Alman bilim insanları, mutlak sıfırın altına inmeyi başardılar.

[Mesudi 0]

Alman bilim adamları, "olası en soğuk ısı derecesi" kabul edilen "mutlak sıfır"ın altına inmeyi başardıklarını açıkladı.

"Science" dergisinde yayımlanan araştırmaya göre bilim adamları, ilk kez mutlak sıfırın altında bir atomik gaz üretti.

Detaylar için,

KAYNAK: http://ekonomi.haberturk.com/teknoloji/haber/809642-istanbuldaki-soguksa-bu-nedir

[CharlesDarwin 0]

Bu mümkün olabilir mi? Mutlak 0 a inilmesinin imkanı yok derken bir de altına inilmesi. Bana pek mümkünmüş gibi gelmedi.

[CharlesDarwin 0]

Durum bizim anladığımızdan biraz farklı sanırım:

http://www.sciencedaily.com/releases/2013/01/130104143516.htm

[haci 0]

ABSOLÜ SIFIR NEDİR?

Absolü sıfır ulaşilamayacak bir sayı olup hesaplanarak ulaşılan bir değerdir. Kimse tarafından ölçülmemiş olan bir kavramdır.

Tarihçesi 1661 yılında Robert Boyle'a kadar uzanır. Gazlarla uğraşan Boyle, 1661 yılında havanın basıncı (P) ile hacminin (V) çarpımının, geniş bir yelpazede dalgalanmasına rağmen, belli sıcaklıklarda sabit olduğunu bulmuş ve gözlemini şu formülle ifade etmiştir.

PV=SABİT (CONSTANT)

Daha sonraları yapılan araştırmalar Boyle kanunun bir istisna dışında, sadece takribi olduğunu göstermiştir. İstisna çok düşük basınçlarda yapılan ölçümlerdir. Çok düşük basınçlarda Boyle'ın formülü doğru sonuç vermektedir.

1800 yılında Charlese ve Gay-Lussac adında iki sivri akıllı basınç aynı tutulsa da gazların hacminin ısı ile arttığını bulmuş ve buna Charles kanunu denmiştir. Buna göre:

V=V0(1+at)

V=Volum. Yani (t) ısısındaki hacim.

VO=0 Santigrad derecedeki hacim.

a= alfa termal genişleme kofaktörü.

t= temparatür.

Bu kanunu bulan Charles ve Gay-Lussac'a göre, a (alfa) her gaz için aynı değere sahiptir.

Charles kanunu da, Boyle kanunu gibi kesin olmayıp takribidir ama, çok düşük basınç sınırında kesinleşmektedir. Bu kesinleşme anında a'nın değeri 0,003661=1/273,15 olmaktadır.

Bu değeri yukardaki formüle yüklersek, görürüz ki temperatürün -273,15 santigrad derece olduğu zaman gazların hacmi sıfıra inmektedir.

Bu nedenden dolayı -273,15 derece absolü sıfır olarak kabul edilmiştir. Bu temperatürün altına inmenin mümkün olmadığı sonucuna varılmıştır.

Şu anda uzayın temperatürü -270 C derecedir. 13,7 milyar yıl önce son derece sıcak bir objenin genişlemesinden oluşan Big Bang uzayı ısıtmış ve bu sıcaklık hızla düşmeye başlamıştır.

Bu soğuma aslında saniyenin küsürü içinde gerçekleşmiş ve bu sırada enerji maddeye dönüşmüştür. Faz değişimine maruz kalan sıcak enerji maddeye dönüşürken düşen sıcaklığa bağlı olarak çesitli atomaltı parçacıklar ortaya çiıkmışlardır. Bu parçacıklar daha sonra bir araya gelerek atomu oluşturmuşlardır. Big Bang absolü sıfırın hükmettiği bir hiçlik içinde vuku bulmuştur.

İçinde yaşadığımız evrende absolü sıfıra ulaşmak mümkün değildir. Çünkü madde buna olanak vermeyecektir.

