kottke.org posts about science
Crackerjack science writer Ed Yong is coming out with his very first book in a month's time. It's called I Contain Multitudes (good title!) and is about "astonishing partnerships between animals and microbes".
Every animal, whether human, squid, or wasp, is home to millions of bacteria and other microbes. Ed Yong, whose humor is as evident as his erudition, prompts us to look at ourselves and our animal companions in a new light-less as individuals and more as the interconnected, interdependent multitudes we assuredly are.
The microbes in our bodies are part of our immune systems and protect us from disease. In the deep oceans, mysterious creatures without mouths or guts depend on microbes for all their energy. Bacteria provide squid with invisibility cloaks, help beetles to bring down forests, and allow worms to cause diseases that afflict millions of people.
I will read anything described as "like a David Attenborough series shot through a really good microscope".
While we're on the subject, NASA announced late last week that they are extending the missions of nine spacecraft sprinkled about the solar system. Included are the New Horizon probe, which will wing off to study an object in the Kuiper Belt after doing so well with Pluto and the rover Opportunity, which was slated for a mission lasting just over 90 days but has now spent more than 12 years exploring the surface of Mars.
The Dawn mission to Ceres is another spacecraft whose duration has been extended, beating long odds. Part of the spacecraft's functionality had not been working for some time, but was recently repaired.
It was a bit unexpected because Dawn is low on fuel. "Less than a year ago, I would have thought it was ridiculous that the spacecraft would even be operating at this point," said Marc D. Rayman, the chief engineer for the Dawn mission.
The Dawn spacecraft was designed to use four spinning wheels to pivot in different directions. But at its previous destination, the asteroid Vesta, two of the four wheels overheated and failed. At Ceres, the wheels stayed off, and the spacecraft used its thrusters instead to pivot.
In December, Dawn reached its lowest orbit, just 240 miles above Ceres. Dr. Rayman said he and his team had expected Dawn to exhaust its remaining propellant by March.
But they spun up the wheels again. That succeeded, cutting the use of the thrusters. "It all worked out beautifully," Dr. Rayman said. That left enough fuel to contemplate doing something more.
After a voyage from Earth lasting almost 5 years, the Juno spacecraft successfully entered Jupiter's orbit late last night.
The engine burn was tense. 35 minutes is a long time for a spacecraft burn; after 20 minutes it had slowed Juno enough to be in orbit, but not the correct one. It had to continue for another 15 minutes to put the spacecraft on the correct orbit. It worked essentially perfectly. The burn time was off by just one second. That will have no real effect on the orbit.
The 35-minute burn slowed Juno down by more than 1200 mph.
How old are different parts of our bodies? Does anything stick around the entire time? The hair on our bodies lasts only a few years. Fingernails are fully replaced every six months. Your skin lasts 2-4 weeks. Even your blood and bones regenerate every so often. There's at least one part of your body with lasts the whole time you're alive, which I found somewhat surprising. See the ship of Theseus paradox.
The ship wherein Theseus and the youth of Athens returned from Crete had thirty oars, and was preserved by the Athenians down even to the time of Demetrius Phalereus, for they took away the old planks as they decayed, putting in new and stronger timber in their places, in so much that this ship became a standing example among the philosophers, for the logical question of things that grow; one side holding that the ship remained the same, and the other contending that it was not the same.
How do we know the lifespans of different cells in the body? Carbon-14 levels from nuclear testing done in the 50s and 60s.
Analysis of growth rings from pine trees in Sweden shows that the proliferation of atomic tests in the 1950s and 1960s led to an explosion in levels of atmospheric carbon 14. Now, Jonas Frisen and colleagues at the Karolinska Institute in Stockholm have taken advantage of this spike in C14 to devise a method to date the birth of human cells. Because this test can be used retrospectively, unlike many of the current methods used to detect cell proliferation, and because it does not require the ingestion of a radioactive or chemical tracer, the method can be readily applied to both in vivo and postmortem samples of human tissues.
Launched from Earth in August 2011, the Juno probe is due to arrive at Jupiter on July 4, 2016. Once there, it will circle Jupiter 37 times, observing its atmosphere and magnetic fields, before plunging into the giant planet so as not to contaminate Europa with microbes.
Juno's principal goal is to understand the origin and evolution of Jupiter. Underneath its dense cloud cover, Jupiter safeguards secrets to the fundamental processes and conditions that governed our solar system during its formation. As our primary example of a giant planet, Jupiter can also provide critical knowledge for understanding the planetary systems being discovered around other stars.
With its suite of science instruments, Juno will investigate the existence of a solid planetary core, map Jupiter's intense magnetic field, measure the amount of water and ammonia in the deep atmosphere, and observe the planet's auroras.
Juno will let us take a giant step forward in our understanding of how giant planets form and the role these titans played in putting together the rest of the solar system.
Science is great. That video? Maybe not so much.
After an unbelievably stressful and busy winter/spring, I am hoping to find some time to read this summer. One of the books on my short list is Sean Carroll's The Big Picture, one of those "everything is connected" things I love. From a post by Carroll on what the book's about:
This book is a culmination of things I've been thinking about for a long time. I've loved physics from a young age, but I've also been interested in all sorts of "big" questions, from philosophy to evolution and neuroscience. And what these separate fields have in common is that they all aim to capture certain aspects of the same underlying universe. Therefore, while they are indisputably separate fields of endeavor -- you don't need to understand particle physics to be a world-class biologist -- they must nevertheless be compatible with each other -- if your theory of biology relies on forces that are not part of the Standard Model, it's probably a non-starter. That's more of a constraint than you might imagine. For example, it implies that there is no such thing as life after death. Your memories and other pieces of mental information are encoded in the arrangement of atoms in your brain, and there's no way for that information to escape your body when you die.
Yeah, that sounds right up my alley.
Not everyone can distinguish between left and right. Besides natural affinity (or lack of it), health, drug use, other chemical changes, and stress can all cause our basic body compass to break down.
Telling left from right necessitates complex brain processes that include spatial perceptions, memory, language, and the integration of sensory information. The task is made increasingly complex when a person must identify laterality on someone else. Yoga teachers and other fitness instructors have it extra rough: While calling out to students to bend their left knee, the instructor has to raise their own right to mirror the class...
However, the field under the most pressure to avoid lateral confusion is medicine. In the dentist's chair, there's money wasted when hygienists x-ray the wrong tooth. It's even worse when a left-right-disoriented dentist pulls one or more teeth from the incorrect side of the mouth. It's even more serious in general surgery: A 2011 report estimates that there are 40 wrong-site surgeries done weekly in the U.S., and many of those involve mixing up a patient's left and right. This is a devastating problem: If a doctor removes the healthy kidney and not the cancerous one, the results can be fatal. Wrong eye? Now we have a fully blind patient.
There's nothing inherent about left, right, up, and down -- or what are sometimes called "egocentric coordinates." Speakers of Guugu Yimithirr in Australia famously use a coordinate system that leans much more heavily on absolute geocentric references at right angles (their equivalent of north, south, east, and west).
This plays a little easier when you're playing off objects with fixed positions, like landmarks, or especially, the sun, than it does in big twisty-turny cities. But you could imagine in a world with ubiquitous handheld maps and compasses that a north/south/east/west orientation might make more sense.
What's more, some of the old tech people used to train themselves to distinguish or remember left and right -- miming handwriting, or wearing a wristwatch on one arm -- aren't as common or dominant as they once were. See also: distinguishing angular position by analogy with the face of an analog clock.
Either we come up with new tricks and new metaphors, or it's conceivable that what's seemed like an intuitive, natural way to think about the relative position of bodies in space could become a whole lot less intuitive for more and more people.
Adam Summers is a biomechanist who worked as a consultant on fish behavior and anatomy for Pixar's Finding Nemo and its sequel, Finding Dory. How do you figure out where and how to stick to the known science (or sneak it in sideways) in a movie about talking fish? It's not an easy question to answer.
This question is very important for the entertainment industry: does it matter whether you're right, when you're telling a story to entertain? Under some circumstances, I don't think it matters. But with an animated movie about real, living systems, when you use the truth -- their complexity and beauty -- as a springboard for the story, you add a level of gravitas that is vitally important to creating a broad and deep appeal. A young audience is much more sophisticated than you think, and a story informed by a lot of facts alerts them to the presence of real concepts. I got an e-mail from an eight-year-old about Finding Nemo, explaining that characters could not emerge from a whale's blowhole if they were in its mouth, because there is no link between the trachea and the oesophagus.
There are over 100 inaccuracies in Finding Nemo, but Summers says only one is a genuine error. (He doesn't name it, but it might be Mr. Ray, who lists names of classes in his song about aquatic species.) Everything else, from the whale's blowhole to ignoring clownfish's ability to switch between male and female (although what if Marlin does become female, but just never spawns again?) is an intentional gloss or omission for storytelling purposes.
Or aesthetic ones. "The claspers -- external, stick-like sexual organs on sharks -- were cut off Bruce the great white shark," says Summers, "not because of family values, but because he's spherical, and when you add a bunch of sticks to spherical sharks, they look really stupid." Noted.
Summers admits there's also just a lot about the species in Pixar's fish movies that nobody really knows.
They did ask me some questions about the biology of whale sharks (Rhincodon typus) that we just don't know the answers to. It's the largest fish in the sea, yet I think there's just one record of a pregnant female, which revealed that they can have more than 300 pups at a time. That's not much to know about the reproductive biology of such an iconic fish.
Tim Doucette is a legally blind astronomer. A pair of surgeries when he was younger to help improve his vision left him with a superpower: because his pupils were permanently dilated, he could see in the dark better than other people. He built an observatory and with the aid of his telescope, he can see details of far-off stars and nebula that no one else can, including UV and infrared light.
Siddhartha Mukherjee, who wrote The Emperor of All Maladies, a biography of cancer and one of my favorite recent reads, is out with a new book called The Gene: An Intimate History.
Siddhartha Mukherjee has a written a biography of the gene as deft, brilliant, and illuminating as his extraordinarily successful biography of cancer. Weaving science, social history, and personal narrative to tell us the story of one of the most important conceptual breakthroughs of modern times, Mukherjee animates the quest to understand human heredity and its surprising influence on our lives, personalities, identities, fates, and choices.
The book comes recommended by Tyler Cowen, who IIRC also recommended Emperor of All Maladies to me.
This book filled in a number of gaps in my knowledge, plus it is engaging to read. Overall it confirmed my impression of major advances in the science, but not matched by many medical products for general use.
This is on the must-read list this summer. Somehow. When I get a second.
Kurzgesagt and CGPGrey collaborated on a pair of videos about the self. The first video considers the human being as a collection of cells. How many of those cells can you take away before you stop being you? And does that question even make sense? The second video notes that if you sever the connection between the two halves of the human brain, they will each seemingly continue to operate as separate entities. But which of those entities is you? Are there two yous?
The B-2 stealth bomber has a length of 69 feet and a wingspan of 172 feet but possesses the radar profile of a large bird. How does the plane evade radar so effectively?
In the 90s, Bruniquel Cave was discovered to have a chamber containing an interesting human-built structure made from broken stalagmites. Carbon dating of a burnt bear bone within the chamber put the age of the activity at 47,600 years ago, smack dab in the Neanderthal era in that area. But recently, after a lull in research about these cave structures, analysis of uranium levels in the broken stalagmites resulted in a much older date for the construction: 176,500 years ago.
Nor is it clear how the Neanderthals made the structures. Verheyden says it couldn't have been one lone artisan, toiling away in the dark. Most likely, there was a team, and a technically skilled one at that. They broke rocks deliberately, and arranged them precisely. They used fire, too. More than 120 fragments have red and black streaks that aren't found elsewhere in the chamber or the cave beyond. They were the result of deliberately applied heat, at intensities strong enough to occasionally crack the rock. "The Neanderthal group responsible for these constructions had a level of social organization that was more complex than previously thought," the team writes.
Jller is a machine that sorts stones from a specific river according to their geologic age.
The machine works with a computer vision system that processes the images of the stones and maps each of its location on the platform throughout the ordering process. The information extracted from each stone are dominant color, color composition, and histograms of structural features such as lines, layers, patterns, grain, and surface texture. This data is used to assign the stones into predefined categories.
See also the robotic pancake sorter. (via colossal)
After The Man freaked out back in the 60s, LSD and other psychedelics were banned and criminalized. But slowly, scientists are experimenting with psychedelics to treat depression, anxiety, and other ailments.
In the 1960s, a psychologist and former Harvard teacher named Timothy Leary coined the phrase 'Turn on. Tune in. Drop out.' The slogan was inspired by advertising jingles, but Leary wasn't pushing a product, he was promoting a drug: LSD.
But today, scientists are studying psychedelics once again, in the latest twist in the long, strange story of LSD.
