The planet Earth will die – if not before, then when the Sun collapses. This is going to happen in approximately seven billion years. In the universe however the death of suns and planets is an everyday occurance and our solar system partly consists of their remnants.
The end of stars – suns – rich in mass is often a neutron star. These “stars' liches“ demonstrate a high density, in which atoms are extremely compressed. Such neutron stars are no bigger than a small town, but heavier than our sun, as physicist PD Dr. Axel Maas of the Jena University (Germany) points out. He adds: “The atomic nuclei are very densely packed.“ Compared to atoms, like water, the nuclei of neutron stars are as tightly packed as a bus with 1.000 passengers crowded together in comparison to a bus with only the driver on board. In these densely packed atomic nuclei, so-called “nuclear forces“ are at work. They keep the neutron star together and are responsible for its “eternal life“ – and for the last 35 years the strong nuclear interactions were amongst the greatest challenges of theoretical physics.
Together with colleagues from the Universities of Jena and Darmstadt (both Germany) Axel Maas has succeeded in simulating the strong atomic nuclear interactions to enable its calculability while at the same time preserving the typical characteristics of a neutron star. “It is the first theory for such a tight package,“ the Jena Physicist says. Previously simulations trying to specify the matter inside of neutron stars collapsed far too much in size and yielded the wrong properties time and again – even on the most powerful computers. “These simulations didn't work because there are too many atomic nuclei,“ Maas explains the problem, whose solution the world of physics has come closer to due to the calculations of the Jena researchers. To get there, the scientists did so many calculations at the Loewe Center for Science Computing (CSC) in Frankfurt, that it would have taken a single PC approximately 2.500 years to do the same.
“We weren't able to solve the initial problem either,“ Axel Maas concedes, as algorithms are not (yet) powerful enough. However, the Jena physicist who had been researching this problem since 2007 and his colleagues “reached a new level of quality“. They found a “modification of the theory for such a tight package“, Maas says. And thus they enabled nuclear material to be simulated. Most characteristics of the neutron star are being preserved with the Jena method, but now they enabled its calculability.The team accomplished this big step forward by intelligently modifying the nuclear forces and by solving the stacking problem of the atoms. That they were at the same time ’cheating a bit‘, the physicists freely admit. However, Maas firmly believes: “We found the best possible shortcut“. Now they know “what is relevant for the original simulation“.
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Plants and algae use the enzyme Rubisco to fix carbon dioxide, removing it from the atmosphere and converting it into biomass. Algae have figured out a way to increase the efficiency of carbon fixation. They gather most of their Rubisco into a ball-shaped microcompartment called the pyrenoid, which they flood with a high local concentration of carbon dioxide. A team of scientists at Princeton University, the Carnegie Institution for Science, Stanford University and the Max Plank Institute of Biochemistry have unravelled the mysteries of how the pyrenoid is assembled. These insights can help to engineer crops that remove more carbon dioxide from the atmosphere while producing more food.
A warming planet
Our brains house extremely complex neuronal circuits, whose detailed structures are still largely unknown. This is especially true for the so-called cerebral cortex of mammals, where among other things vision, thoughts or spatial orientation are being computed. Here the rules by which nerve cells are connected to each other are only partly understood. A team of scientists around Moritz Helmstaedter at the Frankfiurt Max Planck Institute for Brain Research and Helene Schmidt (Humboldt University in Berlin) have now discovered a surprisingly precise nerve cell connectivity pattern in the part of the cerebral cortex that is responsible for orienting the individual animal or human in space.
The researchers report online in Nature (Schmidt et al., 2017. Axonal synapse sorting in medial entorhinal cortex, DOI: 10.1038/nature24005) that synapses in...
Whispering gallery mode (WGM) resonators are used to make tiny micro-lasers, sensors, switches, routers and other devices. These tiny structures rely on a...
Using ultrafast flashes of laser and x-ray radiation, scientists at the Max Planck Institute of Quantum Optics (Garching, Germany) took snapshots of the briefest electron motion inside a solid material to date. The electron motion lasted only 750 billionths of the billionth of a second before it fainted, setting a new record of human capability to capture ultrafast processes inside solids!
When x-rays shine onto solid materials or large molecules, an electron is pushed away from its original place near the nucleus of the atom, leaving a hole...
For the first time, physicists have successfully imaged spiral magnetic ordering in a multiferroic material. These materials are considered highly promising candidates for future data storage media. The researchers were able to prove their findings using unique quantum sensors that were developed at Basel University and that can analyze electromagnetic fields on the nanometer scale. The results – obtained by scientists from the University of Basel’s Department of Physics, the Swiss Nanoscience Institute, the University of Montpellier and several laboratories from University Paris-Saclay – were recently published in the journal Nature.
Multiferroics are materials that simultaneously react to electric and magnetic fields. These two properties are rarely found together, and their combined...
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