SpaceX’s ambitious Starlink project could eventually launch more than 10,000 satellites into orbit and rewrite the future of the internet. But Elon Musk’s company has been taking heat from the astronomical community after an initial launch in late May released the first 60 satellites. The 500 pound (227 kg) satellites were clearly visible in Earth’s night sky, inspiring concern that they could increase light pollution, interfere with radio signals, and contribute to the growing issue of space debris.
This week, the American Astronomical Society, the International Astronomical Union, the British Royal Astronomical Society, and the International Dark-Sky Association (IDA) all issued statements expressing concern about Starlink’s potential to damage astronomical research by leaving bright streaks through images.
“The Starlink affair has raised the attention of the astronomy community in a way that I’ve not seen during my couple of decades in it,” says John Barentine, director of public policy at the IDA, which lobbies against light pollution. “I hope that this moment is the wake-up call that is needed to prompt a new discussion in the international community about the nature of outer space, especially near the Earth, in a commercial context.”
Musk had repeatedly assured people on Twitter that his satellites wouldn’t be visible at night, so the light caught some people by surprise. However, the satellites’ initial brightness is intended to wane as they climb higher into their permanent orbits.
“The observability of the Starlink satellites is dramatically reduced as they raise orbit to greater distance and orient themselves with the phased array antennas toward Earth and their solar arrays behind the body of the satellite,” a spokesperson for SpaceX said in an email.
But Barentine and other astronomers aren’t so sure, especially given that this is only the beginning for Starlink. Plus, many other companies — including Amazon, Boeing, OneWeb, Telesat, LeoSat, and even Facebook — are planning other so-called “mega-constellations” for connecting the masses online.
“There are billions of people around the world who lack access to broadband internet,” a spokesperson for Amazon’s Project Kuiper said in an email. “Our vision is to provide low-latency, high-speed broadband connectivity to many of these unserved and underserved communities around the world … Many of our satellite and mission design decisions are, and will continue to be, driven by our goals of ensuring space safety and taking into account concerns about light pollution.”
But there are already 22,000 artificial objects currently in orbit. And as the microlaunch space race kicks into high gear, that number is destined to double. Communications satellites aren’t the only things headed up, either. One group even proposed launching orbiting billboards that would shine ads back down to Earth. And an artist recently launched the “Humanity Star” – a purely artistic light beacon.
“Space is already crowded, and roughly doubling the number of objects in low- and near-Earth orbit will only add to the visual pollution of the night sky,” Barentine says. “Being in a dark place and seeing one satellite fly over every few minutes is one thing. But seeing literally dozens of them at any given time for hours every night is another story entirely.”
Part of the reason this problem stands to get worse, according to astrophysicist Laura Forczyk, is “there is no regulatory body in the United States that directs companies as to the kind of light pollution or the brightness of satellites. This is a fairly new topic and as always the government regulations are behind technology.”
But Forczyk, owner of the space consulting firm Astralytical, also says that changing the night skies isn’t the same thing as losing the night sky — and it’s a little too early to know what the total impact is going to be. After all, the Starlink satellites still haven’t reached their final orbit. “We’re very reactive when it comes to these kinds of things,” she says, but emphasizes miscommunication from both sides.
Whether the problem stands to worsen or not, most experts see the growth of these mega-constellations as inevitable.
“I don’t think we’re going to be able to create political will to stop the satellites because there is so much commercial potential and politicians tend to respond to economics,” says Phil Metzger, a planetary scientist at the University of Central Florida and a former NASA physicist. However, he says future designs of satellites can ensure they’ll cause less interference with on-the-ground astronomy.
“We can change the surface of the spacecraft so it is more absorptive and less reflective or we can even make it more transparent,” Metzger says. “We do have the ability to make electrical conductors completely transparent so we don’t need metal. You could have glass with transparent conductors in the glass … I think we’ll probably be doing all of these things in the future.”
Two trophy skulls, recently discovered by archaeologists in the jungles of Belize, may help shed light on the little-understood collapse of the once powerful Classic Maya civilization.
The defleshed and painted human skulls, meant to be worn around the neck as pendants, were buried with a warrior over a thousand years ago at Pacbitun, a Maya city. They likely represent gruesome symbols of military might: war trophies made from the heads of defeated foes.
