Cherenkov
Radiation: When things go faster than light
Texto de terceiro.
Fonte: http://www.mostlyodd.com/cherenkov-radiation-when-things-go-faster-than-light/
Reator Nuclear IPEN do tipo MTR. |
Light
always slows down when it passes through matter, and when objects overtake it
we get Cherenkov radiation. It is a visual sonic boom, and it works in the same
way. Sonic booms are the result of reaching the speed of sound; sound ahead of
the object can’t dissipate or get away, so pressure builds. When the speed is
exceeded the pressure is released as a terribly loud shock wave that bludgeons
the ears of anything within a few kilometres. Cherenkov radiation is similar,
but quieter. To observe it, you will need a nuclear reactor core and a lot of
water.
In
certain nuclear reactor cores water is used as a coolant. Due to the fact that
water is, to be simple, made of stuff, it slows the speed of light that passes
through it to a rather zippy 224,910 km/s. This is quick, but less than the
ultimate limit, so it can be beaten.
The
reactor core releases charged electrons which disrupt the electromagnetic field
in the water, a field that includes light. They race at various speeds, but
many travel faster than light. The electromagnetic charge in front, which is limited
by the speed of light in the water, cannot escape. The waves propagate in front
and then the science happens. A photonic shock wave. Light is released.
If
we managed this feat with an electrically charged jet fighter the result would
be even more blindingly brilliant than a sonic boom, unfortunately it is
woefully impractical. Similarly if I were to accelerate a bowl of petunias
beyond the speed of sound, you would be able to hear it, but it would be much
less impressive. So, the result of Cherenkov radiation is nothing but a
pleasing, if rather unsettling blue glow from the water.
The
discovery of Cherenkov Radiation won Pavel Alekseyevich Cherenkov the Nobel
Prize in 1958, it shows that light slows down when it interacts. There
are many speeds of light, but in space, at 300,000km/s light is unbeatable,
that we know. Unless of course we
don’t understand the Universe at all. However the chances of that are rather
slim.
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