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In Verlinde’s picture of emergent gravity, as soon as you enter low-density regions — basically, anything outside the solar system — gravity behaves differently than we would expect from Einstein’s theory of general relativity. At large scales, there is a natural inward pull to space itself, which forces matter to clump up more tightly than it otherwise would.

This idea was exciting because it allowed astronomers to find a way to test this new theory. Observers could take this new theory of gravity and put it in models of galaxy structure and evolution to find differences between it and models of dark matter.

Over the years, however, the experimental results have been mixed. Some early tests favored emergent gravity over dark matter when it came to the rotation rates of stars. But more recent observations haven’t found an advantage. And dark matter can also explain much more than galaxy rotation rates; tests within galaxy clusters have found emergent gravity coming up short.

Utilizing high-resolution three-dimensional radiation hydrodynamics simulations and a detailed supernova physics model run on supercomputers, a research team led by Dr. Ke-Jung Chen from the Institute of Astronomy and Astrophysics, Academia Sinica (ASIAA) has revealed that the physical properties of the first galaxies are critically determined by the masses of the first stars. Their study is published in The Astrophysical Journal.

Astronomers have created the largest yet cosmic 3D map of quasars: bright and active centres of galaxies powered by supermassive black holes. This map shows the location of about 1.3 million quasars in space and time, with the furthest shining bright when the Universe was only 1.5 billion years old.

The new map has been made with data from ESA’s Gaia space telescope. While Gaia’s main objective is to map the stars in our own galaxy, in the process of scanning the sky it also spots objects outside the Milky Way, such as quasars and other galaxies.

The graphic representation of the map (bottom right on the infographic) shows us the location of quasars from our vantage point, the centre of the sphere. The regions empty of quasars are where the disc of our galaxy blocks our view.

A superfluid vortex controlled in a lab is helping physicists learn more about the behavior of black holes.

A whirlpool generated in helium cooled to just a fraction above absolute zero mimics the gravitational environment of these objects to such high precision that it’s giving unprecedented insight into how they drag and warp the space-time around them.

“Using superfluid helium has allowed us to study tiny surface waves in greater detail and accuracy than with our previous experiments in water,” explains physicist Patrik Švančara of the University of Nottingham in the UK, who led the research.

Scientists have referred to black holes as cosmic objects that consume whatever comes into them but do not allow anything to escape from the inside. Stephen Hawking assumes that a black hole could be a portal to another universe. While addressing about 1,000 people at Harvard in 2015, Hawkings analyzed the groundbreaking theory with these words.

“Blackholes aren’t the eternal prisons they were once thought. Things can get out of a black hole, both from the outside and possibly through another universe. So, if you ever feel you’re in a black hole, don’t give up. There’s a way out.”

Scientists listening to the renowned astrophysicist were fascinated with his explanations. Keep in mind that Stephen Hawkings came up with Hawking’s radiation theory which revolutionized our understanding of black holes. According to this theory, Black holes thermally generate and emit subatomic particles until they lose their energy and proceed to evaporate. Based on this theory, Hawkings says that black holes are not entirely black and they don’t last for eternity.

Scientists have for the first time created a giant quantum vortex to mimic a black hole in superfluid helium that has allowed them to see in greater detail how analog black holes behave and interact with their surroundings.

Journey into the enigmatic depths of a black hole, with beloved physicist Carlo Rovelli. Buy Carlo’s book here: https://geni.us/nNB6xAsBecome one of our YouTu…

The new map includes around 1.3 million quasars from across the visible universe and could help scientists better understand the properties of dark matter.

Astronomers have charted the largest-ever volume of the universe with a new map of active supermassive black holes living at the centers of galaxies. Called quasars, the gas-gobbling black holes are, ironically, some of the universe’s brightest objects.

Continue reading “In a Major Astronomical Feat, 1.3 Million Quasars Illuminate the Universe’s Past” »

By stabilizing a stationary giant quantum vortex in superfluid 4He and introducing a minimally invasive way to characterize the vortex flow, intricate wave–vortex interactions are shown to simulate black hole ringdown physics.