Enlarge / Scientists have found a large black hole that “hiccups,” giving off plumes of gas. (credit: Jose-Luis Olivares, MIT)

In December 2020, astronomers spotted an unusual burst of light in a galaxy roughly 848 million light-years away—a region with a supermassive black hole at the center that had been largely quiet until then. The energy of the burst mysteriously dipped about every 8.5 days before the black hole settled back down, akin to having a case of celestial hiccups.

Now scientists think they've figured out the reason for this unusual behavior. The supermassive black hole is orbited by a smaller black hole that periodically punches through the larger object's accretion disk during its travels, releasing a plume of gas. This suggests that black hole accretion disks might not be as uniform as astronomers thought, according to a new paper published in the journal Science Advances.

Co-author Dheeraj "DJ" Pasham of MIT's Kavli Institute for Astrophysics and Space research noticed the community alert that went out after the All Sky Automated Survey for SuperNovae (ASAS-SN) detected the flare, dubbed ASASSN-20qc. He was intrigued and still had some allotted time on the X-ray telescope, called NICER (the Neutron star Interior Composition Explorer) on board the International Space Station. He directed the telescope to the galaxy of interest and gathered about four months of data, after which the flare faded.

Enlarge (credit: vital )

There's a strong consensus that tackling most useful problems with a quantum computer will require that the computer be capable of error correction. There is absolutely no consensus, however, about what technology will allow us to get there. A large number of companies, including major players like Microsoft, Intel, Amazon, and IBM, have all committed to different technologies to get there, while a collection of startups are exploring an even wider range of potential solutions.

We probably won't have a clearer picture of what's likely to work for a few years. But there's going to be lots of interesting research and development work between now and then, some of which may ultimately represent key milestones in the development of quantum computing. To give you a sense of that work, we're going to look at three papers that were published within the last couple of weeks, each of which tackles a different aspect of quantum computing technology.

Hot stuff

Error correction will require connecting multiple hardware qubits to act as a single unit termed a logical qubit. This spreads a single bit of quantum information across multiple hardware qubits, making it more robust. Additional qubits are used to monitor the behavior of the ones holding the data and perform corrections as needed. Some error correction schemes require over a hundred hardware qubits for each logical qubit, meaning we'd need tens of thousands of hardware qubits before we could do anything practical.

Enlarge / A new image from the Event Horizon Telescope has revealed powerful magnetic fields spiraling from the edge of a supermassive black hole at the center of the Milky Way, Sagittarius A*. (credit: EHT Collaboration)

Physicists have been confident since the1980s that there is a supermassive black hole at the center of the Milky Way galaxy, similar to those thought to be at the center of most spiral and elliptical galaxies. It's since been dubbed Sagittarius A* (pronounced A-star), or SgrA* for short. The Event Horizon Telescope (EHT) captured the first image of SgrA* two years ago. Now the collaboration has revealed a new polarized image (above) showcasing the black hole's swirling magnetic fields. The technical details appear in two new papers published in The Astrophysical Journal Letters. The new image is strikingly similar to another EHT image of a larger supermassive black hole, M87*, so this might be something that all such black holes share.

The only way to "see" a black hole is to image the shadow created by light as it bends in response to the object's powerful gravitational field. As Ars Science Editor John Timmer reported in 2019, the EHT isn't a telescope in the traditional sense. Instead, it's a collection of telescopes scattered around the globe. The EHT is created by interferometry, which uses light in the microwave regime of the electromagnetic spectrum captured at different locations. These recorded images are combined and processed to build an image with a resolution similar to that of a telescope the size of the most distant locations. Interferometry has been used at facilities like ALMA (the Atacama Large Millimeter/submillimeter Array) in northern Chile, where telescopes can be spread across 16 km of desert.

In theory, there's no upper limit on the size of the array, but to determine which photons originated simultaneously at the source, you need very precise location and timing information on each of the sites. And you still have to gather sufficient photons to see anything at all. So atomic clocks were installed at many of the locations, and exact GPS measurements were built up over time. For the EHT, the large collecting area of ALMA—combined with choosing a wavelength in which supermassive black holes are very bright—ensured sufficient photons.