İlginç olarak laboratuvarda absolü sıfırın bir derecenin milyarda biri kadar yaklaşildığı halde, absolü sıfıra ulaşmak mümkün olamamaktadır. Işık hızının bir limiti olduğu gibi, doğa temperatürün alt sınırına bir sınır koymuştur. Temparatürün üst sınırı limitsizdir. Işığın da alt sınırı limitsizdir. Işık durdururabilir. Ama ne temperatür absolü sıfır olan -273,15 derecenin altına inebilir, ne de ışık hızı saniyede 300 bin km'nin üstüne çıkabilir.

Kuralları ve yasaları olan bir evrende yaşamaktayız. Onların ihlal edildiği şimdiye kadar gözlemlenmemiştir.

Absolü sıfırın altına inilmiş midir?

[Mesudi 0]

Ama ne temperatür absolü sıfır olan -273,15 derecenin altına inebilir, ne de ışık hızı saniyede 300 bin km'nin üstüne çıkabilir.

Kuralları ve yasaları olan bir evrende yaşamaktayız. Onların ihlal edildiği şimdiye kadar gözlemlenmemiştir.

Absolü sıfırın altına inilmiş midir?

Sn Hacı bey bilgiler için teşekkür ediyorum.Bir bilim insanı değilim, verdiğiniz değerlerin hangi anlamlara geldiğini bilmiyorum.

Ancak bilim dünyasını sıkı takip eden bir birey olarak, "Olanaksız" ifadesinin bilim dünyasında bir değeri olmadığını görüyorum.

Geçmiş dönemlerde bilinemeyenleri bu gün bilen, geçmiş dönemlerde yapılamayanları, bu gün yapan bir türün bireyi olarak gelecekle ilgili byüük gelişmelerin yaşanacağını ön görebiliyorum.

Her ne kadar Spekülatif cümleler kursamda, mevcut bilimsel keşiflerin, bilim kurgu tadındaki bu spekülatif düşünceleri başarabileceği yönünde umut taşımaktayım.

Verdiğiniz bilgiler için tekrar teşekkür ediyorum.

[CinciHoca 0]

Sn Hacı bey bilgiler için teşekkür ediyorum.Bir bilim insanı değilim, verdiğiniz değerlerin hangi anlamlara geldiğini bilmiyorum.

Ancak bilim dünyasını sıkı takip eden bir birey olarak, "Olanaksız" ifadesinin bilim dünyasında bir değeri olmadığını görüyorum.

Geçmiş dönemlerde bilinemeyenleri bu gün bilen, geçmiş dönemlerde yapılamayanları, bu gün yapan bir türün bireyi olarak gelecekle ilgili byüük gelişmelerin yaşanacağını ön görebiliyorum.

Orası öyle de geçmişte bu yapılamaz, bu bilinemez diyenler dinci tayfasıydı.

Bana da olanaksız gibi geliyor. Hacimsiz bir şeyin olması mümkün değil gibi..

Ama mümkün olduğunu kanıtlayan bir formül falan ortaya koysunlar.

Biz de olur diyelim..

[haci 0]

Host – Kerry Klein

Imagine what it would feel like to touch the Sun, which—as far as the human experience

is concerned—is essentially infinitely hot. But what if I were to tell you that some

materials can reach temperatures that are hotter than infinitely hot? And what if I were to

tell you that those temperatures are below zero Kelvin? Ulrich Schneider, author of a

Report this week, spoke with me about the mathematical and physical reality of negative

absolute temperatures—and why they’re important for physics and cosmology.

