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Wade Kennedy
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Wade Kennedy

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What does the front of a beam of light look like ? Or do we have to wait for a speed of light camera !
 
Sonic Rainboom

One of the basic laws of physics is that nothing can travel faster than light.  Actually that isn’t quite true.  Specifically, nothing can travel faster than light travels in a vacuum.  It is possible for things to break the light barrier when traveling through a material.  The effect is known as Cherenkov radiation.

While the speed of light in a vacuum is a universal constant, the speed of light in different materials can vary.  For example, when light travels through water, its speed is about 75% that of light in a vacuum (speed in this case meaning phase velocity for you optics fans).  It is this difference in speed that causes the refraction of light.  If you’ve ever seen a straw in a glass of water appear to be “broken”, then you’ve seen refraction in action.  The speed of light in a material also varies slightly by wavelength, which means different colors refract by slightly different amounts, leading to things like rainbows (but that’s a story for another time).

Because light is slowed when moving through a material, it is possible for particles to “break the light barrier” in those materials.  For example, in nuclear reactors, electrons are emitted with so much energy that they are travelling at nearly the speed of light (in a vacuum).  When those electrons travel through the water surrounding the reactor they are traveling faster than light travels through water, thus breaking the light barrier.

You’re probably familiar with the sonic boom that occurs when a plane breaks the sound barrier.  Actually, the entire time a plane flies faster than the speed of sound, it is followed by a sonic boom.  What happens is the plane is moving so fast that the sound pressure makes a cone of pressure (shock wave) that trails the plane.  The cone expands at the speed of sound, which we hear as a boom when it reaches us.  

A similar effect occurs when an electron breaks the light barrier in water (or other materials).  The electron causes an optical shock wave, and the result is a kind of sonic rainboom, known as Cherenkov radiation.  Most of the light emitted by the shock wave is ultraviolet, but it also emits blue and violet light, so Cherenkov radiation is typically a brilliant blue light.

A few days ago (http://goo.gl/TVJC7C) I talked about the IceCube neutrino observatory, and noted that they don’t detect neutrinos directly, but instead detect flashes of light that occur when a neutrino strikes a water molecule.  What I didn’t say is that the flash of light is due to  Cherenkov radiation.  The interstellar neutrinos have so much energy that when they strike an oxygen nucleus a muon (one of the electron’s heavier cousins) is emitted with a speed faster than light in water or ice.  The muon creates Cherenkov radiation which can be observed by the photodetectors, as seen in the figure below (http://goo.gl/rEbpQI).

Since the Cherenkov radiation is a directional cone, by timing the arrival of the flash at different detectors in the array we can determine not only the energy of the neutrino, but the direction of its origin.  This is how we can determine that they really are from interstellar space, and not due to something like cosmic rays hitting the atmosphere.
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Wade Kennedy

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Sam. Thank you !
 
“The pictures are there, and you just take them” – Robert Capa

Last night’s sunset at the J Street Marina in Chula Vista. Have a great weekend everybody! 

What are your weekend plans?

I appreciate your +1, Shares and Comments. Please Share this if you Like it because Sharing is Caring. Thanks!

www.SamAntonio.com

#Sunset   #fridayfun   #SanDiego   #Boats   #california   #cloudscape  
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That one really gets me !
 
"When you rise in the morning, give thanks for the light, for your life, for your strength. Give thanks for your food and for the joy of living. If you see no reason to give thanks, the fault lies in yourself."
— Tecumseh







#nature   #savethetrees   #gratitude   #morning  
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Muito bonito
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Who are you Zoraya
 
River Coupall in Scotland.

"Life is like the river, sometimes it sweeps you gently along and sometimes the rapids come out of nowhere."
— Emma Smith






#rivercoupall   #scotland   #river   #lifelessons  
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How is the recognition when everyone becomes different
 
"Be different so that people can see you clearly amongst the crowds."
— Mehmet Murat ildan







#peacock   #unique   #beyourself   #lifelessons  
Quote and photo composition ©ZorayaTonel. Reshare, don't download please.
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Waaaaarrrrrtttt
 
The Porpoise Galaxy from Hubble
Image Credit: +NASA, +European Space Agency, ESA, and The Hubble Heritage Team (STSci/AURA)
http://apod.nasa.gov/apod/ap130624.html

What's happening to this spiral galaxy? Just a few hundred million years ago, NGC 2936, the upper of the two large galaxies shown, was likely a normal spiral galaxy -- spinning, creating stars -- and minding its own business. But then it got too close to the massive elliptical galaxy NGC 2937 below and took a dive. Dubbed the Porpoise Galaxy for its iconic shape, NGC 2936 is not only being deflected but also being distorted by the close gravitational interaction. A burst of young blue stars forms the nose of the porpoise toward the left of the upper galaxy, while the center of the spiral appears as an eye. Alternatively, the galaxy pair, together known as Arp 142, look to some like a penguin protecting an egg. Either way, intricate dark dust lanes and bright blue star streams trail the troubled galaxy to the lower right. The above recently-released image showing Arp 142 in unprecedented detail was taken by the Hubble Space Telescope last year. Arp 142 lies about 300 million light years away toward the constellation, coincidently, of the Water Snake (Hydra). In a billion years or so the two galaxies will likely merge into one larger galaxy.
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Wade Kennedy

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Wow ! That just about takes all the cake. ... .
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Wow! ×10+?
 
Image of the Day via +The Scientist:
Neuronal Network - Fluorescent neurons in the peripheral nervous system of an embryonic mouse are shown in this awesome image.
Nikon Small World, Zhong Hua, Johns Hopkins University School of Medicine
http://bit.ly/1inWqc9
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Now yor tolkin
 
"Becoming fearless isn't the point. That's impossible. It's learning how to control your fear, and how to be free from it."
― Veronica Roth






#courage   #journey   #lifelessons   #road  
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Bonito
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Renewal in today from the distillation of yesterday
 
"Don't drag yesterday's problems into this brand new day. Give yourself and those around you a break, and start fresh."
— Author Unknown





#monday   #brandnewday   #sunrise   #mountainsunrise   #lifelessons  
Quote and photo composition ©ZorayaTonel. Reshare, don't download please.
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Wow. Way of Wonder
 
"People often say that 'beauty is in the eye of the beholder,' and I say that the most liberating thing about beauty is realizing that you are the beholder. This empowers us to find beauty in places where others have not dared to look, including inside ourselves."
— Salma Hayek







Image Copyright:  "Plitvice Winter", Croatia | Andreas Resch | http://500px.com/photo/27414251

#winter   #croatia   #plitvicelakes   #beauty   #lifequotes  
Quote and photo composition ©ZorayaTonel. Reshare, don't download please.
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Have him in circles
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Official Cali Prime's profile photo
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