Even outside of a therapeutic setting, many people extolled the beneficial effects of psychedelics. Former Apple CEO Steve Jobs recalled in his biography by Walter Isaacson:
Taking LSD was a profound experience, one of the most important things in my life. LSD shows you that there's another side to the coin, and you can't remember it when it wears off, but you know it. It reinforced my sense of what was important -- creating great things instead of making money, putting things back into the stream of history and of human consciousness as much as I could.
Check out the NY Times companion piece and the archival footage of LSD experiments on cats, spiders, and goats.
If you're clever, you can take normal sand or dirt and support really heavy things with it. Near the end of this video, a small block of reinforced sand holds up a car wheel with absolutely no difficulty.
And yes, the Practical Engineering YouTube channel is a new favorite. (via digg)
Errol Morris has made a short film about the world's remaining stocks of smallpox virus 1 and the debate between those who want to eliminate the virus forever and those who want to keep it around.
In the story from classical Greece, Pandora was warned: Don't open the box. She opens it anyway. The various pestilences are unleashed on the world but Hope remains at the very bottom of the box. Today there are microbiologists who want to continue to research smallpox. If they are given a free hand, what might they unleash?
There are those who insist that these residual stocks of smallpox should not be destroyed because some ruthless super-criminal or rogue government might be working on a new smallpox, even more virulent than existing strains of the virus. We may need existing stocks to produce new vaccines to counteract the new viruses. New viruses, new vaccines. New vaccines, new viruses. An escalating arms race with germs.
Keep this video in mind when you read about the latest advances with CRISPR.
A new video from Kurzgesagt explores the limits of human exploration in the Universe. How far can we venture? Are there limits? Turns out the answer is very much "yes"...with the important caveat "using our current understanding of physics", which may someday provide a loophole (or wormhole, if you will). Chances are, humans will only be able to explore 0.00000000001% of the observable Universe.
This video is particularly interesting and packed with information, even by Kurzgesagt's standards. The explanation of the Big Bang, inflation, dark matter, and expansion is concise and informative...the idea that the Universe is slowly erasing its own memory is fascinating.
On Last Week Tonight last night, John Oliver took the media's often shoddy coverage of science to task. Like cherry picking the results of single studies that "prove" that chocolate prevents cancer and that sort of thing.
As a somewhat reluctant member of "the media", I've been guilty of this sort of behavior to varying degrees in the past. In the last few years, I've been working to improve on this count -- by reading studies, declining to post stuff that doesn't make the grade, reading what other trusted media sources are saying, using softer language like "could" or "may" instead of "does", distinguishing between correlation and causation -- but I still make mistakes.
At a certain point though, you have to rely on the scientific literacy of your readers. I can't explain the scientific process to everyone every single time. At some point, I need to assume we're all taking the results of studies with a similarly sized grain of salt.
In the end, I love science and I want you to love it too. That's why I often write about it, about the history of how we came to know what we know, about the limits of our knowledge, and, especially, about efforts to push beyond the boundaries of the known. There's always the temptation to gussy science up, to fit the facts to my world view. But deep down, I know that's unnecessary -- science is awesome all by itself! -- and harms the goal of increasing scientific literacy and interest. I'm gonna trying reminding myself of that more in the future.
15-year-old Canadian William Gadoury has translated his interest in the Mayan civilization into two remarkable discoveries. Gadoury noticed that the locations of the biggest Mayan cities matched the locations of the stars in Mayan constellations. Furthermore, the star charts pointed to the existence of a previously unknown city, the ruins of which have since been uncovered by satellite photography.
"I did not understand why the Maya built their cities away from rivers, on marginal lands and in the mountains," said Gadoury. "They had to have another reason, and as they worshiped the stars, the idea came to me to verify my hypothesis. I was really surprised and excited when I realized that the most brilliant stars of the constellations matched the largest Maya cities."
Someone start a Kickstarter campaign so that he can visit those ruins! (via @delfuego)
Update: Due to a mislabeled file on Wikipedia, I used a photo of an Aztec compass instead of a Mayan image. I have replaced with an image of the Mayan zodiac.
Also, per my post about media coverage of science yesterday, I'll point out quickly that there's much to be skeptical about re: this story (see this post from a Mesoamerican archaeologist). More likely than not, there's a Mayan scholar mailing list going bananas right now...I'll let you know if I hear anything specific.
In the meantime, this story in the Independent contains some satellite photos of the location in question. (via @gunnihinn)
Update: Vice: That 15-Year-Old Kid Probably Didn't Discover a Hidden Mayan City.
The rectangular feature seen on satellite is likely an old corn field (it's not the right shape to be a pyramid). There are indeed ancient Maya sites all over the place, and satellite imagery and LiDAR are being used to discover them, but this doesn't seem to be one of those cases...
On the bright side, the "if it sounds too good to be true, it probably is" study has been successfully replicated again. Science rolls on...
Jimmy Kimmel had some scientists on his show recently to tell the American public that anthropogenic climate change is real, that's it's not a prank, and that the scientific community is "not fucking with you" about this. Trigger warning: the first minute of this video features Sarah Palin speaking.
The latest video from Kurzgesagt is on space elevators. How would you build one? Why not just keep launching rockets into space instead? Would be easier to build one on the Moon first?
In the past two weeks, the results of three surveys and studies about the Earth's climate have been released: a paper on a possible dramatic climate shift, a survey of coral bleaching at the Great Barrier Reef, and a study on the West Antarctic ice sheet. All three investigations tell the story of climate change happening quicker than was previously anticipated.
From the paper published last week by former NASA climate scientist James Hansen and a number of colleagues:
Virtually all climate scientists agree with Dr. Hansen and his co-authors that society is not moving fast enough to reduce emissions of greenhouse gases, posing grave risks. The basic claim of the paper is that by burning fossil fuels at a prodigious pace and pouring heat-trapping gases into the atmosphere, humanity is about to provoke an abrupt climate shift.
In Australia, more than 40% of the Great Barrier Reef has been damaged by coral bleaching.
Scientists who have dedicated their careers to studying the reef and its ecosystem say the current bleaching is unprecedented, and perhaps unrecoverable. The emotion in their responses so far have been palpable.
"I witnessed a sight underwater that no marine biologist, and no person with a love and appreciation for the natural world for that matter, wants to see," said Australian coral scientist Jodie Rummer in a statement, after spending more than a month at a monitoring station in the Great Barrier Reef.
Though corals comprise only about 0.2 percent of the global oceans, they support perhaps a quarter of all marine species.
And just yesterday, a study on the West Antarctic ice sheet was released that says the ice sheet could melt much faster than previously thought, raising global sea levels by 3 feet in less than 90 years. Even the normally staid NY Times invoked the Sword of Damocles in the lede.
The great ice sheet, larger than Mexico, is thought to be potentially vulnerable to disintegration from a relatively small amount of global warming, and capable of raising the sea level by 12 feet or more should it break up. But researchers long assumed the worst effects would take hundreds -- if not thousands -- of years to occur.
Now, new research suggests the disaster scenario could play out much sooner.
Continued high emissions of heat-trapping gases could launch a disintegration of the ice sheet within decades, according to a study published Wednesday, heaving enough water into the ocean to raise the sea level as much as three feet by the end of this century.
Miami might not make it to the end of the century.
Oh and BTW, the maximum extent of sea ice in the Arctic was a record low in 2016, February was a total Messi-esque outlier in terms of how unusually hot it was, March, while not as warm, will still be the hottest March ever, and just look at the 2016 trend in the first chart here.
You can think of the Earth as a massive machine, with many interconnected, resilient, and redundant systems. For a long time, humans thought it was too big for our actions to affect this machine in a meaningful way. But the Industrial Revolution's release of hundreds of millions of years of stored greenhouse gases in less than 300 years put a strain on that entire machine. We didn't notice that strain for a long time, but we're starting to now in the form of higher temperatures, weird weather, bleaching coral reefs, rapidly melting ice sheets in Greenland & Antarctica, and dozens of other ways. I hope there's still time to do something meaningful about it before the slower moving parts of the machine fail permanently.
In 1989, a Rockwell engineer named Ron Jones published his Integrated Space Plan, a detailed outline of the next 100 years of human space travel, from continuing shuttle missions in the 1990s to the large scale habitation of Mars. The plan includes all sorts of futuristic and day-dreamy phrases like:
Create new moons for Mars if required
Humanity begins the transition from a terrestrial to a solar species
Humanity commands unlimited resources from the Moon and asteroids
Space drives global economy
Independent spacefaring human communities
Wired has a good look at how the plan came to be.
The graphic is divided into nine columns that show, in chronological order, the path toward human exploration of deep space. The center row of boxes, the "critical path," outlines the major milestones Jones decided were attainable within the next century of space travel; the boxes to the left and right of the critical path are support elements that must be realized before anything on the critical path can happen. The Integrated Space Plan can be read top to bottom and left to right. The big circles intersecting the boxes are the the plan's overarching long-range goals, which include things like Humanity begins the transition from a terrestrial to a solar species and Human expansion into the cosmos. In many ways, it's a graphical to-do list.
The keen observer will note that we are waaaaay behind in the plan. A lunar outpost was supposed to be up and running before 2008 and a self-supporting lunar base is due to happen in the next year or two. Can Musk and Bezos get us back on track? (via @ftrain)
Stewart Brand wrote a summary of a seminar given by Jane Langdale about how the efficiency of photosynthesis might be improved for some of the world's plants, particularly rice.
Most plants use what's called C3 photosynthesis to produce sugars and starch, but the process is not very efficient. Some plants, like corn and sugarcane, have evolved the capability to produce sugars and starch using the much more efficient C4 photosynthesis process. So if you could modify rice to use C4 instead of C3, yields would increase dramatically.
Rice is a C3 plant -- which happens to be the staple food for half the world. If it can be converted to C4 photosynthesis, its yield would increase by 50% while using half the water. It would also be drought-resistant and need far less fertilizer.
You can read more about the efforts in developing C4 photosynthesis in Technology Review.
Randall Munroe's best-selling Thing Explainer, in which he explains scientific concepts using only the 1000 most common words, will be incorporated into the upcoming editions of some of Houghton Mifflin Harcourt's high school science textbooks.
Mr. Munroe, 31, said the project appealed to him. He recalled as a child a foldout diagram showing different animals at the starting line of a race and then sprinting/flying/crawling to show the different speeds of different species. "For some reason, I fixated on that illustration," he said. "It stuck with me my entire life."
Mr. Munroe said he hoped his drawings would break up the monotony and pace of a typical textbook. "I'm hoping it will be, 'Oh, here's a kind of fun and unexpected component,'" he said.
I think Bill Gates would approve.
A new paper by climate scientists, including ex-NASA scientist James Hansen, warns that our climate could dramatically change within decades, not centuries.
Virtually all climate scientists agree with Dr. Hansen and his co-authors that society is not moving fast enough to reduce emissions of greenhouse gases, posing grave risks. The basic claim of the paper is that by burning fossil fuels at a prodigious pace and pouring heat-trapping gases into the atmosphere, humanity is about to provoke an abrupt climate shift.
Non-linear systems, man. Gradually, then all at once.
Update: Slate's Eric Holthaus has more on the paper and its potential implications.
In addition to the risk of "several meters" of sea level rise this century, which Hansen calls the most important finding, the final version of Hansen's paper gives new emphasis to the possibility that the ocean's heat circulation system may be in the process of shutting down. The circulation shutdown would precede the rapid increase in global sea levels. If the shutdown happens, simultaneous cooling of the waters near Greenland and Antarctica and warming in the tropics and midlatitudes could spawn frequent strong storms on the order of Hurricane Sandy or worse.
If that sounds a lot like the plot of The Day After Tomorrow to you, you're not alone.
Hansen also released a 15-minute video about the paper:
Mathematicians have calculated pi out to more than 13 trillion decimal places, a calculation that took 208 days. NASA's Marc Rayman explains that in order to send out probes and slingshot them accurately throughout the solar system, NASA needs to use only 15 decimal places, or 3.141592653589793. How precise are calculations with that number? This precise:
The most distant spacecraft from Earth is Voyager 1. It is about 12.5 billion miles away. Let's say we have a circle with a radius of exactly that size (or 25 billion miles in diameter) and we want to calculate the circumference, which is pi times the radius times 2. Using pi rounded to the 15th decimal, as I gave above, that comes out to a little more than 78 billion miles. We don't need to be concerned here with exactly what the value is (you can multiply it out if you like) but rather what the error in the value is by not using more digits of pi. In other words, by cutting pi off at the 15th decimal point, we would calculate a circumference for that circle that is very slightly off. It turns out that our calculated circumference of the 25 billion mile diameter circle would be wrong by 1.5 inches. Think about that. We have a circle more than 78 billion miles around, and our calculation of that distance would be off by perhaps less than the length of your little finger.