Both skulls are similar to depictions of trophy skulls worn by victorious soldiers in stone carvings and on painted ceramic vessels from other Maya sites.
Drilled holes likely held feathers, leather straps or both. Other holes served to anchor the jaws in place and suspend the cranium around the warrior’s neck, while the backs were sawed off to make the skulls lie flat on the wearer’s chest.
Flecks of red paint decorate one of the jaws. It’s carved with glyphic writing that includes what my collaborator Christophe Helmke, an expert on Maya writing, believes is the first known instance of the Maya term for “trophy skull.”
What do these skulls — where they were found and who they were from — tell us about the end of a powerful political system that thrived for centuries, covering southeastern Mexico, all of Guatemala and Belize, and portions of Honduras and El Salvador? My colleagues and I are thinking about them as clues to understanding this tumultuous period.
The vast Maya empire flourished throughout Central America, with the first major cities appearing between 750 and 500 B.C. But beginning in the southern lowlands of Guatemala, Belize and Honduras in the eighth century A.D., people abandoned major Maya cities throughout the region. Archaeologists are fascinated by the mystery of what we call “the collapse” of this once powerful empire.
Earlier studies focused on identifying a single cause of the collapse. Could it have been environmental degradation resulting from the increasing demands of overpopulated cities? Warfare? Loss of faith in leaders? Drought?
All of these certainly took place, but none on its own fully explains what researchers know about the collapse that gradually swept through the landscape over the course of a century and a half. Today, archaeologists acknowledge the complexity of what happened.
Clearly violence and warfare contributed to the end of some southern lowland cities, as evidenced by quickly constructed fortifications identified by aerial LiDAR surveys at a number of sites.
Trophy skulls, together with a growing list of scattered finds from other sites in Belize, Honduras and Mexico, provide intriguing evidence that the conflict may have been civil in nature, pitting rising powers in the north against the established dynasties in the south.
Ceramic vessels found alongside the Pacbitun warrior and his (or her – the bones were too fragmentary to confidently determine sex) trophy skull date to the eighth or ninth century, just prior to the site’s abandonment.
During this period, Pacbitun and other Maya cities in the southern lowlands were beginning their decline, while Maya political centers in the north, in what is now the Yucatan of Mexico, rose to dominance. But the exact timing and nature of this power transition remains uncertain.
In many of these northern cities, art from this period is notoriously militaristic, abounding with skulls and bones and often showing war captives being killed and decapitated.
At Pakal Na, another southern site in Belize, a similar trophy skull was discovered inscribed with fire and animal imagery resembling northern military symbolism, suggesting a northern origin of the warrior it was buried with. The presence of northern military paraphernalia in the form of these skulls may point to a loss of control by local leaders.
Archaeologist Patricia McAnany has argued that the presence of northerners in the river valleys of central Belize may be related to the lucrative trade of cacao, the plant from which chocolate is made. Cacao was an important ingredient in rituals, and a symbol of wealth and power of Maya elites. However, the geology of the northern Yucatan makes it difficult to grow cacao on a large scale, necessitating the establishment of a reliable supply source from elsewhere.
At the northern site of Xuenkal, Mexico, Vera Tiesler and colleagues used strontium isotopes to pinpoint the geographic origin of a warrior and his trophy skull. He was local from the north. But the trophy skull he brought home, found atop his chest in burial, was from an individual who grew up in the south.
Other evidence at a number of sites in the southern highlands seems to mark a sudden and violent end for the community’s ruling order. Archaeologists have found evidence for the execution of one ruling family and desecration of sacred sites and elite tombs. At the regional capital site of Tipan Chen Uitz, approximately 20 miles (30 kilometers) east of Pacbitun, my colleagues and I found remains of several carved stone monuments that seem to have been intentionally smashed and strewn across the front of the main ceremonial pyramid.
Archaeologists are not only interested in identifying the timing and the social and environmental factors associated with collapse, which vary in different regions. We’re also trying to figure out how specific communities and their leaders responded to the unique combinations of these stresses they faced.
While the evidence from just a handful of trophy skulls does not conclusively show that sites in parts of the southern lowlands were being overrun by northern warriors, it does at least point to the role of violence and, potentially, warfare as contributing to the end of the established political order in central Belize.
