The largest paper ever published on radar observations of near-Earth asteroids has been released, compiling years’ worth of data from the Arecibo Observatory in Puerto Rico.
Using delay-Doppler radar observations collected from the observatory between December 2017 and December 2019, the study includes 191 asteroids’ radar cross sections and Doppler-frequency broadening. This data can be used as clues to asteroids’ spin periods and sizes, as well as polarization information for 110 of them, which could help to understand the surface and subsurface properties. Thirty-seven asteroids were presented in greater detail with more refined size evaluation, preliminary shape evaluation, information about how reflective they are in radar, and if the radar observations match with the visual and near-infrared observations.
The work was published recently in the Planetary Sciences Journal.
As one of the only papers of its kind that includes a large number of asteroid targets, the study serves as a “treasure trove of data” for planetary scientists given that most existing literature only focuses on one object at a time, says Anne Virkki, the study’s lead author and a researcher with the Department of Physics at the University of Helsinki in Finland.
The study’s ample amount of asteroid data is important for many reasons, the researchers say.
For instance, the characteristics of several potentially hazardous asteroids are included in the paper, which is notable because observations from Arecibo have contributed to past planetary defense efforts, including the recent DART mission.
Although Arecibo’s planetary radar group focuses on supporting NASA’s planetary defense program, the study’s wealth of information has economic benefits as well, supplying asteroid mining companies with data on metal-rich and ice-rich near-Earth asteroids containing resources of interest.
The diversity of asteroid data in general also clues other scientists in on the formation and evolution of the solar system.
Radar is the best ground-based tool for near-Earth asteroid characterization, says Flaviane Venditti, head of Arecibo’s Planetary Radar Science Group and study co-author.
“The amount of valuable data collected is unique, and these results could not have been achieved with any other existing facility,” Venditti says.
Though the telescope collapsed in 2020, scientists continue to analyze the backlog of data gathered from it.
Through the study, scientists found two near-Earth asteroids with abnormally high radar albedos, or reflectivity in radar, suggesting that they could be metal-rich. The possibility of two more is significant; few metal-rich NEAs have been found so far.
Another high radar albedos near-Earth asteroid, rare equal-mass binary 2017 YE5, was suggested to have ice below its surface instead of metal richness due to its low bulk density. Classified in the study as a D-type NEA, 2017 YE5 is potentially the first of its kind observed using radar.
More classifications were made with scientists listing five possible enstatite-rich, or E-type, asteroids that had not been identified as such previously, using polarization information from radar.
Accompanying the data were numerous 7.5m resolution asteroid images, a feature uncommon in existing literature. No other ground-based instrument than radar can take images at a resolution finer than 10m of any celestial objects further than the moon, and until the telescope’s collapse in 2020, the Arecibo radar was the most powerful and sensitive planetary radar in the world.
Though plentiful in its data, the study leaves doors open for further research.
“This paper is like a teaser for a full movie,” Virkki says.
Venditti says the data from the research shows how rich the information obtained with radar is.
“In fact, there’s still a lot of high-quality data to be analyzed in detail, which could even support planning future spacecraft missions to small bodies,” Venditti says.
Funding for the research was provided through NASA’s Near-Earth Object Observations program. The University of Central Florida manages the Arecibo Observatory for the U.S. National Science Foundation under a cooperative agreement.
Study title: Arecibo Planetary Radar Observations of Near-Earth Asteroids: 2017 December–2019 December
Virkki received her doctorate in astronomy from the University of Helsinki in 2016. She currently works at the University of Helsinki in the planetary science research group. Virkki joined the Arecibo Observatory in April 2016 and the University of Central Florida in April 2018. She served as head of Arecibo’s Planetary Radar Science Group from 2018 to 2021.
Venditti received her doctorate in space engineering at the National Institute for Space Research in Brazil in 2013. She joined Arecibo Observatory in 2017 and has served as head of its Planetary Radar Science Group since 2021.
Other Arecibo planetary radar members who contributed to the study include observatory scientists Sean Marshall and Maxime Devogèle, and data analysts Luisa Zambrano-Marín and Anna McGilvray.
