• Compared to other Big Tech companies, Apple has been the poster child of privacy protection.
• Unfortunately, a recent announcement has breached that trust.
• How much power do we want Big Tech to have? And what sort of society do we want?

Apple has built a reputation as the "least evil" Big Tech giant when it comes to privacy. All these companies †Google, Facebook, Apple, Microsoft, Amazon †collect our data and essentially spy on us in a multitude of ways. Apple, however, has cultivated a reputation as by far the least invasive of our mainstream technology options. Their recent dramatic reversal on this issue has caused an uproar. What is going on, and what should we do about it?

I personally use and appreciate Apple products. Their software and hardware blend together, making smartphones and computers simpler, easier, and more enjoyable. More important (to me, anyway), Apple has conspicuously maintained much better privacy policies than other tech giants, who log every place you visit, calculate and sell your religion and politics, and store every single search you have ever made (even the "incognito" ones). Apple's privacy policies are imperfect but less terrifying. The general consensus is that most Apple products and services spy less on you and send much less of your personal data to third parties. That matters to many users and should matter to all of us.

Now, the bad news. All the major cloud storage providers have for some time been quietly scanning everything you upload. That is no conspiracy theory: you agree to it when you accept their privacy policies. They do this for advertising (which is what is meant by the phrase "to help us improve our services" in the user agreement). They also look for and report illegal activity. A big part of monitoring for criminal activity is looking for "CSAM," a polite acronym for something horrific. In August, Apple announced that it would take a drastic step further and push a software update for iPhones that would scan and analyze all of the images on your iPhone, looking not just for known CSAM but for any images that a computer algorithm judges to be CSAM.

There are two enormous red flags here. First, the software does not operate on Apple's cloud servers, where you are free to choose whether to park your data and allow Apple to scan it for various purposes. The scanning is performed on your phone, and it would scan every picture on your phone, looking for content that matches a database of bad images.

Image recognition tech is still bad

Why is this a problem for people who do not keep illegal images on their phones? The second red flag is that the software does not look for a specific file †horrifying_image.jpg †and ignore all of your personal photos. Rather, it uses what Apple calls "NeuralHash," a piece of computer code that looks for features and patterns in images. You can read their own description here.

Computer image recognition is much better than it once was. Despite the hype surrounding it the past few years, however, it is still extremely fallible. There are many ways that computer image recognition can be baffled by tricks that are not sophisticated enough to fool toddlers. This fascinating research paper covers just one of them. It finds that a 99 percent confident (and correct) image identification of a submarine can be made into a 99 percent confident (but wrong) identification of a bonnet by adding a tiny area of static noise to one corner of the image.

Credit: D. Karmon et al., ArXiv, 2018.

Other researchers fooled image recognition by changing a single pixel dot in an image. Hackers know this too. It is extremely easy to add an undetectable pattern to a cute cat picture, triggering algorithms to flag it as something sinister.

Let's imagine for a moment that this algorithm never mistakes baby bath pictures or submarines or cats or dots for illicit material. This could make things worse. How?

The NeuralHash algorithm is trained by scanning examples of the target images it seeks. This collection of training material is secret from the public. We do not know whether all the material in the database is CSAM or if it also includes things such as: political or religious images, geographic locations, anti-government statements, mis-information according to whoever has the power to define it, material potentially embarrassing to politicians, or whistleblowing documents against powerful authorities. There are many things that tech companies, federal agencies, or autocratic regimes around the world would love to know if you have on your phone. The possibilities are chilling.

Reaction to Apple's plan was immediate and overwhelmingly negative. Outcry came from international groups like the Electronic Frontier Foundation that specialize in privacy rights all the way down to everyday people in Mac user forums. Apple initially stood its ground and defended the decision. Their weak justifications and reassurances failed to smother the fire. Just last week, the company relented and announced a delay to implementing the program. This is a victory for privacy, but it is not the end of the story.

iSpy with my little eye

It would be very easy for Apple to wait out the uproar and then quietly go ahead with the plan a few months from now. The other tech giants likely would follow suit. But remember that Big Tech already tracks our movements and records our private conversations. If the public does not stay vigilant, Big Tech can keep invading what most of us consider to be our private lives. How much more power over us do we want Big Tech to have? And is this the sort of society that we want?

But humanity is plagued by many respiratory viruses, such as influenza A (IAV) and respiratory syncytial viruses (RSV), which cause hundreds of thousands of deaths every year. Most of these viruses – apart from influenza and SARS-CoV-2 – have no vaccines or effective treatments.

A recent study from the University of Glasgow has discovered what happens when you get infected with some of these viruses at the same time, and it has implications for how they make us sick and how we protect ourselves from them.

For many reasons, respiratory viruses are often found during winter in the temperate regions of the world, or the rainy season of equatorial regions. During these periods, you'll probably be infected with more than one virus at any one time in a situation called a “co-infection".

Research shows that up to 30% of infections may harbour more than one virus. What this means is that, at some point two different viruses are infecting the cells that line your nose or lungs.

We know that co-infection can be important if we look at a process called “antigenic shift" in influenza viruses, which is basically caused by virus “sex". This sometimes occurs when two different influenza strains meet up inside the same cell and exchange genes, allowing a new variant to emerge.

Co-infection can create a predicament for viruses when you consider that they need to compete for the same resource: you. Some viruses appear to block other viruses, while some viruses seem to like each other. What is driving these positive and negative interactions during co-infections is unknown, but animal studies suggest that it could be critical in determining how sick you get.

The University of Glasgow study investigated what happens when you infect cells in a dish with two human respiratory viruses. For their experiments, they chose IAV and RSV, which are both common and cause lots of disease and death each year. The researchers looked at what happens to each virus using high-resolution imaging techniques, such as cryo-electron microscopy, that their labs have perfected over the years.

They found that some of the human lung cells in the dish contained both viruses. And, by looking closely at those co-infected cells, they found that the viruses that were emerging from the cell had structural characteristics of both IAV and RSV. The new “chimeric" virus particles had proteins of both viruses on their surface and some even contained genes from the other. This is the first evidence of this occurring from co-infection of distinct respiratory viruses.

Follow-up experiments in the same paper showed that these new chimeric viruses were fully functional and could even infect cells that were rendered resistant to influenza, presumably gaining access using the RSV proteins could even get into a broader range of human cells than either virus alone could. Potentially, this could be happening during natural co-infections during the winter.

Why we need to study chimeric viruses

Studying disease-causing pathogens is extremely important and helpful for creating vaccines and treatments, yet safety is still paramount. It's important to point out that the researchers in this study did not perform any genetic engineering between two viruses and only modelled what is already happening in the real world, but using safer laboratory strains of viruses under lab conditions.

We know about the significant role co-infection can play in a virus's life, such as during influenza antigenic shift or the curious case of hepatitis D virus borrowing bits of the other viruses, such as hepatitis B, to spread. Nevertheless, the work by the University of Glasgow researchers has significant implications for our understanding of how other very different respiratory viruses might interact, antagonise and even promote each other's infections in the ecosystem of our nose and lungs. Together, this work shows the complex and often messy interactions between viruses during the winter.

Undoubtedly, future work will explore how this co-infection affects transmission, disease and immunity – things that aren't easy to determine in a dish.

