#100: 0) Universe Nature/Models: 0. Electricity. 1. "Quantum". 2. "Fractal". 3. "Swiss Cheese". 1) Earth. 08.6.25=3 - 09.3.4=3 11pm.

#100: 0) Universe Nature & Models: Electricity, "Quantum", "Fractal" & "Swiss Cheese" Models. 1) Earth. 08.6.25 - 00.3.4=3 11pm:

'Naming Astronomical Objects' http://tinyurl.com/4sf8xz < IAU
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0-) Universe Nature:--------------

0-0-) 'Scientists explore what happened before the universe's theoretical beginning' http://tinyurl.com/4vv645

0-0-0-) 0. 'Mysterious New 'Dark Flow' Discovered in Space' http://tinyurl.com/3ln6tn
0-0-0-) 1. 'Giant simulation could solve mystery of dark matter' http://tinyurl.com/5e95x2

0-0-0-0) ' A bizarre universe may be lurking in the shadows '
http://tinyurl.com/StrangeUniverse

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0-00-) 'ET could 'tickle' stars to create galactic internet' http://tinyurl.com/5msvwb

0-1) 'Do subatomic particles have free will?' http://tinyurl.com/58njs3
0-2) 'How big can a black hole grow?' http://tinyurl.com/5r7q9k
0-3) 'U.S. research networks link scientists to Large Hadron Collider' http://tinyurl.com/3m97h7
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0) Universe Models:---------------

0) 0. Electricity:----------------
'Electricity Powers the Universe' http://tinyurl.com/56w7aq

0) 1 "Quantum":---------------------
0) 1-1. 'Hawking 'close' to explaining universe's inflation' http://tinyurl.com/4fvz6z
0) 1-2. 'Quantum strangeness breaks the light barrier' http://tinyurl.com/5wumkp

0) 2. "Fractal";---------------------
0) 2-1. 'Galaxy map hints at fractal universe' http://tinyurl.com/3tuxl9
0) 2-2. 'Is the universe a fractal?' http://tinyurl.com/53w4jt

0) 3. "Swiss Cheese":----------------
' 'Swiss cheese' universe challenges dark energy ' http://tinyurl.com/4mnfhb

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1) Earth:-------------------------
'How to sing like a planet: Scientists say the Earth is humming. Not just noise, but a deep, astonishing music. Can you hear it?' http://tinyurl.com/5yfzy8

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00. 'Moving the Earth: a planetary survival guide' Jeff Hecht: Oct20,08, NewScientist.com news service: http://tinyurl.com/5ova43

: "" he clock is ticking inexorably toward doomsday even if we don't kill ourselves by poisoning the environment or overheating the planet. You see, there's a little problem with the Sun.

The Sun is slowly getting warmer as it burns the hydrogen in its core. In about 5 billion years, the Sun will begin evolving into a bloated red giant. Its outer gas shell will swell up, engulfing the Earth by the time it reaches its peak size and brightness 7 billion years from now. "


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0-) Universe Nature:---------------

0-0-) 'Scientists explore what happened before the universe's theoretical beginning' Robert S. Boyd, PhysOrg.com: McClatchy-Tribune Information Services, Sep22,08: http://tinyurl.com/4vv645

""When the huge subatomic-particle smasher under the Swiss-French border starts running, it's supposed to reveal what happened the instant after the big bang, the theoretical beginning of our universe 13.7 billion years ago.""

: " Respected scientists have proposed a flock of theories to describe what might have happened before the birth of our familiar universe of space and time.

The concepts have fanciful names such as "the big bounce," "the multiverse," "the cyclic theory," "parallel worlds," even "soap bubbles." Some propose the existence of multiple universes. Others hold that there's one universe that recycles itself endlessly, rather as Buddhists believe. Judeo-Christian theologians may have difficulty accepting any of these notions.

Most of the hypotheses are variations on an older idea that the universe has no beginning and no end, contrary to the big-bang theory, which says that our universe originated at a specific point and will end sometime in the distant future.

"Neither time nor the universe has a beginning or an end," two leading cosmologists, Paul Steinhardt of Princeton University and Neil Turok of Oxford University, wrote in their 2007 book, "Endless Universe: Beyond the Big Bang."

"The evolution of the universe is cyclic, with big bangs occurring once every trillion years or so, each one accompanied by the creation of new matter and radiation that forms new galaxies, stars, planets and presumably life," they wrote. "Ours is only the most recent cycle."

