From: "Cordwell, William R" <wrcordw@sandia.gov> Don't know if you want to count this: "During the 1970s, David Lee, Douglas Osheroff and Robert Coleman Richardson discovered two phase transitions along the melting curve, which were soon realized to be the two superfluid phases of helium-3.[21][22] The transition to a superfluid occurs at 2.491 millikelvins (i.e., 0.002491 K) on the melting curve. They were awarded the 1996 Nobel Prize in Physics for their discovery." http://en.wikipedia.org/wiki/Helium-3
From Veit Elser: In 1991 a Finnish group (Hakonen et al.) discovered spontaneous ordering among the nuclear spins in silver at 560 picokelvins. That may still be the record, for observed phase transitions in ordinary bulk matter.
--yes, excellent. Helium-3 at 2491 microkelvins did not beat my earlier record at 325. The 560 picoK transition does, but I actually am not thrilled with it because I forgot to say I'm interested in atomic physics for this purpose, whereas this depended on nuclear physics. The point I wanted to use this record to make, was this. Naively speaking, the atomic physics energy scale is the Rydberg 13.6 eV energy, corresponding to T=105000 kelvin if E=(3/2)*kB*T. So a naive person might figure that any matter phase transitions are going to happen at about 100,000 kelvin. In fact they happen in at least some cases at temperatures 485,000,000 times colder. So the naive estimate can be quite wrong. My question is: just how wrong it can be. Is there any limit to the wrongness? Personally I doubt any limit is in sight. My rhodium superconductivity transition at 325 microkelvin presumably could be brought lower using some appropriate alloy of rhodium and something else, adjusted to optimize (pessimize?) it. On 12/11/13, math-fun-request@mailman.xmission.com <math-fun-request@mailman.xmission.com> wrote:
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Today's Topics:
1. Re: coldest place on earth (Eugene Salamin) 2. Re: coldest (David Makin) 3. Re: [EXTERNAL] coldest (Cordwell, William R) 4. Re: [EXTERNAL] coldest (Veit Elser) 5. coldest place, CO2 retraction (Warren D Smith)
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Message: 1 Date: Tue, 10 Dec 2013 18:53:13 -0800 (PST) From: Eugene Salamin <gene_salamin@yahoo.com> To: math-fun <math-fun@mailman.xmission.com> Subject: Re: [math-fun] coldest place on earth Message-ID: <1386730393.29707.YahooMailNeo@web162105.mail.bf1.yahoo.com> Content-Type: text/plain; charset=iso-8859-1
________________________________ From: Keith F. Lynch <kfl@KeithLynch.net> To: math-fun@mailman.xmission.com Sent: Tuesday, December 10, 2013 5:46 PM Subject: Re: [math-fun] coldest place on earth
Warren D Smith <warren.wds@gmail.com> wrote:
The interesting thing about this is that dry ice (froen carbon dioxide) forms at -78.5C (-109.3F) at Earth atmospheric pressures. Mars has a carbon dioxide seasonal "ice" cap. It would now appear that the Earth does too.
No.? That temperature is when CO2 frost will form with a partial pressure of CO2 of one atmosphere.? But of course only about 1/2500th of the air is CO2.? So if someone dropped a block of dry ice in that Antarctic valley, it would have sublimated, just like it would in your back yard.? Well, okay, maybe more slowly, but it certainly wouldn't have grown, much less appeared spontaneously.
Note that the partial pressure of CO2 on Mars is much higher than on Earth, since its atmosphere is 95% CO2.? In fact, if you neglected to pump the Mars air out of a room on Mars before filling it with Earth air, it would exceed the OSHA limit for human CO2 exposure.? If you teleported Mars's CO2 ice cap to Earth, keeping its temperature unchanged, it would quickly disappear.
Eugene Salamin <gene_salamin@yahoo.com> wrote:
All of space is filled with the 2.7 K cosmic microwave background.?
True.? That means an inactive object in space far from any other source of heat will (eventually) be at that temperature.? An active object can of course be warmer.
It requires shielding and active refrigeration to cool something to a lower temperature.
