Sunday, 31 October 2010

Johnald's Fantastical Daily Link Splurge

Johnald's Fantastical Daily Link Splurge

What the Frak? Battlestar Galactica’s Science Explained

Posted: 30 Oct 2010 04:00 AM PDT

When the science fiction drama Battlestar Galactica ended in 2009, it left some geeks wanting answers. How can a humanoid robot plug directly into a spaceship? How does Galactica's faster-than-light travel work? And what the frak was up with the mitochondrial Eve thing?

Read a exclusive excerpt from the new book by Patrick Di Justo and Kevin Grazier, The Science of Battlestar Galactica.

To find out, spoke with Patrick Di Justo, Wired magazine contributing editor and co-author of the new book, The Science of Battlestar Galactica. Together with the show's science advisor, NASA scientist Kevin Grazier, Di Justo jumps beyond the red line to delve into the science behind the story — and discovers that some things lie beyond what science can reach.

Spoiler alert: Major plot points ahead. What was the purpose of this book?

Patrick Di Justo: Battlestar Galactica has been called "a science fiction show without the science." There are some episodes of Galactica that are almost like The West Wing, they dealt more with politics…. They never really highlighted the science in the show unless it drove the plot. That was very good from a dramatic point of view, but it did leave a lot of science unexplored and unexplained in the show.

So we thought, hey, no one's really building up the science in the show, and it's there. Why don't we do it? So in the show's philosophy, who wins in the science-versus-drama battle?

Di Justo: There's actually a quote in the book, where it says, "Drama wins every time." That's essentially it. It's not that they completely threw science out the airlock. It's just that there would be times when they wouldn't mention or play up the science. Can you give an example?

DiJusto: Very basically, how could Cylons pass medical tests? They never explained that, never went into any detail about it. It was just accepted that Cylons could be so wonderfully indistinguishable that it would take a demented genius like Gaius Baltar to build a special type of machine that could differentiate the two. You wouldn't tell them apart from a standard medical test. And the show never explains how that works, how that happens — it just happens.

Same thing with the FTL drive. They never explain how it happens, it's just spin up the drives and whoosh — off you go. It seems like sometimes the physics of how the FTL drive works changes to fit what would be the most dramatic thing.

Di Justo: In the book, we explain that they never really locked down how the FTL drive worked, until they actually needed the details for a plot point. As long as you could reasonably say, okay, let's FTL jump out of here, that's all you needed to know — until an aspect of the drama required you need to know how it works. People have raised parallels between Battlestar Galactica and our own world, and not just in the way the final episode plays out. Can you talk a bit about that?

Di Justo: Think about what the mood in this country was like in 2003. We were still scared from the Sept. 11 attacks. We had this problem of, who can you trust? People were seeing terrorists under every bridge, it seemed.

And here you had a science fiction property from nearly 25 years before that covered almost all of those fears and feelings that we were having. So the show, it did what I believe science fiction is supposed to do. It takes us to the future, out in space. It takes us away from our current day, so that we can turn around and look at ourselves through a different lens. What kind of messages or cautionary tales do we get from the treatment of these questions in Battlestar?

Di Justo: One of the show's executive producers, David Eick, said, "We're not doing our jobs if, at least once a week, the viewer doesn't ask. 'Am I rooting for the wrong team?'"

Here, at least in America in 2003 when the show first came on, so many people were insisting that they knew this was right, these people were evil, we are the right people.

Then this show came along, which paralleled or mirrored that. You've got these Colonials who we're sure are right, and the Cylons who we're sure are evil and bad. But over the course of the first couple of seasons, sometimes maybe the Colonials aren't right all the time. Sometimes maybe the Cylons aren't evil all the time. Eventually you get to the point where the Colonials are doing suicide bombings against the Cylons. Here we are saying suicide bombing is just plain-out bad, and before you know it the good guys are doing it. Are they still the good guys?

My opinion is, if you had done that on American television with Americans and Muslim terrorists, and if you had blurred the line between the two, my God, the show would have been off the air before the episode had ended.

Yet by putting it in outer space, by making the bad guys manufactured robots, you could tell that same story, you could blur those lines. But you're not doing it in such an obvious way that would make people get their defenses up. That's what science fiction has been doing since the very, very beginning. What are some other parallels and differences between Colonials, Cylons and Earth humans?

Di Justo: Well, we talked about blood type at Comic Con in New York. Another key thing is, in the episode "A Measure of Salvation," a subgroup of Cylons come across an old beacon that happens to be contaminated with lymphocytic encephalitis. They're sickened, they're on the verge of death. If they're not helped soon, they're all going to die.

Doctor Cottle explains that the Colonials are immune to this disease. They're just absolutely fine, while the Cylons are dying.

That sounds really cool, but when you start to look into it, we, the people on the planet Earth in 2010, we are not immune to lymphocytic encephalitis. We get sick. Sometimes if we're not careful, we die.

Right there in the third season, we did not know how the show was going to end. But we got a really strong clue that Colonials are one type of people, Cylons are another type of people, and we humans really do seem to be halfway between both of them. We do seem to be a link, somehow, between them. And eventually at the end of the series we found out that we are the descendants of both groups. What about Cylon neural structure? Are there brain differences between Cylons and humans?

