After five years on Mars, the Curiosity rover is an old pro at doing science on the Red Planet. Since sticking its landing on August 5, 2012, NASA’s Little Robot That Could has learned a lot about its environs.

Its charge was simple: Look for signs that Gale crater, a huge impact basin with a mountain at its center, might once have been habitable (for microbes, not Matt Damon). Turning over rocks across the crater, the rover has compiled evidence of ancient water — a lake fed by rivers once occupied the crater itself — and organic compounds and other chemicals essential for life.
NASA has extended the mission through October 2018. And there’s still plenty of interesting chemistry and geology to be done. As the robot continues to climb Mount Sharp at the center of the crater, Curiosity will explore three new rock layers: one dominated by the iron mineral hematite, one dominated by clay and one with lots of sulfate salts.

So, here are four Martian mysteries that Curiosity could solve (or at least dig up some dirt on).

Does Mars harbor remnants of ancient life?
Curiosity’s Mars Hand Lens Imager can take microscopic images, but preserved cells or microfossils would still have to be pretty big for the camera to see them. What the rover can do is detect the building blocks for those cells with its portable chemistry lab, Sample Analysis at Mars. The lab has already picked up chlorobenzene, a small organic molecule with a carbon ring, in ancient mud rock. Chains of such molecules go into making things like cell walls and other structures.
“We’ve only found simple organic molecules so far,” says Ashwin Vasavada, a planetary scientist at NASA’s Jet Propulsion Laboratory who leads Curiosity’s science team. Detective work in chemistry labs here on Earth could shed light on whether bigger organic molecules on Mars’ surface might degrade into smaller ones like chlorobenzene.

Curiosity could still turn up intact, heavier-duty carbon chains. The rover carries two sets of cups to do chemistry experiments, one dry and one wet. The latter contains chemical agents designed to draw out hard-to-find organic compounds. None of the wet chemistry cups have yet been used. A problem with Curiosity’s drill in December 2016 has held up the search for organics, but possible solutions are in the works.
How did Mars go from warm and wet to cold and dry?
That’s one of the million-dollar questions about the Red Planet. Curiosity has piled on evidence that Mars was once a much more hospitable place. Around 3.5 billion years ago, things changed.

The going theory is that particles from the sun stripped away much of Mars’ atmosphere (and continues to do so) when the planet lost most of its protective magnetic field. “That caused the climate to change from one that could support water at the surface to the dry planet it is today,” Vasavada explains. Curiosity found a higher ratio of heavy elements in the current atmosphere, adding credence to this argument — presumably the lighter elements were the first to go.

There’s also a chance that as the rover hikes up Mount Sharp it could capture regional evidence of the wet-to-dry transition. So far, Curiosity has investigated rocks from the tail end of the wet period. The new geologic layers it will encounter are younger.

“Hopefully we’ll be able to get some insight by looking at these rocks into some of the global changes happening that maybe no longer permitted a lake to be present on the surface,” says Abigail Fraeman, a research scientist at NASA’s Jet Propulsion Lab.
Does Mars really have flowing water today?
Some mineralized salts absorb water and release it as liquid when they break down at certain temperatures. The Curiosity team looked for the bursts of water that might result from such a process in Gale crater and came up empty.

But in 2015, the Mars Reconnaissance Orbiter snapped images of shifting salt streaks indicative of actively flowing water. The images are the best evidence yet that liquid water might not be a thing of the past.

Mount Sharp has similar dark streaks, and Curiosity periodically takes pictures of them. “It’s something we keep an eye on,” Vasavada says. If the streaks change in a way that might indicate that they’re moving, the rover could corroborate evidence of modern-day water on Mars. But so far, the streaks have stayed stagnant.

Where does the methane in Mars’ atmosphere come from?
On Earth, microbes are big methane producers, but on Mars, methane’s origins are still unclear. Early on Curiosity detected extremely low levels of the gas in Mars’ atmosphere. This baseline appears to subtly fluctuate annually — perhaps driven by temperature or pressure. Curiosity continues to monitor methane levels, and more data and modeling could help pinpoint what’s behind the annual ups and downs.

At the end of 2014, researchers noticed a spike 10 times the baseline level. Scientists suspect that methane sticks around in the air on Mars for only about 300 years. So, the methane spike must be relatively new to the atmosphere. “That doesn’t necessarily mean it’s being actively created,” Vasavada says. “It could be old methane being released from underground.” Minerals interacting with subterranean water sometimes make methane gas.