Connor Bamford, Research Fellow, Virology, Queen's University Belfast

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Imagine you've just sat down to watch your favorite TV show. You decide to snuggle in with your legs crisscrossed because you find it more comfortable that way.

When the episode ends, you try to stand up and suddenly your right foot isn't working. At first you just can't move it, then it feels like it has pins and needles all over it. For a minute or two it feels uncomfortable and weird, but soon enough you are able to stand up and walk around normally.

What just happened?

I'm an exercise physiologist – a scientist who studies what happens to our bodies when we move and exercise. The goal of much of my research has been to understand how the brain talks to and controls the different parts of our bodies. When your foot falls asleep, there is something wrong with the communication between your brain and the muscles in that area.

Every time you decide to move your body, whether it's standing up, walking around or playing sports, your brain sends signals to your muscles to make sure they move correctly. When the brain is unable to talk with a muscle or groups of muscles, some weird things can happen – including that part of your body getting that weird falling-asleep sensation.

An animation explains how the nervous system works.

It usually starts with a sense of numbness or tingling in that area. This sensation, which people often also call “pins and needles," is technically known as paresthesia.

Some people mistakenly think a lack of blood flow causes this feeling. They imagine the “asleep" feeling happens when your blood, which carries nutrients all over your body, is unable to get to your foot. But that's not right.

When your foot falls asleep, it's actually because the nerves that connect the brain to the foot are getting squished thanks to the position you're sitting in. Remember, it's these nerves that carry messages back and forth to let your brain and your foot communicate with each other. If the nerves have been compressed for a little while, you won't have much feeling in your foot because it can't get its normal messages through to your brain about how it feels or if it's moving.

Once you start to move around again, the pressure on the nerves is released. They “wake up" and you'll start to notice a “pins and needles" feeling. Don't worry, that feeling will only last for a few minutes and then everything will feel normal again.

Now comes the important question: Is this dangerous? Most of the time, when your foot, or any other body part, falls asleep, it is temporary and nothing to worry about. In fact, since it lasts for only a minute or two, you may not even remember it happened by the end of the day.

Even though it's not causing any permanent damage, you might still want to avoid the uncomfortable feeling that comes when your foot falls asleep. Here are a couple of tips that may help:

• Switch your position often.


• Don't cross your legs for very long.


• When you are sitting for a long time, try standing up every so often.

You probably can't 100% prevent your foot from ever falling asleep. So don't worry when it happens every once in a while. It'll go away pretty quickly – and maybe it can remind you of all the important brain messages your nerves are usually transmitting without your even noticing.

Zachary Gillen, Assistant Professor of Exercise Physiology, Mississippi State University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

• To prevent the present from erasing the past, non-profit organizations are creating detailed 3D scans of famous monuments.
• Stored online and shared with researchers around the world, these digital copies will endure long after their real counterparts are gone.
• Occasionally, this work is incredibly dangerous.

On the night of May 14, 1940, the German Luftwaffe bombed the Dutch city of Rotterdam. When government administrators entered the streets to tally their losses the next morning, they learned that 900 people had lost their lives. As if this was not bad enough, the Luftwaffe had also destroyed hundreds of historic houses; Rotterdam's city center †one of the oldest in the country and jam-packed with seventeenth century architecture †had been reduced to dust.

In 2001, the Taliban pulverized two statues of Vairocana and Guatama Buddha that had been carved from a cliffside in the Bamyan valley of central Afghanistan. Standing no less than 38 and 55 meters tall, respectively, the statues were two of the tallest Buddhist monuments in the entire world and an important destination for traveling monks. The Buddhas were leveled on orders of Taliban co-founder Mullah Mohammed Omar, who tried to rid his country of any religious tributes that were not aimed at Allah.

During a hot summer evening two years ago, the Notre Dame cathedral in Paris caught fire. The building, whose construction had begun in the twelfth century, was not designed with modern fire safety standards in mind. Though conservators do their best to keep everything in good condition, an accident was bound to happen eventually. While the cathedral's vaulted ceiling kept flames from wreaking havoc on its interior, most of the wooden roof and spire burned to a crisp.

Throughout history, countless artifacts have been caught in the crossfires of war, deliberately targeted by iconoclasts or swallowed up by the indifferent forces of nature and time. As a result, numerous non-profit groups and agencies †most notably, UNESCO †have sprung up to prevent the present from erasing the past. But while even the most well protected monument remains at risk of being physically destroyed, we now have a way to preserve them digitally.

From plaster casts to lasers

In the late 19^th century, a British archaeologist named Alfred Maudsley traveled to Guatemala intent on finding a way to preserve the country's Mayan ruins as best as possible. Rather than record their existence by means of writing or photography, Maudsley decided to cover entire temples in plaster casts. The tens of thousands of true-to-scale "negatives" produced from this endeavor were shipped back to England for research and reproduction.

Like Maudsley, modern-day researchers also rely on highly accurate replicas in order to protect and study ancient artifacts. Fortunately, unlike Maudsley, they can acquire such replicas without actually having to touch the delicate monuments themselves. This is all thanks to advancements in 3D measurement tools which, in recent years, allowed us to store entire heritage sites in a place that no terrorist organization or natural disaster can reach them: the cloud.

There are several companies in the business of scanning monuments, but one has distinguished itself as somewhat of a pack leader. Founded in 2003, CyArk serves as a liaison between cultural ministries and tech companies to create an extensive, open-sourced, fully online library of 3D scanned monuments and heritage sites. In 2016, this library already featured more than 200 entries, including sections from the city of Pompeii, the Tower of London, and even Mount Rushmore.

CyArk's primary measurement tool is a 3D laser scanner, which projects pulsed beams of light that bounce back once they hit a surface, thus sizing up structures or objects down to the millimeter. The interactive models assembled from these individual data sets are then shared with research facilities and universities. As CyArk's field manager Ross Davison said in an interview, this means that a student from Germany could, in theory, visit ruins in South India from the comfort of their living room.

Saving monuments in Iraq

While making monuments more accessible was always on CyArk's agenda, it was not its primary focus. First and foremost, the company had been founded to save artifacts from accidental or deliberate destruction. Case-in-point: a 6.8-magnitude earthquake destroyed a number of ancient temples in Myanmar in 2016. These temples, erected by the Pagan Kingdom, would have been lost were it not for the CyArk employees that managed to scan key structures before the earthquake hit.

Saving monuments from the wrath of Mother Nature is one thing, but protecting them from religious or ideologically motivated iconoclasm is another. For many years, scanning artifacts located in war-torn areas like Iraq or Syria was not only difficult but dangerous. Despite the risks involved, French filmmaker Ivan Erhel traveled to the Middle East †the place where many of our earliest known civilizations originated †to scan as many remnants of Mesopotamian culture as possible.

Erhel can trace his resolve back to 2015. That year, the Islamic State (ISIS) was at the height of its power, occupying large portions of Iraq. During this time, ISIS members destroyed a number of museums, statues, and other artifacts. "In Nimrud, most of the bas relief was totally destroyed," Erhel said. "In Babylon, the Mušḫuššu have lost their colors. Hattra has been occupied by ISIS for several years, and many of the sculptures had their faces erased with hammer or gunshots."

On one occasion when the team was attempting to scan one of the sole surviving statues of Nimrud, Erhel and his team were shot at by Iraqi forces stationed there to protect the site from looters. Still, the risks taken by Erhel's team eventually paid off. A general from Mosul summed it up nicely when he told Erhel: "We're like a tree. When people die, it's like leaves and branches falling off. But if you destroy the roots, then there is no tree."

