KREUZADER (Posts tagged physics)

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XENON1T Experimental data establishes most stringent limit on dark matter “ Experimental results from the XENON1T dark matter detector limit the effective size of dark matter particles to 4.1X10-47 square centimeters - one-trillionth of...

XENON1T Experimental data establishes most stringent limit on dark matter

Experimental results from the XENON1T dark matter detector limit the effective size of dark matter particles to 4.1X10-47 square centimeters - one-trillionth of one-trillionth of a centimeter squared - the most stringent limit yet determined for dark matter as established by the world’s most sensitive detector.

The results, presented Monday in a seminar in Italy at the Gran Sasso Underground Laboratory (LNGS), were produced using an active target volume of 1,300 kilograms of Xenon, the first search for dark matter that has monitored the equivalent of one ton of xenon for an entire year.

Source: spacedaily.com
dark matter physics
The inside of a proton endures more pressure than anything else we’ve seen ““It’s really the highest pressure we have ever seen,” says physicist Volker Burkert, a coauthor of the study, published in the May 17 Nature. Protons break the pressure...

The inside of a proton endures more pressure than anything else we’ve seen

“It’s really the highest pressure we have ever seen,” says physicist Volker Burkert, a coauthor of the study, published in the May 17 Nature. Protons break the pressure record set by neutron stars, the incredibly dense dead stars that can form when a massive star explodes and its core collapses, squeezing more mass than the sun’s into a remnant the size of a city.

The pressure in the proton’s center averages a million trillion trillion times the strength of Earth’s atmospheric pressure, report Burkert and colleagues, from Thomas Jefferson National Accelerator Facility in Newport News, Va. That’s around 10 times the pressure found inside a neutron star. Previously, scientists had theoretically predicted that such pressures might occur inside protons, but the new result is the first experimental proton pressure gauge.

Source: sciencenews.org
physics
Weak charge of the proton measured “Subatomic particles interact through four fundamental forces. However, only two of these forces have effects on macroscopic scales: gravity keeps us grounded on Earth, and electromagnetism causes lightning on...

Weak charge of the proton measured

Subatomic particles interact through four fundamental forces. However, only two of these forces have effects on macroscopic scales: gravity keeps us grounded on Earth, and electromagnetism causes lightning on stormy days. We are not directly influenced by the other two forces — the weak and strong forces. Similarly, it is generally known that mass is at the root of gravitational interactions and that electric charges and magnetic moments are central to electromagnetism. But the physical properties that describe the strength of weak and strong interactions, known as weak and colour charges, respectively, are less familiar. In a paper in Nature, the Jefferson Lab Qweak Collaboration1 reports the first high-precision measurement of the weak charge of the proton, which sets tight constraints on physics that cannot be described by current theories.

Source: nature.com
physics
Yale physicists find signs of a time crystal “The discovery means there are now new puzzles to solve, in terms of how time crystals form in the first place. Ordinary crystals such as salt or quartz are examples of three-dimensional, ordered spatial...

Yale physicists find signs of a time crystal

The discovery means there are now new puzzles to solve, in terms of how time crystals form in the first place.

Ordinary crystals such as salt or quartz are examples of three-dimensional, ordered spatial crystals. Their atoms are arranged in a repeating system, something scientists have known for a century.

Time crystals, first identified in 2016, are different. Their atoms spin periodically, first in one direction and then in another, as a pulsating force is used to flip them. That’s the “ticking.” In addition, the ticking in a time crystal is locked at a particular frequency, even when the pulse flips are imperfect.

Scientists say that understanding time crystals may lead to improvements in atomic clocks, gyroscopes, and magnetometers, as well as aid in building potential quantum technologies. The U.S. Department of Defense recently announced a program to fund more research into time crystal systems.

Source: news.yale.edu
physics
Taming the multiverse: Stephen Hawking’s final theory about the big bang “In their new paper, Hawking and Hertog say this account of eternal inflation as a theory of the big bang is wrong. “The problem with the usual account of eternal inflation is...

