Black holes really are holes - objects without a surface - say Drs Christine Done and Marek Gierlinski in a paper accepted for publication in the Monthly Notices of the Royal Astronomical Society. Having an "event horizon" rather than a surface is the property that makes something a black hole but, by definition, its impossible ever to see one directly. However, these new results give direct evidence of the existence of such holes in spacetime.
Drs Done and Gierlinski set out to track down the signatures of event horizons by looking for differences between objects thought to be black holes and collapsed bodies of a different kind that are only slightly less extreme - neutron stars. Any material captured by the strong gravity of either type of object will spiral inwards in much the same way, reaching speeds of up to half the speed of light and transforming some of the immense gravitational energy into X-ray emission. The crucial difference is that, in the case of a black hole, material should simply pour into the hole, taking its remaining energy with it and disappearing forever, whereas with a neutron star material smashes onto the surface, releasing whatever energy is left. As a consequence, the X-ray emissions from neutron stars and black holes should look different.
"The idea is simple in theory, and has been known for a long time, but until now it has been hard to put into practice because the X-ray emission even from a single type of object can show a bewildering variety of properties that are not well understood," says Chris Done.
Dr Chris Done | alfa
Four elements make 2-D optical platform
26.09.2017 | Rice University
The material that obscures supermassive black holes
26.09.2017 | Instituto de Astrofísica de Canarias (IAC)
Controlling electronic current is essential to modern electronics, as data and signals are transferred by streams of electrons which are controlled at high speed. Demands on transmission speeds are also increasing as technology develops. Scientists from the Chair of Laser Physics and the Chair of Applied Physics at Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) have succeeded in switching on a current with a desired direction in graphene using a single laser pulse within a femtosecond ¬¬ – a femtosecond corresponds to the millionth part of a billionth of a second. This is more than a thousand times faster compared to the most efficient transistors today.
Graphene is up to the job
At the productronica trade fair in Munich this November, the Fraunhofer Institute for Laser Technology ILT will be presenting Laser-Based Tape-Automated Bonding, LaserTAB for short. The experts from Aachen will be demonstrating how new battery cells and power electronics can be micro-welded more efficiently and precisely than ever before thanks to new optics and robot support.
Fraunhofer ILT from Aachen relies on a clever combination of robotics and a laser scanner with new optics as well as process monitoring, which it has developed...
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...
19.09.2017 | Event News
12.09.2017 | Event News
06.09.2017 | Event News
26.09.2017 | Life Sciences
26.09.2017 | Physics and Astronomy
26.09.2017 | Information Technology