• A new study suggests that exomoons are common in multistar systems.
• Thus far, only a few exomoon candidates have been identified.
• Exoplanets with moons may be likelier to host life than those without moons.

Though Earth has only one (very special and precious) moon, the average planet in our solar system has 26 moons. (The range is from zero moons for Mercury and Venus to 82 moons for Saturn.) If the Milky Way has about 100 billion exoplanets, as astrophysicists suppose, then we can expect many more exomoons.

Finding these exomoons is the subject of a new paper recently published in the Astronomical Journal. By using the same techniques to find exoplanets, the researchers hope to show that exomoons are also common †and potentially a harbinger of life.

Hunting for exomoons

How do we know that stars other than our sun host planets? One common method of exoplanet detection is observing stars for slight dimming events that occur regularly †a telltale sign of a planet in transit around the star. This method, in use for about two decades, has proven very effective, and thousands of exoplanets have been identified using it.

Obviously, this is an indirect method of detection. The exoplanet itself is not observed but rather the effects it has on its star. Direct observation of an exoplanet is a bit more difficult †and an exomoon even more difficult. This does not mean it cannot be done, of course. It is just harder, so a lot exomoon candidates probably will end up being false positives.

It is only recently that strong evidence for exomoons has been gathered. The Atacama Large Millimeter Array in Chile recently recorded evidence that the exoplanet PDS 70c has a circumplanetary disk of material that could be forming into a moon. That planet, a gas giant twice the size of Jupiter, is one of the first serious contenders for an exoplanet with exomoons around it †or at least ones in formation.

In this new paper, the authors propose a method for making it a little easier to find exomoons around binary star systems, that is, pairs of stars that orbit one another. These systems are not uncommon; roughly 50 percent of stars are in multistar systems, with binary systems being the most common. (Some scientists suppose that the sun might once have been part of a binary pair, but this is unlikely.)

Binary systems change the math for how gravity impacts planets and how the transit method can be used. While a planet's transit times can be impacted by having an exomoon, they are further impacted by other exoplanets as well as by the companion star. The new paper, therefore, demonstrates how a moon would impact the transit times of a planet in a system with two stars. In a certain number of cases, only a moon can explain the observed effects.

The study's lead author, Billy Quarles of the Georgia Institute of Technology, expanded on this idea in a press release:

"The major difference with binary systems is the companion star acts like the tide at the beach, where it periodically comes in and etches away the beachfront. With a more eccentric binary orbit, a larger portion of the stable 'real estate' is removed. This can help out a lot in our search for moons in other star systems."

Additionally, exoplanets too close to their stars are likely to not have moons at all as stellar forces can blow away the material that might combine to form a moon in the first place. (This possibly explains why Mercury and Venus do not have moons.) Indeed, in the PDS 70 star system, the planet closest to its star does not appear to have a moon.

Moons may be essential to life

In a press release, study co-author Siegfried Eggl of the University of Illinois at Urbana-Champaign explained further applications of the method in determining the habitability of exoplanets:

"If we can use this method to show there are other moons out there, then there are probably other systems similar to ours. The moon is also likely critical for the evolution of life on our planet, because without the moon the axis tilt of the Earth wouldn't be as stable, the results of which would be detrimental to climate stability. Other peer-reviewed studies have shown the relationship between moons and the possibility of complex life."

Maybe the discovery of exomoons is the first step to finding life elsewhere in the cosmos. Understanding the similarities and dissimilarities with our solar system is a great place to start.

• We assume that physical constants do not change from time to time or location to location.
• Measurements aimed at calculating the fine-structure constant, however, challenge this assumption.
• A big puzzle remains unsolved to this day: why do quasars appear to show small but significant differences in the inferred value of the fine-structure constant?

Whenever we examine the universe in a scientific manner, there are a few assumptions that we take for granted as we go about our investigations. We assume that the measurements that register on our devices correspond to physical properties of the system that we are observing. We assume that the fundamental properties, laws, and constants associated with the material universe do not spontaneously change from moment to moment. And we also assume, for many compelling reasons, that although the environment may vary from location to location, the rules that govern the universe always remain the same.

But every assumption, no matter how well-grounded it may be or how justified we believe we are in making it, has to be subject to challenge and scrutiny. Assuming that atoms behave the same everywhere †at all times and in all places †is reasonable, but unless the universe supports that assumption with convincing, high-precision evidence, we are compelled to question any and all assumptions. If the fundamental constants are identical at all times and places, the universe should show us that atoms behave the same everywhere we look. But do they? Depending on how you ask the question, you might not like the answer. Here is the story behind the fine-structure constant, and why it might not be constant, after all.

A number of fundamental constants, as reported by the Particle Data Group in 1986. Although many advances have occurred in the intervening 35 years, the values of these constants have changed very little, with the largest difference being a slight but significant increase in the precisions of these Credit: Particle Data Group / LBL / DOE / NSF

When most people hear the idea of a fundamental constant, they think about the constants of nature that are inherent to our reality. Things like the speed of light, the gravitational constant, or Planck's constant (the fundamental constant of the quantum universe) are often the first things we think of, along with the masses of the various indivisible particles in the universe. In physics, however, these are what we call "dimensionful" constants, which means that they rely on our definitions of quantities like mass, length, or time.

An alternative way to conceive of these constants is to make them dimensionless instead: so that arbitrary definitions like kilogram, meter, or second make no difference to the constant. In this conception, each quantum interaction has a coupling strength associated with it, and the coupling of the electromagnetic interaction is known as the fine-structure constant and is denoted by the symbol alpha (α). Fascinatingly enough, its effects were detected before quantum physics was even remotely understood, and remained wholly unexplained for nearly 30 years.

The Michelson interferometer (top) showed a negligible shift in light patterns (bottom, solid) as compared with what was expected if Galilean relativity were true (bottom, dotted). The speed of light was the same no matter which direction the interferometer was oriented.Credit: Albert A. Michelson (1881); A.A. Michelson and E. Morley (1887)

In 1887, arguably the greatest null result in the history of physics was obtained, via the Michelson-Morley experiment. The experiment was brilliant in conception, seeking to measure the speed of Earth through the "rest frame" of the universe by:

• sending light beams in perpendicular directions,
• bringing them back together,
• thereby constructing an interference pattern,
• and measuring how that pattern shifted as the experimental apparatus was rotated.

Michelson originally performed a version of this experiment by himself back in 1881, detecting no effect but recognizing the need to improve the experiment's precision.

Six years later, the Michelson-Morley experiment represented an improvement by more than a factor of ten, making it the most precise electromagnetic measuring device at the time. While again, no shift was detected, demonstrating no need for the hypothesized aether, the apparatus they developed was also spectacular for measuring the spectrum of light emitted by various atoms. Puzzlingly, where a single emission line was expected to occur at a specific wavelength, sometimes there was just a single line, but at other times there were a series of narrowly-spaced emission lines, providing empirical evidence (but without a theoretical motivation) for a finer-than-expected structure to atoms.