When was humanity's calculation of pi accurate enough for NASA? In 1424, Persian astronomer and mathematician Jamshid al-Kashi calculated pi to 17 digits.
There are some things that humans don't need to survive anymore still hanging around on our bodies, including unnecessary arm muscles and vestigial tail bones.
The latest video from Kurzgesagt is an explainer on antibiotics and superbugs (drug resistant bacteria).
What would you say if we told you that humanity is currently making a collaborative effort to engineer the perfect superbug, a bug that could kill hundreds of millions of people?
The common button or white mushroom, the crimini or brown mushroom, and the portobello mushroom are all the same species of mushroom.
Agaricus bisporus has increased in popularity in North America with the introduction of two brown strains, Portabella (sometimes also spelled portobello, portabello, or portobella) and Crimini. The three mushrooms you see to the right are all actually the same species. Portabella is a marketing name the mushroom industry came up with for more flavorful brown strains of Agaricus bisporus that are allowed to open to expose the mature gills with brown spores; crimini is actually the same brown strain that is not allowed to open before it is harvested.
See also the magical Brassica oleracea plant (cabbage, kale, broccoli, brussels sprouts, kohlrabi, collard greens, and cauliflower are all the same species of plant). (via @dunstan)
First contact with an alien civilization will be a momentous event in the history of Earth. Unless the other civilization is kind of a dick. Tim Urban didn't quite cover this scenario in his post about the Fermi Paradox.
With the homemade telescope in his backyard observatory, amateur astronomer Gary Hug has discovered over 300 asteroids.
I've pretty much stopped watching science and engineering TV shows because their information density is often so low. Mythbusters is no exception, but this clever YouTube channel helpfully edits the 44-minute episodes down to a svelte and info-packed 2-5 minutes. (via digg)
With amazing super slow-motion footage of a match head starting to burn as a backdrop, this video explains the chemical reactions involved in lighting a match.
When the match is struck, a small amount of the red phosphorus on the striking surface is converted into white phosphorus, which then ignites. The heat from this ignites the potassium chlorate, and the match head bursts into flame. During manufacture, the match stick itself is soaked in ammonium phosphate, which prevents 'afterglow' once the flame has gone out, and paraffin, which ensures that it burns easily.
In an all-white room, mosquitoes are mated and the resulting larvae divided by sex. Workers whisk at stray mosquitoes with electrified tennis rackets -- the kind you see in novelty stores, but which have sold out in mosquito-obsessed Brazil.
MIT Tech Review takes you inside the mosquito factory that could stop Zika and other diseases. (Add "working in a mosquito factory" to the list of jobs I'm glad I don't have...)
From PHD Comics, and explanation of what gravitational waves are and why their discovery is so important to the future of science. (via df)
Update: Brian Greene's explanation of gravitational waves to Stephen Colbert is the best one yet:
Greene is great at explaining physics in terms almost anyone can understand. Even though it's more than 15 years old now, his book, The Elegant Universe, still contains the best explanation of modern physics (quantum mechanics + relativity) I've ever read.
In How We Got to Now, the TV series based on the book of the same name, Steven Johnson explains how the wine press was used to print books, which resulted in a surge in demand for reading glasses, which had yet more unintended effects.
Johnson calls this cascade of inadvertent invention the Hummingbird Effect.
This is how change happens in the natural world: sometime during the Cretaceous age, flowers began to evolve colors and scents that signaled the presence of pollen to insects, who simultaneously evolved complex equipment to extract the pollen and, inadvertently, fertilize other flowers with pollen.
Over time, the flowers supplemented the pollen with even more energy-rich nectar to lure the insects into the rituals of pollination. Bees and other insects evolved the sensory tools to see and be drawn to flowers, just as the flowers evolved the properties that attract bees. The symbiosis between flowering plants and insects that led to the production of nectar ultimately created an opportunity for much larger organisms -- the hummingbirds -- to extract nectar from plants, though to do that they evolved a extremely unusual form of flight mechanics that enable them to hover alongside the flower in a way that few birds can even come close to doing. In other words, they had to learn an entirely new way to fly.
In an interview with Popular Mechanics, Johnson shared another example:
At the start of the 20th century, in Brooklyn, a printer was doing full-color magazines. In the summer the ink didn't set up properly. The printer hired a young engineer, Willis Carrier, to devise a way to bring down the temperature and humidity in the room. He built this contraption that made the printing possible. Then the workers were like, "I'm gonna have my lunch in the room with the contraption, it's cool in there." Carrier says, "Hmm, that's interesting." He sets up the Carrier Corporation, which air-conditions movie theaters, paving the way for the summer blockbuster. Before air conditioning, a crowded theater was the last place you wanted to go. After a/c, summer movies become part of the cultural landscape.
After a potential detection of gravitational waves back in 2014 turned out to be galactic dust, scientists working on the LIGO experiment have announced they have finally detected evidence of gravitational waves. Nicola Twilley has the scoop for the New Yorker on how scientists detected the waves.
A hundred years ago, Albert Einstein, one of the more advanced members of the species, predicted the waves' existence, inspiring decades of speculation and fruitless searching. Twenty-two years ago, construction began on an enormous detector, the Laser Interferometer Gravitational-Wave Observatory (LIGO). Then, on September 14, 2015, at just before eleven in the morning, Central European Time, the waves reached Earth. Marco Drago, a thirty-two-year-old Italian postdoctoral student and a member of the LIGO Scientific Collaboration, was the first person to notice them. He was sitting in front of his computer at the Albert Einstein Institute, in Hannover, Germany, viewing the LIGO data remotely. The waves appeared on his screen as a compressed squiggle, but the most exquisite ears in the universe, attuned to vibrations of less than a trillionth of an inch, would have heard what astronomers call a chirp -- a faint whooping from low to high. This morning, in a press conference in Washington, D.C., the LIGO team announced that the signal constitutes the first direct observation of gravitational waves.
The NY Times headline above is from when the concept of gravitational lensing suggested by Einstein's theory of relatively was confirmed in 1919. I thought it was appropriate in this case. Wish they still ran headlines like that.
Update: The LIGO team has detected gravitational waves a second time.
Today, the LIGO team announced its second detection of gravitational waves-the flexing of space and time caused by the black hole collision. The waves first hit the observatory in Livingston, Louisiana, and then 1.1 milliseconds later passed through the one in Hanford, Washington.
By now, those waves are 2.8 trillion or so miles away, momentarily reshaping every bit of space they pass through.
For her new book, Ariel Waldman asked dozens of astronauts about their experiences in space.
With playful artwork accompanying each, here are the real stories behind backwards dreams, "moon face," the tricks of sleeping in zero gravity and aiming your sneeze during a spacewalk, the importance of packing hot sauce, and dozens of other cosmic quirks and amazements that come with travel in and beyond low Earth orbit.
Waldman is the co-creator of the very cool spaceprob.es.
Update: This book is now out, shipping, released...launched, if you will.
"I'm looking at a picture of two mice. The one on the right looks healthy. The one on the left has graying fur, a hunched back, and an eye that's been whitened by cataracts."
What's the difference? Well, scientists at the Mayo clinic used a process to remove senescent (or retired) cells from one of them. And that process leads to mice who age better and live longer. As one researcher not connected to the study explains:
The usual caveats apply -- it's got to be reproduced by other people -- but if it's correct, without wanting to be too hyperbolic, it's one of the more important aging discoveries ever.
As part of a celebration of the legacy of Richard Feynman at Caltech this week, Bill Gates contributed a video about what he learned from Feynman.
In that video, I especially love the way Feynman explains how fire works. He takes such obvious delight in knowledge -- you can see his face light up. And he makes it so clear that anyone can understand it.
I love that video as well...just watched it again and it's so so good.
So, this is a time travel movie with Keanu Reeves (narrator) and Alex Winter (director), but it's not Bill & Ted's Excellent Adventure, Part 3? No, of course not. It's actually a video about quantum chess featuring Paul Rudd, Stephen Hawking, and music from The Matrix. Like, WHAT?! If The Chickening hadn't dropped earlier, this would be the oddest thing you'll watch this week. (And it's not quite clear, but the video appears to be an advertisement for a quantum chess game that's launching on Kickstarter next week. Nothing about this makes any sense...) (via @gavinpurcell)
Today is the 30th anniversary of the final launch and subsequent catastrophic loss of the Space Shuttle Challenger. Popular Mechanics has an oral history of the launch and aftermath.
Capano: We got the kids quiet, and then I remember that the line that came across the TV was "The vehicle has exploded." One of the girls in my classroom said, "Ms. Olson [Capano's maiden name], what do they mean by 'the vehicle'?" And I looked at her and I said, "I think they mean the shuttle." And she got very upset with me. She said, "No! No! No! They don't mean the shuttle! They don't mean the shuttle!"
Raymond: The principal came over the PA system and said something like, "We respectfully request that the media leave the building now. Now." Some of the press left, but some of them took off into the school. They started running into the halls to get pictures, to get sound-people were crying, people were running. It was chaos. Some students started chasing after journalists to physically get them out of the school.
I have certainly read about Feynman's O-ring demonstration during the investigation of the disaster, but I hadn't heard this bit:
Kutyna: On STS-51C, which flew a year before, it was 53 degrees [at launch, then the coldest temperature recorded during a shuttle launch] and they completely burned through the first O-ring and charred the second one. One day [early in the investigation] Sally Ride and I were walking together. She was on my right side and was looking straight ahead. She opened up her notebook and with her left hand, still looking straight ahead, gave me a piece of paper. Didn't say a single word. I look at the piece of paper. It's a NASA document. It's got two columns on it. The first column is temperature, the second column is resiliency of O-rings as a function of temperature. It shows that they get stiff when it gets cold. Sally and I were really good buddies. She figured she could trust me to give me that piece of paper and not implicate her or the people at NASA who gave it to her, because they could all get fired.
I wondered how I could introduce this information Sally had given me. So I had Feynman at my house for dinner. I have a 1973 Opel GT, a really cute car. We went out to the garage, and I'm bragging about the car, but he could care less about cars. I had taken the carburetor out. And Feynman said, "What's this?" And I said, "Oh, just a carburetor. I'm cleaning it." Then I said, "Professor, these carburetors have O-rings in them. And when it gets cold, they leak. Do you suppose that has anything to do with our situation?" He did not say a word. We finished the night, and the next Tuesday, at the first public meeting, is when he did his O-ring demonstration.
We were sitting in three rows, and there was a section of the shuttle joint, about an inch across, that showed the tang and clevis [the two parts of the joint meant to be sealed by the O-ring]. We passed this section around from person to person. It hit our row and I gave it to Feynman, expecting him to pass it on. But he put it down. He pulled out pliers and a screwdriver and pulled out the section of O-ring from this joint. He put a C-clamp on it and put it in his glass of ice water. So now I know what he's going to do. It sat there for a while, and now the discussion had moved on from technical stuff into financial things. I saw Feynman's arm going out to press the button on his microphone. I grabbed his arm and said, "Not now." Pretty soon his arm started going out again, and I said, "Not now!" We got to a point where it was starting to get technical again, and I said, "Now." He pushed the button and started the demonstration. He took the C-clamp off and showed the thing does not bounce back when it's cold. And he said the now-famous words, "I believe that has some significance for our problem." That night it was all over television and the next morning in the Washington Post and New York Times. The experiment was fantastic-the American public had short attention spans and they didn't understand technology, but they could understand a simple thing like rubber getting hard.
I never talked with Sally about it later. We both knew what had happened and why it had happened, but we never discussed it. I kept it a secret that she had given me that piece of paper until she died [in 2012].
Whoa, dang. Also not well known is that the astronauts survived the initial explosion and were possibly alive and conscious when they hit the water two and a half minutes later.
Over the December holiday, I read 10:04 by Ben Lerner (quickly, recommended). The novel includes a section on the Challenger disaster and how very few people saw it live:
The thing is, almost nobody saw it live: 1986 was early in the history of cable news, and although CNN carried the launch live, not that many of us just happened to be watching CNN in the middle of a workday, a school day. All other major broadcast stations had cut away before the disaster. They all came back quickly with taped replays, of course. Because of the Teacher in Space Project, NASA had arranged a satellite broadcast of the mission into television sets in many schools -- and that's how I remember seeing it, as does my older brother. I remember tears in Mrs. Greiner's eyes and the students' initial incomprehension, some awkward laughter. But neither of us did see it: Randolph Elementary School in Topeka wasn't part of that broadcast. So unless you were watching CNN or were in one of the special classrooms, you didn't witness it in the present tense.
