Scientists used quantumly entangled two optical atomic clocks at a distance of two meters, reports a new study. The achievement opens the door to probing fundamental reality on a deep level.

It’s hard to be precise, especially when it comes to time. Not even your iPhone is a perfect timekeeper, and in fact, the best device is something that’s not easily available. Atomic clocks use an atom’s vibrational patterns to measure time and frequency. The upgraded version, the optical atomic clock, can do an even better job by pairing elements like strontium or ytterbium with lasers. 

And while the main application of optical atomic clocks has been timekeeping and navigation, their precision can also be used in searching for dark matter, looking at the space-time variation of fundamental constants, and understanding Earth’s figure, orientation in space, and gravity. The idea of using these clocks to expand our understanding of these natural phenomena is the focus of the study, published on Wednesday in Nature by researchers at Oxford University. 

“When two atoms are entangled, then you cannot describe the state of one without describing the state of the other,” Bethan Nichols, one of the study’s authors, wrote in an email to Motherboard. "This is what Einstein is describing with the phrase ‘spooky action at a distance,’ i.e., if something happens to one atom, it can immediately affect the other with no apparent communication between them.” 

Entanglement with atomic clocks allows researchers to go beyond traditional boundaries of measurement. 

“In order to measure very small changes in the relative atomic frequencies between two atoms in separate locations, we need very high measurement precision,” Nichols wrote. “There is a limit on the measurement precision of independent systems. Entanglement can be used to go past that limit to the ultimate limit allowed by quantum theory.”

Nichols emphasized that there are many groups that have made accurate measurements of optical atomic clock frequencies and that have been working in this field for a long time. But while previous studies have demonstrated that clock entanglement could potentially improve measuring quality, this experiment differs in that the clocks are not actually in the same quantum system. 

“There have been demonstrations of entanglement enhanced measurements on optical atomic clocks for atoms that are close to one another in the same system,” Nichols wrote. “However, this is the first demonstration for atoms that are further apart in separate systems.” 

Scientists have invented a device that uses intense sound waves to levitate tiny objects and move them without any direct contact, a technique that has been captured in surreal footage of small sticks, beads, and droplets suspended eerily in the air, as if enchanted.

The device, called LeviPrint, pioneers a new technique for contactless manufacturing, and debuts an unprecedented manipulation of elongated objects, according to research published on Wednesday that will be presented at the SIGGRAPH conference in Vancouver, British Columbia, this August.

LeviPrint’s ability to move such small objects, and even liquid droplets, can enable microfabrication of small machines, like watches or camera parts, without risking cross-contamination as a result of direct content. It may also prove useful for bio-engineering because the device “could assemble microscopic objects in cell-culture media and perhaps even inside living beings,” according to the new study.

“Contactless fabrication allows for less cross-contamination, manipulating a wide variety of parts (beads, liquids, sticks, powders…) and moving those parts through holes and cavities,” said Asier Marzo, a researcher at the Public University of Navarre who co-authored the study, in an email. “For example, we built a tiny boat inside a bottle made of metallic mesh by inserting all the components through a small aperture at the side.”

While many teams have experimented with acoustic levitation, a technique that uses the pressure of sound waves to suspend matter, Marzo and his colleagues are the first to combine the manipulation of small particles and droplets into a full prototype for contactless fabrication. LeviPrint is also the first device that uses acoustic traps to suspend elongated objects, which could be useful for manufacturing processes that require beams, sticks or girders. While these tests were performed with air as a medium, there are even more exotic possibilities in water. 

“Most of the coolest applications are when operating in water-based media instead of air,” Marzo said. “The same techniques that worked in air, could translate directly to water-based media. In fact, it is easier since objects weigh less and the ultrasound travels better through water.” 

“The LeviPrint technique could control the orientation of elongated objects inside the body like needles, or tiny probes,” he added, though he noted that the team still needs to develop device emitters that are adapted to perform in water.

While there is solid science underpinning LeviPrint, the bizarre footage of its abilities makes it look like the team is casting a spell. It’s an impression that is not lost on Marzo and his colleagues, even though they have invested years in the nuts-and-bolts of the device.

“The first time you levitate something it’s quite a magical experience, especially when your childhood is full of wizards or sci-fi movies,” Marzo said. “You start slowly moving the element around and observing it from all angles, like focusing all your attention on a magic trick. But you get used to it quickly, and you want to levitate more and more complex stuff and perform faster and more complex movements, searching for the limits of the system.” 

“The limitations that we found on previous devices are a big motivation to create something that could go further,” he added. “We admit that after the last years, we have become quite used to manipulating levitated samples, doing it manually can be a bit tricky since your hand shakes and that vibration can become resonant with the trapped particle. It is like that game of running with an egg on a spoon. So, when we switched to the robotic arm, it was a big relief given its accuracy, speed and the lack of any shakiness.”