Enlarge / Density waves in a Bose-Einstein condensate. (credit: NASA )

In the basement of Kirchhoff-Institut für Physik in Germany, researchers have been simulating the Universe as it might have existed shortly after the Big Bang. They have created a tabletop quantum field simulation that involves using magnets and lasers to control a sample of potassium-39 atoms that is held close to absolute zero. They then use equations to translate the results at this small scale to explore possible features of the early Universe.

The work done so far shows that it’s possible to simulate a Universe with a different curvature. In a positively curved universe, if you travel in any direction in a straight line, you will come back to where you started. In a negatively curved universe, space is bent in a saddle shape. The Universe is currently flat or nearly flat, according to Marius Sparn, a PhD student at Kirchhoff-Institut für Physik. But at the beginning of its existence, it might have been more positively or negatively curved.

Around the curve

“If you have a sphere that's really huge, like the Earth or something, if you see only a small part of it, you don't know—is it closed or is it infinitely open?” said Sabine Hossenfelder, member of the Munich Center for Mathematical Philosophy. “It becomes a philosophical question, really. The only things we know come from the part of the Universe we observe. Normally, the way that people phrase it is that, for all we know, the curvature in this part of the Universe is compatible with zero.”

Enlarge / The selected films span several decades to show how Hollywood's treatment of time travel in Hollywood has evolved. (credit: Aurich Lawson | Getty Images)

Since antiquity, humans have envisioned various means of time travel into the future or the past. The concept has since become a staple of modern science fiction. In particular, the number of films that make use of time travel has increased significantly over the decades, while the real-world science has evolved right alongside them, moving from simple Newtonian mechanics and general relativity to quantum mechanics and the notion of a multiverse or more exotic alternatives like string theory.

But not all time-travel movies are created equal. Some make for fantastic entertainment but the time travel makes no scientific or logical sense, while others might err in the opposite direction, sacrificing good storytelling in the interests of technical accuracy. What we really need is a handy guide to help us navigate this increasingly crowded field to ensure we get the best of both worlds, so to speak. The Ars Guide to Time Travel in the Movies is here to help us all make better, more informed decisions when it comes to choosing our time travel movie fare.

This is not meant to be an exhaustive list; rather, we selected films that represented many diverse approaches to time travel across multiple subgenres and decades. We then evaluated each one—grading on a curve—with regard to its overall entertainment value and scientific logic, with the final combined score determining a film's spot on the overall ranking. For the “science” part of our scoring system, we specifically took three factors into account. First and foremost, does the time travel make logical sense? Second, is the physical mechanism of time travel somewhat realistic? And third, does the film use time travel in narratively interesting ways? So a movie like Looper , which makes absolutely no sense if you think about it too hard, gets points for weaving time paradoxes thoroughly into the fabric of the story.

Astronomers involved with the Telescope Array experiment in Utah's West Desert have detected an ultra-high-energy cosmic ray (UHECR) with a whpping energy level of 244 EeV, according to a new paper published in the journal Science. It's the most energetic cosmic ray detected since 1991, when astronomers detected the so-called "Oh-My-God' particle , with energies of an even more impressive 320 EeV. Astronomers have dubbed this latest event the "Amaterasu" particle, after the Shinto sun goddess said to have created Japan. One might even call it the "Oh-My-Goddess" particle.

Cosmic rays are highly energetic subatomic particles traveling through space near the speed of light. Technically, a cosmic ray is just an atomic nucleus made up of a proton or a cluster of protons and neutrons. Most originate from the Sun, but others come from objects outside our solar system. When these rays strike the Earth’s atmosphere, they break apart into showers of other particles (both positively and negatively charged).

They were first discovered in 1912 by Austrian physicist Victor Hess via a series of ascents in a hydrogen balloon to take measurements of radiation in the atmosphere with an electroscope. He found that the rate of ionization was a good three times the rate at sea level, thereby disproving a competing theory that this radiation came from the rocks of  Earth. If you've ever seen a cloud chamber in a science museum, cosmic ray tracks look like wispy little white lines, similar to tiny jet contrails.