Di Justo: At the very beginning, in the miniseries, where Commander Adama says that the radiation on Ragnar is affecting the Cylon's silica pathways to the brain: For myself, I was thinking of dark silicon, like the stuff a CPU is made out of.

Until Dr. Grazier pointed out that a fiber-optic cable is also a silica pathway. Instead of dark silica, like a CPU, what is more likely is that they have fiber optics jacking up their neural systems. Which is how, when you see one of the Number Eight Cylons jam a fiber-optic cable into her arm and reprogram a computer, that's how that happens. They have fiber-optic nerves. And that lets them interface with any computer like a USB?

Di Justo: That's what we're seeing, yeah.

Exclusive Excerpt: The Science of Battlestar Galactica

Posted: 30 Oct 2010 04:00 AM PDT

Spoiler alert: This excerpt contains details of the final scene of the final episode. If you don't know why Hera Agathon is important, you may want to finish watching the series before reading.

Mitochondrial Eve

In the last scene of the last episode of Battlestar Galactica, Angel Six and Angel Baltar appear behind a bearded man (Ron Moore, in a goodbye cameo) at a New York newsstand, reading an issue of National Geographic magazine over his shoulder. Angel Six, in voiceover, reads, "Mitochondrial Eve is the name scientists have given to the most recent common ancestor for all human beings now living on Earth." We're supposed to assume they're referring to Hera, Helo and Athena's half-Colonial, half-Cylon daughter.

Find out more about the science of Battlestar Galactica in a Q&A with Patrick Di Justo.

Patrick DiJusto is co-author of the new book The Science of Battlestar Galactica. He is a contributing editor at Wired magazine and has written for Popular Science, Scientific American, New York Magazine and The New York Times tech blog, Circuits.

Lords of Kobol! An actual admitted scientific mistake!

The problem arises from the conflation of two very different terms: "Mitochondrial Eve," and "most recent common ancestor." The Most Recent Common Ancestor is, as the name suggests, the most recent common ancestor of all humans alive on this planet. Mitochondrial Eve is the most recent common ancestor of all humans along the matrilineal line. And to explain the difference—as always—we need a little background.

Biological cells come in two main types: prokaryotes and eukaryotes. For our purposes, the most important difference is that eukaryotes have a distinct nucleus and distinct organelles with their own membranes, while prokaryotes generally have neither. Mitochondria are tiny organelles embedded deep in the cytoplasm of almost every cell in your body. They have been called biological batteries or powerhouses because their chief task is to convert glucose into adenosine triphosphate (ATP), the energy unit of cellular metabolism.

Though mitochondria are embedded in your cells, they are self-contained entities, very similar to prokaryotes. For this reason, biologist Lynn Margulis suggested in 1966 that billions of years ago, primitive mitochondria actually were prokaryotes that entered into a symbiotici relationship with other cells. That hypothesis was reinforced in the 1980s when researchers showed that mitochondria have their own set of DNA, different from their parent cell.

Geneticists almost immediately realized that DNA from the mitochondria (mtDNA) could help them to track evolution and heredity along the female line. Since sperm do not contribute mitochondriaii to the developing embryo, an analysis of mtDNA can help to track matrilineal descent through the use of specific DNA markers. And because mtDNA isn't repaired as efficiently as nuclear DNA, it mutates approximately ten times faster.

Since mtDNA comes only from the mother, you will have that same code sequence in your DNA; if you are female, you'll pass that code sequence to your children. If you happen to have a mutation to your mtDNA, you'll pass that mutation, which will be shared with all of your subsequent descendants. By tracking layers of mutations backwards, geneticists can determine which populations are ancestors to which other populations.


Mitochondrial Eve is the term given to the woman who was the matrilineal most recent common ancestor for all humans living on planet Earth today. Passed down from mother to offspring, the mitochondrial DNA of every human is directly descended from hers. Although they lived thousands of years apart, Mitochondrial Eve has a male counterpart in Y-chromosomal Adam, the patrilineal most recent common ancestor. By tracking mtDNA mutations, scientists have determined that Mitochondrial Eve lived approximately 170,000 years agoiii, give or take a few tens of thousands of years. She most likely lived in East Africaiv, when modern Homo sapiens was branching off as a species distinct from other humans.

It's important to emphasize that Mitochondrial Eve and her contemporaries had offspring, and those offspring had other offspring. But throughout the subsequent generations, for one reason or another, the lineages of Eve's contemporaries all died out. Of all the women alive then (and in our case, that means the entire female population of Galactica and the fleet), only one has offspring alive today. We know her as Hera Agathonv.

This does not necessarily mean that Hera is our Most Recent Common Ancestor (MRCA). Hera populated today's Earth solely through her daughters and daughters' daughters. The MRCA is the person who, while no doubt descended from Hera, populated today's Earth via their daughters and/or sons. By adding males to the mix, the MRCA almost certainly cannot be the same as Mitochondrial Eve. In fact, most researchers today feel that the MRCA lived only about five thousand years ago, 145,000 years after Hera.

Does such a recent MRCA imply that the human race was once nearly wiped out, where it had to bring itself back with a small number of survivors after almost going extinct? Not necessarily. If cousins mate with each other, as has been known to happen in tightly knit tribal societies, then the number of ancestors each person could have would be constrained. In some societies, even more recent MRCAs are possible.

There was a real population bottleneck in our history. It took place seventy-five thousand years ago and was called the Toba catastrophe.