In addition to presenting their research later this summer, Marzo and his colleagues hope that other scientists will adopt and adapt LeviPrint for a range of functions.

“The device that we used was a prototype assembled by a couple of researchers that are not experts in electronics, but it was enough to showcase the techniques and hint for potential applications,” Marzo concluded. “Now, a big engineering company can manufacture more powerful and accurate levitators that would provide more precision and the capability to work with materials such as aluminum or even steel. We hope to see a research group with experience in biomedical applications that adopt this technique to operate in water-based media and biomaterials.”

Lightning strikes can be an exhilarating and terrifying sight to behold from the ground, but what’s wilder is that these intense bolts of plasma sometimes powerfully erupt in the opposite direction, zigzagging up into space in dazzling displays known as gigantic jets. 

Now, scientists led by Levi Boggs, a research scientist at the Georgia Tech Research Institute, have described the strongest gigantic jet ever seen, which sprang up from cloudtop in Oklahoma and darted 50 miles above Earth’s surface, where it delivered the largest charge transfer to space on record. 

Whereas most lightning bolts carry fewer than five coulombs (a measurement of charge), this jet transferred a gobsmacking 300 coulombs to the ionosphere, the low end of space, when it struck on May 14, 2018. That is nearly double the previous largest charge by a gigantic jet and is on par with the largest ever recorded for cloud-to-ground strokes.

The jet was captured on film by a nearby citizen scientist with a low-light camera, along with other instruments on the ground and in space, revealing never-before-seen details about these mysterious upward strikes that have “broad implications to lightning physics beyond that of gigantic jets,” according to a study published last week in Science Advances.  

“I was really intrigued because observations of gigantic jets are really rare—only a few per year if that,” Boggs said in an email. “So I seize any chance to study them, because trying to capture them with dedicated field campaigns is very difficult. This was a random chance that I was told about this video, and luckily the event in the video was also observed by a ground-based radio mapping network and optical instruments in geostationary orbit.”

In addition to its immense charge, the jet has puzzled scientists like Boggs because it emerged from “unusual circumstances” in a “unique thundercloud,” according to the study. Most gigantic jets occur in tropical environments and are located near parts of a storm that are strongly convective, but this one occurred in an area of weak convection. 

“Usually gigantic jets occur from tropical storms near the equator that have really tall cloud tops (18 km) that penetrate into the stratosphere and associated cloud top turbulence, but this event occurred in the middle of the continental U.S. and had relatively low cloud tops (14 km) with little cloud top turbulence,” Boggs said. 

“There was no lightning activity before the gigantic jet in the parent storm cell, which has never been the case from past observations,” he continued. “This allowed the parent storm to accumulate a significant amount of electric charge, which enabled the gigantic jet to transfer the largest amount of charge on record to the ionosphere (300 coulombs).”

The citizen scientist footage was shot from the ground in Hawley, Texas, just across the state border, but the jet was also detected by a sophisticated mapping system for very high frequency (VHF) radio signals sparked by lightning bolts, two Next Generation Weather Radar (NEXRAD) stations, and NOAA's Geostationary Operational Environmental Satellite (GOES) network.

Boggs and his colleagues scoured through this fortuitous glut of data looking for clues about the origin and dynamics of the Oklahoma jet. The results confirmed theories about the behavior of key plasma components of lightning bolts, called streamers and leaders, which are about 400 degrees Fahrenheit and a whopping 8,000 degrees Fahrenheit, respectively.

“The combined 3D radio and optical data provide key insight into the plasma nature of gigantic jets,” the team said. “In addition, the radio and optical data show the first clear evidence that the VHF observed by lightning networks is produced by streamers ahead of the leader.”

Though the Oklahoma jet provided this amazing glimpse into an unrivaled jet, many questions about these elusive events remain. Solving these mysteries is an intriguing scientific endeavor on its own merits, but it also has practical consequences because gigantic jets may scramble spacecraft operations.

“Since these events connect with the lower edge of space, and transfer charge to that region, they could potentially have effects on space weather which could affect communications and electromagnetic signals between ground and satellites in orbit,” Boggs said. He also noted that while it's possible that the jets could strike an aircraft, it is very unlikely because pilots avoid flying over thunderclouds.

Nobody is even sure how many of these jets strike space each year, with estimates ranging from 1,000 to 50,000, leaving plenty of room for future discoveries. To that end,Boggs and his colleagues are hoping to observe more of these brilliant events, which might potentially illuminate the skies with gamma rays, the most energetic form of light. 

“Our results suggest that as the discharge escapes the cloud, the electric field at the tip should be extremely large, potentially large enough to produce gamma rays,” Boggs concluded. “Terrestrial gamma ray flashes (TGFs) have been observed for several years now from lightning, but never from a gigantic jet. Our results indicate that gigantic jets may also produce TGFs.”