Mars’ methane could also be the product of planetary dust particles broken down on the surface. And yet another possible explanation is biological activity. “We have zero information to know whether that’s happening on Mars, but we shouldn’t exclude it as an idea,” says Vasavada. So, Martian life is unlikely but can’t be completely ruled out.

If you look at a map of the world, it’s easy to think that the vast oceans would be effective barriers to the movement of land animals. And while an elephant can’t swim across the Pacific, it turns out that plenty of plants and animals — and even people — have unintentionally floated across oceans from one continent to another. Now comes evidence that tiny, sedentary trapdoor spiders made such a journey millions of years ago, taking them from Africa all the way across the Indian Ocean to Australia.

Moggridgea rainbowi spiders from Kangaroo Island, off the south coast of Australia, are known as trapdoor spiders because they build a silk-lined burrow in the ground with a secure-fitting lid, notes Sophie Harrison of the University of Adelaide in Australia. The burrow and trapdoor provides the spiders with shelter and protection as well as a means for capturing prey. And it means that the spiders don’t really need to travel farther than a few meters over the course of a lifetime.

There was evidence, though, that the ancestors of these Australian spiders might have traveled millions of meters to get to Australia — from Africa. That isn’t as odd as it might seem, since Australia used to be connected to other continents long ago in the supercontinent Gondwana. And humans have been known to transport species all over the planet. But there’s a third option, too: The spiders might have floated their way across an ocean.

To figure out which story is most likely true, Harrison and her colleagues looked at the spider’s genes. They turned to six genes that have been well-studied by spider biologists seeking to understand relationships between species. The researchers looked at those genes in seven M. rainbowi specimens from Kangaroo Island, five species of Moggridgea spiders from South Africa and seven species of southwestern Australia spiders from the closely related genus Bertmainius.

Using that data, the researchers built a spider family tree that showed which species were most closely related and how long ago their most recent common ancestor lived. M. rainbowi was most closely related to the African Moggridgea spiders, the analysis revealed. And the species split off some 2 million to 16 million years ago, Harrison and her colleagues report August 2 in PLOS ONE.

The timing of the divergence was long after Gondwana split up. And it was long before either the ancestors of Australia’s aboriginal people or later Europeans showed up on the Australian continent. While it may be improbable that a colony of spiders survived a journey of 10,000 kilometers across the Indian Ocean, that is the most likely explanation for how the trapdoor spiders got to Kangaroo Island, the researchers conclude.

Such an ocean journey would not be unprecedented for spiders in this genus, Harrison and her colleagues note. There are three species of Moggridgea spiders that are known to live on islands off the shore of the African continent. Two live on islands that were once part of the mainland, and they may have diverged at the same time that their islands separated from Africa. But the third, M. nesiota, lives on the Comoros, which are volcanic islands. The spiders must have traveled across 340 kilometers of ocean to get there.
These types of spiders may be well-suited to ocean travel. If a large swatch of land washes into the sea, laden with arachnids, the spiders may be able to hide out in their nests for the journey. Plus, they don’t need a lot of food, can resist drowning and even “hold their breath” and survive on stored oxygen during periods of temporary flooding, the researchers note.

Plate tectonics may have gotten a pretty early start in Earth’s history. Most estimates put the onset of when the large plates that make up the planet’s outer crust began shifting at around 3 billion years ago. But a new study in the Sept. 22 Science that analyzes titanium in continental rocks asserts that plate tectonics began 500 million years earlier.

Nicolas Greber, now at the University of Geneva, and colleagues suggest that previous studies got it wrong because researchers relied on chemical analyses of silicon dioxide in shales, sedimentary rocks that bear the detritus of a variety of continental rocks. These rocks’ silicon dioxide composition can give researchers an idea of when continental rocks began to diverge in makeup from oceanic rocks as a result of plate tectonics.

But weathering can wreak havoc on the chemical makeup of shales. To get around that problem, Greber’s team turned to a new tool: the ratios of two titanium isotopes, forms of the same element that have different masses. The proportion of titanium isotopes in the rocks is a useful stand-in for the difference in silicon dioxide concentration between continental and oceanic rocks, and isn’t so easily altered by weathering. Those data helped the team estimate that continental rocks — and therefore plate tectonics — were already going strong by 3.5 billion years ago.

When you think about it, it shouldn’t be surprising that there’s more than one way to explain quantum mechanics. Quantum math is notorious for incorporating multiple possibilities for the outcomes of measurements. So you shouldn’t expect physicists to stick to only one explanation for what that math means. And in fact, sometimes it seems like researchers have proposed more “interpretations” of this math than Katy Perry has followers on Twitter.

