Faster than light travel

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Light travels at about 186282 miles per second (299792 kilometers per second), and according to the Standard Model, nothing can travel faster than the speed of light when it is traveling in a vacuum. Many people on Earth are interested in distant locations. Unfortunately, even the closest known extra-solar object is 4 light years away, and other more interesting objects are astronomically further away. Most of the known exoplanets are over 500 light years away, and the center of the Milky Way galaxy is about 26,000 light years away.

For various reasons, it would be convenient to send stuff to those locations in less than 500 years -- but that would require traveling faster than "c", the speed of light through the vacuum of space.

There are several effects that are informally described as going "faster than the speed of light". So far none of them have conclusively demonstrated moving an object or information faster than "c", the speed of light in a vacuum.

[edit] tachyons

[edit] quantum entanglement

aka "spooky action at a distance"

[edit] The Cerenkov Effect

The blue glow of underwater nuclear reactors is due to Cherenkov radiation, also spelled Cerenkov radiation. The refractive index of water is about 1.333 -- in other words, the speed of light through water is about 3/4 the speed of light in a vacuum. When electrons pass through water at a constant speed faster than the speed of light through that water, the water emits Cherenkov radiation. Because no Cherenkov radiation is observed when those electrons travel through air, we conclude that those electrons are traveling slower than the full speed of light in a vacuum. The blue photons themselves presumably travel at the same speed through the water as any other photon through that water, about 3/4 the speed of light in a vacuum.

[edit] Is this merely a misunderstanding of Cerenkov radiation, or is it some other effect entirely?

The Cerenkov Effect makes faster-than-light travel possible, but it has only been achieved by photons. The reason it is possible is because, as Einstein had predicted, faster-than-light travel in a vaccuum is a constant and requires infinite energy to attain. However, the Cerenkov effect occurs in a material setting in which matter reduces the speed of light, thus making it possible for sub-atomic particles to surpass the speed of light in the form of electromagnetic radiation (known as Cerenkov radiation), occurring when the charged particles (usually electrons) travel through a dielectric medium at a speed greater than that which light would travel through the same medium. However, this does not violate the absolute limit of a speed greater than that at which light travels in a vacuum.