wp-plugin-hostgator domain was triggered too early. This is usually an indicator for some code in the plugin or theme running too early. Translations should be loaded at the init action or later. Please see Debugging in WordPress for more information. (This message was added in version 6.7.0.) in /home4/scienrds/scienceandnerds/wp-includes/functions.php on line 6114ol-scrapes domain was triggered too early. This is usually an indicator for some code in the plugin or theme running too early. Translations should be loaded at the init action or later. Please see Debugging in WordPress for more information. (This message was added in version 6.7.0.) in /home4/scienrds/scienceandnerds/wp-includes/functions.php on line 6114Source:https:\/\/www.quantamagazine.org\/the-tiny-physics-behind-immense-cosmic-eruptions-20230515\/#comments<\/a><\/br> 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.<\/p>\n 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<\/a> ejected by exploding stars, the glow of jets from feasting black holes<\/a>, and the constant wind<\/a> blown by the sun.<\/p>\n Despite the phenomenon\u2019s ubiquity, scientists have struggled to understand how it works so efficiently. A recent theory<\/a> proposes that when it comes to solving the mysteries of magnetic reconnection, tiny physics plays a big role. In particular, it explains why some reconnection events are so stupefyingly fast \u2014\u00a0and why the strongest seem to occur at a characteristic speed. Understanding the microphysical details of reconnection could help researchers build better models of these energetic eruptions and make sense of cosmic tantrums.<\/p>\n \u201cSo far, this is the best theory I can see,\u201d said Hantao Ji<\/a>, a plasma physicist at Princeton University who was not involved in the study. \u201cIt\u2019s a big achievement.\u201d<\/p>\n Nearly all known matter in the universe exists in the form of plasma<\/a>, 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\u2019 movements. This chaotic interaction knits a scrambled mess of magnetic field lines that, like rubber bands, store more and more energy as they\u2019re stretched and twisted.<\/p>\n In the 1950s, scientists proposed an explanation for how plasmas eject their pent-up energy, a process that came to be called magnetic reconnection. When magnetic field lines pointing in opposite directions collide, they can snap and cross-connect, launching particles like a double-sided slingshot.<\/p>\n But this idea was closer to an abstract painting than a complete mathematical model. Scientists wanted to understand the details of how the process works \u2014 the events that influence the snapping, the reason why so much energy is unleashed. But the messy interplay of hot gas, charged particles and magnetic fields is tricky to tame mathematically.<\/p>\n The first quantitative theory<\/a>, described in 1957 by the astrophysicists Peter Sweet and Eugene Parker, treats plasmas as magnetized fluids. It suggests that collisions of oppositely charged particles draw in magnetic field lines and set off a runaway chain of reconnection events. Their theory also predicts that this process occurs at a particular rate. The reconnection rates observed in relatively weak, laboratory-forged plasmas match their prediction, as do the rates for smaller jets in the lower layers of the sun\u2019s atmosphere.<\/p>\n But solar flares release energy much more quickly than Sweet and Parker\u2019s theory can account for. By their calculations, those flares should unfurl over months rather than minutes.<\/p>\n More recently, observations from NASA\u2019s magnetospheric satellites<\/a> identified this speedier reconnection happening even closer to home, in Earth\u2019s own magnetic field. Those observations, along with evidence from decades of computer simulations, confirm this \u201cfast\u201d reconnection rate: In more energetic plasmas, reconnection occurs at roughly 10% of the speed at which magnetic fields propagate \u2014 orders of magnitude faster than Sweet and Parker\u2019s theory predicts.<\/p>\n The 10% reconnection rate is observed so universally that many scientists consider it \u201cGod\u2019s given number,\u201d said Alisa Galishnikova<\/a>, a researcher at Princeton. But invoking the divine does little to explain what\u2019s making reconnection so fast.<\/p>\n In the 1990s, physicists turned away from treating plasmas as fluids, which had turned out to be too simplistic. Zoomed in, a magnetized soup is really made up of individual particles. And how those particles interact with one another makes a crucial difference.<\/p>\n \u201cWhen you get to the microscales, the fluid description starts breaking down,\u201d said Amitava Bhattacharjee<\/a>, a plasma physicist at Princeton. \u201cThe [microphysical] picture has things in it that the fluid picture can never capture.\u201d<\/p>\n For the past two decades, physicists have suspected that an electromagnetic phenomenon known as the Hall effect might hold the secret to speedy reconnection: Negatively charged electrons and positively charged ions have different masses, so they travel along magnetic field lines at different speeds. That speed differential generates a voltage between the separated charges.<\/p>\n In 2001, Bhattacharjee and his colleagues showed<\/a> that only models that included the Hall effect yielded appropriately fast reconnection rates. But precisely how that voltage produced the magical 10% remained a mystery. \u201cIt did not show us the \u2018how\u2019 and \u2018why,\u2019\u201d said Yi-Hsin Liu<\/a>, a plasma physicist at Dartmouth College.<\/p>\n<\/div>\n <\/br><\/br><\/br><\/p>\n
\nThe Tiny Physics Behind Immense Cosmic Eruptions<\/br>
\n2023-05-16 21:58:06<\/br><\/p>\nFumbling With Fluids<\/strong><\/h2>\n
God\u2019s Number<\/strong><\/h2>\n