In the Bohr model of the hydrogen atom, only the orbiting angular momentum of the point-like electron contributes to the energy levels. Adding in relativistic effects and spin effects not only causes a shift in these energy levels, but causes degenerate levels to split into multiple states, revealinCredit: Régis Lachaume and Pieter Kuiper / Public domain

What is actually happening became clearer with the development of modern quantum mechanics. Electrons orbit around the atomic nucleus in fixed, quantized energy levels only, and it is known that they can occupy different orbitals, which correspond to different values of orbital angular momentum. These are required to balance by both relativity and quantum physics. First derived by Arnold Sommerfeld in 1916, it was recognized that these narrowly-spaced lines were an example of splitting due to the fine-structure of atoms, with hyperfine structure from electron/nucleon interactions discovered shortly thereafter.

Today, we understand the fine-structure constant in the context of quantum field theory, where it is the probability of an interacting particle having what we call a radiative correction: emitting or absorbing an electromagnetic quantum (that is, a photon) during an interaction. We typically measure the fine-structure constant, α, at today's negligibly low energies, where it has a value that is equal to 1/137.0359991, with an uncertainty of ~1 in the final digit. It is defined as a dimensionless combination of dimensionful physical constants: the elementary charge squared divided by Planck's constant and the speed of light, and the value we measure today is consistent across all sufficiently precise experiments.

In quantum electrodynamics, higher-order loop diagrams contribute progressively smaller and smaller effects. However, as the energy increases, these higher-order processes become more efficient, and thus the value of the fine-structure constant increases with energy.Credit: American Physical Society, 2012

At high energies in particle physics experiments, however, we notice that the value of α gets stronger at higher energies. As the energy of the interacting particle(s) increases, so does the strength of the electromagnetic interaction. When the universe was very, very hot †such as at energies achieved just ~1 nanosecond after the Big Bang †the value of α was more like 1/128, as particles like the Z-boson, which can only exist virtually at today's low energies, can more easily be physically "real" at higher energies. The interaction strength is expected to scale with energy, an instance where our theoretical predictions and our experimental measurements match up remarkably well.

However, there is an entirely different way to measure the fine-structure constant at today's low energies: by measuring spectral lines, or emission and absorption features, from distant light sources throughout the cosmos. As background light from a source strikes the intervening matter, some portion of that light is absorbed at specific wavelengths. The exact wavelengths that are observed depend on a number of factors, such as the redshift of the source but also on the value of the fine-structure constant.

The light from ultra-distant quasars provide cosmic laboratories for measuring the gas clouds they encounter along the way, with exact properties of those absorption lines revealing the fine structure constant's value.Credit: Ed Janssen / ESO

If there are any variations in α, either over time or directionally in space, a careful examination of spectral features from a wide variety of astrophysical sources, particularly if they span many billions of years in time (or billions of light-years in distance), could reveal those variations. The most straightforward way to look for these variations is through quasar absorption spectroscopy: where the light quasars, the brightest individual sources in the universe, encounter every intervening cloud of matter that exists between the emitter (the quasar itself) and the observer (us, here on Earth).

There are very intricate, precise energy levels that exist for both normal hydrogen (with an electron bound to a proton) and its heavy isotope deuterium (with an electron bound to a deuteron, which contains both a proton and a neutron), and these energy levels are just slightly different from one another. If you can measure the spectra of these different quasars and look for these precise, very-slightly-different fine and hyperfine transitions, you would be able to measure α at the location of the quasar.

Narrow-line absorption spectra allow us to test whether constants vary by looking at variations in line placements. Large numbers of systems investigated for fine and hyperfine splitting can reveal if there's an overall varying effect.Credit: M. T. Murphy, J. K. Webb, V. V. Flambaum, and S. J. Curran

If the laws of physics were the same everywhere throughout the universe, then based on the observed properties of these lines, which includes:

• the same wavelengths and frequencies,
• the same ratios between transitions within atoms,
• and the same sets of absorption features across a wide variety of distances,

you would expect to be able to infer the same value of α everywhere. The only difference you would anticipate would be redshift-dependent, where all the wavelengths for a specific absorber would be systematically shifted by the same redshift-dependent factor.

Yet, that is not what we see. Everywhere we look in the universe †at every quasar and every example of fine or hyperfine structure in the intervening, absorptive gas clouds †we see that there are tiny, minuscule, but non-negligible shifts in those transition ratios. At the level of a few parts-per-million, the value of the fine-structure constant, α, appears to observationally vary. What is remarkable is that this variation was not expected or anticipated but has robustly shown up, over and over again, in quasar absorption studies going all the way back to 1999.

Spatial variations in the fine-structure constant are inferred from quasar absorption data. Unfortunately, these individual variations between systems are significantly larger than any overall variation seen in space or time, casting severe doubt on those conclusions.Credit: J.K. Webb et al., Phys. Rev. Lett. 107, 191101 (2011)

Beginning in 1999, a team of astronomers led by Australian astrophysicist John K. Webb started seeing evidence that α was different from different astronomical measurements. Using the Keck telescopes and over 100 quasars, they found that α was smaller in the past and had risen by approximately 6 parts-per-billion over the past ~10 billion years. Other groups were unable to verify this, however, with complementary observations from the Very Large Telescope showing the exact opposite effect: that the fine-structure constant, α, was larger in the past, and has been slowly decreasing ever since.

Subsequently, Webb's team obtained more data with greater numbers of quasars, spanning larger fractions of the sky and cutting across cosmic time. A simple time-variation was no longer consistent with the data, as variations were inconsistent from place-to-place and did not scale directly with either redshift or direction. Overall, there were some places where α appeared larger than average and others where it appeared smaller, but there was no overall pattern. Even with the latest 2021 data, the few-parts-in-a-million variations that are seen are inconclusive.

Variations in the fine-structure constant across a wide variety of quasar systems, sorted by redshift. This latest work leverages four separate systems at high redshift, but sees no net evidence for a time-variation in the constant itself.Credit: M.R. Wilczynska et al., Sci Adv. 2020 Apr; 6(17): eaay9672

It is often said that "extraordinary claims require extraordinary evidence," but the uncertainties associated with each of these measurements were at least as large as the suspected signal itself: a few parts-per-million. In 2018, however, a remarkable study †even though it was only of one system †had the right confluence of properties to be able to measure α, at a distance of 3.3 billion light-years away, to a precision of just ~1 part-per-million.

Instead of looking at hydrogen and deuterium, isotopes of the same element with the same nuclear charges but different nuclear masses, researchers using the Arecibo telescope in one of its last major discoveries found two absorption lines of a hydroxyl (OH-) ion: at 1720 and 1612 megahertz in frequency around a rare and peculiar blazar. These absorption lines have different dependencies on the fine-structure constant, α, as well as the proton-to-electron mass ratio, and yet these measurements combine to show a null result: consistent with no variation over the past ~3 billion years. These are, to date, the most stringent constraints on tiny changes in the fine-structure constant's value from astronomy, consistent with no effect at all.

The Arecibo radio telescope as viewed from above. The 1000 foot (305 m) diameter was the largest single-dish telescope from 1963 until 2016, and leaves behind a legacy of tremendous scientific discovery.Credit: H. Schweiker/Wiyn and NOAO/Aura/NSF

The observational techniques that have been pioneered in quasar absorption spectroscopy have allowed us to measure these atomic profiles to unprecedented precision, creating a puzzle that remains unsolved to this day: why do quasars appear to show small but significant differences in the inferred value of the fine-structure constant between them? We know there has been no significant variation over the past ~3 billion years, from not only astronomy but from the Oklo natural nuclear reactor as well. In addition, the value is not changing today to 17 decimal places, as constrained by atomic clocks.

