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Category: cosmology – Page 80

A team of scientists has successfully mimicked black hole conditions by creating a quantum vortex in superfluid helium, shedding light on gravitational interactions and quantum field theories in curved spacetimes.

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.

Research led by the University of Nottingham, in collaboration with King’s College London and Newcastle University, has created a novel experimental platform: a quantum tornado. They have created a giant swirling vortex within superfluid helium that is chilled to the lowest possible temperatures. Through the observation of minute wave dynamics on the superfluid’s surface, the research team has shown that these quantum tornados mimic gravitational conditions near rotating black holes. The research has been published today in Nature.

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When it comes to the cosmic conundrum of how early galaxies grew to become so massive so quickly Gz9p3 could be a real puzzle. Not only is it more massive than expected, but it is around 10 times more massive than other galaxies the JWST has seen in similar eras of the universe’s history.

Related: James Webb Space Telescope complicates expanding universe paradox by checking Hubble’s work

“Just a couple of years ago, Gz9p3 appeared as a single point of light through the Hubble Space Telescope,” Kit Boyett, team member and a scientist at the University of Melbourne, wrote for the institute’s Pursuit publication. “But by using the JWST we could observe this object as it was 510 million years after the Big Bang, around 13 billion years ago.”

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It is with sadness — and deep appreciation of my friend and colleague — that I must report the passing of Vernor Vinge.

The technological singularity —or simply the singularity[1] —is a hypothetical future point in time at which technological growth becomes uncontrollable and irreversible, resulting in unforeseeable consequences for human civilization.[2][3] According to the most popular version of the singularity hypothesis, I. J. Good’s intelligence explosion model, an upgradable intelligent agent will eventually enter a “runaway reaction” of self-improvement cycles, each new and more intelligent generation appearing more and more rapidly, causing an “explosion” in intelligence and resulting in a powerful superintelligence that qualitatively far surpasses all human intelligence.[4]

The first person to use the concept of a “singularity” in the technological context was the 20th-century Hungarian-American mathematician John von Neumann.[5] Stanislaw Ulam reports in 1958 an earlier discussion with von Neumann “centered on the accelerating progress of technology and changes in the mode of human life, which gives the appearance of approaching some essential singularity in the history of the race beyond which human affairs, as we know them, could not continue”.[6] Subsequent authors have echoed this viewpoint.[3][7]

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Everyone loves a two-for-one deal—even physicists looking to tackle unanswered questions about the cosmos. Now, scientists at the Department of Energy’s SLAC National Accelerator Laboratory are getting just such a twofer: Particle detectors originally developed to look for dark matter are now in a position to be included aboard the Line Emission Mapper (LEM), a space-based X-ray probe mission proposed for the 2030s.

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Think the Upside Down in Stranger Things is a work of fiction? Well, it is, but something eerily reminiscent of the Upside Down – dark matter, or a “dark mirror” universe – is being studied and taken very seriously by scientists.

So what exactly is dark matter? NASA explains, Like ordinary matter, dark matter takes up space and holds mass. But it doesn’t reflect, absorb, or radiate light – at least not enough for us to detect yet.

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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.

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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.

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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.

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