Somewhere in our deep past, a giant volcanic eruption—most probably of Mt. Toba on the island of Sumatra—created the volcanic version of a nuclear winter. The supercolossal explosion was the equivalent of one trillion tons of TNT, and sent volcanic debris more than twenty-five miles into the stratosphere. The resulting ash cloud covered much of the world, causing temperatures to drop as much as 5 degrees and possibly triggering an ice age. The number of humans, already relatively small, dwindled to approximately fifteen thousand, spread throughout Africa and southwest Asia. Yet those fifteen thousand managed to regroup and repopulate Africa within a few tens of thousands of years, and to move out into the rest of the world thirty thousand years later.

Population biologists talk of something called a minimum viable population, which is the smallest number of individuals that can survive "in the wild." For terrestrial vertebrates, that number is around four thousand. Of course, more individuals are always better for the species, as long as the food holds out, because they bring more genetic diversity into the population. As long as there are at least four thousand souls in a single population group, then Hera's children should have survived.

i. Sym = together, bio = life; a symbiotic relationship is one in which at least two different organisms live together, usually (but not always) providing a benefit to both creatures. For example, we provide cats with shelter and a steady food supply; cats provide us with rodent control and aloof companionship.

ii. Specifically, the sperm's mitochondria are marked for elimination by the egg's cytoplasmic destruction machinery. Talk about being a ballbuster.

iii. Incidentally, the use of the term "Eve" is not meant to indicate that she was the only human female of the time, simply that she was mother to us all.

iv. The article that Angel Six reads over Ron Moore's shoulder purports to say Tanzania.

v. Or do we? Angel Baltar gleefully said, "Along with her Cylon mother . . . and human father!" It's totally reasonable to think that once the fleet settled on Earth, other Cylon-Colonial pairs had offspring in the same generation as Hera, perhaps even Six and Baltar. Imagine if their child was Mitochondrial Eve!

Saturday, 30 October 2010

Johnald's Fantastical Daily Link Splurge

Johnald's Fantastical Daily Link Splurge

Space Tourism’s Rubbery Rockets May Spur Climate Change

Posted: 29 Oct 2010 03:38 PM PDT

Suborbital spaceflights that rely on rubber-based rocket fuel could shrink icecaps, alter the ozone layer and affect global temperatures, according to a new study.

Yet the study authors' assumptions about the number of rocket launches per year and the chemistry of rocket exhaust have raised questions about their conclusions among space-tourism companies and climatologists not involved in the study.

Atmospheric scientists who performed the research probed the effects of belching ultrafine soot high into the stratosphere, where — unlike the troposphere below it — there isn't rain and wind to quickly filter soot out of the air. Rubber-based rocket fuel burned with nitrous oxide is the preferred propellant of the burgeoning space-tourism industry, and chemists suspect such hybrid engines emit sooty black carbon. Closer to Earth, the stuff has been shown to soak up extra radiation from the sun and contribute to climate change.

"This study was a natural extension of the climate-research community gaining a greater and greater appreciation of black carbon in terms of global radiative forcing," said Martin Ross, an atmospheric scientist at The Aerospace Corporation in El Segundo, California, and leader of the research funded in part by his employer. "Soot is a very large issue in the troposphere," Ross said, but its behavior isn't well-understood at higher altitudes.

To model the effects of space tourist launches on the Earth's atmosphere, Ross and his colleagues used the open-source Whole Atmosphere Community Climate Model Version 3, or WACCM3, one of the most-advanced computer models available to study impacts to global climate.

They ran two supercomputer-powered simulations for two weeks, one as a control and another modeling the impact of 1,000 suborbital flights per year for the next four decades. That many flights, according to the study, would annually deposit more than 1.3 million pounds of soot into the stratosphere.

"We looked at the stated business plans from corporations that are planning to build vehicles for space tourism," Ross said. "If you go to their websites, they'll say things like, 'we plan to launch once per day.' We found 1,000 per year is well within stated objectives of the industry."

On average, according to the simulation, the soot pushed polar ocean temperatures up by 1.8 Fahrenheit degrees, melted 5 to 15 percent of sea ice and depleted 1 percent of tropical ozone (while boosting polar ozone by 6 percent).

"We're not making any particular prediction about any system, just taking reasonable guesses at what soot from a hybrid rocket engine looks like and what the launch industry will do in the future," Ross said. "When we put that into a gold-standard model, the effect on the Earth is surprisingly large. In short, we think black-particle carbon from rockets is something that deserves attention."


Their assumptions may not be perfect, said Gerald North, an atmospheric scientist at Texas A&M University who was not involved in the study, but the measured effect is significant enough to warrant further investigation.

While they make assumptions about some unknowns, such as the behavior of soot at high altitudes, North said, "they're careful in expressing this is not the last word" and are "inviting others to take a look."

Ross and Michael Mills, an atmospheric chemist at the National Center for Atmospheric Research in Colorado and a co-author of the study, said that's precisely what the research team sees as the next step. In particular, getting a handle on what's in the emissions of different types of rocket plumes.

"There are few direct high-altitude measurements of rocket plumes. We really need to get aircraft in those and get measurements of soot and other particles," Mills said. "Until then, the sophistication of our models is limited."

To do just that, Ross said The Aerospace Corporation is planning a workshop to bring together under one tent all the stakeholders in science, rocket engineering, space-tourism companies and the government agencies.

