(Source: news.discovery.com)
10 Things You Didn’t Know About Light
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.
9) 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.”
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 thanGalileo, 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.
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, thatm=(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.
6)The light from the aurorae is the result of solar wind
When solar winds from cosmic events like solar flares reach Earth’s atmosphere, they interact with particles of oxygen atoms, causing them to emit stunning green lights. 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.
5) 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.
3) 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%.
2) 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.
1) 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.
(Source: io9.com)
6 Weird Facts About Gravity
Gravity: You don’t know what you’ve got ‘til it’s gone
Here on Earth, we take gravity so for granted that it took an apple falling from a tree to trigger Isaac Newton’s theory of gravitation. But gravity, which draws objects together in proportion to their mass, is about much more than fallen fruit. Read on for some of the strangest facts about this universal force.
1. It’s all in your head
Gravity may be pretty consistent on Earth, but our perception of it isn’t. According to research published in April 2011 in the journal PLoS ONE, people are better at judging how objects fall when they’re sitting upright versus lying on their sides.
The finding means that our perception of gravity may be less based on visual cues of gravity’s real direction and more rooted in the orientation of the body. The findings may lead to new strategies to help astronauts deal with microgravity in space.
2. Coming down to Earth is tough
Speaking of astronauts, their experience has shown that a switch to weightlessness and back can be tough on the body. In the absence of gravity, muscles atrophy and bones likewise lose bone mass. According to NASA, astronauts can lose 1 percent of their bone mass per month in space.
When astronauts come back to Earth, their bodies and minds need time to recover. Blood pressure, which has equalized throughout the body in space, has to return to an Earthly pattern in which the heart must work hard to keep the brain nourished with blood. Occasionally, astronauts struggle with that adjustment. In 2006, astronaut Heidemarie Stefanyshyn-Piper collapsed at a welcome-home ceremony the day after returning from a Space Shuttle mission to the International Space Station.
The mental readjustment can be just as tricky. In 1973, Skylab 2 astronaut Jack Lousma told Time magazine that he’d accidentally smashed a bottle of aftershave in his first days back from a month-long sojourn in space. He’d let go of the bottle in mid-air, forgetting that it would crash to the ground rather than just float there
3. For weight loss, try Pluto
Pluto may no longer be a planet, but it’s still a good bet for lightening up. A 150-pound (68 kilogram) person would weigh no more than 10 pounds (4.5 kg) on the dwarf planet. The planet with the most crushing gravity, on the other hand, is Jupiter, where the same person would weigh more than 354 pounds (160.5 kg).
The planet humans are most likely to visit, Mars, would also leave explorers feeling light-footed. Mars’ gravitational pull is only 38 percent that of Earth’s, meaning a 150-pound person would feel like they weigh about 57 pounds (26 kg).
4. Gravity is lumpy
Even on Earth, gravity isn’t entirely even. Because the globe isn’t a perfect sphere, its mass is distributed unevenly. And uneven mass means slightly uneven gravity.
One mysterious gravitational anomaly is in the Hudson Bay of Canada (shown above). This area has lower gravity than other regions, and a 2007 study finds that now-melted glaciers are to blame.
The ice that once cloaked the area during the last ice age has long since melted, but the Earth hasn’t entirely snapped back from the burden. Since gravity over an area is proportional to the mass atop that region, and the glacier’s imprint pushed aside some of the Earth’s mass, gravity is a bit less strong in the ice sheet’s imprint. The slight deformation of the crust explains 25 percent to 45 percent of the unusually low gravity; the rest may be explained by a downward drag caused the motion of magma in Earth’s mantle (the layer just beneath the crust), researchers reported in the journal Science.
5. Without gravity, some bugs get tougher
Bad news for space cadets: Some bacteria become nastier in space. A 2007 study published in the journal Proceedings of the National Academy of Sciences found that salmonella, the bacteria that commonly causes food poisoning, becomes three times more virulent in microgravity. Something about the lack of gravity changed the activity of at least 167 salmonella genes and 73 of its proteins. Mice fed the gravity-free salmonella got sick faster after consuming less of the bacteria.
In other words, Michael Crichton’s “The Andromeda Strain” had it wrong: The danger of infection in space may not come from space bugs. It’s more likely our own bugs grown stronger would strike us.
6. Black holes at the center of galaxies
Named because nothing, not even light, can escape their gravitational clutches, black holes are some of the most destructive objects in the universe. At the center of our galaxy is a massive black hole with the mass of 3 million suns. Scarier thought? It might be “just resting,” according Kyoto University scientist Tatsuya Inui.
The black hole isn’t really a danger to us Earthlings — it’s both far away and it’s remarkably calm. But sometimes it does put on a show: Inui and colleagues reported in 2008 that the black hole sent out a flare of energy 300 years ago. Another study, released in 2007, found that several thousand years ago, a galactic hiccup sent a small amount of matter the size of Mercury falling into the black hole, leading to another outburst.
The black hole, named Sagittarius A*, is dim compared with other black holes.