Interviewee – Ulrich Schneider

This research is basically about extending temperature. You all know temperature

ranges. You all know the ordinary temperature, the Celsius scale – you can have positive

numbers, negative numbers – but you also know that there’s the absolute temperature

scale, the Kelvin scale, where you normally only have positive numbers. It’s thought that

zero can go up all the way to infinity, but that’s it. Well, it’s not. In some sense what

we’re doing is we’re extending this to negative absolute temperatures. And the important

thing to remember right away is that this is not colder than zero Kelvin – nothing can be

colder than that – but it’s actually the opposite. It’s even hotter than infinite

temperatures. This is kind of a pretty old and classical problem, so it’s nothing to do with

quantum mechanics. But it’s just when you look at the formulas describing temperature,

you really see that the scale starts at zero, it increases up to infinity, but it doesn’t

necessarily stop there. In fact, what we see is that it jumps from plus infinity to minus

infinity, and then continues growing. So the energy of the system grows forever and

forever and forever until it reaches zero again from below.

Interviewer – Kerry Klein

Okay. So let’s start with the basics of absolute temperature. Like you said, with the

Celsius and Fahrenheit scales, temperature can be both positive and negative. But with

the Kelvin scale, which we refer to as absolute temperature, zero is considered basically

the lowest temperature possible. So how exactly is this property defined? What’s

actually happening at the molecular level to yield an absolute temperature?

Interviewee – Ulrich Schneider

What’s happening is actually that absolute temperature is directly connected, it’s in fact

directly proportional to the average kinetic energy of the particles. So it’s proportional to

how fast the particles move. So if you think of a classical gas like little balls flying

around you, like the air around you, then actually absolute temperature is a measure on

how fast these particles move on average, how high their kinetic energy is. The hotter

they are, the faster they move. Therefore, it kind of makes sense that there should be an

absolute lower limit, because at some point the particles will all be at rest, they won’t

move at all. And, obviously, they can’t be slower than not moving at all, so therefore

nothing can be colder than zero Kelvin.

Interviewer – Kerry Klein

And so how, then, can we get a negative absolute temperature? How is that possible?

Interviewee – Ulrich Schneider

Well, the point is if you now get a little bit more mathematical and think about the

distribution of these energies. When you have a positive temperature, you have

something that’s described by the so-called Boltzmann distribution – that’s just the name

– but it basically just means that at a positive temperature, the atoms have different

velocities. Some atoms move fast, some atoms move slow. And when you have a

positive temperature, it means that the low energy states, they’re more occupied than

your high energy states. When you think of the ground state of zero Kelvin, then only the

lowest energy states are occupied, meaning for our moving particles, they all stand still,

and your higher ones are absolutely not occupied. If you now increase temperature, you

put energy into the system, more and more states become occupied, even the higher

energy ones, and this distribution – this Boltzmann distribution – becomes more and

more flat. And actually at infinite temperature, it becomes completely flat. All states

have the same probability of being occupied, whether they have low energies or high

energies. And now you can directly think of how to extend this. What would happen if

you now have more particles at high energies than at low energies? And that’s actually

what you would get if you would take the same formulas and would put in a negative

temperature. Another very intuitive model to think about those negative temperatures is

to think about a set of balls – normal classical balls – in an environment with a hill and a

valley. The higher up the hill the balls slide, the higher their potential energy is. At a

positive temperature you would say normally you put some hills in the valleys and they

sit there stable. And now you can take the system as a whole, shake it a little bit, and

they will remain in the valley because that’s where they are stable. And that’s another

positive temperature ensemble. And now with negative temperatures, that means that

you put atoms on the top of the hills which are already moving with the maximum

possible kinetic energy. And now it’s a very funny thing that happens. If you now shake

this whole system, the balls will stay on top of the hill.

Interviewer – Kerry Klein

And that’s the high energy state.

Interviewee – Ulrich Schneider

And that’s the high energy state. Exactly. And the reason for this is that as they already

have close to the maximum kinetic energy, they cannot increase it. So they cannot roll

down the hill, because the potential energy has nowhere to go. Energy is conserved. It

should go into kinetic energy, but as the kinetic energy is already at its maximum, they

can’t. So that’s why the balls have no chance, they have to stay on top of the hill. And

that’s why negative temperature states are stable.

