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Archive for the ‘cosmology’ category: Page 324

Nov 19, 2015

Dark matter dominates in nearby dwarf galaxy

Posted by in categories: cosmology, particle physics

Dark matter is called “dark” for a good reason. Although they outnumber particles of regular matter by more than a factor of 10, particles of dark matter are elusive. Their existence is inferred by their gravitational influence in galaxies, but no one has ever directly observed signals from dark matter. Now, by measuring the mass of a nearby dwarf galaxy called Triangulum II, Assistant Professor of Astronomy Evan Kirby may have found the highest concentration of dark matter in any known galaxy.

Triangulum II is a small, faint galaxy at the edge of the Milky Way, made up of only about 1,000 stars. Kirby measured the mass of Triangulum II by examining the velocity of six stars whipping around the galaxy’s center. “The galaxy is challenging to look at,” he says. “Only six of its stars were luminous enough to see with the Keck telescope.” By measuring these stars’ velocity, Kirby could infer the gravitational force exerted on the stars and thereby determine the mass of the galaxy.

“The total mass I measured was much, much greater than the mass of the total number of stars—implying that there’s a ton of densely packed dark matter contributing to the total mass,” Kirby says. “The ratio of dark matter to luminous matter is the highest of any galaxy we know. After I had made my measurements, I was just thinking—wow.”

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Nov 13, 2015

Mysteriously quiet space baffles researchers

Posted by in categories: cosmology, physics

Astrophysicists have concluded the yet most precise search for the gravitational wave background created by supermassive black hole mergers. But the expected signal isn’t there.

Last month, Lawrence Krauss rumored that the newly updated gravitational wave detector LIGO had seen its first signal. The news spread quickly – and was shot down almost as quickly. The new detector still had to be calibrated, a member of the collaboration explained, and a week later it emerged that the signal was probably a test run.

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Nov 7, 2015

The light side of dark matter

Posted by in category: cosmology

New technology and new thinking are pushing the dark matter hunt to lower and lower masses.

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Nov 4, 2015

Hawking — Proposing a solution for the Black Hole Information Paradox

Posted by in categories: cosmology, physics

In an article published on her blog Sabine Hossenfelder suggests, not altogether tongue in cheek, that the results of a recent experiment by Jeff Steinhauer about Hawking radiation (full title of the paper “Observation of Thermal Hawking Radiation and its entanglement in an analogue black hole”) might earn a ‘return visit’ to Stockholm for Hawking in order to collect a Nobel Prize. I don’t think that Steinhauer’s work, impressive as it might seem, and as well presented as it is, will lead to any return visit to Stockholm for Stephen Hawking (or at least not anytime soon…), but I do think that a much more significant development is gathering pace that will have a far reaching effect on our understanding of the universe and provide a resolution to a long standing problem in theoretical physics thats just as important if not more important than winning a Nobel Prize.

I refer to Hawking’s brief comments made on August 25th at the Swedish Royal Institute for Technology at a conference on Hawking Radiation sponsored by the Nordic Institute for Theoretical Physic s (NORDITA). Hawking’s comments were made during the course of a short (8 minute) presentation that could well end up being the most significant scientific advance made in the century since Einstein’s paper on General Relativity was published in November 1915. That’s no small claim, but one that is increasingly looking as if it has some serious merit.

This short note describes in a little more detail why I believe this to be the case.

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Nov 2, 2015

Dumb Holes Leak

Posted by in categories: cosmology, particle physics, quantum physics

In August I went to Stephen Hawking’s public lecture in the fully packed Stockholm Opera. Hawking was wheeled onto the stage, placed in the spotlight, and delivered an entertaining presentation about black holes. The silence of the audience was interrupted only by laughter to Hawking’s well-placed jokes. It was a flawless performance with standing ovations.

In his lecture, Hawking expressed hope that he will win the Nobelprize for the discovery that black holes emit radiation. Now called “Hawking radiation,” this effect should have been detected at the LHC had black holes been produced there. But time has come, I think, for Hawking to update his slides. The ship to the promised land of micro black holes has long left the harbor, and it sunk – the LHC hasn’t seen black holes, has not, in fact, seen anything besides the Higgs.

