New approach suggests path to emissions-free cement

It’s well known that the production of cement — the world’s leading construction material — is a major source of greenhouse gas emissions, accounting for about 8 percent of all such releases. If cement production were a country, it would be the world’s third-largest emitter.

A team of researchers at MIT has come up with a new way of manufacturing the material that could eliminate these emissions altogether, and could even make some other useful products in the process.

The findings are being reported today in the journal PNAS in a paper by Yet-Ming Chiang, the Kyocera Professor of Materials Science and Engineering at MIT, with postdoc Leah Ellis, graduate student Andres Badel, and others.

“About 1 kilogram of carbon dioxide is released for every kilogram of cement made today,” Chiang says. That adds up to 3 to 4 gigatons (billions of tons) of cement, and of carbon dioxide emissions, produced annually today, and that amount is projected to grow. The number of buildings worldwide is expected to double by 2060, which is equivalent to “building one new New York City every 30 days,” he says. And the commodity is now very cheap to produce: It costs only about 13 cents per kilogram, which he says makes it cheaper than bottled water.

So it’s a real challenge to find ways of reducing the material’s carbon emissions without making it too expensive. Chiang and his team have spent the last year searching for alternative approaches, and hit on the idea of using an electrochemical process to replace the current fossil-fuel-dependent system.

Ordinary Portland cement, the most widely used standard variety, is made by grinding up limestone and then cooking it with sand and clay at high heat, which is produced by burning coal. The process produces carbon dioxide in two different ways: from the burning of the coal, and from gases released from the limestone during the heating. Each of these produces roughly equal contributions to the total emissions. The new process would eliminate or drastically reduce both sources, Chiang says. Though they have demonstrated the basic electrochemical process in the lab, the process will require more work to scale up to industrial scale.

First of all, the new approach could eliminate the use of fossil fuels for the heating process, substituting electricity generated from clean, renewable sources. “In many geographies renewable electricity is the lowest-cost electricity we have today, and its cost is still dropping,” Chiang says. In addition, the new process produces the same cement product. The team realized that trying to gain acceptance for a new type of cement — something that many research groups have pursued in different ways — would be an uphill battle, considering how widely used the material is around the world and how reluctant builders can be to try new, relatively untested materials.

The new process centers on the use of an electrolyzer, something that many people have encountered as part of high school chemistry classes, where a battery is hooked up to two electrodes in a glass of water, producing bubbles of oxygen from one electrode and bubbles of hydrogen from the other as the electricity splits the water molecules into their constituent atoms. Importantly, the electrolyzer’s oxygen-evolving electrode produces acid, while the hydrogen-evolving electrode produces a base.

In the new process, the pulverized limestone is dissolved in the acid at one electrode and high-purity carbon dioxide is released, while calcium hydroxide, generally known as lime, precipitates out as a solid at the other. The calcium hydroxide can then be processed in another step to produce the cement, which is mostly calcium silicate.

The carbon dioxide, in the form of a pure, concentrated stream, can then be easily sequestered, harnessed to produce value-added products such as a liquid fuel to replace gasoline, or used for applications such as oil recovery or even in carbonated beverages and dry ice. The result is that no carbon dioxide is released to the environment from the entire process, Chiang says. By contrast, the carbon dioxide emitted from conventional cement plants is highly contaminated with nitrogen oxides, sulfur oxides, carbon monoxide and other material that make it impractical to “scrub” to make the carbon dioxide usable.

Calculations show that the hydrogen and oxygen also emitted in the process could be recombined, for example in a fuel cell, or burned to produce enough energy to fuel the whole rest of the process, Ellis says, producing nothing but water vapor.

In a demonstration of the basic chemical reactions used in the new process, electrolysis takes place in neutral water. Dyes show how acid (pink) and base (purple) are produced at the positive and negative electrodes. A variation of this process can be used to convert calcium carbonate (CaCO3) into calcium hydroxide (Ca(OH)2), which can then be used to make Portland cement without producing any greenhouse gas emissions. Cement production currently causes 8 percent of global carbon emissions.

In their laboratory demonstration, the team carried out the key electrochemical steps required, producing lime from the calcium carbonate, but on a small scale. The process looks a bit like shaking a snow-globe, as it produces a flurry of suspended white particles inside the glass container as the lime precipitates out of the solution.