Oh, the malleability of memory. I remember seeing it live too, at school. My 7th grade English teacher permanently had a TV in her room and because of the schoolteacher angle of the mission, she had arranged for us to watch the launch, right at the end of class. I remember going to my next class and, as I was the first student to arrive, telling the teacher about the accident. She looked at me in disbelief and then with horror as she realized I was not the sort of kid who made terrible stuff like that up. I don't remember the rest of the day and now I'm doubting if it happened that way at all. Only our classroom and a couple others watched it live -- there wasn't a specially arranged whole-school event -- and I doubt my small school had a satellite dish to receive the special broadcast anyway. Nor would we have had cable to get CNN...I'm not even sure cable TV was available in our rural WI town at that point. So...?
But, I do remember the jokes. The really super offensive jokes. The jokes actually happened. Again, from 10:04:
I want to mention another way information circulated through the country in 1986 around the Challenger disaster, and I think those of you who are more or less my age will know what I'm talking about: jokes. My brother, who is three and a half years older than I, would tell me one after another as we walked to and from Randolph Elementary that winter: Did you know that Christa McAuliffe was blue-eyed? One blew left and one blew right; What were Christa McAuliffe's last words to her husband? You feed the kids -- I'll feed the fish; What does NASA stand for? Need Another Seven Astronauts; How do they know what shampoo Christa McAuliffe used? They found her head and shoulders. And so on: the jokes seemed to come out of nowhere, or to come from everywhere at once; like cicadas emerging from underground, they were ubiquitous for a couple of months, then disappeared. Folklorists who study what they call 'joke cycles' track how -- particularly in times of collective anxiety -- certain humorous templates get recycled, often among children.
At the time, I remember these jokes being hilarious1 but also a little horrifying. Lerner continues:
The anonymous jokes we were told and retold were our way of dealing with the remainder of the trauma that the elegy cycle initiated by Reagan-Noonan-Magee-Hicks-Dunn-C.A.F.B. (and who knows who else) couldn't fully integrate into our lives.
Reminds me of how children in Nazi ghettos and concentration camps dealt with their situation by playing inappropriate games.
Even in the extermination camps, the children who were still healthy enough to move around played. In one camp they played a game called "tickling the corpse." At Auschwitz-Birkenau they dared one another to touch the electric fence. They played "gas chamber," a game in which they threw rocks into a pit and screamed the sounds of people dying.
Neoantigen vaccines use the DNA from a cancer patient's own tumor to, hopefully, eradicate the cancer.
For some 50 years, cancer biologists have tried to incite the immune system to attack cancer by targeting molecules that commonly stud the surfaces of malignant cells. These "antigens" act as homing beacons that immune cells find and lock onto (much as antigens on viruses attract the immune system, the basis for preventive vaccines such as that for measles).
Trouble is, normal cells sometimes sport the same antigens as tumors, and the immune system is programmed not to attack antigens found on healthy cells. As a result, revving up the immune system to target common tumor antigens hasn't worked, leading to a number of failed experimental cancer vaccines.
That led biologists to a different approach: siccing the immune system on antigens found only on cancer cells -- and only on the cancer cells of a single patient. "It's highly unlikely that any two patients have the same neoantigens," said Dr. Catherine Wu of Boston's Dana-Farber Cancer Institute. "That's why we have an opportunity to make cancer vaccines truly personalized, loaded with patient-specific neoantigens."
From the Cornell Lab of Ornithology, an animated map of the yearly migratory patterns of 118 bird species in the Western Hemisphere.
La Sorte says a key finding of the study is that bird species that head out over the Atlantic Ocean during fall migration to spend winter in the Caribbean and South America follow a clockwise loop and take a path farther inland on their return journey in the spring. Species that follow this broad pattern include Bobolinks, Yellow and Black-billed cuckoos, Connecticut and Cape May warblers, Bicknell's Thrush, and shorebirds, such as the American Golden Plover.
"These looped pathways help the birds take advantage of conditions in the atmosphere," explains La Sorte. "Weaker headwinds and a push from the northeast trade winds as they move farther south make the fall journey a bit easier. The birds take this shorter, more direct route despite the dangers of flying over open-ocean."
The map was created with data from eBird, a database of crowdsourced bird sightings. They also created a follow-up map which labels each of the species. Look at how far Baird's Sandpiper (#5) flies...all the way from central Argentina to Northern Canada and back. (thx, kevin)
The London Underground recently conducted an experiment on one of the escalators leading out of the busy Holborn station. Instead of letting people walk up the left side of the escalator, they asked them to stand on both sides.
The theory, if counterintuitive, is also pretty compelling. Think about it. It's all very well keeping one side of the escalator clear for people in a rush, but in stations with long, steep walkways, only a small proportion are likely to be willing to climb. In lots of places, with short escalators or minimal congestion, this doesn't much matter. But a 2002 study of escalator capacity on the Underground found that on machines such as those at Holborn, with a vertical height of 24 metres, only 40% would even contemplate it. By encouraging their preference, TfL effectively halves the capacity of the escalator in question, and creates significantly more crowding below, slowing everyone down. When you allow for the typical demands for a halo of personal space that persist in even the most disinhibited of commuters -- a phenomenon described by crowd control guru Dr John J Fruin as "the human ellipse", which means that they are largely unwilling to stand with someone directly adjacent to them or on the first step in front or behind -- the theoretical capacity of the escalator halves again. Surely it was worth trying to haul back a bit of that wasted space.
Leaving aside "the human ellipse" for now,1 how did the theory work in the real life trial? The stand-only escalator moved more than 25% more people than usual:
But the preliminary evidence is clear: however much some people were annoyed, Lau's hunch was right. It worked. Through their own observations and the data they gathered, Harrison and her team found strong evidence to back their case. An escalator that carried 12,745 customers between 8.30 and 9.30am in a normal week, for example, carried 16,220 when it was designated standing only. That didn't match Stoneman's theoretical numbers: it exceeded them.
But not everyone liked being asked to stand for the common good:
"This is a charter for the lame and lazy!" said one. "I know how to use a bloody escalator!" said another. The pilot was "terrible", "loopy," "crap", "ridiculous", and a "very bad idea"; in a one-hour session, 18 people called it "stupid". A customer who was asked to stand still replied by giving the member of staff in question the finger. One man, determined to stride to the top come what may, pushed a child to one side. "Can't you let us walk if we want to?" asked another. "This isn't Russia!"
There's a lesson in income inequality here somewhere...1
This is America in a nutshell. Instead of banning kids from playing football, as the world's leading expert on the football-related head injuries urges, a school district is having their football players drink a brand of chocolate milk that has been shown in a preliminary study to "improve their cognitive and motor function over the course of a season, even after experiencing concussions".
Experimental groups drank Fifth Quarter Fresh after each practice and game, sometimes six days a week, while control groups did not consume the chocolate milk. Analysis was performed on two separate groups: athletes who experienced concussions during the season and those who did not. Both non-concussed and concussed groups showed positive effects from the chocolate milk.
Non-concussed athletes who drank Maryland-produced Fifth Quarter Fresh showed better cognitive and motor scores over nine test measures after the season as compared to the control group.
Concussed athletes drinking the milk improved cognitive and motor scores in four measures after the season as compared to those who did not.
Vice Sports has a quick look at what's wrong with this study.
See also these new helmets designed to "prevent" concussions. The problem is not poorly designed helmets or lack of magic chocolate milk. Those things only make matters worse by implicitly condoning poor behavior, e.g. if helmets prevent concussions, it'll gradually result in harder hitting, which will result in more injuries.
With hindsight, it seems bloody obvious the Sun and not the Earth is the center of the solar system. Occam's razor and all that. (via @somniumprojec)
The Cassini spacecraft took a photo of two moons of Saturn, Tethys and Enceladus, beautifully aligned with each other. The cosmic ballet goes on. (via slate)
You know the vodka that comes in the Crystal Skull head?1 A forensic scientist used facial reconstruction techniques to give the skull a face.
IUPAC, the governing body for the official periodic table of elements, has announced the addition of four new elements to the table: ununtrium, ununpentium, ununseptium, and ununoctium. Those are working names...the teams that discovered each element has been invited to name them.
The proposed names and symbols will be checked by the Inorganic Chemistry Division of IUPAC for consistency, translatability into other languages, possible prior historic use for other cases, etc. New elements can be named after a mythological concept, a mineral, a place or country, a property or a scientist.
Ununoctium is so unstable that its half-life is 0.89 milliseconds and only three or four atoms of the substance have been produced in the past 10 years.
From It's OK To Be Smart, a 12-part series explaining evolution.
If you're interested in strange stories involving brain tumors, fecal bacterium, and Institutional Review Boards, Emily Eakin's "Bacteria on the Brain" for the New Yorker should be right up your alley.
Dr. Paul Muizelaar, then chair of the neurosurgery department at U.C. Davis, undertook a daring approach to treating brain tumors. It might work, but would it help?
The previous month, he had operated on Patrick Egan, a fifty-six-year-old real-estate broker, who also suffered from glioblastoma. Egan was a friend of Muizelaar's, and, like Terri Bradley, he had exhausted the standard therapies for the disease. The tumor had spread to his brain stem and was shortly expected to kill him. Muizelaar cut out as much of the tumor as possible. But before he replaced the "bone flap" -- the section of skull that is removed to allow access to the brain -- he soaked it for an hour in a solution teeming with Enterobacter aerogenes, a common fecal bacterium. Then he reattached it to Egan's skull, using tiny metal plates and screws. Muizelaar hoped that inside Egan's brain an infection was brewing.
Kurzgesagt makes some of the most entertaining science explainers around. Check out their most recent video on black holes.
The winner of the 2015 Small World in Motion competition is Wim van Egmond's video of a single-celled organism consuming a smaller single-celled organism. The winners of the photomicrography contest are worth a look as well.
Over the years, there's been a growing consensus that suggests being happy is correlated with living a long life. Well, you can wipe that smile off your face because a massive study published in The Lancent makes it clear that no such correlation exists. So what about all those studies suggesting that stress and joylessness hastened death's arrival? According the new study's co-author:
In our view, the previous studies haven't been well done. All that's going on is ill health actually was causing unhappiness and stress.
In other words, your unhappiness is going to last longer than you thought.
When you see photos of Jupiter, they're almost always the of same view: the north pole at the top, the gaseous bands perfectly horizontal, and the Red Spot somewhere in the mix. But @robdubbin reminds us that there are other ways of looking at Jupiter. Here's a view of the planet's southern hemisphere:
And the northern hemisphere:
If you take photos of the whole of Jupiter's surface and stretch it out flat, you get something like this:
That last one in particular is worth checking out at full resolution. (via @tcarmody)
If you take two circular magnets and slap them on the ends of a AA battery, the resulting axel will drive on a road of aluminum foil. This is called a homopolar motor and it's one of the simplest machines you can build. How does it work? Well, it's been awhile since my last electromagnetism class, but the homopolar motor works because the combination of the flow of the electric current (from the battery) and the flow of the magnetic current produces a torque via the Lorenz force. This short video explanation should give you a good idea of the principles involved. (via digg)
A European Space Agency probe will be launched into space early next month to help test the last major prediction of Einstein's theory of general relativity: the existence of gravitational waves.
Gravitational waves are thought to be hurled across space when stars start throwing their weight around, for example, when they collapse into black holes or when pairs of super-dense neutron stars start to spin closer and closer to each other. These processes put massive strains on the fabric of space-time, pushing and stretching it so that ripples of gravitational energy radiate across the universe. These are gravitational waves.
The Lisa Pathfinder probe won't measure gravitational waves directly, but will test equipment that will be used for the final detector.
LISA Pathfinder will pave the way for future missions by testing in flight the very concept of gravitational wave detection: it will put two test masses in a near-perfect gravitational free-fall and control and measure their motion with unprecedented accuracy. LISA Pathfinder will use the latest technology to minimise the extra forces on the test masses, and to take measurements. The inertial sensors, the laser metrology system, the drag-free control system and an ultra-precise micro-propulsion system make this a highly unusual mission.
Why isn't it super-fast to fly west in an airplane, given that the Earth is spinning at 700-1000 miles per hour relative to its center? This seems like a sorta-variation on the old airplane on a treadmill question, doesn't it?
The Cassini probe, launched from Earth in 1997 (six months before I started publishing kottke.org), has been taking photos of Saturn and its moons for 11 years now. The Wall Street Journal has a great feature that shows exactly what the probe has been looking at all that time. (Note: the video above features flashing images, so beware if that sort of thing is harmful to you.)
Randall Munroe has a new book coming out called Thing Explainer: Complicated Stuff in Simple Words in which he uses the 1000 most common English words to explain interesting mostly scientific stuff. In a preview of the book, Munroe has a piece in the New Yorker explaining Einstein's theory of relativity using the same constraint.