Scientists build ‘baby’ wormhole as sci-fi moves closer to fact
WASHINGTON — In science fiction – think films and TV like “Interstellar” and “Star Trek” – wormholes in the cosmos serve as portals through space and time for spacecraft to traverse unimaginable distances with ease. If only it were that simple.
Scientists have long pursued a deeper understanding of wormholes and now appear to be making progress. Researchers announced on Wednesday that they forged two miniscule simulated black holes – those extraordinarily dense celestial objects with gravity so powerful that not even light can escape – in a quantum computer and transmitted a message between them through what amounted to a tunnel in space-time.
It was a “baby wormhole,” according to Caltech physicist Maria Spiropulu, a co-author of the research published in the journal Nature. But scientists are a long way from being able to send people or other living beings through such a portal, she said.
“Experimentally, for me, I will tell you that it’s very, very far away. People come to me and they ask me, ‘Can you put your dog in the wormhole?’ So, no,” Spiropulu told reporters during a video briefing. .”..That’s a huge leap.”
“There’s a difference between something being possible in principle and possible in reality,” added physicist and study co-author Joseph Lykken of Fermilab, America’s particle physics and accelerator laboratory. “So don’t hold your breath about sending your dog through the wormhole. But you have to start somewhere. And I think to me it’s just exciting that we’re able to get our hands on this at all.”
The researchers observed the wormhole dynamics on a quantum device at Alphabet’s Google called the Sycamore quantum processor.
A wormhole – a rupture in space and time – is considered a bridge between two remote regions in the universe. Scientists refer to them as Einstein–Rosen bridges after the two physicists who described them – Albert Einstein and Nathan Rosen.
Such wormholes are consistent with Einstein’s theory of general relativity, which focuses on gravity, one of the fundamental forces in the universe. The term “wormhole” was coined by physicist John Wheeler in the 1950s.
Spiropulu said the researchers found a quantum system that exhibits key properties of a gravitational wormhole but was small enough to implement on existing quantum hardware.
“It looks like a duck, it walks like a duck, it quacks like a duck. So that’s what we can say at this point – that we have something that in terms of the properties we look at, it looks like a wormhole,” Lykken said.
The researchers said no rupture of space and time was created in physical space in the experiment, though a traversable wormhole appeared to have emerged based on quantum information teleported using quantum codes on the quantum processor.
“These ideas have been around for a long time and they’re very powerful ideas,” Lykken said.
“But in the end, we’re in experimental science, and we’ve been struggling now for a very long time to find a way to explore these ideas in the laboratory. And that’s what’s really exciting about this. It’s not just, ‘Well, wormholes are cool.’ This is a way to actually look at these very fundamental problems of our universe in a laboratory setting.” (Reporting by Will Dunham, Editing by Rosalba O’Brien)
Supermassive Black Hole Violently Rips Star Apart, Launches Relativistic Jet Toward Earth
Several things happen, according to University of Maryland (UMD) astronomer Igor Andreoni: first, the star is violently ripped apart by the black hole’s gravitational tidal forces—similar to how the Moon pulls tides on Earth but with greater strength. Next, pieces of the star are captured into a swiftly spinning disk orbiting the black hole. Finally, the black hole consumes what remains of the doomed star in the disk. This is what astronomers call a tidal disruption event (TDE).
However, in some extremely rare cases, the supermassive black hole launches “relativistic jets” after destroying a star. These are beams of matter traveling close to the speed of light. Andreoni discovered one such case with his team in the Zwicky Transient Facility (ZTF) survey in February 2022. After the group publicly announced the sighting, the event was named “AT 2022cmc.” The team published its findings on November 30, 2022, in the journal Nature.
“The last time scientists discovered one of these jets was well over a decade ago,” said Michael Coughlin, an assistant professor of astronomy at the University of Minnesota Twin Cities and co-lead on the project. “From the data we have, we can estimate that relativistic jets are launched in only 1% of these destructive events, making AT 2022cmc an extremely rare occurrence. In fact, the luminous flash from the event is among the brightest ever observed.”
