths in Americas Start New CO2 Epoch

The atmosphere recorded the mass death, slavery and warfare that followed 1492. The death by smallpox and warfare of an estimated 50 million native Americans—as well as the enslavement of Africans to work in the newly depopulated Americas—allowed forests to grow in former farmland. By 1610, the growth of all those trees had sucked enough carbon dioxide out of the sky to cause a drop of at least seven parts per million in atmospheric concentrations of the most prominent greenhouse gas and start a little ice age. Based on that dramatic shift, 1610 should be considered the start date of a new, proposed geologic epoch—the Anthropocene, or recent age of humanity—according to the authors of a new study.

 

"Placing the Anthropocene at this time highlights the idea that colonialism, global trade and the desire for wealth and profits began driving Earth towards a new state," argues ecologist Simon Lewis of Leeds University and the University College of London. "We are a geological force of nature, but that power is unlike any other force of nature in that it is reflexive, and can be used, withdrawn or modified."

 

Lewis and Mark Maslin, a geologist at UCL, dub the decrease in atmospheric carbon dioxide the "Orbis spike," from the Latin for world, because after 1492 human civilization has progressively globalized. They make the case that human impacts on the planet have been dramatic enough to warrant formal recognition of the Anthropocene epoch and that the Orbis spike should serve as the marker of the start of this new epoch in a paper published in Nature on March 12. (Scientific American is part of Nature Publishing Group.)







The Anthropocene is not a new idea. As far back as the 18th century, the first scientific attempt to lay out a chronology of Earth's geologic history ended with a human epoch. By the 19th century, the idea was commonplace, appearing as the Anthropozoic ("human life rocks") or the "Era of Man" in geology textbooks. But by the middle of the 20th century, the idea of the Holocene—a word which means "entirely recent" in Greek and designates the most recent period in which the great glacial ice sheets receded—had come to dominate, and incorporated the idea of humans as an important element of the current epoch but not the defining one.

 

That idea is no longer sufficient, according to scientists ranging from geologists to climatologists. Human impacts have simply grown too large, whether it's the flood of nitrogen released into the world by the invention of the so-called Haber-Bosch process for wresting the vital nutrient from the air or the fact that civilization now moves more earth and stone than all the world's rivers put together.

 

Researchers have advanced an array of proposals for when this putative new epoch might have begun. Some link it to the start of the mass extinction of large mammals such as woolly mammoths and giant kangaroos some 50,000 years ago or the advent of agriculture around 10,000 years ago. Others say the Anthropocene is more recent, tied to the beginning of the uptick of atmospheric CO2 concentrations after the invention of an effective coal-burning steam engine.

 

The most prominent current proposal connects the dawn of the Anthropocene to that of the nuclear age—long-lived radionuclides leave a long-lived record in the rock. The boom in human population and consumption of everything from copper to corn after 1950 or so, known as the "Great Acceleration," roughly coincides with this nuclear marker, as does the advent of plastics and other remnants of industrial society, dubbed technofossils by Jan Zalasiewicz of the University of Leicester, the geologist in charge of the group that is advocating for incorporating the Anthropocene into the geologic time scale. The radionuclides can then serve as what geologists call a Global Stratotype Section and Point (GSSP), more commonly known as a "golden spike." Perhaps the most famous such golden spike is the thin layer of iridium found in rock exposed near El Kef, Tunisia, that tells of the asteroid impact that ended the reign of the dinosaurs and thus marked the end of the Cretaceous Period about 65 million years ago.





 

Lewis and Maslin reject this radionuclide spike because it is not tied to a "world-changing event," at least not yet, though it is a clear signal in the rock. On the other hand, their Orbis spike in 1610 reflects both the CO2 nadir as well as the redistribution of plants and animals around the world during that time, a literal changing of the world.

 

Much like the golden spike that marks the end of the dinosaurs, the proposed Orbis spike itself would be tied to the low point of atmospheric CO2 concentrations around 1610, as recorded in ice cores, where tiny trapped bubbles betray past atmospheres. Further geologic evidence will come from the appearance of corn pollen in sediment cores taken in Europe and Asia at that time, among other indicators that will complement the CO2 record. Therefore, scientists looking at ice cores, mud or even rock will find this epochal shift in the future.