The problem was light. A few dozen years before the space doctor's time, someone explained with numbers how waves of light and radio move through space. Everyone checked those numbers every way they could, and they seemed to be right. But there was trouble. The numbers said that the wave moved through space a certain distance every second. (The distance is about seven times around Earth.) They didn't say what was sitting still. They just said a certain distance every second.
It took people a while to realize what a huge problem this was. The numbers said that everyone will see light going that same distance every second, but what happens if you go really fast in the same direction as the light? If someone drove next to a light wave in a really fast car, wouldn't they see the light going past them slowly? The numbers said no-they would see the light going past them just as fast as if they were standing still.
It's a fun read, but as Bill Gates observed in his review of Thing Explainer, sometimes the limited vocabulary gets in the way of true understanding:1
If I have a criticism of Thing Explainer, it's that the clever concept sometimes gets in the way of clarity. Occasionally I found myself wishing that Munroe had allowed himself a few more terms -- "Mars" instead of "red world," or "helium" instead of "funny voice air."
See also Albert Einstein's Theory of Relativity In Words of Four Letters or Less. You might prefer this explanation instead, in the form of a video by high school senior Ryan Chester:
This video recently won Chester a $250,000 Breakthrough Prize college scholarship.2 Nice work!
Michael Specter has a truly fascinating piece in the New Yorker about CRISPR, a relatively new genetic tool for editing genes that geneticists are very excited about.
With CRISPR, scientists can change, delete, and replace genes in any animal, including us. Working mostly with mice, researchers have already deployed the tool to correct the genetic errors responsible for sickle-cell anemia, muscular dystrophy, and the fundamental defect associated with cystic fibrosis. One group has replaced a mutation that causes cataracts; another has destroyed receptors that H.I.V. uses to infiltrate our immune system.
The story has everything: the cheap copy/paste of DNA, easily editable mice, pig Hitler, "destroyer of worlds" overtones, and an incredible tale of science that could actually revolutionize (or ruin, depending on who you talk to) the world. I was shocked at how easy it is to do genetic research nowadays.
Ordering the genetic parts required to tailor DNA isn't as easy as buying a pair of shoes from Zappos, but it seems to be headed in that direction. Yan turned on the computer at his lab station and navigated to an order form for a company called Integrated DNA Technologies, which synthesizes biological parts. "It takes orders online, so if I want a particular sequence I can have it here in a day or two," he said. That is not unusual. Researchers can now order online almost any biological component, including DNA, RNA, and the chemicals necessary to use them. One can buy the parts required to assemble a working version of the polio virus (it's been done) or genes that, when put together properly, can make feces smell like wintergreen. In Cambridge, I.D.T. often makes same-day deliveries. Another organization, Addgene, was established, more than a decade ago, as a nonprofit repository that houses tens of thousands of ready-made sequences, including nearly every guide used to edit genes with CRISPR. When researchers at the Broad, and at many other institutions, create a new guide, they typically donate a copy to Addgene.
And CRISPR in particular has quickened the pace. A scientist studying lung cancer mutations said of her research:
"In the past, this would have taken the field a decade, and would have required a consortium," Platt said. "With CRISPR, it took me four months to do it by myself."
Also recommended: Radiolab's podcast on CRISPR from back in June.
This is one of the freakiest atmospheric happenings I have ever seen: a fallstreak hole from Victoria, Aus.
It is believed that the introduction of large numbers of tiny ice crystals into the cloud layer sets off this domino effect of evaporation which creates the hole. The ice crystals can be formed by passing aircraft which often have a large reduction in pressure behind the wing- or propeller-tips. This cools the air very quickly, and can produce a ribbon of ice crystals trailing in the aircraft's wake. These ice crystals find themselves surrounded by droplets, grow quickly by the Bergeron process, causing the droplets to evaporate and creating a hole with brush-like streaks of ice crystals below it.
More photos of this particular hole can be found here.
Here's everything you need to know about the Earth, in a snappy 7-minute video. I am trying very hard not to watch the rest of Kurzgesagt's videos this afternoon, but I did make time for this one on the Big Bang -- key quote: "time itself becomes wibbly wobbly" -- and how evolution works.
A group in Wales is testing concrete that can heal itself. Three different techniques are being pursued:
The first technique uses shape-shifting materials, known as shape-memory polymers, to repair large cracks in concrete. When these materials are heated with a small current, they can transform into a different shape that the material has 'memorised'. The researchers believe that these materials can be embedded into concrete and used to close cracks or make them smaller.
In the second technique, researchers will pump both organic and inorganic healing agents through a network of thin tunnels in the concrete to help repair damage.
In the third technique, the team will embed tiny capsules, or lightweight aggregates, containing both bacteria and healing agents into the concrete. It is anticipated that once cracks occur, these capsules will release their cargos and, in the case of the bacteria, the nutrients that will enable them to function and produce calcium carbonate, which the researchers envisage will heal the cracks in the concrete.
Concrete-patching bacteria. Cool! (via @CharlesCMann)
Update: Dutch microbiologist Hendrik Jonkers has been working on self-healing concrete as well, with products coming to market soon.
A group called Kurzgesagt, in collaboration with author Johann Hari, made this video about taking a new approach to understanding addiction. You've probably heard of the experiments where rats in cages were given access to drugs. The rats quickly became addicted to them and used them heavily until overdosing. But perhaps the problem is not the drugs but the cage. Later experiments showed that if rats were given plenty of alternate activities, freedom, and room to roam, they were not likely to become heavy drugs users or overdose.
Human studies are more difficult to come by, but it still appears that when available, living life, family, and friends are more addictive than heroin. And so, according to Hari, who wrote a book about all this, what we should be doing is not isolating those who become addicted to drugs, alcohol, and other things. Instead, we should build a society that reconnects people to each other so that the drugs become unnecessary.
In addition to the video and the book, there's an interactive version of the video as well as an article by Hari on Huffington Post. (via @gavinpurcell)
Whoa, how have I not heard about this before today: the Cassini spacecraft is going to dive through a jet of water erupting from Enceladus, a Saturnian moon.
Discovering life was not on the agenda when Cassini was designed and launched two decades ago. Its instruments can't capture microbes or detect life, but in a couple of dozen passes through the plumes of Enceladus, it has detected various molecules associated with life: water vapor, carbon dioxide, methane, molecular nitrogen, propane, acetylene, formaldehyde and traces of ammonia.
Wednesday's dive will be the deepest Cassini will make through the plumes, only 30 miles above the icy surface. Scientists are especially interested in measuring the amount of hydrogen gas in the plume, which would tell them how much energy and heat are being generated by chemical reactions in hydrothermal vents at the bottom of the moon's ocean.
That's pretty crazy...it sounds like science fiction. NASA is doing a wonderful job producing great science with the lean budgets they are given.
Some recent science suggests that perhaps cats aren't as domesticated as some other animals like dogs, sheep, or horses.
It appears that, following the advent of agriculture, wildcats in the Near East and Asia likely began to congregate near farms and grain stores, where mice and rats were abundant. People tolerated the volunteer exterminators, and wildcats became increasingly comfortable with people. Whether this affiliation began five or ten millennia ago, the evidence suggests that cats have not been part of our domestic domain for nearly as long as dogs, which have been our companions for perhaps forty thousand years.
After all, true house cats are only 60-ish years old, dating roughly to the invention of kitty litter.
Or, as one of my favorite short talks (by Kevin Slavin) suggests, perhaps it is humans who have been domesticated by a protozoan parasite that lives within cats, which, when transmitted to humans, makes us want to share funny cat GIFs online.
A new study from scientists and economists at Stanford and Berkeley has taken a stab at determining how climate change will affect the world's economic activity. As part of their study, they look at which countries might benefit from climate change and which might lose out. As you might expect, countries in the Northern Hemisphere with cooler climates stand to benefit while the rest of the world will not. Here are some of the projected big winners (the Nordic countries) and losers (the Middle East):
Saudi Arabia -96%
United Arab Emirates -94%
Canada (+247%) is another one of the potential big winners while the US (-36%) stands to lose out...along with all of Africa, South America, India, and China. This quote by one of the study's lead authors, really grabbed me by the throat:
What climate change is doing is basically devaluing all the real estate south of the United States and making the whole planet less productive. Climate change is essentially a massive transfer of value from the hot parts of the world to the cooler parts of the world. This is like taking from the poor and giving to the rich.
Among other many things, anthropogenic climate change is an issue of discrimination.1 Rich, predominantly white countries caused the problem and can do the most to limit the damage, but climate change will disproportionately affect poor countries, poor people (even in rich countries), women, and people of color. The rich need to do something about it so that the poor will not suffer. The problem is, the world's wealthy have a long history of not being incentivized to help anyone but themselves. I hope this will turn out differently...or, as sometimes happens, the desires of the wealthy and the needs of the poor dovetail into action of joint benefit.
The scientists who conducted a study at the Delft University of Technology in the Netherlands say they have proved that quantum entanglement is a real effect.
The Delft researchers were able to entangle two electrons separated by a distance of 1.3 kilometers, slightly less than a mile, and then share information between them. Physicists use the term "entanglement" to refer to pairs of particles that are generated in such a way that they cannot be described independently. The scientists placed two diamonds on opposite sides of the Delft University campus, 1.3 kilometers apart.
Each diamond contained a tiny trap for single electrons, which have a magnetic property called a "spin." Pulses of microwave and laser energy are then used to entangle and measure the "spin" of the electrons.
The distance -- with detectors set on opposite sides of the campus -- ensured that information could not be exchanged by conventional means within the time it takes to do the measurement.
The study, published in Nature, has yet to be verified, but still, exciting!
A recent paper found that the time it takes for an animal to move the length of its own body is largely independent of mass. This appears to hold from tiny bacteria on up to whales -- that's more than 20 orders of magnitude of mass. The paper's argument as to why this happens relies on scaling laws. Alex Klotz explains.
A well-known example is the Square-Cube Law, dating back to Galileo and described quite well in the Haldane essay, On Being the Right Size. The Square-Cube Law essentially states that if something, be it a chair or a person or whatever, were made twice as tall, twice as wide, and twice as deep, its volume and mass would increase by a factor of eight, but its ability to support that mass, its cross sectional area, would only increase by a factor of four. This means as things get bigger, their own weight becomes more significant compared to their strength (ants can carry 50 times their own weight, squirrels can run up trees, and humans can do pullups).
Another example is terminal velocity: the drag force depends on the cross-sectional area, which (assuming a spherical cow) goes as the square of radius (or the two-thirds power of mass), while the weight depends on the volume, proportional to the cube of radius or the first power of mass. As Haldane graphically puts it
"You can drop a mouse down a thousand-yard mine shaft; and, on arriving at the bottom, it gets a slight shock and walks away, provided that the ground is fairly soft. A rat is killed, a man is broken, a horse splashes."
Scaling laws also come into play in determining the limits of the size of animals: The Biology of B-Movie Monsters.
When the Incredible Shrinking Man stops shrinking, he is about an inch tall, down by a factor of about 70 in linear dimensions. Thus, the surface area of his body, through which he loses heat, has decreased by a factor of 70 x 70 or about 5,000 times, but the mass of his body, which generates the heat, has decreased by 70 x 70 x 70 or 350,000 times. He's clearly going to have a hard time maintaining his body temperature (even though his clothes are now conveniently shrinking with him) unless his metabolic rate increases drastically.
Luckily, his lung area has only decreased by 5,000-fold, so he can get the relatively larger supply of oxygen he needs, but he's going to have to supply his body with much more fuel; like a shrew, he'll probably have to eat his own weight daily just to stay alive. He'll also have to give up sleeping and eat 24 hours a day or risk starving before he wakes up in the morning (unless he can learn the trick used by hummingbirds of lowering their body temperatures while they sleep).
Hopes&Fears asked a group of scientists and researchers if reality is actually real or if it's all an illusion or hallucination.
How do we know this is real life? The short answer is: we don't. We can never prove that we're not all hallucinating, or simply living in a computer simulation. But that doesn't mean that we believe that we are.
There are two aspects to the question. The first is, "How do we know that the stuff we see around us is the real stuff of which the universe is made?" That's the worry about the holographic principle, for example -- maybe the three-dimensional space we seem to live in is actually a projection of some underlying two-dimensional reality.
Astronomers are interested in the goings-on around a star in our galaxy called KIC 8462852. There appears to be a lot of debris around it, which is a bit unusual and might have any number of causes, including that an extraterrestrial intelligence built all sorts of things around the star.
Jason Wright, an astronomer from Penn State University, is set to publish an alternative interpretation of the light pattern. SETI researchers have long suggested that we might be able to detect distant extraterrestrial civilizations, by looking for enormous technological artifacts orbiting other stars. Wright and his co-authors say the unusual star's light pattern is consistent with a "swarm of megastructures," perhaps stellar-light collectors, technology designed to catch energy from the star.