These grisly artifacts lend an intriguing element to the sweep of events that resulted in the end of one of the richest, most sophisticated, scientifically advanced cultures of its time.
Every spring, farmers across the Midwest take to the fields to plant their crops. Here, corn and soybeans will reign supreme over tens of millions of acres, as soon as conditions are right to plant. Not too wet, not too dry – just right.
But the U.S. had an exceptionally wet winter this year. And it kept raining in the spring. April turned to May, and it kept raining. May turned to June, and, well, you get the picture. The past 12 months in the U.S. have been the wettest on record.Read More
Worldwide, people drink over 65 billion gallons of alcohol each year. The United States’ share, if divided equally across the adult population, would amount to about two and a half gallons of pure alcohol per person, annually. And this thirst seems to be universal: Fermented beverages have been found in nearly every society, as far back as archaeologists can detect their existence.
That’s the idea behind the “drunken monkey” hypothesis, formulated by biologist Robert Dudley in 2000.
According to the hypothesis, our pre-human ancestors regularly ingested small amounts of alcohol because the substance is produced when ripe fruit or nectar is decomposed by wild yeast. Through natural fermentation, yeast feeds on plant sugars and produces waste products of CO2 and ethanol — the chemical name for alcohol.Read More
Many marathon runners know the boost that can come from popping a mid-race energy gel. (Mmmm, calorie-rich goop.) But according to new research published in Science Advances, when it comes to endurance events, there’s a limit to how much energy the human body can draw from breaking down, or metabolizing, food. That metabolic limit depends on how long whatever tortu… — err, event you’re enduring lasts. But importantly, after a certain point in time, it plateaus, suggesting humans have a universal cap for how much energy their bodies can absorb.Read More
Before the brewpub there was the brew cave.
In Israel’s Raqefet Cave archaeologists recently reported traces of what could be the earliest known beer production 13,000 years ago.
The evidence comes from three stone mortars, analyzed in a 2018 Journal of Archaeological Science: Reports paper. After extracting residues from the rocks, the researchers identified plant molecules, including wheat or barley starches that appeared malted, mashed and fermented — the main ingredients and basic steps of beer brewing. The team also analyzed microscopic scratches and polishing on the stones. Two of the mortars had patterns indicative of plant storage and the other seems to have been used for pounding food with a wooden pestle.
If the interpretation is correct, this would push evidence for alcohol production or fermentation back several millennia. In 2012 researchers found “not fully conclusive” chemical traces of beer production in ~10,000-year-old limestone basins at the site of Göbekli Tepe, Turkey. Analysis of those vats is ongoing. But convincing booze dates to roughly 8,000 years ago, as attested by chemical markers in pottery from both China and the Caucasus mountains in the Middle East, between the Black and Caspian Seas. The preserved molecules suggest the Chinese were fermenting a brew of rice, honey and fruit, while the Middle Easterners were making grape wine.
Though the list of possible ingredients is long, scholars classify alcoholic beverages into beer —made from starches that must be broken into sugars before fermentation — and wine, which is made from sugars like fruit or honey that can be directly fermented. During fermentation, certain microbes, particularly yeasts of the Saccharomyces type, feed on the sugar, producing CO2 and ethanol, or drinkable alcohol. Hard liquor like whiskey or vodka requires the additional step of distillation, using evaporation to purify the ethanol into a higher concentration. The origins of this process are unclear, but ancient Greeks and Arabs distilled alcohol originally for medicine and perfume. Drinking spirits seems to have become popular in 16th century Europe.
Raqefet Cave seems like an odd spot for a brewery 13,000 years ago. On a steep hillside about 10 miles from the Mediterranean, the cave at this time was used as a cemetery, containing the remains of at least 29 men, women and children. The researchers suggest the beer remnants found there may have come from funerary rituals to venerate the dead.
Furthermore, these ancient brewers must have relied on wild cereals, because wheat and barley were not domesticated in the Near East until several thousand years later.
But some scholars don’t find this surprising. In fact, archaeologists have long entertained the possibility that cereals were made into beer long before they were farmed for food. A scholarly debate in 1953 asked “Did Man Once Live by Beer Alone?” and suggested that selectively picking plants for beer led to the origins of agriculture in the Near East “cradle of civilization.”
