Science and Exploration

[dreadgeek]

So, I said I'd do this a few days ago. I apologize for the delay:

Science advances not when someone exclaims "Eureka!" but when someone cocks their head and says, "well now, that's unexpected". There are a number of issues that caused astronomers, astrophysicists and cosmologists to say "well, I wasn't expecting that". I'll only take two because they are the easiest to explain and require no math to get to an understanding.

The first is the concept of gravity lensing. Gravity lensing is caused when the light of a very distant object is warped around an intervening mass like, say, a galaxy. As everyone knows, light moves from point A to point B and, as everyone is aware of from the idea of black holes, light can be affected by gravity. When this happens at astronomical distances what happens is that the object either appears as either a ring (known as an Einstein ring) or it'll appear slightly offset from where the object actually is. Now, if we know the approximate mass of a galaxy (which can be estimated from its size and density of stars) then we can know about how much refraction there should be. The problem then is that astronomers see more lensing than can strictly speaking inferred from the masses in between them and some distant light source. This begs the question of *why* this is happening.

The second concept is the spin of a galaxy. This is a bit more complicated. Think of a spiral galaxy like a solar system writ large. In the center of the galaxy is a hugely massive orbit (a supermassive black hole) and most of the mass of the galaxy is in that bulge in the center. Then there's the spiral arms. Calculating the rotational speed of a galaxy of a given size *should* be a pretty straightforward application of Newton's and Kepler's laws that work very well when applied to solar systems. The basic idea here is that the closer to the gravitational center an object is, the faster it rotates and the farther out it is, the slower it rotates. Except that's *not* what we see. Instead we see a near uniform rotational speed even at the outer extremities of the galaxy--for instance where our solar system is in relation to the rest of the Milky Way. Again, this begs the question of *why*.

Now, the proposed answer is that there is some 'missing' matter that we can't directly observe. This missing matter is called 'dark matter'. Why dark? Because it does not interact strongly with the electromagnetic force (light in all its form and splendor). Ordinary matter (the kind of stuff we and everything we can see) will interact with the electromagnetic force. For instance, someone walking into the room where you currently sit reading this can see you because all of the matter that makes you you is reflecting electromagnetism in the visible portion of the spectrum. Dark matter doesn't do that. Instead if it interacts with light at all it does so very weakly and all evidence, so far, is that it does not interact with it at all.

If this were all that there was to dark matter it would be almost impossible to find but fortunately this isn't the case. Dark matter *does* interact with itself and when it does it splits off into exotic particles that were predicted by physicists who started working on the problem. The experiment aboard the ISS (International Space Station) detected the kinds of particles that the theory predicted which is usually a sign that we're on the right track.

Dark matter and dark energy are *not* the same thing and shouldn't be confused with one another.

Cheers
Aj

[Corkey]

You're forgiven.
Understood that well, thank you.

[dreadgeek]

So since I mentioned dark energy I thought I would go ahead and talk about this subject as well. There's another problem in cosmology and it is this: the expansion of the Universe isn't slowing down. To understand why this is a problem it's necessary to go back to the very beginning: the Big Bang. So according to the prevailing model, at one point the whole of the Universe was contained in a space about the size of what is called the Planck length (10^-43 or 1 with 43 zeroes in front of it) which is the smallest anything existing can be said to be. For reasons that may forever be beyond our understanding this fantastically small object suddenly became *much* larger. This is the Big Bang. In the first few moments of the Universe spacetime grew hugely. Things settled down after a while, the balance of matter-antimatter tipped in favor of matter and it started to get cold enough for atoms to start to form. After the rapid inflation expansion started to slow down a bit and matter started clumping together to form stars and galaxies and all the rest of the things observable in the Universe.

Now, here's where things get interesting. Gravity is *always* attractive and is caused by the warping of spacetime by the presence of mass. The consequence of this is that what we should see is that over time, the expansion of the Universe should slow down and then, possibly, reverse coming together in a Big Crunch (or as Douglas Adams put it in Restaurant at the End of the Universe, a gnab gib). The problem is that we aren't observing this. In fact, not only has the expansion continued but it is still accelerating. This cries out for explanation.

