Dark Fluid: Dark Matter And Dark Energy May Be Two Faces Of Same Coin

Astronomers at the University of St Andrews believe they can "simplify the dark side of the universe" by shedding new light on two of its mysterious constituents.

Dr HongSheng Zhao, of the University's School of Physics and Astronomy, has shown that the puzzling dark matter and its counterpart dark energy may be more closely linked than was previously thought.

Only 4% of the universe is made of known material - the other 96% is traditionally labelled into two sectors, dark matter and dark energy.

A British astrophysicist and Advanced Fellow of the UK's Science and Technology Facilities Council, Dr Zhao points out, "Both dark matter and dark energy could be two faces of the same coin.

"As astronomers gain understanding of the subtle effects of dark energy in galaxies in the future, we will solve the mystery of astronomical dark matter at the same time. "

Astronomers believe that both the universe and galaxies are held together by the gravitational attraction of a huge amount of unseen material, first noted by the Swiss astronomer Fritz Zwicky in 1933, and now commonly referred to as dark matter.

Dr Zhao reports that, "Dark energy has already revealed its presence by masking as dark matter 60 years ago if we accept that dark matter and dark energy are linked phenomena that share a common origin."

In Dr Zhao's model, dark energy and dark matter are simply different manifestations of the same thing, which he has considered as a 'dark fluid'. On the scale of galaxies, this dark fluid behaves like matter and on the scale of the Universe overall as dark energy, driving the expansion of the Universe. Importantly, his model, unlike some similar work, is detailed enough to produce the same 3:1 ratio of dark energy to dark matter as is predicted by cosmologists.

Efforts are currently underway to hunt for very massive dark-matter particles with a variety of experiments. The Large Hadron Collider (LHC) at the European Organization for Nuclear Research (CERN) in Geneva is a particle accelerator that amongst other objectives, could potentially detect dark matter particles.

According to Dr Zhao, these efforts could turn out to be fruitless. He said, "In this simpler picture of universe, the dark matter would be at a surprisingly low energy scale, too low to be probed by upcoming Large Hadron Collider.

"The search for dark-matter particles so far has concentrated on highly-energetic particles. If dark matter however is a twin phenomenon of dark energy, it will not show up at instruments like the LHC, but has been seen over and over again in galaxies by astronomers."

However, the Universe might be absent of dark-matter particles at all. The findings of Dr Zhao are also compatible with an interpretation of the dark component as a modification of the law of gravity rather than particles or energy.

Dr Zhao concluded. "No matter what dark matter and dark energy are, these two phenomena are likely not independent of each other."

Background

Theories of the physics of gravity were first developed by Isaac Newton in 1687 and refined by Albert Einstein’s theory of General Relativity in 1905 which stated that the speed of gravity is equal to the speed of light. However, Einstein was never fully decided on whether his equation should add an omnipresent constant source, now called dark energy in general.

Astronomers following Fred Zwicky have also speculated additional sources to Einstein's equation in the form of non-light emitting material, called dark matter in general. Apart from very light neutrinos neither dark sources have been confirmed experimentally.

Dr Zhao and his collaborators' findings have recently been published by Astrophysical Journal Letters in December 2007, and Physics Review D. 2007.

Magnetic Portals Connect Sun And Earth

From here.

During the time it takes you to read this article, something will happen high overhead that until recently many scientists didn't believe in. A magnetic portal will open, linking Earth to the sun 93 million miles away. Tons of high-energy particles may flow through the opening before it closes again, around the time you reach the end of the page.

"It's called a flux transfer event or 'FTE,'" says space physicist David Sibeck of the Goddard Space Flight Center. "Ten years ago I was pretty sure they didn't exist, but now the evidence is incontrovertible."

Indeed, today Sibeck is telling an international assembly of space physicists at the 2008 Plasma Workshop in Huntsville, Alabama, that FTEs are not just common, but possibly twice as common as anyone had ever imagined.

Researchers have long known that the Earth and sun must be connected. Earth's magnetosphere (the magnetic bubble that surrounds our planet) is filled with particles from the sun that arrive via the solar wind and penetrate the planet's magnetic defenses. They enter by following magnetic field lines that can be traced from terra firma all the way back to the sun's atmosphere.

"We used to think the connection was permanent and that solar wind could trickle into the near-Earth environment anytime the wind was active," says Sibeck. "We were wrong. The connections are not steady at all. They are often brief, bursty and very dynamic."

Several speakers at the Workshop have outlined how FTEs form: On the dayside of Earth (the side closest to the sun), Earth's magnetic field presses against the sun's magnetic field. Approximately every eight minutes, the two fields briefly merge or "reconnect," forming a portal through which particles can flow. The portal takes the form of a magnetic cylinder about as wide as Earth. The European Space Agency's fleet of four Cluster spacecraft and NASA's five THEMIS probes have flown through and surrounded these cylinders, measuring their dimensions and sensing the particles that shoot through. "They're real," says Sibeck.

