Can absolute zero ever be achieved?

In summary, the concept of absolute zero, which is the theoretical lack of energy, is impossible to attain in practical terms. This is because a perfect insulator, which is necessary for reaching absolute zero, does not exist. The Third Law of Thermodynamics states that absolute zero is unattainable, and our current technology is not advanced enough to achieve it. Even if absolute zero were to be reached, it would violate the Heisenberg Uncertainty Principle and lead to the cooling of other substances in the universe. Additionally, the existence of photons and their minimum energy levels would prevent the attainment of absolute zero. Overall, while there have been attempts to reach absolute zero, it remains an unattainable concept in our
  • #1
ffleming7
25
0
Can absolute zero ever be achieved? I this a theoretical kinetic energy?
 
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  • #2
It's more a theoretical lack of energy. Although we've come very close to it with liquid helium, I don't think that it's practically attainable. You would need, to start with, a perfect insulator, which doesn't exist.
 
  • #3
Isn't the point of the third law of thermodynamics that it is impossible to reach absolute zero?
 
  • #4
nicksauce said:
Isn't the point of the third law of thermodynamics that it is impossible to reach absolute zero?

Correct, at least the way that I learned the 4 laws.
1) No matter how hard you try, the best that you can do is break even.
2) You can only break even at absolute zero.
3) Absolute zero is impossible to attain.
4) No matter how hard you shake it, the last drop always goes down your pants.
 
  • #5
Danger said:
Correct, at least the way that I learned the 4 laws.
1) No matter how hard you try, the best that you can do is break even.
2) You can only break even at absolute zero.
3) Absolute zero is impossible to attain.
4) No matter how hard you shake it, the last drop always goes down your pants.

Number 4... ROFL
 
  • #6
Danger said:
Correct, at least the way that I learned the 4 laws.
1) No matter how hard you try, the best that you can do is break even.
2) You can only break even at absolute zero.
3) Absolute zero is impossible to attain.
4) No matter how hard you shake it, the last drop always goes down your pants.


I hate that SO much. :grumpy:

If absolute zero is impossible to attain, then is it not found anywhere in the universe? Is it something that just cannot be broken, in terms of going any lower?
 
  • #7
if absolute zero is obtained the universe will collapse into itself...
 
  • #8
I'm not so sure about the collapsing part, but the universe as a whole is still permeated by the cosmic microwave backgound 'noise' from the Big Bang. That's something like 3 degrees K.. To attain absolute zero, you'd have to isolate a container of some type, and then pump out those 3 degrees. I'm not saying categorically that it's impossible, because technology continues to take me by surprise, but our current methods aren't up to it.
 
  • #9
nightshade123 said:
if absolute zero is obtained the universe will collapse into itself...

Erm...why?
 
  • #10
Danger said:
I'm not so sure about the collapsing part, but the universe as a whole is still permeated by the cosmic microwave backgound 'noise' from the Big Bang. That's something like 3 degrees K.. To attain absolute zero, you'd have to isolate a container of some type, and then pump out those 3 degrees. I'm not saying categorically that it's impossible, because technology continues to take me by surprise, but our current methods aren't up to it.


You would also need to have perfect insulation would you not?
 
  • #11
As mentioned in post #2, yes. I don't believe (just my opinion) that there can be such a thing, given quantum fluctuations and whatnot.
 
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  • #12
I don't remember the the Laws of Thermodynamics forbidding absolute zero, but either way it's still impossible to attain absolute zero. To do so would be in violation of the Heisenberg Uncertainty Principle as if a particle is at absolute zero you would be able to learn it's precise position and velocity.
 
  • #13
I never thought of it that way, but it makes sense. Its energy and movement would both be '0'.
 
  • #14
and if u get particles to stop moving what do you thing will happen to everything around it...
 
  • #15
Not much.
 
  • #16
Really in order for absolute zero to be achieved, which it isn't but hypothetically here, the matter being put at absolute zero would have to be secluded from all other matter and shielded from radiation. Even if it wasn't it just means that you'll start slowly cooling other stuff too.
 
  • #17
PiratePhysicist said:
Even if it wasn't it just means that you'll start slowly cooling other stuff too.