That explanation is dark energy. *Some* form of energy, that we lack the means to detect at present levels of technology, is pushing the Universe apart. We don't know precisely what it is but there is a damn lot of the stuff whatever it is. This more or less seals the fate of the universe. Eventually what will happen is that all of the galaxies will be so far apart from one another that they will be too faint to see.

How do we know that the galaxies are all rushing away from one another? (on the whole, the Milky Way is going to eventually collide with the Andromeda galaxy because the greater mass of our galaxy is pulling the Andromeda galaxy toward us) We know because of what is called red shift. This is simply the familiar Doppler effect applied to light. When a siren is approaching you the pitch increases and as it speeds away from you the pitch decreases. The same thing happens to light (although we can't detect it because the distances light travels here on Earth can never be far enough to see any kind of shifting) but at the astronomical level stars or galaxies moving away from us have their light shifted toward the red part of the spectrum. The more red shift the farther away you are from the observed object.

Cheers
Aj

[Jean_TX]

Scientists are further investigating a phenomenon called 'dark lightning' : "Dark lightning that is almost invisible within clouds may regularly blast airline passengers with large numbers of gamma rays, scientists find." Although it sounds ominous, the effects on the body may not be dangerous. The full article can be read at http://www.livescience.com/28594-dar...assengers.html

[Corkey]

http://news.yahoo.com/ancient-creatu...183441713.html

Australopithecus sediba, human and apelike creature.

[KCBUTCH]

HAD TO SHARE LOVE THIS

[puddin']

http://www.npr.org/blogs/krulwich/20...towel-on-earth



(solly, don't know how to embed)

[Hollylane]

Earth's core far hotter than thought



New measurements suggest the Earth's inner core is far hotter than prior experiments suggested, putting it at 6,000C - as hot as the Sun's surface.

[Tommi]

Soft Drink Consumption Tied To Increased Type 2 Diabetes Risk. Bloomberg News (4/25, Torsoli) reports, “Just one soft drink consumed daily can raise the risk of diabetes by 22 percent,” according to a study published April 24 in Diabetologia. The study found that “a mere 12 ounces serving size of sugar-sweetened soft drink a day may increase the chance of developing type 2 diabetes, the most common form of the disease.”

Reuters (4/25, Kelland) reports that researchers analyzed data from some 350,000 individuals in the UK, Denmark, Spain, Sweden, Italy, the Netherlands, France, and Germany who had provided information on the amount of naturally and artificially sweetened soft drinks consumed on a daily basis.

MyHealthNewsDaily (4/25, Rettner) reports, “In the study, people who drank a 12-ounce sugar-sweetened soda daily were 18 percent more likely to develop type 2 diabetes over a 16-year period compared with those who did not consume soda.” In addition, “people who drank two sodas daily were 18 percent more likely to have a stroke than those who drank one; those who drank three sodas daily saw the same risk increase compared with those who drank two, and so on.” Notably, “the results held even after the researchers took into account risk factors for type 2 diabetes, such as age and physical activity levels, body mass index (BMI) and the total daily calorie intake.”

MedPage Today (4/25, Petrochko) points out, “Compared with those who consumed lower levels of sugary soft drinks, high-level consumers were more likely to be male, physically active, less educated, smokers, and have a higher waist circumference,” whereas “juice and nectar high consumers were mostly younger, female, physically active, former smokers, and better educated than those with lower juice and nectar consumption.” Even though “soft drink consumption was linked with diabetes incidence, there was no association between diabetes and consumption of juices and nectars.”