Now that Cluster and THEMIS have directly sampled FTEs, theorists can use those measurements to simulate FTEs in their computers and predict how they might behave. Space physicist Jimmy Raeder of the University of New Hampshire presented one such simulation at the Workshop. He told his colleagues that the cylindrical portals tend to form above Earth's equator and then roll over Earth's winter pole. In December, FTEs roll over the north pole; in July they roll over the south pole.

Sibeck believes this is happening twice as often as previously thought. "I think there are two varieties of FTEs: active and passive." Active FTEs are magnetic cylinders that allow particles to flow through rather easily; they are important conduits of energy for Earth's magnetosphere. Passive FTEs are magnetic cylinders that offer more resistance; their internal structure does not admit such an easy flow of particles and fields. (For experts: Active FTEs form at equatorial latitudes when the IMF tips south; passive FTEs form at higher latitudes when the IMF tips north.) Sibeck has calculated the properties of passive FTEs and he is encouraging his colleagues to hunt for signs of them in data from THEMIS and Cluster. "Passive FTEs may not be very important, but until we know more about them we can't be sure."

There are many unanswered questions: Why do the portals form every 8 minutes? How do magnetic fields inside the cylinder twist and coil? "We're doing some heavy thinking about this at the Workshop," says Sibeck.

Meanwhile, high above your head, a new portal is opening, connecting your planet to the sun.

FusionMan: Man Flying a Reality

Jet man ready for cross-Channel attempt after 'awesome' test flight

From here.

Pilot Yves Rossy landed safely yesterday after reaching speeds of 180mph strapped to a jet-powered wing

• James Randerson, science correspondent
• guardian.co.uk,
• Thursday August 21 2008 17:58 BST
• Article history

Yves Rossy soars over Switzerland yesterday strapped to a jet-powered wing. The flight was a test run for a cross-Channel attempt next month

A Swiss daredevil's bid to cross the English Channel propelled by a jet-powered wing strapped to his back moved a step closer yesterday with a successful 36km test flight over Switzerland.

The flight proves that his jet-powered wing can take him far enough to make it across the channel from Calais to Dover. He hopes to make the crossing on 24 September if the weather is suitable.

Yves Rossy – who calls himself FusionMan – jumped from a plane above the Swiss town of Bex and reached speeds of up to 180mph during his 12 minutes of jet-powered flight before landing at an airfield in Villeneuve. Rossy first unveiled his jet-powered wing in May with an 8-minute aerobatic display over the Alps.

Rossy and team after his flight

"Everything went well, it was awesome," said Rossy after the flight. "It's my longest flight with this wing. If there are no technical problems, it's OK for the English Channel. I can't wait for this next challenge!"

His attempt had originally been thwarted by a collection of technical failures, including a leaking gas tank and two aborted flights during which the engines stopped within seconds of jumping from his support plane. He blamed these failures – which forced him to deploy his parachutes early – on "electronic interference problems".

The successful flight involved him jumping out of the aircraft at 2,300m, flying horizontally under jet power from a height of 1,700m and then switching off the jet engines before deploying two parachutes at 1500m and 1200m.

The wing does not include moving parts such as flaps to control direction, but Rossy is able to steer by shifting his weight and moving his head.

When he reached the ground he still had 2 litres of fuel left in his wing, suggesting that he would have some margin for error during the cross-channel flight.

Rossy is a former military pilot. His channel flight will be streamed live on the National Geographic Channel.

Holography: The Future of Telecommunication

From here

al gore hologram - live earth tokyo '07

Al Gore launched Live Earth Tokyo in a high-tech, virtual way – as a hologram using Musion Eyeliner Holographic Projection. After a stirring introduction by Lumi, the virtual-reality singer of Genki Rockets, a head-to-toe-likeness of the former U.S. Vice President materialized on stage.

He shared urgent yet hopeful words to the crowd gathered at Makuhari Messe. The holographic Gore had an expression of amazement as he delivered the following words:
What an amazing world we live in – I love it that I can stand here on this stage in Tokyo and speak to you in holographic form. It is astounding that in just these recent few decades we have invented technologies that enable us to connect and instantly communicate our ideas and intentions with people on the other side of the globe.

Because of the communication channels and technologies now available to us, this venue is, at this moment, connected to the entire world. You are all communicating to well over 2 billion people right now – including all the Live Earth audiences in Sydney, Shanghai, Johannesburg, Hamburg, London, Rio de Janeiro and New York and the broadcast audience who will be watching on television and the Internet in over 100 countries.

musion eyeliner 3d technical

Musion Eyeliner System incorporates some very simple video principles and all equipment used is readily available in both the American and European rental markets.

The primary components of a Eyeliner set up are:

• A video projector, preferably DLP with an HD card/minimum native resolution of 1280 x 1024 and brightness of 5000+ lumens.
• For smaller cabinet installations, a high quality TFT Plasma or LCD screen can also be used.
• A hard-disc player with 1920 x 1080i HD graphics card, Apple or PC video server, DVD player.
• Musion Eyeliner Foil + 3D set/drapes enclosing 3 sides
• Lighting and audio as required
• Show controller (on site or remote)

Subjects are filmed in HDTV and broadcast on to the foil through HDTV projection systems, driven by HD Mpeg2 digital hard disc players, or uncompressed full HDTV video/Beta-Cam players.

