Scientists Mess with the Speed of Light...by getting light to go faster than, well, light.

Light Packets Slow to Jet Speed
By Michael Schirber
LiveScience Staff Writer
posted: 12 November, 2004
6:30 a.m. ET



The speed limit for light is 186,000 miles per second, but that doesn’t mean it can’t travel slower than that. Light moves through glass at about 60 percent of its maximum.



By bundling up light waves into special packets, physicists have proposed a stable way to slow light signals to one-millionth of the speed limit, which is about as fast as a jet aircraft.



Light has been made to go slower than this, even made to stand still. But most light packets will lose their shape when their speed is decreased -- a fact that hurts their application in the telecommunication industry.



The new packets, however, belong to a type of wave pattern, called a soliton, which has a robust shape that does not easily decay.



“Solitons were discovered in the 1800s as water waves that propagate without losing their height for miles and miles,” said Lu Deng of the National Institute of Standards and Technology.



Optical solitons generally are light waves that travel close to the speed of light. But Deng and his colleague, Ying Wu, have devised a way to make optical solitons that travel much slower, giving them more applicability in data transfer applications.



Currently, when an optical signal traveling down a fiber needs to be routed, it is converted to an electrical signal, so that it can be stored in a buffer, while the address is read. Once its destination is known, the signal is converted from electrical back to optical and sent on its way.



But Deng said that these conversions waste resources. It would be favorable to instead simply slow down the main signal while the address is read.



This is possible in tiny cells filled with gas atoms. By shining a laser into the cell, the speed of light can be tuned to whatever the researcher wants.



The problem, though, with these cells, or “optical buffers” as they are called, is that slowing down a wave can cause it to break up -- thereby losing the signal you are trying to send.



“People have been working for years on an optical buffer,” Deng said. “Unfortunately, they all have significant loss and terrible distortion.”



Deng compared the signal to an ice cream scoop sliding along a table. If it moves too slowly, the ice cream melts before it arrives at its destination.



But if the signal can be converted into a soliton it should maintain its shape. Deng and Wu have shown, in a recent issue of Physical Review Letters, how this soliton transformation can be done theoretically. They are now gearing up to prove their calculations in an experiment.



Continuing with the ice cream analogy, Deng said that a slow-moving soliton wave would be like a scoop with a metal shield.



“Analogies are never perfect,” he admitted. “The point is that [the non-soliton] degrades, but the soliton does not.”


[link to www.livescience.com]

thought travels faster than light.

electrons communicate instantly across billions of light years,

Physicists Bring Light to a Stop

By Joseph B. Verrengia
The Associated Press
posted: 11:48 am ET
19 January 2001



Physicists say they have brought light particles to a screeching halt, then revved them up again so that they could continue their journey at a blistering 186,000 miles (299,330 kilometers) per second.

The results are the latest in a growing number of experiments that manipulate light -- the fastest and most ephemeral form of energy in the universe.

Eventually, researchers hope to harness its speedy properties in the development of more powerful computers and other technologies that store information in light particles rather than electrons.

The experiments were conducted in separate laboratories in Cambridge, Massachusetts by groups led by Lene Vestergaard Hau of Harvard and the Rowland Institute of Science, and Ronald L. Waldsworth and Mikhail D. Lukin of the Harvard-Smithsonian Institute for Astrophysics.

The results will be published in upcoming issues of the journals Nature and American Physical Letters.

Physicists who did not participate in the experiments said the two research papers make an important contribution to understanding the properties of light. However, any practical applications are far off, they said.

"It´s a real first,´´ said Stanford physicist Stephen Harris, who collaborated on a 1999 experiment with Hau that slowed light to 38 miles (61 kilometers) per hour. "These experiments are beautiful science.´´

In the latest experiments, researchers took steps to not only slow light to a virtual crawl, but to stop it completely.

To do so, they created a trap in which atoms of gas were chilled magnetically to within a few-millionths of a degree of absolute zero and a consistency they described as "optical molasses.´´ Hau´s group used sodium atoms, while Waldsworth´s group used rubidium, an alkaline metal.

Normally, the gas atoms would absorb any light directed into the trap. The researchers solved this problem by aiming a "control´´ laser beam into the gas, which transformed it from opaque to a state known as electromagnetically induced transparency, or EIT.