Some scientists contend that observational evidence may be found to back up the speculation. They say that no scientific theory can be considered valid until it's been tested.

"It is becoming increasingly clear that multiverse models grounded in modern physics can be empirically testable," Max Tegmark, a theoretical physicist at the University of Pennsylvania, Philadelphia, wrote in "Parallel Universes," a chapter in the 2003 book "Science and Ultimate Reality."

Some researchers hope that the Large Hadron Collider will provide evidence to support or refute these conjectures. They say the particle smasher might discover extra dimensions, beyond our familiar three spatial dimensions plus time. More dimensions are the basis of several pre-big-bang theories.

Michio Kaku, a professor of theoretical physics at the Graduate Center of the City University of New York, proposes that gravity, unlike light and matter, could travel between parallel universes and cast a "shadow" that scientists might be able to detect.

The shadow might take the form of "gravitational waves," faint ripples in the fabric of space and time caused by violent explosions such as the big bang. Detectors in the United States and Europe are seeking such waves, and in the future satellites will watch for evidence of them in space.

Turok says his cyclic theory predicts a "distinctive pattern of gravitational waves that is very different from the one expected in the big-bang theory ... and may prove or disprove our theory within the next few years."

Last August, ground and satellite observations revealed what appeared to be an enormous "hole in the universe," a mostly empty region of the sky, 900 million light-years wide - about 5 billion trillion miles - in the constellation Eridanus. Mersini-Houghton, a believer in multiple universes, interpreted the empty spot as the "footprint" of the gravitational tug of another, smaller universe parked at the edge of our own.

"It's like someone took a giant scoop and scooped all the matter away," she told the Columbia cosmology conference. "All these universes are interacting with each other."

Mersini-Houghton's interpretation of the "hole" is controversial and so far lacks independent confirmation.

The oldest and most popular of the pre-big-bang theories is the multiverse. As outlined by Martin Rees, the British astronomer royal, in his 1997 book, "Before the Beginning: Our Universe and Others," the theory declares that our universe is only one of many - perhaps an infinite number - of other worlds, each differing slightly from the others. These universes are continually forming new offspring, sprouting off from each other rather like soap bubbles.

The big bounce hypothesis - sometimes known as the big splat - contends that our universe was preceded by a twin that expanded to a certain limit, then contracted, collapsed and gave birth to our world. A leading proponent of this theory is Martin Bojowald, a theoretical physicist at Pennsylvania State University in University Park, who published it last year in the journal Nature.

In 2005, Kaku published a book titled "Parallel Worlds" in which he hypothesized that there may be millions of different, parallel universes, some that look like our own. They're invisible to us because they lie outside our universe. "

" According to Francisca Cho, a professor of Buddhism and East Asian religions at Georgetown, these pre-big-bang cosmologies are similar to the Hindu belief in a universe that cycles endlessly through creation and destruction. ""


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0-0-0-) 0. 'Mysterious New 'Dark Flow' Discovered in Space' Clara Moskowitz, space.com Staff Writer, posted Sep23,08 12:46pmET: Imaginova Corp: http://tinyurl.com/3ln6tn

: "" As if the mysteries of dark matter and dark energy weren't vexing enough, another baffling cosmic puzzle has been discovered.

Patches of matter in the universe seem to be moving at very high speeds and in a uniform direction that can't be explained by any of the known gravitational forces in the observable universe. Astronomers are calling the phenomenon "dark flow."

The stuff that's pulling this matter must be outside the observable universe, researchers conclude.

When scientists talk about the observable universe, they don't just mean as far out as the eye, or even the most powerful telescope, can see. In fact there's a fundamental limit to how much of the universe we could ever observe, no matter how advanced our visual instruments. The universe is thought to have formed about 13.7 billion years ago. So even if light started travelling toward us immediately after the Big Bang, the farthest it could ever get is 13.7 billion light-years in distance. There may be parts of the universe that are farther away (we can't know how big the whole universe is), but we can't see farther than light could travel over the entire age of the universe.

Mysterious motions

Scientists discovered the flow by studying some of the largest structures in the cosmos: giant clusters of galaxies. These clusters are conglomerations of about a thousand galaxies, as well as very hot gas which emits X-rays. By observing the interaction of the X-rays with the cosmic microwave background (CMB), which is leftover radiation from the Big Bang, scientists can study the movement of clusters.