Taming the multiverse: Stephen Hawking’s final theory about the big bang

In their new paper, Hawking and Hertog say this account of eternal inflation as a theory of the big bang is wrong. “The problem with the usual account of eternal inflation is that it assumes an existing background universe that evolves according to Einstein’s theory of general relativity and treats the quantum effects as small fluctuations around this,” said Hertog. “However, the dynamics of eternal inflation wipes out the separation between classical and quantum physics. As a consequence, Einstein’s theory breaks down in eternal inflation.”

“We predict that our universe, on the largest scales, is reasonably smooth and globally finite. So it is not a fractal structure,” said Hawking.

Source: cam.ac.uk
cosmology physics stephen hawking
Machine Learning’s ‘Amazing’ Ability to Predict Chaos “In a series of results reported in the journals Physical Review Letters and Chaos, scientists have used machine learning — the same computational technique behind recent successes in artificial...

Machine Learning’s ‘Amazing’ Ability to Predict Chaos

In a series of results reported in the journals Physical Review Letters and Chaos, scientists have used machine learning — the same computational technique behind recent successes in artificial intelligence — to predict the future evolution of chaotic systems out to stunningly distant horizons. The approach is being lauded by outside experts as groundbreaking and likely to find wide application.

[…]

The findings come from veteran chaos theorist Edward Ott and four collaborators at the University of Maryland. They employed a machine-learning algorithm called reservoir computing to “learn” the dynamics of an archetypal chaotic system called the Kuramoto-Sivashinsky equation. The evolving solution to this equation behaves like a flame front, flickering as it advances through a combustible medium. The equation also describes drift waves in plasmas and other phenomena, and serves as “a test bed for studying turbulence and spatiotemporal chaos,” said Jaideep Pathak, Ott’s graduate student and the lead author of the new papers.

Source: quantamagazine.org
mathematics physics machine learning
Stephen Hawking’s last paper: “ The usual theory of inflation breaks down in eternal inflation. We derive a dual description of eternal inflation in terms of a deformed CFT located at the threshold of eternal inflation. The partition function gives...

Stephen Hawking’s last paper:

The usual theory of inflation breaks down in eternal inflation. We derive a dual description of eternal inflation in terms of a deformed CFT located at the threshold of eternal inflation. The partition function gives the amplitude of different geometries of the threshold surface in the no-boundary state. Its local and global behavior in dual toy models shows that the amplitude is low for surfaces which are not nearly conformal to the round three-sphere and essentially zero for surfaces with negative curvature. Based on this we conjecture that the exit from eternal inflation does not produce an infinite fractal-like multiverse, but is finite and reasonably smooth.
Source: arxiv.org
physics cosmology stephen hawking astrophysics
“The search for the full theory of quantum gravity has been stymied by the fact that gravity’s quantum properties never seem to manifest in actual experience. Physicists never get to see how Einstein’s description of the smooth space-time continuum,...

The search for the full theory of quantum gravity has been stymied by the fact that gravity’s quantum properties never seem to manifest in actual experience. Physicists never get to see how Einstein’s description of the smooth space-time continuum, or Bronstein’s quantum approximation of it when it’s weakly curved, goes wrong.

The problem is gravity’s extreme weakness. Whereas the quantized particles that convey the strong, weak and electromagnetic forces are so powerful that they tightly bind matter into atoms, and can be studied in tabletop experiments, gravitons are individually so weak that laboratories have no hope of detecting them. To detect a graviton with high probability, a particle detector would have to be so huge and massive that it would collapse into a black hole. This weakness is why it takes an astronomical accumulation of mass to gravitationally influence other massive bodies, and why we only see gravity writ large.

Source: quantamagazine.org
physics
Synthetic electromagnetic knot in a three-dimensional skyrmion“Classical electromagnetism and quantum mechanics are both central to the modern understanding of the physical world and its ongoing technological development. Quantum simulations of...

Synthetic electromagnetic knot in a three-dimensional skyrmion

Classical electromagnetism and quantum mechanics are both central to the modern understanding of the physical world and its ongoing technological development. Quantum simulations of electromagnetic forces have the potential to provide information about materials and systems that do not have conveniently solvable theoretical descriptions, such as those related to quantum Hall physics, or that have not been physically observed, such as magnetic monopoles. However, quantum simulations that simultaneously implement all of the principal features of classical electromagnetism have thus far proved elusive. We experimentally realize a simulation in which a charged quantum particle interacts with the knotted electromagnetic fields peculiar to a topological model of ball lightning. These phenomena are induced by precise spatiotemporal control of the spin field of an atomic Bose-Einstein condensate, simultaneously creating a Shankar skyrmion—a topological excitation that was theoretically predicted four decades ago but never before observed experimentally. Our results reveal the versatile capabilities of synthetic electromagnetism and provide the first experimental images of topological three-dimensional skyrmions in a quantum system.

