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Archive for the ‘cosmology’ category: Page 109

Aug 7, 2022

The dark matter hypothesis isn’t perfect, but the alternatives are worse

Posted by in categories: computing, cosmology, particle physics, satellites

But the dark matter hypothesis isn’t perfect. Computer simulations of the growth of galaxies suggest that dark-matter-dominated galaxies should have incredibly high densities in their centers. Observations of real galaxies do show higher densities in their cores, but not nearly enough as those simulations predicted. Also, simulations of dark matter evolving in the universe predict that every galaxy should have hundreds of smaller satellites, while observations consistently come up short.

Given that the dark matter hypothesis isn’t perfect — and that we have no direct evidence for the existence of any candidate particles — it’s worth exploring other options.

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Aug 5, 2022

Futureseek Daily Link Review; 05 August 2022

Posted by in categories: cosmology, cybercrime/malcode, economics, mathematics, particle physics, quantum physics, robotics/AI, space travel, surveillance

* At Long Last, Mathematical Proof That Black Holes Are Stable * Who Gets to Work in the Digital Economy? * Mice produce rat sperm with technique that could help conservation.

* Quantum computer can simulate infinitely many chaotic particles * Radar / AI & ML: Scaling False Peaks * Cyber security for the human world | George Loukas | TEDx.

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Aug 3, 2022

The universe’s oldest and farthest ‘dark matter’ finally revealed by scientists

Posted by in categories: cosmology, engineering

The faint light from galaxies far away prevented researchers from studying dark matter before. With this approach, they can peer further back in time.


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Aug 3, 2022

Two black holes merged despite being born far apart in space

Posted by in categories: cosmology, physics

A closer look at gravitational wave data reveals 10 overlooked mergers, including one between black holes that probably found each other late in life.

Aug 3, 2022

Time is the increase of order, not disorder

Posted by in categories: cosmology, mathematics, particle physics

The received view in physics is that the direction of time is provided by the second law of thermodynamics, according to which the passage of time is measured by ever-increasing disorder in the universe. This view, Julian Barbour argues, is wrong. If we reject Newton’s faulty assumptions about the existence of absolute space and time, Newtonian dynamics can be shown to provide a very different arrow of time. Its direction, according to this theory, is given by the increase in the complexity and order of a system of particles, exactly the opposite of what the received view about time suggests.

Two of the most established beliefs of contemporary cosmology are that the universe is expanding and that the direction of the arrow of time in the universe is defined by ever-increasing disorder (entropy), as described by the second law of thermodynamics. But both of these beliefs rest on shaky ground. In saying that the universe is expanding, physicists implicitly assume its size is measured by a rod that exists outside the universe, providing an absolute scale. It’s the last vestige of Newton’s absolute space and should have no place in modern cosmology. And in claiming that entropy is what gives time its arrow, physicists uncritically apply the laws of thermodynamics, originally discovered through the study of steam engines, to the universe as a whole. That too needs to be questioned.

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Aug 3, 2022

Scientists Just Detected the Oldest Dark Matter Ever Observed

Posted by in category: cosmology

Scientists at Nagoya University in Japan claim to have discovered dark matter that dates back 12 billion years ago, which would make it the earliest observation of the hypothetical substance to date.

Their findings — as detailed in a new paper published in the journal Physical Review Letters — could potentially offer some tantalizing answers about the nature of the universe.

Until now, observations of dark matter only went as far back as ten billion years. Any further than that, and the light was too faint to observe.

Aug 3, 2022

A Large Black Hole Collision Actually Shook Space-Time

Posted by in category: cosmology

Space is the coolest.

Aug 3, 2022

The Universe: Space Weapons Prepare for War (S4, E8) | Full Episode | History

Posted by in categories: cosmology, military, satellites

Outer space is already an essential part of America’s ability to fight wars. Our military depends on satellites for many things, such as communications, reconnaissance and targeting information. See more in Season 4, Episode 8, “Space Wars.”

#TheUniverse.

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Aug 3, 2022

Planets made of dark matter may have blown up, and we could see them

Posted by in category: cosmology

A new hypothesis proposes that a large fraction of dark matter may be bound up inside tight balls the size of Neptune — so-called dark matter planets.

Aug 3, 2022

A Star Just Turned Into A Black Hole Before Hubble’s Very Eyes

Posted by in category: cosmology

What remains are mostly neutron stars or black holes. And now, Hubble seems to have documented the instant when a supernova blinked out — implying that it captured the moment a black hole took control.

While some supernova explosions, such as SN 1,054, are violent and leave clouds of debris for thousands of years (a.k.a. nebula), the star in question seems to have exploded and then had all its gas pulled back into the black hole at the core. This may occur if the star’s core collapse is very big. Rather than exploding, the gas falls into the star’s core.