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 Post subject: Re: Cosmology Thread
PostPosted: Wed Mar 08, 2017 10:27 am 
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Our Universe’s Very Dusty Early, Early Beginnings

https://www.nytimes.com/2017/03/08/scie ... verse.html

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The light from A2744_YD4, as it is known, has been on its way to us for 13.2 billion years, since the universe was only 600 million years old.


This Is The Coldest Place In The Universe

http://www.seeker.com/this-is-the-colde ... 77507.html

Quote:
At a positively frigid one Kelvin (that equates to –458 degrees Fahrenheit or –272 degrees Celsius), the Boomerang Nebula in the constellation Centaurus is officially the coldest known place in the entire Universe. It’s even colder than the background temperature of space!

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 Post subject: Re: Cosmology Thread
PostPosted: Thu Mar 09, 2017 8:25 am 
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This Bizarre Pocket of the Universe Suggests We're Wrong About How Stars Form

http://www.sciencealert.com/this-bizarr ... stars-form

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 Post subject: Re: Cosmology Thread
PostPosted: Thu Mar 23, 2017 7:31 am 
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'Mini Big Bang' Observed in Space could Disprove Einstein

http://mysteriousuniverse.org/2017/03/m ... -einstein/

Quote:
The researchers speculate that at some point between 7 and 11 billion years ago, our Milky Way galaxy and the nearby Andromeda galaxy passed closely by one another, creating a “mini Big Bang.” This event could have caused wave-like gravity ripples in space that could have sent smaller galaxies flinging out into space.


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Running Away from Einstein

https://www.st-andrews.ac.uk/news/archi ... 412,en.php

Quote:
If true, the discovery would force a new understanding of gravity and about our cosmos, as such a galactic flyby only makes sense if gravity weakens more slowly as galaxies drift apart than mainstream thinking suggests.

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 Post subject: Re: Cosmology Thread
PostPosted: Mon Mar 27, 2017 8:15 am 
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Astronomers Build a Family Tree for the Milky Way's Stars

https://www.scientificamerican.com/arti ... ays-stars/

Quote:
DNA can reveal how organisms are related, and the chemical makeup of a star can similarly be used to determine its ancestry. Stars are thermonuclear forges, fusing light elements such as hydrogen and helium into heavier ones such as carbon and oxygen. When stars die, they eject this material into space, where it can in turn form new suns. Each subsequent generation of stars will thus become more enriched with heavy elements—and thus their chemical composition offers information about their stellar genealogy. By surveying the chemistry of several stars in our galactic neighborhood, a team of astronomers has now grouped them into a distinct family tree, and uncovered clues about their origins.

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 Post subject: Re: Cosmology Thread
PostPosted: Fri Mar 31, 2017 9:41 pm 
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New Simulations Suggest Dark Energy Might Not Exist

http://www.sciencealert.com/bubbles-of- ... ark-energy

Quote:
Earlier this year, a study published in Science suggested dark energy could be explained as a kind of deficit, as if the Universe was 'leaking energy' at some point in its evolution.

While it breaks one of the big rules of physics (energy can't be lost or created) it would also take care of the nagging question mark over what 68 percent of the Universe is made out of.

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 Post subject: Re: Cosmology Thread
PostPosted: Tue May 16, 2017 3:13 pm 
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Using Einstein’s ‘spooky action at a distance’ to hear ripples in spacetime

https://cosmosmagazine.com/physics/usin ... -spacetime

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Quantum entanglement could help improve gravitational wave detectors beyond the quantum limit. Cathal O’Connell explains.

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 Post subject: Re: Cosmology Thread
PostPosted: Mon May 22, 2017 4:05 pm 
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Rare Supernovae May Solve 40-Year-Old Antimatter Mystery

https://www.scientificamerican.com/arti ... r-mystery/

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The new work suggests that those supernovas could be sufficient to create all of the unexplained positrons, thus solving the galaxy-wide mystery.