The X-rays scatter photons in the CMB, shifting its temperature in an effect known as the kinematic Sunyaev-Zel'dovich (SZ) effect. This effect had not been observed as a result of galaxy clusters before, but a team of researchers led by Alexander Kashlinsky, an astrophysicist at NASA's Goddard Space Flight Center in Greenbelt, Md., found it when they studied a huge catalogue of 700 clusters, reaching out up to 6 billion light-years, or half the universe away. They compared this catalogue to the map of the CMB taken by NASA's Wilkinson Microwave Anisotropy Probe (WMAP) satellite.

They discovered that the clusters were moving nearly 2 million mph (3.2 million kph) toward a region in the sky between the constellations of Centaurus and Vela. This motion is different from the outward expansion of the universe (which is accelerated by the force called dark energy).

"We found a very significant velocity, and furthermore, this velocity does not decrease with distance, as far as we can measure," Kashlinsky told SPACE.com. "The matter in the observable universe just cannot produce the flow we measure."

Inflationary bubble

The scientists deduced that whatever is driving the movements of the clusters must lie beyond the known universe.

A theory called inflation posits that the universe we see is just a small bubble of space-time that got rapidly expanded after the Big Bang. There could be other parts of the cosmos beyond this bubble that we cannot see.

In these regions, space-time might be very different, and likely doesn't contain stars and galaxies (which only formed because of the particular density pattern of mass in our bubble). It could include giant, massive structures much larger than anything in our own observable universe. These structures are what researchers suspect are tugging on the galaxy clusters, causing the dark flow.

"The structures responsible for this motion have been pushed so far away by inflation, I would guesstimate they may be hundreds of billions of light years away, that we cannot see even with the deepest telescopes because the light emitted there could not have reached us in the age of the universe," Kashlinsky said in a telephone interview. "Most likely to create such a coherent flow they would have to be some very strange structures, maybe some warped space time. But this is just pure speculation."

Surprising find

Though inflation theory forecasts many odd facets of the distant universe, not many scientists predicted the dark flow.

"It was greatly surprising to us and I suspect to everyone else," Kashlinsky said. "For some particular models of inflation you would expect these kinds of structures, and there were some suggestions in the literature that were not taken seriously I think until now."

The discovery could help scientists probe what happened to the universe before inflation, and what's going on in those inaccessible realms we cannot see.

The researchers detail their findings in the Oct. 20 issue of the journal Astrophysical Journal Letters.

* Top 10 Strangest Things in Space
* Nearby Evidence for Dark Energy
* Does the Universe Have an Edge?


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0-0-0-) 1. 'Giant simulation could solve mystery of dark matter' Durham University news release: KurzweilAI.net, Nov6,08: http://tinyurl.com/5e95x2

: "" The international Virgo Consortium, a team of scientists, has used a massive computer simulation showing the evolution of a galaxy like the Milky Way to simulate detection of gamma rays given off by dark matter.


A map of the dark matter in six halos similar to that of the Milky Way. The brighter colors correspond to regions of higher density and indicate where most of the gamma rays are expected to be produced.

The researchers found that gamma rays produced when particles collided in areas of high dark matter density could be most easily detectable in regions of the Milky Way lying close to the Sun in the general direction of the galaxy's centre.

They suggest the Fermi Telescope should search in this part of the galaxy where they predict that gamma-rays from dark matter should glow in "a smoothly varying and characteristic pattern."

If Fermi does detect the predicted emission from the Milky Way's smooth inner halo, the Virgo team believes it might be able to see otherwise invisible clumps of dark matter lying very close to the Sun. ""


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0-0-0-0) ' A bizarre universe may be lurking in the shadows ' Anil Ananthaswamy, Mar4,2009: From issue 2698 of New Scientist magazine, page 28-31:
http://tinyurl.com/StrangeUniverse


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0-00-) 'ET could 'tickle' stars to create galactic internet' Marcus Chown: NewScientist.com news service, Sep8,08: http://tinyurl.com/5msvwb

Advanced extraterrestrial civilisations may be sending signals through space by "tickling" stars, new research suggests. The signalling would be the galactic equivalent of the internet.

"If it exists, it might be revealed by an analysis of already-existing stellar data," says John Learned of the University of Hawaii in Honolulu.

Learned and his colleagues have focused their attention on stars that vary regularly in brightness. Crucially, these "Cepheid variables" are so luminous they can be seen as far away as 60 million light years.