At that time the debate was speculative, because tangible traces of alcohol use could not be seen in the archaeological record. Yes, modern booze has a long shelf life, but bulk alcohol has not survived since the dawn of civilization.
Our ability to detect ancient alcohol changed in recent decades, as scientists developed tools to recover microscopic plant remains and biomolecules from artifacts and fossils. In recent years we’ve found traces of alcohol or its raw ingredients from numerous archaeological cultures, including wine in ancient Armenia ~6000 years ago, Nordic grog made from honey, fruit and cereals from ~1500 BC and corn beer from the Lake Titicaca region in the South American Andes from ~800 BC.
The diversity of ages and regions make clear that alcohol was independently discovered in many societies across the world, using native plants and technology. In different cultures, alcohol was imbibed as a source of nutrition, during rituals and for merrymaking, just as it is today.
By combining results from molecular analyses with ancient texts, artistic depictions and traditional recipes for alcohol, researchers have reconstructed many ancient brews.
In the Inca Empire of the Andes, the main alcoholic drink was corn beer of usually less than 5 percent ABV, called chicha in Spanish or aqa in native Quechua. The Aztecs of Mesoamerica made pulque from agave juice, also at around 5 percent ABV. In ancient Mesopotamia and Egypt, barley and emmer wheat beer of 3 to 6 percent was consumed daily at meals, and was likely a major source of nutritional calories, while wine of 8 to 14 percent was consumed by elites or on special occasions. Sub-Saharan Africa has traditional alcoholic beverages, still consumed today, made from cereals, bananas, palm sap and honey, though less is known about their origins.
And the ancient ABV award probably goes to East and South Asia where, since before written history, rice-based drinks like Japanese sake likely hit 10 to 20 percent.
Public interest in the science of powerful psychoactive drugs is at an-all-time, er, high. Evidence for the therapeutic benefits of marijuana, MDMA, psilocybin and more is growing, based on a resurgence of scientific interest in studying these compounds.
But many of these drugs are strictly banned by the federal government, and those caught with them on the street can face steep fine and felony prison time. So where are researchers getting the drugs for their studies?
With the bill of a duck, the body of an otter, and the tail of a beaver, the platypus (Ornithorhynchus anatinus) has a long history of confounding the humans who’ve encountered it. Early European settlers took to calling the strange, semi-aquatic mammals they found living in eastern Australian streams “duckmoles.” When Captain John Hunter, the second governor of the New South Wales colony, sent a specimen of the creature to British naturalist George Shaw in 1798, Shaw initially thought it was a hoax. Thus ensued “a rivalry that pitted nation against nation, naturalist against naturalist, and professional against amateur,” wrote evolutionary biologist Brian K. Hall in a 1999 BioScience article on the history of scientific debate over the species. “Long after the evidence was wrested from Nature half a world away from where the debate raged, biologists continued to argue about this paradoxical creature.”
For much of the two centuries since Western scientists began trying to make sense of this furry egg-laying animal — which shares its reproductive strategy with only one other mammal, the echidna — the scientific literature amounted to little more than descriptions of its odd looks, historical accounts of sightings in this river or that, and cursory observations about its anatomy and life history. That’s largely because, unlike other iconic Australian species like the slow-moving, tree-hugging koala or the ubiquitous kangaroo, platypuses are maddeningly difficult to study. Active at night and living much of their lives underwater, their habits are the opposite of their human observers’. “And beyond that,” says Geoff Williams of the Australian Platypus Conservancy, “everything you typically use in research, you can’t use with the platypus. You can’t look for tracks, and they defecate in the water, so you can’t look for scat.”
Despite those formidable challenges, over the past 20 years, a few determined scientists — aided by technological advances such as acoustic trackers and environmental DNA (bits of genetic information that an animal sheds into its surroundings) — have begun to illuminate the platypus’s world like never before. The more researchers learn about the species’ life history, whereabouts, and habitat, though, the more they realize just how much of a threat humans pose to its long-term survival.
“The biggest thing we’re learning is that platypuses are in trouble,” says Joshua Griffiths, a biologist for an environmental consulting firm on the outskirts of Melbourne who has spent many sleepless nights capturing platypuses in area streams to learn more about the secretive animals. While some populations are faring well, these tend to be in remote, wild areas. Where the human imprint has altered the platypus’s native waterways, habitat fragmentation, water pollution, fishing nets, dams, and urban development have pushed many populations into decline, Griffiths says.