[Toughy]

4th-Grade 'Science Test' Goes Viral: Creationism Quiz Claims Dinosaurs Lived With People

The Huffington Post | By Meredith Bennett-Smith
Posted: 04/26/2013 1:48 pm EDT | Updated: 04/26/2013 4:38 pm EDT

Dinosaurs hung out with humans; God created dinosaurs on the sixth day; the "behemoth" described in the Bible's Book of Job actually refers to a brontosaurus. These are some of the unscientific beliefs behind what appears to be a fourth-grade science quiz posted recently online.

http://www.huffingtonpost.com/2013/0...tml?ref=topbar


no wonder idiots get elected to office.........

[Corkey]

http://news.yahoo.com/blogs/sideshow...201729650.html

Ancient Egyptian city revealed.

[Greyson]

The World's Leading Science Cities

Science and technology are key drivers of economic growth. But where are the world's leading science cities? A new study published in Nature's Scientific Reports ranks the top cities for physics research around the world.

Much has been made of declining U.S. economic and technological dominance and "the rise of the rest" of the world. Their findings indicate that the U.S. has lost substantial ground as the global center for physics. In the 1960s, the U.S. accounted for 85.6 percent of physics papers tracked by the authors; in the past decade, U.S. output has declined to 36.7 percent.

"Physics knowledge was highly localized in a few cities in the eastern and western coasts of the USA and in a few areas of Great Britain and Northern Europe," they write. "In 2009 the picture is completely different with many producer cities in central and southern parts of the USA, Europe and Japan."

The big takeaway: While science is becoming more distributed globally, its production at the highest level remains incredibly concentrated and spiky. Indeed, the world's leading centers of physics have remained essentially the same for the past three decades. While Chinese cities have risen as consumers of scientific knowledge (alongside their economic growth), it remains to be seen if they can become leading producers of it.


Read More:

http://www.theatlanticcities.com/job...-physics/5403/

[always2late]

http://bbc.in/1dKDTSd

[dreadgeek]

I know, it doesn't look scary. It's actually kind of beautiful which is why I'm using it as my current desktop background. But what *is* it? It's a map of orbits of every *known* Potentially Hazardous Asteroid (PHA). In other words, the map of every rock larger than 460 feet that has an orbit that passes uncomfortably close to the Earth. Close, because we're talking about space here, means within 5 million miles. To give you a sense of scale, the Moon is ~250,000 miles from the Earth. Five million seems like a lot of distance but when you consider that when it is at its closest, Venus is 38 million miles away. So we're talking very big numbers. The problem is that Earth has a serious gravitational pull and something within 5 million miles of the Earth is certainly going to be influenced by its gravity. How many objects are we talking about? Around 1,400! That's when it gets scary.

The reason why the size matters is that mass matters. Earth actually gets hit on occasion by fairly small pieces of rock but it's the large pieces that wreak havoc on the planet. That said, nothing in that graphic is in any real serious danger of hitting the planet in the next century. But longer out...? Something around 1,000 feet strikes the Earth approximately every 80,000 years. To give you sense of scale here, the asteroid that most likely blasted a chunk out of the Yucatan peninsula and likely delivered the coup de grace to the dinosaurs was somewhere in the range of 6 miles in diameter. Think Manhattan hitting the Earth.

Image page

Cheers
Aj

[Electrocell]

Brain-eating amoebas: What you need to know


Naegleria fowleri: A look at the brain-eating amoeba and how to avoid it.

Rex Features

A look at brain tissue infected with Naegleria fowleri.
MSN News 3 hr ago | By Heather Smith, MSN News of MSN News





Florida health officials have issued a warning for swimmers after a boy contracted Naegleria fowleri. Here's what you need to know about the deadly amoeba.






The Florida Department of Health has issued a warning for swimmers after a 12-year-old boy in the southwestern part of the state contracted a rare brain infection caused by Naegleria Fowleri (N. fowleri) while knee boarding with some friends in a water-filled ditch. Officials said that high water temperatures and low water levels combine to create the perfect breeding ground for N. fowleri, and warned the public "to be wary when swimming, jumping or diving in freshwater."