The setup is erected in either a bespoke cabinet or a self contained four legged ground support. Alternatively, the foil can be stretched into a truss framework and flown from its own hanging points.

In either configuration, Eyeliner allows for a full working stage or set to be constructed behind the foil. In so doing live actors or performers, as well as virtual images are able to interact with other projected images in such a way that it appears to the watching audience that all of the objects they are seeing are in stage.

It is therefore quite conceivable to have a live performer sing a duet with a ‘virtual’ partner, a cartoon character or even his/hers projected double.

All the images used on an Eyeliner system are three-dimensional images, but projected as two-dimensional images (2D/3D) into a 3D stage set. The mind of the audience created the 3D illusion. This means that production costs are minimal, needing only the single camera lens for filming and a single projector for the playback – hence the phrase ‘Glasses-free viewing’.

Physicists have 'solved' mystery of levitation

In theory the discovery could be used to levitate a person

Levitation has been elevated from being pure science fiction to science fact, according to a study reported today by physicists.

In earlier work the same team of theoretical physicists showed that invisibility cloaks are feasible.

Now, in another report that sounds like it comes out of the pages of a Harry Potter book, the University of St Andrews team has created an 'incredible levitation effects’ by engineering the force of nature which normally causes objects to stick together.

Professor Ulf Leonhardt and Dr Thomas Philbin, from the University of St Andrews in Scotland, have worked out a way of reversing this pheneomenon, known as the Casimir force, so that it repels instead of attracts.

Their discovery could ultimately lead to frictionless micro-machines with moving parts that levitate But they say that, in principle at least, the same effect could be used to levitate bigger objects too, even a person.

The Casimir force is a consequence of quantum mechanics, the theory that describes the world of atoms and subatomic particles that is not only the most successful theory of physics but also the most baffling.

The force is due to neither electrical charge or gravity, for example, but the fluctuations in all-pervasive energy fields in the intervening empty space between the objects and is one reason atoms stick together, also explaining a “dry glue” effect that enables a gecko to walk across a ceiling.

Now, using a special lens of a kind that has already been built, Prof Ulf Leonhardt and Dr Thomas Philbin report in the New Journal of Physics they can engineer the Casimir force to repel, rather than attact.

Because the Casimir force causes problems for nanotechnologists, who are trying to build electrical circuits and tiny mechanical devices on silicon chips, among other things, the team believes the feat could initially be used to stop tiny objects from sticking to each other.

Prof Leonhardt explained, “The Casimir force is the ultimate cause of friction in the nano-world, in particular in some microelectromechanical systems.

Such systems already play an important role - for example tiny mechanical devices which triggers a car airbag to inflate or those which power tiny 'lab on chip’ devices used for drugs testing or chemical analysis.

Micro or nano machines could run smoother and with less or no friction at all if one can manipulate the force.” Though it is possible to levitate objects as big as humans, scientists are a long way off developing the technology for such feats, said Dr Philbin.

The practicalities of designing the lens to do this are daunting but not impossible and levitation “could happen over quite a distance”.

Prof Leonhardt leads one of four teams - three of them in Britain - to have put forward a theory in a peer-reviewed journal to achieve invisibility by making light waves flow around an object - just as a river flows undisturbed around a smooth rock.

Invisibility cloak

From here

Researchers at the University of California in Berkeley have developed a material that can bend light around 3D objects making them "disappear".

The materials do not occur naturally but have been created on a nano scale, measured in billionths of a metre.

The team says the principles could one day be scaled up to make invisibility cloaks large enough to hide people.

Stealth operations

The findings, by scientists led by Xiang Zhang, were published in the journals Nature and Science.

The light-bending effect relies on reversing refraction, the effect that makes a straw placed in water appear bent.

Previous efforts have shown this negative refraction effect using microwaves—a wavelength far longer than humans can see.

The new materials instead work at wavelengths around those used in the telecommunications industry—much nearer to the visible part of the spectrum.

Two different teams led by Zhang made objects made of so-called metamaterials—artificial structures with features smaller than the wavelength of light that give the materials their unusual properties.

One approach used nanometre-scale stacks of silver and magnesium fluoride in a "fishnet" structure, while another made use of nanowires made of silver.

Light is neither absorbed nor reflected by the objects, passing "like water flowing around a rock," according to the researchers. As a result, only the light from behind the objects can be seen.

Cloak and shadow

The fine structure of the material gives it light-bending abilities

"This is a huge step forward, a tremendous achievement," says Professor Ortwin Hess of the Advanced Technology Institute at the University of Surrey.

"It's a careful choice of the right materials and the right structuring to get this effect for the first time at these wavelengths."

There could be more immediate applications for the devices in telecommunications, Prof Hess says.

What's more, they could be used to make better microscopes, allowing images of far smaller objects than conventional microscopes can see.

And a genuine cloaking effect isn't far around the corner.

"In order to have the 'Harry Potter' effect, you just need to find the right materials for the visible wavelengths," says Prof Hess, "and it's absolutely thrilling to see we're on the right track."