Bingo! And by cooling other stuff, you're gaining heat from it.
 
  • #18
Therefore it's impossible to reach absolute zero until all atomic motion in the system (universe) has been stopped.

As has been said before, perfect insulators don't exist. If one atom isn't moving and there's an atom that is moving near it, the one that isn't moving will steal some of the energy from the moving atom and start to move.
 
  • #19
It's fundamentally impossible to get any part of the universe to reach absolute zero, the part about needing the insulation was just a matter of hypothetical thinking.
 
  • #20
Theoretically? Yes you can reach it if you have a perfect insulator (which is impossible)

and because there does not exist a perfect insulator in the universe, as long as there is heat somewhere in the universe, its not possible. Besides, the moment you try to measure it to make sure all motion has stopped, you will have inadvertently heated it back up again. You'd be stuck with a container that you cannot touch, pointing at it and screaming eureka with absolutely no way to prove there's anything inside to begin with
 
  • #21
Photons have a spin of one, as electrons and protons have a spin of one-half; these quantum phenomena no amount of cooling can extinguish. I think it safe to assume that these residual spins involve a minimum energy (and thus temperature) greater than zero. My guess is that although absolute zero may exist at certain singularities, the very attempt to measure it would cause heating.
 
  • #22
Having used vortex tube coolers, and finding a refrigeration manuel that explained in detail how they work, my question is, would the very center of a vortex of high velocity produce a very small center point of zero condition ?
 
  • #23
My chemistry teacher said that some institute came very close to reaching absolute zero...but all the same, it will be impossible to ever attain absolute zero.
 
  • #24
I really think that it's time for one of the 'gurus' to get involved. Someone with professional knowledge such as Zapper Z, Arildno, or Astronuc can probably put this thing to bed without us having to speculate further.
 
  • #25
Danger said:
I really think that it's time for one of the 'gurus' to get involved. Someone with professional knowledge such as Zapper Z or Astronuc can probably put this thing to bed without us having to speculate further.
Post edited appropriately. :smile:
 
  • #26
You silly ass. :rofl:
Even if it's not your particular field of research, you still know a hell of a lot more about this stuff than we do.
 
  • #27
RonL said:
Having used vortex tube coolers, and finding a refrigeration manuel that explained in detail how they work, my question is, would the very center of a vortex of high velocity produce a very small center point of zero condition ?

Nope, energy from the outside system would cause the center to have energy, albeit a very small amount.

Absolute zero is only possible if we have either a perfect insulator, or all atomic motion in the universe stops, both of which I don't see happening any time soon.
 
  • #28
The PBS.ORG just aired a 2 part document " in search of absolute zero"

http://www.pbs.org/wgbh/nova/zero/

If i rember right, a temp of less than one degree was reached by MIT.
A good artical to look at for anyone interested.

Go to chapter 10 for the coldest temp recorded.
 
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  • #29
PiratePhysicist said:
I don't remember the the Laws of Thermodynamics forbidding absolute zero, but either way it's still impossible to attain absolute zero. To do so would be in violation of the Heisenberg Uncertainty Principle as if a particle is at absolute zero you would be able to learn it's precise position and velocity.

Well, it would be a violation of the Heisenberg uncertainty principle if you could detect the existence of such a particle. I don't see how its sole existence would violate it.

Also, thermodynamics seems to be a field of probability. While energy tends to flow from high to low on average, there are cases where by pure chance energy will flow in the opposite direction. Perhaps with the enormous number of particles in the universe, one has been just lucky enough to lose all its energy.
 
  • #30
greeniguana00 said:
Well, it would be a violation of the Heisenberg uncertainty principle if you could detect the existence of such a particle. I don't see how its sole existence would violate it.