 

The CO2 drop coincides with what climatologists call the Little Ice Age. That cooling event may have been tied to regenerated forests and other plants growing on some 50 million hectares of land abandoned by humans after the mass death brought on by disease and warfare, Lewis and Maslin suggest. And it wasn't just the death of millions of Americans, as many as three-quarters of the entire population of two continents. The enslavement (or death) of as many as 28 million Africans for labor in the new lands also may have added to the climate impact. The population of the regions of northwestern Africa most affected by the slave trade did not begin to recover until the end of the 19th century. In other words, from 1600 to 1900 or so swathes of Africa may have been regrowing forest, enough to draw down CO2, just like the regrowth of the Amazon and the great North American woods, though this hypothesis remains in some dispute.

 

Whether in 1610, 1944 or 50,000 B.C., the new designation would mean we are living in a new Anthropocene epoch, part of the Quaternary Period, which started more 2.5 million years ago with the advent of the cyclical growth and retreat of massive glaciers. The Quaternary is part of the Cenozoic, or "recent life," Era, which began 66 million years ago, which is, in turn, part of the Phanerozoic ("revealed life") Eon, which started 541 million years ago and encompasses all of complex life that has ever lived on this planet. In the end, the Anthropocene might supplant its old rival the Holocene. "It is only designated an epoch, when other interglacials are not, because back in the 18th century geologists thought humans were a very recent species, arriving via divine intervention or evolving on Earth in the Holocene," Lewis argues, but scientists now know Homo sapiens arose more than 200,000 years ago in the Pleistocene epoch. "Humans are a Pleistocene species, so the reason for calling the Holocene an epoch is a relic of the past."

 

Maslin suggests downgrading the Holocene to a stage within the Pleistocene, like other interglacial spans in the geologic record. But Zalasiewicz disagrees with this bid to get rid of the Holocene. "I don't see the need," he says. "Systematic tracing of a Holocene / Anthropocene boundary globally would be a very illuminating process in all sorts of ways."

 

The changes wrought by humans over the course of the last several centuries, if not longer, will echo in the future, whether in the form of transplanted species, like earthworms or cats, crop pollen in lake sediments or even entire fossilized cities. Still, whether the Anthropocene started tens, hundreds or thousands of years ago, it accounts for a minute fraction of Earth's history. And this new epoch could end quickly or endure through millennia, depending on the choices our species makes now. "Embracing the Anthropocene reverses 500 years of scientific discoveries that have made humans more and more insignificant," Maslin notes. "We argue that Homo sapiens are central to the future of the only place where life is known to exist."

 

Large Study Concludes Homeopathy Does Not Effectively Treat Any Health Condition

Health and Medicine





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Patricia Chumillas/shutterstock.com

Homeopathy is an alternative form of medicine that uses very small doses of harmful substances—which may cause symptoms in a healthy person—to treat those same symptoms in someone who’s ill. Some think that the “memory” of the original substance (usually chemicals or plant and animal material) retained in the highly diluted preparations will help provoke the body into action. Others say homeopathy is not only ineffective, it’s dangerous, especially when used as a substitute for approved treatments with a good record of safety and effectiveness.

New Photographs Show Surface Of Venus

Space





Photo credit:

B. Campbell, Smithsonian, et al., NRAO/AUI/NSF, Arecibo

Venus, sometimes referred to as Earth’s “evil twin,” is a hellish place. It’s the hottest world in our solar system, boasting temperatures of close to 480oC (900oF), hot enough to melt lead.

New Laser Surgery Can Turn Your Eyes From Blue To Brown For $5000

Technology





Photo credit:

muratart/ Shutterstock

In the classic 1930s movie, "The Wizard of Oz," Dorothy asks the good citizens of Oz whether they could dye her eyes to match her gown, and they happily oblige. Of course, eyes are not like hair, and 75 years on you still cannot dye your eyes to suit your outfit. But it turns out that you can actually change their color with the aid of a laser.