Then they shined a second, probe laser that operated at a different frequency. When the wave of light particles hit the gas atoms, the particles slowed dramatically.

To stop the probe light entirely, the researchers waited until it had entered the vessel, encountered the gas atoms and imprinted a pattern into the orientation of the spinning atoms.

Then the scientists gradually reduced the intensity of the control beam.

As a result, the probe light dimmed and then vanished. But information in the light particles still was imprinted on the atoms of sodium and rubidium effectively freezing, or storing it, according to Hau.

Then the scientists gradually restored the control beam. The light that had been stored in the spinning atoms was reconstituted and continued its journey through the vessel.

"It´s as if you stretched a silk thread across a railroad track and a train vanishes into it,´´ said University of Colorado physicist Eric Cornell, who reviewed the Hau study for Nature.

"You wait and then -- Bam! -- the train reappears and goes zooming down the track,´´ Cornell said. "It´s not at all what you would expect from a pulse of light.´´

About 50 percent of the light -- and its information -- was retrieved in the regenerated light pulse, scientists said. That might not be good enough for a practical computing system, but it demonstrates how such a system might store and ship data.

"Nothing is ready to be picked up by the optical communications industry,´´ Harris said. "It needs further invention.´´

Whether either group actually stopped the light completely is open to some interpretation. The probe laser actually is a bundle of light waves that form a single wave. This is known to physicists as the group velocity; it is the light that your eye sees and a camera uses to record an image.

Does stopping the group velocity means that the individual light waves themselves were stopped? That´s a deeper quantum question, physicists said, but they considered the Cambridge groups´ claims to be valid.

"It is a real effect,´´ said Ben Stein of the American Physical Society.

Manipulating light´s properties is a subject of intensely competitive research. In July, physicists in Princeton, New Jersey apparently pushed a laser pulse through a vapor of cesium atoms so it traveled faster than the conventional speed of light.

[link to www.space.com]

Blue Skies Only In the Eye of the Beholder
By Michael Schirber
LiveScience Staff Writer
posted: 19 July 2005
11:28 am ET



The sky is blue -- physicists tell us -- because blue light in the Sun´s rays bends more than red light. But this extra bending, or scattering, applies just as much to violet light, so it is reasonable to ask why the sky isn´t purple.

The answer, explained fully for the first time in a new scientific paper, is in the eye of the beholder.

Blue Sky, Red Sunset


Blue light has a short wavelength, and the particles in the air scatter it around, making the sky appear blue. Red light has a longer wavelength, which acts more strongly and is not scattered as much. Sunsets are red because in the evening, the light has more atmosphere to pass through to get to your eye, and only the strong red light can make it. The atmosphere in the illustration above is exaggerated in relation to the Earth to show the difference.







"The traditional way that people teach this subject is that sunlight is scattered -- more so for shorter wavelengths than for longer ones," says Glenn Smith, an engineering professor at Georgia Tech. "The other half of the explanation is usually left out: how your eye perceives this spectrum."

While writing a physics textbook some years ago, Smith noticed that physiology usually gets short shrift, even though the spectrum of sky light -- when analyzed -- is about equal parts violet and blue.

Smith has written an article for the July issue of the American Journal of Physics that puts the physics of light together with the physiology of human vision.

"This is nothing that people who work with eyes haven´t known for a long time," Smith told LiveScience. "I just had not seen it all in one place before."

The physical explanation for the blueness of the sky is attributed to the work of Lord Rayleigh in the 19th Century.

As a common prism reveals, sunlight is made of all the colors of the rainbow. When light from the Sun enters Earth´s atmosphere, it is scattered, or deflected, by molecules in the atmosphere -- primarily nitrogen and oxygen.

Shorter wavelengths (blue and violet) are scattered more than longer wavelengths (red and yellow). So as we look in a direction of the sky away from the Sun, we see those wavelengths that are bent the most.

The light of day is actually a complex spectrum of many different wavelengths, but it is dominated by light with wavelengths between 400 nanometers (violet) and 450 nanometers (blue). A nanometer is one billionth of a meter.