“This faintness implies that stars and gas rarely get close enough to the black hole to be in any danger,” Frederick Baganoff, a researcher at the Massachusetts Institute of Technology who was involved with the 2007 study, told LiveScience’s sister site SPACE.com. “The huge appetite is there, but it’s not being satisfied.”
What are quarks, and why do they have colors and flavors?
Quarks make up all matter, but have never been seen by themselves. And they have “flavors” and “colors” — though neither term has any relevance to what they actually do. Let’s take a look at why we need quarks to understand the world, and what their “colors” and “flavors” actually mean.
For many people, the question is, why do we need quarks at all? This pops up a lot, especially when people learn that quarks cannot be separated from each other and so we haven’t ever seen one on its own. Aren’t elementary particles like protons and neutrons enough? Why do we need to break them up further, to understand the universe?
![Atom Smasher Collides Particles at Record Energies
In the image: A simulation of a particle collision inside the Large Hadron Collider, the world’s largest particle accelerator near Geneva, Switzerland. When two protons collide inside the machine, they create an energetic explosion that gives rise to new and exotic particles.CREDIT: CERN
Physicists have started running the world’s largest particle accelerator at a new record energy and taking the first data from these ultra-powerful collisions.
Protons zoom around the 17 mile (27 kilometer) underground loop of the Large Hadron Collider below Switzerland and France, and then crash into each other, dissolving into new and sometimes exotic particles. Scientists have now sped up those protons a bit more, sending them speeding toward each other at energies of 4 teraelectron volts (TeV), creating a collision energy of 8 TeV — a new world record.
“The increase in energy is all about maximizing the discovery potential of the LHC,” Sergio Bertolucci, director of research at the LHC’s home lab CERN, said in a statement. “And in that respect, 2012 looks set to be a vintage year for particle physics.”
Ramping up to higher energies means the LHC has a better chance of creating the rare and highlysought particles it was designed to search for. These include the long-theorized, but not-yet-detected Higgs boson particle, as well as the particles predicted by a physics theory called supersymmetry. If supersymmetric particles are discovered, they may offer an explanation for the mystery of dark matter, the invisible stuff thought to make up most of the matter in the universe. [Wacky Physics: The Coolest Little Particles in Nature]
LHC was opened in September 2008, but shut off nine days later after an accident damaged a number of its superconducting magnets. The accelerator was fixed and got back up and running a little over a year later, and has been operating steadily since. Starting in March 2010, the proton beams have been colliding at energies of 3.5 TeV, creating a smash of 7 TeV.
“The experience of two good years of running at 3.5 TeV per beam gave us the confidence to increase the energy for this year without any significant risk to the machine,” said Steve Myers, CERN’s director for accelerators and technology. “Now it’s over to the experiments to make the best of the increased discovery potential we’re delivering them!”
The increased energy should mean more Higgs boson particles are produced, if they exist. Already, scientists at two of the LHC’s experiments, Atlas and CMS, have seen promising indications of an excess of particles weighing around 125 GeV (gigaelectron volts) — potentially a sign of the Higgs. Yet physicists say they don’t have enough data to confirm a discovery with certainty.
The increased energy should up the chances of creating Higgs particles inside the machine, though it will also create more of the “background” particles that produce similar signatures, and must be weeded out from the data.
Ultimately, scientists plan to run particle beams through the LHC at an astounding 7TeVeach, producing collisions of a whopping 14TeV. To do that, they’ll need to refurbish the accelerator during a planned shutdown at the end of this year.](http://25.media.tumblr.com/tumblr_m27hhpXcxP1qbkzabo1_500.jpg)
Atom Smasher Collides Particles at Record Energies
In the image: A simulation of a particle collision inside the Large Hadron Collider, the world’s largest particle accelerator near Geneva, Switzerland. When two protons collide inside the machine, they create an energetic explosion that gives rise to new and exotic particles.
CREDIT: CERN
Physicists have started running the world’s largest particle accelerator at a new record energy and taking the first data from these ultra-powerful collisions.
Protons zoom around the 17 mile (27 kilometer) underground loop of the Large Hadron Collider below Switzerland and France, and then crash into each other, dissolving into new and sometimes exotic particles. Scientists have now sped up those protons a bit more, sending them speeding toward each other at energies of 4 teraelectron volts (TeV), creating a collision energy of 8 TeV — a new world record.
“The increase in energy is all about maximizing the discovery potential of the LHC,” Sergio Bertolucci, director of research at the LHC’s home lab CERN, said in a statement. “And in that respect, 2012 looks set to be a vintage year for particle physics.”
Ramping up to higher energies means the LHC has a better chance of creating the rare and highlysought particles it was designed to search for. These include the long-theorized, but not-yet-detected Higgs boson particle, as well as the particles predicted by a physics theory called supersymmetry. If supersymmetric particles are discovered, they may offer an explanation for the mystery of dark matter, the invisible stuff thought to make up most of the matter in the universe. [Wacky Physics: The Coolest Little Particles in Nature]
LHC was opened in September 2008, but shut off nine days later after an accident damaged a number of its superconducting magnets. The accelerator was fixed and got back up and running a little over a year later, and has been operating steadily since. Starting in March 2010, the proton beams have been colliding at energies of 3.5 TeV, creating a smash of 7 TeV.
