When something is cooled to absolute zero...

[KIAman]

does the item disappear from the universe? Assuming all motion stop including quantum.

This has been boggling my mind for the last several months. Is this why nothing can reach absolute zero because of conservation of energy?

 

[f95toli]

Why would it disappear

There is nothing "special" about absolute zero in this respect, remember that we use models where we assume the temperature to be zero all the time (just to simplify the equations).

The reason you can't reach absolute zero is more or less the same reason an exponentional function never goes to zero (unless you let it go to infinity); you can get arbitrariy close but as long as there is ANY energy left it would not be zero; would it?
Also, things would still move even at absolute zero; if ones uses the usual defintion of temperature one finds that the particles would move due to quantum effects even at 0K.

It is perhaps worth pointing out that whereas we can reach absolute zero we can get pretty close: we cool even large objects (and I do mean large, several kg) down to below 0.001 K (and below 50 mK has been routine for many years) and gases can be cooled much lower than that (laser cooling etc).
Hence, there are many situations even in real experiments where for all intensts and purposes the temperature is zero.

 

[bsobel]

Originally posted by: KIAman
does the item disappear from the universe? Assuming all motion stop including quantum.
This has been boggling my mind for the last several months. Is this why nothing can reach absolute zero because of conservation of energy?

Well, its a thought expirement so you can come up with whatever answers you like... But in some quantum models, yes matter disappears since 'matter' is just a collection of vibrating strings and if the strings aren't vibarting then 'poof'....

That said even at 0k the item is still effected by zero-point energy, so it's never 'truely' at rest...

 

[Dominato3r]

When An atom reaches absolute zero it freezes in place including air. Solids might freeze a bit earlier but i dont know that for sure

 

[Born2bwire]

Originally posted by: bsobel

Originally posted by: KIAman
does the item disappear from the universe? Assuming all motion stop including quantum.
This has been boggling my mind for the last several months. Is this why nothing can reach absolute zero because of conservation of energy?

That said even at 0k the item is still effected by zero-point energy, so it's never 'truely' at rest...

Interaction with the vacuum fluctuation will not affect it. You may get a momentary force that will move a part of the object but eventually a counteracting force will achieve equilibrium.

 

[silverpig]

Originally posted by: f95toli
Why would it disappear

There is nothing "special" about absolute zero in this respect, remember that we use models where we assume the temperature to be zero all the time (just to simplify the equations).

The reason you can't reach absolute zero is more or less the same reason an exponentional function never goes to zero (unless you let it go to infinity); you can get arbitrariy close but as long as there is ANY energy left it would not be zero; would it?
Also, things would still move even at absolute zero; if ones uses the usual defintion of temperature one finds that the particles would move due to quantum effects even at 0K.

It is perhaps worth pointing out that whereas we can reach absolute zero we can get pretty close: we cool even large objects (and I do mean large, several kg) down to below 0.001 K (and below 50 mK has been routine for many years) and gases can be cooled much lower than that (laser cooling etc).
Hence, there are many situations even in real experiments where for all intensts and purposes the temperature is zero.

I think he's talking about the uncertainty principle. If you make the momentum 0 and know it precisely, then the position could be anywhere in the universe... sorta.

 

[bsobel]

Interaction with the vacuum fluctuation will not affect it. You may get a momentary force that will move a part of the object but eventually a counteracting force will achieve equilibrium.

The point being is that the molecular motion doesnt not actualy stop if you could reach 0K, zpe actually prevents this. This negates the therotecial would the matter 'disappear' question if matter is indeed built of vibrating strings, enough vibrations continue due to ZPE to prevent the scenario the OP asked about.

 

[Born2bwire]

Originally posted by: bsobel

Interaction with the vacuum fluctuation will not affect it. You may get a momentary force that will move a part of the object but eventually a counteracting force will achieve equilibrium.

The point being is that the molecular motion doesnt not actualy stop if you could reach 0K, zpe actually prevents this. This negates the therotecial would the matter 'disappear' question if matter is indeed built of vibrating strings, enough vibrations continue due to ZPE to prevent the scenario the OP asked about.

Casimir force isn't a random force though. The vacuum fluctuation has discrete energy levels, you're not going to get random motion from them, especially since we can't extract energy from vacuum fluctuations. There will be a set of forces on the atoms and structure of the object, but it will become a static force once the object's own intermolecular forces bring the system into equilibrium.

 

[bsobel]

Casimir force isn't a random force though. The vacuum fluctuation has discrete energy levels, you're not going to get random motion from them, especially since we can't extract energy from vacuum fluctuations. There will be a set of forces on the atoms and structure of the object, but it will become a static force once the object's own intermolecular forces bring the system into equilibrium.

