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Top 10 Science Stories of 2015

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It’s been a busy year for scientists: medical breakthroughs; newly discovered human ancestors; genes and neurons; Earth’s troubled species; and enticing findings from Mars, Pluto, and beyond. Here are 10 science advances that made a big impact in 2015. 

1. WE GOT UP CLOSE AND PERSONAL WITH PLUTO.

After a 9.5-year, 3-billion-mile journey, NASA’s intrepid New Horizons spacecraft finally reached Pluto in July, sending back high-resolution images of the dwarf planet and its moon, Charon. At its closest approach, the craft passed within 7800 miles of Pluto’s surface—close enough to reveal bizarre ice mountains and vast, crater-free plains, seemingly divided into “cells” dozens of miles wide. There’s evidence of geological activity within the last 100 million years—a mere eye-blink compared to the age of the solar system—which came as a surprise to scientists, who imagined Pluto to be a geologically “dead” world. Charon, meanwhile, has cliffs that run for hundreds of miles, and canyons more than six miles deep. The findings will keep planetary scientists busy for years.

2. WE OPENED THE DOOR TO CUSTOM DNA.

An organism’s development is governed by its DNA—but what if you could manipulate that DNA at will? The era of custom “gene editing” now looms on the horizon, thanks to a tool known as CRISPR-Cas9, which allows researchers to “swap out” sections of a genome faster and more cheaply than ever before. Earlier this year, scientists developed gene-edited mosquitos that are resistant to malaria and gene-edited African pigs that are immune to swine fever; the FDA, meanwhile, recently approved a fast-growing, gene-edited salmon for human consumption.

Are genetically engineered humans next? Scientists in China have already done the first experiments on human embryos, in a bid to correct faulty genes that cause disease. The embryos in those studies were non-viable, but even so there’s been a storm of controversy. Some argue in favor of human gene modification, in the hope of engineering human beings with less susceptibility to devastating illnesses such as cancer and dementia—while others see any such research as the start of a slippery slope leading to a world divided between genetic haves and have-nots.

3. WE MAY HAVE FOUND A NEW MEMBER OF THE HUMAN FAMILY TREE.

Berger et al. ineLife.

Pieced together from 1500 bones found deep in a cave near Johannesburg, South Africa, Homo naledi—claimed to represent a new species of human ancestor—caused a sensation when the finding was announced in September. (“Naledi” means “star” in Sesotho, one of South Africa’s official languages.) Its bones tell a complicated story. The small skull and ape-like shoulders suggest it may be among the earliest members of the human family tree, while the shape of the feet and ankles indicate it walked upright. And yet the highly curved fingers hint at the tree-climbing prowess of its ancestors.

But is it really a new species? Some skeptics believe the bones could belong to early members of Homo erectus, a well-documented human ancestor that lived from about 1.9 million years ago to about 70,000 years ago—or even an isolated offshoot of Homo sapiens. It would help if we knew exactly when Homo naledi flourished; unfortunately, scientists haven’t been able to date the bones yet.

4. WE DISCOVERED THAT WE MAY BE CAUSING A SIXTH MASS EXTINCTION.

Over the past 450 million years, the Earth has witnessed five “mass extinction events”—catastrophes in which an asteroid impact or volcanic activity triggered rapid climatic change and a dramatic loss of biodiversity. The most severe of these was the event that killed off the dinosaurs—and three-quarters of all species—some 66 million years ago. Scientists believe we’re now on the brink of a sixth such mass extinction event—only this time, the culprit is human activity. In a study published in the journal Science Advances in June, biologists found that our planet is losing animal species at 20 to 100 times the average “background” rate, and that the rate is increasing. “The smoking gun in these extinctions is very obvious, and it’s in our hands,” Todd Palmer, a biologist at the University of Florida and a co-author of the study, told the Washington Post

5. WE PENETRATED THE BLOOD-BRAIN BARRIER FOR THE FIRST TIME.

Injecting drugs into the body is routine—unless you’re targeting the brain, which is protected by the “blood-brain barrier,” a film-like coating that surrounds the blood vessels in the brain. The barrier prevents harmful substances from entering the brain—but also stands in the way of certain treatments (for example, chemotherapy drugs targeting brain tumors). In November, doctors in Toronto used tightly focused ultrasound waves to penetrate the barrier for the first time. The technique could pave the way for the treatment of an array of illnesses, from brain cancer to Alzheimer’s disease. 

