Difference between revisions 5701327 and 5701329 on simplewiki

The idea of the heat death of the universe, proposed in 1851 by [[w:William Thomson, 1st Baron Kelvin|William Thomson]], stems from the [[second law of thermodynamics]], which states that [[heat]] tends to pass from hotter to colder bodies and eventually becomes uniformly distributed. As an elementary particle of matter (such as a proton) self‑gravitationally shrinks, its heat becomes intensified ("augmented") to a higher temperature and then radiated away into the ambient vacuum:
<blockquote>
Although mechanical energy is indestructible, there is a universal tendency to its dissipation, which produces throughout the system a gradual '''augmentation''' and diffusion of heat, cessation of motion and exhaustion of the potential energy of the material Universe.
:—Thomson, William. [http://zapatopi.net/kelvin/papers/on_the_age_of_the_suns_heat.html On the Age of the Sun’s Heat] ''Macmillan's Magazine'', 5&nbsp;March 1862, pp. 388–93
</blockquote>

==Mechanism of heat death==
Initially, the universe has the maximal (''i.e.'', zero) [[potential energy]], and the minimal (''i.e.'', zero) actual energy. Such a universe is in a state of '''heat death''' and exists as a uniform blanket of zero-temperature heat. According to the [[second law of thermodynamics]], heat tends to pass from hotter to colder bodies. So, when a portion of the zero&#8209;temperature heat self&#8209;gravitationally shrinks to a nonzero temperature, a half of the resultant nonzero&#8209;temperature heat becomes radiated into (contracted; show full)In 1974, [[Stephen Hawking]] applied the above&#8209;described principle of heat death to black holes and found that they, too, radiate away their energy ([[Hawking radiation]]) and consequently shrink in size; the smaller a black hole becomes, the faster it radiates away its remaining energy.

==References==
{{Reflist}}

[[Category:Cosmology]]
[[Category:Thermodynamics]]
[[Category:Universe]]