Jolting the star with a kick of energy – possibly by shooting it with a beam of high-energy particles called neutrinos – could advance the pulsation by causing its core to heat up and expand, they say.

That could shorten its brightness cycle – just as an electric stimulus to a human heart at the right time can advance a heartbeat. The normal and shortened cycles could be used to encode binary "0"s and "1"s.

The team says information could thus be shuttled around our galaxy's network of 500 or so Cepheids - and out as far as the Virgo cluster of galaxies.

"The beauty of the idea is that we have over a century of data on Cepheid variability so it is necessary only to look at it a new way to spot the signature of ET tampering," Learned told New Scientist.

Seth Shostak of the SETI Institute in Mountain View, California, thinks it is a "nice suggestion".

"But I'm inclined to think that positing the Cepheid scheme is like someone in Marconi's time predicting future radio broadcasters will use giant spark-gap transmitters to reach audiences in large cities," he says. "Better technology means higher efficiency, so using an entire star as the 'carrier' seems unlikely to me."


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0-1) 'Do subatomic particles have free will?' Julie Rehmeyer: Aug15,08, ScienceNews: http://tinyurl.com/58njs3

: If we have free will, so do subatomic particles, mathematicians claim to prove.


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0-2) 'How big can a black hole grow?' David Shiga: NewScientist.com news service, Sept3,08: http://tinyurl.com/5r7q9k


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0-3) 'U.S. research networks link scientists to Large Hadron Collider' Sep10,08: http://tinyurl.com/3m97h7 From Supercomputing Online: http://www.supercomputingonline.com

: "" ESnet, Internet2 and USLHCNet Provide Critical Link For Petabits Per Day of Data to U.S. Scientists Participating in the Large Hadron Collider Research: Today marked the first-ever attempt to circulate a beam of subatomic particles around the Large Hadron Collider (LHC), a gigantic particle accelerator spanning the French-Swiss border. The event represents a major milestone along the path towards a new understanding of the fundamental nature and origins of the universe. "

" The LHC has been nicknamed the “Big Bang Machine” because scientists will use it to recreate the cosmic conditions one trillionth of a second after the big bang, in hopes of finding insights into the origins of matter. It consists of a 27 kilometer tunnel and cathedral-sized caverns 100 meters underground. The accelerator magnets that guide the beams on their circular orbit are supercooled to a temperature just slightly above absolute zero, which is colder than outer space. It will accelerate matter to 99.999999% the speed of light, and recreate conditions a trillionth of a second after the big bang.

On October 15, 2008, Internet2 will provide a special peek behind the scenes at the LHC during its upcoming Fall 2008 Internet2 Member Meeting being held in New Orleans, LA—just a week before the expected first atomic collisions are anticipated at the LHC. The event will be netcast live for worldwide viewing. For more information, visit its Web site. ""


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0) Universes Models:--------------

0) 0. Electricity:----------------

'Electricity Powers the Universe' James P. Hogan LewRockwell.com Jul30,08 http://tinyurl.com/56w7aq

"" Electricity is an immensely more powerful force than gravity, and far more complex in the ways it interacts with matter. Yet modern astronomy remains wedded to a belief in gravity as the dominant mover and shaper of the universe, and seeks to explain new observations in terms that conceptually go back hundreds of years. James Hogan describes an emerging alternative theory that recognizes the important role played by electricity on cosmic scales, offering explanations based on principles that are well understood and demonstrable in laboratories, without need of recourse to unobserved, untestable physics or speculative mathematical abstractions. ""


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0) 1. "Quantum" Model:------------

0) 1-1. 'Hawking 'close' to explaining universe's inflation' Zeeya Merali: Jun28,08 NewScientistNews 2662: http://tinyurl.com/4fvz6z

: "" WHY was the big bang so very big? It has been a struggle to explain why the infant universe expanded so rapidly. But now Stephen Hawking at the University of Cambridge, and colleagues, think they are close to perfecting an answer - by treating the early cosmos as a quantum object with a multitude of alternative universes that gradually blend into ours.

The idea that the universe expanded at a blistering rate in the first 10-34 seconds after the big bang was proposed to explain why regions of the universe separated by vast distances have such a similar background temperature: before inflation occurred, these regions would have been close together with similar properties. But just why the universe inflated in the first place remains a mystery.