6. WE FOUND LIQUID WATER ON MARS.

Getty Images

Mars, with its many similarities to Earth, has long been the most enigmatic planet in our solar system—and it became even more beguiling in September, when NASA scientists announced that they’d found evidence for flowing water on the planet’s surface. Images from the Mars Reconnaissance Orbiter reveal dark streaks that appear during the Martian summer, likely the result of seasonal “flows.” A caveat: the water is briny and extremely salty, and scientists are far from certain that it’s capable of supporting life. And while it would be great to go there (or send a robotic ambassador) for a close-up view, there’s a very real danger of contaminating the area with microbes from Earth.

7. WE CONFIRMED THAT “SPOOKY ACTION AT A DISTANCE" IS REAL.

It’s one of the most bizarre features of the quantum world: The notion that two particles, even if they’re far apart, can be “entangled” quantum mechanically. When two particles are entangled, measuring the properties of one particle instantly gives you information about the other, regardless of the distance between them. The notion of entanglement dates back to a paper written by Einstein and two colleagues in the 1930s, although he later dismissed the idea as “spooky action at a distance.” But beginning in the late '70s, ever-more sophisticated experiments suggested entanglement is real. In October, physicists in the Netherlands managed to entangle two electrons almost a mile apart—and they say they’ve ruled out all of the loopholes which made earlier experiments inconclusive. And while it all may sound pie-in-the-sky, scientists say that the research could eventually lead to the development of ultra-fast “quantum computers,” with potentially game-changing applications in medicine, cryptography, and artificial intelligence.

8. WE IMPLANTED FALSE MEMORIES IN MICE.

iStock

We think of memories like pages in a scrapbook, or pictures in a photo album, but in practice, our memories are often wrong. “False memory syndrome” is now recognized as a real phenomenon in the scientific literature, and psychologists are eager to learn more about how erroneous memories form. Animal studies may shed some light. In March, neuroscientists in France described how they were able to implant false memories into mice while the animals slept. They used electrodes to directly stimulate specific nerve cells within the brain, causing the mice to associate certain locations with rewards. After waking, the mice “remembered” those associations, spending more time in the locations where they (incorrectly) recalled receiving a reward. The researchers hope their work will help explain how false beliefs form in humans.

9. WE THEORIZED THAT DARK MATTER WIPED OUT THE DINOSAURS.

We don’t usually think of events in deep space influencing life on Earth—after all, astrology was debunked centuries ago. But if physicist Lisa Randall is right, there may be a subtle but important connection between an exotic form of matter that permeates the universe, and the evolution of life on our blue-green world. In her book Dark Matter and the Dinosaurs, Randall suggests that a thin disk of dark matter—a kind of matter that responds to gravity, but not to light—might periodically perturb the orbit of comets at the far edges of our solar system. That might be what happened 66 million years ago, when a wayward comet is believed to have slammed into the Earth, triggering catastrophic climate change and dooming not only the dinosaurs but three-quarters of all species. It’s a controversial theory, but it could gain support, Randall says, if we can detect the gravitational influence of the alleged dark-matter disk. Read an excerpt from Dark Matter and the Dinosaurs on Science Friday.

10. WE FOUND A WEIRD STAR—OR MAYBE E.T.? (MAYBE NOT.)

Artist's representation of a crumbling Dyson sphere orbiting KIC 8462852. Image credit: Danielle Futselaar // SETI International

You wouldn’t think it’s anything special from its name—KIC 8462852—but the peculiar star, located about 1500 light-years from Earth, set the Internet abuzz in September when it was suggested that it might be home to an advanced alien civilization (“might” being the key word, of course). Data from the Kepler space telescope showed that the star undergoes strange variations in brightness over time. Kepler is specifically designed to detect planets that may periodically pass in front of a star, causing it to dim—but KIC 8462 displayed a more unusual pattern, with more substantial dimming at irregular intervals. A swarm of comets was said to be the most likely explanation. But one of the astronomers also suggested the possibility of an “alien megastructure”—perhaps some variation of the “Dyson sphere,” a vast artificial structure that an advanced civilization might build surrounding a star, popularized by physicist Freeman Dyson in the 1960s.

Later, radio astronomers aimed the Allen Telescope Array in California at the star, just in case it was emitting alien chatter. It was not. The latest thinking is that it’s probably comets after all. The lesson? When it’s a choice between aliens and something else, it’s always been something else (so far), and that’s most likely the case this time. But for getting people’s attention, little green men beat icy snowballs every time. 

