By Davide Castelvecchi
In his article "Demons, Entropy and the Quest for Absolute Zero," physicist Mark G. Raizen describes how to cool a rarefied gas down to temperatures of just millionths of a degree above absolute zero. The starting point is to take a gas that has already been cooled to one one-hundredth of a kelvin (using a device called an atomic coilgun, also described in the text) and place it in a magnetic trap. Then the serious freeze can begin, using the new technique of single-photon cooling.
Single-photon cooling exploits a one-way gate inspired by a 19th-century thought experiment by James Clerk Maxwell. The great Scottish physicist theorized the existence of a "demon" that seemed able to concentrate the atoms of a gas into a smaller volume without raising their temperature, thus reducing their entropy. That feat seemed to violate the second law of thermodynamics, according to which entropy can never decrease. (What's the catch? Read the article to find out.)
Raizen's idea is that a one-way gate can help cool a gas in two steps: First let the gate concentrate atoms into a smaller volume (but without raising their temperature), then allow them to expand to the original volume (which brings their temperature down).
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7 Comments
Add CommentWill the Red beam cause "tunneling effect"?
Reply | Report Abuse | Link to thisi mean, the Red beam can act as a barrier to the right red atoms, and then a number of them can pass from the red beam to the left... is it possible to happen?
The red laser beam has to impart energy to the atoms it interacts with. Wouldn't that raise the temperature of those atoms? Even though you are confining the atoms using the red beam they would have a greater energy in that area. Even when they expanded into the original area they would still be carrying the energy imparted by the red laser. I don't see how any cooling would take place. Am I missing something here?
Reply | Report Abuse | Link to this--Michael
Separation of molecules by type is part of a real method to bypass the second law. Separating molecules requires less work than is gained as a result of the separation.
Reply | Report Abuse | Link to thisIncredibly, instead of using lasers, a more useful version of the method involves mechanically separating steam from air, for example. As steam is separated from air, it condenses, which pumps heat.
The second law does not actually limit separation of molecules by type. The second law only limits extraction of work by gas expansion.
A simple phenomenon is the temperature Cold. All cells, quarks, nuclei, blood, earth etc produce cold from their poles. We see this on our planet what we don't detect is the cold from the poles of say a skin cell. The ratio of cold emitting from cells is so minute as to go unnoticed except of course the big cell Earth.
Reply | Report Abuse | Link to thisEvery cell has a nucleus with orbiting bits of itself (nuclei) and individually con zillions of these are in harmony with the cell until a reaction causes the particles to repel one another. Individually these particles have the same energy as the parent two poled cell. Now you will notice the cold being produced.
As an example take an air cell and cause a reaction! OK just blow on your hand.
Man discovered that temperature interacted with mercury and the thermometer was born, I know, I know this is not making sense but hang in there. The house is hot as heck so you have a fan cooling a room. Coming from the hot bathroom its refreshing to get back to your cooled room. The thermometer taken from the bathroom reads 40 degrease and now in the cooled room reads 38 degrease. Next day (hot as heck) the bathroom reads a hot 38 and the comfortable room with fan reads 36. OK now this is my discovery. ---
The fan in the room is causing a reaction that has air cells chipping, in other words that one cell that produces cold from its poles is now producing cold from the co zillion poles of its chips.
Because Forces of Equal Evolution act Upon Forces of Equal Evolution the cold producing chips or molecules of air do not interact with the mercury of your thermometer. This explains the mystery of wind chill.
cbc.ca bruce voigt
I cannot understand why the orange beam always bounce back the atoms in the red state. Doesn't the beam bounce forward the atoms at the same possibility?
Reply | Report Abuse | Link to thisHow can I download the animation?? It could be very usefull in my presentation
Reply | Report Abuse | Link to thisEr... are you sure?
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