"When [Boyajian] showed me the data, I was fascinated by how crazy it looked," Wright told me. "Aliens should always be the very last hypothesis you consider, but this looked like something you would expect an alien civilization to build."
Boyajian is now working with Wright and Andrew Siemion, the Director of the SETI Research Center at the University of California, Berkeley. The three of them are writing up a proposal. They want to point a massive radio dish at the unusual star, to see if it emits radio waves at frequencies associated with technological activity.
Phil Plait has more context on this weirdo star and how the alien angle is pretty far-fetched but also worth checking out.
I noted the other day that since the early 1980s, the world has lost about half of its coral reefs. According to a recent study, there's more to worry about in the sea: the ocean contains half the fish it did 45 years ago.
Professor McIntyre and his contemporaries believed that overfishing was inherently self-correcting. People might catch too much, but then they would stop fishing, letting the stock recover. They did not reckon on improvements in technology such as a monofilament line, factory trawlers, or fish finders that make it possible to catch so many fish so quickly that it can take decades for a stock to recover (if it ever does). Nor did he or his contemporaries understand food webs and ecological connections; reducing stocks of some species has more of an impact than others.
Update: Here's a PDF copy of the actual report by the WWF. (via @RachelAronson)
It's getting more difficult for new painkilling drugs to be approved because the rate of effectiveness vs. placebos in drug tests is falling. But oddly, the drop is only being seen in the US.
Based on patients' ratings of their pain, the effect of trialled drugs in relieving symptoms stayed the same over the 23-year period -- but placebo responses rose. In 1996, patients in clinical trials reported that drugs relieved their pain by 27% more than did a placebo. But by 2013, that gap had slipped to just 9%. The phenomenon is driven by 35 US trials; among trials in Europe, Asia and elsewhere, there was no significant change in placebo responses. The analysis is in press in the journal Pain.
A persistent underwater heatwave is causing corals worldwide to bleach, and scientists believe up to 5% of the world's coral will die permanently.
Hoegh-Guldberg said he had personally observed the first signs of bleaching on Australia's Great Barrier Reef in the past fortnight, months before the warm season begins. He said the warming pattern indicated bleaching this summer would likely affect 50% of the reef, leaving 5-10% of corals dead. Eakin said seeing bleaching on the reef at this time of year was "disturbing".
Also, no matter how many times I read this, it never gets less scary:
Since the early 1980s the world has lost roughly half of its coral reefs.
The oceans are slowly boiling and we're the frogs who aren't noticing. (via @EricHolthaus)
When the Curiosity rover landed on the surface of Mars, it took high-resolution photos all the way down. Luke Fitch took those photos and stitched them together into a first-person HD video of the rover's landing.
Update: I was wondering if someone had done a stabilized version of this video and lo:
That is the question that physicist Lawrence Krauss answers in his book, A Universe from Nothing. The book's trailer provides a little more context.
Everything we see is just a 1% bit of cosmic pollution in a Universe dominated by dark matter and dark energy. You could get rid of all the things in the night sky -- the stars, the galaxies, the planets, everything -- and the Universe would be largely the same.
And my favorite line from the trailer:
Forget Jesus, the stars died so you could be born.
(via open culture)
From the landmark science series Cosmos, Carl Sagan narrates the evolution of humans from the first cells billions of years ago.
NASA's press conference doesn't start for a few minutes yet, but the NY Times has the scoop: NASA has found "definitive signs" of liquid water on the surface of Mars. Like, right now on Mars, not millions of years ago.
In a paper published in the journal Nature Geoscience, Dr. McEwen and other scientists identified waterlogged molecules -- salts of a type known as perchlorates - in readings from orbit.
"That's a direct detection of water in the form of hydration of salts," Dr. McEwen said. "There pretty much has to have been liquid water recently present to produce the hydrated salt."
By "recently," Dr. McEwen said he meant "days, something of that order."
This is fantastic timing for the release of The Martian movie, which comes out this weekend.
Update: And here's the official press release from NASA.
"Our quest on Mars has been to 'follow the water,' in our search for life in the universe, and now we have convincing science that validates what we've long suspected," said John Grunsfeld, astronaut and associate administrator of NASA's Science Mission Directorate in Washington. "This is a significant development, as it appears to confirm that water -- albeit briny -- is flowing today on the surface of Mars."
These downhill flows, known as recurring slope lineae (RSL), often have been described as possibly related to liquid water. The new findings of hydrated salts on the slopes point to what that relationship may be to these dark features. The hydrated salts would lower the freezing point of a liquid brine, just as salt on roads here on Earth causes ice and snow to melt more rapidly. Scientists say it's likely a shallow subsurface flow, with enough water wicking to the surface to explain the darkening.
Artist and programmer Jeff Thompson has compiled 15,000 hand-drawn maps of the Sun made by astronomers into a single video, creating a mesmerizing and delightfully makeshift stop-motion animation of the Sun's activity over the last 43 years. Astronomers have been drawing these "solar synoptic maps" since 1956 in order to keep track of the Sun's "weather"...sunspots, flares, and the like. (via slate)
Scientists have discovered that an insect has evolved something like a gearbox to coordinate its leg movements while jumping. That's right, nature invented mechanical gears before man got around to it.
The gears in the Issus hind-leg bear remarkable engineering resemblance to those found on every bicycle and inside every car gear-box.
Each gear tooth has a rounded corner at the point it connects to the gear strip; a feature identical to man-made gears such as bike gears -- essentially a shock-absorbing mechanism to stop teeth from shearing off.
The gear teeth on the opposing hind-legs lock together like those in a car gear-box, ensuring almost complete synchronicity in leg movement -- the legs always move within 30 'microseconds' of each other, with one microsecond equal to a millionth of a second.
This is critical for the powerful jumps that are this insect's primary mode of transport, as even minuscule discrepancies in synchronisation between the velocities of its legs at the point of propulsion would result in "yaw rotation" -- causing the Issus to spin hopelessly out of control.
"This precise synchronisation would be impossible to achieve through a nervous system, as neural impulses would take far too long for the extraordinarily tight coordination required," said lead author Professor Malcolm Burrows, from Cambridge's Department of Zoology.
Edward Snowden has come up with a solution to the Fermi Paradox that I hadn't heard of before. Maybe we haven't discovered intelligent life elsewhere in the Universe, says Snowden, because their communications encryption is indistinguishable from cosmic background radiation.
"If you look at encrypted communication, if they are properly encrypted, there is no real way to tell that they are encrypted," Snowden said. "You can't distinguish a properly encrypted communication from random behaviour."
Therefore, Snowden continued, as human and alien societies get more sophisticated and move from "open communications" to encrypted communication, the signals being broadcast will quickly stop looking like recognisable signals.
"So if you have an an alien civilization trying to listen for other civilizations," he said, "or our civilization trying to listen for aliens, there's only one small period in the development of their society when all their communication will be sent via the most primitive and most unprotected means."
After that, Snowden said, alien messages would be so encrypted that it would render them unrecognisable, "indistinguishable to us from cosmic microwave background radiation". In that case, humanity would not even realise it had received such communications.
Snowden shared his hypothesis with Neil deGrasse Tyson on Tyson's podcast, StarTalk.
The backlit photos of Pluto just posted by NASA are breathtaking. Look at this:
Just 15 minutes after its closest approach to Pluto on July 14, 2015, NASA's New Horizons spacecraft looked back toward the sun and captured this near-sunset view of the rugged, icy mountains and flat ice plains extending to Pluto's horizon. The smooth expanse of the informally named Sputnik Planum (right) is flanked to the west (left) by rugged mountains up to 11,000 feet (3,500 meters) high, including the informally named Norgay Montes in the foreground and Hillary Montes on the skyline. The backlighting highlights more than a dozen layers of haze in Pluto's tenuous but distended atmosphere. The image was taken from a distance of 11,000 miles (18,000 kilometers) to Pluto; the scene is 230 miles (380 kilometers) across.
As they say, best viewed large. Some of those features don't look like mountains at all, but like reptile scales or huge shards of ice pushed up into the sky. Fantastic.
Last month I shared a video showing the thousands of nuclear weapons that humans have detonated on Earth. I hadn't really thought about it too much apart from the two dropped in Japan in WWII, but those weapons created some permanent physical changes in the landscape of the Earth. For instance, dozens of circular scars are visible at this testing range in Nevada near Area 51.
Also located in the same area is the Sedan Crater, the largest man-made crater in the United States. The crater is 320 feet deep, 1280 feet across, listed on the National Register of Historic Places, and was made by a thermonuclear device with a 104 kiloton yield detonated in 1962.
Now, I haven't read a whole lot about nuclear tests, but this one seems particularly idiotic. The purpose of the Sedan shot was not to test a new kind of weapon or to determine the effects of the bomb, but to move earth. Yeah, no big deal, we're just gonna use a fusion bomb like a big stick of dynamite. Sedan was part of Operation Plowshare, an effort to use nuclear devices for peaceful purposes like mining and moving earth. From Wikipedia:
Proposed uses for nuclear explosives under Project Plowshare included widening the Panama Canal, constructing a new sea-level waterway through Nicaragua nicknamed the Pan-Atomic Canal, cutting paths through mountainous areas for highways, and connecting inland river systems. Other proposals involved blasting underground caverns for water, natural gas, and petroleum storage. Serious consideration was also given to using these explosives for various mining operations. One proposal suggested using nuclear blasts to connect underground aquifers in Arizona. Another plan involved surface blasting on the western slope of California's Sacramento Valley for a water transport project.
The Pan-Atomic Canal! This quaint US government video has more on Sedan:
In my post the other day, I said that the Soviets didn't care about their citizenry when testing nuclear devices. Apparently the US didn't either: the Sedan shot -- the purpose of which, as a reminder, was to move a bunch of dirt -- resulted in a significant amount of nuclear fallout, about 7% of the total radioactive fallout generated by all the nuclear tests in Nevada. Fallout from the test reached as far as West Virginia and was particularly high in counties in Iowa and Illinois. Buy hey, they moved 12 million tons of soil! (via @kyledenlinger)
In retrospect, it was an unlikely set of conditions that came together to produce the Space Age. Not just the postwar blend of prosperity and paranoia, but a series of scientific breakthroughs, both pure and applied, that happened in such close succession that we nearly had a surplus, one that had to be invested in something.
We had to know our world well enough to be able to escape it, but not so well that we couldn't ignore the price we were paying. And now that window may be closing.
Here are two stories that have me in an elegiac mood. "This Used To Be the Future" is a photoessay by Rachel Sussman that looks at NASA's Ames Research Center in Silicon Valley. Most stories about Ames focus on the cutting edge stuff, the public/private partnerships; Sussman focuses on the old stuff, the military leftovers, the junk.
Next is a piece in Scientific American on plutonium-238. NASA uses the slow-burning plutonium to power its long-range probes and interplanetary craft.
Over the past half-century, NASA has used a total of 140 kilograms of Pu-238 to push the frontiers of exploration. Coupled to one of the agency's "thermoelectric" generators that convert heat into electricity, four kilograms of the stuff can power a spacecraft for decades. Pu-238 was used in Apollo-era science experiments on the Moon, in the Galileo mission to Jupiter and in the Pioneer and Voyager space probes now exiting our solar system. Hefty hunks of Pu-238 power the Mars Curiosity rover, the Cassini orbiter at Saturn and the New Horizons spacecraft now roaming beyond Pluto. In the future, Pu-238 could power robotic probes to burrow beneath the ice of ocean-bearing moons, planes to fly in the alien atmospheres of other worlds, ships to sail the liquid ethane seas of Saturn's moon Titan and much, much more.
Those future missions can only occur if there's enough plutonium to go around. Practically all of NASA's Pu-238 stockpile was made as a byproduct of building nuclear weapons during the Cold War. As the Cold War wound down, so too did the Department of Energy's Pu-238 production; it made its last batch in 1988, shutting off NASA's supply save for occasional deliveries of small, lower-quality batches from Russia that ceased in 2010. At present, only about 35 kilograms of Pu-238 are left for the space agency, and radioactive decay has rendered all but 17 kilograms too weak to be readily used in NASA's thermoelectric generators. NASA and DOE officials estimate there is only enough for four more generators, one of which is already committed to NASA's upcoming Mars 2020 rover.
The plutonium shortfall makes it impossible for NASA to plan future missions that would require it, but in the absence of specific mission needs, nobody wants to make any more. Solar-powered craft could eventually fill in the gap, but the technology's not there yet.
So the stars get further and further away.
