Cold, or Coldness refers to the condition or subjective perception of a relatively low level of heat energy, measurable by temperature scales, with a lower bound to temperature at absolute zero, defined as 0 K on the Kelvin scale, an absolute thermodynamic temperature scale. This corresponds to −273.15 °C on the Celsius scale, and −459.67 °F on the Fahrenheit scale. Metaphorically "coldness" can indicate emotional indifference or lack of empathy, contrasted with "warmth" of affections, or "heat" of passions.
- A cold coming they had of it, at this time of the year; just the worst time of the year to take a journey, and specially a long journey, in.
- Lancelot Andrewes, Sermon 15, Of the Nativity (1622).
- Do you wish to honor the Body of the Savior? Do not despise it when it is naked. Do not honor it in church with silk vestments while outside it is naked and numb with cold. He who said, “This is my body,” and made it so by his word, is the same that said, “You saw me hungry and you gave me no food. As you did it not to the least of these, you did it not to me.” Honor him then by sharing your property with the poor. For what God needs is not golden chalices but golden souls.
- If I was not assured by the best authority on earth that the world is to be destroyed by fire, I should conclude that the day of destruction is at hand, but brought on by means of an agent very opposite to that of heat.
- Charles Dodgson (bishop) quoted in Life and Letters of Lewis Carroll (1898), p. 5
- People ask the way to Cold Mountain.
Cold Mountain? There is no road that goes through.
Even in summer the ice doesn't melt;
Though the sun comes out, the fog is blinding.
How can you hope to get there by aping me?
Your heart and mine are not alike.
If your heart were the same as mine,
Then you could journey to the very center!
- Hanshan, as translated by Burton Watson, in Cold Mountain: 100 Poems by the T'ang Poet Han-shan (1970)
- Here I stand
In the light of day!
Let the storm rage on!
The cold never bothered me anyway!
- Despite the growing interest in the ﬁeld of ultracold chemistry, experimental progress has been hampered by a lack of appropriate methods to trap and cool molecules. Laser cooling, while very successful, is limited to a small number of atoms in the Periodic Table because few atoms and no molecules have closed cycling transitions. The main methods to produce cold molecules of chemical interest can be divided into two groups. Buffer gas cooling relies on collisions with cold helium in a dilution refrigerator to cool paramagnetic molecules and trap them in a magnetic trap. Super-sonic expansion is used by other methods to precool the molecules. The resulting cold molecular beams have been slowed and trapped in some experiments by interactions with pulsed electric ﬁelds Stark decelerator, by interactions with pulsed optical ﬁelds, by spinning the nozzle, and by billiardlike collisions. Finally, laser-cooled alkali-metal atoms are used to produce cold molecules via photoassociation. None of these methods have, to date, achieved the phase space densities required to observe reaction dynamics at ultracold temperatures.
We recently demonstrated a general method to stop and eventually trap paramagnetic atoms. Our method is based on the interaction of a paramagnetic particle with pulsed magnetic ﬁelds. It operates in analogy with the Stark decelerator by reducing the kinetic energy of a para-magnetic atom passing through a series of pulsed electro-magnetic coils. The amount of kinetic energy removed by each stage is equal to the Zeeman energy shift that the atom experiences at the time the ﬁelds are switched off.
- Future work will extend the coilgun method to trap molecules of chemical interest. Once they are in a magnetic trap, they can be cooled to near the single photon recoil limit using the method of single photon cooling, as demonstrated recently with trapped atoms. The application of this method to cooling of molecules is particularly promising.
- Edvardas Narevicius, Adam Libson, Christian G. Parthey, Isaac Chavez, Julia Narevicius, Uzi Even, and Mark G. Raizen; “Stopping supersonic oxygen with a series of pulsed electromagnetic coils: A molecular coilgun” in Physical Review A 77(5) • (May 2008).