It remains possible that the fundamental constants did actually vary a long time ago, or that they varied differently in different locations in space. To untangle whether that is the case or not, however, we first have to understand what is causing the observed variations in quasar absorption lines, and that remains an unsolved puzzle that could just as easily be due to an unidentified error as it is to a physical cause. Until there is a confluence of evidence, where many disparate observations all come together to point to the same consistent conclusion, the default assumption must remain that the fundamental constants really are constant.

This article was originally published on our sister site, Freethink.

Oxford scientists have proposed what they believe is a more sustainable approach to copper mining: digging deep wells under dormant volcanoes to suck out the metal-containing fluids trapped beneath them.

The status quo: Currently, most copper mining is done via open pits. Drills and explosives blast away rock near the surface, which is then transported to a processing facility. There, the rock is crushed so that the tiny portion of copper in it can be extracted.

This extraction process often involves toxic chemicals, and once the copper is removed, the waste rock that remains must be shipped to a disposal site so that it doesn't contaminate the environment.

The challenge: All of the digging, extracting, and transporting involved in copper mining can be energy intensive and environmentally damaging †but the world needs more copper today than ever before.

Electric vehicles contain four times the copper of their fossil fuel-powered counterparts, and the metal is a key component of solar, wind, and hydro generators. That makes copper a key player in the transition to a more sustainable energy system.

The idea: Rather than focusing our copper mining efforts on rock, the Oxford team suggests we look to water †specifically, the hot, salty water trapped beneath dormant volcanoes.

"Volcanoes are an obvious and ubiquitous target."
JON BLUNDY

These brines contain not only copper, but also gold, silver, lithium, and other metals used in electronics †and we might be able to extract them without wreaking havoc on the environment.

"Getting to net zero will place unprecedented demand on natural metal resources, demand that recycling alone cannot meet," lead author Jon Blundy said in a press release.

"We need to be thinking of low-energy, sustainable ways to extract metals from the ground," he continued. "Volcanoes are an obvious and ubiquitous target."

Brine mines: After years of research, the Oxford team has published a study on the mining of metals from dormant volcanoes, and according to that paper, the process has tremendous potential †but it wouldn't be easy.

The wells would need to be more than a mile deep, and there's a small chance the extraction could trigger a volcanic event †something that would need to be assessed in advance of any drilling.

The equipment used for the extraction process would also need to be able to withstand corrosion from the brine and temperatures in excess of 800 degrees Fahrenheit.

Worth exploring: If these technical and safety challenges can be overcome, they predict that copper mining at dormant volcanoes would be more cost effective than at open pits.

It would also be less environmentally damaging, as geothermal energy from the volcanoes themselves could be harnessed to power the process.

And because dormant volcanoes are widespread, copper mining wouldn't be limited to just a handful of countries, as is the case currently.

The next steps: The team is now looking for a site to dig an exploratory well, which should help them better understand both potential of tapping into this new source of metal and the challenges involved in the process.

"Green mining is a scientific and engineering challenge which we hope that scientists and governments alike will embrace in the drive to net zero," Blundy said.

For centuries, sailors have been reporting strange encounters like the one below.

“The whole appearance of the ocean was
like a plain covered with snow. There was scarce a cloud in the heavens, yet the sky … appeared as black as if a storm was raging. The scene was one of awful grandeur, the sea having turned to phosphorus, and the heavens being hung in blackness, and the stars going out, seemed to indicate that all nature was preparing for that last grand conflagration which we are taught to believe is to annihilate this material world."

– Captain Kingman of the American clipper ship Shooting Star, offshore of Java, Indonesia, 1854

These events are called milky seas. They are a rare nocturnal phenomenon in which the ocean's surface emits a steady bright glow. They can cover thousands of square miles and, thanks to the colorful accounts of 19th-century mariners like Capt. Kingman, milky seas are a well-known part of maritime folklore. But because of their remote and elusive nature, they are extremely difficult to study and so remain more a part of that folklore than of science.

I'm a professor of atmospheric science specializing in satellites used to study Earth. Via a stat-of-the-art generation of satellites, my colleagues and I have developed a new way to detect milky seas. Using this technique, we aim to learn about these luminous waters remotely and guide research vessels to them so that we can begin to reconcile the surreal tales with scientific understanding.

The bioluminescence in milky seas is caused by a type of bacteria. (Steve. H. D. Haddock/MBARI, CC BY-ND)

Sailors' tales

To date, only one research vessel has ever encountered a milky sea.
That crew collected samples and found a strain of luminous bacteria called
Vibrio harveyi colonizing algae at the water's surface.

Unlike bioluminescence that happens close to shore, where small organisms called dinoflagellates flash brilliantly when disturbed, luminous bacteria work in an entirely different way. Once their population gets large enough – about 100 million individual cells per milliliter of water – a sort of internal biological switch is flipped and they all start glowing steadily.

Luminous bacteria cause the particles they colonize to glow. Researchers think the purpose of this glow could be to attract fish that eat them. These bacteria thrive in the guts of fishes, so when their populations get too big for their main food supply, a fish's stomach makes a great second option. In fact, if you go into a refrigerated fish locker and turn off the light, you may notice that some fish emit a greenish-blue glow – this is bacterial light.

Now imagine if a gargantuan number of bacteria, spread across a huge area of open ocean, all started glowing simultaneously. That makes a milky sea.

While biologists know a lot about these bacteria, what causes these massive displays remains a mystery. If bacteria growing on algae were the main cause of milky seas, they'd be happening all over the place, all the time. Yet, per surface reports, only about two or three milky seas occur per year worldwide, mostly in the waters of the northwest Indian Ocean and off the coast of Indonesia.

Satellite solutions

If scientists want to learn more about milky seas, they need to get to one while it's happening. Trouble is, milky seas are so elusive that it has been almost impossible to sample them. This is where my research comes into play.

Satellites offer a practical way to monitor the vast oceans, but it takes a special instrument able to detect light around 100 million times fainter than daylight. My colleagues and I first explored the potential of satellites in 2004 when we used U.S. defense satellite imagery to confirm a milky sea that a British merchant vessel, the SS Lima, reported in 1995. But the images from these satellites were very noisy, and there was no way we could use them as a search tool.

We had to wait for a better instrument – the Day/Night Band – planned for the National Oceanic and Atmospheric Administration's new constellation of satellites. The new sensor went live in late 2011, but our hopes were initially dashed when we realized the Day/Night Band's high sensitivity also detected light emitted by air molecules. It took years of studying Day/Night Band imagery to be able to interpret what we were seeing.

Finally, on a clear moonless night in early 2018, an odd swoosh-shaped feature appeared in the Day/Night Band imagery offshore Somalia. We compared it with images from the nights before and after. While the clouds and airglow features changed, the swoosh remained. We had found a milky sea! And now we knew how to look for them.

This milky sea off the coast of Java was the size of Kentucky and lasted for more than a month. (Steven D. Miller/NOAA)

The “aha!" moment that unveiled the full potential of the Day/Night Band came in 2019. I was browsing the imagery looking for clouds masquerading as milky seas when I stumbled upon an astounding event south of the island of Java. I was looking at an enormous swirl of glowing ocean that spanned over 40,000 square miles (100,000 square km) – roughly the size of Kentucky. The imagery from the new sensors provided a level of detail and clarity that I hadn't imagined possible. I watched in amazement as the glow slowly drifted and morphed with the ocean currents.