Before AT 2022cmc, the only two previously known jetted TDEs were discovered through gamma-ray space missions, which detect the highest-energy forms of radiation produced by these jets. As the last such discovery was made in 2012, new methods were required to find more events of this nature. To help address that need, Andreoni, who is a postdoctoral associate in the Department of Astronomy at UMD and <span class=”glossaryLink” aria-describedby=”tt” data-cmtooltip=”
” data-gt-translate-attributes=”[“attribute”:”data-cmtooltip”, “format”:”html”]”>NASA Goddard Space Flight Center, and his team implemented a novel, “big picture” tactic to find AT 2022cmc. They used ground-based optical surveys, or general maps of the sky without specific observational targets. Using ZTF, a wide-field sky survey taken by the Samuel Oschin Telescope in California, the team was able to identify and uniquely study the otherwise dormant-looking black hole.
“We developed an open-source data pipeline to store and mine important information from the ZTF survey and alert us about atypical events in real-time,” Andreoni explained. “The rapid analysis of ZTF data, the equivalent to a million pages of information every night, allowed us to quickly identify the TDE with relativistic jets and make follow-up observations that revealed an exceptionally high luminosity across the electromagnetic spectrum, from the X-rays to the millimeter and radio.”
Follow-up observations with many observatories confirmed that AT 2022cmc was fading rapidly and the ESO Very Large Telescope revealed that AT 2022cmc was at cosmological distance, 8.5 billion light years away.
<span class=”glossaryLink” aria-describedby=”tt” data-cmtooltip=”
” data-gt-translate-attributes=”[“attribute”:”data-cmtooltip”, “format”:”html”]”>Hubble Space Telescope optical/infrared images and radio observations from the Very Large Array pinpointed the location of AT 2022cmc with extreme precision. The researchers believe that AT 2022cmc was at the center of a galaxy that is not yet visible because the light from AT 2022cmc outshone it, but future space observations with Hubble or James Webb Space Telescopes may unveil the galaxy when the transient eventually disappears.
It is still a mystery why some TDEs launch jets while others do not seem to. From their observations, Andreoni and his team concluded that the black holes in AT 2022cmc and other similarly jetted TDEs are likely spinning rapidly so as to power the extremely luminous jets. This suggests that a rapid black hole spin may be one necessary ingredient for jet launching—an idea that brings researchers closer to understanding the physics of supermassive black holes at the center of galaxies billions of light years away.
“Astronomy is changing rapidly,” Andreoni said. “More optical and infrared all-sky surveys are now active or will soon come online. Scientists can use AT 2022cmc as a model for what to look for and find more disruptive events from distant black holes. This means that more than ever, big data mining is an important tool to advance our knowledge of the universe.”
Reference: “A very luminous jet from the disruption of a star by a massive black hole” by Igor Andreoni, Michael W. Coughlin, Daniel A. Perley, Yuhan Yao, Wenbin Lu, S. Bradley Cenko, Harsh Kumar, Shreya Anand, Anna Y. Q. Ho, Mansi M. Kasliwal, Antonio de Ugarte Postigo, Ana Sagués-Carracedo, Steve Schulze, D. Alexander Kann, S. R. Kulkarni, Jesper Sollerman, Nial Tanvir, Armin Rest, Luca Izzo, Jean J. Somalwar, David L. Kaplan, Tomás Ahumada, G. C. Anupama, Katie Auchettl, Sudhanshu Barway, Eric C. Bellm, Varun Bhalerao, Joshua S. Bloom, Michael Bremer, Mattia Bulla, Eric Burns, Sergio Campana, Poonam Chandra, Panos Charalampopoulos, Jeff Cooke, Valerio D’Elia, Kaustav Kashyap Das, Dougal Dobie, José Feliciano Agüí Fernández, James Freeburn, Cristoffer Fremling, Suvi Gezari, Simon Goode, Matthew J. Graham, Erica Hammerstein, Viraj R. Karambelkar, Charles D. Kilpatrick, Erik C. Kool, Melanie Krips, Russ R. Laher, Giorgos Leloudas, Andrew Levan, Michael J. Lundquist, Ashish A. Mahabal, Michael S. Medford, M. Coleman Miller, Anais Möller, Kunal P. Mooley, A. J. Nayana, Guy Nir, Peter T. H. Pang, Emmy Paraskeva, Richard A. Perley, Glen Petitpas, Miika Pursiainen, Vikram Ravi, Ryan Ridden-Harper, Reed Riddle, Mickael Rigault, Antonio C. Rodriguez, Ben Rusholme, Yashvi Sharma, I. A. Smith, Robert D. Stein, Christina Thöne, Aaron Tohuvavohu, Frank Valdes, Jan van Roestel, Susanna D. Vergani, Qinan Wang and Jielai Zhang, 30 November 2022, Nature.
