Far out cosmology: tiny physics behind big cosmic eruptions (Introduction)

by David Turell , Monday, May 15, 2023, 19:45 (346 days ago) @ David Turell

It is a battle of magnetic forces:

https://www.quantamagazine.org/the-tiny-physics-behind-immense-cosmic-eruptions-20230515/

"During fleeting fits, the sun occasionally hurls a colossal amount of energy into space. Called solar flares, these eruptions last for mere minutes, and they can trigger catastrophic blackouts and dazzling auroras on Earth. But our leading mathematical theories of how these flares work fail to predict the strength and speed of what we observe.

"At the heart of these outbursts is a mechanism that converts magnetic energy into powerful blasts of light and particles. This transformation is catalyzed by a process called magnetic reconnection, in which colliding magnetic fields break and instantly realign, slingshotting material into the cosmos. In addition to powering solar flares, reconnection may power the speedy, high-energy particles ejected by exploding stars, the glow of jets from feasting black holes, and the constant wind blown by the sun.

***

"Nearly all known matter in the universe exists in the form of plasma, a fiery soup of gas where infernal temperatures have stripped down atoms into charged particles. As they zip around, those particles generate magnetic fields, which then guide the particles’ movements. This chaotic interaction knits a scrambled mess of magnetic field lines that, like rubber bands, store more and more energy as they’re stretched and twisted.

***

"More recently, observations from NASA’s magnetospheric satellites identified this speedier reconnection happening even closer to home, in Earth’s own magnetic field. Those observations, along with evidence from decades of computer simulations, confirm this “fast” reconnection rate: In more energetic plasmas, reconnection occurs at roughly 10% of the speed at which magnetic fields propagate — orders of magnitude faster than Sweet and Parker’s theory predicts.

"The 10% reconnection rate is observed so universally that many scientists consider it “God’s given number,” said Alisa Galishnikova, a researcher at Princeton. But invoking the divine does little to explain what’s making reconnection so fast.

***

"The first paper, published in Communications Physics, describes how the voltage induces a magnetic field that draws electrons away from the center of the two colliding magnetic regions. That diversion produces a vacuum that sucks in new field lines and pinches them in the center, allowing the magnetic slingshot to form more quickly.

“'That picture was missed … [but] it was staring at us in the face,” said Jim Drake, a plasma physicist at the University of Maryland. “This is the first convincing argument I’ve ever seen.”

"In the second paper, published in Physical Review Letters, Liu and his undergraduate research assistant Matthew Goodbred describe how the same vacuum effect emerges in extreme plasmas containing different ingredients. Around black holes, for example, plasmas are thought to consist of electrons and equally massive positrons, so the Hall effect no longer applies. Yet, “magically, reconnection is still working in a similar way,” Liu said. The researchers propose that within these stronger magnetic fields, most of the energy is spent accelerating particles rather than heating them — again creating a pressure depletion that yields the divine 10% rate.

“'It’s a major milestone theoretically,” said Lorenzo Sironi, a theoretical astrophysicist at Columbia University who works on computer simulations of high-energy plasma jets. “This gives us confidence … that what we’re seeing in our simulations is not crazy.”

***

"Now, scientists hope theoretical advances such as Liu’s will lead to models of magnetic reconnection that more accurately reflect nature. But while his theory aims to settle the reconnection-rate problem, it does not explain why some field lines collide and trigger reconnection but not others. It also doesn’t describe how the outflowing energy is divvied up into jets, heat and cosmic rays — or how any of this works in three dimensions and on larger scales. Still, Liu’s work shows how, under the right circumstances, magnetic reconnection can be efficient enough to drive ephemeral but violent celestial outbursts."

Comment: we are back to dhw's question, why did God make the universe so big and complex? We are still trying to understand the complexity As for the 'why' question. God always has His reasons. This work is poking into just that.