So it would seem that the world needs more quantum interpretations like it needs more Category 5 hurricanes. But until some single interpretation comes along that makes everybody happy (and that’s about as likely as the Cleveland Browns winning the Super Bowl), yet more interpretations will emerge. One of the latest appeared recently (September 13) online at arXiv.org, the site where physicists send their papers to ripen before actual publication. You might say papers on the arXiv are like “potential publications,” which someday might become “actual” if a journal prints them.

And that, in a nutshell, is pretty much the same as the logic underlying the new interpretation of quantum physics. In the new paper, three scientists argue that including “potential” things on the list of “real” things can avoid the counterintuitive conundrums that quantum physics poses. It is perhaps less of a full-blown interpretation than a new philosophical framework for contemplating those quantum mysteries. At its root, the new idea holds that the common conception of “reality” is too limited. By expanding the definition of reality, the quantum’s mysteries disappear. In particular, “real” should not be restricted to “actual” objects or events in spacetime. Reality ought also be assigned to certain possibilities, or “potential” realities, that have not yet become “actual.” These potential realities do not exist in spacetime, but nevertheless are “ontological” — that is, real components of existence.

“This new ontological picture requires that we expand our concept of ‘what is real’ to include an extraspatiotemporal domain of quantum possibility,” write Ruth Kastner, Stuart Kauffman and Michael Epperson.

Considering potential things to be real is not exactly a new idea, as it was a central aspect of the philosophy of Aristotle, 24 centuries ago. An acorn has the potential to become a tree; a tree has the potential to become a wooden table. Even applying this idea to quantum physics isn’t new. Werner Heisenberg, the quantum pioneer famous for his uncertainty principle, considered his quantum math to describe potential outcomes of measurements of which one would become the actual result. The quantum concept of a “probability wave,” describing the likelihood of different possible outcomes of a measurement, was a quantitative version of Aristotle’s potential, Heisenberg wrote in his well-known 1958 book Physics and Philosophy. “It introduced something standing in the middle between the idea of an event and the actual event, a strange kind of physical reality just in the middle between possibility and reality.”

In their paper, titled “Taking Heisenberg’s Potentia Seriously,” Kastner and colleagues elaborate on this idea, drawing a parallel to the philosophy of René Descartes. Descartes, in the 17th century, proposed a strict division between material and mental “substance.” Material stuff (res extensa, or extended things) existed entirely independently of mental reality (res cogitans, things that think) except in the brain’s pineal gland. There res cogitans could influence the body. Modern science has, of course, rejected res cogitans: The material world is all that reality requires. Mental activity is the outcome of material processes, such as electrical impulses and biochemical interactions.

Kastner and colleagues also reject Descartes’ res cogitans. But they think reality should not be restricted to res extensa; rather it should be complemented by “res potentia” — in particular, quantum res potentia, not just any old list of possibilities. Quantum potentia can be quantitatively defined; a quantum measurement will, with certainty, always produce one of the possibilities it describes. In the large-scale world, all sorts of possibilities can be imagined (Browns win Super Bowl, Indians win 22 straight games) which may or may not ever come to pass.

If quantum potentia are in some sense real, Kastner and colleagues say, then the mysterious weirdness of quantum mechanics becomes instantly explicable. You just have to realize that changes in actual things reset the list of potential things.

Consider for instance that you and I agree to meet for lunch next Tuesday at the Mad Hatter restaurant (Kastner and colleagues use the example of a coffee shop, but I don’t like coffee). But then on Monday, a tornado blasts the Mad Hatter to Wonderland. Meeting there is no longer on the list of res potentia; it’s no longer possible for lunch there to become an actuality. In other words, even though an actuality can’t alter a distant actuality, it can change distant potential. We could have been a thousand miles away, yet the tornado changed our possibilities for places to eat.

It’s an example of how the list of potentia can change without the spooky action at a distance that Einstein alleged about quantum entanglement. Measurements on entangled particles, such as two photons, seem baffling. You can set up an experiment so that before a measurement is made, either photon could be spinning clockwise or counterclockwise. Once one is measured, though (and found to be, say, clockwise), you know the other will have the opposite spin (counterclockwise), no matter how far away it is. But no secret signal is (or could possibly be) sent from one photon to the other after the first measurement. It’s simply the case that counterclockwise is no longer on the list of res potentia for the second photon. An “actuality” (the first measurement) changes the list of potentia that still exist in the universe. Potentia encompass the list of things that may become actual; what becomes actual then changes what’s on the list of potentia.