While the technology is simple and could, in principle, be easily scaled up, a typical cement plant today produces about 700,000 tons of the material per year. “How do you penetrate an industry like that and get a foot in the door?” asks Ellis, the paper’s lead author. One approach, she says, is to try to replace just one part of the process at a time, rather than the whole system at once, and “in a stepwise fashion” gradually add other parts.

The initial proposed system the team came up with is “not because we necessarily think we have the exact strategy” for the best possible approach, Chiang says, “but to get people in the electrochemical sector to start thinking more about this,” and come up with new ideas. “It’s an important first step, but not yet a fully developed solution.”

The research was partly supported by the Skolkovo Institute of Science and Technology.

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Global agreements

Many linguistics scholars regard the world’s languages as being fundamentally similar. Yes, the characters, words, and rules vary. But underneath it all, enough similar structures exist to form what MIT scholars call universal grammar, a capacity for language that all humans share.

To see how linguists find similariites that can elude the rest of us, consider a language operation called “allocutive agreement.” This is a variation of standard subject-verb agreement. Normally, a verb ending simply agrees with the subject of a sentence, so that in English we say, “You go,” but also, “She goes.”

Allocutive agreement throws a twist into this procedure: Even a third-person verb ending, such as “she goes,” changes depending on the social status of the person being spoken to. This happens in Basque, for one. It also occurs in Japanese, says MIT linguist Shigeru Miyagawa, even though Japanese has long been thought not to deploy agreement at all. But in fact, Miyagawa asserts, the same principles of formality appear in Japanese, if you know where to look.

“It goes a long way toward the idea that there’s agreement in every language,” says Miyagawa, a professor of linguistics and the Kochi-Manjiro Professor of Japanese Language and Culture at MIT. “In Japanese this politeness system has exactly the same distribution as the Basque allocutive system.”

Now Miyagawa has published a book — “Agreement Beyond Phi,” out today from the MIT Press — that explores some of these unexpected structural similarities among languages. The book has a second aim, as well: Miyagawa would like to orient the search for universal linguistic principles around a greater diversity of languages. (The title, incidentally, refers to agreement systems that are not found in Indo-European languages.)

Because English is the native language of so many great linguists, he observes, there is a tendency to regard it as a template for other languages. But drawing more heavily on additional languages, Miyagawa thinks, could lead to new insights about the specific contents of our universal language capacity; he cites the work of MIT linguist Norvin Richards as an example of this kind of work.

“Given the prominence of Indo-European languages, especially English, in linguistic theory, one sometimes gets the impression that if something happens in English it’s due to universal grammar, but if something happens in Japanese, it’s because it’s Japanese,” Miyagawa says.

Not mere formalities

To see why allocutive agreement seems like such a compelling example to Miyagawa, take a very brief look at how it works.

The best-known examples of addressing people formally come from Indo-European languages such as French, in which second-person subject-verb agreement changes in a simple way, depending on the social status of the person being addressed. Consider the phrase, “You speak.” To a peer or friend, you would use the informal version, “Tu parles.” But to a teacher or an older stranger you would likely use the more formal agreement, “Vous parlez.”

What happens in Basque and Japanese is a bit more complicated, however, since both informal and formal modes of address are employed even when speaking about other people. For instance, in Basque, consider a phrase Miyagawa dissects in the book, “Peter worked.” To a male friend, you would say, “Peter lan egin dik.” But to someone with higher social status, you would say, “Peter lan egin dizu.” The verb ending — the verb is last word in this sentence — changes even though it remains in the third person.

And while Japanese grammar differs in many ways from Basque grammar, Miyagawa contends in the new book that Japanese “politeness marking” follows the same rules. The sentence “Taro said that Hanako will come,” for example, includes the politeness marking “mas” when being spoken in a formal setting. In Japanese, transliterated in English characters, this becomes: “Taroo-wa hanako-ga ki-mas-u to itta.” But for the same sentence, when spoken to a peer, the “mas” disappears.

This kind of agreement, Miyagawa notes, is something he proposed in a 2010 book — titled, “Why Agree? Why Move?” — but did not observe until about 2012.

“I found in Basque the prediction I made in 2010 but couldn’t substantiate then,” Miyagawa says. “It’s exactly the same agreement system.”

Strikingly, Basque and Japanese seem to have very different origins. And Basque — although spoken in the Basque region that lies in between France and Spain — is not an Indo-European language. Indeed, linguists are not certain how to account for the origins of Basque. The presence of allocative agreement in both tongues, then, suggests a deep and unexpected universality among the kinds of linguistic rules that can occur.