Jonathan Hickman is currently writing Secret Wars for Marvel, but the roots of that story go back to his earlier run on Fantastic Four. There's a great scene where Reed Richards, Mister Fantastic, resigns from the Singularity Conference (think TED/O'Reilly/Davos on steroids), a group of scientists he founded, as they argue for increasingly limited approaches to exploration.
The other scientists are basically correct. It is irresponsible to fund manned space missions in a global recession. Our global population may be impossible to sustain on our planet going forward. But Mister Fantastic, being a superhero, rejects the premise. "The future of man is not one billion of us fighting over limited resources on a soon-to-be-dead planet, but one trillion human beings spanning an entire galaxy," he says. "The future of man is not here. It is out there. Because it's our new horizon. Because it's what's next."
It's a corny, Sorkin-esque speech.... but I love it. It thrills me. And it makes me afraid.
I would like to think that that time isn't over yet, that there is a way to reconcile what we know now with what we were willing to risk for the sake of knowledge then -- that if not in outer space, then in medicine or genetics or some other field. But part of me wonders if the time for us to come together to do big things -- that space age, that Marvel Age, that time of the Fantastic Four -- is over. And all that's left is how we manage our decline.
There's a new (extinct) hominin on the block (in a cave system in Africa): Homo naledi.
Basically, Homo naledi had humanlike hands, legs, and feet, but tiny little australopithecine skulls, i.e., brains.
And, there are a lot of them, fossil-wise: "Representing at least 15 individuals with most skeletal elements repeated multiple times, this is the largest assemblage of a single species of hominins yet discovered in Africa."
But we don't yet know exactly how long ago they lived: maybe two million years ago, when the Homo genus emerged, or as late as a hundred thousand years ago, when it contracted to, well, us. In an accompanying article, Chris Stringer gets a little testy about it.
Frustratingly, the rich and informative H. naledi material remains undated. Given that this hominin material could conceivably even date within the last 100,000 years, I am puzzled by the apparent lack of attempts to estimate its age. This could have been achieved directly via radiocarbon dating (even if only to test whether the material lies beyond the effective range of that method) or indirectly based on ancient DNA samples. For example, after ancient DNA was successfully recovered from the Sima de los Huesos fossils, it was used to date them to about 400,000 years old (Meyer et al., 2014). Moreover, tests on even small fragments of bone and tooth enamel could have narrowed down the possible age range and at least ruled out either a very ancient or very young age (Grün, 2006).
As Dan Cohen points out, this discovery is also unusual in that it didn't make its splash at Science or Nature, but eLife, a free, open-access journal. Study leader Lee Berger tells Buzzfeed the article was rejected by Nature because the authors couldn't meet the mag's demands to squeeze the whole thing into 2500 words. Well, whatever the reason for going open-access, we of the science-following-but-not-institutional-password-having-audience approve.
Update: Ed Yong has a terrific account of the discovery, with a ripping narrative about the caving team's expedition and an intelligent analysis of the new species and its implications. Well worth reading.
Rain-Bros by Daniel Savage is a fun visualization of the different wavelengths of light in the visible spectrum, from the loping walk of red to blue's energetic bounce.
Oliver Sacks was a champion of one of humankind's most admirable qualities: Curiosity. The neurologist and writer died on Monday. He wrote beautifully about his impending death in a piece published a couple weeks ago:
And now, weak, short of breath, my once-firm muscles melted away by cancer, I find my thoughts, increasingly, not on the supernatural or spiritual, but on what is meant by living a good and worthwhile life...
Longform has a collection of links to some of Sacks' most popular essays.
Riffing on a question Richard Feynman once posed to himself, Tom Chivers asked 12 scientists:
If, in some cataclysm, all of scientific knowledge were to be destroyed, and only one sentence passed on to the next generation of creatures, what statement would contain the most information in the fewest words?
I liked the pragmatic answer by Lewis Dartnell, author of The Knowledge: How to Rebuild Civilization in the Aftermath of a Cataclysm
While Feynman's sentence is all good and true, it isn't particularly useful in an immediate pragmatic sense. I wrote a book recently which was intended as a guidebook for rebooting civilisation after an apocalypse, looking at the key technologies and central scientific principles that underpin our lives - the behind-the-scenes fundamentals that we all just take for granted today - and what enabled society to progress through the centuries of history. I argue how the greatest invention of history is the scientific method itself - the knowledge-generation machinery that we have been using for over 350 years now to come to understand how the world works. So if you could preserve only one single sentence, I would push for: 'The natural world is not governed by whimsical gods, but is essentially mechanical and can therefore be understood and then predicted by people, using careful observation, experimentation, and measurement, and importantly by testing your explanations to try to refute them.' It's this reiterative process of refinement that sets science apart from any other system for explaining how the world works.
There are other tips that could help with immediate survival. Diarrhoeal disease kills millions of people every year - all preventable by simple means. One method recommended by the World Health Organisation in developing nations for low-tech treatment of drinking water is called SODIS, or solar disinfection. All you need to do is pour your suspect water into a plastic bottle and leave it in the sun. Ultraviolet rays in sunlight pass straight through and kill any germs. So you can come back to your bottle a day or two later and know that the water you put to your lips isn't going to kill you.
Up until very recently, humans were thought to be the only animals who made and used stone tools, an era in human development that began roughly 3.3 million years ago. But according to this piece at the BBC, some chimpanzees and monkeys in various places around the globe have been using primitive stone tools for hundreds or even thousands of years.
Boesch and his colleagues had previously studied modern chimpanzee stone tool culture in the region. This research revealed that the chimpanzees have an idiosyncratic way of choosing and using their tools.
For instance, chimpanzees will often deliberately opt for particularly large and heavy stone hammers, between 1kg and 9kg, while humans prefer to use stones that weigh 1kg or less. Many of the 4300-year-old stone tools weighed more than 1kg, suggesting they were used by chimpanzees.
Chimpanzees also use their stone tools to crack open certain types of nuts that humans don't eat. Starch residues on some of the ancient tools came from these nuts.
Together, these findings led to an obvious conclusion: chimpanzees have been using stone tools in the rainforests of Ivory Coast for at least 4300 years.
Bjorn Jonsson used the photos taken by NASA's New Horizons spacecraft to make an animation of the probe's flyby of Pluto.
The time covered is 09:35 to 13:35 (closest approach occurred near 11:50). Pluto's atmosphere is included and should be fairly realistic from about 10 seconds into the animation and to the end. Earlier it is largely just guesswork that can be improved in the future once all data has been downlinked from the spacecraft. Light from Pluto's satellite Charon illuminates Pluto's night side but is exaggerated here, in reality it would be only barely visible or not visible at all.
Fantastic...and Pluto's moons flying about in the background is the cherry on the top. (via @BadAstronomer)
In A Children's Picture-book Introduction to Quantum Field Theory, Brian Skinner explains quantum field theory -- "the deepest and most intimidating set of ideas in graduate-level theoretical physics" -- as if you and I are five-year-old children.
The first step in creating a picture of a field is deciding how to imagine what the field is made of. Keep in mind, of course, that the following picture is mostly just an artistic device. The real fundamental fields of nature aren't really made of physical things (as far as we can tell); physical things are made of them. But, as is common in science, the analogy is surprisingly instructive.
So let's imagine, to start with, a ball at the end of a spring.
How massive are they? The Sun is 1 solar mass and as wide as 109 Earths. Sagittarius A, the black hole at the center of the Milky Way, weighs 4.3 million solar masses and is as wide as Mercury is far from the Sun. The black hole at the center of the Phoenix Cluster is one of the largest known black holes in the Universe; it's 73 billion miles across, which is 19 times larger than our entire solar system (from the Sun to Pluto). As for how much it weighs, check this out:
I also like that if you made the Earth into a black hole, it would be the size of a peanut. (thx, reidar)
Emily Lakdawalla provides an update on all of the exploration that's going on in our solar system this month. Here's a quick map view of the 20+ spacecraft exploring our solar system beyond Earth:
Mars remains the most active spot beyond Earth in the solar system. This week, Mars Reconnaissance Orbiter reaches its 10th anniversary of service in space, but it's far from the oldest spacecraft in orbit at Mars; Mars Express and Mars Odyssey are still at work up there. Mars Orbiter Mission has ventured into an extended mission and is still returning photos, though apparently none of the full-disk images in a variety of phases that I had hoped for from its 4-Megapixel color camera. Even Mars' newest resident, MAVEN, is three-quarters of the way through its one-year primary science mission, which began on November 16, 2014. MAVEN's mission will undoubtedly be extended long beyond that, as it will be needed to support surface missions if and when Odyssey and Mars Reconnaissance Orbiter eventually fail.
Both Opportunity and Curiosity have been very active lately. Opportunity has finally reached Marathon Valley, a site identified from orbit to have signs of clay chemistry. The team is excited about the science prospects even though the rover's memory problems persist.
Artist Sam Van Aken is using grafting to create trees that bear 40 different kinds of fruit. National Geographic recently featured Van Aken's Tree of 40 Fruit project:
The grafting process involves slicing a bit of a branch with a bud from a tree of one of the varieties and inserting it into a slit in a branch on the "working tree," then wrapping the wound with tape until it heals and the bud starts to grow into a new branch. Over several years he adds slices of branches from other varieties to the working tree. In the spring the "Tree of 40 Fruit" has blossoms in many hues of pink and purple, and in the summer it begins to bear the fruits in sequence -- Van Aken says it's both a work of art and a time line of the varieties' blossoming and fruiting. He's created more than a dozen of the trees that have been planted at sites such as museums around the U.S., which he sees as a way to spread diversity on a small scale.
No hunger. No pollution. No disease. Wired's Amy Maxmen welcomes you to the age of copy and paste DNA editing and the end of life as we know it.
Genome editing started with just a few big labs putting in lots of effort, trying something 1,000 times for one or two successes. Now it's something that someone with a BS and a couple thousand dollars' worth of equipment can do. What was impractical is now almost everyday. That's a big deal.
[I recently listened to Radiolab's show on Crispr. Recommended. -jkottke]
A company called Oxitec has genetically modified mosquito eggs so that the mosquitos born from them pass along a gene to their offspring that prohibits the mosquitos from reaching sexual maturity and mating. They release the mosquitos into the wild, they mate with the local population of mosquitos, and those born from those matings will die before mating themselves. Voila! Pest control.
Oxitec has conducted trials with its modified mosquito in dengue-ridden regions of Panama, Brazil, Malaysia, and the Cayman Islands. The results show population suppression rates above 90 percent-far greater than the typical 30 percent achieved with insecticides.
The company is currently planning a trial in Florida using this technique to curb an influx of mosquito-borne illness.
This morning, the New Horizons probe zinged safely1 past Pluto. Before it did, it transmitted the best photo we've seen of Pluto so far...the last one we'll get before we get the really good stuff. Look at this:
The probe's "I'm OK!" message will reach Earth around 9pm ET tonight and we'll start seeing photos from the flyby Wednesday afternoon...there's a NASA press conference scheduled for 3pm ET on July 15. So exciting!
Update: The photo above is also the best full-disk image of Pluto that we will get...the rest will be close-ups and such. So that's the official Pluto portrait from now on, folks.
CERN's LHC (Large Hadron Collider) has discovered a new subatomic particle, the pentaquark.
"The pentaquark is not just any new particle," said LHCb spokesperson Guy Wilkinson. "It represents a way to aggregate quarks, namely the fundamental constituents of ordinary protons and neutrons, in a pattern that has never been observed before in over fifty years of experimental searches. Studying its properties may allow us to understand better how ordinary matter, the protons and neutrons from which we're all made, is constituted."
Here's the paper, with more than 680 authors. Between New Horizons zipping past Pluto earlier today (look at this pic!) and this, what a day for science.
Psychologists Dacher Keltner and Paul Ekman served as scientific consultants during the production of Pixar's Inside Out. Keltner studies the origins of human emotion and Ekman pioneered research of microexpressions. In this NY Times piece, they discuss the science behind the movie.
Those quibbles aside, however, the movie's portrayal of sadness successfully dramatizes two central insights from the science of emotion.
First, emotions organize -- rather than disrupt -- rational thinking. Traditionally, in the history of Western thought, the prevailing view has been that emotions are enemies of rationality and disruptive of cooperative social relations.
Second, emotions organize -- rather than disrupt -- our social lives. Studies have found, for example, that emotions structure (not just color) such disparate social interactions as attachment between parents and children, sibling conflicts, flirtations between young courters and negotiations between rivals.
I've thought about Inside Out every day since I saw it. Pixar clearly did their homework on the emotional stuff and it paid off.