Image Galleries


Sunrises & Sunsets


Sky Scenes


Curious Clouds







The human eye is sensitive to light between roughly 380 and 740 nanometers. On a typical retina, there are 10 million rods for sensing low light levels and 5 million cones for detecting color.

Each cone contains pigments that restrict the range of wavelengths that the cone responds to. There are three varieties of cones for long, medium and short wavelengths.

"You need all three of them to see color correctly," Smith explained.

The peak response for the long cones is at 570 nanometers (yellow), medium at 543 nanometers (green), and short at 442 nanometers (between violet and blue). But the three cones are sensitive over broad, overlapping wavelength ranges, which means two different spectra can cause the same response in a set of various cones.

A good example of this is yellow. There is a certain narrow range of wavelengths that we might call "pure" yellow (or another for "pure" blue, and so on). However, the same set of cones that reacts to a light of pure yellow also responds to the superposition of pure red and pure green light.

Two spectra that have the same cone response are called metamers. Smith stressed that this only concerns the neural signal coming out of the eye -- long before any processing by the brain.

"In previous research, people excised cones from the eyes of dead people and measured the response to different spectra," he said.

The same "trick" that makes red and green turn into yellow is happening in the sky. But in this case, the sky´s combination of violet and blue elicits the same cone response as pure blue plus white light, which is an equal mixture of all the colors.

"Your eye can´t tell the difference between that complex spectrum and one that is a mixture of pure blue and white," Smith said.

In other animals, the sky color is undoubtedly different. Outside of humans and some other primates, most animals have only two types of cones instead of three (dichromatic vs. trichromatic).

Honeybees and some birds see at ultraviolet wavelengths that are invisible to humans.

[link to www.livescience.com]

New Theory: How to Make Objects Invisible
By Robert Roy Britt
LiveScience Senior Writer
posted: 28 February 2005
01:00 pm ET



High-tech cloaking machines could one day render very small objects nearly invisible and perhaps improve military stealth technology, scientists said Monday.

The idea is straight out of science fiction -- cloaking technology made Romulan spaceships disappear in Star Trek. A humble version of the device could become a reality, according to Nader Engheta and Andrea Alu of the University of Pennsylvania.

But don´t expect to hide yourself or your spaceship anytime soon, at least not in the standard sense of invisible. In practical terms, the research is more likely to lead to improved technical and research devices, and even these applications are years away.

How it would work

The proposal involves using plasmons -- tiny electronic excitations on the surfaces of some metals -- to cancel out the visible light or other radiation coming from an object.

"A proper design … may induce a dramatic drop in the scattering cross-section, making the object nearly invisible to an observer," Nader and Alu write in a scientific paper that was made available to the public Feb. 14.

But cloaking ability would depend on an object´s size, so that only with very small things -- items that are already microscopic or nearly so -- could the visible light be rendered null. A human could be made impossible to detect in longer-wavelength radiation such as microwaves, but not from visible light.

A spaceship might be made transparent to radio waves or some other long-wavelength detector.

The idea is in an infant stage but appears not to violate any laws of physics, according to an article Monday in [email protected], an online companion to the journal Nature, which provided advance copies of the story to reporters.

"The concept is an interesting one, with several important potential applications," John Pendry, a physicist at Imperial College in London in the UK, told the publication. "It could find uses in stealth technology and camouflage."

But Engheta, co-developer of the idea, said such applications can´t even be considered yet.

"Things like airplanes are very complex objects -- complex shape and complex materials -- and I do not know to what extent our concept can be applicable to that," Engheta told LiveScience. "We are still in the conceptual stage, and there are several important questions that have to be answered before any practical scenario can be considered."

Plasmons are real

You´ve seen cloaking technology at work on television, when blue backgrounds are used to make a person invisible. Alu and Engheta envision something far more sophisticated.

Small Stuff


Micromachines

Microscopic Images
as Art





Objects are visible in the optical range because they reflect light, a process scientists call scattering. Objects absorb light, too, and what is absorbed is not seen. The sky is blue because the atmosphere scatters blue light more than red.

A plasmonic cloaker would resonate with a particular wavelength of light, so that the wavelength would not scatter.

Plasmons are real, a product of a strange characteristic of light, which is made up of both particles and waves. Plasmons are created when electrons on the surface of a metallic material move in rhythm. They have other odd properties.