No.? An active object can also be *colder*.? Adiabatic expansion can turn a megakelvin gas cloud from a supernova explosion into a microkelvin gas cloud.? Atoms in the same vicinity within such a cloud started with the same speed and direction, so their relative speeds are much lower than in a 2.7 kelvin cloud.? Of course the cloud will eventually absorb the microwaves and warm up, but that could take a very long time, as a thin neutral gas is very transparent to microwaves and to almost everything else.
Spin temperatures, color temperatures, and information temperatures are metaphorical when taken out of context.? As Eugene Salamin pointed out, flipping a magnetic field can result in spin temperatures which are either negative or hotter than infinity, depending on your perspective.? But I don't think they can be used to heat or cool your home.? Nor can a microwave oven be used to freeze food, even though its radiation has a color temperature of less than one kelvin.? Nor can you start a fire with an x-ray machine even though its radiation has a color temperature of millions of kelvins.
As for information temperature, would you get more heat by burning a deck of punched cards containing the first million digits of pi or by burning a deck of punched cards containing a million random digits? (This is actually a surprisingly subtle question if you analyze it in enough detail.? Can Maxwell's Demon calculate pi?? And does it have a Szilard engine to play with?)
Answer:? You get the same amount of heat, since each digit on a punch card (in IBM format) removes 1 chad. ? --? Gene
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Message: 2 Date: Wed, 11 Dec 2013 03:02:35 +0000 From: David Makin <makinmagic@tiscali.co.uk> To: math-fun <math-fun@mailman.xmission.com> Subject: Re: [math-fun] coldest Message-ID: <D3E87CAC-C3D4-4E43-945B-1151DA990598@tiscali.co.uk> Content-Type: text/plain; charset=us-ascii
On 10 Dec 2013, at 23:22, Warren D Smith wrote:
(Was this really the coldest temperature in the universe? Perhaps there are natural refrigerators out there somewhere?)
Or more sophisticated alien ones....
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Message: 3 Date: Wed, 11 Dec 2013 14:17:24 +0000 From: "Cordwell, William R" <wrcordw@sandia.gov> To: math-fun <math-fun@mailman.xmission.com> Subject: Re: [math-fun] [EXTERNAL] coldest Message-ID: <D7A6AA7EB875854FB67699AAF1F5F0344011C4B5@EXMB03.srn.sandia.gov> Content-Type: text/plain; charset="us-ascii"
Don't know if you want to count this:
"During the 1970s, David Lee, Douglas Osheroff and Robert Coleman Richardson discovered two phase transitions along the melting curve, which were soon realized to be the two superfluid phases of helium-3.[21][22] The transition to a superfluid occurs at 2.491 millikelvins (i.e., 0.002491 K) on the melting curve. They were awarded the 1996 Nobel Prize in Physics for their discovery."
http://en.wikipedia.org/wiki/Helium-3
-----Original Message----- From: math-fun-bounces@mailman.xmission.com [mailto:math-fun-bounces@mailman.xmission.com] On Behalf Of Warren D Smith Sent: Tuesday, December 10, 2013 4:23 PM To: math-fun@mailman.xmission.com Subject: [EXTERNAL] [math-fun] coldest
This is the coldest place on Earth under natural conditions.? The coldest place on >Earth was in a physics experiment at a temperature of 50 nK.? This was touted as the >coldest place in the universe.
--In year 2000 a Finnish lab cooled a rhodium metal chunk to 100 picoKelvin.. http://ltl.tkk.fi/wiki/LTL/World_record_in_low_temperatures (Was this really the coldest temperature in the universe? Perhaps there are natural refrigerators out there somewhere?)
I am interested in the lowest temperature at which a physical system is known to undergo a phase transition. For example helium liquefying at 4.2K. Rhodium supposedly becomes superconductor at 325 microkelvins for example; that is much lower. I'd be interested in any lower-T candidates you can name (even speculative ones not yet demonstrated in lab).
A Bose-Einstein condensate gas phase consisting of approximately 2000 rubidium-87 atoms was made via laser cooling and trapping below 170 nanoK effective temperature, but I don't know if we should admit that, since it really was a highly unnatural form of "matter."
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Message: 4 Date: Wed, 11 Dec 2013 14:46:37 +0000 From: Veit Elser <ve10@cornell.edu> To: math-fun <math-fun@mailman.xmission.com> Subject: Re: [math-fun] [EXTERNAL] coldest Message-ID: <7429BC1A-9115-4212-B365-F2BA113D8A30@cornell.edu> Content-Type: text/plain; charset="us-ascii"
In 1991 a Finnish group (Hakonen et al.) discovered spontaneous ordering among the nuclear spins in silver at 560 picokelvins. That may still be the record, for observed phase transitions in ordinary bulk matter.