Not quite. The problem is that "temperature" is a very tricky concept to define but according to the "normal" statistical way of doing it (modelling the environment as a bath of oscillators) the result is that particles will still move -albeit very slowly- at 0K due to quantum brownian motion.
However, we run into problems with temperature much earlier than this. The lowest fixed point on the international temperatures scale (ITS-90) is as high as 650mK, one reason being that once we go much below that the concept of temperature becomes very fuzzy, it is simply difficult to define it in a meaningfull way (I know a few people that work in cryogenic thermometry).
650 mK is actually a fairly high temperature so this causes some practical problems, e.g. a normal -relatively cheap- He-3 system can easily reach a temperature of about 270 mK. Dilution fridges can go to about about 10 mK (without wiring, in use most fridges have a base temperature of 20-25 mK). Hence, we routinely reach temperatures much lower than this in the lab (not counting optical cooling of gases ,where "temperatures" of nK are often recorded, but in this case the temperature is just a measure of the average kinetic energy for a relatively small number of atoms.)
Note that when I write "reach" I mean that this is the temperature indicated by the temperature sensors (e.g. ohmic sensors like RuO2 or nuclear orientation thermometers), but this does not mean that it is the "physical" temperature of the system being probed in the experiment , that temperature can be much higher (a point which is often overlooked by people without enough experience).
 
  • #31
ffleming7 said:
Can absolute zero ever be achieved? I this a theoretical kinetic energy?


Yes, absolute zero can be reached, although not using thermodynamical means. And no, temperature is not kinetic energy, despite what most high school physics textbooks will tell you.

Temperature is a statistical concept that arises when you describe a system consisting of many particles using a few macroscopically measurable variables like volume, pressure etc. Clearly, to be able to do statistical computations, you need to know the probabilities of the system being in some arbitrary state. It turns out that for an isolated system the laws of physics suggest that all accessible states are a priori equally likely. So, it's a bit like throwing dice, all the possible throws are equally likely. And just like dice throwing problems can be solved by counting in how many ways a certain outcomes can be realized, in physics we just neet to know how many states there are for each macrostate. I.e. given the volume, total internal energy, how many energy levels are there compatible with these macroscopic variables? All these energy levels the system can be in are then equally probable.

A minor complication is the following. If we specify the internal energy with infinite accuracy, then there usually can be only one state the system can be in (ignoring possible exact degeneracies). If the system consists of a large number of particles, then the spacing between energy levels will decrease (simply because the more particles you have, the more different states between two given total energies you can make). So, what we do is we specify a small energy interval [tex]\Delta E[/tex] and when we say that the total energy is [tex]E[/tex] we mean that the system must be in some energy level with an energy between [tex]E[/tex] and [tex]E+\Delta E[/tex]. It turns out that the choice of [tex]\Delta E[/tex] does not affect the outcome of calculations when the limit of system size to inifinity is taken (the so-called thermodynamic limit).

What we need to know to do statistics is, given some energy [tex]E[/tex], how many states (energy levels) are there between energy [tex]E[/tex] and [tex]E+\Delta E[/tex]? It is customary to denote this quantity (so-called multiplicity fiunction) as [tex]\Omega\left(E\right)[/tex].

To see how all this leads to something like "temperature", consider two systems with multiplicity functions [tex]\Omega_{1}\left(E_{1}\right)[/tex] and [tex]\Omega_{2}\left(E_{2}\right)[/tex]. The number of states available for the combined system must be the product:

[tex]\Omega_{1}\left(E_{1}\right)\times \Omega_{2}\left(E_{2}\right)[/tex]

Suppose that we bring the two systems into contact, so that energy can flow from one system to the other. If all microstates are equally likely, then in thermal equilibrium, you will get that outcome for which there are the largest number of microstates. If the total energy is [tex]E[/tex], then we can put [tex]E_{2}=E - E_{1}[/tex] and compute for which value for [tex]E1[/tex] the above expression is maximal. It is more convenient to maximize the logarithm:



[tex]\frac{d \log\left[\Omega_1\left(E_1\right)\right]}{dE_1} = - \frac{d \log\left[\Omega_2\left(E-E_1\right)\right]}{dE_1} [/tex]

Or, rewriting the r.h.s. in terms of [tex]E_2[/tex]:


[tex]\frac{d \log\left[\Omega_1\left(E_1\right)\right]}{dE_1} = \frac{d \log\left[\Omega_2\left(E_2\right)\right]}{dE_2} [/tex]

So, what we see is that the derivatives of the logarithms of the multiplicity functions w.r.t. energy become equal in thermal equilibrium. One defines the temperature as being inversely proportional to this quantity.


