Strange particles observed by an experiment in Antarctica could be evidence of an alternative reality where everything is upside down.
Category: cosmology – Page 315
:oooo.
Past cosmological and astrophysical observations suggest that over one quarter of the universe’s energy density is made up of a non-conventional type of matter known as dark matter. This type of matter is believed to be composed of particles that do not absorb, emit or reflect light, and thus cannot be observed directly using conventional detection methods.
Researchers worldwide have carried out studies aimed at detecting dark matter in the universe, yet so far, none of them has been successful. Even the preferred candidate for dark matter, weakly interacting massive particles (WIMPs), have not yet been observed experimentally.
The China Dark Matter Experiment (CDEX) collaboration, a large team of researchers at Tsinghua University and other universities in China, has recently conducted a search for a different possible dark matter candidate known as the dark photon. While the search was unsuccessful, their paper, published in Physical Review Letters, identifies new constraints on a dark photon parameter that could inform future studies.
Could be made into a generator of some kind :3.
One of the strangest effects to arise from the quantum nature of the universe is the Casimir force. This pushes two parallel conducting plates together when they are just a few dozen nanometres apart.
At these kinds of scales, the Casimir force can dominate and engineers are well aware of its unwanted effects. One reason why microelectromechanical machines have never reached their original promise is the stiction that Casimir forces can generate.
On the other hand, many engineers hope to exploit the Casimir force. Various theoretical models predict that the force should be repulsive between objects of certain shapes, a phenomenon that could prevent stiction.
A neutron star is the dead husk of a star more massive than the sun, but not large enough to become a black hole upon its demise. These stars are between 10 and 29 solar masses during their active lifetime. When they exhaust their nuclear fuel and go supernova, all that’s left is the ultra-dense collapsed core. We call that a neutron star.
The wild physics inside a neutron star are down to the incredible mass packed into such a small space. A neutron star might have twice the mass of our sun packed into an object just a few miles across. The crush of gravity contorts and squeezes neutrons into unusual configurations, based on the models developed by scientists studying neutron stars.
Scientists currently believe that neutron stars have layers characterized by different configurations of distorted neutron matter. For whatever reason, researchers have decided to name the various structures after pasta. Near the surface there’s gnocchi, which are round bubble-like neutrons. Go a bit deeper, and the pressure forces neutrons into long tubes called spaghetti. Go further down, and you have sheets of neutrons called lasagna. That’s just the start of the Italian-inspired interior of neutron stars.
O.,o wut!
A key signal for a certain kind of dark matter failed to turn up in a search throughout the Milky Way. Now scientists are disagreeing about what that means.
Education Saturday with Curious Droid.
Far from calm and peaceful, space is a dangerous place with high levels of radiation not only from our sun but from distant supernovas. This is not only dangerous to us but also to the spacecraft themselves with is able to damage the electronics and computers that keep it running and the crew alive in it. So how do they protect the craft and crew with what looks like almost no shielding at all?
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Last year, a global collaboration of scientists made history by unveiling the very first direct image of a black hole. Now, we have a magnificent follow-up — the closest-ever look at a violent jet spewed forth by a supermassive black hole.
In nuclear physics, like much of science, detailed theories alone aren’t always enough to unlock solid predictions. There are often too many pieces, interacting in complex ways, for researchers to follow the logic of a theory through to its end. It’s one reason there are still so many mysteries in nature, including how the universe’s basic building blocks coalesce and form stars and galaxies. The same is true in high-energy experiments, in which particles like protons smash together at incredible speeds to create extreme conditions similar to those just after the Big Bang.
Fortunately, scientists can often wield simulations to cut through the intricacies. A simulation represents the important aspects of one system—such as a plane, a town’s traffic flow or an atom—as part of another, more accessible system (like a computer program or a scale model). Researchers have used their creativity to make simulations cheaper, quicker or easier to work with than the formidable subjects they investigate—like proton collisions or black holes.
Simulations go beyond a matter of convenience; they are essential for tackling cases that are both too difficult to directly observe in experiments and too complex for scientists to tease out every logical conclusion from basic principles. Diverse research breakthroughs—from modeling the complex interactions of the molecules behind life to predicting the experimental signatures that ultimately allowed the identification of the Higgs boson—have resulted from the ingenious use of simulations.
New particles sensitive to the strong interaction might be produced in abundance in the proton-proton collisions generated by the Large Hadron Collider (LHC) – provided that they aren’t too heavy. These particles could be the partners of gluons and quarks predicted by supersymmetry (SUSY), a proposed extension of the Standard Model of particle physics that would expand its predictive power to include much higher energies. In the simplest scenarios, these “gluinos” and “squarks” would be produced in pairs, and decay directly into quarks and a new stable neutral particle (the “neutralino”), which would not interact with the ATLAS detector. The neutralino could be the main constituent of dark matter.
The ATLAS Collaboration has been searching for such processes since the early days of LHC operation. Physicists have been studying collision events featuring “jets” of hadrons, where there is a large imbalance in the momenta of these jets in the plane perpendicular to the colliding protons (“missing transverse momentum,” ETmiss). This missing momentum would be carried away by the undetectable neutralinos. So far, ATLAS searches have led to increasingly tighter constraints on the minimum possible masses of squarks and gluinos.
Is it possible to do better with more data? The probability of producing these heavy particles decreases exponentially with their masses, and thus repeating the previous analyses with a larger dataset only goes so far. New, sophisticated methods that help to better distinguish a SUSY signal from the background Standard Model events are needed to take these analyses further. Crucial improvements may come from increasing the efficiency for selecting signal events, improving the rejection of background processes, or looking into less-explored regions.
Adilson Motter, Northwestern University
After 12 successful seasons, “The Big Bang Theory” has finally come to a fulfilling end, concluding its reign as the longest running multicamera sitcom on TV.
If you’re one of the few who haven’t seen the show, this CBS series centers around a group of young scientists defined by essentially every possible stereotype about nerds and geeks. The main character, Sheldon (Jim Parsons), is a theoretical physicist. He is exceptionally intelligent, but also socially unconventional, egocentric, envious and ultra-competitive. His best friend, Leonard (Johnny Galecki), is an experimental physicist who, although more balanced, also shows more fluency with quantum physics than with ordinary social situations.