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 Post subject: Re: Cosmology Thread
PostPosted: Mon May 29, 2017 2:31 pm 
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‘Extraordinarily Bright’ Mystery Object Spotted in Galaxy Cygnus A

http://mysteriousuniverse.org/2017/05/e ... -cygnus-a/

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 Post subject: Re: Cosmology Thread
PostPosted: Tue May 30, 2017 4:04 pm 
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Do Stars Fall Quietly into Black Holes, or Crash into Something Utterly Unknown?

http://www.astrowatch.net/2017/05/do-st ... holes.html

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 Post subject: Re: Cosmology Thread
PostPosted: Tue May 30, 2017 11:01 pm 
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Ravenous Supermassive Black Holes May Sterilize Nearby Planets

https://www.scientificamerican.com/arti ... y-planets/

Quote:
Although quasars are known to drive strong winds and jets of relativistic particles that can be dangerous in their own right, Forbes and Loeb looked at the damage caused by their light alone. The accretion disk of debris that orbits the black holes, funneling gas and dust in, are so bright they can outshine all the stars in their galaxies, which are 100,000 times larger. And when that light illuminates the atmosphere of a planet, the high-energy photons transfer energy to those atmospheric particles, giving them the boost to escape the planet’s gravitational pull altogether. Outside experts like Duncan Forgan from the University of Saint Andrews in Scotland are quick to point out the amount of loss depends greatly on the atmosphere’s composition and the planet’s mass. This finding is one piece in a several-million-piece, three-dimensional puzzle, he says, but nonetheless it is still that crucial first piece.

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 Post subject: Re: Cosmology Thread
PostPosted: Thu Jun 08, 2017 6:14 am 
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'Cosmic void' theory suggests our Universe is like Swiss cheese and we live in one of its holes

https://www.wired.co.uk/article/galaxy-massive-void

Quote:
Now, physicists at the University of Wisconsin-Madison have added weight to this theory after showing the cosmic void idea can be used to solve another problem astronomers have observed; the expansion rate of the Universe.


Astronomers Just Did What Einstein Said Was Impossible: Weigh a Star With Gravity

https://www.sciencealert.com/astronomer ... first-time

Einstein rings, fam.

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 Post subject: Re: Cosmology Thread
PostPosted: Fri Jun 09, 2017 8:43 am 
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3 Separate Experiments Report Signs of a Phenomenon Beyond The Standard Model of Physics

https://www.sciencealert.com/3-separate ... of-physics

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"A confirmation of these results would point to new particles or interactions, and could have profound implications for our understanding of particle physics."

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 Post subject: Re: Cosmology Thread
PostPosted: Sun Jun 11, 2017 12:05 pm 
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The Largest Virtual Universe Ever Simulated

http://www.astrowatch.net/2017/06/the-l ... -ever.html

Quote:
Over a period of three years, a group of astrophysicists from the University of Zurich has developed and optimised a revolutionary code to describe with unprecedented accuracy the dynamics of dark matter and the formation of large-scale structures in the Universe. As Joachim Stadel, Douglas Potter and Romain Teyssier report in their recently published paper, the code (called PKDGRAV3) has been designed to use optimally the available memory and processing power of modern supercomputing architectures, such as the "Piz Daint" supercomputer of the Swiss National Computing Center (CSCS). The code was executed on this world-leading machine for only 80 hours, and generated a virtual universe of two trillion (i.e., two thousand billion or 2 x 1012) macro-particles representing the dark matter fluid, from which a catalogue of 25 billion virtual galaxies was extracted.

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 Post subject: Re: Cosmology Thread
PostPosted: Wed Jun 14, 2017 7:14 am 
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The idea of creating a new universe in the lab is no joke

https://aeon.co/ideas/the-idea-of-creat ... is-no-joke

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 Post subject: Re: Cosmology Thread
PostPosted: Fri Jun 23, 2017 4:24 pm 
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Massive, ‘Dead’ Galaxy Puzzles Astronomers

http://blogs.discovermagazine.com/d-bri ... xy-hubble/

Quote:
So as a disk galaxy in the early universe that’s evolved past its star-forming phase into the dead phase without mergers, MACS 2129-1 challenges that picture.

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 Post subject: Re: Cosmology Thread
PostPosted: Mon Jun 26, 2017 2:01 pm 
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Two Conjectures Collide, Endangering The Naked Singularity

https://www.wired.com/story/two-conject ... ingularity

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 Post subject: Re: Cosmology Thread
PostPosted: Mon Jun 26, 2017 2:22 pm 
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Chaos Makes the Multiverse Unnecessary

http://nautil.us/issue/49/the-absurd/ch ... nnecessary

Quote:
There is another, more interesting, explanation for the structure of the laws of nature. Rather than saying that the universe is very structured, say that the universe is mostly chaotic and for the most part lacks structure. The reason why we see the structure we do is that scientists act like a sieve and focus only on those phenomena that have structure and are predictable. They do not take into account all phenomena; rather, they select those phenomena they can deal with.