Yet many of the same insights into the platypus’s status and the threats it faces have also begun to illuminate a path toward recovery that could spare the species the grim fate that so many of Australia’s other endemic creatures have met. In a country with the world’s highest mammal extinction rate, platypuses could defy the odds — if there’s enough public and political will to protect them.
Platypuses — called mallangong, tambreet, and boonaburra by Aboriginal groups who once hunted them for food — live in waterways across much of eastern Australia, including the island state of Tasmania. They are well equipped for the life aquatic. Propelling themselves through the water with wide, webbed feet, the carnivores use their much-discussed bills, packed with electrosensors, to locate and catch small prey hidden in the mud and turbid water. After stuffing their squirrel-like cheeks with food, they surface to eat. And they eat a lot: Adult platypuses spend about 12 hours a day foraging, and consume up to 30 percent of their body weight in insects, worms, crayfish, and other invertebrates each day.
“There are mammals that can live in [fresh]water and can swim well, but nothing comes close to the platypus’s ability to navigate waterways and use its super-sensitive bill to find prey,” says Richard Kingsford, a conservation biologist with the University of New South Wales who has studied the species for years.
What Kingsford, Griffiths, and other researchers have learned has certainly confirmed the platypus’s reputation as one of the world’s strangest animals. For example, scientists suspect that the venomous spurs that males are born with on their hind legs may be used as weapons against rivals during the breeding season. After mating, females retreat to the safety of a burrow they’ve excavated into the riverbank. There they lay one or two eggs and incubate them under their wide tails. While it takes only about 10 days for the eggs to hatch, mothers then nurse their young for up to four months until they’re developed enough to venture outside the burrow and forage for themselves.
Gathering even the most basic information about platypuses has required tremendous dedication. Researchers often spend hours standing in streams waiting for the nocturnal animals to appear, and all-night watches are not uncommon. To catch them, they set tunnel-like traps—netting stretched across a series of metal hoops, with long “wings” on either side of the opening to guide the platypus inside. The opposite end is staked up on the bank to ensure enough of the net remains above water for the animal to surface and breathe. Once caught, each animal is measured and weighed and — if it’s a first-time capture — marked before being released back into its home stream.
“They are probably the most difficult species I’ve ever worked on,” says Griffiths, who nevertheless has dedicated the past 12 years of his life to understanding them. One of Australia’s foremost platypus experts, he works with city water officials to study and monitor populations in waterways in and around Melbourne. “There’s a number of challenges with platypuses, and it’s one of the reasons we don’t have good data on them,” he says.
As difficult as it has been to study the basic biology of the platypus, it has been even harder to figure out just where all the populations are, and for those that are known, how those populations are faring. But several recent research initiatives are starting to fill those data gaps.
A recently completed three-year national survey by Kingsford, Griffiths and a dozen other researchers combined information from capture-and-release surveys, studies that used acoustic sensors to track platypus movements, environmental DNA data, and historical accounts to sketch out the species’ abundance and distribution, and determine where it’s at risk. The Australian Research Council-funded study, to be published later this month, found that the species is worse off than scientists expected and warns that if the threats that some platypus populations are up against are not dealt with swiftly, the species’ status will only deteriorate further. Using some of the same information, the IUCN downgraded the species’ status to Near Threatened in 2016. Despite this, the platypus has yet to be protected nationally under Australia’s Environment Protection and Biodiversity Conservation Act or at the state level—except in the state of South Australia, where the species is barely hanging on and is listed as endangered.
All of the evidence so far implicates humans in the platypus’s decline. A panoply of human detritus and structures, including dams, crayfish traps, and pollution have killed the animals, restricted their movements, degraded their habitat and reduced their prey. Some of the most beleaguered populations are those that lie downstream from dams or in areas where land clearing or livestock grazing has eliminated streamside vegetation, including the trees whose roots buttress platypus burrows. Invasive predators, such as feral cats, dogs, and red foxes frequently kill platypuses, particularly juvenile males that must venture out onto terra firma in search of new territories. And fishing nets and traps that allow platypuses to enter but not escape drown many animals each year.
