A new analysis that refutes challenges to the existence of dark matter in certain galaxies appears in an article published this week in the journal Nature. Leading author of the article is Avishai Dekel, professor of physics at the Hebrew University of Jerusalem.
Illustration of computer simulation showing two spiral galaxies combining to form an elliptical galaxy at right.
Accepted cosmological theory postulates that every observable galaxy in the universe (each made up of billions of stars similar to our sun) is embedded in a massive “halo" of dark matter. Though unseen, dark matter can be clearly detected indirectly by observing its tremendous gravitational effects on visible objects.
This common understanding faced a severe challenge when a team of astronomers, writing in Science in 2003, reported a surprising absence of dark matter in one type of galaxy – “elliptical" (rounded) galaxies. Their theory was based on observations that stars located at great distances from the center in such galaxies move at very slow speeds, as opposed to the great speed one would have expected from the heavy gravitational pull exerted by dark matter.
Jerry Barach | alfa
Applicability of dynamic facilitation theory to binary hard disk systems
08.12.2016 | Nagoya Institute of Technology
Will Earth still exist 5 billion years from now?
08.12.2016 | KU Leuven
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,...
16.11.2016 | Event News
01.11.2016 | Event News
14.10.2016 | Event News
08.12.2016 | Life Sciences
08.12.2016 | Physics and Astronomy
08.12.2016 | Materials Sciences