Now, with a little more work you can show that at zero temperature a system will be in the ground state. So, the question is really, can we put a system in its ground state? The answer is, of course we can! In principle, even for a system containing [tex]10^{30}[/tex] particles, you can put the entire system in its ground state simply by manipulating the individual particles. Quantum mechanics will not prevent you from doing that.

However, you cannot do it using thermodynamic means only (i.e. by manipulating the few macroscopic variables or by bringing the system into thermal contact with another system). The reason is that thermal contact does not work because heat flows only from hot to cold, so you would need something colder in the first place. The only other option left is by letting the system perform work. But this will leave the multiplicity function [tex]\Omega[/tex] the same at best. Going to lower [tex]\Omega[/tex] is statistically ruled out because all states being equally likely, lower [tex]\Omega[/tex] has less probability. Now, a little less proabability would be no problem, however, at absolute zero the system has [tex]\Omega=1[/tex] because we then know it to be in the (unique) ground state. The system at even very low but nonzero temperatures will have an astronomically large value for [tex]\Omega[/tex].
 
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  • #32
Great post Count Iblis! I agree with what you are saying.
 
  • #33
greeniguana00 said:
Well, it would be a violation of the Heisenberg uncertainty principle if you could detect the existence of such a particle. I don't see how its sole existence would violate it.

Also, thermodynamics seems to be a field of probability. While energy tends to flow from high to low on average, there are cases where by pure chance energy will flow in the opposite direction. Perhaps with the enormous number of particles in the universe, one has been just lucky enough to lose all its energy.
Isn't the definition of absolute zero when an ideal gas exerts zero pressure and so the temperature is derived indirectly and so would not be a violation of Heisenberg's uncertainty principle ?

Also AFAIK a gas at absolute zero still has quantum fluctuations. Isn't this motion the source of zero point energy?
 
  • #34
One thing I never understood about absolute zero or even near it. Say you had a gas that was near abs zero. Since the particles are moving so slow wouldn't they be closer to the ground to a point that the gas is just a pile of single atoms on the floor? Considering that there is not energy for the gas to rise.
 
  • #35
bassplayer142 said:
One thing I never understood about absolute zero or even near it. Say you had a gas that was near abs zero. Since the particles are moving so slow wouldn't they be closer to the ground to a point that the gas is just a pile of single atoms on the floor? Considering that there is not energy for the gas to rise.

Bose-Einstein condensates. Google.
 
<h2>1. What is absolute zero?</h2><p>Absolute zero is the theoretical temperature at which all thermal motion stops and a substance has no heat energy.</p><h2>2. Can absolute zero be achieved?</h2><p>No, it is impossible to reach absolute zero as it is a theoretical concept and cannot be achieved in practice.</p><h2>3. What is the coldest temperature that has been achieved?</h2><p>The coldest temperature ever achieved is 100 picokelvins, which is only a fraction of a degree above absolute zero.</p><h2>4. Why is it impossible to reach absolute zero?</h2><p>According to the Third Law of Thermodynamics, it is impossible to reach absolute zero because it would require a perfect crystalline structure with zero entropy, which is not possible in reality.</p><h2>5. What happens to matter at absolute zero?</h2><p>At absolute zero, all molecular motion stops and matter becomes completely rigid. This is known as the Bose-Einstein condensate state.</p>

1. What is absolute zero?

Absolute zero is the theoretical temperature at which all thermal motion stops and a substance has no heat energy.

2. Can absolute zero be achieved?

No, it is impossible to reach absolute zero as it is a theoretical concept and cannot be achieved in practice.

3. What is the coldest temperature that has been achieved?

The coldest temperature ever achieved is 100 picokelvins, which is only a fraction of a degree above absolute zero.

4. Why is it impossible to reach absolute zero?

According to the Third Law of Thermodynamics, it is impossible to reach absolute zero because it would require a perfect crystalline structure with zero entropy, which is not possible in reality.

5. What happens to matter at absolute zero?

At absolute zero, all molecular motion stops and matter becomes completely rigid. This is known as the Bose-Einstein condensate state.

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