Amazing Science

The mathematician-physicist Miranda Cheng is working on harnessing a mysterious connection between string theory, algebra and number theory.

A moonshine relates representations of a finite symmetry group to a function with special symmetries, ways that you can transform the function without affecting its output. Underlying this relationship, at least in the case of monstrous moonshine, is a string theory. String theory has two geometries. One is the “worldsheet” geometry. If you have a string — essentially a circle — moving in time, then you get a cylinder. That’s what we call the worldsheet geometry; it’s the geometry of the string itself. If you roll the cylinder and connect the two ends, you get a torus. The torus gives you the symmetry of the j-function. The other geometry in string theory is space-time itself, and its symmetry gives you the monster group.

Scientists are baffled at this seemingly altruistic behavior, which seems to be a concerted global effort to foil killer whale hunts.

Humans might not be the only creatures that care about the welfare of other animals. Scientists are beginning to recognize a pattern in humpback whale behavior around the world, a seemingly intentional effort to rescue animals that are being hunted by killer whales.

Marine ecologist Robert Pitman observed a particularly dramatic example of this behavior back in 2009, while observing a pod of killer whales hunting a Weddell seal trapped on an ice floe off Antarctica. The orcas were able to successfully knock the seal off the ice, and just as they were closing in for the kill, a magnificent humpback whale suddenly rose up out of the water beneath the seal.

This was no mere accident. In order to better protect the seal, the whale placed it safely on its upturned belly to keep it out of the water. As the seal slipped down the whale's side, the humpback appeared to use its flippers to carefully help the seal back aboard. Finally, when the coast was clear, the seal was able to safely swim off to another, more secure ice floe.

Aliens Or Not? In September 2015, astronomers and citizen scientists published a paper describing a “bizarre” transit signal recorded by Kepler, outlining a few possible causes for the phenomenon around KIC 8462852 — informally known as “Tabby’s Star.” On 2 occasions during Kepler’s prime observing run, huge transits were detected around the star.

Usually, Kepler will detect periodic dips in star brightness and the amount of dimming relates to the size of the exoplanet passing in front of the star. Typically, for a small exoplanet, this dip in brightness is of the order of a couple of percent. But the two transit signals detected around Tabby’s Star were dramatic.

The first transit dipped by 15 percent, but the second transit (that consisted of several objects passing in front of the star over several weeks) dipped to as much as 22 percent. The strength of the transit and its multi-object nature was unprecedented.

Many natural phenomena were explored and the researchers eventually focused on the possibility of a swarm of comets as being the most likely culprit. A nearby star, they argued, may have destabilized comets in Tabby’s Star’s Oort cloud (a hypothetical region surrounding a star containing countless billions of icy bodies), nudging a huge number of comets toward the star, blocking its light from view.

This explanation certainly fits many of the transit’s characteristics, but during an interview with The Atlantic, astronomer Jason Wright, an astronomer from Penn State University, discussed an alternate avenue of study that he wanted to investigate. On many occasions since, Wright and other astronomers have cautioned against jumping to the alien conclusion — after all, there are other, more likely natural explanations — but when faced with an unprecedented transit signal, why not explore the most extreme possibilities?

As with any speculation about aliens, the slim possibility of this Kepler signal being artificial caused an eruption of interest. While many scientists vented frustration at the frenzy of interest surrounding an unlikely scenario, whether they liked it or not, suddenly everyone was interested in Kepler science and hypotheses of an advanced alien civilization living in our galaxy. In my personal view, so long as the discussion remained planted firmly in the science, and not conspiracy theories and nonsense, this was no bad thing — especially as professional scientists were planning on investigating the possibility themselves.

So, if not comets, what could be causing the bizarre transit signal? Taking the age of our galaxy into consideration, it’s not such a stretch to think that if life is common in the Milky Way, perhaps there’s a vastly more advanced civilization to our own out there that has the ability to build huge solar energy collectors, say, around their host star. This speculation would certainly fit a Type II Kardashev civilization that has the ability to build huge megastructures around a star (much like a Dyson Sphere) to collect huge quantities of energy. Perhaps Kepler’s transit signal was several vast solar collectors passing in front of the star?

While it’s fun to think up all the possible structures an intelligent alien race might build, seeing a star dim a couple of times is hardly proof that aliens are out there. It’s not even evidence, especially when Occam’s Razor reminds us that there are other explanations out there with far fewer assumptions (i.e. the exocomet explanation). But in the interest of using Tabby’s Star as a point of scientific interest and respond to the huge public interest in the star, SETI Institute scientists turned to the their Allen Telescope Array (ATA) to “listen in” on the location.