"We need to get these players together and exchanging ideas, then ask the policy people to figure out what to do, if anything, with the information," Ross said.

"I think we and others in the industry welcome the opportunity to talk about all of these issues," said George Whitesides, CEO of Virgin Galactic, a space-tourism company that's planning to use hybrid rocket engines. Whitesides wasn't without reservations about the study and its conclusions, however.

"Frankly, I have to admit I wished they talked to us before putting out a paper, but that's OK. Climate issues are deeply important to Virgin, and we take them very seriously," Whitesides said.

Part of the reason the company chose the hybrid rocket design for its SpaceShipTwo was "because of its significantly lower environmental impact than other designs." Whitesides also said 1,000 space tourist launches per year is "guesswork," because the industry is privatized and young.

"I think as we look at this more, we'll find the impact will be far smaller than that set out in the paper," he said. "In any case, I welcome the conversation."

Whether or not peaceable collaborations ensue, both Ross and Mills expressed that carbon soot is something the nascent space tourism industry can't ignore.

"This shows that a new kind and level of emission being deposited directly into the stratosphere could have a significant effect," Mills said. "Companies need to proceed with developing their systems with full knowledge of consequences on the planet."

Images: 1) Virgin Galactic's SpaceShipTwo (center) attached to WhiteKnightTwo. Flickr/Jeff Foust. 2) The average predicted changes after one decade in the ozone layer (top) and regional temperatures (bottom) caused by 1,000 hybrid rocket launches per year for 40 years. Ross et al. 3) Average seasonal soot deposition, in grams per square meter, in the stratosphere predicted by Ross et al.'s simulation. Ross et al.

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Engineer Finds Secret to Growing Ridiculously Huge Pumpkins

Posted: 29 Oct 2010 11:34 AM PDT

Linus was right after all. Not only does the Great Pumpkin exist, but scientists have figured out how he manages to get so big.

In a sort of self-perpetuating cycle, the bigger a gourd gets, the more physical stress it experiences — thus triggering giant pumpkins to grow even more.

"Their weight generates tension, which pulls cells apart and accelerates growth," says David Hu, a mechanical engineer at the Georgia Institute of Technology in Atlanta, whose team has submitted a paper to a peer-reviewed journal.

Such research doesn't just illuminate the story behind record-setting pumpkins, like the nearly 1,811-pound behemoth recognized this month by Guinness World Records. The work also addresses larger questions of plant development, such as how tissues cope under stress, Hu says.

All giant pumpkins are grown from a single strain, the Atlantic Giant seed, which has a longer growing season than normal pumpkins. The fruits start out round, but once they get to about 220 pounds, they begin to flatten under their own weight, eventually resembling a giant deflated sack.

Wondering how the monsters got so large without splitting, Hu's group squashed regular-sized gourds in the lab to see how much stress they could take before rupturing. The researchers then created a mathematical model of how the fruits could accommodate the stress.

The model predictions matched observations of giant pumpkin dimensions sent in by 50 farmers from around the country. Hu says that plastic, or rreversible, deformation allows the fruit to distribute stresses so it can grow — sometimes adding 50 pounds a day — without breaking.

The New York Botanical Garden, where the world's biggest pumpkin will be carved this weekend, says that a 2,000-pound pumpkin could be grown within the next few years.



Image: Flickr/martine266

Videos: Vimeo/David Hu/Georgia Tech

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The Making of a Mind-Blowing DIY Sun Photo

Posted: 29 Oct 2010 10:42 AM PDT

This stunning portrait of the sun spread like hot plasma all over the internet yesterday. spoke with artist and astrophotographer Alan Friedman to find out how he made it.

Friedman shoots the sky from his backyard in downtown Buffalo, New York. That means the usual celestial candidates — galaxies, nebulae, distant star clusters — are washed out by the glow of the city. But the sun is fair game, as long as the sky is clear and turbulence-free.

"I don't care about sky glow at all," Friedman said. "I just need atmospheric steadiness."

On Oct. 20, Friedman hooked his telescope to a hydrogen-alpha filter, which selects a tiny slice of the visible light spectrum. Hydrogen, the chief component of the sun, radiates strongly in this deep-red light, letting both the sun's outer layers and the feathery filaments that extend away from the disk show up in sharp detail (see photos below).

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Until a few years ago, Friedman says, this kind of filter was only available for research-grade telescopes. They're still not cheap — he got his for around $5,000. Friedman's telescope, which he calls Little Big Man, is small but mighty. The light-collecting aperture is about 3.5 inches wide.

Instead of just snapping a photo, Friedman took 90 seconds of streaming video and selected only the sharpest frames. Each exposure captures about 900 frames, but Friedman threw all but 200 of them away.

In two separate 90-second videos, Friedman zoomed in on the edge of the solar disk to capture wisps of gas arcing along loops of the sun's magnetic field, plus sunspots and the detailed churning of the sun's atmosphere.

Then he inverted the images, making all the dark spots light and the light spots dark. This is an unusual thing for solar photographers to do, he says, but it gives a more authentic view of the sun.

"It's hard to capture the feeling the eye would get looking at the sun without doing that," he said. "It gives a sense of the sun that's both powerful and closer to what you would actually see."

