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.”
Other quibble: I would have called Einstein the time doctor. [cue Tardis noise]↩
Which reminds me of when I was a high school senior and I showed a clip of Bill & Ted’s Excellent Adventure to my physics class for a report on time travel and wormholes. It’s been all downhill for me since then.↩
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.”
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.
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.
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.
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.
I started to research my book, Lost Connections: Uncovering The Real Causes of Depression — and the Unexpected Solutions, because I was puzzled by two mysteries. Why was I still depressed when I was doing everything I had been told to do? I had identified the low serotonin in my brain, and I was boosting my serotonin levels — yet I still felt awful. But there was a deeper mystery still. Why were so many other people across the western world feeling like me? Around one in five US adults are taking at least one drug for a psychiatric problem. In Britain, antidepressant prescriptions have doubled in a decade, to the point where now one in 11 of us drug ourselves to deal with these feelings. What has been causing depression and its twin, anxiety, to spiral in this way? I began to ask myself: could it really be that in our separate heads, all of us had brain chemistries that were spontaneously malfunctioning at the same time?
Update: Kurzgesagt deleted this video from their channel. You can view the deleted video (they gave people permission to repost it) and hear why they deleted it. As for Hari’s view on addiction, neuroscientist Dean Burnett addresses the controversy in a pairof posts for The Guardian and there are others within the east reach of a quick Googling.
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.
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.
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):
Mongolia +1413%
Finland +516%
Iceland +513%
Russia +419%
Estonia +259%
Saudi Arabia -96%
Kuwait -96%
Oman -94%
United Arab Emirates -94%
Iraq -93%
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.
In fact, with no offense to those who rightly rail against causes of discrimination around the world, I would go so far to say that this is by far the largest and most important discriminatory issue the world faces today. Climate change will permanently remake the entire world and its economy, and the poor, women, and people of color stand to lose huge.↩
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.”
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).
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.
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.
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.
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.
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.
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.
“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.
“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.
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.
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…
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?
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.
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