Fortunately, research and conservation efforts in the state of Victoria offer hope for how humans can better co-exist with the platypus. One of the best-studied watersheds is that of the Yarra River, which wends through the heart of Melbourne. While a local newspaper reported platypus sightings in the river in the early-20th century, the animals haven’t been seen downtown since. But there are still several populations upstream and in some Yarra tributaries, and Griffiths has studied many of them, in collaboration with an unusual partner: the local water agency, Melbourne Water. Under the city’s Healthy Waters Strategy, officials conduct surveys for platypuses and minimize threats to them.
“Because of that, we’ve been able to generate some amazing data,” Griffiths says. A combination of capture surveys, environmental DNA analyses, and a citizen science program that calls on residents to report sightings using a mobile phone app called “Platypus Spot” has provided researchers with a more complete picture of the species’ status in the area. This information is helping water and wildlife managers determine where to focus conservation efforts, and where it’s particularly important to prevent further habitat degradation. The information that Griffiths and others have collected in recent years has also helped convince the state of Victoria to ban a particularly deadly type of trap known as an “opera house trap” (named for their resemblance to the Sydney Opera House).
Tiana Preston, who oversees Melbourne Water’s platypus conservation program, says that the agency is using these research findings to help reduce the many threats that platypuses face. For example, the agency knows now that storm runoff from parking lots and other paved surfaces can flood critical habitat and inundate platypus burrows. To help prevent this, Melbourne Water is working with developers and communities in the city—one of Australia’s fastest-growing — to educate them about the risks to platypuses and encourage them to install permeable pavement that allows rainwater soak into the ground instead, and to put in green roofs to capture rainfall.
This is just one of many fixes that Griffiths and other researchers say are needed across the platypus’s range. Replanting trees along streams, keeping livestock away from riverside habitat that’s still intact, restoring natural streamflows, cleaning up polluted waterways and imposing a nationwide ban on opera house traps are all measures that would help to protect platypuses, they say.
Despite the sobering news that recent research has brought, researchers and conservationists committed to protecting the species all emphasize that there’s still time to revive its ailing populations and make sure the healthy ones continue to thrive. And that would happen much sooner, they add, if policymakers took action now, rather than waiting for additional data. Griffiths, for one, says he’s seen enough to convince him that the platypus already qualifies for protection. “I’d bet my house on it,” he says.
What is beyond dispute is that the platypus, once so common that it was thought to be an indelible part of the Australian landscape, is now in need of help from its greatest threat: people. “I think we’ve seen beyond any shadow of a doubt that the platypus isn’t a species we can take for granted,” says Williams.
This story originally appeared in bioGraphic, an online magazine featuring beautiful and surprising stories about nature and sustainability.
We measure stuff all the time – how long, how heavy, how hot, and so on – because we need to for things such as trade, health and knowledge. But making sure our measurements compare apples with apples has been a challenge: how to know if my kilogram weight or meter length is the same as yours.
You won’t notice anything – you will not be heavier or lighter than yesterday – because the transition has been made to be seamless.
Just the definitions of the seven base units of the SI (Système International d’Unités, or the International System of Units) are now completely different from yesterday.
Humans have always been able to count, but as we evolved we quickly moved to measuring lengths, weights and time.
The Egyptian Pharaohs caused pyramids to be built based on the length of the royal forearm, known as the Royal Cubit. This was kept and promulgated by engineer priests who maintained the standard under pain of death.
But the cubit wasn’t a fixed unit over time – it was about half a meter, plus or minus a few tens of millimeters by today’s measure.
The first suggestion of a universal set of decimal measures was made by John Wilkins, in 1668, then Secretary of the Royal Society in London.
The impetus for doing something practical came with the French Revolution. It was the French who defined the first standards of length and mass, with two platinum standards representing the meter and the kilogram on June 22, 1799, in the Archives de la République in Paris.
Scientists backed the idea, the German mathematician Carl Friedrich Gauss being particularly keen. Representatives of 17 nations came together to create the International System of Units by signing the Metre Convention treaty on May 20, 1875.
France, whose street cred had taken a battering in the Franco-Prussian war and was not the scientific power it once was, offered a beaten-up chateau in the Forest of Saint-Cloud as an international home for the new system.