The ATA is located a few hundred miles north of San Francisco, Calif., in the Cascade Mountains, consisting of 42 6-meter diameter radio antennae. The ATA was aimed at Tabby’s Star for 2 weeks and listened out for 2 specific radio signals. The first signal, of a narrow-band 1 Hz bandwidth, might be used as a “hailing signal”, according to the SETI Institute, for advanced alien civilizations to announce their presence. The second signal may be of a more broad-band emission that could signify an alien presence through the leakage of beamed propulsion in the star system. Beamed propulsion is one hypothetical method that could be used to power spacecraft in the future, so if there’s an alien megastructure around that star, there would likely be spacecraft too, possibly sporting this propulsion method.

“This is the first time we’ve used the Allen Telescope Array to look for relatively wide-band signals, a type of emission that is generally not considered in SETI searches,” said SETI Institute scientist Gerry Harp in a news release.

A new tool provides speedy analysis of gene expression patterns in individual neurons from postmortem brain tissue. Researchers have used the method to compare the genetic signatures of more than 3,000 neurons from distant brain regions.

Scientists typically use a technique called RNA-Seq to measure gene expression in neurons isolated from postmortem brains. However, analyzing the data from this approach is daunting because the analysis must be done one cell at a time.

The new method combines RNA-Seq with software that allows researchers to analyze the expression patterns of thousands of neurons at once1. The investigators described the automated technique, called single-nucleus RNA sequencing (SNS), in June in Science.

The researchers tested the method on postmortem brain tissue from a 51-year-old woman with no known neurological illnesses. They used a laser to dissect 3,227 neurons from six brain areas, including those involved in language, cognition, vision and social behavior. They then performed RNA-Seq on the cells, getting a readout for RNAs produced in each cell.

The software identifies genes by matching a short segment of each RNA to a gene on a reference map of the human genome. The researchers then quantified each gene’s expression level.

The process correctly identified the subtypes of 2,253 neurons that ramp up brain activity and 972 neurons that dampen it.

Within these two broad classes, the neurons fell into 16 groups based on their location and their origin in the developing brain. For example, neurons from the visual cortex show different patterns of gene expression than do neurons from the temporal cortex, which processes hearing and language.

The findings expand the list of features that distinguish neurons from other cells in the brain. Researchers could use the method to identify patterns of gene expression in the brains of people with autism.

MIT engineers have developed a microfluidic device that replicates the neuromuscular junction — the vital connection where nerve meets muscle. The device, about the size of a U.S. quarter, contains a single muscle strip and a small set of motor neurons. Researchers can influence and observe the interactions between the two, within a realistic, three-dimensional matrix.

The researchers genetically modified the neurons in the device to respond to light. By shining light directly on the neurons, they can precisely stimulate these cells, which in turn send signals to excite the muscle fiber. The researchers also measured the force the muscle exerts within the device as it twitches or contracts in response.

The team’s results, published online today in Science Advances, may help scientists understand and identify drugs to treat amyotrophic lateral sclerosis (ALS), more commonly known as Lou Gehrig’s disease, as well as other neuromuscular-related conditions.

Artificial intelligence gives technology the ability to learn and adapt. But they can learn a lot more if they can share their learning with other smart devices.

Take a look around and you’ll see evidence of the widespread adoption of wearable sensors for health and fitness, such as the Fitbit, Garmin or other devices. What many people many not know is that we are also using sensors to monitor the structural integrity of bridges and buildings, as well as tracking the movements of insects and other animals.

With the rapid growth of the Internet of Things (IoT), tens of billions of sensor devices are projected to connect in the next decade. These connected sensor devices will automate processes across a broad range of economic sectors, from industrial plants to healthcare management, delivering productivity gains and hopefully quality-of-life improvements.

The core of these sensor devices that will be deployed across this broad range of applications is largely the same, featuring a microprocessor, memory and a wired or wireless communication interface to the internet, along with a battery or other energy source.

Each application and IoT device will bring its own unique context, such as its location, the conditions of the surrounding environment and the behavior of people in the area. Individual devices will observe and adapt to their unique contexts.

So what happens when we introduce artificial intelligence (AI) into the mix? With AI, these devices can evolve their behavior in response to changing contexts. Just like how living beings optimize their behavior to their surroundings, even smaller IoT devices around us can run AI machines that evolve their software over time.