Florida Bans the Term “Climate Change”; or, Orwell Visits Miami

Climate change denialFlorida

Florida has banned the phrase “climate change,” at least as far as the staff of the state’s environmental agency are concerned. Also “global warming.” And “sustainability” is verboten, too, according to an investigative report in the Miami Herald. 

This policy seems to have started in 2011, when Florida Governor Rick Scott—who has repeatedly insisted that he is unconvinced that climate change is caused by human activity— appointed Herschel Vinyard Jr. as director of the Florida Department of Environmental Protection (DEP). Thereafter, DEP employees were warned “to beware of the words global warming, climate change and sea-level rise”—“these words were to be prohibited for use from official DEP policy-making with our clients.”

The department denies that there is any such policy in place, but the Herald reported that “former DEP employees from offices around the state say the order was well known and distributed verbally statewide.”

Does it seem silly to think that employees at the Florida DEP worried about being turned in for seditious thinking to Governor Scott, who hovers over them scrutinizing their faces for hints of thoughtcrime? One former DEP employee told the Herald that “using the terms in reports would would bring unwanted attention to their projects.”

Such restrictions on the free flow of scientific discussion are neither new nor confined to Florida: 

In 2007, two employees of the Fish and Wildlife Service attending an international conference on Arctic research were ordered “not to speak on or answer questions about ‘climate change, polar bears and sea ice.’”
NASA climate researcher James Hansen endured years of politically-based censorship, and was instructed to submit his lectures, papers, and interview requests for approval from his supervisors.
Legislators in North Carolina have attempted to shield the state from sea-level rise by forbidding state employees from considering sea-level rise in projections.
Even normally congenial Canada faced a scandal when the government of Stephen Harper began a policy of censoring government scientists, requiring them to “alter information for non-scientific reasons,” and to obtain prior permission even to tweet on Twitter. (When the government fears what can be said in 140 characters, it’s time to fear the government, eh?)

Restricting scientists from discussing climate change, to say nothing of restricting them from even using the term “climate change,” is symptomatic of a denial of reality so deep that it evokes magical thinking. If you don’t use the magic words, this thinking goes, then the bad thing won’t come true. Instead of facing the reality of climate change, instead of taking practical steps such as the immediate construction of higher levees around Miami, Florida politicians hide their heads in sand—at least for as long as there is beach sand left in Florida.

In keeping with this brand of denialism, Governor Rick Scott has responded to the Miami Herald article by denying that the use of “climate change” was banned at the DEP and by refusing to be specific about the DEP’s position on global warming. “Asked three more times about the issue, he repeated essentially the same answer.” Just keep repeating those magic words over and over, until it becomes real ...

But does it really matter if Florida dictates the terms scientists can and can’t use? Can’t scientists just use other words to convey information about the climate?

A naive view of language sees it as a means to convey information. A realpolitik view understands that language is a weapon, a political weapon of social control—those who dictate the rhetoric influence how people think. Language can be as coercive as the gun on a cop’s belt. And so it matters a great deal whether scientists are able to use accurate terms such as “climate change,” or whether they are forced to use euphemisms. Language guides and restricts thoughts.

Perhaps no one understood this so well as George Orwell. In his 1946 essay “Politics and the English Language,” Orwell concluded, “Political language … is designed to make lies sound truthful and murder respectable,” and that in corrupting language for this purpose, that mutilated language in turn corrupts thought.

In 1984, Orwell took this further. His character Syme explained Newspeak, the language that he helped the Party to create, this way:

You don’t grasp the beauty of the destruction of words. Do you know that Newspeak is the only language in the world whose vocabulary get smaller every year?… Don’t you see that the whole aim of Newspeak is to narrow the range of thought? In the end we shall make thoughtcrime literally impossible, because there will be no words in which to express it. … How could you have a slogan like ‘freedom is slavery’ when the concept of freedom has been abolished?

How can we talk about climate change when we can’t use accurate and precise language to describe it? Freedom may be slavery, and in Florida ignorance may pass for political strength, but accepting anything less than full and open scientific discourse would be doubleplusungood.