Similar arguments apply to other quantum mysteries. Observations of a “pure” quantum state, containing many possibilities, turns one of those possibilities into an actual one. And the new actual event constrains the list of future possibilities, without any need for physical causation. “We simply allow that actual events can instantaneously and acausally affect what is next possible … which, in turn, influences what can next become actual, and so on,” Kastner and colleagues write.

Measurement, they say, is simply a real physical process that transforms quantum potentia into elements of res extensa — actual, real stuff in the ordinary sense. Space and time, or spacetime, is something that “emerges from a quantum substratum,” as actual stuff crystalizes out “of a more fluid domain of possibles.” Spacetime, therefore, is not all there is to reality.

It’s unlikely that physicists everywhere will instantly cease debating quantum mysteries and start driving cars with “res potentia!” bumper stickers. But whether this new proposal triumphs in the quantum debates or not, it raises a key point in the scientific quest to understand reality. Reality is not necessarily what humans think it is or would like it to be. Many quantum interpretations have been motivated by a desire to return to Newtonian determinism, for instance, where cause and effect is mechanical and predictable, like a clock’s tick preceding each tock.

But the universe is not required to conform to Newtonian nostalgia. And more generally, scientists often presume that the phenomena nature offers to human senses reflect all there is to reality. “It is difficult for us to imagine or conceptualize any other categories of reality beyond the level of actual — i.e., what is immediately available to us in perceptual terms,” Kastner and colleagues note. Yet quantum physics hints at a deeper foundation underlying the reality of phenomena — in other words, that “ontology” encompasses more than just events and objects in spacetime.
This proposition sounds a little bit like advocating for the existence of ghosts. But it is actually more of an acknowledgment that things may seem ghostlike only because reality has been improperly conceived in the first place. Kastner and colleagues point out that the motions of the planets in the sky baffled ancient philosophers because supposedly in the heavens, reality permitted only uniform circular motion (accomplished by attachment to huge crystalline spheres). Expanding the boundaries of reality allowed those motions to be explained naturally.

Similarly, restricting reality to events in spacetime may turn out to be like restricting the heavens to rotating spheres. Spacetime itself, many physicists are convinced, is not a primary element of reality but a structure that emerges from processes more fundamental. Because these processes appear to be quantum in nature, it makes sense to suspect that something more than just spacetime events has a role to play in explaining quantum physics.

True, it’s hard to imagine the “reality” of something that doesn’t exist “actually” as an object or event in spacetime. But Kastner and colleagues cite the warning issued by the late philosopher Ernan McMullin, who pointed out that “imaginability must not be made the test for ontology.” Science attempts to discover the real world’s structures; it’s unwarranted, McMullin said, to require that those structures be “imaginable in the categories” known from large-scale ordinary experience. Sometimes things not imaginable do, after all, turn out to be real. No fan of the team ever imagined the Indians would win 22 games in a row.

How do you observe the invisible currents of the atmosphere? By studying the swirling, billowing loads of sand, sea salt and smoke that winds carry. A new simulation created by scientists at NASA’s Goddard Space Flight Center in Greenbelt, Md., reveals just how far around the globe such aerosol particles can fly on the wind.

The complex new simulation, powered by supercomputers, uses advanced physics and a state-of-the-art climate algorithm known as FV3 to represent in high resolution the physical interactions of aerosols with storms or other weather patterns on a global scale (SN Online: 9/21/17). Using data collected from NASA’s Earth-observing satellites, the simulation tracked how air currents swept aerosols around the planet from August 1, 2017, through November 1, 2017.
In the animation, sea salt (in blue) snagged by winds sweeping across the ocean’s surface becomes entrained in hurricanes Harvey, Irma, Jose and Maria, revealing their deadly paths. Wisps of smoke (in gray) from fires in the U.S. Pacific Northwest drift toward the eastern United States, while Saharan dust (in brown) billows westward across the Atlantic Ocean to the Gulf of Mexico. And the visualization shows how Hurricane Ophelia formed off the coast of Africa, pulling in both Saharan dust and smoke from Portugal’s wildfires and transporting the particles to Ireland and the United Kingdom.

Warming waters are turning some sea turtle populations female — to the extreme. More than 99 percent of young green turtles born on beaches along the northern Great Barrier Reef are female, researchers report January 8 in Current Biology. If that imbalance in sex continues, the overall population could shrink.