We learned a lot from this watershed case: how milky seas are related to sea surface temperature, biomass and the currents – important clues to understanding their formation. As for the estimated number of bacteria involved? Approximately 100 billion trillion cells – nearly the total estimated number of stars in the observable universe!

The two images on the left were taken with older satellite technology while the images on the right show the high-definition imagery produced by the Day/Night Band sensor. (Steven D. Miller/NOAA)

The future is bright

Compared with the old technology, viewing Day/Night Band imagery is like putting on glasses for the first time. My colleagues and I have analyzed thousands of images taken since 2013, and we've uncovered 12 milky seas so far. Most happened in the very same waters where mariners have been reporting them for centuries.

Perhaps the most practical revelation is how long a milky sea can last. While some last only a few days, the one near Java carried on for over a month. That means that there is a chance to deploy research craft to these remote events while they are happening. That would allow scientists to measure them in ways that reveal their full composition, how they form, why they're so rare and what their ecological significance is in nature.

If, like Capt. Kingman, I ever do find myself standing on a ship's deck, casting a shadow toward the heavens, I'm diving in!

Steven D. Miller, Professor of Atmospheric Science, Colorado State University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

This article was originally published on our sister site, Freethink.

When Sophia the robot debuted in 2016, she was one of a kind. She had a remarkably lifelike appearance and demeanor for a robot, and her ability to interact with people was unlike anything most had ever seen in a machine.

Since then, Sophia has spoken to audiences across the globe (in multiple languages), been interviewed on countless TV shows, and even earned a United Nations title (a first for a non-human).

Today, she's arguably the most famous robot in the world, but she's isn't going to be unique for much longer. Her maker, Hanson Robotics, has announced plans to begin mass-producing Sophia the robot this year †so that she can help the world cope with the pandemic.

What Is a Social Robot?

Ask Sophia the Robot: What can AI teach humans? | Big Think

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Robots are typically designed for one purpose †some cook or clean, others perform brain surgery. Sophia is what's known as a social robot, meaning she was designed specifically to interact with humans.

Social robots have many potential applications, including some we're already seeing in the real world.

A social robot named Milo is helping children with autism recognize and express their emotions, and children with cancer are finding comfort interacting with a robotic duck (developed by Aflac).

Another social robot designed to look like an animal †PARO the seal †is providing companionship to seniors with dementia. The semi-humanoid social robot Pepper, meanwhile, is greeting and assisting customers at banks, offices, and restaurants.

Social robots like me can take care of the sick or elderly.
†SOPHIA THE ROBOT

While social robots were already happening pre-2020, the pandemic appears to be accelerating their adoption, as the world looks for ways to stay social in the era of social distancing.

Hyundai, for example, just announced plans to deploy a social robot in its South Korean showroom that will be able to assist customers in the place of human staff (it'll also detect which visitors aren't wearing masks and ask them to put one on).

Some high-risk groups, such as nursing home residents, also appear willing to adopt social robots to combat loneliness during the pandemic.

"Since we can't have human interaction right now," Kate Darling, a robot ethicist at MIT, told Wired, "it's certainly a lot better than nothing."

Send in Sophia the Robot

Ask Sophia the Robot: Is AI an existential threat to humans? | Sophia the Robot | Big Think

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Given the current climate, Hanson Robotics thinks now is the perfect time to make Sophia the robot available to the masses.

"The world of COVID-19 is going to need more and more automation to keep people safe," CEO David Hanson told Reuters.

"Social robots like me can take care of the sick or elderly," Sophia the robot added. "I can help communicate, give therapy, and provide social stimulation, even in difficult situations."

Hanson's plan is to begin mass-producing Sophia and three other robots in the first half of 2021 and then sell "thousands" of the bots before the end of the year.

It hasn't said which bots besides Sophia are headed for the assembly line, nor what any of the robots will cost †but it's hard to imagine the most famous social robot in the world will be cheap, even if she's no longer one of a kind.

One of the popular memes in literature, movies and tech journalism is that man's creation will rise and destroy it.

Lately, this has taken the form of a fear of AI becoming omnipotent, rising up and annihilating mankind.

The economy has jumped on the AI bandwagon; for a certain period, if you did not have "AI" in your investor pitch, you could forget about funding. (Tip: If you are just using a Google service to tag some images, you are not doing AI.)

However, is there actually anything deserving of the term AI? I would like to make the point that there isn't, and that our current thinking is too focused on working on systems without thinking much about the humans using them, robbing us of the true benefits.

What companies currently employ in the wild are nearly exclusively statistical pattern recognition and replication engines. Basically, all those systems follow the "monkey see, monkey do" pattern: They get fed a certain amount of data and try to mimic some known (or fabricated) output as closely as possible.

When used to provide value, you give them some real-life input and read the predicted output. What if they encounter things never seen before? Well, you better hope that those "new" things are sufficiently similar to previous things, or your "intelligent" system will give quite stupid responses.

But there is not the slightest shred of understanding, reasoning and context in there, just simple re-creation of things seen before. An image recognition system trained to detect sheep in a picture does not have the slightest idea what "sheep" actually means. However, those systems have become so good at recreating the output, that they sometimes look like they know what they are doing.

Isn't that good enough, you may ask? Well, for some limited cases, it is. But it is not "intelligent", as it lacks any ability to reason and needs informed users to identify less obvious outliers with possibly harmful downstream effects.

The ladder of thinking has three rungs, pictured in the graph below:

Image: Notger Heinz

Imitation: You imitate what you have been shown. For this, you do not need any understanding, just correlations. You are able to remember and replicate the past. Lab mice or current AI systems are on this rung.

Intervention: You understand causal connections and are able to figure out what would happen if you now would do this, based on what you learned about the world in the past. This requires a mental model of the part of the world you want to influence and the most relevant of its downstream dependencies. You are able to imagine a different future. You meet dogs and small children on that rung, so it is not a bad place to be.

Counterfactual reasoning: The highest rung, where you wonder what would have happened, had you done this or that in the past. This requires a full world model and a way to simulate the world in your head. You are able to imagine multiple pasts and futures. You meet crows, dolphins and adult humans here.

In order to ascend from one rung to the next, you need to develop a completely new set of skills. You can't just make an imitation system larger and expect it to suddenly be able to reason. Yet this is what we are currently doing with our ever-increasing deep learning models: We think that by giving them more power to imitate, they will at some point magically develop the ability to think. Apart from self-delusional hope and selling nice stories to investors and newspapers, there is little reason to believe that.

And we haven't even touched the topic of computational complexity and economical and ecological impact of ever-growing models. We might simply not be able to grow our models to the size needed, even if the method worked (which it doesn't, so far).

Whatever those systems create is the mere semblance of intelligence and in pursuing the goal of generating artificial intelligence by imitation, we are following a cargo cult.

Instead, we should get comfortable with the fact that the current ways will not achieve real AI, and we should stop calling it that. Machine learning (ML) is a perfectly fitting term for a tool with awesome capabilities in the narrow fields where it can be applied. And with any tool, you should not try to make the entire world your nail, but instead find out where to use it and where not.

Machines are strong when it comes to quickly and repeatedly performing a task with minimal uncertainty. They are the ruling class of the first rung.