Physicists at the Large Hadron Collider (LHC) in Europe have explored the properties of nature at higher energies than ever before, and they have found something profound: nothing new.

It’s perhaps the one thing that no one predicted 30 years ago when the project was first conceived.

The infamous “diphoton bump” that arose in data plots in December has disappeared, indicating that it was a fleeting statistical fluctuation rather than a revolutionary new fundamental particle. And in fact, the machine’s collisions have so far conjured up no particles at all beyond those catalogued in the long-reigning but incomplete “Standard Model” of particle physics. In the collision debris, physicists have found no particles that could comprise dark matter, no siblings or cousins of the Higgs boson, no sign of extra dimensions, no leptoquarks — and above all, none of the desperately sought supersymmetry particles that would round out equations and satisfy “naturalness,” a deep principle about how the laws of nature ought to work.

“It’s striking that we’ve thought about these things for 30 years and we have not made one correct prediction that they have seen,” said Nima Arkani-Hamed, a professor of physics at the Institute for Advanced Study in Princeton, N.J.

Silicon memory chips come in two broad types: volatile memory, such as computer RAM that loses data when the power is turned off, and nonvolatile flash technologies that store information even after we shut off our smartphones.

In general, volatile memory is much faster than nonvolatile storage, so engineers often balance speed and retention when picking the best memory for the task. That's why slower flash is used for permanent storage. Speedy RAM, on the other hand, works with processors to store data during computations because it operates at speeds measured in nanoseconds, or billionths of a second.

Now Stanford-led research shows that an emerging memory technology, based on a new class of semiconductor materials, could deliver the best of both worlds, storing data permanently while allowing certain operations to occur up to a thousand times faster than today's memory devices. The new approach may also be more energy efficient.

"This work is fundamental but promising," said Aaron Lindenberg, an associate professor of materials science and engineering at Stanford and of photon science at the SLAC National Accelerator Laboratory. "A thousandfold increase in speed coupled with lower energy use suggests a path toward future memory technologies that could far outperform anything previously demonstrated."

Lindenberg led a 19-member team, including researchers at SLAC, who detailed their experiments in Physical Review Letters. Their findings provide new insights into the experimental technology of phase-change memory.

Working together, wall-climbing robots weave a suspended web strong enough to hold a person.

Yablonina's mobile robotic fabrication system for filament structures features two semi-autonomous bots working together to distribute thread. They climb walls using suction and sensing technology, and can construct a hammock-like web strong enough to support a person. Yablonina developed the project as part of her grad program at the University of Stuttgart's Institute for Computational Design.

Each bot contains pathfinding software to navigate walls and electromagnets that allow them to pass the bobbin to each other. They're also equipped with a wrapping mechanism so they can wind the cord around an anchor and have it stay in place.

"These robots are enabled with movement systems and a collection of sensors that allow them to travel and interact accurately along typical ground, walls, roofs, and ceilings," Yablonina explained in her project description. She envisions them being part of a "suitcase housing" scenario, where an operator lets the bots loose to construct a large structure onsite.

Yablonina was on the university team behind the Elytra Filament Pavilion, a robotically fabricated modular outdoor structure on display at the Victoria and Albert Museum in London. Since receiving her masters degree, she joined the software company Autodesk as an artist in residence. One recent project is a robot cut from a single sheet of material, folded into shape, and enabled by a single actuator.

Last month, Ars Technica reported on a small but enduring mystery in cosmology: why is there so much of one isotope of lithium around? Both 6Li and 7Li should have been produced when the first atoms formed after the Big Bang, but how much of them should have been made?

The question comes down to basic nuclear physics. When two hydrogen atoms collide under pressure, what is the probability that they will make helium? That sort of physics also applies to collisions between other elements, some of which produce lithium. It is an astonishing achievement that cosmologists can, from basic physics, predict the relative fractions of hydrogen and helium produced in the Big Bang. It is just as astonishing that we can look back in time and measure these fractions and know that cosmologists have it almost exactly right.

Almost. These calculations fall flat when it comes to lithium. They suggest there should be much more 7Li than we observe in the Universe and a lot less 6Li. Does that mean the estimates are wrong, or is there a real discrepancy? New experiments indicate that when it comes to 6Li, the problem seems to be with the Universe and not our calculations.