"There's no fundamental theory that can explain why inflation happened in our universe - it's just proposed as an ad hoc solution that explains ...
The complete article is 801 words long. ""


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0) 1-2. 'Quantum strangeness breaks the light barrier' Aug13,08: NewScientist.com news service: http://tinyurl.com/5wumkp

: "" IN THE weird world of quantum mechanics, the phenomenon of entanglement trumps all for strangeness - and maybe also for speed. Two entangled particles are so deeply linked that measuring one influences the other, regardless of the distance between them. In some interpretations, a signal passes between the two particles faster than light.

To test this idea, Daniel Salart and colleagues at the University of Geneva in Switzerland sent pairs of entangled photons to labs 18 kilometres apart. By measuring the properties of each photon in many of these pairs, the team showed that if superluminal signals are responsible for entanglement they must travel at more than 10,000 times the speed of light. The team favour an alternative idea - that a measurement on one photon instantly influences the other (Nature, DOI: 10.1038/nature07121).
From issue 2669 of New Scientist magazine, 13 August 2008, page 14 ""


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0) 2. "Fractal" Model:

0) 2-1. After "-22".
0) 2-2. 'Is the universe a fractal?' Amanda Gefter, Magazine issue 2594: Mar9,07: http://tinyurl.com/53w4jt

: "" Written across the sky is a secret, a hidden blueprint detailing the original design of the universe itself. The spread of matter throughout space follows a pattern laid out at the beginning of time and scaled up to incredible proportions by nearly 14 billion years of cosmic expansion. Today that pattern is gradually being decoded by analysing maps of the distribution of the stars, and what has been uncovered could shake modern cosmology to its foundations.

Cosmology is founded on the assumption that when you look at the universe at the vastest scales, matter is spread more or less evenly throughout space. Cosmologists call this a "smooth" structure. But a small band of researchers, led by statistical physicist Luciano Pietronero of the University of Rome and the Institute of Complex Systems, Italy, argues that this assumption is at odds with what we can see. Instead they claim that the galaxies ...

The complete article is 2410 words long. ""

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0) 2-1. 'Galaxy map hints at fractal universe' Amanda Gefter Jun225,08: NewScientist.com news service: http://tinyurl.com/3tuxl9

Related Articles:
* 'Swiss cheese' universe challenges dark energy 31 August 2007
* Is the universe a fractal? 09 March 2007
* Benoit Mandelbrot forecasts the future 18 November 2006

: "" Is the matter in the universe arranged in a fractal pattern? A new study of nearly a million galaxies suggests it is – though there are no well-accepted theories to explain why that would be so.

Cosmologists trying to reconstruct the entire history of the universe have precious few clues from which to work. One key clue is the distribution of matter throughout space, which has been sculpted for nearly 14 billion years by the competing forces of gravity and cosmic expansion. If there is a pattern in the sky, it encodes the secrets of the universe.

A lot is at stake, and the matter distribution has become a source of impassioned debate between those who say the distribution is smooth and homogeneous and those who say it is hierarchically structured and clumpy, like a fractal.

Nearly all physicists agree that on relatively small scales the distribution is fractal-like: hundreds of billions of stars group together to form galaxies, galaxies clump together to form clusters, and clusters amass into superclusters.

The point of contention, however, is what happens at even larger scales. According to most physicists, this Russian doll-style clustering comes to an end and the universe, on large scales, becomes homogeneous.

But a small team of physicists, including Francesco Sylos Labini of the Enrico Fermi Centre in Rome and Luciano Pietronero of the University of Rome argue that the data shows the opposite: the universe continues to look fractal as far out as our telescopes can see.


3D maps

The best data for looking at the galaxy distribution comes from the Sloan Digital Sky Survey (SDSS), which is constructing the largest 3D map of the universe. When completed, it will map the positions of about a million galaxies and quasars.

When SDSS data was released in 2004, physicists David Hogg of New York University and Daniel Eisenstein of the University of Arizona, both in the US, published an analysis of 55,000 luminous red galaxies suggesting that the fractal pattern smoothed out at scales over 200 million light years.

But Sylos Labini and Pietronero were not convinced. They believed that the apparent smoothing was an illusion caused by weak statistics – the smoothing seemed to occur at the largest scales the survey was capable of studying, where there were too few large regions to be able to reliably compare their densities, they said. Only a bigger map could resolve the debate.