Friedman's camera shoots in black and white, so he also had to add in some color. Although generally he tries to keep his astrophotos as true to science as possible, he took some artistic liberties with the color choice.

"This was a Halloween image," he said. The sun couldn't be anything but orange.

Images: Alan Friedman

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Stone Agers Sharpened Skills 55,000 Years Earlier Than Thought

Posted: 29 Oct 2010 08:20 AM PDT

Stone toolmakers living in southern Africa 75,000 years ago pushed the cutting edge in more ways than one. These intrepid folk sharpened the thin tips of heated stone spearheads using a forceful technique previously dated to no more than 20,000 years ago, a new study finds.

This stone toolmaking method, called pressure flaking, was invented and used sporadically in Africa before spreading to other continents, according to a team led by archaeologist Vincent Mourre of the University of Toulouse-Le Mirail in France. Having a flexible repertoire of toolmaking methods aided the survival of modern humans who left Africa beginning around 60,000 years ago, the scientists propose in the Oct. 29 Science.

The finding fits with the idea that symbolic art, rituals and other forms of modern human behavior developed gradually over hundreds of thousands of years, not in a burst of cultural innovation marked by cave paintings and other creations that appeared after 50,000 years ago in Western Europe.

Excavations of sediment dated to 75,000 years ago in South Africa's Blombos Cave produced stone artifacts displaying signs of pressure flaking, Mourre and his colleagues say.

"The Blombos evidence for pressure flaking is the oldest we know," says anthropologist and study coauthor Paola Villa of the University of Colorado Museum of Natural History in Boulder.


Blombos Cave and nearby sites of comparable age previously yielded engraved pigment chunks, decorated ostrich eggshells and heat-treated stone artifacts.

Southern Africans occasionally made items with symbolic meanings and used special forms of toolmaking beginning 100,000 years ago or more, Villa suspects. These practices flourished in and out of Africa starting about 40,000 years ago, in her view.

Pressure flaking consists of trimming the edges of a finished tool by pressing with a bone point hard enough to remove thin slices of rock. This process creates the narrow, evenly spaced grooves found on flint tools from Europe's 20,000-year-old Solutrean culture and prehistoric Native American groups.

Wider, more irregular grooves characterize 36 pressure-flaked Blombos tools, which were made from silcrete, Villa says. This rock, a silica-rich material, is of lower quality than flint and requires heating to ready it for pressure flaking.

Villa and her colleagues identified glossy areas on silcrete tools at Blombos that, they surmise, formed when the stones were pre-heated for pressure flaking. Other marks on the artifacts indicated that they had been attached to handles, probably as spearheads.

By pressure flaking preheated replicas of the Blombos finds made from silcrete and collected near the South African cave, Mourre was able to reproduce marks resembling those on the ancient artifacts.

Toolmakers likely used pressure flaking by 100,000 years ago in East Africa, remarks archaeologist John Shea of Stony Brook University, New York. Several sites there contain stone artifacts, many made from obsidian, that deserve close analysis for pressure-flaking marks, Shea says.

Shea, an expert at making replicas of Stone Age tools, notes that pressure flaking can be taught in 30 minutes to a novice. "It is, literally, so easy a caveman can do it," he says.

Pressure flaking doesn't add much sharpness or strength to a cutting instrument, Shea adds. Blombos toolmakers probably employed this technique to advertise their skill or to denote users' social identity, he proposes.

Archaeologist Curtis Marean of Arizona State University in Tempe calls the evidence for pressure flaking at Blombos "suggestive but not completely convincing." Further work needs to confirm that pressure flaking of replicated silcrete artifacts consistently produces marks like those on the Blombos finds, Marean asserts.

Knowledge of pressure flaking doesn't imply any special mental or toolmaking abilities, he remarks. Like Shea, Marean regards pressure flaking as a simple way to finish shaping tools made from certain types of stone.

"If the authors are correct that pressure flaking occurred at Blombos Cave, the result is important in that that it extends the time range of the technique," Marean says. "But it's not game-changing in our understanding of the origins of complex cognition."

Images: Copyright Science/AAAS 1) Researchers say that evidence of a special sharpening technique appears near the tips of 75,000-year-old stone artifacts from a South African cave, such as the find shown here. Previous signs of this toolmaking method dated to no more than 20,000 years ago. 2) A Still Bay bifacial point from Blombos Cave made on silcrete and finished by pressure flaking, mainly at the tip.

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Friday, 29 October 2010

Johnald's Fantastical Daily Link Splurge

Johnald's Fantastical Daily Link Splurge

World’s Most Precise Clocks Could Reveal Universe Is a Hologram

Posted: 28 Oct 2010 04:11 PM PDT

Our existence could be coded in a finite bandwidth, like a live ultra-high-definition 3-D video. And the third dimension we know and love could be no more than a holographic projection of a 2-D surface.

A scientist's experiment, now under construction in Illinois, will attempt to test these ideas by the end of next year using what will be two of the world's most precise clocks.

Skeptics of a positive result abound, but their caution comes with good reason: The smallest pieces of space, time, mass and other properties of the universe, called Planck units, are so tiny that verifying them by experiment may be impossible. The Planck unit of length, for example, is 10 trillion trillion times smaller than the width of a proton.

Craig Hogan, a particle astrophysicist at Fermilab in Illinois, isn't letting this seemingly insurmountable barrier stop him from trying.