This latest case of infection comes less than a month after an Arkansas girl ended up in a hospital, fighting for her life. Here, we look at what it is and how to avoid the sometimes deadly brain-eating amoeba.

What is it?

N. fowleri is an amoeba that lives in warm freshwater, such as ponds, lakes and hot springs. It also thrives in the soil around it. Normally, it eats the bacteria found in these places, but when presented with the opportunity, it will eat brains. There is no evidence of this organism living in salt water. It is an amoeba belonging to the groups Percolozoa or Heterolobosea.

The amoeba invades the body and causes a rare brain infection known as primary amebic meningoencephalitis, or PAM, that eats away at brain tissue and is usually fatal, according to the Centers for Disease Control.

How do you get it?

N. fowleri invades the central nervous system through the nose. From there, the amoeba moves the along olfactory nerve fibers into the brain, where it uses its suckers to devour brain cells. It's difficult to treat because by the time it's been diagnosed, it's already caused significant damage.

N. fowleri is most often caught by people who have been swimming underwater, but it's also thought to be transmitted through inhaling infected dust. Last year, two people died in Louisiana after they used tap water to flush out their sinuses.

Where does it thrive?

Freshwater — especially warm freshwater. Most cases have occurred in Southern or Southwestern states, especially Texas and Florida. It's been known to show up in swimming pools and hot tubs that haven't been properly chlorinated. Last month, a popular water park in Arkansas voluntarily closed after a 12-year old girl who swam there was diagnosed with N. fowleri

How can you avoid them?

N. fowleri infections are very rare — they've only killed 128 Americans between 1962 and 2012, according to the Centers for Disease Control. But you can reduce your risk of catching it by keeping your head out of the water when you're swimming in water that hasn't been chlorinated. If you're flushing your sinuses, be sure to use distilled or recently boiled water.

How is it treated?

N. fowleri is treated with antifungals, antibiotics and steroids. The most recent survivor, a 12-year-old girl infected at an Arkansas water park, was also treated with an experimental breast cancer drug.

——

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[dreadgeek]

As Phil Plaitt points out in this article, every year around this time people start spreading this Internet meme that Mars will look as large as the Moon in the night sky. It's a hoax. It will always be a hoax because Mars *never* gets close enough to Earth to look as large as the Moon. At its closest pass Mars gets within 35 million miles of Earth. At its farthest point (where it is now) it is about 210 million miles from Earth (it's currently on the far side of the Sun from us). Mars is a relatively small planet. It is half the size of Earth. The moon is about half the size of Mars. The moon is just next door (250,000 miles) compared with with the 35 million miles between Earth and Mars at their closest. So in order for this meme to be true, an object only twice the size of our moon would have to appear to be the same size even though Mars is two and a half orders of magnitude farther away from Earth! That's not optically *possible*. With the naked eye Mars can only ever look like a tiny dot in the sky. If it ever *were* in an orbit that would make it look the same size as the Moon that would be a very interesting day on Earth (interesting, here, in the "Oh God, Oh God, we're all gonna die" sense).

So if you see a meme on Facebook telling you that if you go outside sometime in the next week it'll appear as if the planet has two moons, know that someone is pulling your leg because they are.

Cheers
Aj

[dreadgeek]

It was pointed out to me that 2.5 orders of magnitude might be a little difficult for people to grasp intuitively so to give you a sense of scale I'll use this. I live in Portland, OR but I work in Hillsboro, OR. That's about 20 miles one-way, door-to-door from home to office. One order of magnitude would be ten times that far or 200 miles. That would put me in Grants Pass, OR or just north of Seattle, WA. Two orders of magnitude would be 2000 miles away so that would be in the Detroit, MI region. Two and half orders of magnitude would be 3000 miles or somewhere in northern Maine.