New 600-Million-Year-Old Fossil is the World’s Oldest Sponge

Plants and Animals





Photo credit:

A scanning electronic microscope image of the 600 million-year-old sponge-like animal fossil / Zongjun Yin

We shared a common ancestor with SpongeBob SquarePants hundreds of millions of years ago, though exactly how long ago has been up for debate. Now, analyses of a newly discovered 600-million-year-old fossil suggests that sponge-like animals predate the Cambrian by 60 million years. And if an advanced sponge-like form was already around during the Precambian period, that means that similarly advanced fossils of our (very early) ancestors from that long ago are also waiting to be found.

Bioelectrical Signals Can Stunt or Grow Brain Tissue

The brain is a hotbed of electrical activity. Scientists have long known that brain cells communicate via electrical missives, created by charged atoms and molecules called ions as they travel across the membranes of those cells. But a new study suggests that in the days and weeks that lead up to a brain forming in an embryo or fetus, altering the electrical properties of these cells can dramatically change how the ensuing brain develops.

 

Researchers at Tufts University and the University of Minnesota have investigated how the difference in charge on either side of a resting cell’s membrane—its electrical potential—helps build the brain. In previous work Tufts University developmental biologist Michael Levin found that patterns of electrical potentials in the earliest stages of an embryo’s development can direct how an animal’s body grows, and that manipulating those potentials can cause a creature to sprout extra limbs, tails or functioning eyes. Now, Levin’s group has investigated how these potentials shape the brain.

 

Working with frog embryos the researchers first used dyes to see the patterns of electrical potentials that precede brain development. They noticed that before the development of a normal brain the cells lining the neural tube, a structure that eventually becomes the brain and spinal cord, have extreme differences in ionic charge within and outside the membrane that houses the cells. In other words, these cells are extremely polarized.



Next Levin and his colleagues injected genetic material into some cells to spur the development of additional ion channels in the membrane. The channels allow charged atoms and molecules to travel into or out of cells; the extra channels enabled ions to cross more easily, thereby reducing how polarized these cells had become. In turn these electrical changes caused the brain to develop abnormally, with certain brain regions growing in too small or completely failing to develop. The observations led the team to conclude that the pattern of potentials they had disrupted may be a key component to healthy brain development, a bioelectrical blueprint for the brain.

 

Deeper study, as detailed in their paper in The Journal of Neuroscience on March 10, revealed that even the patterns of electrical potential in cells far from the neural tube were crucial to normal growth. The researchers also identified the molecular mechanisms—particularly the role of signals from calcium ions—involved in this effect.



University of California, San Diego neurobiologist Nicholas Spitzer, who did not participate in this study but has studied the brain’s electrical signaling extensively, finds the research convincing and notes that this mechanism-level understanding helps clarify ongoing questions about electricity’s part in shaping the brain. He suspects that future work will uncover an even greater role for such signaling.

 

As in their previous studies of limbs and eyes, Levin and his colleagues tested the strength of their bioelectrical blueprint elsewhere in the body to see whether it would spur neuronal growth in locations far from the brain. Although they could not grow a second brain elsewhere in the body, they succeeded in growing full neural tissue. “I think this is really amazing—equally important as the growth of additional eyes,” says University of California, Davis, biologist Min Zhao (also unaffiliated with the study) who investigates the application of electrical fields in wound healing.



In addition, Levin and his colleagues worked with a frog population carrying a genetic defect that would cause abnormal brain growth. They confirmed that these frogs exhibited abnormal electrical patterning during early development. By treating the animals with drugs that target specific ion channels, the researchers could restore normal patterns to ensure healthy brain growth, rescuing the brain from its genetic fate.

 

Altogether the findings could inspire novel interventions to heal the brain, whether to regenerate brain cells lost to degenerative disease or in remedying birth defects due to environmental toxins. In contrast to targeting genetic sources of dysfunction, Levin believes electrical manipulation could serve as a larger-level and more efficient control dial for brain development. 



The work also furthers our understanding of the interplay between genes, chemistry and electricity in the brain’s earliest stages. “These are issues in brain development that people never talk about,” Levin says. “This work could provide a road map for new approaches.”