Unpredictable

Miyagawa acknowledges he cannot predict precisely how his colleagues in linguistics will react to the book’s agenda, but says he has gotten a positive reception when presenting its concepts at conferences.

Certainly, some linguists have been very receptive to Miyagawa’s arguments. Johan Rooryck, a professor of French linguistics at Leiden University in the Netherlands, has said that Miyagawa’s new book “makes an elegant and compelling case for this exciting perspective.”

Miyagawa himself stresses that the point of the research is not to upend the conceptual foundations of universal grammar — as codified by MIT linguist Noam Chomsky and many others — but to expand the range of comparisons available to linguists. Beyond English, Japanese, and Basque, the book also draws on similarities found in Dinka (spoken in Sudan) and Jingpo (spoken in China and Burma), among other languages.

The book, he says, “is heavily influenced by the insights of the previous work, [and is] standing on the shoulders of some of the great minds, of Chomsky and many others.”

But when linguists look at more and more languages, Miyagawa adds, “You start to discover things you never noticed before.”

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Low Emission Development Strategies around the World: Linking climate action and sustainable development based on the experience of two EU-funded projects – 27 September 2019, Brussels, Belgium

[Source: Research & Innovation] This conference will bring together stakeholders, policy experts and two ground-breaking EU-funded projects that have been working in this area to present the project results and discuss implications for climate, energy and development policies.
CD-LINKS is a H2020 project focused on linking climate and development policies. It has brought together leading institutes from G20 countries and beyond to improve the global knowledge base, strengthen the global research network and reinforce each country’s capacity to build global and national low emission pathways.
Africa-LEDS has been working with 7 African countries on Low Emission Development Strategies. It focuses on working with policymakers to demonstrate how NDC implementation can contribute to socioeconomic priorities.Venue: Borschette Conference Centre (Room 3A), Brussels Source

Events – Horizon Europe Lunch Workshop – European Health Forum Gastein 2019 – 3 October 2019, Bad Hofgastein, Austria

The Commission is preparing Horizon Europe, the next and most ambitious EU research and innovation programme (2021-2027) with a proposed budget of €100 billion, in an intensive codesign process. The co-design process ensures that Horizon Europe is directed towards what matters most, improves our daily lives and helps turn big societal challenges into innovation opportunities and solutions for a sustainable future.

By bringing together speakers from the EHFGs ‘four pillars’ and drawing on the Forum’s expert participants from health and other relevant sectors and stakeholder groups, an interactive, outcomes-oriented session will be shaped. DG RTD will showcase the outcomes of the co-design process (focusing on the Health-related impacts), to reach a full range of stakeholders and gather feedback on the projected direction of the Horizon Europe.

Maggie DE BLOCK, Minister of Social Affairs and Public Health, and Asylum and Migration, Belgium, Belgium

Irene NORSTEDT, Director of People Directorate (health and social sciences), Directorate-General for Research and Innovation (DG RTD), European Commission

Fiona GODFREY, Secretary General, European Public Health Alliance

Nathalie MOLL, Director-General, European Federation of Pharmaceutical Industries and Associations (EFPIA) (tbc)

Moderated by Nick FAHY, Senior Researcher, Medical Sciences Division, University of Oxford

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MIT engineers develop “blackest black” material to date

With apologies to “Spinal Tap,” it appears that black can, indeed, get more black.

MIT engineers report today that they have cooked up a material that is 10 times blacker than anything that has previously been reported. The material is made from vertically aligned carbon nanotubes, or CNTs — microscopic filaments of carbon, like a fuzzy forest of tiny trees, that the team grew on a surface of chlorine-etched aluminum foil. The foil captures at least 99.995 percent* of any incoming light, making it the blackest material on record.

The researchers have published their findings today in the journal ACS-Applied Materials and Interfaces. They are also showcasing the cloak-like material as part of a new exhibit today at the New York Stock Exchange, titled “The Redemption of Vanity.”

The artwork, a collaboration between Brian Wardle, professor of aeronautics and astronautics at MIT, and his group, and MIT Center for Art, Science, and Technology artist-in-residence Diemut Strebe, features a 16.78-carat natural yellow diamond from LJ West Diamonds, estimated to be worth $2 million, which the team coated with the new, ultrablack CNT material. The effect is arresting: The gem, normally brilliantly faceted, appears as a flat, black void.

