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Fed Up With Sluggish Neutrinos, Scientists Force Light To Move Faster Than Its Own Speed Limit


By Rebecca Boyle Posted 05.03.2012 at 3:07 pm

 

Our nation’s official keepers of time and other standards are breaking one of the cardinal rules: They have figured out how to make superluminal light pulses. This paradoxical sentence — faster-than-light light — is from a new paper explaining how to make the sine wave of light hunch in on itself and arrive a few nanoseconds earlier than it would if it had moved at light speed.

10 Things You Didn’t Know About Light


A week ago, who among us would have guessed that light, the universe’s ultimate speed demon, would be observed getting outpaced by a bunch of reckless neutrinos? Yes, these observations will obviously need to be checked and rechecked, but it just goes to show that you rarely know as much about something as you think you do.

So in the interest of keeping you all as educated on light as possible, here are ten little-known historical and scientific facts about everyone’s favorite source of illumination.

10) Light can make some people sneeze
Between 18% and 35% of the human population is estimated to be affected by a so-called “photic sneeze reflex,” a heritable condition that results in sneezing when the person is exposed to bright light.

The exact cause of the reflex is poorly understood, but people have been kicking around possible explanations for millennia; Aristotle, for example, chalked the reflex up to the heat of the sun on one’s nose, while most modern-day scientists posit that a cranial nerve responsible for facial sensation and motor control (that is in close proximity to the optic nerve) picks up on electrical signals intended for the optic nerve and tells the brain that there is an irritant in the nose that needs to be cleared out.

10 Things You Didn't Know About Light9) Plato thought that human vision was dependent upon light, but not in the way you’re imagining
In the 4th Century BC, Plato conceived of a so-called “extramission theory” of sight, wherein visual perception depends on light that emanates from the eyes and “seizes objects with its rays.”

Plato’s student, Aristotle, was among the first to reject the extramission theory and the idea of a so-called “active eye,” advocating instead a passive, “intromission” theory of vision, whereby the eyes receive information via rays of light as opposed to generating these rays on their own. (Image via.)

8) Einstein was not the first one to come up with a theory of relativity
Many people associate “the speed of light” with Einstein’s theory of relativity, but the concept of relativity did not originate with Einstein. Props for relativity actually go to none other than Galileo, who was the first to propose formally that you cannot tell if a room is at rest, or moving at a constant speed in one direction, by simply observing the motion of objects in the room.

What Einstein did do was bring Galileo’s conception of relativity up to speed by combining it with Newton’s work with gravity, and James Clerk Maxwell’s equations addressing electricity and magnetism (equations, it bears mentioning, that predicted that waves of electromagnetic fields move at 299 792 458 meters per second — i.e. the speed of light).

7) E=mc^2 was once m=(4/3)E/c^2
Einstein was not the first person to relate energy with mass. Between 1881 and 1905, several scientists — most notably phycisist J.J. Thomson and Friedrich Hasenohrl — derived numerous equations relating the apparent mass of radiation with its energy, concluding, for example, that m=(4/3)E/c^2. What Einstein did was recognize the equivalence of mass and energy, along with the importance of that relevance in light of relativity, which gave rise to the famous equation we all recognized today.

 

 

 

10 Things You Didn't Know About Light 6)The light from the aurorae is the result of solar wind
When solar winds from cosmic events like solar flaresreach Earth’s atmosphere, they interact with particles of oxygen atoms, causing them to emit stunning green lights like the ones captured by the International Space Station last week (featured here).

 

These waves of light — termed the aurora borealis and aurora australis (or northern lights and southern lights, respectively) — are typically green, but hues of blue and red can be emitted from atmospheric nitrogen atoms, as well.

 

10 Things You Didn't Know About Light5) Neutrinos aren’t the first things to apparently outpace the speed of light
The Hubble telescope has detected the existence of countless galaxies receding from our point in space at speeds in excess of the speed of light. However, this still does not violate Einstein’s theories on relativity because it is space — not the galaxies themselves — that is expanding away (a symptom of the Big Bang), and “carrying” the aforementioned galaxies along with it.

4) This expansion means there are some galaxies whose light we’ll never see
As far as we can tell, the Universe is expanding at an accelerating rate. On account of this, there are some who predict that many of the Universe’s galaxies will eventually be carried along by expanding space at a rate that will prevent their light from reaching us at any time in the infinite future.

10 Things You Didn't Know About Light3) Bioluminescence lights the ocean deep
More than half of the visible light spectrum is absorbed within three feet of the ocean’s surface; at a depth of 10 meters, less than 20% of the light that entered at the surface is still visible; by 100 meters, this percentage drops to 0.5%.

In fact, at depths of over 1000 meters — a region of the ocean dubbed the “aphotic zone” — there is no detectable light whatsoever. As a result, the largest source of light in the Earth’s oceans actually emanates from animals residing in its depths; marine biologists estimate that between 80 and 90 percent of deep-sea creatures are bioluminescent (image via).

 

10 Things You Didn't Know About Light2) Bioluminescence: also in humans!
Bioluminescene isn’t just for jellyfish and the notorious, nightmare-inducing Anglerfish; in fact, humans emit light, too.