Interviewer – Kerry Klein

So you explain this mathematically, but how does one actually create a system – how did

you actually create a system that is physically at a negative absolute temperature?

Interviewee – Ulrich Schneider

Well, what we do in the lab is we use the techniques that have been developed in the

context of ultracold atoms. So the first thing we do, surprisingly, is we have to cool

down the atoms a lot to like a billionth of a Kelvin or something – very, very cold

temperatures – and then we put them into an optical lattice, and then they all occupy just

this lowest band of this lattice. This has been used for the last 10 years to do many

interesting many-bodied physics. One famous example that we’re actually building upon

is the creation of a so-called Mott insulator. That’s the creation of an insulating state

where the particles are evenly distributed over the lattice with one particle – exactly one

particle – per lattice site. And in this state, the particles are kind of frozen out; they

cannot move anymore. The reason for this is that these particles repel each other. They

have a repulsive interaction. And then if two particles would meet on the same lattice

side, then they would increase their energy. They would have to pay a lot of interaction

energy, and therefore they don’t do it. So we now have this state. We’ve frozen out

particles – exactly one particle per lattice site. And the new trick, the new feature what

we now do is we changed interactions from repulsive to attractive. So now the particles

would love to sit under the same lattice side, because they would gain a lot of energy by

doing so. But the state in which we have created this is a state with exactly one atom per

lattice site, which means they never meet. And if we now unfreeze them, if we now

lower the lattice again so that they can start to move again, they realize that they are now

in the highest possible energy state of the system. And then it’s natural for them to

really, like, thermalize into a thermal distribution, but into a thermal distribution with

negative energy. So in a nutshell, the key points are you need to have a system where

you have an upper bound in energy. Then you have to create your system very close to

this bound, that you have a very, very high energy per particle, and then you just have to

wait. Then the system naturally thermalizes into such a negative temperature ensemble.

Interviewer – Kerry Klein

And what kind of atoms were you using for this experiment?

Interviewee – Ulrich Schneider

In this case we were using ultracold potassium atoms, but that’s actually mostly a

technicality. We were using them because they do allow us very easily to switch the

interaction from repulsive to attractive.

Interviewer – Kerry Klein

So how stable is a system at negative absolute temperature? You know, you created your

system in a protected vacuum environment in a lab, but can negative absolute

temperature materials actually exist naturally?

Interviewee – Ulrich Schneider

We can also create positive temperature systems in our experiment, and we see that the

positive and negative systems have the same stability. Our negative temperature systems

are as stable as our positive temperature systems. You know if you bring one very hot

and one very cold positive temperature system in formal contact, then what you get is you

get one big system at a kind of intermediate temperature. So if you would now take

several systems at several negative temperatures, they would also equilibrate in the same

way to some average negative absolute temperature. The point that we have to so well

isolate them from their environment is only that the environment that we have locally

here around us is a positive temperature environment. It’s maybe a little bit the same as

with antimatter. You know, you mix different kinds of matter, they are stable. You mix

different kinds of antimatter, they are as stable. But if you bring matter and antimatter

together, then something happens. It’s kind of similar here.

Interviewer – Kerry Klein

So how does this research advance your field? What’s the greater significance of this

work?

Interviewee – Ulrich Schneider

Well, let me answer this in two ways. Number one is the very practical engineering

approach, and that is that for us this is a new tool which really enhances the parameter

space that we can probe. We have probed so far these ultracold atom systems and optical

lattices at positive temperatures, and we have already learned a lot about things related to

solid-state physics, to how electrons behave in certain types of solids, but there is many,

many more things to learn. There is also many more things that we can’t access right

now. And by now using negative temperature systems instead of positive temperature

systems, we’re kind of probing the high energy regime instead of the low energy regime,

and we can, therefore, increase the range of effects that we can describe, that we can