Source: advances.sciencemag.org
physics lightning
lordtableshark
astronomyblog

IceCube ( IceCube Neutrino Observatory)

IceCube, the South Pole neutrino observatory, is a cubic-kilometer particle detector made of Antarctic ice and located near the Amundsen-Scott South Pole Station. It is buried beneath the surface, extending to a depth of about 2,500 meters. A surface array, IceTop, and a denser inner subdetector, DeepCore, significantly enhance the capabilities of the observatory, making it a multipurpose facility.

IceCube is the first gigaton neutrino detector ever built and was primarily designed to observe neutrinos from the most violent astrophysical sources in our universe. Neutrinos, almost massless particles with no electric charge, can travel from their sources to Earth with essentially no attenuation and no deflection by magnetic fields.

The in-ice component of IceCube consists of 5,160 digital optical modules (DOMs), each with a ten-inch photomultiplier tube and associated electronics. The DOMs are attached to vertical “strings,” frozen into 86 boreholes, and arrayed over a cubic kilometer from 1,450 meters to 2,450 meters depth. The strings are deployed on a hexagonal grid with 125 meters spacing and hold 60 DOMs each. The vertical separation of the DOMs is 17 meters.

Eight of these strings at the center of the array were deployed more compactly, with a horizontal separation of about 70 meters and a vertical DOM spacing of 7 meters. This denser configuration forms the DeepCore subdetector, which lowers the neutrino energy threshold to about 10 GeV, creating the opportunity to study neutrino oscillations.

IceTop consists of 81 stations located on top of the same number of IceCube strings. Each station has two tanks, each equipped with two downward facing DOMs. IceTop, built as a veto and calibration detector for IceCube, also detects air showers from primary cosmic rays in the 300 TeV to 1 EeV energy range. The surface array measures the cosmic-ray arrival directions in the Southern Hemisphere as well as the flux and composition of cosmic rays.

Developments in neutrino astronomy have been driven by the search for the sources of cosmic rays, leading at an early stage to the concept of a cubic-kilometer neutrino detector. Cosmic rays, which consist mainly of protons, are the highest energy particles ever observed, with energies over a million times those reached by today’s particle accelerators on Earth.

AMANDA, the Antarctic Muon and Neutrino Detector Array, was built as a proof of concept in the mid 1990s and demonstrated that the extremely clear Antarctic ice was suitable for detecting energetic neutrinos. IceCube, the only cubic-kilometer neutrino detector constructed to date, was completed in December 2010, only six years after the deployment of the first string at the South Pole.

Neutrinos are not observed directly, but when they happen to interact with the ice they produce electrically charged secondary particles that in turn emit Cherenkov light, as a result of traveling through the ice faster than light travels in ice.

The IceCube sensors collect this light, which is subsequently digitized and time stamped. This information is sent to computers in the IceCube Lab on the surface, which converts the messages from individual DOMs into light patterns that reveal the direction and energy of muons and neutrinos.

The IceCube Neutrino Observatory was built under a National Science Foundation (NSF) Major Research Equipment and Facilities Construction grant, with assistance from partner funding agencies around the world. The NSF Office of Polar Programs supports the project with a Maintenance and Operations (M&O) grant. The University of Wisconsin–Madison is the lead institution, coordinating data-taking and M&O activities. The international IceCube Collaboration, with more than 40 institutions worldwide, is responsible for the scientific research program.

Source: icecube.wisc.edu Images: iceCube/NSF,Mike Lucibella, Sven Lidstrom, Jim Haugen, B. Gudbjartsson.

physics astronomy neutrino
Physicists plan antimatter’s first outing — in a van “Antimatter is notoriously volatile, but physicists have learned to control it so well that they are now starting to harness it as a tool for the first time. In a project that began last month,...