Hogan is following through on a radical idea to confirm Planck units with two of the most precise clocks in the world. Deemed holometers, each L-shaped laser interferometer will have two perpendicular, 131-foot-long arms to scan for pixelation in the very fabric of space and time. If it's there, two laser beams (split from a single source) that run through the arms won't hit a detector at the same time.

"What we're looking for is when the lasers lose step with each other. We're trying to detect the smallest unit in the universe," Hogan said. "This is really great fun, a sort of old-fashioned physics experiment where you don't know what the result will be."


The two holometers, now being built in an earth-covered tunnel on Fermilab's prairie-covered campus, will initially be stacked almost on top of one another to listen for the same Planck-scale "noise." Once the machine is calibrated and environmental interference is accounted for, Hogan says it should only take a matter of minutes to see if the devices simultaneously see it.

Should Hogan's team detect something significant, they will then separate the machines and run the experiment all over again. If the noise they measure next isn't correlated between the machines, it could be the calling card of a limit to space-time's resolution.

Inspiration for the holometer came from such a noise picked up by an experiment called GEO600. Designed to detect gravity waves — ripples in space-time caused by things like colliding black holes — the machine is a laser interferometer like the holometer will be, yet has arms 15 times longer and a lower-frequency laser source (to be sensitive to gravity waves, if they exist).

Experimental physicist Hartmut Grote, of the Max Planck Institute in Germany, said he and his colleagues at GEO600 have been unable to pinpoint the source.

"In the past, [Hogan] became a little bit driven, even excited for some time, that this noise could be a result of the holographic principle," Grote said.

The holographic principle, derived from weirdness theorized to occur at the boundaries of black holes, says reality could be a 3-D projection of a 2-D plane of information. It's much the same way a hologram printed on a credit card creates the illusion of a 3-D object but, as Hogan explained, we can't perceive the 2-D surface.

"We could be living inside that 3-D projection, with the truer vision of it as a 2-D sheet hidden by scale," Hogan said.

Ultra-precise devices such as laser interferometers might be able to detect noisy fluctuations in the projection, which Grote says might "blow up" the pixelation to a larger, detectable size. Yet Grote suggests Hogan's holometers, which are slated to be finished in a year, may be too late if progress with GEO600 continues on-schedule.

"We are not at the point where we can verify the noise we discovered is holographic, but we can falsify it as soon as our instrument is more sensitive than the limits of Hogan's theory," Grote said. "I'm confident we will reach that point over the next half of a year and find the source of the noise."

Hogan maintains his cheeriness for the endeavor, even if much of the physics community remains skeptical. But Grote says Hogan has good reason to be upbeat.

"I think it's a reasonable design to measure this effect, even though I think it's unlikely he's going to measure something," Grote said. "If anything happens, he'll put to rest another exotic theory about the universe."

If he does find a limit to the universe's resolution by exploiting the cosmos' possible holographic underpinnings, however, Grote said it will make waves.

"It would be a very strong impact to one of the most open questions in fundamental physics," he said. "It would be the first proof that space-time, the fabric of the universe, is quantized."

Via: symmetry breaking

Images: Fermilab. 1) A schematic plan of the holometers. 2) Sam Waldman, a physicist at MIT, working on the holometer's first arm. 3) The tunnel housing the first arm of the experiment. 4) A chart showing where, if the holographic principle holds true, the holometer is just beyond the threshold of detecting holographic noise (GEO600 is on the border).

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Spiral Galaxy Study Yields Super Sharp Images

Posted: 28 Oct 2010 03:00 PM PDT

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Six spiral galaxies were stripped bare by an infrared camera at the Very Large Telescope in Chile.

By observing in wavelengths of light beyond what the human eye can see, the camera, called HAWK-I, can peer through the gas and dust that obscure galaxies' spiral arms. This makes it ideal for studying how many stars make their homes there.

The six galaxies are part of a study of spiral structure led by Preben Grosbøl at the European Southern Observatory, who is investigating how stars form into such perfect spiral patterns.

The galaxies represent three different classes of spiral shapes. Three of them — dubbed NGC 5247, NGC 4030 and NGC 2997 — are simply designated as spiral galaxies. One galaxy, NGC 1300, is a "barred spiral," with two arms extending from a prominent central bar. Another, NGC 1232, is an "intermediate spiral," lying somewhere between barred and unbarred galaxies. And NGC 4321 (also known as Messier 100) is a "grand spiral," featuring several well-defined, tentacle-like spiral arms.

This growing galactic gallery shows the diversity of galaxy shapes with unusual clarity.

Images: ESO/P. Grosbøl

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Video: Magnetic Twister Erupts on Sun

Posted: 28 Oct 2010 02:35 PM PDT

NASA's Solar Dynamics Observatory caught an enormous plasma twister erupting on the surface of the sun Oct. 28.

The explosion was triggered by a tangled coil of magnetism that suddenly untwisted, acting like a loaded spring and hurling solar matter into space. At its peak, the twister towered more than 217,000 miles above the surface of the sun.

Luckily, the fragments of plasma flung into space were not headed toward Earth, where they could have caused a magnetic storm. Now that the twister has relaxed, it probably won't erupt again — though other sunspots are gathering energy and could produce medium-sized solar flares.