Back in 1998, researchers led by Thomas Ebbesen of the Louis Pasteur University in Strasbourg, France shone light on a sheet of gold foil that contained millions of tiny holes. The holes were smaller than the wavelength of the light, and Ebbesen expected no light to get through. Amazingly, more light came out the other side than what hit the holes.

Follow-up research found that plasmons -- jittery little waves on the surface of the metal -- were snagging light and stuffing it through the holes. "When the energy and momentum of the photons match the energy and momentum of the plasmons, the photons are absorbed and radiated again on the other side," according to an article in the May 1998 edition of Photonics Spectra magazine.

Reality sets in

Engheta and Alu say objects coated with perhaps loops or coils of silver or gold might do the trick.

But there are many hurdles. It is not clear how even a small object could disappear in daylight, which itself contains many different wavelengths, or colors, of light. Presumably a plasmonic device would have to be built to cloak each wavelength.

Anything not perfectly ball-shaped presents additional problems. The researchers´ calculations suggest "homogeneous spherical objects" in the nanoscale range -- really, really small -- could be rendered optically invisible.

Practically speaking, the technology, if developed, might be used in antiglare materials or to improve microscopic imaging in about five years, Engheta said.

[link to www.livescience.com]

Sculptor~

Astronomy Picture of the Day
Discover the cosmos!

2005 August 20

The Stars of NGC 300

Like grains of sand on a cosmic beach, individual stars of large spiral galaxy NGC 300 are resolved in this sharp image from the Hubble Space Telescope´s Advanced Camera for Surveys (ACS). The inner region of the galaxy is pictured, spanning about 7,500 light-years. At its center is the bright, densely packed galactic core surrounded by a loose array of dark dust lanes mixed with the stars in the galactic plane. NGC 300 lies 6.5 million light-years away and is part of a group of galaxies named for the southern constellation Sculptor. Hubble´s unique ability to distinguish so many stars in NGC 300 can be used to hone techniques for making distance measurements on extragalactic scales.

[link to antwrp.gsfc.nasa.gov]

hmmm...

[link to www.selo-mira.de]

[link to www.selo-mira.de]

thought is faster than light

HEY YOU BEAT ME TO IT

relatively

YOU ARE WHERE YOUR ATTENTION IS

too


YES to this thread
relativity is a theory too ya know
IT IS DARK IN OUTER SPACE?
hmmm
if a halogen lamp falls in the woods

Mystery Solved: How Plants Know When to Flower
By Robert Roy Britt
LiveScience Senior Writer
posted: 11 August 2005
02:01 pm ET



Scientists have known since the 1930s that plants sense the length of the days and, somehow, use that information to decide when to flower.

Russian scientists back then speculated that a mysterious substance must be transported from leaves to shoot tips, stimulating the formation of flower buds. They called the mystery chemical "florigen."

A trio of new studies announced today seem to reveal how it works, including why flowers spring forth in certain spots on a plant.

"We have now shown that a gene called FT, which is active in the leaf and whose activity is regulated by the day length, produces a messenger molecule that is transported to the shoot tip," said Ove Nilsson at the Umea Plant Science Center at the Swedish University of Agricultural Sciences.

Separate research, conducted by a different team, reveals how the messenger molecule works to activate the "gene programs" that lead to the formation of floral buds.

In short, proteins are formed and they talk to other proteins that exist only at the future locations of buds, and flowers are born at just the right time in a preprogrammed location.

Temperature and soil conditions play a role in the timing, too, the scientists said.

"Together these data show that the messenger molecule produced by FT either is the elusive florigen, or is a very important component of florigen," Nilsson told LiveScience.

And why does this matter to scientists?

Daffodils bloom in spring as the days get longer. Roses wait until summer. Rice, on the other hand, flowers in the fall as the days shorten. Nature does fine, of course, but humans sometimes want to fool her.

"It is interesting to speculate that this finding could be used to make early flowering rice," Nilsson said. "Since many of the high yielding varieties are late flowering this could in certain parts of the world allow the production of more than one harvest per year."

The findings are reported by the journal Science.

It has not been clear how plants combine all the information needed to build a flower, writes Spanish researcher Miguel Blazquez in an analysis in the journal. The new studies "reveal the molecular mechanism by which this integration is achieved," he said.