As the New Horizons probe nears Pluto, I've been reading a bit more about how it's going to work and what sort of photos we're going to get. Emily Lakdawalla has a comprehensive post about what to expect when you're expecting a flyby of Pluto. The post contains an image of approximations of the photos New Horizon will take, using Voyager images of Jovian and Saturnian moons as stand-ins. The highest resolution photo of Pluto will be 0.4 km/pixel...it'll have this approximate level of detail:
Which is pretty amazing and exciting considering that before the mission started this was our best view of Pluto:
NASA's Eyes app lets you see a simulation of the probe as it approaches Pluto, but if you don't want to download anything, you can watch this video of the flyby instead:
I had no idea the probe spun around so much as it grabs photos & scans and then beams them back to Earth. And the flyby is so fast! New Horizons is currently moving at 32,500 mph relative to the Sun...it's travelling just over 9 miles every second. (via @Tim_Meyer_ & @badastronomer)
Pluto is so far away that we haven't even been able to get a good look at it, not even with the crazy-powerful Hubble telescope. But with NASA's New Horizons mission closing in on our solar system' ninth planet,1 we are getting a better and better view of Pluto every day.1Here's the latest, from just a few hours ago:
New Horizons will reach its closest approach to Pluto in just under 6 days, on July 14. The probe will pass within 7,800 miles of the surface...I can't wait to find out what that day's photos look like.
Update: You don't even need to wait until tomorrow for that better image...here's one that NASA released just a short while ago. Tune in tomorrow for an even better view.
Unlike the Earth, Mars and the Moon don't have strong directional magnetic fields, which means traditional compasses don't work. So how did the Apollo rovers and current Mars rovers navigate their way around? By using manually set directional gyroscope and wheel odometers.
While current un-crewed rovers don't have to return to the comfort of a lunar module, some aspects of the Apollo systems live on in their design. Four U.S. Martian rovers have used wheel odometers that account for slippage to calculate distance traveled. They've also employed gyroscopes (in the form of an inertial measurement units) to determine heading and pitch/roll information.
One of the fun things about reading The Martian is you get to learn a little bit about this sort of thing. Here's a passage about navigation on Mars where astronaut Mark Watney is trying to get to a landmark several days' drive away.
Navigation is tricky.
The Hab's nav beacon only reaches 40 kilometers, so it's useless to me out here. I knew that'd be an issue when I was planning this little road trip, so I came up with a brilliant plan that didn't work.
The computer has detailed maps, so I figured I could navigate by landmarks. I was wrong. Turns out you can't navigate by landmarks if you can't find any god damned landmarks.
Our landing site is at the delta of a long-gone river . NASA chose it because if there are any microscopic fossils to be had, it's a good place to look. Also, the water would have dragged rock and soil samples from thousands of kilometers away. With some digging, we could get a broad geological history.
That's great for science, but it means the Hab's in a featureless wasteland.
I considered making a compass. The rover has plenty of electricity, and the med kit has a needle. Only one problem: Mars doesn't have a magnetic field.
So I navigate by Phobos. It whips around Mars so fast it actually rises and sets twice a day, running west to east. It isn't the most accurate system, but it works.
I wonder why the rovers in the story weren't outfitted with directional gyroscopes and wheel odometers? (See also the operations manual for the lunar rovers.) (via @JaredCrookston)
Here's something that I knew as a kid but had forgotten about: if you get a bike going on its own at sufficient speed, it will essentially ride itself. MinutePhysics investigates why that happens.
Interesting that the bike seems to do much of the work of staying upright when it seems like the rider is the thing that makes it work. (via devour)
While reading this otherwise excellent article written by US soccer player Christie Rampone, I discovered a type of diet I'd never heard of before, the blood type diet (italics mine).
Age and parenting make me think about longevity. I definitely believe one big reason for my longevity has to do with the dietary and fitness changes I made after being diagnosed with auto-immune conditions after giving birth to my youngest daughter Reece in 2011. For example, I've gone gluten-free and have started to eat to my blood-type. Also, a friend introduced me to a natural ingredient called EpiCor to help strengthen my immune system. I have taken EpiCor daily for the past three years and it has become a beneficial part of my daily routine of rest, recovery, working out, eating healthy, and being in airports and hotels more than my own house.
From Wikipedia, an overview of the diet:
The underlying theory of blood type diets is that people with different blood types digest lectins differently, and that if people eat food that is not compatible with their blood type, they will experience many health problems. On the other hand, if a person eats food that is compatible, they will be healthier.
That theory is, in turn, based on an assumption that each blood type represents a different evolutionary heritage. "Based on the 'Blood-Type' diet theory, group O is considered the ancestral blood group in humans so their optimal diet should resemble the high animal protein diets typical of the hunter-gatherer era. In contrast, those with group A should thrive on a vegetarian diet as this blood group was believed to have evolved when humans settled down into agrarian societies. Following the same rationale, individuals with blood group B are considered to benefit from consumption of dairy products because this blood group was believed to originate in nomadic tribes. Finally, individuals with an AB blood group are believed to benefit from a diet that is intermediate to those proposed for group A and group B."
As you might have already guessed, there is no evidence that eating your blood type is beneficial nor do the claims of differing lectin digestion have scientific merit. Homeopathic nonsense.
Tasha Sturm, a lab technician at Cabrillo College, had her 8-year-old son put his handprint on a prepared petri dish and then incubated it for several days. This was the result:
If you'll excuse me, I have to go wash my hands about 4,000 times. Bacteria is cooooool though:
Because of climate change and other activities caused by humans (invasive species, habitat loss), hybridization of species is resulting in things like super-sized coyotes, pizzly bears (grizzly/polar bear hybrids), and other animals that may not be ideally suited to survive.
Some scientists and conservationists see the coywolf as a nightmare of the Anthropocene -- a poster child of mongrelization as plants and animals reshuffle in response to habitat loss, climate change and invasive species. Golden-winged warblers increasingly cross with blue-winged warblers in the U.S. Northeast and eastern Canada. Southern flying squirrels hybridize with northern flying squirrels as the southern species presses northward in Ontario. Polar bears mate with grizzlies in the Canadian Arctic along the Beaufort Sea to produce "pizzly bears."
All of this interbreeding upsets the conventional notion of species as discrete, inviolable entities. Moreover, some scientists and conservationists warn that hybridization will degrade biodiversity as unusual species are lost to genetic homogenization.
Partly scientists fear hybrids will be less fit than organisms that have evolved in place over eons. And often that is true, but the problem solves itself over time as hybrids lose out in the competitive race for survival.
University of Minnesota student Daniel Crawford and geography professor Scott St. George have collaborated on a piece of music called Planetary Bands, Warming World. Composed for a string quartet, the piece uses climate change data to determine the musical notes -- the pitch of each note is tuned to the average annual temperature, which means as the piece goes on, the musical notes get higher and higher.
Researchers using the Keck Observatory have discovered a new kind of galaxy that are large but filled with relatively few stars.
"If the Milky Way is a sea of stars, then these newly discovered galaxies are like wisps of clouds", said van Dokkum. "We are beginning to form some ideas about how they were born and it's remarkable they have survived at all. They are found in a dense, violent region of space filled with dark matter and galaxies whizzing around, so we think they must be cloaked in their own invisible dark matter 'shields' that are protecting them from this intergalactic assault."
The night sky in such galaxies would look a lot like our skies do in large cities:
"If there are any aliens living on a planet in an ultra-diffuse galaxy, they would have no band of light across the sky, like our own Milky Way, to tell them they were living in a galaxy. The night sky would be much emptier of stars," said team member Aaron Romanowsky, of San Jose State University.
If you hold a lit match an inch or two over the smoking wick of a recently extinguished candle, the candle will light again. If you record that happening with a high speed camera and then slow it way down, it gives you some clues to how that happens:
Hint: wax is a candle's fuel and smoke is wax vapor... (via digg)
Here's a video of a titanium bar being anodized...it cycles through several different colors before settling on a pinkish hue.
Ok neat, but why does it do that? Anodizing is an adjustment of the oxide levels on the surface of the titanium. The colors are caused by the interference of the light traveling through the oxide and reflecting off the shiny metal surface underneath...different thicknesses produce different colors.1 As the voltage is applied to the metal, more and more oxide builds up, producing the color cycling even shown. Pretty cool!
From juice cleanses to vaccines to gluten to exercise to, uh, vagina steaming, celebrities like Jenny McCarthy and Gwyneth Paltrow are often found making claims that have little or no scientific evidence behind them. Timothy Caulfield recently wrote a book exploring the world of celebrity pseudoscience called Is Gwyneth Paltrow Wrong About Everything?
But while much has been written about the cause of our obsession with the rich and famous, Caulfield argues that not enough has been done to debunk celebrity messages and promises about health, diet, beauty, or the secret to happiness. From the obvious dangers, to body image of super-thin models and actors, or Gwyneth Paltrow's enthusiastic endorsement of a gluten free-diet for almost everyone, or Jenny McCarthy's ill-informed claims of the risks associated with vaccines, celebrity opinions have the power to dominate our conversations and outlooks on our lives and ourselves.
Julia Belluz of Vox interviewed Caulfield about the book.
JB: So is Gwyneth actually wrong about everything?
TC: It's incredible how much she is wrong about. Even when she is right about stuff -- like telling people to eat more fruits and vegetables -- there is always a bit of a tinge of wrongness. She'll say, "It has to be organic," for example. She is still distracting us with these untrue details, as opposed to just pushing the honest truth.
See also Your detoxing juice cleanse is bullshit.
Update: I had forgotten about this book, so I was pleased to be reminded of it by this recent interview with Caulfield about celebrity health advice.
Colon cleanse: There is no evidence we need to cleanse our colons or detoxify our bodies. Vagina steaming to detoxify and increase fertility: again, absolutely ridiculous. Getting stung by bees is her latest thing for anti-aging -- because, yes, anaphylaxis is so revitalizing. Goop, her website, suggested wearing a bra can cause cancer. This is raising fears, completely science free. I could go on and on and on.
Do you think you could ride a bicycle that steers backwards...aka it turns left when you turn right and vice versa? It sounds easy but years of normal bike riding experience makes it almost impossible. Destin Sandlin of Smarter Everyday taught himself how to ride the backwards-steering bike; it took months. Then he tried riding a normal bicycle again...
Loved this video...great stuff. (via ★interesting)
After years of the Flintstones lying to me, I'd just gotten used to the idea of the Brontosaurus not actually being a dinosaur. But a recent study of the classifications given to various species and genera within the diplodocid group of dinosaurs has determined that the Brontosaurus and the Apatosaurus are different enough to be two separate species.
Very broadly, their tree confirmed established ideas about the evolutionary relationships among diplodocids. But the scientists also concluded that Apatosaurus and Brontosaurus were different enough to belong in their own genera. Many of the anatomical differences between the two dinosaurs are obscure, Tschopp says, but Apatosaurus's stouter neck is an obvious one. "Even though both are very robust and massive animals, Apatosaurus is even more so," he adds.
Tschopp and his team thought very carefully about their decision to reinstate Brontosaurus, and they expect some pushback. "We knew it would be a major finding because Brontosaurus is such a popular name," he says. "I'm pretty sure there will be a scientific discussion around this. I hope there will be. That's how science works."
Huzzah! Now reinstate Pluto to full planetary status and we'll be all set. See also The Kindly Brontosaurus. (via @coudal)
In 1983, the BBC aired a six-part series called Fun to Imagine with a simple premise: put physicist Richard Feynman in front of a camera and have him explain everyday things. In this clip from one of the episodes, Feynman explains in very simple terms what fire is:
So good. Watch the whole thing...it seems like you get the gist about 2 minutes in, but that's only half the story. See also Feynman explaining rubber bands, how trains go around curves, and how magnets work.
James Krupa teaches a mandatory biology class at the University of Kentucky and some students have a difficult time because Krupa refuses to shy away from evolution.
Rarely do I have a Kentucky student who learned about human evolution in high school biology. Those who did usually attended high schools in large urban centers like Louisville or Lexington. Given how easily it can provoke parents, the teaching of human evolution is a rarity in high school, so much so in Kentucky that it startled me when I first arrived.
The story of our evolutionary history captivates many of my students, while infuriating some. During one lecture, a student stood up in the back row and shouted the length of the auditorium that Darwin denounced evolution on his deathbed -- a myth intentionally spread by creationists. The student then made it known that everything I was teaching was a lie and stomped out of the auditorium, slamming the door behind him. A few years later during the same lecture, another student also shouted out from the back row that I was lying. She said that no transitional fossil forms had ever been found -- despite my having shared images of many transitional forms during the semester. Many of her fellow students were shocked by her combativeness, particularly when she stormed out, also slamming the door behind her. Most semesters, a significant number of students abruptly leave as soon as they realize the topic is human evolution.
I personally don't understand the compatibility of evolutionary biology and Christianity Krupa emphasizes in his class, but I guess it helps to meet people halfway?