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DrEvil » 03 Jun 2013 14:49 wrote:What about gravity waves? If I understand it correctly, gravity is a static field, which means that its effects are felt immediately (It's not traveling through space, it is a distortion of space itself). Could "waves" be used to represent something akin to 0's and 1's?
No waiting around for photons to catch up. It's like if you measure the position of the Sun by light and gravity. It gives you two different positions.
barracuda » 04 Jun 2013 02:26 wrote:Wombaticus Rex » Mon Jun 03, 2013 6:03 am wrote:The directionality of the metaphor in the title is extremely telling, yes.
"Your brain grows like a tiny universe."
Much more satisfying, somehow.
justdrew » Tue Jun 04, 2013 2:33 am wrote:DrEvil » 03 Jun 2013 14:49 wrote:What about gravity waves? If I understand it correctly, gravity is a static field, which means that its effects are felt immediately (It's not traveling through space, it is a distortion of space itself). Could "waves" be used to represent something akin to 0's and 1's?
No waiting around for photons to catch up. It's like if you measure the position of the Sun by light and gravity. It gives you two different positions.
there's a reason for that, but it's not (apparently) due to gravity propagating instantly.
http://en.wikipedia.org/wiki/Speed_of_gravity
Wombaticus Rex » Mon Jun 03, 2013 9:40 pm wrote:Well, I think it's pretty remarkable that consciousness can achieve superlimnal backflips with a great deal of ease.
If we're looking for a realtime, whole-Universe communication system, the nuts and bolts might wind up looking pretty Jungian.
Wombaticus Rex » Tue Jun 04, 2013 5:22 am wrote:justdrew » Mon Jun 03, 2013 2:06 pm wrote:so the only thing they see connecting nodes is gravity, and a signal that is always ON isn't much of a signal.
That, is a very very non-trivial point, hot damn. Well said and thank you.
Ben D » 14 Jan 2015 21:54 wrote:Wombaticus Rex » Tue Jun 04, 2013 5:22 am wrote:justdrew » Mon Jun 03, 2013 2:06 pm wrote:so the only thing they see connecting nodes is gravity, and a signal that is always ON isn't much of a signal.
That, is a very very non-trivial point, hot damn. Well said and thank you.
^ Hmmmm....but the force of gravity is forever changing and it is interactive throughout the universe. The moon for example affects our oceans tides which in turn affect fish behaviour, etc.. This principle is at work everywhere in the universe as cosmic objects orbit other cosmic objects from the macro to the micro levels of the universe. I see gravitational force, which btw I suspect is zpe pressure at work, as the underlying unifying force of the universe.
Celestial boondocks: Study supports the idea that we live in a void
In a 2013 observational study, University of Wisconsin–Madison astronomer Amy Barger and her then-student Ryan Keenan showed that our galaxy, in the context of the large-scale structure of the universe, resides in an enormous void — a region of space containing far fewer galaxies, stars and planets than expected.
Now, a new study by a UW–Madison undergraduate, also a student of Barger’s, not only firms up the idea that we exist in one of the holes of the Swiss cheese structure of the cosmos, but helps ease the apparent disagreement or tension between different measurements of the Hubble Constant, the unit cosmologists use to describe the rate at which the universe is expanding today.
Results from the new study were presented here today (June 6, 2017) at a meeting of the American Astronomical Society.
The tension arises from the realization that different techniques astrophysicists employ to measure how fast the universe is expanding give different results. “No matter what technique you use, you should get the same value for the expansion rate of the universe today,” explains Ben Hoscheit, the Wisconsin student presenting his analysis of the apparently much larger than average void that our galaxy resides in. “Fortunately, living in a void helps resolve this tension.”
The reason for that is that a void — with far more matter outside the void exerting a slightly larger gravitational pull — will affect the Hubble Constant value one measures from a technique that uses relatively nearby supernovae, while it will have no effect on the value derived from a technique that uses the cosmic microwave background (CMB), the leftover light from the Big Bang.
The new study not only firms up the idea that we exist in one of the holes of the Swiss cheese structure of the cosmos, but sheds light on how we measure the rate at which the universe is expanding today.
The new Wisconsin report is part of the much bigger effort to better understand the large-scale structure of the universe. The structure of the cosmos is Swiss cheese-like in the sense that it is composed of “normal matter” in the form of voids and filaments. The filaments are made up of superclusters and clusters of galaxies, which in turn are composed of stars, gas, dust and planets. Dark matter and dark energy, which cannot yet be directly observed, are believed to comprise approximately 95 percent of the contents of the universe.
The void that contains the Milky Way, known as the KBC void for Keenan, Barger and the University of Hawaii’s Lennox Cowie, is at least seven times as large as the average, with a radius measuring roughly 1 billion light years. To date, it is the largest void known to science. Hoscheit’s new analysis, according to Barger, shows that Keenan’s first estimations of the KBC void, which is shaped like a sphere with a shell of increasing thickness made up of galaxies, stars and other matter, are not ruled out by other observational constraints.