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 Post subject: Re: Cosmology Thread
PostPosted: Sat Jul 01, 2017 1:05 pm 
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Scientists Assert That Hidden Dimensions Might Exist in Gravitational Waves

https://futurism.com/scientists-assert- ... nal-waves/

Quote:
The study explores the consequences extra dimensions could have on gravitational waves, and offers predictions about whether or not we might be able to detect their effects. “Physicists have been looking for extra dimensions at the Large Hadron Collider at CERN but up to now this search has yielded no results,” second author of the study Dr. Gustavo Lucena Gómez said in a press release. “But gravitational wave detectors might be able to provide experimental evidence.”

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 Post subject: Re: Cosmology Thread
PostPosted: Thu Sep 07, 2017 9:20 am 
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What is the shape of space?

https://aeon.co/videos/why-the-apparent ... al-mystery

Video link.

Rather, the universe is a dodecahedron.

http://physicsworld.com/cws/article/new ... decahedron

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 Post subject: Re: Cosmology Thread
PostPosted: Wed Sep 20, 2017 4:22 pm 
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Do We Live in a ‘Normal’ Galaxy?

http://blogs.discovermagazine.com/d-bri ... /20/21099/

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 Post subject: Re: Cosmology Thread
PostPosted: Thu Sep 21, 2017 8:52 am 
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Research Claims the Universe is most likely NOT Expanding

http://www.physics-astronomy.com/2017/0 ... nding.html

Quote:
David Wiltshire of the University of Canterbury in Christchurch New Zealand, the leader of the study said the following, potentially revolutionary words: “The past debate missed an essential point; if dark energy does not exist then a likely alternative is that the average expansion law does not follow Friedmann's equation."


Source article:

https://www.ras.org.uk/news-and-press/3 ... rgy-debate

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 Post subject: Re: Cosmology Thread
PostPosted: Thu Sep 21, 2017 8:19 pm 
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Gravity may be created by strange flashes in the quantum realm

https://www.newscientist.com/article/mg ... d-gravity/

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 Post subject: Re: Cosmology Thread
PostPosted: Fri Sep 22, 2017 10:14 pm 
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What Happens When Two Neutron Stars Collide? Scientific Revolution

https://www.wired.com/story/what-happen ... revolution

Quote:
While two merging black holes are thought to produce nothing detectable beyond a crescendo of gravitational waves, events involving two neutron stars or a neutron star and a black hole could also leave behind a glowing wreckage for telescopes to see. LIGO has yet to confirm that such an event has been detected. “Some promising gravitational-wave candidates have been identified in data from both LIGO and Virgo during our preliminary analysis, and we have shared what we currently know with astronomical observing partners,”

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 Post subject: Re: Cosmology Thread
PostPosted: Thu Sep 28, 2017 4:07 pm 
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Is The Inflationary Universe A Scientific Theory? Not Anymore

https://www.forbes.com/sites/startswith ... t-anymore/

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 Post subject: Re: Cosmology Thread
PostPosted: Tue Oct 03, 2017 12:55 pm 
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Is Space-Time Fluid?

https://iainews.iai.tv/articles/is-spac ... d-auid-897

Quote:
Physicists have gathered evidence that space-time can behave like a fluid. Mathematical evidence, that is, but still evidence. If this relation isn’t a coincidence, then space-time – like a fluid – may have a substructure.

We shouldn’t speak of space and time as if the two were distant cousins. We have known at least since Einstein that space and time are inseparable, two hemispheres of the same cosmic brain, joined to a single entity: space-time. Einstein also taught us that space-time isn’t flat, like paper, but bent and wiggly, like a rubber sheet. Space-time curves around mass and energy and this gives rise to the effect we call gravity.