“The experience of two good years of running at 3.5 TeV per beam gave us the confidence to increase the energy for this year without any significant risk to the machine,” said Steve Myers, CERN’s director for accelerators and technology. “Now it’s over to the experiments to make the best of the increased discovery potential we’re delivering them!”
The increased energy should mean more Higgs boson particles are produced, if they exist. Already, scientists at two of the LHC’s experiments, Atlas and CMS, have seen promising indications of an excess of particles weighing around 125 GeV (gigaelectron volts) — potentially a sign of the Higgs. Yet physicists say they don’t have enough data to confirm a discovery with certainty.
The increased energy should up the chances of creating Higgs particles inside the machine, though it will also create more of the “background” particles that produce similar signatures, and must be weeded out from the data.
Ultimately, scientists plan to run particle beams through the LHC at an astounding 7TeVeach, producing collisions of a whopping 14TeV. To do that, they’ll need to refurbish the accelerator during a planned shutdown at the end of this year.
The most sensitive weight scale ever can weigh individual protons
A new subatomic weight scale can measure masses as tiny as one yoctogram. Less than the mass of a proton, a yoctogram is equivalent to a billionth of a billionth of a millionth of a gram.
A yoctogram is so tiny that it’s effectively the endpoint of the metric system - there aren’t any prefixes to describe units smaller than it. Until now, the most sensitive scales could only determine an object’s mass to within 100 yoctograms. Admittedly, while 100 yoctograms is a perfectly decent margin of error for, well, everything we encounter in the world around us, at the atomic scale it’s a bit like giving your weight to within the nearest ten tons.
All these ultra-tiny scales rely on nanotubes, which will vibrate at a specific frequency depending on the mass of the particles resting on them. As New Scientist reports, improving these nanotubes in turn allowed for the creation of even more sensitive scales:
To go even lower, Adrian Bachtold and his colleagues at the Catalan Institute of Nanotechnology in Barcelona, Spain, used short nanotubes. They give the best resolution and work at the low temperatures thought best for measuring frequency. Although the equipment was placed in a vacuum to minimise interference from other atoms, Bachtold removed any stray atoms by temporarily turning up the heat on the tubes to disrupt any bonds to atoms. Then the sensor was able to weigh an atom of xenon to the nearest yoctogram, or 10-24 grams. This makes it the first scale capable of detecting a single proton, which weighs in at 1.7 yoctograms.
Much as it might be fun to weigh oneself to the nearest proton, Bachtold says the main use of these scales will be in distinguishing nearly identical elements in chemical samples. There are also some potential medical applications, as certain molecular disease markers are only distinguishable at the proton scale.
Nature Nanotechnology via New Scientist. Image by Anteromite, via Shutterstock.
Mimicking butterfly wings could boost hydrogen fuel production
Chinese researchers have turned to the light absorbing properties of butterfly wings to significantly increase the efficiency of solar hydrogen cells, using biomimetics to copy the nanostructure that allows for incredible light and heat absorption.
Incredible Optics Photos
1. Lunar Halo
The beautiful circle surrounding the moon in this image is caused by ice crystals suspended in the air. Known as a paraselenic circle, this rare phenomenon comes from moonlight reflecting in complex ways off the crystals. While the circle is commonly only seen in sections, in some cases, such as this one, it can stretch around the entire sky.
A similar effect can occur on a chilly day with sunlight, forming a giant parhelic circle in the sky.
Image: Adam Kraft
2. Lightning Spectra
In his celebrated 1704 book Opticks, Isaac Newton describes shining a white light through a prism. When the light emerged, the famous physicist was surprised to see it broken into a dazzling rainbow of colors.
While this and other discoveries from Newton helped revolutionize the field of optics, it wasn’t until the 1800s that scientists understood how much information those rainbows contained. When passed through a prism, the light coming from a hot gas reveals its constituent elements in telltale lines of color.
In this image, taken during a thunderstorm over Paris, the forking lightning bolt heats surrounding air to between 36,000 and 54,000 degrees Fahrenheit, breaking apart air molecules into ionized plasma. The bright lines of the spectra reveals the presence of nitrogen and hydrogen in our atmosphere.
Image: Denis Joye
(Source: Wired)
How Einstein Came Up With Special Relativity
Time dilation. Length contraction. The fact that time moves faster at your face than it does at your feet. These are all experimentally verified consequences of the Special Theory of Relativity, proposed in 1905 by Albert Einstein. But the theory also helped explain one of the most nagging questions of modern physics, namely: how anything other than light can move. Minutephysics’ Henry Reich explains, with the help of some sliding switcheroos. [Via Henry Reich]