Other UMD collaborators include: adjunct associate professor of astronomy Brad Cenko; astronomy professor M. Coleman Miller; graduate student Erica Hammerstein and Tomas Ahumada (M.S. ’20, astronomy).
The research was supported by the National Science Foundation (Grant Nos. PHY-2010970 425, OAC-2117997, 1106171 and AST-1440341), Wenner-Gren Foundation, Swedish Research Council (Reg. No. 427 2020-03330), European Research Council (Grant No. 759194 432 – USNAC), VILLUM FONDEN (Grant No. 19054), the Netherlands Organization for Scientific Research, Spanish National Research Project (RTI2018-098104-J-I00), NASA (Award No. No. 80GSFC17M0002), the Knut and Alice Wallenberg Foundation (Dnr KAW 2018.0067), Heising-Simons Foundation (Grant No. 12540303), European Union Seventh Framework Programme (Grant No. 312430) Caltech, IPAC, the Weizmann Institute for Science, the Oskar Klein Center at Stockholm University, the <span class=”glossaryLink” aria-describedby=”tt” data-cmtooltip=”
” data-gt-translate-attributes=”[“attribute”:”data-cmtooltip”, “format”:”html”]”>University of Washington, Deutsches Elektronen-Synchrotron and Humboldt University, Los Alamos National Laboratories, the TANGO Consortium of Taiwan, the University of Wisconsin at Milwaukee and Lawrence Berkeley National Laboratories.
Physicists Create ‘the Smallest, Crummiest Wormhole You Can Imagine’ – The New York Times
In an experiment that ticks most of the mystery boxes in modern physics, a group of researchers announced on Wednesday that they had simulated a pair of black holes in a quantum computer and sent a message between them through a shortcut in space-time called a wormhole.
Physicists described the achievement as another small step in the effort to understand the relation between gravity, which shapes the universe, and quantum mechanics, which governs the subatomic realm of particles.
“This is important because what we have here in its construct and structure is a baby wormhole,” said Maria Spiropulu, a physicist at the California Institute of Technology and the leader of a consortium called Quantum Communication Channels for Fundamental Physics, which conducted the research. “And we hope that we can make adult wormholes and toddler wormholes step-by-step.”
In their report, published Wednesday in Nature, the researchers described the result in measured words: “This work is a successful attempt at observing traversable wormhole dynamics in an experimental setting.”
The wormhole that Dr. Spiropulu and her colleagues created and exploited is not a tunnel through real physical space but rather through an “emergent” two-dimensional space. The “black holes” were not real ones that could swallow the computer but lines of code in a quantum computer. Strictly speaking, the results apply only to a simplified “toy model” of a universe — in particular, one that is akin to a hologram, with quantum fields on the edge of space-time determining what happens within, sort of in the way that the label on a soup can describes the contents.
To be clear: The results of this experiment do not offer the prospect anytime soon, if ever, of a cosmic subway through which to roam the galaxy like Jodie Foster in the movie “Contact” or Matthew McConaughey in “Interstellar.”
“I guess the key question, which is perhaps hard to answer, is: Do we say from the simulation it’s a real black hole?” Daniel Jafferis, a physics professor at Harvard, said. “I kind of like the term ‘emergent black hole.’”