So to understand the scale of distance between the Moon and Earth compared to Mars and Earth, do this; take a city that is around 25 miles from you. Find a city that is ten times that distance (one order of magnitude) away. Now, find a city that is 100 times further away (two orders of magnitude). Now find another city that is half-again as far away (two and half orders of magnitude) and THAT is the ratio of distance scaled down to terrestrial scales. . So, to scale, the Earth is as far away from Mars as Portland, OR is from northern Maine. The Earth is as far away from the Moon as Portland, OR is from Seattle WA.

Originally Posted by dreadgeek

As Phil Plaitt points out in this article, every year around this time people start spreading this Internet meme that Mars will look as large as the Moon in the night sky. It's a hoax. It will always be a hoax because Mars *never* gets close enough to Earth to look as large as the Moon. At its closest pass Mars gets within 35 million miles of Earth. At its farthest point (where it is now) it is about 210 million miles from Earth (it's currently on the far side of the Sun from us). Mars is a relatively small planet. It is half the size of Earth. The moon is about half the size of Mars. The moon is just next door (250,000 miles) compared with with the 35 million miles between Earth and Mars at their closest. So in order for this meme to be true, an object only twice the size of our moon would have to appear to be the same size even though Mars is two and a half orders of magnitude farther away from Earth! That's not optically *possible*. With the naked eye Mars can only ever look like a tiny dot in the sky. If it ever *were* in an orbit that would make it look the same size as the Moon that would be a very interesting day on Earth (interesting, here, in the "Oh God, Oh God, we're all gonna die" sense).

So if you see a meme on Facebook telling you that if you go outside sometime in the next week it'll appear as if the planet has two moons, know that someone is pulling your leg because they are.

Cheers
Aj

[Hollylane]

The Tamu massif is comparable in size to Olumpus Mons on Mars

Scientists say that they have discovered the single largest volcano in the world, a dead colossus deep beneath the Pacific waves.

A team writing in the journal Nature Geoscience says the 310,000 sq km (119,000 sq mi) Tamu Massif is comparable in size to Mars' vast Olympus Mons volcano - the largest in the Solar System.

The structure topples the previous largest on Earth, Mauna Loa in Hawaii.

The massif lies some 2km below the sea.

It is located on an underwater plateau known as the Shatsky Rise, about 1,600km east of Japan.

It was formed about 145 million years ago when massive lava flows erupted from the centre of the volcano to form a broad, shield-like feature.

The researchers doubted the submerged volcano's peak ever rose above sea level during its lifetime and say it is unlikely to erupt again.

"The bottom line is that we think that Tamu Massif was built in a short (geologically speaking) time of one to several million years and it has been extinct since," co-author William Sager, from the University of Houston, US, told the AFP news agency.

"One interesting angle is that there were lots of oceanic plateaus (that) erupted during the Cretaceous Period (145-65 million years ago) but we don't see them since. Scientists would like to know why."

Prof Sager began studying the structure two decades ago, but it had been unclear whether the massif was one single volcano or many - a kind that exists in dozens of locations around the planet.

While Olympus Mons on Mars has relatively shallow roots, the Tamu Massif extends some 30 km (18 miles) into the Earth's crust.

And other volcanic behemoths could be lurking among the dozen or so large oceanic plateaux around the world, he thought.

"We don't have the data to see inside them and know their structure, but it would not surprise me to find out that there are more like Tamu out there," said Dr Sager.

"Indeed, the biggest oceanic plateau is Ontong Java plateau, near the equator in the Pacific, east of the Solomons Islands. It is much bigger than Tamu -- it's the size of France."

The name Tamu comes from Texas A&M University, where Prof Sager previously taught before moving to the University of Houston.

[Hollylane]

A crater lake at the summit threatens to create dangerous mud flows in the event of an eruption

Scientists from the UK, US and North Korea have joined forces to monitor the volcano responsible for one of the largest eruptions in history.

The volcano straddles the border between North Korea and China, and has been largely dormant since erupting a little over a thousand years ago.

Despite being at the top of the list of big eruptions, Mount Paektu remains obscure and enigmatic.

Details of the collaborative effort have been outlined in Science journal.