Wardle says the CNT material, aside from making an artistic statement, may also be of practical use, for instance in optical blinders that reduce unwanted glare, to help space telescopes spot orbiting exoplanets.

“There are optical and space science applications for very black materials, and of course, artists have been interested in black, going back well before the Renaissance,” Wardle says. “Our material is 10 times blacker than anything that’s ever been reported, but I think the blackest black is a constantly moving target. Someone will find a blacker material, and eventually we’ll understand all the underlying mechanisms, and will be able to properly engineer the ultimate black.”

Wardle’s co-author on the paper is former MIT postdoc Kehang Cui, now a professor at Shanghai Jiao Tong University.

Into the void

Wardle and Cui didn’t intend to engineer an ultrablack material. Instead, they were experimenting with ways to grow carbon nanotubes on electrically conducting materials such as aluminum, to boost their electrical and thermal properties.

But in attempting to grow CNTs on aluminum, Cui ran up against a barrier, literally: an ever-present layer of oxide that coats aluminum when it is exposed to air. This oxide layer acts as an insulator, blocking rather than conducting electricity and heat. As he cast about for ways to remove aluminum’s oxide layer, Cui found a solution in salt, or sodium chloride.

At the time, Wardle’s group was using salt and other pantry products, such as baking soda and detergent, to grow carbon nanotubes. In their tests with salt, Cui noticed that chloride ions were eating away at aluminum’s surface and dissolving its oxide layer.

“This etching process is common for many metals,” Cui says. “For instance, ships suffer from corrosion of chlorine-based ocean water. Now we’re using this process to our advantage.”

Cui found that if he soaked aluminum foil in saltwater, he could remove the oxide layer. He then transferred the foil to an oxygen-free environment to prevent reoxidation, and finally, placed the etched aluminum in an oven, where the group carried out techniques to grow carbon nanotubes via a process called chemical vapor deposition.

By removing the oxide layer, the researchers were able to grow carbon nanotubes on aluminum, at much lower temperatures than they otherwise would, by about 100 degrees Celsius. They also saw that the combination of CNTs on aluminum significantly enhanced the material’s thermal and electrical properties — a finding that they expected.

What surprised them was the material’s color.

“I remember noticing how black it was before growing carbon nanotubes on it, and then after growth, it looked even darker,” Cui recalls. “So I thought I should measure the optical reflectance of the sample.

“Our group does not usually focus on optical properties of materials, but this work was going on at the same time as our art-science collaborations with Diemut, so art influenced science in this case,” says Wardle.

Wardle and Cui, who have applied for a patent on the technology, are making the new CNT process freely available to any artist to use for a noncommercial art project.

“Built to take abuse”

Cui measured the amount of light reflected by the material, not just from directly overhead, but also from every other possible angle. The results showed that the material absorbed at least 99.995 percent of incoming light, from every angle. In other words, it reflected 10 times less light than all other superblack materials, including Vantablack. If the material contained bumps or ridges, or features of any kind, no matter what angle it was viewed from, these features would be invisible, obscured in a void of black.  

The researchers aren’t entirely sure of the mechanism contributing to the material’s opacity, but they suspect that it may have something to do with the combination of etched aluminum, which is somewhat blackened, with the carbon nanotubes. Scientists believe that forests of carbon nanotubes can trap and convert most incoming light to heat, reflecting very little of it back out as light, thereby giving CNTs a particularly black shade.

“CNT forests of different varieties are known to be extremely black, but there is a lack of mechanistic understanding as to why this material is the blackest. That needs further study,” Wardle says.

The material is already gaining interest in the aerospace community. Astrophysicist and Nobel laureate John Mather, who was not involved in the research, is exploring the possibility of using Wardle’s material as the basis for a star shade — a massive black shade that would shield a space telescope from stray light.

“Optical instruments like cameras and telescopes have to get rid of unwanted glare, so you can see what you want to see,” Mather says. “Would you like to see an Earth orbiting another star? We need something very black. … And this black has to be tough to withstand a rocket launch. Old versions were fragile forests of fur, but these are more like pot scrubbers — built to take abuse.”

*An earlier version of this story stated that the new material captures more than 99.96 percent of incoming light. That number has been updated to be more precise; the material absorbs at least 99.995 of incoming light.

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Articles of faith

If you have the chance, listen to a toddler use the words “a” and “the” before a noun. Can you detect a pattern? Is he or she using those two words correctly?