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Man Buys Two Metric Tons of LEGO Bricks; Sorts Them Via Machine Learning
May 21, 2017
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iStock // Ekaterina Minaeva

Jacques Mattheij made a small, but awesome, mistake. He went on eBay one evening and bid on a bunch of bulk LEGO brick auctions, then went to sleep. Upon waking, he discovered that he was the high bidder on many, and was now the proud owner of two tons of LEGO bricks. (This is about 4400 pounds.) He wrote, "[L]esson 1: if you win almost all bids you are bidding too high."

Mattheij had noticed that bulk, unsorted bricks sell for something like €10/kilogram, whereas sets are roughly €40/kg and rare parts go for up to €100/kg. Much of the value of the bricks is in their sorting. If he could reduce the entropy of these bins of unsorted bricks, he could make a tidy profit. While many people do this work by hand, the problem is enormous—just the kind of challenge for a computer. Mattheij writes:

There are 38000+ shapes and there are 100+ possible shades of color (you can roughly tell how old someone is by asking them what lego colors they remember from their youth).

In the following months, Mattheij built a proof-of-concept sorting system using, of course, LEGO. He broke the problem down into a series of sub-problems (including "feeding LEGO reliably from a hopper is surprisingly hard," one of those facts of nature that will stymie even the best system design). After tinkering with the prototype at length, he expanded the system to a surprisingly complex system of conveyer belts (powered by a home treadmill), various pieces of cabinetry, and "copious quantities of crazy glue."

Here's a video showing the current system running at low speed:

The key part of the system was running the bricks past a camera paired with a computer running a neural net-based image classifier. That allows the computer (when sufficiently trained on brick images) to recognize bricks and thus categorize them by color, shape, or other parameters. Remember that as bricks pass by, they can be in any orientation, can be dirty, can even be stuck to other pieces. So having a flexible software system is key to recognizing—in a fraction of a second—what a given brick is, in order to sort it out. When a match is found, a jet of compressed air pops the piece off the conveyer belt and into a waiting bin.

After much experimentation, Mattheij rewrote the software (several times in fact) to accomplish a variety of basic tasks. At its core, the system takes images from a webcam and feeds them to a neural network to do the classification. Of course, the neural net needs to be "trained" by showing it lots of images, and telling it what those images represent. Mattheij's breakthrough was allowing the machine to effectively train itself, with guidance: Running pieces through allows the system to take its own photos, make a guess, and build on that guess. As long as Mattheij corrects the incorrect guesses, he ends up with a decent (and self-reinforcing) corpus of training data. As the machine continues running, it can rack up more training, allowing it to recognize a broad variety of pieces on the fly.

Here's another video, focusing on how the pieces move on conveyer belts (running at slow speed so puny humans can follow). You can also see the air jets in action:

In an email interview, Mattheij told Mental Floss that the system currently sorts LEGO bricks into more than 50 categories. It can also be run in a color-sorting mode to bin the parts across 12 color groups. (Thus at present you'd likely do a two-pass sort on the bricks: once for shape, then a separate pass for color.) He continues to refine the system, with a focus on making its recognition abilities faster. At some point down the line, he plans to make the software portion open source. You're on your own as far as building conveyer belts, bins, and so forth.

Check out Mattheij's writeup in two parts for more information. It starts with an overview of the story, followed up with a deep dive on the software. He's also tweeting about the project (among other things). And if you look around a bit, you'll find bulk LEGO brick auctions online—it's definitely a thing!

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10 Facts About the Tomb of the Unknown Soldier
May 29, 2017
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Library of Congress

On Veterans Day, 1921, President Warren G. Harding presided over an interment ceremony at Arlington National Cemetery for an unknown soldier who died during World War I. Since then, three more soldiers have been added to the Tomb of the Unknowns (also known as the Tomb of the Unknown Soldier) memorial—and one has been disinterred. Below, a few things you might not know about the historic site and the rituals that surround it.

1. THERE WERE FOUR UNKNOWN SOLDIER CANDIDATES FOR THE WWI CRYPT. 

Wikimedia Commons // Public Domain

To ensure a truly random selection, four unknown soldiers were exhumed from four different WWI American cemeteries in France. U.S. Army Sgt. Edward F. Younger, who was wounded in combat and received the Distinguished Service Medal, was chosen to select a soldier for burial at the Tomb of the Unknowns in Arlington. After the four identical caskets were lined up for his inspection, Younger chose the third casket from the left by placing a spray of white roses on it. The chosen soldier was transported to the U.S. on the USS Olympia, while the other three were reburied at Meuse Argonne American Cemetery in France.