Now, SDSS has released its sixth round of data, which plots the locations of roughly 800,000 galaxies and 100,000 quasars, bright objects powered by violent supermassive black holes.


Huge scales

According to their latest paper, which has been submitted to Nature Physics, Sylos Labini and Pietronero, along with physicists Nikolay Vasilyev and Yurij Baryshev of St Petersburg State University in Russia, argue that the new data shows that the galaxies exhibit an explicitly fractal pattern up to a scale of about 100 million light years.

And they say if the universe does become homogeneous at some point, it has to be on a scale larger than a staggering 300 million light years across. That's because even at that scale, they still observe large fluctuations – a cluster here, a void there – in the matter distribution.

Most cosmologists interpret such fluctuations as being no more significant than small waves on the surface of the sea, but Sylos Labini and colleagues say that these are more like tsunamis.


No model

Many cosmologists find fault with their analysis, largely because a fractal matter distribution out to such huge scales undermines the standard model of cosmology. According to the accepted story of cosmic evolution, there simply hasn't been enough time since the big bang nearly 14 billion years ago for gravity to build up such large structures.

What's more, the assumption that the distribution is homogeneous has allowed cosmologists to model the universe fairly simply using Einstein's theory of general relativity – which relates the shape of space to the distribution of matter.

Modelling a fractal universe with general relativity is possible in theory, but in reality it would be devilishly complicated. That would leave cosmologists without a working model, like acrobats without a net.


Relic radiation

To support the homogeneity assumption, cosmologists point to the smoothness of the cosmic microwave background (CMB), relic radiation from the nascent universe. The CMB is perfectly uniform up to one part in 100,000, suggesting the early universe was nearly homogeneous.

"The standard picture of a homogeneous universe on large scales is holding up very well when tested with very large-scale observations like those mapping the cosmic background radiation, X-rays and radio galaxies," says physicist Neil Turok of Cambridge University in the UK.

"If the observations of galaxies in optical surveys don't agree, there may be a number of possible explanations, without resorting to an extremely inhomogeneous, fractal universe," he told New Scientist.


Optical illusion?

But inferring the matter distribution from the CMB is not always simple. CMB maps show a 3D distribution projected onto a 2D surface, and it is possible for a clumpy 3D distribution to appear smooth when projected in 2D. The same is true of the X-ray background, which appears homogeneous in two dimensions. Finally, using galaxies that are bright at radio wavelengths is also problematic, as it is difficult to measure their distances accurately enough to pinpoint their positions in 3D.

So what could produce such a fractal pattern in galaxy surveys like Sloan? Some of the clumpiness may be a sort of optical illusion known as the Bull's-eye effect, says Adrian Melott of the University of Kansas in the US.

That's because nearby galaxies fall towards each other due to their mutual gravitational attraction – even as space itself expands. That movement can enhance the apparent clumpiness of matter in surveys like Sloan, since those surveys rely on measurements of the galaxies' velocities to determine their distance from Earth.


The wager

But according to their paper, Sylos Labini's team says the Bull's-eye effect is only relevant on very small scales, about 16 million light years and below, and has no influence on the clumpiness at the large scales in question.

Melott disagrees, saying it should magnify clumpiness at any scale. But he adds that the effect only "enhances structures that [already] exist".

What's at stake if the universe is indeed a fractal on the largest scales? Besides a radical rethink of the laws and history of the cosmos, researchers have placed something more down-to-Earth on the line.

More than a decade ago, Sylos Labini and Pietronero wagered a bet with physicist Marc Davis of the University of California, Berkeley, US. The bet, refereed by Turok, held that if the galaxy distribution turned out to be fractal beyond scales of approximately 50 million light years, Davis would owe Sylos Labini and Pietronero a case of California wine.

Should the fractal pattern begin to disintegrate at scales less than 50 million light years, Davis would receive a case of Italian wine – which some would say is a better deal. Turok has yet to declare a winner.

Cosmology - Keep up with the latest ideas in our special report. "

" There are 55 comments on 4 pages "


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0) 3. "Swiss Cheese" Model:-------------

' 'Swiss cheese' universe challenges dark energy ' Anil Ananthaswamy NewScientist.com news service: Aug31,07: http://tinyurl.com/4mnfhb

Related Articles
* Is dark energy an illusion? 30 March 2007
* Dark energy: Seeking the heart of darkness: 16 February 2007
* Giant space-time ripples may cause cosmic expansion: 18 March 2005
* Search New Scientist: Contact us

: "" Dark energy may not be needed to explain why the expansion of space appears to be speeding up. If our universe is like Swiss cheese on large scales – with dense regions of matter and holes with little or no matter – it could at least partly mimic the effects of dark energy, suggests a controversial new model of the universe.