And one more question: When kids start using language, how much of their know-how is intrinsic, and how much is acquired by listening to others speak?

Now a study co-authored by an MIT professor uses a new approach to shed more light on this matter — a central issue in the area of language acquisition.

The results suggest that experience is an important component of early-childhood language usage although it doesn’t necessarily account for all of a child’s language facility. Moreover, the extent to which a child learns grammar by listening appears to change over time, with a large increase occurring around age 2 and a leveling off taking place in subsequent years.

“In this view, adult-like, rule-based [linguistic] development is the end-product of a construction of knowledge,” says Roger Levy, an MIT professor and co-author of a new paper summarizing the study. Or, as the paper states, the findings are consistent with the idea that children “lack rich grammatical knowledge at the outset of language learning but rapidly begin to generalize on the basis of structural regularities in their input.”

The paper, “The Emergence of an Abstract Grammatical Category in Children’s Early Speech,” appears in the latest issue of Psychological Science. The authors are Levy, a professor in MIT’s Department of Brain and Cognitive Sciences; Stephan Meylann of the University of California at Berkeley; Michael Frank of Stanford University; and Brandon Roy of Stanford and the MIT Media Lab.

Learning curve

Studying how children use terms such as “a dog” or “the dog” correctly can be a productive approach to language acquisition, since children use the articles “a” and “the” relatively early in their lives and tend to use them correctly. Again, though: Is that understanding of grammar innate or acquired?

Some previous studies have examined this specific question by using an “overlap score,” that is, the proportion of nouns that children use with both “a” and “the,” out of all the nouns they use. When children use both terms correctly, it indicates they understand the grammatical difference between indefinite and definite articles, as opposed to cases where they may (incorrectly) think only one or the other is assigned to a particular noun.

One potential drawback to this approach, however, is that the overlap score might change over time simply because a child might hear more article-noun pairings, without fully recognizing the grammatical distinction between articles.

By contrast, the current study builds a statistical model of language use that incorporates not only child language use but adult language use recorded around children, from a variety of sources. Some of these are publicly available copora of recordings of children and caregivers; others are records of individual children; and one source is the “Speechome” experiment conducted by Deb Roy of the MIT Media Lab, which features recordings of over 70 percent of his child’s waking hours.

The Speechome data, as the paper notes, provides some of the strongest evidence yet that “children’s syntactic productivity changes over development” — that younger children learn grammar from hearing it, and do so at different rates during different phases of early childhood.

“I think the method starts to get us traction on the problem,” Levy says. “We saw this as an opportunity both to use more comprehensive data and to develop new analytic techniques.”

A work in progress

Still, as the authors note, a second conclusion of the paper is that more basic data about language development is needed. As the paper notes, much of the available information is not comprehensive enough, and thus “likely not sufficient to yield precise developmental conclusions.”

And as Levy readily acknowledges, developing an airtight hypothesis about grammar acquisition is always likely to be a challenge.

“We’re never going to have an absolute complete record of everything a child has ever heard,” Levy says.

That makes it much harder to interpret the cognitive process leading to either correct or incorrect uses of, say, articles such as “a” and “the.” After all, if a child uses the phrase “a bus” correctly, it still might only be because that child has heard the phrase before and likes the way it sounds, not because he or she grasped the underlying grammar.

“Those things are very hard to tease apart, but that’s what we’re trying to do,” Levy says. “This is only really an initial step.”

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Scientists detect tones in the ringing of a newborn black hole for the first time

If Albert Einstein’s theory of general relativity holds true, then a black hole, born from the cosmically quaking collisions of two massive black holes, should itself “ring” in the aftermath, producing gravitational waves much like a struck bell reverbates sound waves. Einstein predicted that the particular pitch and decay of these gravitational waves should be a direct signature of the newly formed black hole’s mass and spin.

Now, physicists from MIT and elsewhere have studied the ringing of an infant black hole, and found that the pattern of this ringing does, in fact, predict the black hole’s mass and spin — more evidence that Einstein was right all along.

The findings, published today in Physical Review Letters, also favor the idea that black holes lack any sort of “hair” — a metaphor referring to the idea that black holes, according to Einstein’s theory, should exhibit just three observable properties: mass, spin, and electric charge. All other characteristics, which the physicist John Wheeler termed “hair,” should be swallowed up by the black hole itself, and would therefore be unobservable.

