We’ve studied enough comets from our solar system to know that they formed during its early stages, when there was a ton of material swirling around and coalescing into individual bodies. They are made primarily from ice, but in order to survive, they have to form at a distance where the sun’s heat and radiation won’t instantly melt them. Other star systems presumably give rise to comets in the same way. The more distant they are from the star’s radiation, the more they retain their original composition and chemistry from their formation 4.5 billion years ago or so. This “pristine” quality means comets are like preserved time capsules of star systems in their infancies.
Comet dust in particular tells us what the solar system was made of when it first gave birth to comets, and the same principle can theoretically apply to interstellar comets. “Studying the composition and structure of dust particles in the dust coma of 2I/Borisov, we can make educated guesses about the formation conditions and locations of the dust,” says Bin Yang, an astronomer with the European Southern Observatory and the lead author of one of the studies.
The first paper, led by Stefano Bagnulo at Armagh Observatory and Planetarium in the UK, focuses on reflected light. Light is composed of waves, and these waves normally oscillate in many different directions at once. When these waves are polarized, however, they oscillate in one specific direction. If light is polarized by a comet’s coma (the hazy outer shell of gas and dust expelled as the comet is heated by the sun), studying this light can give information on the size and composition of the dust, which helps us understand how the comet formed—and, by extension, provides a glimpse into the history of its original star system.
The new data, collected by the Very Large Telescope based in Chile, tells us that the light reflected from Borisov and filtered through its coma is more polarized than the light from any other object that we’ve studied in the solar system. This is a sign the coma’s particles are small and very fine, which suggests they have not been much disturbed by any star’s radiation and heat (forces that would otherwise cause larger chunks to be haphazardly ejected from the surface). The authors conclude that Borisov is perhaps one of the most pristine objects ever detected. The only object whose polarization comes close is C/Hale-Bopp, perhaps the brightest comet ever observed, and certainly one of the most widely studied comets of the 20th century. Hale-Bopp is thought to have come close to the sun only once before its most recent solar flyby in 1997. So the authors think similar conditions may have given rise to both Borisov and Hale-Bopp, in two different star systems.
Meanwhile, the team led by Yang had set out to understand how Borisov formed, using the VLT as well as Chile’s Atacama Large Millimeter/submillimeter Array (ALMA) to detect heat from large particles hanging in Borisov’s coma.
According to these observations, Borisov’s coma consists of compact, millimeter-size grains—pebbles that are unusually large for a comet. These pebbles, rich in carbon monoxide and water, probably formed first in the inner region of the star system, before being transported outward and gradually mixing with various ices formed at different locations farther from the star. This “gravitational stirring,” induced by giant planets, is thought to have happened in our own solar system (it’s even thought to have helped Hale-Bopp form). Borisov basically came together as an agglomeration of material from different parts of its star system, before finding a secluded place to call home far from its parent star.
Taken together, the findings help tell us a few things. An abundance of carbon monoxide and water in the dust suggests the comet has resided in low-temperature environments (i.e., far away from a star), where those compounds could have remained cold and stable, for nearly all its life. The finding of “pristine” characteristics bolsters this idea.
The similarities between Borisov and Hale-Bopp, along with evidence that both comets’ star systems experienced gravitational stirring, suggests that the evolution of our solar system is perhaps not as unique as we might have thought. That would also suggest the conditions that give rise to a habitable planet like Earth are more common in the galaxy than imagined.
Or perhaps this is a red herring, and Borisov’s home star system is actually very exotic. Neil Dello Russo, an astronomer at Johns Hopkins University who was not involved with the study, says he was surprised at how high the carbon monoxide and water values were—higher than anything observed in comets from our solar system.
Other questions linger as well. The new findings still cannot tell us exactly when the pebbles in the coma formed, or even what they’re made from.
The biggest problem might be that the two papers seem to promote two different ideas about the particles that make up Borisov: Yang’s paper prominently unpacks the discovery of large pebbles in the coma, while Bagnulo’s paper suggests the coma is dominated by smoke-like small grains that can cause extreme polarization of light. But Michael Kelley, a comet scientist at the University of Maryland who was not involved with the new studies, believes this is likely “just a consequence of the different techniques”—each favoring the detection of one specific type of particle. Future analyses should be able to compare and combine both sets of data and reconcile them as parts of Borisov’s evolution.
Borisov is a weird object, but what is truly weird is the notion that it might hail from a star system not too different from our own. This interstellar comet might be one of the most normal visitors we’ve ever said hello to.
Yann LeCun has a bold new vision for the future of AI
Melanie Mitchell, an AI researcher at the Santa Fe Institute, is also excited to see a whole new approach. “We really haven’t seen this coming out of the deep-learning community so much,” she says. She also agrees with LeCun that large language models cannot be the whole story. “They lack memory and internal models of the world that are actually really important,” she says.