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Sleeping Mars Rover Finds Evidence of Liquid Water

Posted: 28 Oct 2010 01:12 PM PDT

The soft Martian soil that ensnared the rover Spirit holds evidence that liquid water still trickles below the planet's surface. But this serendipitous discovery may be Spirit's last.

Spirit's wheels broke through the crust of a sand pit called "Troy" in April 2009, after five years spent mostly exploring a region called Home Plate. NASA officially gave up on trying to extract the rover in January.

But the soil exposed by Spirit's spinning wheels carries clues that Mars may still be wet. The newly exposed surface layers include minerals thought to be hematite, silica and gypsum, which don't dissolve easily in water. But layers of iron sulfate minerals, which do dissolve easily, lie centimeters below the crust.

These layers suggest water, maybe in the form of frost or snow, seeped into the ground relatively recently and carried the soluble minerals deeper into the soil. The seepage could have happened during cycles in Mars' history when the planet tilted further on its axis.

None of these soluble minerals are exposed at the Martian surface, which indicates the soil interacted with water recently, and probably continuously. Because the Martian surface is constantly being sculpted by wind, these layers would have eroded away if they were laid down long ago.

Water could also have come from fumaroles or hot vents beneath the surface, the rover team reports in the Journal of Geophysical Research.


"On Earth, fumaroles and hydrothermal systems provide the environmental conditions, water, nutrients and energy sources needed to sustain robust microbial communities," the team wrote. A prime example is the acidic, iron-rich hot springs in Yellowstone National Park.

"It seems likely that the region in and around Home Plate may have likewise supported a habitable environment," the team wrote. Although there may not have been enough water to sustain life for long.

In 10 attempts to break free, Spirit only managed to drive 13 inches backwards through the soft soil before NASA gave up in January. Spirit shut down completely on March 22 to hibernate through the Martian winter. If the rover wakes up again when Martian spring arrives next month, there will be fresh soil to explore. The researchers also plan to take advantage of Spirit's immobilization to investigate whether Mars's core is liquid or solid by precisely tracking the rover's radio signal.

But Spirit has sat through colder temperatures this winter than it ever experienced, and its solar panels were stuck facing away from the sun. It may not wake up. Scientists are crossing their fingers, but not holding their breath.

Image: NASA/JPL-Caltech/Cornell University

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Your Fingers Know When You Make a Typo

Posted: 28 Oct 2010 12:03 PM PDT

The brain uses two different checks to guard against sloppy copy, a new study finds. By using a doctored word processor to sneak errors into typed words and surreptitiously fix typists' real errors, researchers teased apart the various ways people catch their own mistakes. The study, published in the Oct. 29 Science, highlights the complexity of performance monitoring.

Psychologist Gordon Logan and his colleague Matthew Crump of Vanderbilt University in Nashville recruited skilled typists — people who typed more than 40 words a minute using all of their fingers. These subjects were able to type a paragraph about the merits of border collies with over 90 percent accuracy.

As the typists pecked away, researchers introduced common typing errors into about 6 percent of the words that appeared on a screen (changing sweat to swaet, swerat or swet, for instance). The program also corrected about 45 percent of the typists' true errors.

In questionnaires after the typing test, subjects by and large took the blame for the introduced errors and took credit for the researchers' corrections. No matter what he actually typed, when the typist saw that the word on the screen matched the word he had intended to type, he assessed his own performance as accurate.

But the speed of the typists' keystrokes revealed something else. After hitting the wrong key, a typist's fingers slowed down for the next keystroke, even if the researchers sneakily fixed the error so that the typist didn't notice it. In these cases, a typist wasn't explicitly aware of the mistake, but the brain's motor signal changed nevertheless.


Logan says that this change in timing reflects a kind of automatic assessment of performance. "The body is doing one thing and the mind is doing another," he says. "What we found was that the fingers knew the truth."

Many psychologists thought that the mind was capable of detecting errors in several ways, but "nobody had pinned it down," says cognitive neuroscientist Jonathan Cohen of Princeton University. "Here, they developed a very clever set of experiments to tease the types of system apart."

The results may reveal a hierarchical method of error correction — with a "lower" system doing the actual work and a "higher" system assigning credit and blame, Logan suggests. These multiple layers of control may be evident in tasks such as playing music, speaking and walking to a destination, Logan says. As a man heads toward a new restaurant, his brain is noticing landmarks and keeping on the right course. Meanwhile, his feet steadily plod along, navigating the terrain automatically.

Whether the two types of error-catching systems operate in tandem or one is subservient to the other isn't yet clear, Cohen says. Having the automatic, fingers-level system answer to the higher system "has a sort of intuitive appeal," Cohen says, "but whether that idea is a convenience until we have a better idea or it's true remains to be seen.""

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Odds of Finding Earth-Size Exoplanets Are 1-in-4

Posted: 28 Oct 2010 11:00 AM PDT

Nearly one in four sun-like stars should host an Earth-mass planet, according to a new census.

The finding is the first quantitative measurement of the frequency of planets of various masses in the galaxy.

"It's a landmark paper," said exoplanet expert Josh Winn of MIT, who was not involved in the new study. "There's been all this talk, that low-mass planets like the Earth are very common. But this is the first time it's been documented."

The study, published in the Oct. 29 Science, also found plenty of planets in a mass range that astronomers expected to be empty, which may prompt an overhaul of planet-formation models.