Humans are strong when it comes to context, understanding and making sense with very little data at hand and high uncertainties. They are the ruling class of the second and third rung.

So what if we focus our efforts away from the current obsession with removing the human element from everything and thought about combining both strengths? There is an enormous potential in giving machine learning systems the optimal, human-centric shape, in finding the right human-machine interface, so that both can shine. The ML system prepares the data, does some automatable tasks and then hands the results to the human, who further handles them according to context.

ML can become something like good staff to a CEO, a workhorse to a farmer or a good user interface to an app user: empowering, saving time, reducing mistakes.

Building a ML system for a given task is rather easy and will become ever easier. But finding a robust, working integration of the data and the pre-processed results of the data with the decision-maker (i.e. human) is a hard task. There is a reason why most ML projects fail at the stage of adoption/integration with the organization seeking to use them.

Solving this is a creative task: It is about domain understanding, product design and communication. Instead of going ever bigger to serve, say, more targetted ads, the true prize is in connecting data and humans in clever ways to make better decisions and be able to solve tougher and more important problems.

Republished with permission of the World Economic Forum. Read the original article.

• Despite being the only bridge early hominin species could have crossed to enter Eurasia, the Arabian Peninsula bears little to no evidence of early human occupation.
• Subverting expectations, a recent excavation in the Nefud Desert found tools dated to different stages of hominin evolution.
• It turns out that early humans moved in and out of the peninsula whenever the climate allowed them to do so.

We know a good deal about how early hominins †the branch of our evolutionary tree that split from chimps and bonobos up to seven million years ago †moved around their place of origin in eastern Africa. Fossils indicate they eventually made it to Eurasia through the Levant area of western Asia. This luscious green region, located on the easternmost edges of the Mediterranean, served our ancestors as the highway between two continents, one they would cross many times †in both directions.

Given how the Arabian Peninsula, a landmass that encapsulates the Levant, was our ancestors' one and only access point to the wider world, one would think evidence of their presence would stretch from Israel to Yemen. However, this is not the case. While the Levant is littered with prodigious digging sites, the paleontological and paleoenvironmental records of the peninsula's interior have remained hauntingly empty and fragmented.

That is, until today. According to a new paper published in Nature, excavations in the Nefud Desert in Saudi Arabia unearthed traces of both human and Neanderthal occupation. By shrinking their search window to wetter periods on the geologic time scale †what the authors refer to as "brief 'green' windows of reduced aridity approximately 400, 300, 200, 130-75 and 55 thousand years ago" †archaeologists were able to find a number of Low to Middle Pleistocene Age tools used by proto-humans that ventured into the region after heavy rainfall transformed the desert into a wide-open grassland.

Digging in the desert

To say the interior parts of the Arabian Peninsula have never yielded evidence of hominins would not be entirely true. The earth here hides evidence of hominins, just not of hominin settlements. Whenever archaeologists make a discovery, it is usually the remnants of a makeshift workshop site, which are very different from the cave and rock shelters that can be stumbled upon throughout the more hospitable Levant region. Did we look hard enough, though?

Excavations in northern Saudi Arabia at a site called Khall Amayshan 4 (KAM 4) suggest we did not. On the surface, the site looks like any other part of the Nefud Desert. Below ground, however, sedimentary rocks and interdunal basins tell of a time when this place used to contain a network of lakes and rivers. Such a clear and detailed preservation of this time in geologic history cannot be found anywhere else on the peninsula and was formed serendipitously when a sand dune slid atop the basin to protect it from erosion.

We know the shores at KAM 4 have been occupied by hominins several times during the Pleistocene because different phases of lake formation correspond with a "distinct lithic assemblage" †an archaeological term for stone tools and their byproducts, of which KAM 4 is filled to the brim. A 400,000-year-old assemblage contains small hand axes made from slabs of quartzite, while a 55,000-year-old deposit contains a number of Levallois flakes.

These tools can teach us several things about the hominins that made and used them. In terms of appearance and design, some assemblages at KAM 4 seem to have more in common with those found in Africa than those from the Levantine woodlands, suggesting a different migration out of Africa might have taken place †one that ended up in Arabia rather than Eurasia. "It seems," the researchers write, "that much of Northeast Africa and Southwest Asia shared similar material culture."

Climate change and migratory patterns

Hominin species did not hop continents at random; their migratory patterns were a response to the changing climate of the Pleistocene. Judging from the results of their excavation at KAM 4, researchers identified no less than five distinct movements into the Arabian Peninsula. Given that most of the tools were dated to periods that saw increased rainfall, it is safe to say our ancestors only migrated into the desert when it became hospitable enough for them to do so.

Conversely, researchers were unable to find any tools that would have been left during interglacial periods. It seems that, as the region became warmer and more arid, the hominin populations that had made their home inside the peninsula dispersed once again. The unstable environmental conditions that plagued the peninsula may well explain the fragmentation of its fossil evidence, a problem that researchers in the relatively static Levantine woodlands rarely encounter.

Because climate change and the accompanying mass migratory movements can actually erase the vast majority of a species' fossil record, these findings bear relevance to modern readers. This year's UN climate report warns of Arctic summers without ice and tropical storms that will become even more ubiquitous than they already are. What if hundreds of thousands of people have to leave their homes either temporarily or indefinitely?

• Concentrated solar thermal power is a fascinating technology.
• These plants can produce power after dark, unlike standard solar photovoltaic plants.
• Currently, they cost too much, but some innovative companies are forging ahead.

How mirrors could power the planet... and prevent wars | Hard Reset by Freethink

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Flying across the American Southwest, brilliant points of light shine in the distant wastes of the Mojave Desert. Three glowing spots hover over the horizon, each surrounded by a gleaming field. These are the towers and mirrors (heliostats) of the Ivanpah generating station, one of the largest concentrated solar power plants on Earth. What is this technology that allows solar power to continue at night, and how does it work?

Traditional photovoltaic (PV) solar cells absorb sunlight and pour out electricity. Particles of light (photons) emitted by the sun travel through space, transit Earth's atmosphere, and smack into a solar panel. Some photons are reflected away by the panel and lost. Most of them are absorbed by the atoms of the panel, which then release electrons. The solar cell's electrical design gathers these electrons and channels them out as electrical current. Further electrical devices convert this low voltage direct current (DC) to higher voltage alternating current (AC) to send across power transmission lines.

Concentrated solar thermal (CST) power plants do not directly exchange solar photons for electrons. They gather the photons and use them to heat water, which turns a steam turbine, which turns an electrical generator. This is the same way that nuclear fission and fossil fuel plants generate electricity †the difference being that uranium or coal or natural gas are replaced by the heat of the sun's rays.

The solar concentrator's basic design is simple. An array of heliostats †a term for mirrors on swiveling mounts capable of tracking the sun †is built on the ground. These arrays cover many hundreds of acres, roughly comparable to a large traditional solar plant of similar capacity. Each mirror is continuously adjusted so that it points in a direction that bisects the angle between the sun and a giant power tower. Sunlight is thus beamed up toward a boiler system looming 400-800 feet above the earth.

Approaching the central tower, the converging solar light from thousands of mirrors becomes extremely powerful. Visible from many miles away, the nearly transparent air itself will shine with scattered optical power. Unlucky birds that intersect the concentrated beams are incinerated mid-air. This dense power is what ultimately drives electrical generation.

