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When the largest of stars dies, the supernova they produce can outshine a whole galaxy, and potentially sterilize vast swathes of space. Future civilizations will need to be able to prevent or mitigate such events, though some might seek to artificially ignite a nova.

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Continue reading “Killing Stars” »

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Interstellar travel is very time consuming, moving from star to star, but perhaps we could use stars themselves as spaceships, and move whole solar systems or even galaxies.
Today we’ll look at how to use Shkadov Thrusters, novas, supernovae, black holes and quasars to move through space, literal starships.

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Continue reading “Fleet of Stars” »

At this point, the paper mingles cosmology, or the study of the universe and its origins, with biology. “We ask whether there might be a mechanism woven into the fabric of the natural world, by means of which the universe could learn its laws,” the authors write. In other words, a universal law might transcend all scientific fields. That means that the laws of physics, as we know them, could be subject to higher-order laws of the universe that control them—and that we can’t even comprehend.

“Exploring links between fields is crucial because knowledge is not fundamentally compartmentalized,” says Bruce Bassett, professor at the University of Cape Town’s Department of Mathematics and head of the Cosmology Group at the African Institute of Mathematical Sciences in South Africa. We humans are simply narrow-minded. “We segment and compress knowledge into biology, and physics, and sociology because of our limited brains, and the cost of that segmentation and compression is that we easily miss the commonalities and hidden universality between branches of human knowledge.”

Physicist Max Tegmark on predictions that cannot be observed, explanation of Universe’ fine tuning, and quantum computer.

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A black hole laser in analogues of gravity amplifies Hawking radiation, which is unlikely to be measured in real black holes, and makes it observable. There have been proposals to realize such black hole lasers in various systems. However, no progress has been made in electric circuits for a long time, despite their many advantages such as high-precision electromagnetic wave detection. Here we propose a black hole laser in Josephson transmission lines incorporating metamaterial elements capable of producing Hawking-pair propagation modes and a Kerr nonlinearity due to the Josephson nonlinear inductance. A single dark soliton obeying the nonlinear Schrödinger equation produces a black hole-white hole horizon pair that acts as a laser cavity through a change in the refractive index due to the Kerr effect.

The European Southern Observatory’s Very Large Telescope Interferometer (ESO

Created in 1962, the European Southern Observatory (ESO), is a 16-nation intergovernmental research organization for ground-based astronomy. Its formal name is the European Organisation for Astronomical Research in the Southern Hemisphere.

Some of the world’s richest men are squaring off in what’s become a rivalry for the ages — the space race. Elon Musk and Jeff Bezos, the two richest men on the planet and the CEOs of SpaceX and Blue Origin, respectively, have grand designs on the cosmos. They predict a universe where the internet is accessible from anywhere, humans are an interplanetary species, and rotating space stations host permanent residents.

But Bill Gates isn’t putting his wealth into these off-planet endeavors.

Gates, the fourth richest person alive, according to Forbes, has what he considers higher aspirations right here on Earth. While internet constellations like SpaceX’s Starlink and Amazon’s proposed Project Kuiper aim to bring for-profit fixes to the world’s pressing connectivity issues, Gates told CNN’s Becky Anderson on Wednesday that more basic problems consume his time now.

In this work we propose a novel campaign for constraining relativistically compact MACHO dark matter, such as primordial black holes (PBHs), using the moon as a detector. PBHs of about $10^{19} \textrm{ g}$ to $10^{22} \textrm{ g}$ may be sufficiently abundant to have collided with the moon in the history of the solar system. We show that the crater profiles of a PBH collision differ from traditional impactors and may be detectable in high resolution lunar surface scans now available. Any candidates may serve as sites for in situ measurements to identify high pressure phases of matter which may have formed near the PBH during the encounter. While we primarily consider PBH dark matter, the discussion generalises to the entire family of MACHO candidates with relativistic compactness.

Abstract: We present new HI interferometric observations of the gas-rich ultra-diffuse galaxy AGC 114,905, which previous work, based on low-resolution data, identified as an outlier of the baryonic Tully-Fisher relation. The new observations, at a spatial resolution $\sim 2.5$ times higher than before, reveal a regular HI disc rotating at about 23 km/s. Our kinematic parameters, recovered with a robust 3D kinematic modelling fitting technique, show that the flat part of the rotation curve is reached. Intriguingly, the rotation curve can be explained almost entirely by the baryonic mass distribution alone. We show that a standard cold dark matter halo that follows the concentration-halo mass relation fails to reproduce the amplitude of the rotation curve by a large margin. Only a halo with an extremely (and arguably unfeasible) low concentration reaches agreement with the data. We also find that the rotation curve of AGC 114,905 deviates strongly from the predictions of Modified Newtonian dynamics. The inclination of the galaxy, which is measured independently from our modelling, remains the largest uncertainty in our analysis, but the associated errors are not large enough to reconcile the galaxy with the expectations of cold dark matter or Modified Newtonian dynamics.

From: Pavel Mancera-Piña [view email]

[v1] Tue, 30 Nov 2021 19:00:01 UTC (7,952 KB)