Physicists plan antimatter’s first outing — in a van

Antimatter is notoriously volatile, but physicists have learned to control it so well that they are now starting to harness it as a tool for the first time. In a project that began last month, researchers will transport antimatter by truck and then use it to study the strange behaviour of rare radioactive nuclei. The work aims to provide a better understanding of fundamental processes inside atomic nuclei and to help astrophysicists to learn about the interiors of neutron stars, which contain the densest form of matter in the Universe.

Source: nature.com
physics antimatter
Physicists create new form of light“In a paper published today in the journal Science, the team, led by Vladan Vuletic, the Lester Wolfe Professor of Physics at MIT, and Professor Mikhail Lukin from Harvard University, reports that it has observed...

Physicists create new form of light

In a paper published today in the journal Science, the team, led by Vladan Vuletic, the Lester Wolfe Professor of Physics at MIT, and Professor Mikhail Lukin from Harvard University, reports that it has observed groups of three photons interacting and, in effect, sticking together to form a completely new kind of photonic matter.

In controlled experiments, the researchers found that when they shone a very weak laser beam through a dense cloud of ultracold rubidium atoms, rather than exiting the cloud as single, randomly spaced photons, the photons bound together in pairs or triplets, suggesting some kind of interaction — in this case, attraction — taking place among them.

While photons normally have no mass and travel at 300,000 kilometers per second (the speed of light), the researchers found that the bound photons actually acquired a fraction of an electron’s mass. These newly weighed-down light particles were also relatively sluggish, traveling about 100,000 times slower than normal noninteracting photons.

uhhh… to quote I.I. Rabi - “who ordered that?”

Source: news.mit.edu
physics
Optical rectification through an Al2O3 based MIM passive rectenna at 28.3 THz“Harevesting energy from waste heat which fluctuates between, approximately, 250 K and 1500 K, i.e., peaking at 2–11 μm, could be a game changer in terms of tapping on to...

Optical rectification through an Al2O3 based MIM passive rectenna at 28.3 THz

Harevesting energy from waste heat which fluctuates between, approximately, 250 K and 1500 K, i.e., peaking at 2–11 μm, could be a game changer in terms of tapping on to renewable energy sources. However, research in this area has remained elusive due to numerous challenges. We consider waste heat to be an electromagnetic (EM) wave in the mid infrared (IR) frequency range, which can be captured through a resonant antenna and rectified into useful DC through a diode, an arrangement typically known as a rectenna. A bowtie antenna has been optimized for IR field capture and enhancement through EM simulations. At the overlap of the bowtie arms, a metal-insulator-metal (MIM) diode has been realized that can operate at such a high frequency (28.3 THz or 10.6 μm). The choice of a low permittivity insulator (Al2O3) helps metigate [sic] the RC time constant and the diode’s cutoff frequency, whereas the two different work function metals, Au and Ti, facilitate diode operation through tunneling at no applied bias. A custom optical characterization setup employing a 10.6 μm CO2 laser has been used to assess the IR capture and rectification ability of the rectenna device. A polarization dependent voltage output which is well above the noise level and well matched with our calculations, confirms the successful rectenna operation. According to authors’ best knowledge, this is the first demonstration of rectification at 28.3 THz through a MIM diode based rectenna at zero applied bias.

Source: sciencedirect.com
physics energy
“Physicists need to know the neutron’s lifetime in order to calculate the relative abundances of hydrogen and helium that would have been produced during the universe’s first few minutes. The faster neutrons decayed to protons in that period, the...

Physicists need to know the neutron’s lifetime in order to calculate the relative abundances of hydrogen and helium that would have been produced during the universe’s first few minutes. The faster neutrons decayed to protons in that period, the fewer would have existed later to be incorporated into helium nuclei. “That balance of hydrogen and helium is first of all a very sensitive test of the dynamics of the Big Bang,” said Geoffrey Greene, a nuclear physicist at the University of Tennessee and Oak Ridge National Laboratory, “but it also tells us how stars are going to form over the next billions of years,” since galaxies with more hydrogen form more massive, and eventually more explosive, stars. Thus, the neutron lifetime affects predictions of the universe’s far future.

Source: quantamagazine.org
physics