Closest to Absolute Zero

[CanadaAotS]

I've been searching around for the closest anyone's gotten to absolute zero...

 

I can't find it now (forget what I searched for lol) but there was one dated 2003 that said 500 picoKelvins...

 

I just want to know exactly how close to absolute zero anyone has been able to reach...

[ecoli]

Modern experimenters achieve temperatures measured in hundred billionths of a degree above absolute zero. This is achieved in dynamic environments. It has not yet been possible to achieve temperatures below 1 μK in equilibrium.

 

http://en.wikipedia.org/wiki/Coldest_temperature_achieved_on_earth

[CanadaAotS]

I guess the key phrase their is "in equilibrium" lol.

[rakuenso]

Only in this exceptional cold will helium turn into a liquid (at −269 C). Onnes achieved this feat first. He received a Nobel Prize for his efforts.

 

Man how the bloody hell do you turn helium into a solid then

[gib65]

I've reached minus 30 celcius. Damn, that was a cold day!

[GrandMasterK]

What's liquid helium look like? Is it dangerous other then the fact if you touch it you can kiss your hand good bye?

[swansont]

I guess the key phrase their is "in equilibrium" lol.

 

I think they are leveraging some semantics with that phrase. The question is what is meant - with what do you have to be in equilibrium?

 

You can get to a microK with laser cooling, and the atoms will be in equilibrium with the photon field from the laser, but not with anything else in the vicinity.

 

When forming a Bose-Einstein condensate you evaporatively cool the ensemble. It can't reach equilibrium with the surroundings, because nothing else around is that cold, but ideally it isn't interacting with anything but the magnetic trap that confines them. When they condense they drop into the ground state the description of them has to be quantum-mechanical, so claiming that they aren't in equilibrium isn't quite fair.

[GrandMasterK]

Another question, I know Bose-Einstein Condensate is a solid but what does it look like?

[timo]

Another question, I know Bose-Einstein Condensate is a solid ...

Are you sure about that? If I remember correctly, there is no interaction term in the theoretical description of Bose-Einstein condensates (ideal gas approach). So there´s no reason why the particles should bond to form a solid.

 

... but what does it look like?

A basic, very easily understandable but yet (to my limited knowledge) correct description of Bose-Einstein condensates can be found here: http://www.colorado.edu/physics/2000/bec/

 

But to briefly give my opinions on "what does it look like?": To see something you have to have photons being reflected by it. However, in this case you have to have a way of "illuminating" the BEC with photons without heating it up in the process. I don´t know to which extend this is feasible. Perhaps the link I gave in above does have some answers.

[swansont]

Another question, I know Bose-Einstein Condensate is a solid but what does it look like?

 

It's actually still a gas, sort of. Many consider it a new and different state of matter.

[jdurg]

What's liquid helium look like? Is it dangerous other then the fact if you touch it you can kiss your hand good bye?

 

Liquid helium is a clear liquid which does not experience any type of frictional resistance. Hence if you had a jar of the stuff, it would actually move up the sides of the jar and outwards. Solid helium can be achieved, but only at substantially higher pressures and insanely low temperatures.

[Daecon]

Helium is clear?

 

I thought Helium was metallic...

[swansont]

Helium is clear?

 

I thought Helium was metallic...

 

It's a noble gas. Or in this case, a noble liquid.

[Daecon]

*slaps forehead*

 

Oh yeah, of course it is!

 

What was I thinking of then, Hydrogen...?

[swansont]

Yes, solid hydrogen can have metallic properties. (Wiki entry on the topic)

[Orbit]

I heard abousloute zero was -273 celius.

[Klaynos]

0K (absolute zero) = −273.15 °C = −459.67 °F

[silkworm]

My physics professor does research with liquid Helium as a supercondutor. He has gotten it down to 0.00001K. I have no idea what that is in the pico- micro- prefix world. But that's been the lowest I've heard. He also does it with a machine he built himself out a scrap junk, so needless to say that I'm impressed.

 

What's liquid helium look like? Is it dangerous other then the fact if you touch it you can kiss your hand good bye?

 

I wonder if liquid Helium is different, but you have a second to touch liquid nitrogen. The same guy had me stick my hand in liquid nitrogen and tell him what I felt. It feels like a little gentle vacuum cleaner, you feel nothing, and and when you bring your hand out it's not wet. You can do this (over short times) because your hand is initially warm enough to give you a protective zone of vaporized nitrogen around it. If you do wait to long and the nitrogen does touch you you will get burned badly, but you have a quick second. For anyone who hasn't done it I suggest it, though not at home.

[ecoli]

@ silkworm... has he written any paper's about it, or anything? sounds interesting.

[silkworm]

Oh yes, he's written a ton of them. He's a workaholic.

 

I can't tell you where he's been published, I've seen articles here and there that he's shown me and where his work was published in books.

 

His name is Dr. James Ho from Wichita State University. Here's a brief bio about him from the university:

 

Dr. James C. Ho (PhD, University of California, Berkeley), Trustees Distinguished Professor. His main interest centers around low-temperature calorimetry and superconductivity. Through extensive collaborations and an interdisciplinary approach, he also conducts basic and applied research on magnetic and high-strength materials. Recent efforts include the elucidation of magnetic ordering in cuprate superconductors and related compounds, as well as the development of MRI-compatible aneurysm clips for neurosurgery. Overall, Dr. Ho has 170 journal articles and 159 papers presented at national or international conferences.

 

I love the man to death, so I'm sad I can't give you more direction. He also doesn't have a page on wichita.edu that gives his publications like the other instructors. Next time I talk to him I'll get more specific info on where he's been published and pass it along.

[Klaynos]

One of our research teams does research on something very similar to that...

 

Although in our case the liquid helium is just used to cool other samples and not tested on itself...

 

You can have liquid nitrogen on your hand for about 3 seconds, the only time it's particually dangerouse is if it gets mixed with your cloths, which allows it to be closer to your skin for longer :|

[ecoli]

You can have liquid nitrogen on your hand for about 3 seconds' date=' the only time it's particually dangerouse is if it gets mixed with your cloths, which allows it to be closer to your skin for longer :|[/quote']

 

yeah, that's a weird feeling.

[Klaynos]

I walked out into a corridor the other day into a pool of it Looked like a scene from some old mad scientist film...

[starbug1]

I know that liquid helium is much colder than liquid nitrogen, but how much more dangerous is liquid helium is it makes contact with skin?

[Daecon]

Um... what happens when you bring liquid water into contact with something that has a temperature of about one Kelvin...? Something catastrophic, I'd imagine - and from what I remember a large percentage of the human body is liquid water too, so...