The Pavilion de Breteuil still houses the Bureau International de Poids et Mesures (BIPM), where resides the International Prototype of the Kilogram (henceforth the Big K) in two safes and three glass bell jars.
The Big K is a polished block of platinum-iridium used to define the kilogram, against which all kilogram weights are ultimately measured. (The original has only been weighed three times against a number of near-identical copies.)
The British, who had been prominent in the discussions and had provided the platinum-iridium kilogram, refused to sign the Treaty until 1884.
Even then the new system was only used by scientists, with everyday life being measured in traditional Imperial units such as pounds and ounces, feet and inches.
The United States signed the Treaty on the day, but then never actually implemented it, hanging on to its own version of the British Imperial system, which it still mostly uses today.
The US may have rued that decision in 1999, however, when the Mars Climate Orbiter (MCO) went missing in action. The report into the incident, quaintly called a “mishap” (which cost $193.1 million in 1999), said:
[…] the root cause for the loss of the MCO spacecraft was the failure to use metric units in the coding of a ground software file, “Small Forces”, used in trajectory models.
Essentially the spacecraft was lost in the atmosphere of Mars as it entered orbit lower than planned.
So why the change today? The main problems with the previous definitions were, in the case of the kilogram, they were not stable and, for the unit of electric current, the ampere, could not be realized.
And from weighings against official copies, we think the Big K was slowly losing mass.
All the units are now defined in a common way using what the BIPM calls the “explicit constant” formulation.
The idea is that we take a universal constant – for example, the speed of light in a vacuum – and from now on fix its numerical value at our best-measured value, without uncertainty.
Reality is fixed, the number is fixed, and so the units are now defined.
We therefore needed to find seven constants and make sure all measurements are consistent, within measurement uncertainty, and then start the countdown to today. (All the technical details are available here.)
Australia had a hand in fashioning the roundest macroscopic object on the Earth, a silicon sphere used to measure the Avogadro constant, the number of entities in a fixed amount of substance. This now defines the SI unit, mole, used largely in chemistry.
What of the Big K – the standard kilogram? Today it becomes an object of great historical significance that can be weighed and its mass will have measurement uncertainty.
From today the kilogram is defined using the Planck constant, something that doesn’t change from quantum physics.
The challenge now though is to explain these new definitions to people – especially non-scientists – so they understand. Comparing a kilogram to a metal block is easy.
Technically a kilogram (kg) is now defined:
[…] by taking the fixed numerical value of the Planck constant h to be 6.626 070 15 × 10–34 when expressed in the unit J s, which is equal to kg m2 s–1, where the metre and the second are defined in terms of c and ΔνCs.
Try explaining that to someone!
You probably already had a feeling you should skip the vending machine for an afternoon snack. But it turns out ultra-processed foods are even worse than we already thought.
A new study, out in Cell Metabolism, shows these foods cause weight gain even when they don’t have more fat, sugar, or carbohydrates than their healthier counterparts. There’s something about the processing itself that causes people to eat more before they feel full. On the flip side, switching to a whole food diet — even with no calorie restriction — can lead to measurable weight loss in just two weeks, the researchers found.
Claims like this crop up all the time, but it’s always been tricky to isolate the “processed-ness” of various foods from other factors that often go along with it. The foods have more salt, sugar and fat; less protein, less fiber; and the people who eat them most might also have lower socioeconomic status, higher stress or exercise less. But researchers wanted to get all that other stuff out of the way to look at whether processing foods alone made any difference. It was no small feat.
“These kinds of studies are very rare and the way that we did this really relies on our ability to have the facilities that we do,” says Kevin Hall, lead researcher on the study. He’s chief of the Integrative Physiology Section at the National Institute of Health (NIH).
To pull off the study, twenty volunteers checked themselves into an NIH facility. And they didn’t leave — for a whole month.
“If we allow people to leave, which we didn’t … we don’t know if they are sticking to the diets or not,” says Hall. “That’s a big problem in nutrition science in general.”
Only in the past decade or so have diet and nutrition researchers started talking about foods in terms of how processed they are. On the natural end of the spectrum, you’ve got foods like fruit and veggies, steaks and beans. Somewhere in the middle you’ve got things like roasted and salted nuts, canned tuna and most cheeses (these are, technically, “processed”). On the other end are the hot dogs and frozen heat-and-eat meals. These ultra-processed foods have five or more ingredients, often many more, and are made up of oils, preservatives and other substances that you wouldn’t find in your pantry.
