Blood is complicated: it changes texture, color and thickness depending on where it's flowing from and how fast. Though you can make a convincing fake blood with water, food coloring, flour and corn syrup, getting the proportions right depends on a scientific understanding of the context in which your fake blood is appearing. Read the rest

A new molecular study shows that a compound called perrotetinene in certain species of liverworts is actually a psychoactive cannabanoid. From Science News:

A group of Japanese scientists in 1994 discovered perrotetinene in liverworts, but the new study is the strongest evidence yet that the compound is a psychoactive cannabinoid. Previously, cannabis was the only plant known to produce such cannabinoids....

After mapping perrotetinene’s molecular structure, the researchers created a synthetic version and tested it on mice. The team tracked the animals’ pain response, body temperature and movement — measures of the compound’s psychoactivity. The results suggested that perrotetinene may be slightly less psychoactive than THC, says study coauthor Jürg Gertsch, a biochemist at the University of Bern in Switzerland. The liverwort compound may also have fewer negative side effects such as memory loss and loss of coordination, he says.

"Uncovering the psychoactivity of a cannabinoid from liverworts associated with a legal high" (Science Advances)

illustration: "Hepaticae" from Ernst Haeckel's Kunstformen der Natur, 1904 Read the rest

University of Cape Town researchers created the world's first "bio-bricks" made from sand, bacteria, and human urine collected from special toilets in the engineering school's bathrooms. From The Guardian:

Bio-bricks are created through a natural process called microbial carbonate precipitation, said (project supervisor and water quality engineering lecturer Dyllon) Randall, similar to the way seashells are formed. Loose sand, which has been colonised with bacteria that produces urease, is mixed with the urine. Urease breaks down the urea in the urine, producing calcium carbonate, which cements the sand into shape.

While regular bricks are kiln-fired at temperatures of 1,400C and produce large amounts of carbon dioxide, the bio-bricks do not require heat.

“If a client wanted a brick stronger than a 40% limestone brick, you would allow the bacteria to make the solid stronger by ‘growing’ it for longer,” said Randall...

Randall described urine as liquid gold. By volume, urine accounts for less than 1% of domestic waste water, but it contains 80% of the nitrogen, 56% of the phosphorus and 63% of the potassium found in waste water.

(via NextDraft) Read the rest

Microplastics -- the tiny pieces of plastic debris littering our planet -- has been found in human poop, surprising nobody. The pilot study included 8 people from seven countries in Europe plus Japan. While the study was obviously very small, the researchers did discover waste plastic such as that from food wrappers and synthetic clothing in feces from all the participants. According to lead researcher Dr. Philipp Schwabl of the University of Vienna, the study was too small to draw any huge conclusions but it does confirm what sadly was inevitable. From Laura Parker's feature in National Geographic:

“I’d say microplastics in poop are not surprising,” says Chelsea Rochman, an ecologist at the University of Toronto, who studies the effects of microplastics on fish. “For me, it shows we are eating our waste—mismanagement has come back to us on our dinner plates. And yes, we need to study how it may affect humans.”

Every year, an average of eight million tons of plastic waste, most of it single-use varieties, flows into the world’s oceans from coastal regions. There, sunlight and wave action break these waterborne plastics down into bits the size of grains of rice. Fibers from synthetic clothes such as polyester and acrylic make their way into freshwater systems via washing machines. You can see this in action with a fleece jacket; just scratching the arm of the jacket can shed invisible fibers. As a result, tiny plastic fragments and fibers have now spread all over the planet. They're in deep sea trenches and in the air we breathe.

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My name is Kelsey Juliana and I’m suing the United States government for causing and accelerating the climate change crisis. I’m 22 years old and I’ve been a climate advocate for more than half of my life. Read the rest

Kevin M. Gill, a software engineer and data wrangler at NASA-JPL, created the fantastic video below "using still images taken by the Cassini spacecraft during it's flyby of Jupiter and while at Saturn.

"Shown is Io and Europa over Jupiter's Great Red Spot and then Titan as it passes over Saturn and it's edge-on rings," Gill wrote on Flickr.