“It is often really hard to find consistent solutions between many different observations,” says Barger, an observational cosmologist who also holds an affiliate graduate appointment at the University of Hawaii’s Department of Physics and Astronomy. “What Ben has shown is that the density profile that Keenan measured is consistent with cosmological observables. One always wants to find consistency, or else there is a problem somewhere that needs to be resolved.”
The bright light from a supernova explosion, where the distance to the galaxy that hosts the supernova is well established, is the “candle” of choice for astronomers measuring the accelerated expansion of the universe. Because those objects are relatively close to the Milky Way and because no matter where they explode in the observable universe, they do so with the same amount of energy, it provides a way to measure the Hubble Constant.
A map of the local universe as observed by the Sloan Digital Sky Survey. The orange areas have higher densities of galaxy clusters and filaments. Sloan Digital Sky Survey
Alternatively, the cosmic microwave background is a way to probe the very early universe. “Photons from the CMB encode a baby picture of the very early universe,” explains Hoscheit. “They show us that at that stage, the universe was surprisingly homogeneous. It was a hot, dense soup of photons, electrons and protons, showing only minute temperature differences across the sky. But, in fact, those tiny temperature differences are exactly what allow us to infer the Hubble Constant through this cosmic technique.”
A direct comparison can thus be made, Hoscheit says, between the ‘cosmic’ determination of the Hubble Constant and the ‘local’ determination derived from observations of light from relatively nearby supernovae.
The new analysis made by Hoscheit, says Barger, shows that there are no current observational obstacles to the conclusion that the Milky Way resides in a very large void. As a bonus, she adds, the presence of the void can also resolve some of the discrepancies between techniques used to clock how fast the universe is expanding.
Celestial boondocks: Study supports the idea that we live in a void
Half the universe’s missing matter has just been finally found
9 October 2017
By Leah Crane
Discoveries seem to back up many of our ideas about how the universe got its large-scale structure
Andrey Kravtsov (The University of Chicago) and Anatoly Klypin (New Mexico State University). Visualisation by Andrey Kravtsov
The missing links between galaxies have finally been found. This is the first detection of the roughly half of the normal matter in our universe – protons, neutrons and electrons – unaccounted for by previous observations of stars, galaxies and other bright objects in space.
You have probably heard about the hunt for dark matter, a mysterious substance thought to permeate the universe, the effects of which we can see through its gravitational pull. But our models of the universe also say there should be about twice as much ordinary matter out there, compared with what we have observed so far.
Two separate teams found the missing matter – made of particles called baryons rather than dark matter – linking galaxies together through filaments of hot, diffuse gas.
“The missing baryon problem is solved,” says Hideki Tanimura at the Institute of Space Astrophysics in Orsay, France, leader of one of the groups. The other team was led by Anna de Graaff at the University of Edinburgh, UK.
Because the gas is so tenuous and not quite hot enough for X-ray telescopes to pick up, nobody had been able to see it before.
“There’s no sweet spot – no sweet instrument that we’ve invented yet that can directly observe this gas,” says Richard Ellis at University College London. “It’s been purely speculation until now.”
So the two groups had to find another way to definitively show that these threads of gas are really there.
Both teams took advantage of a phenomenon called the Sunyaev-Zel’dovich effect that occurs when light left over from the big bang passes through hot gas. As the light travels, some of it scatters off the electrons in the gas, leaving a dim patch in the cosmic microwave background – our snapshot of the remnants from the birth of the cosmos.
Stack ‘em up
In 2015, the Planck satellite created a map of this effect throughout the observable universe. Because the tendrils of gas between galaxies are so diffuse, the dim blotches they cause are far too slight to be seen directly on Planck’s map.
Both teams selected pairs of galaxies from the Sloan Digital Sky Survey that were expected to be connected by a strand of baryons. They stacked the Planck signals for the areas between the galaxies, making the individually faint strands detectable en masse.
Tanimura’s team stacked data on 260,000 pairs of galaxies, and de Graaff’s group used over a million pairs. Both teams found definitive evidence of gas filaments between the galaxies. Tanimura’s group found they were almost three times denser than the mean for normal matter in the universe, and de Graaf’s group found they were six times denser – confirmation that the gas in these areas is dense enough to form filaments.
“We expect some differences because we are looking at filaments at different distances,” says Tanimura. “If this factor is included, our findings are very consistent with the other group.”
Finally finding the extra baryons that have been predicted by decades of simulations validates some of our assumptions about the universe.
“Everybody sort of knows that it has to be there, but this is the first time that somebody – two different groups, no less – has come up with a definitive detection,” says Ralph Kraft at the Harvard-Smithsonian Center for Astrophysics in Massachusetts.
“This goes a long way toward showing that many of our ideas of how galaxies form and how structures form over the history of the universe are pretty much correct,” he says.
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