These foods go through serious manufacturing between when the raw ingredients are picked, caught or slaughtered and when something resembling food reaches your taste buds. During that processing, whole foods are broken down into their component parts (like corn oil or whey protein concentrate or citric acid) and then re-constituted into something else (like Doritos).
During their month at the NIH’s Metabolic Clinical Research Unit, participants were given three meals a day, plus snacks. They spent the first two weeks on either a diet of entirely ultra-processed foods or a diet of entirely un-processed foods. Then they’d switch to the other and stay two more weeks.
The participants, 10 men and 10 women in their early thirties, each around 170-175 pounds, also got 60 minutes of low intensity exercise per day. As the days went on, researchers weighed the subjects and kept track of how many calories they ate at each meal.
The participants were always presented with precisely twice the amount of food they would need to maintain their weight — so they could always eat until they were full.
The researchers also measured a laundry list of other vital signs, like blood glucose levels, insulin resistance, energy expenditure, cholesterol … you name it.
The bulk of these vital signs remained unchanged regardless of which diet the participants were on. But at the end of two weeks eating only ultra-processed foods, everybody gained, on average, 2.5 pounds. They ate 500 more calories a day on the processed diet, the researchers found. And most of those extra calories came from fat and carbohydrates.
But after two weeks of unprocessed foods, everybody lost the same amount of weight on average, regardless of where they started: 2.5 pounds.
I hope you’re thinking: But ultra-processed foods have more fat and carbs than their health food counterparts!
The researchers thought of that. Both diets were completely balanced in terms of their nutrients: same amount of fat, same amount of carbs, same amount of protein. Even sugar, sodium and fiber were kept consistent.
“I certainly didn’t think we’d get as big of an effect size once we matched for the nutrients the way that we did, especially the salt and the sugar and the fat,” says Hall.
The participants were given the same amounts of everything, but could eat what they wanted on their plates. Although they ate more fats and carbs on the ultra-processed diet, they ate the same amount of protein on both.
But ultra-processed foods are delicious and healthy food is not, of course people eat more!
Well, the researchers thought of that, too. They didn’t want any problems arising from personal preferences or because someone’s never seen quinoa before. So the participants were all asked to rate their food on its tastiness and familiarity. The meals on the two diet plans came out equal for both.
“[Kevin Hall] gave us two gifts,” says Carlos Monteiro, not involved in this study, who has been studying ultra-processed foods for a decade. Monteiro is a professor of nutrition and public health at the University of Sao Paulo, Brazil.
“One [is] showing that there’s a causal relationship between ultra-processed foods and weight gain,” he says. “And the second one is that reformulation will not work.”
Reformulation, as Monteiro explains it, is the idea that producers can make their processed foods healthier by adjusting the proportions of nutrients. Lower the fats, carbs, sugars and salts in processed foods; raise the protein and fiber. But this study shows that won’t necessarily work — processed is still worse, all else held equal.
Figuring out why this is, though, will require more research. “We don’t know exactly what we are losing when we change from foods that we’ve made part of our diet for millions of years to these recombinations of macronutrients,” says Monteiro.
Hall and his team published the full menus from the study alongside their research article. Before I opened it, I was fairly confident of what would be in the ultra-processed meal plan: hot dogs, French fries, candy, maybe some Kool-Aid.
I was not prepared to see what I’d consider a fairly normal spread. A sandwich with lunch meat, baked potato chips and blueberry yogurt. A (canned) bean and cheese burrito on a tortilla with (jarred) salsa and sour cream. A bagel and cream cheese. Cheerios. I’m no expert on how the majority of Americans eat, but I’m willing to go out on a limb and say that this feels normal to me.
And eating this way, the people in the study gained 2.5 pounds in 2 weeks.
Then those same people switched from sweetened fruit yogurt to plain Greek. They ate way, way more fruits and vegetables and meats from the deli counter and all the nuts they wanted. Everything was fresh — they even switched their beans from canned to dried. They didn’t count calories. They didn’t restrict carbs. They didn’t eat vegan, or paleo or sugar free. And they lost 2.5 pounds in 2 weeks.
Now if you’ll excuse me, I need to buy some groceries.