Science 101 tells us that the twinkling appearance of stars from our vantage point on Earth is due to atmospheric effects: winds and varying temperatures and densities in the air bend and distort the light. But stars have another sort of "twinkle" produced by how gases ripple in waves across their surface, an effect that could provide astronomers with a handy means of exploring the interior of massive stars to learn more about how they form and evolve. But the effect is much too small to be readily detected by telescopes.

So scientists have now developed the first 3D simulations of that innate twinkle, according to a recent paper published in the journal Nature Astronomy. As a bonus, the researchers converted the data from those rippling waves of gas into an audible sound, so now we can all take a moment to listen to "Twinkle, Twinkle, Little Star" (see video above) and Gustav Holst's "Jupiter" (see video below) in the "language" of the stars.

“Motions in the cores of stars launch waves like those on the ocean,” said co-author Evan Anders of Northwestern University. “When the waves arrive at the star’s surface, they make it twinkle in a way that astronomers may be able to observe. For the first time, we have developed computer models which allow us to determine how much a star should twinkle as a result of these waves. This work allows future space telescopes to probe the central regions where stars forge the elements we depend upon to live and breathe.”

Enlarge / French physicist Gerard Liger-Belair studied CO₂ levels in 13 old champagne vintages in three different bottle sizes. (credit: Andy Roberts/Getty Images)

A large part of the pleasure of imbibing a glass of champagne comes from its effervescence: all those bubbles rising from the glass and ticking the nose and palate. If there's no fizz, there's no fun—and also less flavor and aromas to savor. A recent paper published in the journal ACS Omega found that the size of the champagne bottle is a key factor in determining when the wine inside will go flat.

As we've reported previously , champagne's effervescence arises from the nucleation of bubbles on the glass walls. Once they detach from their nucleation sites, the bubbles grow as they rise to the liquid surface, where they burst. This typically occurs within a couple of milliseconds, and the distinctive crackling sound is emitted when the bubbles rupture. The bubbles even "ring" at specific resonant frequencies , depending on their size, so it's possible to "hear" the size distribution of bubbles as they rise to the surface in a glass of champagne.

Prior studies have shown that when the bubbles in champagne burst, they produce droplets that release aromatic compounds believed to enhance the flavor. Larger bubbles enhance the release of aerosols into the air above the glass—bubbles on the order of 1.7 mm across at the surface. French physicist Gerard Liger-Belair of the University of Reims Champagne-Ardenne is one of the foremost scientists studying many different aspects of champagne and has now turned his attention to exploring how long champagne can age in the bottle before the carbonation dissipates to the point where those all-important bubbles can no longer form.

Enlarge / Bare, reddish-hued circular patches in the Namib Desert known as "fairy circles" are also found in northwestern Australia. (credit: UHH/MIN/Juergens)

Himba bushmen in the Namibian grasslands have long passed down legends about the region's mysterious fairy circles: bare, reddish-hued circular patches that are also found in northwestern Australia. In the last 10 years, scientists have heatedly debated whether these unusual patterns are due to sand termites or to an ecological version of a self-organizing Turing mechanism. Last year, a team of scientists reported what they deemed definitive evidence of the latter, thus ruling out sand termites, but their declaration of victory may have been premature. A recent paper published in the journal Perspectives in Plant Ecology, Evolution, and Systematics offers a careful rebuttal of those 2022 findings, concluding that sand termites may be to blame after all.

As we've reported previously, the fairy circles can be as large as several feet in diameter. Dubbed "footprints of the gods," it's often said they are the work of the Himba deity Mukuru , or an underground dragon whose poisonous breath kills anything growing inside those circles. Scientists have their own ideas.

One theory—espoused by study co-author Norbert Jürgens, a biologist at the University of Hamburg in Germany—attributed the phenomenon to a particular species of termite ( Psammmotermes allocerus ), whose burrowing damages plant roots, resulting in extra rainwater seeping into the sandy soil before the plants can suck it up—giving the termites a handy water trap as a resource. As a result, the plants die back in a circle from the site of an insect nest. The circles expand in diameter during droughts because the termites must venture farther out for food.