quantumaniac:

Cherenkov Radiation
Don’t diss my bro Einstein quite yet - nothing can surpass the speed of light in a vacuum, 300,000 km a second. However, light obviously does not always travel through a vacuum, and its speed varies depending on the medium through which it travels. For example, photons travel about 25 percent slower in water than in a vacuum. Fun fact: the slowest light has ever been recorded is about 17 meters per second. (Technically light has been brought to a complete stop, but this isn’t technically ‘moving.’) 
In certain mediums, different objects can travel faster than light, including particles in a nuclear reactor. When particles travel faster than light in a certain medium, a blue glow arises - known as Cherenkov radiation. This can be thought of as the light equivalent of a sonic boom. 
In order for Cherenkov radiation to be emitted, the particles passing through the medium traveling faster than light must be charged - because these charged particles polarize the molecules of the medium; water molecules, for example. Although first predicted by English polymath Oliver Heaviside around 1888, the effect is named after Russian physicist  Pavel Alekseyevich Cherenkov, the 1958 Nobel Prize winner who was the first to study it thoroughly. 

quantumaniac:

Cherenkov Radiation

Don’t diss my bro Einstein quite yet - nothing can surpass the speed of light in a vacuum, 300,000 km a second. However, light obviously does not always travel through a vacuum, and its speed varies depending on the medium through which it travels. For example, photons travel about 25 percent slower in water than in a vacuum. Fun fact: the slowest light has ever been recorded is about 17 meters per second. (Technically light has been brought to a complete stop, but this isn’t technically ‘moving.’) 

In certain mediums, different objects can travel faster than light, including particles in a nuclear reactor. When particles travel faster than light in a certain medium, a blue glow arises - known as Cherenkov radiation. This can be thought of as the light equivalent of a sonic boom. 

In order for Cherenkov radiation to be emitted, the particles passing through the medium traveling faster than light must be charged - because these charged particles polarize the molecules of the medium; water molecules, for example. Although first predicted by English polymath Oliver Heaviside around 1888, the effect is named after Russian physicist  Pavel Alekseyevich Cherenkov, the 1958 Nobel Prize winner who was the first to study it thoroughly. 

(via manga9f5)

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