Lecture from the mini-series “Cosmology & Quantum Foundations” from the “Philosophy of Cosmology” project. A University of Oxford and Cambridge Collaboration.
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Today I tell you how my opinion about dark matter has changed an why. Is modified gravity better or worse? What evidence speaks for one side or the other, and is the case really as clear-cut as many astrophysicists claim?
A team of researchers at the Sorbonne University of Paris reports a new way to emulate black hole and stellar accretion disks. In their paper published in the journal Physical Review Letters, the group describes using magnetic and electric fields to create a rotating disk made of liquid metal to emulate the behavior of material surrounding black holes and stars, which leads to the development of accretion disks.
Prior research has shown that massive objects have a gravitational reach that pulls in gas, dust and other material. And since such massive objects tend to spin, the material they pull in tends to swirl around the object as it moves closer. When that happens, gravity exerted by materials in the swirling mass tends to coalesce, resulting in an accretion disk. Astrophysicists have been studying the dynamics of accretion disks for many years but have not been able to figure out how angular momentum is transferred from the inner parts of a given accretion disk to its outer parts as material in the disk moves ever closer to the central object.
Methods used to study accretion disks have involved the development of math formulas, computer simulations and real-world models using liquids that swirl like eddies. None of the approaches has proven suitable, however, which has led researchers to look for new models. In this new effort, the researchers developed a method to generate an accretion disk made of liquid metal bits spinning in the air.
Why was NASA’s Artemis launch date rescheduled for 3 Sep 22? Get the real skinny here.
Why was NASA’s Artemis Iaunch date rescheduled for 3 Sep 22? Get the real skinny here.
Continue reading “Artemis I New Launch Date and Starship Launch” »
The weird behavior of a galaxy around a billion light-years away suggests that it might contain one of the most highly anticipated events in modern astronomy…
Luke barnes, lecturer in physics, western sydney university miroslav filipovic, professor, western sydney university ray norris, professor, school of science, western sydney university velibor velović, phd candidate, western sydney university.
Astronomers at Western Sydney University have discovered one of the biggest black hole jets in the sky.
Spanning more than a million light years from end to end, the jet shoots away from a black hole with enormous energy, and at almost the speed of light. But in the vast expanses of space between galaxies, it doesn’t always get its own way.
When astronomers use radio telescopes to gaze into the night sky, they typically see elliptical-shaped galaxies, with twin jets blasting from either side of their central supermassive black hole. But every once in a while—less than 10% of the time—astronomers might spot something special and rare: An X-shaped radio galaxy, with four jets extending far into space.
Although these mysterious X-shaped radio galaxies have confounded astrophysicists for two decades, a new Northwestern University study sheds new insight into how they form—and its surprisingly simple. The study also found that X-shaped radio galaxies might be more common than previously thought.
Continue reading “X-shaped radio galaxies might form more simply than expected” »
What is the real reason the NASA Artemis I Launch got scrubbed on 29 Aug 21? NASA made a valiant attempt to launch the SLS Artemis I Moon Rocket this morning, but it was not to be. The launch was scrubbed. Get the real skinny here.
Worm-hole generators by the pound mass: https://greengregs.com/
Continue reading “The Real Reason the Artemis I Launch Was Scrubbed” »
As her new book on the origins of the universe is published, the Albanian-American scientist explains how her work on multiverse theory influenced Stephen Hawking.
Then a mere scientist pulled it off. Otto von Guericke invented a pump to suck the air from within a hollow copper sphere, establishing perhaps the first high-quality vacuum on Earth. In a theatrical demonstration in 1,654, he showed that not even two teams of horses straining to rip apart the watermelon-size ball could overcome the suction of nothing.
Since then, the vacuum has become a bedrock concept in physics, the foundation of any theory of something. Von Guericke’s vacuum was an absence of air. The electromagnetic vacuum is the absence of a medium that can slow down light. And a gravitational vacuum lacks any matter or energy capable of bending space. In each case the specific variety of nothing depends on what sort of something physicists intend to describe. “Sometimes, it’s the way we define a theory,” said Patrick Draper, a theoretical physicist at the University of Illinois.
As modern physicists have grappled with more sophisticated candidates for the ultimate theory of nature, they have encountered a growing multitude of types of nothing. Each has its own behavior, as if it’s a different phase of a substance. Increasingly, it seems that the key to understanding the origin and fate of the universe may be a careful accounting of these proliferating varieties of absence.
