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Category: physics – Page 112

Physicists in West Virginia have announced a potential breakthrough that could help upend a longstanding constraint imposed by the first law of thermodynamics.

The discovery, involving how energy is converted in plasmas in space, was described in new research published in the journal Physical Review Letters, and could potentially require scientists to have to rethink how plasmas are heated both in the lab and in space.

The first law of thermodynamics, an expression of the law of conservation of energy albeit styled with relation to thermodynamic processes, conveys that the total energy within a system will remain constant, but that it can be converted from one form of energy into another. More simply, the idea is commonly expressed as “energy can neither be created or destroyed.”

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Atomic nuclei take a range of shapes, from spherical (like a basketball) to deformed (like an American football). Spherical nuclei are often described by the motion of a small fraction of the protons and neutrons, while deformed nuclei tend to rotate as a collective whole.

A third kind of motion has been proposed since the 1950s. In this motion, known as nuclear vibration, fluctuate about an average shape. Scientists recently investigated cadmium-106 using a technique called Coulomb excitation to probe its . They found clear experimental evidence that the vibrational description fails for this isotope’s nucleus. This finding is counter to the expected results.

Research published in Physics Letters B builds on a long quest to understand the transition between spherical and deformed . This transition often includes vibrational motion as an intermediate step. The new result suggests that may need to revise the long-standing paradigm describing how this transition occurs.

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Recently, a research team led by Prof. Guo Guangcan from the University of Science and Technology of China (USTC) constructed a non-Hermiticity (NH) synthetic orbital angular momentum (OAM) dimension in a degenerate optical cavity and observed the exceptional points (EPs). This study was published in Science Advances.

In topological physics, the NH systems depict open systems with complex spectra. Exceptional points are one of the unique features of NH systems. To study EPs, the team had constructed synthetic one-dimensional lattices and established topological simulation platform in a degenerate optical cavity. Based on this platform, an additional pseudomomentum was introduced as a parameter to construct the Dirac point in the two-dimensional momentum space. A pair of EPs can be obtained by introducing non-Hermitian perturbation around the Dirac point.

The detection of complex energy spectra in NH systems can be troublesome for traditional means. The research group developed a method which is referred to as wave front angle–resolved band structure spectroscopy to investigate complex energy spectra based on synthetic OAM. Using this method, the team not only detected EPs in momentum space, but also the key features of EPs like bulk Fermi arcs, parity-time symmetry-breaking transition, energy swapping and half-integer band windings.

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Physics progresses by breaking our intuitions, but we’re now at a point where further progress may require us to do away with the most intuitive and seemingly fundamental concepts of all—space and time.

Continue reading “What If Space And Time Are NOT Real?” | >

Simulations show that nonlinear spacetime dynamics manifest in the postmerger gravitational-wave signal of binary black hole coalescence.

“Spacetime tells matter how to move; matter tells spacetime how to curve.” This statement by physicist John Wheeler captures a defining feature of general relativity: its prediction of nonlinear spacetime dynamics. Such nonlinear evolution should be most evident in energetic spacetime events such as merging black holes, prompting the question of whether we can test for it using observations of gravitational waves emitted during such mergers. Two independent teams, led by Keefe Mitman at the California Institute of Technology [1] and Mark Ho-Yeuk Cheung at Johns Hopkins University in Maryland [2], show that this is the case. Using numerical simulations, they show the presence of nonlinearity in postmerger gravitational-wave signals.

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A pair of worlds that are just around the corner in cosmic terms look to be in the right spot to potentially host life as we know it.

A report in the February issue of the journal Astronomy and Astrophysics details the discovery of two exoplanets the orbit the red M-dwarf star GJ (or Gliese) 1002 in its habitable zone and are not far off from the mass of Earth.

These two characteristics top the list of things that make another planet worth getting excited about in terms of the odds it might have some sort of critters or even just primitive microorganisms hanging out.

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