But you don’t need black holes to see Hawking radiation. The radiation is a consequence of applying quantum field theory in a space- and time-dependent background, and you can use some other background to see the same effect. This can be done, for example, by measuring the propagation of quantum excitations in Bose-Einstein condensates. These condensates are clouds of about a billion or so ultra-cold atoms that form a fluid with basically zero viscosity. It’s as clean a system as it gets to see this effect. Handling and measuring the condensate is a big experimental challenge, but what wouldn’t you do to create a black hole in the lab?

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Nov 1, 2015

Researcher shows that black holes do not exist

Posted by in categories: cosmology, physics

Black holes have long captured the public imagination and been the subject of popular culture, from Star Trek to Hollywood. They are the ultimate unknown – the blackest and most dense objects in the universe that do not even let light escape. And as if they weren’t bizarre enough to begin with, now add this to the mix: they don’t exist.

By merging two seemingly conflicting theories, Laura Mersini-Houghton, a physics professor at UNC-Chapel Hill in the College of Arts and Sciences, has proven, mathematically, that can never come into being in the first place. The work not only forces scientists to reimagine the fabric of space-time, but also rethink the origins of the universe.

“I’m still not over the shock,” said Mersini-Houghton. “We’ve been studying this problem for a more than 50 years and this solution gives us a lot to think about.”

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Oct 30, 2015

Scientist Claims He Has Found Evidence Of Other Universes

Posted by in category: cosmology

A new study submitted to the Astrophysical Journal has claimed to have found evidence of interactions between our universe and other universes by looking at the cosmic microwave background (CMB). The scientist discovered an anomaly associated with some regions of the CMB, and he believes it is evidence for alternate universes.

Dr Ranga Chary, the author of the study, wrote that his observations could “possibly be due to the collision of our universe with an alternate universe whose baryon to photon ratio is a factor of about 65 larger than ours.” A pre-print of the study, which is yet to be peer reviewed, is available on ArXiv.

The CMB is the first light that shone in the universe. It was emitted 370,000 years after the Big Bang when the universe was cool enough for hydrogen to form and the original photons were free to move without getting absorbed by the primordial matter.

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Oct 29, 2015

Warp Factor 11 — ships powered by BLACK HOLES to “outpace Enterprise”, say scientists

Posted by in categories: cosmology, energy, food, space travel

The novel its a bit older, but it‘s an incredible vision!


When Star Trek’s Scotty warns the Captain that the engines can’t “take it”, he might just be best off switching fuel — a new book claims that humanity could reach the stars using vast spacecraft harnessing the energy of black holes with the power to “eat planets”.

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Oct 22, 2015

Time Travel & The Multiverse – Many Worlds: Many Timelines

Posted by in categories: cosmology, time travel

Excerpt from This Book Is From the Future: A Journey Through Portals, Relativity, Wormholes and Other Adventures in Time Travel by Marie D. Jones & Larry Flaxman.

Time travel has enchanted and intrigued us since the earliest days of fiction, when authors such as H.G. Wells, Samuel Madden, Charles Dickens and Enrique Gaspar y Rimbau stretched and challenged our imaginations with images and tales of men and women who invented amazing machines and devices that could take them back in time, or forward into the future.

Because of the restrictions of light speed, and the paradoxes of going back to the past without damaging the future timeline, and a host of other obstacles and challenges, we, in fact, have remained stuck in the present.

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Oct 22, 2015

This Is What it Looks Like When a Black Hole Shreds a Star

Posted by in categories: cosmology, evolution

When a star wanders too close to a black hole, immense gravitational forces begin to rip it apart in an epic cosmic slaying called a “tidal disruption event.” Some of the star’s mass is flung outward into space, while the rest is drawn in, triggering a powerful flare that showers the sky with x-rays.

Using NASA’s Chandra X-ray Observatory and other telescopes, a team of astronomers has now pieced together one such astronomical feasting frenzy. The event in question, appropriately named “ASASSN-14li,” was spotted near the center of PGC 043234, a galaxy that lies 290 million light years from Earth.

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