He added: “We are just using the quantum computer to find out what it would look and feel like if you were in this gravitational situation.” He and Alexander Zlokapa, a doctoral student at the Massachusetts Institute of Technology, are the lead authors of the paper.
Physicists reacted to the paper with interest and caution, expressing concern that the public and media would mistakenly think that actual physical wormholes had been created.
“The most important thing I’d want New York Times readers to understand is this,” Scott Aaronson, a quantum computing expert at the University of Texas in Austin, wrote in an email. “If this experiment has brought a wormhole into actual physical existence, then a strong case could be made that you, too, bring a wormhole into actual physical existence every time you sketch one with pen and paper.”
Daniel Harlow, a physicist at M.I.T. who was not involved in the experiment, noted that the experiment was based on a model of quantum gravity that was so simple, and unrealistic, that it could just as well have been studied using a pencil and paper.
“So I’d say that this doesn’t teach us anything about quantum gravity that we didn’t already know,” Dr. Harlow wrote in an email. “On the other hand, I think it is exciting as a technical achievement, because if we can’t even do this (and until now we couldn’t), then simulating more interesting quantum gravity theories would CERTAINLY be off the table.” Developing computers big enough to do so might take 10 or 15 years, he added.
Leonard Susskind, a physicist at Stanford University who was not part of the team, agreed. “They’re learning that they could do this experiment,” he said, adding: “The really interesting thing here is the possibility of analyzing purely quantum phenomena using general relativity, and who knows where that’s going to go.”
The two faces of Einstein
Wormholes entered the physics lexicon in 1935 as one of the weirder predictions of Albert Einstein’s general theory of relativity, which describes how matter and energy warp space to create what we call gravity. That year Einstein and his colleague, Nathan Rosen, showed in a paper that shortcuts through space-time, connecting pairs of black holes, could exist. The physicist John Wheeler later called these connectors “wormholes.”
Originally it seemed that wormholes were effectively useless; theory held that they would slam shut the instant anything entered them. They have never been observed outside of science fiction.
A month earlier that same year, in 1935, Einstein, Rosen and Boris Podolsky made another breakthrough, one they thought would discredit the chancy nature of quantum mechanics. They pointed out that quantum rules permitted what Einstein called “spooky action at a distance.” Measuring one of a pair of particles would determine the results of measuring the other particle, even if the two were light-years apart. Einstein thought this prediction was absurd, but physicists now call it “entanglement” and use it every day in the lab.
Until a few years ago, such quantum tricks weren’t thought to have anything to do with gravity. As a result, physicists were left with no theory of “quantum gravity” to explain what happened when the realms of inner space and outer space collided, as in the Big Bang or inside black holes.
But in 2013 Juan Maldacena, a theoretical physicist at the Institute for Advanced Study in Princeton, and Dr. Susskind proposed that these two phenomena — spooky action and wormholes — were actually two sides of the same coin, each described in a different but complementary mathematical language.
Those spooky, entangled particles, by this logic, were connected by equally mysterious wormholes. Quantum mechanics could be enlisted to study gravity, and vice versa. The equations that describe quantum phenomena turned out to have analogues in the Einsteinian equations for gravity.
“It’s mostly a matter of taste which description you use because they give exactly the same answer,” Dr. Jafferis said. “And that was an incredible discovery.”
The recent wormhole experiment sought to employ the mathematics of general relativity to examine an aspect of quantum magic, known as quantum teleportation, to see if some new aspect of physics or gravity might be revealed.
In quantum teleportation, physicists use a set of quantum manipulations to send information between two particles — inches or miles apart — that are entangled in a pair, without the physicists knowing what the message is. The technology is expected to be the heart of a next-generation, unhackable “quantum internet.”
Physicists like to compare the teleportation process to two cups of tea. Drop a cube of sugar into one teacup, and it promptly dissolves — then, after a tick of the quantum clock, the cube reappears intact in the other teacup.
