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Note from micronesia: please read the thread before making comments about how we have just turned physics on its head. |
United States24667 Posts
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)
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.
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can't go faster than the speed of light? make the speed of light faster
cant go colder than absolute zero? decrease absolute zero
ezpz
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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.
pretty simple, because there are ways around the light barrier, such as warping space. Unfortunately, there is still no known or theorised way to go below absolute zero, what would u gain from it anyways? Travelling past light speed is needed for most sci-fi, below absolute zero temperatures are not.
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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.
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Okay. I'll do a quick TLDR for the people who aren't in this field.
Absolute zero is a misnomer as far as physicists are concerned. We only really consider temperature as a thermodynamic process where we can define temperature as a relation between entropy and energy where entropy is the disorder within a system (where disorder is defined by physicists as the degree to which a system is seperated from a perfectly spread, entirely equal medium). The ultimate entropic system is one where all energy is spread through an entire body of the system in perfectly equal amounts and any distribution demonstrated on this system is FLAT.
What this means in laymans terms is if you imagine that the universe is full of strings of lumpy custard, a perfectly entropic universe is not only perfectly smooth but has absolutely no heat flow at all.
When considering entropy, when you increase the temperature of an atom, the electrons preferentially distribute themselves up through increasing energy levels and entropy thus increases with temperature. In the case of negative temperature, as I understand it, a decreasing negative temperature preferentially fills the HIGHER energy shells and not the lower energy shells. This implies a bound higher energy state which if considered in the perspective of a system which is collapsing, will administer a repulsive anti-collapsing potential.
Essentially, the way to think of it is that normally when you increase the temperature of a system, you fill a glass from the bottom up. With negative temperature, it is the equivalent of taking that same glass and filling it and finding it actually fills from the top down.
Very interesting stuff. The paper is fascinating too. Something at negative temperature is going to be fighting local attempts to be at a positive temperature and thus reach a steady state.
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People are not understanding this correctly at all. They didn't break the previous attempt to achieve absolute zero. Instead they played with the mechanics of physics and thus created a situation with negative temperature. The two scenarios don't really align in their idea of temperature. The entropy, or the measure of disorder, created the negative temperature in this case. This is a big deal but has been done before as previously stated. The article just blew this out of proportion by saying we got below 0 kelvin.
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On January 06 2013 00:43 Ikidomari wrote:
can't go faster than the speed of light? make the speed of light faster
cant go colder than absolute zero? decrease absolute zero
ezpz
That's why scientists raised the speed of light in 2208. - Professor Hubert J. Farnsworth
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On January 06 2013 00:55 lightrise wrote:
People are not understanding this correctly at all. They didn't break the previous attempt to achieve absolute zero. Instead they played with the mechanics of physics and thus created a situation with negative temperature. The two scenarios don't really align in their idea of temperature. The entropy, or the measure of disorder, created the negative temperature in this case. This is a big deal but has been done before as previously stated. The article just blew this out of proportion by saying we got below 0 kelvin.
No, they are actually quite right in how they describe it. The main problem is most people don't understand how physicists define temperature. The paper attributes the opposite property to the commonly thought one - where entropy is a function of temperature. Instead, temperature is defined as a function of entropy and energy which is how we can arrive at negative temperatures.
They aren't stating what they think most people think they are (where a negative temperature implies negative energy) though the effect might ultimately be similar.
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wow :O, I'm interested in future experiments of that stuff
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Oh, I would also note that they demonstrated that said temperature is stable in the region of around 0.6s. Which if you think in physics terms is an eternity.
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Are there any possible application of this?
Superconductors are thanks to cold physics right? Anything else?
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Ok, at the beggining I thought this was a troll post, then I read the paper and was very impressed, then I read the wiki page and found out this has been known and done for a while.. Still very interesting.
As others are pointing out, these guys 'just' created a quantum system that decreases in entropy the more energy you apply, instead of the other way around, which is what you would expect of a classical system. Since the quantity driving this conversion is temperature, they call it a negative temperature system, because it's what the math model needs to explain this behavior.
Nothing too extremely ground-breaking, but still very interesting when they mention that the system has negative pressures, and makes me wonder if this could have some hand in solving the dark energy/missing antimatter problems.
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wow this is a pretty interesting discovery, things like these add up in my opinion over time
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United States24667 Posts
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.
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ahhhhhh myy god. That's actually really cool. It's amazing what we can do and prove with quantum physics. It has really opened up a whole new world of study! With this type of technique, creating anti-gravity could be a possibility in the future. Imagine flying cars that use anti-gravity as their main source of flying.
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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.
What do/did you study btw? I'm currently 4th here Chem Eng student and I can't agree with this more. Thermal physics is a ball ache even when you study it :<
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MIT, breaking physics one experiment at a time  . A bit misleading as others have said, but nonetheless an important and groundbreaking feet.
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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.
oh dear god tell me about it. Unfortunately nobody cares about such minor details when its psychology or philosophy people are talking about. But for natural sciences, the plausibility of this concept reveals itself to all but the most dense people. For that, I envy natural scientists. Unfortunately though, we are on TL General, so Id expect a great deal of random comments from people nearing high school graduation on whatever topic possible.
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Guys guys, in first year thermodynamics you learn about negative temperatures, it is nothing new. This is just in a gas, not in the classical sets of arranged dipoles or similar. Don't panic.
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EPT
