‘Spin’ is a fundamental quality of fundamental particles like the electron, invoking images of a tiny sphere revolving rapidly on its axis like a planet in a shrunken solar system.
Only it isn’t. It can’t. For one thing, electrons aren’t spheres of matter but points described by the mathematics of probability.
But California Institute of Technology philosopher of physics Charles T. Sebens argues such a particle-based approach to one of the most accurate theories in physics might be misleading us.
The dynamics of electrons submitted to voltage pulses in a thin semiconductor layer is investigated using a kinetic approach based on the solution of the electron Boltzmann equation using particle-in-cell/Monte Carlo collision simulations. The results showed that due to the fairly high plasma density, oscillations emerge from a highly nonlinear interaction between the space-charge field and the electrons. The voltage pulse excites electron waves with dynamics and phase-space trajectories that depend on the doping level. High-amplitude oscillations take place during the relaxation phase and are subsequently damped over time-scales in the range 100 – 400 fs and decrease with the doping level. The power spectra of these oscillations show a high-energy band and a low-energy peak that were attributed to bounded plasma resonances and to a sheath effect. The high-energy THz domain reduces to sharp and well-defined peaks for the high doping case. The radiative power that would be emitted by the thin semiconductor layer strongly depends on the competition between damping and radiative decay in the electron dynamics. Simulations showed that higher doping level favor enhanced magnitude and much slower damping for the high-frequency current, which would strongly enhance the emitted level of THz radiation.
Since the focus on Martian exploration ramped up in the mid-1990s, most of the familiarity with the Entry, Descent, and Landing (EDL) sequence of landers and rovers to the surface of other planets has taken place against the backdrop of Mars.
But when NASA‘s upcoming Dragonfly mission arrives at Titan for its own EDL, it will experience a starkly different set of conditions that both add new complexity and ease some structural considerations for the system that will deliver the rotorcraft into Titan’s atmosphere.
Year 2022, this basically could shield the earth or Mars from solar radiation if we needed it. 😗
First experimental measurement of pure electron outflows associated with magnetic reconnection driven by electron dynamics in laser-produced plasmas.
Magnetic reconnections in laser-produced plasmas have been investigated in order to better understand the microscopic electron dynamics, which are relevant to space and astrophysical phenomena. Osaka University scientists, in collaboration with researchers at the National Institute for Fusion Science and other universities, have reported the direct measurements of pure electron outflows relevant to magnetic reconnection using a high-power laser, Gekko XII, at the Institute of Laser Engineering, Osaka University in Japan. Their findings will be published today (June 30, 2022) in Springer Nature, Scientific Reports.
Established in 2011, <em>Scientific Report</em>s is a peer-reviewed open-access scientific mega journal published by Nature Portfolio, covering all areas of the natural sciences. In September 2016, it became the largest journal in the world by number of articles, overtaking <em>PLOS ON</em>E.
A study published by The Planetary Science Journal in 2020 suggests that Psyche is made almost entirely of iron and nickel. This metallic composition sets it apart from other asteroids that are usually comprised of rock or ice, and could suggest it was originally part of a planetary core. That would not only represent a momentous discovery, it’s key to Psyche’s potential astronomical value: NASA scientist Lindy Elkins-Tanton calculated that the iron in the asteroid alone could be worth as much as $10 quintillion, which is $10,000,000,000,000,000,000 (yes, a 20-figure sum). For context, the entire global economy is worth roughly $110 trillion as of writing. However, more recent research out of the University of Arizona suggests that the asteroid might not be as metallic or dense as once thought. Psyche could actually be closer to a rubble pile, rather than an exposed planetary core, the research claims. If true, this would devalue the asteroid. NASA’s upcoming mission should settle the debate about Pysche’s composition for once and all.
Of course, Psyche isn’t the only valuable rock in space. NASA has previously said the belt of asteroids between Mars and Jupiter holds mineral wealth equivalent to about $100 billion for every individual on Earth. Mining the precious metals within each asteroid and successfully getting them back down to earth is the hard part. Then you have the whole supply and demand conundrum that could drive the price of specific metals up or down. We’ll leave the complexities of space mining for another day.
If Psyche is, in fact, the leftover core of a planet that never properly formed, it could reveal secrets about Earth’s own core. The interior of terrestrial planets is normally hidden beneath the mantle and crust, but Psyche has no such outer layers. The asteroid’s mantle and crust were likely stripped away by multiple violent collisions during our solar system’s early formation. By examining Psyche, we can further understand how Earth’s core came to be. The mission could also provide insights into the formation of our solar system and the planetary systems around other stars.
Our lifespans might feel like a long time by human standards, but to the Earth it’s the blink of an eye. Even the entirety of human history represents a tiny slither of the vast chronology for our planet. We often think about geological time when looking back into the past, but today we look ahead. What might happen on our planet in the next billion years?
Written and presented by Prof David Kipping, edited by Jorge Casas.
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The European Space Agency (ESA) is using a unique robotic arm to bring back Martian samples to Earth, according to a statement by the organization published on Thursday (Jan .26).
What is the ‘Sample Transfer Arm?’
ESA/YouTube.
“The mission to return Martian samples back to Earth will see a European 2.5 meter-long robotic arm pick up tubes filled with precious soil from Mars and transfer them to a rocket for a historic interplanetary delivery,” noted the press release.
The whole world has been awestruck by the magnificent images produced by NASA’s James Webb Space Telescope. Webb has already turned astronomy on its head and renewed debate about how the cosmos first formed and evolved. But there were years of delays in its development that frustrated both researchers and the public at large.
So, at the 241st meeting of the American Astronomical Society (AAS) this month in Seattle, a major topic of discussion was lessons learned from Webb’s extended gestation period. And, specifically, how to take this hard-won experience and use it to proceed with the next generation of revolutionary space telescopes.
NASA and the astronomical community at large have already started initial planning on the next generation of space telescopes. Three new large space observatories could all see operation by 2045.
The standard model of particle physics tells us that most particles we observe are made up of combinations of just six types of fundamental entities called quarks. However, there are still many mysteries, one of which is an exotic, but very short-lived, Lambda resonance known as Λ(1405). For a long time, it was thought to be a particular excited state of three quarks—up, down, and strange—and understanding its internal structure may help us learn more about the extremely dense matter that exists in neutron stars.
Investigators from Osaka University were part of a team that has now succeeded in synthesizing Λ(1405) for the first time by combining a K- meson and a proton and determining its complex mass (mass and width). The K− meson is a negatively charged particle containing a strange quark and an up antiquark. The much more familiar proton that makes up the matter that we are used to has two up quarks and a down quark. The researchers showed that Λ(1405) is best thought of as a temporary bound state of the K- meson and the proton, as opposed to a three-quark excited state.
In their study published recently in Physics Letters B, the group describes the experiment they carried out at the J-PARC accelerator. K− mesons were shot at a deuterium target, each of which had one proton and one neutron. In a successful reaction, a K− meson kicked out the neutron, and then merged with the proton to produce the desired Λ(1405).