People seemed to like the Europa/Io/Titan gifs, so as an experiment I went and made a short video of them. The Voyage of the Moons.Image data via @CassiniSaturn https://t.co/8SLjERSRWc pic.twitter.com/kvznw9ck6J

— Kevin M. Gill (@kevinmgill) October 22, 2018

image credit: NASA/JPL-Caltech/SSI/CICLOPS/Kevin M. Gill Read the rest

When wind blows over the snow of Antarctica's Ross Ice Shelf, the surface vibrates and produces a beautiful and eery drone. Colorado State University researchers deployed seismometers to explore the subsurface of the ice shelf and were surprised to learn that their sensors recorded the natural song of the terrain. The frequencies are below the threshold of human hearing and are sped up for audibility in the video above. From the scientific paper:

Ice shelves are the floating buttresses of large glaciers that extend over the oceans and play a key role in restraining inland glaciers as they flow to the sea. Deploying sensitive seismographs across Earth’s largest ice shelf (the Ross Ice Shelf) for 2 years, we discovered that the shelf nearly continuously sings at frequencies of five or more cycles per second, excited by local and regional winds blowing across its snow dune-like topography. We find that the frequencies and other features of this singing change, both as storms alter the snow dunes and during a (January 2016) warming event that resulted in melting in the ice shelf’s near surface. These observations demonstrate that seismological monitoring can be used to continually monitor the near-surface conditions of an ice shelf and other icy bodies to depths of several meters.

More at Colorado State University News.

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Stephen Hawking's final book, Brief Answers to the Big Questions, was released posthumously Tuesday by his children. Read the rest

According to the explanation of the phrase "like a moth to the flame" at The Phrase Finder, "the word moth was used the the 17th century to mean someone who was apt to be tempted by something that would lead to their downfall." But why do moths have this fatal attraction anyway? National Geographic explains in the above video:

The theory is that these primarily nocturnal insects have evolved to travel by the light of the moon and stars. This way of travel is called transverse orientation. An easy way to think about transverse orientation is to imagine a sailor travelling in the direction of the North Star. In theory, moths similarly follow the light source at a precise position and a precise angle to their bodies. This is how moths would navigate for millions of years … by the light of the moon. What moth evolution couldn’t account for was the proliferation of constant electric light in our modern world. When Thomas Edison patented the lightbulb on January 27, 1880 it was a bad day in moth history. These lightbulbs began to act as artificial moons, confusing moths and overwhelming their senses. Since moths are accustomed to orienting to distant light sources, they can be easily disoriented when a closer light source, like a porch lamp, comes into view.

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Avogadro's Number is 6.022140857 × 10²³. That's how many atoms are in 12 grams of carbon-12. One mole of anything has one Avogadro's Number of elementary particles in it. In this video, the Action Lab Man repeats the words "Avogadro's Number," quadrupling the audio track each time until he reaches 6.022140857 × 10²³. Each time he utters the words, he includes an interesting fact about the in-progress number. For example 256 is the "Unplayable/unbeatable level in Pac-Man due to an 8-bit integer overflow." And 68,719,476,736 is the "Number of animals eaten by humans each year."

He ends the video by describing what would happen if you gathered together a mole of moles, as found in Randall Munroe's great book, What If? Serious Scientific Answers to Absurd Hypothetical Questions. Read the rest

Stephen Hawking's final paper that he and his colleagues completed just days before his death has now been published. It's titled "Black Hole Entropy and Soft Hair," co-authored with Sasha Haco, Malcolm J. Perry, and Andrew Strominger, about the black hole information paradox. Here is the abstract:

A set of infinitesimal VirasoroL⊗VirasoroR diffeomorphisms are presented which act non-trivially on the horizon of a generic Kerr black hole with spin J. The covariant phase space formalism provides a formula for the Virasoro charges as surface integrals on the horizon. Integrability and associativity of the charge algebra are shown to require the inclusion of `Wald-Zoupas' counterterms. A counterterm satisfying the known consistency requirement is constructed and yields central charges cL=cR=12J. Assuming the existence of a quantum Hilbert space on which these charges generate the symmetries, as well as the applicability of the Cardy formula, the central charges reproduce the macroscopic area-entropy law for generic Kerr black holes.

The Guardian has a translation:

In the latest paper, Hawking and his colleagues show how some information (contained in an object that falls into a black hole) at least may be preserved. Toss an object into a black hole and the black hole’s temperature ought to change. So too will a property called entropy, a measure of an object’s internal disorder, which rises the hotter it gets.

The physicists, including Sasha Haco at Cambridge and Andrew Strominger at Harvard, show that a black hole’s entropy may be recorded by photons that surround the black hole’s event horizon, the point at which light cannot escape the intense gravitational pull.

