Cesium-137 or Caesium-137, represented as Cs-137 or 137Cs, is a radioactive isotope of cesium. In Dark, it is the main byproduct of a 1986 accident at the Winden Nuclear Power Plant, as well as the fuel used to power the time travel apparatus.

Use[edit | edit source]

In real life, Ceseium-137 has a number of commercial uses, including roles in radiation therapy, various types of radiation and moisture gauges, and radiometric dating.

In Dark, The Stranger inserts a glass vial of it into the apparatus to power it. H.G. Tannhaus theorizes that the device generates a Higgs field which increases the mass of the cesium. An electromagnetic pulse then causes it to implode into a black hole. They realize that the same thing must have occurred in the 1986 incident at the power plant.[1] As part of the coverup, Bernd Doppler stored this surplus Cs-137 in yellow barrels hidden in a cave below the plant, and sometimes moved onto a truck.

The Stranger filled up his vial from the truck. Later, Jonas Kahnwald and Claudia Tiedemann obtain more of it from the secret cave.

Chemical[edit | edit source]

Elemental cesium, assigned the atomic number 55, is a soft, shiny, silvery-golden alkali metal. As such, it has properties similar to sodium and potassium, including being highly reactive with water; as such, it must be stored in oil. It has a low melting point of only 28.5°C (83.3°F).

Cesium features prominently in two arenas at the center of Dark: timekeeping and atomic fission. The very definition of the second is based on the transition of the cesium-133 atom, and world time and frequency standards are set by atomic clocks which use cesium-133.

Cesium-137, specifically, is one of the two main "medium-lived" byproducts of uranium 235 and plutonium-239 fission (along with strontium-90). It can be highly dangerous because it is produced in large quantities, has a half-life of about 30.17 years, and reacts readily with water, making it easy to absorb into soft tissue.

References[edit | edit source]

  1. Dark Season 1 Episode 10: "Alpha and Omega"
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