Part of the problem is that lithium can also be produced and burned in stars, so it's harder to determine how much of what we see represents the primordial fraction. And there are more ways to make heavier elements, making our calculations more uncertain. For now, no one is entirely sure if there is a problem or not.

Physical Review Letters, 2016, DOI: 10.1103/PhysRevLett.117.035002

Surfaces that discourage bacterial growth are in high demand, particularly as more patients require catheters and implants. Last month, we reported on a new anti-bacterial surface that incorporates molecular compounds that can block bacteria’s ability to communicate and form biofilms, which interferes with their capacity to resist antibiotics and coordinate an assault on the host.

On such an implant, human cells and bacterial cells compete to colonize the surface. Obviously, any surface that can give the upper hand to human cells is preferable. So, an international team of researchers used “nano-topology” to devise a surface that physically rips apart bacteria while leaving human cells alone. The team was aware of prior research on dragonfly wings, which are composed of bactericidal nano-structures. A synthetic material with similar bactericidal properties is called black silicon. As shown in the image above, black silicon is made up of tiny spikes, reminiscent of a bed of nails. Because bacteria are very tiny, these spikes place tremendous mechanical stress on them, and they rupture. But human (i.e., eukaryotic) cells are gigantic by comparison. Like a human laying on a bed of nails, these cells should, in theory, be just fine.

To test this, the team coated surfaces with either black silicon (bSi) or regular silicon (Si), and pre-infected them with either Pseudomonas aeruginosa or Staphylococcus aureus, both human pathogens. Then, they added cells from monkey kidneys (called COS-7 cells) to determine how they fared in the presence of pathogens with or without black silicon. The result shows that bacteria get selectively killed by such a surface.

Fertilization is a critical process for starting new life and begins with the fusion between sperm and egg. In the steps of sperm-egg fusion, IZUMO1 on the spermatozoon and the IZUMO1 counter-receptor on the egg, JUNO, play crucial roles in the very first step, the formation of an intercellular bridge (Fig. 1), and deletion of either gene leads to the failure of gamete membrane fusion. However, the molecular mechanism by which JUNO specifically recognizes IZUMO and participates in the sperm-egg adhesion step remains to be fully understood.

A research group led by Kazuki Kato, then-graduate student, Hiroshi Nishimasu, assistant professor, and Osamu Nureki, professor, at the Graduate School of Science, The University of Tokyo, and Yuhkoh Satouh, assistant professor, and Masahito Ikawa, professor, at the Research Institute for Microbial Diseases, Osaka University, has analyzed the detailed structure and function of the JUNO protein. This group crystallized the mouse JUNO protein and, as a result of X-ray crystal structure analysis, determined the crystal structure of JUNO by molecular replacement at 2.3Å resolution. They also found that JUNO and folate receptors have similar overall structures, but JUNO lacks the folate-binding pocket, thereby explaining the inability of JUNO to bind folate.

University of Cambridge physicist Luke Butcher has uploaded a paper to the arXiv preprint server suggesting that there might exist some type of wormhole that is capable of staying open long enough for a photon to pass through.

Time travel, is still of course, the purview of science fiction writers and daydreamers, though physicists believe that at least in theory, it should be possible. It was Albert Einstein who first suggested one possibility: the wormhole—a tunnel through space time that could conceivably have one end in one place in time and the other, in another. There was one serious catch however, preventing us humans from building a vehicle of some sort and running through such a wormhole—they only exist for very short periods of time, not nearly enough for a person, much less a single particle or photon to enter and pass through. Because of that, the possibility of time travel came to a standstill, at least until 1988, when physicist Kip Thorne proposed an idea where a wormhole could be kept open longer.

He suggested that wormholes might be kept open though the use of negative energy, aka Casimir energy. While the idea seemed promising no one was able to think of a way to cause the creation of Casimir energy to occur inside a wormhole, while a human vehicle passed through. In his paper, Butcher suggests that there might be another way—by taking advantage of Casimir energy that exists naturally in some wormholes.

He did a lot of calculating and found that if a wormhole was a lot longer than it is wide, the amount of Casimir energy present inside of it would be enough to cause it to stay open longer than normal. Just long enough, Butcher suggests, to send a photon through.

It's all still theoretical, he acknowledges, and there are other parts of wormholes that aren't understood, some of which might prevent the movement of a photon, or human vehicle, for example. So, it's not like time travel is about to become a reality. It's more likely, he suggests, that his idea will spur further research and perhaps initiate new ideas that could possibly someday lead to some form of time travel.