Black Hole Thursdays.

Astronomers have for the first time developed a technique to view rapidly spinning disks of gas found near black holes.

Their observations allowed them to confirm the that the electromagnetic spectra of these accretion disks match what astronomers have long predicted, giving a boost of hard evidence to current quasar formation theory.

The team of researchers gazed into the night on Mauna Kea in Hawaii, looking through the United Kingdom Infrared Telescope. They were able to measure the spectrum of the accretion disk by getting rid of extra, interfering light, using a polarizing filter attached to the telescope.

Why exactly are polarized filters so special? Well, they aren't. It is the way that accretion disks emit light that lets the filter do its job. Accretion disks emit non-polarized light that doesn't care how its electrical field is aligned, known as direct light. But a small amount of accretion disk light reflects off gas very close to the black hole- this light is polarized. By only analyzing polarized light, researchers are able to ignore all the direct-light emitting irrelevant stuff, like dust particles and ionized gas.

Quasars are extremely bright, distant objects that also emit frenzied, massive amounts of energy. They are powerful, but until now no one has been able show that accretion disks falling toward black holes, particular near the horizon or black hole boundary, is the source of much that power.
Read the rest of the post . . .

And Then There Was Light...Emitting Diodes

They've been around since the 1960s (mostly in traffic signals), but Light Emitting Diodes(LEDs) are lighting up the future.

I could rave about all the neat characteristics these luminous materials have, but only two are really important: LED lights only need to be replaced every 15 years, and they could potentially reduce the amount of electricity we consume by 10 percent, if used widely.

What more could one want in a lighting source? Unfortunately, there is a "dark" side to LEDs. They are painstakingly expensive. That's because a layer of sapphire is currently used in manufacturing LEDs.

While the idea of lighting your living room with dazzling gems might be attractive, it certainly isn't conducive to mass production. Researchers at Purdue University in Indiana have solved that problem, by developing a method to create LEDs on a thin disks of silicon coated in metal, making production a lot cheaper.

Gallium nitride is what causes light to be emitted in LEDs. While some of the light is projected up, some of it goes down and is lost. This accounts for part of the reason current LEDs are so costly- they require an additional reflector to bounce light back that would otherwise be lost.

The Purdue team managed to engineer an LED on a silicon layer, with a built-in metallic reflective layer, made of zirconium nitride. With these ingredients sprinkled onto the silicon, the disk is heated at extremely hot temperatures, causing a crystal structure to form that is key to functioning LEDs.
Read the rest of the post . . .

Tiniest Bolometer Ever

If you've never seen a bolometer before, its unlikely you will get a glimpse of the new nano-sized electronic detector created by a team of physicists at Rutgers University, NASA's Jet Propulsion Laboratory in Pasadena, and the State University of New York at Buffalo.

That's because the minuscule device is about 500 nanometers long and 100 nanometers wide; an astonishing 100 times smaller than the thickness of a strand of your hair.

Bolometers act as detectors of infrared waves by absorbing photons or packets of light, and measuring the heat generated. But the newly developed "hot-electron nanobolometer" is no mere imitator.

According to a lead scientist of the project, it is potentially 100 times more sensitive than current bolometers, and absorbs far-infrared light much faster. While it works by measuring heat, the circuit itself operates at extremely cold temperatures, around 459 degrees below zero Fahrenheit. Brrr!

Astronomers are no doubt grateful for the new technology, as it helps them inch closer towards the ability to see invisible light created during the inchoate days of the early universe. Both abundant and significant, invisible light comprises about 98% of the light emitted since the big bang 14 billion years ago.

Many believe that exploring invisible light may provide clues into star and galaxy formation. The scientists working on the nanobolometer predict that it be widely applied to future satellite-based far infrared telescopes in space.
Read the rest of the post . . .

Shortest Flash of Light Created

Scientists have created the shortest-ever flash of light, 80 attoseconds (one billionth of one billionth of a second) long. Up until now, the shortest light pulse is recorded at 130 attoseconds, set in 2007. These short flashes have huge implications; they might be able to let scientists view the movement of electrons around large atoms.

The flash was short enough to capture an image of a laser pulse previously too fast to be seen ( see photo on left). The method used to generate the flash is akin to a domino effect, initial pulses are fired into a cloud of neon gas, which in turn excite the neon atoms who release energy as super short flashes of light.

The flashes from the neon atoms were moved onto a second gas cloud so that the researchers could figure out exactly how short the light flashes were. Further analysis showed light flashing at 80 attoseconds. But scientists aren't done yet. The goal is to make light pulses as short as the time it takes for an electron to travel around a hydrogen atom, 24 attoseconds (considered to be the atomic unit of time).

Still not satisfied? The imaging of fundamental particles like protons, at zeptoseconds (trillionths of a billionth of a second) might even be possible someday.
Read the rest of the post . . .

Bending Starlight Solved by Non-Physicists

Two mathematicians fiddling around with an extension of the fundamental theorem of algebra had no idea of the significant implications their work held for gravitational lensing, a prediction of Einstein's general theory of relativity.

Turns out Dmitry Khavinson and Genevra Neumann proved physicist Sun Hong Rhie's theory on gravitational lensing. Gravitational lensing explains the deceptive behavior of light traveling at extremely far distances.

