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Saturn’s insides are sloshing around

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Saturn’s insides are sloshing around


This diffuse core extends out to about 60% of Saturn’s radius—a huge leap from the 10 to 20% of a planet’s radius that a traditional core would occupy. 

One of the wildest aspects of the study is that the findings did not come from measuring the core directly—something we’ve never been able to do. Instead, Mankovich and Fuller turned to seismographic data on Saturn’s rings first collected by NASA’s Cassini mission, which explored the Saturnian system from 2004 to 2017.

“Saturn essentially rings like a bell at all times,” says Mankovich. As the core wobbles, it creates gravitational perturbations that affect the surrounding rings, creating subtle “waves” that can be measured. When the planet’s core was oscillating, Cassini was able to study Saturn’s C ring (the second block of rings from the planet) and measure the small yet consistent gravitational “ringing” caused by the core. 

Mankovich and Fuller looked at the data and created a model for Saturn’s structure that would explain these seismographic waves—and the result is a fuzzy interior. “This study is the only direct evidence for a diffuse core structure in a fluid planet to date,” says Mankovich.

Mankovich and Fuller think the reason the structure works is that the rocks and ice near Saturn’s center are soluble in hydrogen, allowing the core to behave like a fluid rather than a solid. Their model suggests that Saturn’s diffuse core contains rocks and ice adding up to more than 17 times the mass of the entire Earth—so that’s a lot of material wobbling around. 

A diffuse core could have a few big implications for how Saturn works. The most significant is that it would stabilize part of the interior against convective heat, which otherwise would roil Saturn’s insides with turbulence. In fact, this stabilizing influence gives rise to the internal gravity waves that influence Saturn’s rings. Moreover, the diffuse core would explain why Saturn’s surface temperatures are higher than what traditional convective models would suggest. 

Still, Mankovich acknowledges that the model is limited in some important ways. It can’t explain what scientists have observed about Saturn’s magnetic field, which is bizarre in a lot of ways (for example, it exhibits a nearly perfect symmetry on its axis, which is quite unusual). He and Fuller hope that future investigations can constrain the interior more narrowly and clue scientists in to how the planet’s core might affect its magnetic field.

They also hope that NASA’s Juno mission might reveal a similar diffuse core within Jupiter. That would go a long way to affirming suspicions that when giant planets form, the process naturally creates gradients of material as opposed to clean and solid cores. Some research using gravity data collected by Juno seems to support this idea as well

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Yann LeCun has a bold new vision for the future of AI

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The Download: Yann LeCun’s AI vision, and smart cities’ unfulfilled promises


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.

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The Download: Yann LeCun’s AI vision, and smart cities’ unfulfilled promises

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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

August 2020

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.

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The US Supreme Court has overturned Roe v. Wade. What does that mean?

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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.

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