Almost two thirds of our universe is made up of dark energy. It is invisibly interwoven with the empty space, and forces the universe to expand at an ever-increasing speed. This discovery, which two teams published simultaneously in 1998, was nothing short of a sensation. Nobody yet knows what is behind dark energy.
When a star is burned out and its time has come, it explodes in a supernova. Type 1a supernovae are particularly interesting for astronomers. They only arise in binary systems in which one star is a white dwarf and the other a red giant that is in a phase of expansion. The red giant’s mass flows to the white dwarf until this star reaches its maximum mass limit, which was already predicted by Chandrasekhar Subrahmanyan at the end of the 1930s; he was awarded the 1983 Nobel Prize for it. Consequently, the white dwarf explodes in a type 1a supernova. As the brightness of these explosions is physically always the same, observing the apparent brightness of supernovae allows astronomers to deduce their distance. A supernova occurs in every galaxy approximately once every 500 years. The gigantic universe has around ten type 1a supernovae every minute, however. One incredible feat achieved by the 2011 Laureates was detecting these supernovae at a distance of more than five billion light years, estimating their age, subtracting their signals from the vast quantity of digital data in order to record their luminosity. The other one was to not cast doubt on their own results: “Adam, did you do wrong?” Schmidt asked his colleague Adam Riess, when the latter showed him a diagram of his first measurements.
Most physicists consider the source of the dark energy to be the vacuum, because it is here that matter and energy continuously convert into each other at almost infinite speed - as the laws of quantum physics suggest. The energy which the vacuum can theoretically obtain through these fluctuations is less than the dark energy by the unimaginably large factor of 10 to the power of 122, however. Where are the gaps between theory and observation? Does the dark energy - albeit with opposite sign - correspond to the cosmological constant that Einstein had introduced into his equations, in order to not have to abandon his belief in a static universe? Or is it not constant at all, but originates from temporary force fields? If, as some theoreticians believe, the early universe experienced a sudden expansion resulting in an enormous, temporary increase in its energy density - could something similar be occurring now? And could this explain dark energy? These questions revolve around the greatest physics mystery facing us today. The fine line between speculation and science which they reveal is what makes them so fascinating for a dialogue between young scientists and Nobel Laureates.The radiating beginning of the world
Jan Keese | idw
ICTM Conference 2017: Production technology for turbomachine manufacturing of the future
16.11.2016 | Fraunhofer-Institut für Produktionstechnologie IPT
Innovation Day Laser Technology – Laser Additive Manufacturing
01.11.2016 | Laser Zentrum Hannover e.V.
In recent years, lasers with ultrashort pulses (USP) down to the femtosecond range have become established on an industrial scale. They could advance some applications with the much-lauded “cold ablation” – if that meant they would then achieve more throughput. A new generation of process engineering that will address this issue in particular will be discussed at the “4th UKP Workshop – Ultrafast Laser Technology” in April 2017.
Even back in the 1990s, scientists were comparing materials processing with nanosecond, picosecond and femtosesecond pulses. The result was surprising:...
Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...
A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.
Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...
In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.
“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...
The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.
The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...
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