3 ms·
" To record a single bit by changing the state of a system requires an amount of energy no less than kT, where T is the absolute temperature of the system and k
by Tichy 14y ago
" To record a single bit by changing the state of a system requires an amount of energy no less than kT, where T is the absolute temperature of the system and k is the Boltzman constant."
How does that work? It seems odd that is is independent of the size of the system.
- marcosdumay 14y agoThat comes from the second law of thermodynamics. Setting a bit on the computer reduces its entropy, so it must dissipate enough heat to increase the entropy of the Universe by at least the same amount. Notice that this only applies to setting it into a known value. In theory there are some operations that we can do without dissipating any heat.
- Tichy 14y agoBut how do they know how much energy a bit requires?
- jessaustin 14y agoThat is technology-dependent. Mercury-filled-cylinder delay lines took more energy than modern DRAM.
- marcosdumay 14y agoAs I said, that's by the second law of thermodynamics... There is a nice <a href="http://en.wikipedia.org/wiki/Maxwell%27s_demon>tought http://en.wikipedia.org/wiki/Maxwell%27s_demon>tought experiment</a> linking thermodynamics to information theory. And guess what, experiments agree with the theory. After you have the theoretical framewok done, it is just a matter of applying the <a href="http://en.wikipedia.org/wiki/Boltzmann%27s_entropy_formula>Boltzmans http://en.wikipedia.org/wiki/Boltzmann%27s_entropy_formula&#... entropy formula</a>, and you are done.
- caf 14y agoWe know the minimum amount of energy required, because we exactly know the information content of a bit.