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Caltech researchers developed the illusion above to illustrate postdiction, a sensory phenomenon "in which a stimulus that occurs later can retroactively affect our perceptions of an earlier event." From Caltech Matters:

"Illusions are a really interesting window into the brain," says first author Noelle Stiles (PhD '15), a visitor in biology and biological engineering and a postdoctoral scholar–research associate at USC. "By investigating illusions, we can study the brain's decision-making process. For example, how does the brain determine reality with information from multiple senses that is at times noisy and conflicting? The brain uses assumptions about the environment to solve this problem. When these assumptions happen to be wrong, illusions can occur as the brain tries to make the best sense of a confusing situation. We can use these illusions to unveil the underlying inferences that the brain makes...."

Postdictive processing has been demonstrated within individual senses, but this work focuses on how the phenomenon can bridge multiple senses. The key to both of the new illusions is that the audio and visual stimuli occur rapidly, in under 200 milliseconds (one-fifth of a second). The brain, trying to make sense of this barrage of information, synthesizes the stimuli from both senses to determine the experience, using postdiction to do so.

Read more in the researchers' scientific paper: "What you saw is what you will hear: Two new illusions with audiovisual postdictive effects" (PLoS ONE) Read the rest

Gone, obviously. Tom Scocca:

Using our advanced technology, it is possible to look up the beaches in the National Oceanic and Atmospheric Administration’s Sea Level Rise Viewer, and to imagine what will happen if we visit them, or try to visit them, in the future—when the sea levels have risen three feet, or six feet, or more, if you want. You can use your pocket phone-computer to watch them move ahead through time below.

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Jupiter's frozen moon Europa has a massive ocean below the surface that could potentially harbor life. To find out, NASA is in the early stages of building a robotic lander to explore the moon in the mid-2020s. Now though, Cardiff University researcher Daniel Hobley and colleagues suggest that touching down on Europa could be tricky due to fields of massive ice spikes jutting up as high as 50 feet. From Science:

Such spikes are created on Earth in the frigid tropical peaks of the Andes Mountains, where they are called “penitentes,” for their resemblance to devout white-clad monks. First described by Charles Darwin, penitentes are sculpted by the sun in frozen regions that experience no melt; instead, the fixed patterns of light cause the ice to directly vaporize, amplifying minute surface variations that result in small hills and shadowed hollows. These dark hollows absorb more sunlight than the bright peaks around them, vaporizing down further in a feedback loop.

From the research paper in the scientific journal Nature:

We estimate that penitentes on Europa could reach 15 m in depth with a spacing of 7.5 m near the equator, on average, if they were to have developed across the interval permitted by Europa’s mean surface age. Although available images of Europa have insufficient resolution to detect surface roughness at the multi-metre scale, radar and thermal data are consistent with our interpretation. We suggest that penitentes could pose a hazard to a future lander on Europa.

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Very quickly. Before it, and you, freeze.

On Cyprien Verseux's Twitter account, wonderful snapshots of fun with food on the bleak, frozen ice sheets of Antarctica. Read the rest

NASA's Voyager 2 space probe, launched in 1977 on a grand tour of the solar system, may be nearing interstellar space. Carrying a message for extraterrestrials, the iconic Golden Record, the Voyager 2 is now about 11 billion miles (about 17.7 billion kilometers) from Earth and still sends data back daily from its various sensors. Most recently, it has detected an increase in higher-energy cosmic rays that originate outside our solar system. This increase in the rate of cosmic rays indicates that the Voyager 2 may soon break through the heliosphere, the "bubble" of charged particles generated by our sun, and cross into interstellar space. Voyager 1 entered interstellar space in 2012.

From the Jet Propulsion Laboratory:

The fact that Voyager 2 may be approaching the heliopause six years after Voyager 1 is also relevant, because the heliopause moves inward and outward during the Sun's 11-year activity cycle. Solar activity refers to emissions from the Sun, including solar flares and eruptions of material called coronal mass ejections. During the 11-year solar cycle, the Sun reaches both a maximum and a minimum level of activity.

"We're seeing a change in the environment around Voyager 2, there's no doubt about that," said Voyager Project Scientist Ed Stone, based at Caltech in Pasadena. "We're going to learn a lot in the coming months, but we still don't know when we'll reach the heliopause. We're not there yet -- that's one thing I can say with confidence."

In a decade or so, Voyager 1 and 2 will run out of power and go silent. Read the rest

The UN's International Panel on Climate Change is an interdisciplinary expert body comprised of leading scientists who study climate change; they issue periodic reports summarizing the best peer-reviewed science on climate change and making recommendations as to what must be done to avert the most catastrophic outcomes; their latest report is the gravest yet, where even the most optimistic projections of the panel predict disruption and hardship for tens of millions of people, within our lifetimes. Read the rest