2. SIMILARLY, TWO UNKNOWN SOLDIERS WERE SELECTED AS POTENTIAL REPRESENTATIVES OF WWII.

One had served in the European Theater and the other served in the Pacific Theater. The Navy’s only active-duty Medal of Honor recipient, Hospitalman 1st Class William R. Charette, chose one of the identical caskets to go on to Arlington. The other was given a burial at sea.

3. THERE WERE FOUR POTENTIAL KOREAN WAR REPRESENTATIVES.

WikimediaCommons // Public Domain

The soldiers were disinterred from the National Cemetery of the Pacific in Hawaii. This time, Army Master Sgt. Ned Lyle was the one to choose the casket. Along with the unknown soldier from WWII, the unknown Korean War soldier lay in the Capitol Rotunda from May 28 to May 30, 1958.

4. THE VIETNAM WAR UNKNOWN WAS SELECTED ON MAY 17, 1984.

Medal of Honor recipient U.S. Marine Corps Sgt. Maj. Allan Jay Kellogg, Jr., selected the Vietnam War representative during a ceremony at Pearl Harbor.

5. BUT THE VIETNAM VETERAN WASN'T UNKNOWN FOR LONG.

Wikipedia // Public Domain

Thanks to advances in mitochondrial DNA testing, scientists were eventually able to identify the remains of the Vietnam War soldier. On May 14, 1998, the remains were exhumed and tested, revealing the “unknown” soldier to be Air Force 1st Lt. Michael Joseph Blassie (pictured). Blassie was shot down near An Loc, Vietnam, in 1972. After his identification, Blassie’s family had him moved to Jefferson Barracks National Cemetery in St. Louis. Instead of adding another unknown soldier to the Vietnam War crypt, the crypt cover has been replaced with one bearing the inscription, “Honoring and Keeping Faith with America’s Missing Servicemen, 1958-1975.”

6. THE MARBLE SCULPTORS ARE RESPONSIBLE FOR MANY OTHER U.S. MONUMENTS. 

The Tomb was designed by architect Lorimer Rich and sculptor Thomas Hudson Jones, but the actual carving was done by the Piccirilli Brothers. Even if you don’t know them, you know their work: The brothers carved the 19-foot statue of Abraham Lincoln for the Lincoln Memorial, the lions outside of the New York Public Library, the Maine Monument in Central Park, the DuPont Circle Fountain in D.C., and much more.

7. THE TOMB HAS BEEN GUARDED 24/7 SINCE 1937. 

Tomb Guards come from the 3rd U.S. Infantry Regiment "The Old Guard". Serving the U.S. since 1784, the Old Guard is the oldest active infantry unit in the military. They keep watch over the memorial every minute of every day, including when the cemetery is closed and in inclement weather.

8. BECOMING A TOMB GUARD IS INCREDIBLY DIFFICULT.

Members of the Old Guard must apply for the position. If chosen, the applicant goes through an intense training period, in which they must pass tests on weapons, ceremonial steps, cadence, military bearing, uniform preparation, and orders. Although military members are known for their neat uniforms, it’s said that the Tomb Guards have the highest standards of them all. A knowledge test quizzes applicants on their memorization—including punctuation—of 35 pages on the history of the Tomb. Once they’re selected, Guards “walk the mat” in front of the Tomb for anywhere from 30 minutes to two hours, depending on the time of year and time of day. They work in 24-hour shifts, however, and when they aren’t walking the mat, they’re in the living quarters beneath it. This gives the sentinels time to complete training and prepare their uniforms, which can take up to eight hours.

9. THE HONOR IS ALSO INCREDIBLY RARE.

The Tomb Guard badge is the least awarded badge in the Army, and the second least awarded badge in the overall military. (The first is the astronaut badge.) Tomb Guards are held to the highest standards of behavior, and can have their badge taken away for any action on or off duty that could bring disrespect to the Tomb. And that’s for the entire lifetime of the Tomb Guard, even well after his or her guarding duty is over. For the record, it seems that Tomb Guards are rarely female—only three women have held the post.

10. THE STEPS THE GUARDS PERFORM HAVE SPECIFIC MEANING.

Everything the guards do is a series of 21, which alludes to the 21-gun salute. According to TombGuard.org:

The Sentinel does not execute an about face, rather they stop on the 21st step, then turn and face the Tomb for 21 seconds. They then turn to face back down the mat, change the weapon to the outside shoulder, mentally count off 21 seconds, then step off for another 21 step walk down the mat. They face the Tomb at each end of the 21 step walk for 21 seconds. The Sentinel then repeats this over and over until the Guard Change ceremony begins.

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