The international group of geologists has begun working on the volcano following a spate of recent earthquake activity that could indicate it is waking from slumber.

Surprisingly, the volcano is relatively unknown in the West, not helped by the fact that it takes a confusing array of names. In China it is known variously as Tianchi or Changbaishan, but its Korean name is Baegdu-san or Mount Paektu, while the Japanese call it Hakuto-san.

Around two thirds of the volcano lies in North Korea, with the remainder is in Chinese territory, and an estimated 30,000 tourists visit its Chinese flank each day, around twice the number visiting Mount Fuji in Japan.

In 940 AD, the volcano exploded in a huge eruption, known as the "millennium eruption" that threw ash vast distances. Measurements of ash deposits from that eruption measured in Japan indicate that this was one of the two largest known volcanic eruptions on Earth since that period, matched only by the Tambora eruption in Indonesia, in 1815 AD.

Dr James Hammond from Imperial College London, and Prof Clive Oppenheimer from the University of Cambridge have begun a collaborative study with North Korean scientists, aiming to understand the structure of the subterranean magma chamber lying beneath the volcanic mountain.

Explaining the origins of the project, Dr Hammond told BBC News: "The whole region is quite worried about the volcano because it has shown signs of activity, so the North Koreans put a lot of effort into watching it, and basically said 'do you want to come to Korea, could you bring some equipment?'"

UK seismometers, deployed on the volcano's flanks, will reveal its structure and activity

The team has deployed a set of seismometers that can record earth tremors associated with the movement of magma beneath the volcano.

Organising a scientific collaboration in North Korea has not been without logistical and bureaucratic hurdles, but Dr Hammond continued: "What made it possible was having great people involved who were passionate about doing this, at all levels, from the scientists on the ground to those higher up where the decisions get made."

The study will help scientists understand why the volcano is there, which is something of a geological mystery, and why rock is melting at its heart, possibly stoking a future threat.

"This project is not about monitoring the volcano or predicting when the eruption will happen, but is about understanding what happened during the millennium eruption and also looking at what its state is now, using geophysical techniques. This will help us understand what is driving the volcano," Dr Hammond explained.

Prof James Gill, from University of California, Santa Cruz, has been working on the Chinese side of the volcano for some years, but is not involved in the new study. He told BBC News: "The volcano has erupted big time in the past, and were it to happen again, the Chinese, South Korean and Japanese economies could all be affected.

"There was a crisis in 2002-2005 when the seismicity picked up, the gas chemistry of the fumaroles changed, the volcano inflated, and it might have erupted. It may still be dangerous.

"The North Korean underground nuclear test site is only 70km or so away, so when the last test took place, the South Koreans were concerned that this might set off the volcano.

"One of the world's biggest volcanoes is sat in a backwater of the Cold War."

Prof Gill described some of the difficulties of carrying out field work at a militarised border, sampling rocks under armed escort. The new collaboration with the North Koreans is something of a landmark in current scientific co-operation with the isolated state.

This is not the only volcano that Prof Oppenheimer and Dr Hammond have worked on in difficult circumstances. They have previously studied volcanoes that straddle the border of Eritrea and Ethiopia. Like Mount Paektu, that investigation also ran into challenges due to the local political situation, but underlines the fact that natural hazards pay no attention to political differences.

[Smiling]

I am certainly not a scientist, but holy crap; I can see a lot of possibilities in this discovery! Absolutely incredible....


http://www.eurekalert.org/pub_releas...-sli092513.php

Seeing light in a new light

Scientists create never-before-seen form of matter

Harvard and MIT scientists are challenging the conventional wisdom about light, and they didn't need to go to a galaxy far, far away to do it.

Working with colleagues at the Harvard-MIT Center for Ultracold Atoms, a group led by Harvard Professor of Physics Mikhail Lukin and MIT Professor of Physics Vladan Vuletic have managed to coax photons into binding together to form molecules – a state of matter that, until recently, had been purely theoretical. The work is described in a September 25 paper in Nature.