In 1998, astronomers found that distant supernovae were dimmer, and thus farther away, than expected. This suggested the expansion of the universe was accelerating as a result of a mysterious entity dubbed dark energy, which appears to make up 73% of the universe.

But trying to pin down the nature of dark energy has proven extremely difficult. Theories of particle physics suggest that space does have an inherent energy, but this energy is about 10120 times greater than what is actually observed.

This has caused some cosmologists to look for alternative explanations. "I don't have anything against dark energy, but we ought to make all possible efforts to see whether we can avoid this exotic component in the universe," says Sabino Matarrese of the University of Padova in Italy.

So he and colleagues, including Edward Kolb of the Fermi National Accelerator Laboratory in Batavia, Illinois, US, decided to model the universe as having large-scale variations in density.

That contradicts the standard model of cosmology, which assumes that the universe is homogeneous on large scales. In the homogeneous model, known as the Friedmann-Robertson-Walker (FRW) universe, the effect of dark energy is to stretch space, thus increasing the wavelength of photons from the supernovae.


Testing assumptions

A similar effect was seen when the researchers added large-scale spherical holes to the FRW universe. They allowed the density of matter within each hole to vary with radius and found that in certain cases, photons travelling through under-dense voids had their wavelengths stretched, mimicking dark energy.

The extent of the effect depends on the exact location of the supernovae and how many under-dense regions the photons have to cross before reaching Earth. And Matarrese cautions that the deviations are not enough to explain away all of the observed dark energy. He says their model is still very preliminary: "We are very far away from getting the full solution."

Cosmologist Sean Carroll at Caltech in Pasadena, US, says the Swiss-cheese model is interesting and useful as a test of more mainstream theories. "The overwhelming majority of cosmologists think that the completely smooth approximation is a very good one," Carroll told New Scientist. "But if you want to have confidence that you are on the right track, you better not just make assumptions and cross your fingers, you better test it."


Up for debate

Astrophysicist Niayesh Afshordi of Harvard University in Cambridge, Massachusetts, US, is less impressed. Astronomical observations suggest that the density of matter in the universe is relatively smooth – and not like Swiss cheese – at scales of about 100 million light years or larger, he says. The new research, however, suggests that space is holey on scales of 500 million light years.

"The model is very inhomogeneous on scales that we observe as homogeneous," Afshordi told New Scientist. "What we can learn from the toy model is not really applicable to this universe, because the properties of this model are very different what we see in our universe."

However, team member Antonio Riotto of the University of Geneva in Switzerland argues that their Swiss-cheese model is realistic in the sense "that the universe is characterised by under-dense regions".

"We know that the universe has voids, you can debate about their size," he says. In fact, recent observations suggest that voids can extend across nearly a billion light years. Riotto says their model was worked out independently of that discovery, but "this observation is welcome by us".

Cosmology – keep up with the latest ideas in our special report. ""


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2) Earth:-----------------------

'How to sing like a planet: Scientists say the Earth is humming. Not just noise, but a deep, astonishing music. Can you hear it?' Mark Morford, SF Gate Columnist: Apr23,08: http://tinyurl.com/5yfzy8

: " Indeed, scientists now say the planet itself is generating a constant, deep thrum of noise. No mere cacophony, but actually a kind of music, huge, swirling loops of sound, a song so strange you can't really fathom it, so low it can't be heard by human ears, chthonic roars churning from the very water and wind and rock themselves, countless notes of varying vibration creating all sorts of curious tonal phrases that bounce around the mountains and spin over the oceans and penetrate the tectonic plates and gurgle in the magma and careen off the clouds and smack into trees and bounce off your ribcage and spin over the surface of the planet in strange circular loops, "like dozens of lazy hurricanes," as one writer put it.

It all makes for a very quiet, otherworldly symphony so odd and mysterious, scientists still can't figure out exactly what's causing it or why the hell it's happening. Sure, sensitive instruments are getting better at picking up what's been dubbed "Earth's hum," but no one's any closer to understanding what the hell it all might mean. Which, of course, is exactly as it should be. "