The experiment became conceivable after a pair of papers by Dr. Susskind and, independently, by Dr. Jafferis, Ping Gao of M.I.T., and Aron Wall, a theoretical physicist at the University of Cambridge. They suggested a way that wormholes could be made traversable, after all. What was needed, Dr. Gao and his collaborators said, was a small dose of negative energy at the exit end of the wormhole to prop open the hatch long enough for information to escape.
In classical physics, there is no such thing as negative energy. But in quantum theory, energy can be negative, generating an antigravitational effect. For example, so-called virtual particles, which flit in and out of existence using energy borrowed from empty space, can fall into a black hole, carrying a debt to nature in the form of energy that the black hole must then pay back. This slow leak, Stephen Hawking calculated in 1974, causes the black hole to lose energy and shrink.
When Dr. Spiropulu proposed trying to recreate this wormhole magic on a quantum computer, her colleagues and sponsors at the Department of Energy “thought I was completely nuts,” she recalled. “But Jafferis said, Let’s do it.”
In ordinary computers, including the phone in your pocket, the currency of calculation is bits, which can be ones or zeros. Quantum computers run on qubits, which can be 0 or 1 or anywhere in between until they are measured or observed. This makes quantum computers super powerful for certain kinds of tasks, like factoring large numbers and (maybe one day) cracking cryptographic codes. In essence, a quantum computer runs all the possible variations of the program simultaneously to arrive at a solution.
“We make uncertainty an ally and embrace it,” Dr. Spiropulu said.
To reach their full potential, quantum computers will need thousands of working qubits and a million more “error correction” qubits. Google hopes to reach such a goal by the end of the decade, according to Hartmut Neven, head of the company’s Quantum Artificial Intelligence lab in Venice, Calif., who is also on Dr. Spiropulu’s team.
The Caltech physicist and Nobel laureate Richard Feynman once predicted that the ultimate use of this quantum power might be to investigate quantum physics itself, as in the wormhole experiment.
“I’m excited to see that researchers can live out Feynman’s dream,” Dr. Neven said.
The wormhole experiment was carried out on a version of Google’s Sycamore 2 computer, which has 72 qubits. Of these, the team used only nine to limit the amount of interference and noise in the system. Two were reference qubits, which played the roles of input and output in the experiment.
The seven other qubits held the two copies of code describing a “sparsified” version of an already simple model of a holographic universe called SYK, named after its three creators: Subir Sachdev of Harvard, Jinwu Ye of Mississippi State University and Alexei Kitaev of Caltech. Both SYK models were packed into the same seven qubits. In the experiment these SYK systems played the role of two black holes, one by scrambling the message into nonsense — the quantum equivalent of swallowing it — and then the other by popping it back out.
“Into this we throw a qubit,” Dr. Lykken said, referring to the input message — the quantum analog of a series of ones and zeros. This qubit interacted with the first copy of the SYK qubit; its meaning was scrambled into random noise and it disappeared.
Then, in a tick of the quantum clock, the two SYK systems were connected and a shock of negative energy went from the first system to the second one, briefly propping open the latter.
The signal then reappeared in its original unscrambled form — in the ninth and last qubit, attached to the second SYK system, which represented the other end of the wormhole.
One clue that the researchers were actually recording “wormholelike” behavior, Dr. Lykken said, was that signals emerged from the other end of the wormhole in the order that they went in.
In a Nature article accompanying Dr. Jafferis’s paper, Dr. Susskind and Adam Brown, a physicist at Stanford, noted that the results might shed light on some still-mysterious aspects of ordinary quantum mechanics. For instance, after the sugar cube dissolves in the first teacup, why does it reappear in the other cup in its original form?
“The surprise is not that the message made it across in some form, but that it made it across unscrambled,” the two authors wrote.
The easiest explanation, they added, is that the message went through a wormhole, albeit a “really short” one, Dr. Lykken said in an interview. In quantum mechanics, the shortest conceivable length in nature is 10⁻³³ centimeters, the so-called Planck length. Dr. Lykken calculated that their wormhole was maybe only three Planck lengths long.
“It’s the smallest, crummiest wormhole you can imagine making,” he said. “But that’s really cool because now we’re clearly doing quantum gravity.”
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