Using the Keck Observatory in Hawaii, astronomer Andrew Howard of the University of California, Berkeley and colleagues watched 166 sun-like stars for the telltale wobbles induced by a planet's pull.

Unlike previous surveys, Howard and colleagues were just as interested in stars that lack planets as stars that host them. To avoid biasing the study toward planet-bearing stars, the team selected the nearest and brightest stars in the 120,000-star Hipparcos Catalog.

"It's hard to write a telescope proposal that says, 'We want to look at these stars because we think they don't have planets,'" Howard said. "But that's what we had to do."


Over the course of five years, the team observed each star at least 20 times in search of planets that have masses between 3 and 1,000 times the Earth's mass and that orbit close to their stars.

They found 33 planets around 22 of the stars, some of which had already been discovered and reported by other groups, and 12 candidate planets that still need to be confirmed. Because some stars were observed more often than others, the team included a "missing-planet correction" to account statistically for planets that would probably show up with more observations.

None of these planets was actually the same mass as Earth. Astronomers' instruments aren't yet sensitive enough to detect such small worlds.

"But what we can do is extrapolate," Howard said. "It involves a little bit of speculation, but we're comfortable with that uncertainty."

In general, small planets turned out to be much more common than large ones. The researchers extended that trend down to planets about half Earth's mass.

They found that about 23 percent (give or take about 10 percent) of sun-like stars should have a planet between half and twice the Earth's mass orbiting very close in, about a quarter of the distance from the Earth to the sun. That distance would make the planets far too warm for liquid water. But because planets tend to be more abundant farther from their stars, Howard thinks there should be even more Earth-mass planets in cooler orbits where liquid water is stable.

"I wouldn't be surprised if the true number [of stars hosting Earth-mass planets] is one in two, or one in eight — but I'm almost sure it's not one in 100," he said. "That's a really big improvement on our knowledge."

Surprisingly, the observations also showed a lot of planets between 5 and 30 times Earth's mass, a range that theoretical models of planet formation predicted should be so empty it earned the name, "the planet desert."

"We showed that the desert is in fact closer to a tropical rain forest," Howard said.

The new numbers are a windfall to researches like Winn, who are involved in designing the next generation of planet-hunting telescopes.

"It sets our expectations much more clearly than they were last week," he said. "We were just guessing, to see how to design the instrument. Now we have some much more solid numbers to put in."

Exoplanet expert Sara Seager of MIT, who was not involved in the new study, noted that this is one of the first exoplanet papers that doesn't focus on just one planet or one system of planets.

"Exoplanet [research] is moving from single-planet characterization to statistics," she said. Thanks to the statistical treatment, Seager is more willing to accept uncertainties in Howard's analysis.

"You might not have confirmation of every individual planet, but that's OK," she said. "That shouldn't stop you from making general statements."

The study also prepares the way for the deluge of planets that should come from the Kepler Space Telescope in the next few years, she says. "We want the world to accept things from Kepler, but they have to be primed to believe that statistics are OK."

Image: 1) WMKO 2) NASA/JPL-Caltech/UC Berkeley

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Climate Change Blurs Definition of Native Species

Posted: 28 Oct 2010 09:31 AM PDT

GLACIER NATIONAL PARK, Montana — As climate changes, some environments are becoming hostile to the flora and fauna that long nurtured them. Species that can migrate have begun to move into regions where temperatures and humidity are more hospitable. And that can prove a conundrum for officials charged with halting the invasion of non-native species, notes Jon Jarvis, a biologist who for the past year has headed the National Park Service.

One problem: What's native? Species move at will as conditions change. What's native in one century may be gone five generations later. Newly arrived species, meanwhile, may be environmental refugees.

"Policies that are currently in place view those [immigrants] as exotics," Jarvis says — invading homesteaders that should, at all costs, be evicted. But such species may be on the move simply "because this is their last efuge," he points out. "So we have to rethink that policy and how we respond to new species that are coming into our parks."

Each new immigrant has the potential to radically change the neighborhood — welcoming an influx of new predators and parasites, altering soil nutrients and porosity, even changing the amount of moisture and sunlight that reaches ground dwellers. And most of these changes can't be fully anticipated in advance.

Bottom line: With these migrations "we are going to be faced with very fundamental, difficult questions," Jarvis notes: Are the new arrivals weeds or endangered species to be welcomed with open arms?

One example — peccaries.


Jarvis was driving down the southern rim of Grand Canyon National Park a few months ago, when a group of piglike peccaries — also known as javelinas — crossed the road in front of him. The park's superintendent volunteered to Jarvis that "javelinas didn't used to be here." Although an American native, these animals are moving into novel, more-northerly locations, Jarvis observes. "And I think this is going to be true for a lot of species."

There is even talk, he says, about whether to help resettle some species into what for them will be novel sites. It may be the only way to ensure that threatened species survive into the next century, Jarvis told several dozen reporters who were touring Glacier National Park earlier this month.

For instance, much as they might like to, giant sequoias are not going to migrate. They have been literally rooted to their current ecosystem for millenniums. Today, he notes, "they are as iconic to the Sierra as glaciers are to Glacier [National Park]." But the sequoias are feeling the heat and not liking it.

So, he asks: "Are we, as a society, to move them — to plant them in the Cascades?" Actually, he acknowledges, "We're not quite ready to answer such questions. But we're beginning to have to face them."

Image: Peccaries

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