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Note from micronesia: please read the thread before making comments about how we have just turned physics on its head. |
On January 06 2013 00:51 DarkPlasmaBall wrote:
I don't have a strong background in chemistry, but I had my mother read this article, and she's been teaching chemistry for about 30 years now. She doesn't really seem too concerned. If I've understood this correctly, Kelvin is just a conversion and measurement, and not actually a degree, and so it would seem sensible to just redefine absolute zero as the new established low point (recently discovered here) and change the conversion scales between Kelvin and Celsius/ Fahrenheit (since -273.15 degrees Celsius was originally found using estimates and graphs and asymptotes to begin with), as absolute zero is simply defined as the lowest possible temperature. It would seem silly to have negative Kelvin, because its null point is, by definition, absolute zero.
It's not that. The Kelvin is still accurate and nothing needs to be changed. As explained, this temperature is not colder than absolute zero, it's just convenient to express the state with a negative number because of the definition of entropy.
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On January 06 2013 00:41 Snorkels wrote:Show nested quote +On January 06 2013 00:38 CursOr wrote:On January 06 2013 00:33 ThomasjServo wrote:
Well guys, we broke the universe. I hope you all are happy with yourselves. LOL Nerd Chills. ^_^ WP I've wondered in the last year or so why breaking a hard barrier of the speed of light is a well known science fiction trope but the absolute zero barrier is unexplored. It should be interesting to see what can be influenced by this new knowledge.
There's something in one of the Dune books about freezing a material to a negative temperature. Totally a minor detail that doesn't matter for the plot, but I thought it was pretty cool when I read it. Unfortunately can't remember which book.
Edit: Heretics of Dune.
"His dart throwers had been sealed and "washed"
against snoopers, then maintained at minus 340[degrees] Kelvin in a
radiation bath for five SY to make them proof against snoopers."
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Oh wow, I expected that they went a bit below 0 kelvin, and they got a few billionths below absolute zero? Sick !
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On January 06 2013 00:40 FluffyBinLaden wrote:
Science is confusing. The lack of... absoluteness even in the absolutes... it's strange.
It's an interesting thought.
there is only "absoluteness" in universe until the point of time at which you develop the medium to conceive a new degree of "absoluteness"
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On January 06 2013 01:37 BillClinton wrote:Show nested quote +On January 06 2013 00:40 FluffyBinLaden wrote:
Science is confusing. The lack of... absoluteness even in the absolutes... it's strange.
It's an interesting thought. there is only "absoluteness" in universe until the point of time at which you develop the medium to conceive a new degree of "absoluteness"
We're pretty certain about absolute zero and the speed of light being fixed. Science isn't philosophical mysticism like you're implying.
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On January 06 2013 01:42 Solarsail wrote:Show nested quote +On January 06 2013 01:37 BillClinton wrote:On January 06 2013 00:40 FluffyBinLaden wrote:
Science is confusing. The lack of... absoluteness even in the absolutes... it's strange.
It's an interesting thought. there is only "absoluteness" in universe until the point of time at which you develop the medium to conceive a new degree of "absoluteness" We're pretty certain about absolute zero and the speed of light being fixed. Science isn't philosophical mysticism like you're implying.
Science is also not rigid or fixed. Its a constantly evolving philosophy to explain how the Universe works. I should hope both of those things would be dis-proven over time as it signifies that we're still evolving our knowledge base.
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On January 06 2013 01:42 Solarsail wrote:Show nested quote +On January 06 2013 01:37 BillClinton wrote:On January 06 2013 00:40 FluffyBinLaden wrote:
Science is confusing. The lack of... absoluteness even in the absolutes... it's strange.
It's an interesting thought. there is only "absoluteness" in universe until the point of time at which you develop the medium to conceive a new degree of "absoluteness" We're pretty certain about absolute zero and the speed of light being fixed. Science isn't philosophical mysticism like you're implying.
Earth not being flat was once thought to be "mysticism" as well (when you use the term "we", who do you mean?)
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I am a grad physics student and even with that i found that article quite blur.
I really don't understand how some of you can debate about what's told in that article with statements as confidents and "clear" .