Natasha Jaques, a researcher at Google Brain, thinks that language models should still play a role, however. It’s odd for language to be entirely missing from LeCun’s proposals, she says: “We know that large language models are super effective and bake in a bunch of human knowledge.”
Jaques, who works on ways to get AIs to share information and abilities with each other, points out that humans don’t have to have direct experience of something to learn about it. We can change our behavior simply by being told something, such as not to touch a hot pan. “How do I update this world model that Yann is proposing if I don’t have language?” she asks.
There’s another issue, too. If they were to work, LeCun’s ideas would create a powerful technology that could be as transformative as the internet. And yet his proposal doesn’t discuss how his model’s behavior and motivations would be controlled, or who would control them. This is a weird omission, says Abhishek Gupta, the founder of the Montreal AI Ethics Institute and a responsible-AI expert at Boston Consulting Group.
“We should think more about what it takes for AI to function well in a society, and that requires thinking about ethical behavior, amongst other things,” says Gupta.
Yet Jaques notes that LeCun’s proposals are still very much ideas rather than practical applications. Mitchell says the same: “There’s certainly little risk of this becoming a human-level intelligence anytime soon.”
LeCun would agree. His aim is to sow the seeds of a new approach in the hope that others build on it. “This is something that is going to take a lot of effort from a lot of people,” he says. “I’m putting this out there because I think ultimately this is the way to go.” If nothing else, he wants to convince people that large language models and reinforcement learning are not the only ways forward.
“I hate to see people wasting their time,” he says.
The Download: Yann LeCun’s AI vision, and smart cities’ unfulfilled promises
“We’re addicted to being on Facebook.”
—Jordi Berbera, who runs a pizza stand in Mexico City, tells Rest of World why he has turned to selling his wares through the social network instead of through more conventional food delivery apps.
The big story
“Am I going crazy or am I being stalked?” Inside the disturbing online world of gangstalking
Jenny’s story is not linear, the way that we like stories to be. She was born in Baltimore in 1975 and had a happy, healthy childhood—her younger brother Danny fondly recalls the treasure hunts she would orchestrate. In her late teens, she developed anorexia and depression and was hospitalized for a month. Despite her struggles, she graduated high school and was accepted into a prestigious liberal arts college.
There, things went downhill again. Among other issues, chronic fatigue led her to drop out. When she was 25 she flipped that car on Florida’s Sunshine Skyway Bridge in an apparent suicide attempt. At 30, after experiencing delusions that she was pregnant, she was diagnosed with schizophrenia. She was hospitalized for half a year and began treatment, regularly receiving shots of an antipsychotic drug. “It was like having my older sister back again,” Danny says.
On July 17, 2017, Jenny jumped from the tenth floor of a parking garage at Tampa International Airport. After her death, her family searched her hotel room and her apartment, but the 42-year-old didn’t leave a note. “We wanted to find a reason for why she did this,” Danny says. And so, a week after his sister’s death, Danny—a certified ethical hacker—decided to look for answers on Jenny’s computer. He found she had subscribed to hundreds of gangstalking groups across Facebook, Twitter, and Reddit; online communities where self-described “targeted individuals” say they are being monitored, harassed, and stalked 24/7 by governments and other organizations—and the internet legitimizes them. Read the full story.
The US Supreme Court has overturned Roe v. Wade. What does that mean?
Access to legal abortion is now subject to state laws, allowing each state to decide whether to ban, restrict or allow abortion. Some parts of the country are much stricter than others—Arkansas, Oklahoma and Kentucky are among the 13 states with trigger laws that immediately made abortion illegal in the aftermath of the ruling. In total, around half of states are likely to either ban or limit access to the procedure, with many of them refusing to make exceptions, even in pregnancies involving rape, incest and fetuses with genetic abnormalities. Many specialized abortion clinics may be forced to close their doors in the next few days and weeks.
While overturning Roe v Wade will not spell an end to abortion in the US, it’s likely to lower its rates, and force those seeking them to obtain them using different methods. People living in states that ban or heavily restrict abortions may consider travelling to other areas that will continue to allow them, although crossing state lines can be time-consuming and prohibitively expensive for many people facing financial hardship.
The likelihood that anti-abortion activists will use surveillance and data collection to track and identify people seeking abortions is also higher following the decision. This information could be used to criminalize them, making it particularly dangerous for those leaving home to cross state lines.
Vigilante volunteers already stake out abortion clinics in states including Mississippi, Florida and North Carolina, filming people’s arrival on cameras and recording details about them and their cars. While they deny the data is used to harass or contact people seeking abortions, experts are concerned that footage filmed of clients arriving and leaving clinics could be exploited to target and harm them, particularly if law enforcement agencies or private groups were to use facial recognition to identify them.
Another option is to order so-called abortion pills to discreetly end a pregnancy at home. The pills, which are safe and widely prescribed by doctors, are significantly less expensive than surgical procedures, and already account for the majority of abortions in the US.