That’s what Einstein said. But turns out if you write down the equations for small wiggles in a medium – such as soundwaves in a fluid – then the equations look exactly like those of waves in a curved background.<br><br> Yes, that’s right. Sometimes, waves in fluids behave like waves in a curved space-time; they behave like waves in a gravitational field. Fluids, therefore, can be used to simulate gravity. And that’s some awesome news because this correspondence between fluids and gravity allows physicists to study situations that are otherwise experimentally inaccessible; for example, what happens near a black hole horizon or during the rapid expansion of the early universe.

This mathematical relation between fluids and gravity is known as “analog gravity.” That’s “analog” as in “analogy” not as opposed to digital. But it’s not just math. The first gravitational analogies have been created in a laboratory.

Most amazing is the work by Jeff Steinhauer at Technion, Haifa. Steinhauer used a condensate of supercooled atoms that “flows” in a potential of laser beams which simulate the black hole horizon. In his experiment, Steinhauer wanted to test whether black holes emit radiation as Stephen Hawking predicted. The temperature of real, astrophysical, black holes is too small to be measurable. But if Hawking’s calculation is right, then the fluid-analogy of black holes should radiate too.

Black holes trap light behind the “event horizon.” A fluid that simulates a black hole doesn’t trap light; instead it traps the fluid’s soundwaves behind what is called the “acoustic horizon.” Since the fluid analogies of black holes aren’t actually black, Bill Unruh suggested calling them “dumb holes.” The name stuck.

What if the fluid analogy is more than an analogy? Maybe space-time really behaves like a fluid; maybe it is a fluid.

But whether the horizon catches light or sound, Hawking-radiation should be produced regardless, and it should appear in form of fluctuations (in the fluid or quantum matter fields, respectively) that are paired across the horizon.

Steinhauer claims he has measured Hawking-radiation produced by an acoustic black hole. His results are, at present, somewhat controversial – not everyone is convinced he has really measured what he claims he did – but I am that sure sooner or later this will be settled. More interesting is that Steinhauer’s experiment showcases the potential of the method.

Of course fluid-analogies are still different from real gravity. Mathematically, the most important difference is that the curved space-time which the fluid mimics has to be designed. It is not, unlike real gravity, an automatic reaction to energy and matter; instead, it is part of the experimental setup. However, this is a problem which, at least in principle, can be overcome with a suitable feedback loop.

The conceptually more revealing difference is that the fluid’s correspondence to a curved space-time breaks down once the experiment starts to resolve the fluid’s atomic structure. Fluids, we know, are made of smaller things. Curved space-time, for all we know at present, isn’t. But how certain are we of this? What if the fluid analogy is more than an analogy? Maybe space-time really behaves like a fluid; maybe it a fluid. And if so, the experiments with fluid-analogies may reveal how we can find evidence for a substructure of space-time.

Some have pushed the gravity-fluid analogy even further. Gia Dvali from LMU Munich, for example, has proposed that real black holes are condensates of gravitons, the hypothetical quanta of the gravitational field. This simple idea, he claims, explains several features of black holes which have so-far puzzled physicists, notably the question how black holes manage to keep the information that falls into them.

We used to think black holes were almost featureless round spheres. But if they are instead, as Dvali says, condensates of many gravitons, then black holes can take on many slightly different configurations in which information can be stored. Even more interesting, Dvali proposes the analogy could be used to design fluids which are as efficient at storing and distributing information as black holes are. The link between condensed matter and astrophysics, hence, works both ways.

Physicists have looked for evidence of space-time being a medium for some while. For example, by studying light from distant sources, such as gamma-ray bursts, they tried to find out whether space has viscosity or whether it causes dispersion (a running apart of frequencies like in a prism). A new line of research is to search for impurities – “space-time defects” – like crystals have. So far the results have been negative. But the experiments with fluid analogies might point the way forward.

If space-time is made of smaller things, this could solve a major problem: how to describe the quantum behavior of space time. Unlike all the other interactions we know of, gravity is a non-quantum theory. This means it doesn’t fit together with the quantum theories that physicists use for elementary particles. All attempts to quantize gravity so-far have either failed or remained unconfirmed speculations. That space itself isn’t fundamental but made of other things is one way to approach the problem.

Not everyone likes the idea. What irks physicists most about giving substance to space-time is that this breaks Einstein’s bond between space and time which has worked dramatically well – so far. Only further experiment will reveal whether Einstein’s theory holds up.
Time flows, they say. Maybe space does too."

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