[link to www.livescience.com]

Flower Power: See Amazing Images ....
[link to www.livescience.com]

....The Flower That Thought It Was A Supernova:...flower:
[link to light-bruised.net]

High Noon and the Naked Lady
[link to www.livescience.com]

World´s Largest Flower Skips Sex....
[link to www.livescience.com]

The centre of the Milky Way...

[link to www.eso.org]
[link to www.eso.org]

Ice Lightning
[link to www.livescience.com]

The Science of Lightning
[link to www.livescience.com]

Trees Hold Record of Ancient....
[link to www.livescience.com]

leaf-
[link to www.bahai.ch]

Rex-leaf-
[link to gallery.hd.org]

brain/neurons-
[link to www.medicalillustration.net]
[link to www.willamette.edu]
[link to www.wellesley.edu]
[link to www.pfizer.com]
[link to sv.epfl.ch]
[link to www.pueblo.gsa.gov]

Neurons


• Building blocks of the brain

[link to www.morphonix.com]

Bar at Milky Way´s heart revealed
18:03 16 August 2005
NewScientist.com news service
Maggie McKee



image
[link to www.newscientist.com]

The massive new survey of stars reveals a definitive bar feature at the centre of the Milky Way, some 27,000 light years in length (Artist´s impression: NASA/JPL-Caltech/R Hurt, SSC/Caltech)Related Articles



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Ed Churchwell, University of Wisconsin
Spitzer Space Telescope
Astrophysical Journal Letters
The Milky Way is not a perfect spiral galaxy but instead sports a long bar through its centre, according to new infrared observations from NASA´s Spitzer Space Telescope.

Galaxies come in a wide variety of shapes usually thought to be produced by gravitational interactions with nearby objects. Some spiral galaxies look like pinwheels, with their arms curving out from a central bulge, while others have a straight bar at their centres.

Radio telescopes detected gas that hinted at a bar at the heart of the Milky Way in the late 1980s. A decade later, observations with the near infrared survey 2MASS bolstered the case for a bar, but dust in the centre of the galaxy obscured the observations.

Now, astronomers have used Spitzer to peer through that dust at slightly longer wavelengths, observing 30 million stars in the galactic plane in the region around the centre of the galaxy.

They found that the central bar was much longer than previous observations had suggested - reaching about half the distance between the galaxy´s centre and our Sun. The bar is estimated to stretch a total of about 27,000 light years from end to end.

"It is a major component of our galaxy and has basically remained hidden until now," says team member Ed Churchwell, an astronomer at the University of Wisconsin in Madison, US. "The fact that it´s large means it´s going to have a major effect on the dynamics of the inner part of our galaxy."

Bar food
Stars in the spiral arms circle the galaxy in roughly circular orbits. But the old, red stars in the bar appear to be on more elliptical paths that take them more directly towards and away from the galaxy´s core, where a colossal black hole is thought to lurk.

"This bar probably does carry matter into the centre of the galaxy and feeds the black hole," Churchwell told New Scientist.

But it is still not clear what the discovery reveals about the Milky Way´s past. "I don´t think anybody really fully understands how bars are formed," says Churchwell. "What we do know is that it appears there are so many barred galaxies they must be rather stable. Astronomers have to come up with some kind of model that can explain the stability of these structures."

The team will publish its results in an upcoming issue of Astrophysical Journal Letters and has requested more time on Spitzer to study the innermost part of the Milky Way.



[link to www.newscientist.com]

"This seeming paradox can be resolved because a pulse of light is actually made up of many separate frequency components, each of which moves at their own velocities."

Nonsense. Frequency is a measure of the photon´s energy, not its speed.

all techniques can be shown not only in a mathmatical formula,

It should be able to be told in a visual and aural way.

Like the doppler effect

can someone point us to a visual representaion of this process.

so what makes the light speed up´

so what makes the light stop.

I see posts,

no math at the least

and I see posts,

that can´t even show it visually and aurally if needed in one way or the other.

NASA TV does it.

come on guys, if your gonna change the universe show us what it looks like

just kidding.

but serious.

if your going to demonstrate an effect in "nature" then you have to be able to "show" it and how if effects everything around it.

thats called proof

at the smallest definition.