-Veit
On Dec 11, 2013, at 9:17 AM, "Cordwell, William R" <wrcordw@sandia.gov> wrote:
Don't know if you want to count this:
"During the 1970s, David Lee, Douglas Osheroff and Robert Coleman Richardson discovered two phase transitions along the melting curve, which were soon realized to be the two superfluid phases of helium-3.[21][22] The transition to a superfluid occurs at 2.491 millikelvins (i.e., 0.002491 K) on the melting curve. They were awarded the 1996 Nobel Prize in Physics for their discovery."
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Message: 5 Date: Wed, 11 Dec 2013 10:16:22 -0500 From: Warren D Smith <warren.wds@gmail.com> To: math-fun@mailman.xmission.com Subject: [math-fun] coldest place, CO2 retraction Message-ID: <CAAJP7Y0xkX6Fy2CHJW4pyVdiNjFW7hvACxa_bGQhpcCYK_LVkg@mail.gmail.com> Content-Type: text/plain; charset=ISO-8859-1
Warren D Smith <warren.wds@gmail.com> wrote:
The interesting thing about this is that dry ice (froen carbon dioxide) forms at -78.5C (-109.3F) at Earth atmospheric pressures. Mars has a carbon dioxide seasonal "ice" cap. It would now appear that the Earth does too.
From: "Keith F. Lynch" <kfl@KeithLynch.net> No. That temperature is when CO2 frost will form with a partial pressure of CO2 of one atmosphere. But of course only about 1/2500th of the air is CO2. So if someone dropped a block of dry ice in that Antarctic valley, it would have sublimated, just like it would in your back yard. Well, okay, maybe more slowly, but it certainly wouldn't have grown, much less appeared spontaneously.
--aha yes, good point... BUT, what we need to know, then, is "what is the sublimation temperature of dry ice at 1/2500 atm CO2 gas pressure?" The phase diagram of CO2 is here http://www.teamonslaught.fsnet.co.uk/co2%20phase%20diagram.GIF and a better diagram for us since it uses a log scale for pressure, is http://www.cgenpower.com/images/other/pop-up/fasendiagram.jpg and it would appear from extrapolating the latter diagram, that to get stable solid CO2 at 1/2500 bar of vapor pressure, you'd need to be at temperature of about minus 150 celsius. The antarctic record of minus 94 C was not cold enough.
So, sorry for my wrong claim; I now agree with Lynch.
Note that the partial pressure of CO2 on Mars is much higher than on Earth, since its atmosphere is 95% CO2.
--the atmospheric pressure on Mars allegedly is about 8.7% of Earth's so again I agree with Lynch.
It requires shielding and active refrigeration to cool something to a lower temperature than 2.7K.
No. An active object can also be *colder*. Adiabatic expansion can turn a megakelvin gas cloud from a supernova explosion into a microkelvin gas cloud. Atoms in the same vicinity within such a cloud started with the same speed and direction, so their relative speeds are much lower than in a 2.7 kelvin cloud. Of course the cloud will eventually absorb the microwaves and warm up, but that could take a very long time, as a thin neutral gas is very transparent to microwaves and to almost everything else.
--really? I mean, is there really a gas cloud from some supernova that is microkelvin? Or is this just a speculation? I agree with Lynch on the general principle that an active object could get below 2.7K, but does it actually happen someplace? For example, is that Finnish lab that got 100 picoKelvin, really the coldest place in the universe?
To make a completely crazy scenario, let's say we have a neutron star that has planets orbiting it. (It is known from pulsar timings that such exist.) After a long time, the planet gets cold, approaching 2.7K. Now further suppose that the planet is totally magnetized by the enormous magnetic field of the neutron star, which far exceeds any magnetic field we can make on Earth. Now a rogue planet swoops in from outer space and gravitationally interacts with our planet, causing it to escape from neutron star. As a result, it experiences demagnetization cooling. Maybe in this way temperatures way below 2.7K could be reached naturally. I'm dubious, but it might be possible.
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