One has to be really cautious with signs and their interpretation in physics equations. In particle physics you can encounter something which looks like particles with negative energy going backward in time when it's antiparticles with positive energy going forward in time.
There are also a lot of understanding problems because people don't talk about the same things because they don't use the same definitions.
So just an advice when you read articles like these, don't take it for granted.
And Solarsail, speed of light and absolute zero are fixed in the framework of the THEORY we built to describe what we see. One could build a theory where these are not fixed even if it might take complicated tricks or "laws" to match the observations back.
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On January 06 2013 01:51 sCCrooked wrote:Show nested quote +On January 06 2013 01:42 Solarsail wrote:On January 06 2013 01:37 BillClinton wrote:On January 06 2013 00:40 FluffyBinLaden wrote:
Science is confusing. The lack of... absoluteness even in the absolutes... it's strange.
It's an interesting thought. there is only "absoluteness" in universe until the point of time at which you develop the medium to conceive a new degree of "absoluteness" We're pretty certain about absolute zero and the speed of light being fixed. Science isn't philosophical mysticism like you're implying. Science is also not rigid or fixed. Its a constantly evolving philosophy to explain how the Universe works. I should hope both of those things would be dis-proven over time as it signifies that we're still evolving our knowledge base.
Exactly, you can only use the operants which are system immanent. Math is also "only" a system which can be true until the basic axioms (Einstein), thats why science can be considered some kind of belief too. You should be careful using "absolute" terms describing "reality" (whatever it really is or seem to be). When you use "absolute" terms in science its only to have some form of standardisation which enables you to work more efficiently (or work at all) [respectively religious belief systems].
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Thanks for the clear explanation of negative temperature. Don't remember my thermodynamic lecturer ever mention negative temperatures at all.
On January 06 2013 00:41 micronesia wrote:Show nested quote +On January 05 2013 23:57 Fruscainte wrote:
Physics itself is being rewritten gentlemen. We have broken the seemingly impossible to break barrier in temperature, and may have the ability to replicate Dark Energy-esque forces in a lab. We have been able to get negative temperatures since before this paper.... it is just the first time it was done with a gas, I believe. The common understanding of temperature that it is a measure of the speed of the motion of molecules in a system, while useful, is not accurate. You can actually define temperature using this formula: 1/T = dS/dU where S is entropy and U is internal energy. Temperature therefore has to do with how a change in internal energy relates to a change in entropy. For normal systems (positive Kelvin temperatures) increasing energy of a system will increase entropy (this is very important for studying the Carnot Cycle). For systems where the opposite happens (negative temperature), the object will give off heat to any system it comes into thermal equilibrium with. A few cases: System A System B ResultWarm Hot Heat flows from hot to warm; temperatures equalize Negative Warm Heat flows from negative temperature system to warm system Negative Very Hot Heat flows from negative temperature system to hot system Another example where you can get negative temperature: Place a 2-state paramagnet into a magnetic field such that the dipoles align. Then, reverse the magnetic field polarity.
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On January 06 2013 01:23 Solarsail wrote:Show nested quote +On January 06 2013 00:51 DarkPlasmaBall wrote:
I don't have a strong background in chemistry, but I had my mother read this article, and she's been teaching chemistry for about 30 years now. She doesn't really seem too concerned. If I've understood this correctly, Kelvin is just a conversion and measurement, and not actually a degree, and so it would seem sensible to just redefine absolute zero as the new established low point (recently discovered here) and change the conversion scales between Kelvin and Celsius/ Fahrenheit (since -273.15 degrees Celsius was originally found using estimates and graphs and asymptotes to begin with), as absolute zero is simply defined as the lowest possible temperature. It would seem silly to have negative Kelvin, because its null point is, by definition, absolute zero. It's not that. The Kelvin is still accurate and nothing needs to be changed. As explained, this temperature is not colder than absolute zero, it's just convenient to express the state with a negative number because of the definition of entropy.