The team’s findings today support the idea that black holes are, in fact, hairless. The researchers were able to identify the pattern of a black hole’s ringing, and, using Einstein’s equations, calculated the mass and spin that the black hole should have, given its ringing pattern. These calculations matched measurements of the black hole’s mass and spin made previously by others.

If the team’s calculations deviated significantly from the measurements, it would have suggested that the black hole’s ringing encodes properties other than mass, spin, and electric charge — tantalizing evidence of physics beyond what Einstein’s theory can explain. But as it turns out, the black hole’s ringing pattern is a direct signature of its mass and spin, giving support to the notion that black holes are bald-faced giants, lacking any extraneous, hair-like properties.

“We all expect general relativity to be correct, but this is the first time we have confirmed it in this way,” says the study’s lead author, Maximiliano Isi, a NASA Einstein Fellow in MIT’s Kavli Institute for Astrophysics and Space Research. “This is the first experimental measurement that succeeds in directly testing the no-hair theorem. It doesn’t mean black holes couldn’t have hair. It means the picture of black holes with no hair lives for one more day.”

A chirp, decoded

On Sept. 14, 2015, scientists made the first-ever detection of gravitational waves — infinitesimal ripples in space-time, emanating from distant, violent cosmic phenomena. The detection, named GW150914, was made by LIGO, the Laser Interferometer Gravitational-wave Observatory. Once scientists cleared away the noise and zoomed in on the signal, they observed a waveform that quickly crescendoed before fading away. When they translated the signal into sound, they heard something resembling a “chirp.”

Scientists determined that the gravitational waves were set off by the rapid inspiraling of two massive black holes. The peak of the signal — the loudest part of the chirp — linked to the very moment when the black holes collided, merging into a single, new black hole. While this infant black hole gave off gravitational waves of its own, its signature ringing, physicists assumed, would be too faint to decipher amid the clamor of the initial collision. Thus, traces of this ringing were only identified some time after the peak, where the signal was too faint to study in detail.

Isi and his colleagues, however, found a way to extract the black hole’s reverberation from the moments immediately after the signal’s peak. In previous work led by Isi’s co-author, Matthew Giesler of Caltech, the team showed through simulations that such a signal, and particularly the portion right after the peak, contains “overtones” — a family of loud, short-lived tones. When they reanalyzed the signal, taking overtones into account, the researchers discovered that they could successfully isolate a ringing pattern that was specific to a newly formed black hole.

In the team’s new paper, the researchers applied this technique to actual data from the GW150914 detection, concentrating on the last few milliseconds of the signal, immediately following the chirp’s peak. Taking into account the signal’s overtones, they were able to discern a ringing coming from the new, infant black hole. Specifically, they identified two distinct tones, each with a pitch and decay rate that they were able to measure.

“We detect an overall gravitational wave signal that’s made up of multiple frequencies, which fade away at different rates, like the different pitches that make up a sound,” Isi says. “Each frequency or tone corresponds to a vibrational frequency of the new black hole.”

Listening beyond Einstein

Einstein’s theory of general relativity predicts that the pitch and decay of a black hole’s gravitational waves should be a direct product of its mass and spin. That is, a black hole of a given mass and spin can only produce tones of a certain pitch and decay. As a test of Einstein’s theory, the team used the equations of general relativity to calculate the newly formed black hole’s mass and spin, given the pitch and decay of the two tones they detected.

They found their calculations matched with measurements of the black hole’s mass and spin previously made by others. Isi says the results demonstrate that researchers can, in fact, use the very loudest, most detectable parts of a gravitational wave signal to discern a new black hole’s ringing, where before, scientists assumed that this ringing could only be detected within the much fainter end of the gravitational wave signal, and identifying many tones would require much more sensitive instruments than what currently exist.

“This is exciting for the community because it shows these kinds of studies are possible now, not in 20 years,” Isi says.

As LIGO improves its resolution, and more sensitive instruments come online in the future, researchers will be able to use the group’s methods to “hear” the ringing of other newly born black holes. And if they happen to pick up tones that don’t quite match up with Einstein’s predictions, that could be an even more exciting prospect.

“In the future, we’ll have better detectors on Earth and in space, and will be able to see not just two, but tens of modes, and pin down their properties precisely,” Isi says. “If these are not black holes as Einstein predicts, if they are more exotic objects like wormholes or boson stars, they may not ring in the same way, and we’ll have a chance of seeing them.”

This research was supported, in part, by NASA, the Sherman Fairchild Foundation, the Simons Foundation, and the National Science Foundation.

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