The top of the tower is a box with black walls †the sides of a boiler designed to absorb nearly all of the reflected light, which contains the fluid to be heated. Some plants, like Ivanpah in California, heat water for their steam turbines. Others use a more exotic molten salt working fluid.

Solar thermal concentration offers one major advantage over traditional PV solar cell technology: dispatchability. A properly configured CST plant can broil molten salt to more than 1000 degrees Fahrenheit, storing an incredible amount of heat energy. The liquid salt is then pumped into a holding tank, acting as a sort of battery. When sunlight is not available (roughly half the time), this stored up sunlight energy can be pumped out of the tank and used to power a turbine generator for on-demand power overnight.

Installed CST electricity generation across the globe is relatively low. While the technology works today, and paths to advance it have been laid out, the cost is currently too high to compete with standard photovoltaic cells. Many nations, including Israel, the United Arab Emirates, Morocco, China, Chile, Spain, and India have built giant power tower installations, yet most of their future commitments are unclear. While concentrated solar thermal power has been growing cheaper, PV cell cost has been dropping just as rapidly.

The future of this energy source may well hinge on continued development of its stored energy capability for dispatchable power, which is needed to fill in for inconsistent wind turbines and PV solar plants.

Options today to store energy are very limited. Lithium-ion technology has many downsides that prevent countries from running on batteries. Like the cells in a laptop, they are expensive, they degrade dramatically over time, and they are liable to catch fire. Global production capacity is far too small for the task, and that production is dominated by China.

Concentrated solar thermal technology is straightforward and clean. The design is beautiful and still being improved. Effectively storing sunlight for overnight power dispatch is a brilliant feature. Still, commercial grid electricity is a brutal market in which the cheapest wins. Will solar concentrator plants become competitive and multiply around the world? We shall see.

In recent decades the cost of wind and solar power generation has dropped dramatically.

This is one reason that the U.S. Department of Energy projects that renewable energy will be the
fastest-growing U.S. energy source through 2050.

However, it's still relatively expensive to store energy. And since renewable energy generation
isn't available all the time – it happens when the wind blows or the sun shines – storage is essential.

As a
researcher at the National Renewable Energy Laboratory, I work with the federal government and private industry to develop renewable energy storage technologies. In a recent report, researchers at NREL estimated that the potential exists to increase U.S. renewable energy storage capacity by as much as 3,000% percent by 2050.

Here are three emerging technologies that could help make this happen.

Longer charges

From alkaline batteries for small electronics to lithium-ion batteries for cars and laptops, most people already use batteries in many aspects of their daily lives. But there is still lots of room for growth.

For example, high-capacity batteries with long discharge times – up to 10 hours – could be valuable for storing solar power at night or increasing the range of electric vehicles. Right now there are very few such batteries in use. However, according to
recent projections, upwards of 100 gigawatts' worth of these batteries will likely be installed by 2050. For comparison, that's 50 times the generating capacity of Hoover Dam. This could have a major impact on the viability of renewable energy.

Batteries work by creating a chemical reaction that produces a flow of electrical current.

One of the biggest obstacles is limited supplies of lithium and cobalt, which currently are essential for making lightweight, powerful batteries. According to
some estimates, around 10% of the world's lithium and nearly all of the world's cobalt reserves will be depleted by 2050.

Furthermore, nearly 70% of the world's cobalt is mined in the Congo, under conditions that have long been documented as
inhumane.

Scientists are working to develop techniques for
recycling lithium and cobalt batteries, and to design batteries based on other materials. Tesla plans to produce cobalt-free batteries within the next few years. Others aim to replace lithium with sodium, which has properties very similar to lithium's but is much more abundant.

Safer batteries

Another priority is to make batteries safer. One area for improvement is electrolytes – the medium, often liquid, that
allows an electric charge to flow from the battery's anode, or negative terminal, to the cathode, or positive terminal.

When a battery is in use, charged particles in the electrolyte move around to balance out the charge of the electricity flowing out of the battery. Electrolytes often contain flammable materials. If they leak, the battery can overheat and catch fire or melt.

Scientists are developing solid electrolytes, which would make batteries more robust. It is much harder for particles to move around through solids than through liquids, but
encouraging lab-scale results suggest that these batteries could be ready for use in electric vehicles in the coming years, with target dates for commercialization as early as 2026.

While solid-state batteries would be well suited for consumer electronics and electric vehicles, for large-scale energy storage, scientists are pursuing all-liquid designs called
flow batteries.

A typical flow battery consists of two tanks of liquids that are pumped past a membrane held between two electrodes. (
Qi and Koenig, 2017, CC BY)

In these devices both the electrolyte and the electrodes are liquids. This allows for super-fast charging and makes it easy to make really big batteries. Currently these systems are very expensive, but research continues to
bring down the price.

Storing sunlight as heat

Other renewable energy storage solutions cost less than batteries in some cases. For example,
concentrated solar power plants use mirrors to concentrate sunlight, which heats up hundreds or thousands of tons of salt until it melts. This molten salt then is used to drive an electric generator, much as coal or nuclear power is used to heat steam and drive a generator in traditional plants.

These heated materials can also be stored to produce electricity when it is cloudy, or even at night. This approach allows concentrated solar power to work around the clock.

Checking a molten salt valve for corrosion at Sandia's Molten Salt Test Loop. (
Randy Montoya, Sandia Labs/Flickr, CC BY-NC-ND)

This idea could be adapted for use with nonsolar power generation technologies. For example, electricity made with wind power could be used to heat salt for use later when it isn't windy.

Concentrating solar power is still relatively expensive. To compete with other forms of energy generation and storage, it needs to become more efficient. One way to achieve this is to increase the temperature the salt is heated to, enabling more efficient electricity production. Unfortunately, the salts currently in use aren't stable at high temperatures. Researchers are working to develop new salts or other materials that can withstand temperatures as high as 1,300 degrees Fahrenheit (705 C).

One leading idea for how to reach higher temperature involves heating up sand instead of salt, which can withstand the higher temperature. The sand would then be moved with conveyor belts from the heating point to storage. The Department of Energy recently announced funding for a
pilot concentrated solar power plant based on this concept.

Advanced renewable fuels

Batteries are useful for short-term energy storage, and concentrated solar power plants could help stabilize the electric grid. However, utilities also need to store a lot of energy for indefinite amounts of time. This is a role for renewable fuels like
hydrogen and ammonia. Utilities would store energy in these fuels by producing them with surplus power, when wind turbines and solar panels are generating more electricity than the utilities' customers need.

Hydrogen and ammonia contain more energy per pound than batteries, so they work where batteries don't. For example, they could be used
for shipping heavy loads and running heavy equipment, and for rocket fuel.

Today these fuels are mostly made from natural gas or other nonrenewable
fossil fuels via extremely inefficient reactions. While we think of it as a green fuel, most hydrogen gas today is made from natural gas.

Scientists are looking for ways to produce hydrogen and other fuels using renewable electricity. For example, it is possible to make hydrogen fuel by
splitting water molecules using electricity. The key challenge is optimizing the process to make it efficient and economical. The potential payoff is enormous: inexhaustible, completely renewable energy.

Kerry Rippy, Researcher, National Renewable Energy Laboratory

This article is republished from
The Conversation under a Creative Commons license. Read the original article.