Silly sensationalism then ^^
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On January 06 2013 02:25 DarkPlasmaBall wrote:Show nested quote +On January 06 2013 01:23 Solarsail wrote:On January 06 2013 00:51 DarkPlasmaBall wrote:
I don't have a strong background in chemistry, but I had my mother read this article, and she's been teaching chemistry for about 30 years now. She doesn't really seem too concerned. If I've understood this correctly, Kelvin is just a conversion and measurement, and not actually a degree, and so it would seem sensible to just redefine absolute zero as the new established low point (recently discovered here) and change the conversion scales between Kelvin and Celsius/ Fahrenheit (since -273.15 degrees Celsius was originally found using estimates and graphs and asymptotes to begin with), as absolute zero is simply defined as the lowest possible temperature. It would seem silly to have negative Kelvin, because its null point is, by definition, absolute zero. It's not that. The Kelvin is still accurate and nothing needs to be changed. As explained, this temperature is not colder than absolute zero, it's just convenient to express the state with a negative number because of the definition of entropy. Silly sensationalism then ^^
It's not sensationalism, it's just... people are misunderstanding something because they never took a statistical mechanics / thermodynamics course. We got to negative temperature. Great. Does it ever say the system got to absolute zero? No. It never "passed through" absolute zero, think of it as hopping over it. If you define temperature using entropy, this is possible in systems with a finite number of states. So why would we redefine absolute zero? It is still a temperature that we cannot get to with any non-trivial system.
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Wow that's so cool! Doesn't this have some renewable energy implications?
Next thing I wanna see is something smaller than Planck length. And man-made UFOs, of course. Y'know, those things that can effortlessly escape Earth's gravity.
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I think this will have a great impact on the upcoming episodes of the Big Bang Theory!!
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On January 05 2013 23:57 Fruscainte wrote:
if part of the cloud is at a negative absolute temperature, some atoms will move upwards, apparently defying gravity4.
errm.. dont know if you guys missed that? Isn't this the really interesting part about this? Or does it sound more spectacular than it is?
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On January 06 2013 00:43 micronesia wrote:Show nested quote +On January 06 2013 00:41 Whitewing wrote:
Okay so, they are hitting a temperature below it by looking at the definition in a cute fashion, but they aren't actually able to hit absolute zero perfectly either.
Still impressive though. This is true. It's easier to get a negative temperature than absolute zero. We have gotten very close to absolute zero from the positive direction though! (millionths of a kelvin, I believe) Show nested quote +On January 06 2013 00:43 emythrel wrote:
a few billionths below aboluste zero? phew. For a second i thought we had again discovered that we were completely wrong about the universe. While a few billionths is a massive deal, its not like they managed to go a whole degree below or further, which would mean a complete re-write of some major components of modern physics. I think you are misunderstanding what this means. It's not that we broke physics, but so minorly that it can be written off... it's that the conventional understanding of temperature is incorrect. I realized this when I studied thermal physics, well before this article.
![[image loading]](http://i248.photobucket.com/albums/gg169/Myrkskogg/cooled_zps23104d59.jpg)
User was warned for this post
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^Lol.
So.. to clarify this for the layman.
Supposing my finger was a perfect measure of how hot or cold something was and was capable of feeling any temperature without being permenantly damaged, and ignoring the changes caused by me sticking my fingers in there and any other sort of technical details:
If I touched something that was the coldest we've "achieved" previously, which I understand is slightly above absolute zero,
It would feel very cold.
If I touched something that was actually absolute zero,
It would feel slightly colder.
If I touched this new "negative temperature"...
It would feel even colder still?
I'm still unsure as to whether they've actually created something at a temperature colder than what we previously understood to be absolute zero or if due to technical definitions of what temperature actually means this has to be a "negative" temperature or a temperature "below" absolute zero.
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lol what a misleading yet accurate title. I guess this is what happens when the common person (even the common educated person) doesn't understand the more technical definitions of a field. It's times like this, I'm glad I took those pchem classes @_@
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On January 06 2013 01:13 micronesia wrote:
I want to point out that saying entropy is the disorder of a system is about as accurate as saying temperature is the speed of molecules in a system. Thermal physics is difficult to discuss without studying it.
No, entropy is pretty much the disorder in a system when you define order as having structure.
That's about all you really need to know at the quantum mechanical level, certainly enough to understand how this works.
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EPT