Black holes are regions in spacetime with such strong gravitational fields that nothing can escape their boundaries, not even light. As a result, most of these massive objects invisibly drift through space, making it difficult to resolve the many open questions about their mind-bending properties.

Now, scientists have suggested there may be a way to confirm a key mystery about black holes—whether they produce vortex structures—by searching for specific signatures in space. These vortexes would be structurally similar to the swirling maelstroms of tornadoes and whirlpools, but they would arise in multiple places on black holes instead. 

In addition to shedding light on black holes, these clues could potentially open “an observational window to various hidden sectors” of the universe, including the nature of dark matter, according to a recent study published in Physical Review Letters.

While popular depictions of black holes often make them look like giant space vortexes, the presence of vorticity in these entities is a matter of debate. Researchers led by Gia Dvali, director at the Max Planck Institute for Physics in Germany, have presented new theoretical evidence that rapidly spinning black holes “naturally support a vortex structure” and that black hole vortexes (also known as vortices) could have “macroscopically observable consequences,” reports the study.

“The microscopic structure of black holes remains to be understood,” Dvali and his colleagues said in the study. “One of the main obstacles is the lack of experimental probes of black hole quantum properties. In this light, it is very important to identify and explore those microscopic theories that lead to macroscopically observable phenomena.” 

“We shall create awareness about one such phenomenon: vorticity,” the team added. “We believe that…the vorticity property in black holes can be understood without entering into the technicalities of quantum gravitational computations.”

The new research was partially inspired by experimental studies of Bose–Einstein condensates, an ultracold state of matter with bizarre quantum properties that are useful for modeling black hole behaviors.Many laboratory tests have revealed vortex formation in these condensates, and some models suggest that black holes are Bose–Einstein condensates made of “gravitons,” which are the hypothetical “quanta of spacetime itself,” according to study co-author Florian Kühnel.

“Bose-Einstein condensates as a state of matter are well known to exist in many circumstances, with numerous experimental realizations,” said Kühnel, who is a cosmologist at Ludwig Maximilian University of Munich, in an email to Motherboard. “In those, it has been shown that their fast rotation yields the appearance of vortex structures. We realized this similarity and looked [to see] if vortices also appear in the framework of Bose-Einstein condensates of gravitons—and indeed found them!”

The researchers confirmed the possible presence of black hole vorticity in theoretical models based on the experimental data. The results have many implications—for instance, they might explain why rapidly rotating black holes don’t seem to produce Hawking radiation, a type of thermal glow that is thought to be emitted by some of these objects. 

The structures could also lead to extraordinary breakthroughs beyond black holes, including the opportunity to open a “portal into the sector of dark matter,” the study’s authors wrote. Dark matter is a mysterious substance that does not fit into the “standard model” that currently explains our universe.

“Dark matter could be made of particles of extremely small electric charge,” several orders of magnitude smaller than an electron, said Michael Zantedeschi, a PhD researcher at the Max Planck Institute of Physics and a co-author of the study, in an email. “As we show, the interaction of such particles with the black hole vortex would lead to extremely powerful electromagnetic emission from the black hole, which might well be detected.” 

“In turn, the absence of such a signal could constrain the spectrum of those beyond-standard-model particles,” Zantedeschi said. “This is a path we surely plan to explore in depth in the future.”

Extremely luminous objects called active galactic nuclei, which are powered by supermassive black holes that sit at the center of large galaxies, could help reveal black hole vorticity and all of its implications. These nuclei shoot out huge jets of plasma that travel close to light speed and can extend across a million light years. 

Dvali and his colleagues note that these energetic jets might emit magnetic signatures of vorticity in their light, which could be captured and deciphered in telescope images. The jets are also thought to interact with dark matter. As a result, future observations of jets, and the possible signatures of vortexes within them, could inform the major scientific quest to understand dark matter—among many other applications. Indeed, Kühnel noted that there are a host of questions that could be constrained by the team’s work. 

“A very tempting one is to explore under which conditions multiple vortices form since these are known to emerge in laboratory systems,” Kühnel said. “If this indeed turns out to be the case: how are they arranged? Will it be a lattice configuration as observed in laboratories?”

“Then, as regards astrophysical implications, we are currently exploring the generation of magnetic fields from vortical black holes,” he continued. “It seems the vortices can explain the strongest magnetic fields in active galactic nuclei. Furthermore, vortices in so-called primordial black holes (ie. black holes which are produced in the early Universe) could account for the magnetic seeds needed for the observed galactic magnetic fields, thereby solving this conundrum as well as that of the origin of dark matter!”

Update: This article has been updated to include comments from study co-authors Florian Kühnel and Michael Zantedeschi.