Green sea turtle embryos develop as male or female depending on the temperature at which they incubate in sand. Scientists have known that warming ocean waters are skewing sea turtle populations toward having more females, but quantifying the imbalance has been hard.
Researchers analyzed hormone levels in turtles collected on the Great Barrier Reef (off the northeastern coast of Australia) to determine their sex, and then used genetic data to link individuals to the beaches where the animals originated. That two-pronged approach allowed the scientists to estimate the ratio of males to females born at different sites.

The sex ratio in the overall population is “nothing out of the ordinary,” with roughly one juvenile male for every four juvenile females, says study coauthor Michael Jensen, a marine biologist with the National Oceanic and Atmospheric Administration in La Jolla, Calif. But breaking the data down by the turtles’ region of origin revealed worrisome results. In the cooler southern Great Barrier Reef, 67 percent of hatched juveniles were female. But more than 99 percent of young turtles hatched in sand soaked by warmer waters in the northern Great Barrier Reef were female — with one male for every 116 females. That imbalance has increased over time: 86 percent of the adults born in the area more than 20 years ago were female.

It’s unclear what the long-term impact of such a strong skew will be, but it’s probably not good news for the turtles. Sea turtle populations can get by with fewer males than females (SN: 3/4/17, p. 16), but scientists aren’t sure how many is too few. And while turtles can adapt their behavior, such as laying eggs in cooler places, the animals’ instinct is to nest in the same spot they were born, which works against such a change.

Orlando Brown Jr.'s first order of business as a member of the Bengals? Partner with Cincinnati's mayor in a humorous trailer for the team's Week 17 clash vs. Brown's old squad, the Chiefs.

Brown showed off his acting chops alongside the head of his new hometown.

Check it out here:
The full NFL 2023 schedule will be announced Thursday, May 11.

Pureval famously got into a war of words with Kansas City stars Patrick Mahomes and Travis Kelce when the two sides battled in January for a berth in the Super Bowl. It seemed his words helped to light a fire under KC; Mahomes threw for three touchdowns as the Chiefs sent the Bengals home and marched toward another Super Bowl triumph.

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Back then, Brown was protecting Mahomes' blind side. He switched sides during the offseason, signing a four-year, $64 million deal with Cincinnati to keep rushers from putting Joe Burrow on his back. As such, his loyalties have changed, and in a show of goodwill, he offered Pureval some advice.

"Yeah, I think that was better than last time," Brown said after recording Pureval's vanilla reveal of the New Year's Eve game scheduled to be played in Kansas City. The mayor was far less fiery than when he declared Arrowhead Stadium "Burrowhead" ahead of the AFC championship game.

MORE: Best games on 2023 NFL schedule by team

Suffice to say, Mahomes and Kelce got the last laugh then. Not only did they vanquish their AFC rivals, they also were loud about it, hopping on the microphone to dish dirt.

"Know your role and shut your mouth, you jabroni," Kelce said, mimicking The Rock.

MORE: Ranking all 16 AFC QBs as Aaron Rodgers joins loaded conference

Revenge is a dish best served cold. But it's always nice to see someone laugh at themselves after getting caught with their foot in their mouth. Brown's cameo should add intrigue to what is certain to be one of the most-watched games of the 2023 regular season.

Zeptonewton
ZEP-toe-new-ton n.
A unit of force equal to one billionth of a trillionth of a newton.

An itty-bitty object can be used to suss out teeny-weeny forces.

Scientists used an atom of the element ytterbium to sense an electromagnetic force smaller than 100 zeptonewtons, researchers report online March 23 in Science Advances. That’s less than 0.0000000000000000001 newtons — with, count ‘em, 18 zeroes after the decimal. At about the same strength as the gravitational pull between a person in Dallas and another in Washington, D.C., that’s downright feeble.
After removing one of the atom’s electrons, researchers trapped the atom using electric fields and cooled it to less than a thousandth of a degree above absolute zero (–273.15° Celsius) by hitting it with laser light. That light, counterintuitively, can cause an atom to chill out. The laser also makes the atom glow, and scientists focused that light into an image with a miniature Fresnel lens, a segmented lens like those used to focus lighthouse beams.

Monitoring the motion of the atom’s image allowed the researchers to study how the atom responded to electric fields, and to measure the minuscule force caused by particles of light scattering off the atom, a measly 95 zeptonewtons.