The discovery, Lukin said, runs contrary to decades of accepted wisdom about the nature of light. Photons have long been described as massless particles which don't interact with each other – shine two laser beams at each other, he said, and they simply pass through one another.

"Photonic molecules," however, behave less like traditional lasers and more like something you might find in science fiction – the light saber.

"Most of the properties of light we know about originate from the fact that photons are massless, and that they do not interact with each other," Lukin said. "What we have done is create a special type of medium in which photons interact with each other so strongly that they begin to act as though they have mass, and they bind together to form molecules. This type of photonic bound state has been discussed theoretically for quite a while, but until now it hadn't been observed.

"It's not an in-apt analogy to compare this to light sabers," Lukin added. "When these photons interact with each other, they're pushing against and deflect each other. The physics of what's happening in these molecules is similar to what we see in the movies."

To get the normally-massless photons to bind to each other, Lukin and colleagues, including Harvard post-doctoral fellow Ofer Fisterberg, former Harvard doctoral student Alexey Gorshkov and MIT graduate students Thibault Peyronel and Qiu Liang couldn't rely on something like the Force – they instead turned to a set of more extreme conditions.

Researchers began by pumped rubidium atoms into a vacuum chamber, then used lasers to cool the cloud of atoms to just a few degrees above absolute zero. Using extremely weak laser pulses, they then fired single photons into the cloud of atoms.

As the photons enter the cloud of cold atoms, Lukin said, its energy excites atoms along its path, causing the photon to slow dramatically. As the photon moves through the cloud, that energy is handed off from atom to atom, and eventually exits the cloud with the photon.

"When the photon exits the medium, its identity is preserved," Lukin said. "It's the same effect we see with refraction of light in a water glass. The light enters the water, it hands off part of its energy to the medium, and inside it exists as light and matter coupled together, but when it exits, it's still light. The process that takes place is the same it's just a bit more extreme – the light is slowed considerably, and a lot more energy is given away than during refraction."

When Lukin and colleagues fired two photons into the cloud, they were surprised to see them exit together, as a single molecule.

The reason they form the never-before-seen molecules?

An effect called a Rydberg blockade, Lukin said, which states that when an atom is excited, nearby atoms cannot be excited to the same degree. In practice, the effect means that as two photons enter the atomic cloud, the first excites an atom, but must move forward before the second photon can excite nearby atoms.

The result, he said, is that the two photons push and pull each other through the cloud as their energy is handed off from one atom to the next.

"It's a photonic interaction that's mediated by the atomic interaction," Lukin said. "That makes these two photons behave like a molecule, and when they exit the medium they're much more likely to do so together than as single photons."

While the effect is unusual, it does have some practical applications as well.

"We do this for fun, and because we're pushing the frontiers of science," Lukin said. "But it feeds into the bigger picture of what we're doing because photons remain the best possible means to carry quantum information. The handicap, though, has been that photons don't interact with each other."

To build a quantum computer, he explained, researchers need to build a system that can preserve quantum information, and process it using quantum logic operations. The challenge, however, is that quantum logic requires interactions between individual quanta so that quantum systems can be switched to perform information processing.

"What we demonstrate with this process allows us to do that," Lukin said. "Before we make a useful, practical quantum switch or photonic logic gate we have to improve the performance, so it's still at the proof-of-concept level, but this is an important step. The physical principles we've established here are important."

The system could even be useful in classical computing, Lukin said, considering the power-dissipation challenges chip-makers now face. A number of companies – including IBM – have worked to develop systems that rely on optical routers that convert light signals into electrical signals, but those systems face their own hurdles.

Lukin also suggested that the system might one day even be used to create complex three-dimensional structures – such as crystals – wholly out of light.

"What it will be useful for we don't know yet, but it's a new state of matter, so we are hopeful that new applications may emerge as we continue to investigate these photonic molecules' properties," he said.