A gravitational lens forms when distant light from a particularly bright source, like a star, "bends" in both directions around a massive object. This cosmic optical illusion misleads the observer (usually here on earth), into thinking the light originates from 2 sources, when in fact there is only one. What looks like 2 different stars is actually the same star.

The light-tricks depend on where the massive object lies and how many massive objects there are. A star looks like a circle when the massive object is directly between the star and the observer. A multitude of objects means the observer will view what appears to be a multitude of stars.

Rhie had been trying to determine how many mirages of stars could be created by the bending of light. She calculated that four massive objects lead to 15 ostensible stars, coming up with the formula 5n-5 stars, where n is the number of massive objects. Unfortunately, being "pretty sure" of something doesn't cut it in science: she needed cold proof.

Over on the west coast, mathematican Jefferey Rabin stumbled across Rhie's work and took a stab at it. He spent months on the problem with little success. In a simple twist of fate, someone in Rabin's department had left an article on the printer. Passing by, Rabin read it and realized someone had solved the problem, but with purely mathematical aims; they were completely unaware of gravitational lensing.

That article was Khavinson and Neumann's, and their work with rational harmonic functions had unknowingly proved Rhie's assertion. Another example of how important the dissemination of scientific knowledge is! Accidental discoveries make for great stories.
Read the rest of the post . . .

Who Says Perfectionism is a Bad Quality?

Scientists have created the first metamaterial made solely of metallic elements, that is able to absorb all the light that hits it with perfection. Metamaterials are artificially constructed materials that have extraordinary properties and are revolutionizing physics, especially in the fields of optics and electromagnetism.

While natural materials use light in a limited number of ways, manmade metamaterials gain their unusual properties from their structure (rather than their composition) and can be developed to have properties beyond those of nature, allowing humans to control light in ways that were previously impossible. The metamaterial engineered by scientists from Duke University and Boston College has a particular geometric surface, which allows it to completely absorb microwaves.

Using computer simulations based on previous data, researchers created the metamaterial by designing resonators capable of individually joining to electric and magnetic components of an electromagnetic wave.

Ultimately, structure (how its molecules and atoms are arranged) alone allows the metamaterial to absorb all the light instead of reflecting or transmitting it. The actual material doesn't play a major role in how the metamaterial controls the light that it comes in contact with. However, because this metamaterial is composed of purely metallic elements, it is flexible enough to be highly favorable in applications related to light detection and collection.
Read the rest of the post . . .

Was Copernicus Wrong?

Admit it, sometimes you think the world revolves around you. In fact, it's possible that the whole universe revolves around you, and a new analysis may be able to confirm your ultra specialness once and for all. Don't go getting all full of yourself, until you read the post below by our newest Physics Buzz blogger, who we call Uncalm.
-Buzz

Polish astronomer Nicolaus Copernicus stated that the earth is not in a special, central place in the universe. As observers, humans on earth have no advantage over other places in the universe.

But was he wrong? Is the earth actually located in the center of a matter-free bubble, a billion light years long, and enclosed by a massive dense shell of material?

If so, dark energy, which is invisible (like dark matter) and thought by physicists to pervade all of space while causing the universe to expand faster, may not exist. The force of gravity would cause galaxies inside the bubble to speed towards the earth, creating the illusion that the universe’s expansion is accelerating. Your average observer wouldn’t be able to tell the difference.

Robert Caldwell of Dartmouth College and Albert Stebbins of the Fermi National Accelerator Laboratory believe that they can test whether the earth is in a special location of the universe.

If the earth was located in the center of an immense bubble, microwave background radiation (a form of light found throughout all of space and left over from the big bang) in the universe should contain small deviations from a perfect blackbody spectrum.

Aptly named, a perfect blackbody is an object that absorbs all the light that hits it (none is passed through or reflected), so it appears black when cold. The blackbody spectrum is the amount of light emitted from the blackbody (called blackbody radiation) at each wavelength. If the blackbody is at a hot temperature, it will emit exactly as much as it absorbs, at every wavelength.

So, the spectrum from microwave background radiation in the universe coming towards the earth centered in a bubble (sans reflection), would generate a curve similar to that of a perfect blackbody spectrum.

Unfortunately, NASA’s Cosmic Background Explorer sent out in 1990 did not have the ability to detect such small deviations. But the Absolute Spectrum Polarimeter (pictured), a new NASA satellite in the early stages of inception could detect these deviations.

According to NASA, the satellite could be launched in the next decade. Early polarimeters worked by using a Nicol prism to produce a beam of plane-polarized light, which is passed through a tube and analyzed. To improve accuracy, several other prisms are used to introduce rotation by a few degrees for half of the light, creating a split field.

Caldwell and Stebbins think that data from observations of microwave background radiation might shatter the illusion of dark energy, or confirm that the earth ain’t nothing special.

In any case, most people already think of themselves as the center of the universe.

Read the rest of the post . . .

PASER schmazer

You know what a laser is of course. The term stands for Light Amplification by Stimulated Emmission of Radiation. You may not know that they were based on principles developed with the maser (Microwave Amplification by Stimulated Emmission of Radiation), and have led to the saser(a sound laser). Now there's the paser, a particle version of the laser.

A paper in this week's Physical Review Letters describes the first paser. You can read more about it on the American Institute of Physics web page Physics News Update.
Read the rest of the post . . .