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Category: physics – Page 139

It enables us to make extraordinary leaps of imagination.

We all have to make hard decisions from time to time. The hardest of my life was whether or not to change research fields after my Ph.D., from fundamental physics to climate physics. I had job offers that could have taken me in either direction — one to join Stephen Hawking’s Relativity and Gravitation Group at Cambridge University, another to join the Met Office as a scientific civil servant.

I wrote down the pros and cons of both options as one is supposed to do, but then couldn’t make up my mind at all. Like Buridan’s donkey, I was unable to move to either the bale of hay or the pail of water.

Metamorworks/iStock.

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Advancing Space For Humanity — Dr. Ezinne Uzo-Okoro, Ph.D. — Assistant Director for Space Policy, Office of Science and Technology Policy, The White House.

Dr. Ezinne Uzo-Okoro, Ph.D. is Assistant Director for Space Policy, Office of Science and Technology Policy, at the White House (https://www.whitehouse.gov/ostp/) where she focuses on determining civil and commercial space priorities for the President’s science advisor, and her portfolio includes a wide range of disciplines including Orbital Debris, On-orbit Servicing, Assembly, and Manufacturing (OSAM), Earth Observations, Space Weather, and Planetary Protection.

Previously, Dr. Uzo-Okoro built and managed over 60 spacecraft missions and programs in 17 years at NASA, in roles as an engineer, technical expert, manager and executive, in earth observations, planetary science, heliophysics, astrophysics, human exploration, and space communications, which represented $9.2B in total program value. Her last role was as a NASA Heliophysics program executive.

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Astrophysicists have performed a powerful new analysis that places the most precise limits yet on the composition and evolution of the universe. With this analysis, dubbed Pantheon+, cosmologists find themselves at a crossroads.

Pantheon+ convincingly finds that the cosmos is composed of about two-thirds dark energy and one-third matter—mostly in the form of dark matter—and is expanding at an accelerating pace over the last several billion years. However, Pantheon+ also cements a major disagreement over the pace of that expansion that has yet to be solved.

By putting prevailing modern cosmological theories, known as the Standard Model of Cosmology, on even firmer evidentiary and statistical footing, Pantheon+ further closes the door on alternative frameworks accounting for dark energy and dark matter. Both are bedrocks of the Standard Model of Cosmology but have yet to be directly detected and rank among the model’s biggest mysteries. Following through on the results of Pantheon+, researchers can now pursue more precise observational tests and hone explanations for the ostensible cosmos.

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Nuclear physicists have confirmed that the current description of proton structure isn’t all smooth sailing. A new precision measurement of the proton’s electric polarizability performed at the U.S. Department of Energy’s Thomas Jefferson National Accelerator Facility has revealed a bump in the data in probes of the proton’s structure.

Though widely thought to be a fluke when seen in earlier measurements, this new, more precise measurement has confirmed the presence of the anomaly and raises questions about its origin. The research has just been published in the journal Nature.

According to Ruonan Li, first author on the new paper and a graduate student at Temple University, measurements of the ’s electric polarizability reveal how susceptible the proton is to deformation, or stretching, in an electric field. Like size or charge, the electric polarizability is a fundamental property of proton structure.

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On Oct. 9, an unimaginably powerful influx of X-rays and gamma rays infiltrated our solar system. It was likely the result of a massive explosion that happened 2.4 billion light-years away from Earth, and it has left the science community stunned.

In the wake of the explosion, astrophysicists worldwide turned their telescopes toward the spectacular show, watching it unfold from a variety of cosmic vantage points — and as they vigilantly studied the event’s glimmering afterglow over the following week, they grew shocked by how utterly bright this gamma-ray burst seems to have been.

Eventually, the spectacle’s sheer intensity earned it a fitting (very millennial) name to accompany its robotic title of GRB221009A: B.O.A.T. — the “brightest of all time.”

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Imagine taking a star twice the mass of the sun and crushing it to the size of Manhattan. The result would be a neutron star—one of the densest objects found anywhere in the universe, exceeding the density of any material found naturally on Earth by a factor of tens of trillions. Neutron stars are extraordinary astrophysical objects in their own right, but their extreme densities might also allow them to function as laboratories for studying fundamental questions of nuclear physics, under conditions that could never be reproduced on Earth.

Because of these exotic conditions, scientists still do not understand what exactly themselves are made from, their so-called “equation of state” (EoS). Determining this is a major goal of modern astrophysics research. A new piece of the puzzle, constraining the range of possibilities, has been discovered by a pair of scholars at IAS: Carolyn Raithel, John N. Bahcall Fellow in the School of Natural Sciences; and Elias Most, Member in the School and John A. Wheeler Fellow at Princeton University. Their work was recently published in The Astrophysical Journal Letters.

Ideally, scientists would like to peek inside these exotic objects, but they are too small and distant to be imaged with standard telescopes. Scientists rely instead on indirect properties that they can measure—like the mass and radius of a neutron star—to calculate the EoS, the same way that one might use the length of two sides of a right-angled triangle to work out its hypotenuse. However, the radius of a neutron star is very difficult to measure precisely. One promising alternative for future observations is to instead use a quantity called the “peak spectral frequency” (or f2) in its place.

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In February 2016, scientists at the Laser Interferometer Gravitational-Wave Observatory (LIGO) announced the first-ever detection of gravitational waves (GWs). Originally predicted by Einstein’s Theory of General Relativity, these waves are ripples in spacetime that occur whenever massive objects (like black holes and neutron stars) merge. Since then, countless GW events have been detected by observatories across the globe – to the point where they have become an almost daily occurrence. This has allowed astronomers to gain insight into some of the most extreme objects in the Universe.

In a recent study, an international team of researchers led by Cardiff University observed a binary black hole system originally detected in 2020 by the Advanced LIGO, Virgo, and Kamioki Gravitational Wave Observatory (KAGRA). In the process, the team noticed a peculiar twisting motion (aka. a precession) in the orbits of the two colliding black holes that was 10 billion times faster than what was noted with other precessing objects. This is the first time a precession has been observed with binary black holes, which confirms yet another phenomenon predicted by General Relativity (GR).

The team was led by Professor Mark Hannam, Dr. Charlie Hoy, and Dr. Jonathan Thompson from the Gravity Exploration Institute at Cardiff University. They were joined by researchers from the LIGO Laboratory, the Barcelona Institute of Science and Technology, the Max Planck Institute for Gravitational Physics, the Institute for Gravitational Wave Astronomy, the ARC Centre of Excellence for Gravitational Wave Discovery, the Scottish Universities Physics Alliance (SUPA), and other GW research institutes.

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Data from the Parker Solar Probe confirms a long-suspected heat source for the Sun’s surprisingly hot corona, but there may be others.

The Sun’s surface temperature is around six thousand degrees kelvin, but the solar atmosphere—the corona and the solar wind—can reach a million degrees kelvin, a long-standing mystery in solar physics. Now, with data from the Parker Solar Probe, researchers have found evidence supporting a partial explanation for this mystery: magnetic waves driven by subsurface turbulence can impart energy to ions in these regions [1].

The exact mechanism of heating has been debated for decades, but the story appears to start with turbulent flow in the Sun’s convection zone, the outermost layer below the surface. In fluid dynamics, turbulence causes heating through a process known as turbulent energy cascade, where large eddies are converted into progressively smaller eddies. The energy in the smallest eddies is converted into heat through collisions between molecules.

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