All living creatures produce some amount of light as a result of metabolic biochemical reactions, even if this light is not readily visible. Back in 2009, a team of Japanese researchers reported that “the human body literally glimmers,” after using incredibly sensitive cameras (the light is a thousand times weaker than the human eye can perceive) to capture the first evidence of human bioluminescence, pictured here. It’s worth mentioning that images C, D, E, F, and G, are not thermal images, but actually pictures of emitted photon intensity over the course of an average day.

This time-dependent photon emission is illustrated in the chart shown in figure H. Figure I shows the thermal image you’re more accustomed to seeing.

 

10 Things You Didn't Know About Light1) It’s possible to trick your brain into seeing imaginary (and “impossible”) colors
Your brain uses what are known as “opponent channels” to receive and process light. On one hand, these opponent channels allow you to process visual information more efficiently (more on this here), but they also prevent you from seeing, for example, an object that is simultaneously emitting wavelengths that could be interpreted as blue and yellow — even if such a simultaneous, “impossible” color could potentially exist.

In theory, you can train yourself to see these and other so-called “imaginary” colors with a few simple tricks, which you can check out in our quick, how-to guide on seeing impossible and imaginary colors.

Republished from http://io9.com

http://gizmodo.com/5843897/10-things-you-didnt-know-about-light?tag=optics

Neutrino Beam Carries Message Through 240 Meters Of Solid Rock


The particle accelerator at Fermilab in Illinois was used to produce a neutrino beam with an encoded word to an underground detector 1 kilometer away

One of the earliest demonstrations of the Samuel Morse’s telegraph was used to bring updates of the Democratic National Convention in Baltimore to lawmakers in Washington D.C. The year was 1884, and newspapers all over the world were stunned at this new way to instantaneously transmit information over long distances. Paris’ Galignani’s Messenger remarked, “This is indeed the annihilation of space.” Now scientists have tested a new type of communication that conquers matter. Scientists have beamed a message carried by neutrinos, particles so small they pass through solid rock, to an underground detector about a kilometer away. Neutrinos could one day be used to communicate to submarines at depths that radio waves can’t penetrate, or even send messages right through the Earth’s core.

Neutrinos are naturally-occurring particles created through radioactive decay. They are really, really small. In fact, until recently they were thought to have no mass at all. But they do, somewhere between a ten-millionth and a millionth the mass of an electron. And unlike protons and electrons, neutrinos don’t have a charge. Their electrical neutrality allows them to pass vast distances through matter without being affected by it. The Earth is continually awash with neutrinos thrown off by the sun – each second about 65 billion solar neutrinos pass through every square centimeter of the Earth.

The scientists created the neutrino beam at the Fermilab Tevatron particle accelerator in Batavia, Illinois. Smashing protons against a target, in this case a wall of carbon, the protons break down into short-lived particles such as kaons and pions, which then break down further into muons, which break down into neutrinos. A steady flow of (extremely) accelerated muons produces a beam of neutrinos. Detecting neutrinos works the opposite way. When they interact with matter they emit easily detectable muons.

The so-called NuMI (Neutrinos at the Main Injector) beam was aimed at a detector behind 240 meters of solid rock. But for the same reason they can pass through matter, neutrinos are difficult to detect. To maximize the chance of a neutrino interaction the detector in the cave was stacked with dense materials including carbon, lead and iron. Even so, only about one out of every 10 billion neutrinos passing through the detector caused a detectable event, according to Dan Stancil, head of Electrical and Computer Engineering at North Carolina State University and the study’s lead author.

Schematic of the particle accelerator and the detector, known as Minerva.

To encode a message, the beam was turned on and off to represent the binary “1” and “0,” respectively. Trillions of neutrinos were sent with each pulse so that detection was guaranteed. In this way they encoded the word “neutrino.”

So will those areas in the office with bad cell phone reception be a thing of the past? Probably not for a while, but possibility for the neutrino beam would be to send communications to submarines deep beneath the ocean surface. Radio transmissions don’t travel well through water so fast communication with submarines is only possible near the surface, exactly where submarines don’t want to be during covert operations. The subs can still receive messages down in the deep but the extreme low frequency waves necessary to penetrate the water transmits at a clunky 1 bit per minute. In 2009 Virginia Tech physicist Paul Huber suggested that neutrino beams could transmit data to subs at about 100 bits per second. However, the formidable technology needed to produce the beams means communication would only be one way. And then there’s the problem of turning a sub into a neutrino detector. Huber proposes that it might be possible to coat the sub’s hull with a thin muon detector. He also mentions that the light caused by muons moving through the seawater could be used as a signal. Either way, we’re probably stuck with radio transmissions for a while yet.

In addition to deep sea communications, neutrinos could potentially be used to transmit messages straight through the Earth’s core to the other side of the planet. It could also solve a limitation we saw with the moon missions. Whenever the command module went around the far side of the moon it experienced a communication blackout. In the future, human and robotic missions to space needn’t worry if they’re receiving signals from a neutrino transmitter.

Neutrinos caused a stir in the quantum mechanics field last year when they were alleged to have broken Einstein’s speed limit to travel faster than light. Turns out to have been a break with careful experimentation instead. The current demonstration, with a message Morse code-like in its simplicity, could one day prove to be just as revolutionary.

 

http://singularityhub.com/2012/03/26/neutrino-beam-carries-message-through-240-meters-of-solid-rock/