probe, that we can understand in the lab. I would say the stronger point for this work is

more that on a conceptual point-of-view, it enhances our way of thinking about

thermodynamics. When you say something gets hotter, there’s a little bit of confusion in

there because you can mean two things. It can mean, on the one hand, that you increase

the energy of your system. It can also, on the other hand, mean that you increase the

disorder of your system, because in the positive temperatures, that both things go handin-

hand. You increase the energy of your system, you also increase the disorder of your

system. But now at negative temperatures, this turns around. If you increase the energy

in the system, you decrease the disorder. The system becomes more ordered. So at

negative temperatures, the connection between entropy and energy is kind of reversed.

And it’s a very interesting fact to think about, and it helps you to think about several

aspects in a new way. So that’s kind of the conceptual point-of-view. If you now again

look into the mathematics, you realize from thermodynamic relations that at negative

temperatures, only negative pressures can be stable. So we realize negative pressures in

the lab. And cosmology also use dark energy, which they say is a solution for negative

pressure to describe this accelerated expansion of the universe.

Interviewer – Kerry Klein

Right.

Interviewee – Ulrich Schneider

And it will be interesting to see whether you can get something out of this resemblance, if

we can use this to understand anything better, or whether it’s just a curiosity.

Interviewer – Kerry Klein

Great. Ulrich Schneider, thank you so much.

Interviewee – Ulrich Schneider

You’re welcome.

Host – Kerry Klein

Ulrich Schneider and colleagues write about attaining negative absolute temperatures in a

Report this week.

[Doga_Bilim 0]

Mutlak sıfırın kaç kelvin altına inmişler?

Mutlak sıfırın altında sıcaklığı neye göre ölçüyorlar?

[ehl-i dünya 0]

mutlak sıfır, adı üzerinde mutlaktır.

ısı maddelerin iç enerjilerinin bir sonucudur. bu iç enerjisini atomların öteleme, dönme, titreşim kinetik enerjileri ve elektrostatik çekim kuvvetleri gibi potansiyel enerjileri oluşturur. ısı, sıcaklık farkından dolayı iletilen bir enerji biçimidir. sıcaklık ise termal hareketin sonucudur.

kısacası, mutlak sıfırda atom titreşmez, içine çöker. bu ilkten akla gelen inşaatın çökmesi gibi değil tabii ki. kendine özgü mekanizma ile. madde meydana gelemez.

şu an burada yazışıyorsan, mutlak sıfır'ın üstündeyiz demektir. ancak evrende entropi sürekli artar ve minimum enerjiye geçiş olur. big crunch teorisine göre evren gelecekte çökecek. gelecek derken yine insanın hayali almayacak uzun bir zaman.

cahil cahil başlık açmayız.

[nemesis_ 0]

http://www.nature.co...te-zero-1.12146

Youtube'da da bazı kanallarda rastlamıştım. Minutephysics ve sixty symbols gibi..

Düzenli titreşen kuantum sistemlerimiymiş neymiş ben pek anlamadım ama var yani. Biraz sıcaklığın tanımının dışında kullanılıyor.

---

Biraz daha baktım.

Şöyle koca bir şey buldum. Yani bizim kelvin değerinin mutlak değeri taneciklerin titreşim gücünü gösteriyor. Negatif kelvin, 0'dan daha sıcak imiş.

Açıklaması da şöyle:

Hot minus temperatures: At a negative absolute temperature the energy distribution of particles inverts in comparison to a positive temperature. Many particles then have a high energy and few a low one. This corresponds to a temperature which is hotter than one that is infinitely high, where the particles are distributed equally over all energies. A negative Kelvin temperature can only be achieved experimentally if the energy has an upper limit, just as non-moving particles form a lower limit for the kinetic energy at positive temperatures –physicists at the LMU and the Max Planck Institute of Quantum Optics have now achieved this.

Mayıs 20, 2014 tarihinde nemesis_ tarafından düzenlendi