The point simply is you get enough motion from them so that the matter is not at rest and the uncertainty principal isn't violated.

 

[Born2bwire]

Originally posted by: bsobel

Casimir force isn't a random force though. The vacuum fluctuation has discrete energy levels, you're not going to get random motion from them, especially since we can't extract energy from vacuum fluctuations. There will be a set of forces on the atoms and structure of the object, but it will become a static force once the object's own intermolecular forces bring the system into equilibrium.

The point simply is you get enough motion from them so that the matter is not at rest and the uncertainty principal isn't violated.

But you can't get it to do work, you can't extract more energy from vacuum fluctuations than you took out of it. If I have a cantilever MEMS switch, there is an attractive force between the lever and the base plate due to vacuum fluctuations from the change in the vacuum energy between when there was no matter and when we placed the switch into the vacuum. If we have a 0K temperature bath, then random motion of the molecules stop. If the Casimir force pulls on the switch in an oscillatory manner, causing it to vibrate, then we have to be extracting energy from the vacuum due to inherent damping and friction in the system. This we cannot do, at best there will be a constaint static force on the lever or it will be strong enough to close the switch but eventually it will reach some equilibrium state.

Plus, the uncertainty principle only comes into concerning measurements. We can have a system that actually has say zero kinetic energy without violating the uncertainty principle. The uncertainty principle only limits the degree of precision in how we measure the system between non-commutable observables.

 

[bsobel]

Originally posted by: Born2bwire

Originally posted by: bsobel

Casimir force isn't a random force though. The vacuum fluctuation has discrete energy levels, you're not going to get random motion from them, especially since we can't extract energy from vacuum fluctuations. There will be a set of forces on the atoms and structure of the object, but it will become a static force once the object's own intermolecular forces bring the system into equilibrium.

The point simply is you get enough motion from them so that the matter is not at rest and the uncertainty principal isn't violated.

But you can't get it to do work, you can't extract more energy from vacuum fluctuations than you took out of it. If I have a cantilever MEMS switch, there is an attractive force between the lever and the base plate due to vacuum fluctuations from the change in the vacuum energy between when there was no matter and when we placed the switch into the vacuum. If we have a 0K temperature bath, then random motion of the molecules stop. If the Casimir force pulls on the switch in an oscillatory manner, causing it to vibrate, then we have to be extracting energy from the vacuum due to inherent damping and friction in the system. This we cannot do, at best there will be a constaint static force on the lever or it will be strong enough to close the switch but eventually it will reach some equilibrium state.

Plus, the uncertainty principle only comes into concerning measurements. We can have a system that actually has say zero kinetic energy without violating the uncertainty principle. The uncertainty principle only limits the degree of precision in how we measure the system between non-commutable observables.

http://www.calphysics.org/zpe.html

"In conventional quantum physics, the origin of zero-point energy is the Heisenberg uncertainty principle, which states that, for a moving particle such as an electron, the more precisely one measures the position, the less exact the best possible measurement of its momentum (mass times velocity), and vice versa. The least possible uncertainty of position times momentum is specified by Planck's constant, h. A parallel uncertainty exists between measurements involving time and energy (and other so-called conjugate variables in quantum mechanics). This minimum uncertainty is not due to any correctable flaws in measurement, but rather reflects an intrinsic quantum fuzziness in the very nature of energy and matter springing from the wave nature of the various quantum fields. This leads to the concept of zero-point energy."

"Zero-point energy is the energy that remains when all other energy is removed from a system. This behaviour is demonstrated by, for example, liquid helium. As the temperature is lowered to absolute zero, helium remains a liquid, rather than freezing to a solid, owing to the irremovable zero-point energy of its atomic motions"

 

[Born2bwire]

Originally posted by: bsobel

Originally posted by: Born2bwire

Originally posted by: bsobel

Casimir force isn't a random force though. The vacuum fluctuation has discrete energy levels, you're not going to get random motion from them, especially since we can't extract energy from vacuum fluctuations. There will be a set of forces on the atoms and structure of the object, but it will become a static force once the object's own intermolecular forces bring the system into equilibrium.

The point simply is you get enough motion from them so that the matter is not at rest and the uncertainty principal isn't violated.

But you can't get it to do work, you can't extract more energy from vacuum fluctuations than you took out of it. If I have a cantilever MEMS switch, there is an attractive force between the lever and the base plate due to vacuum fluctuations from the change in the vacuum energy between when there was no matter and when we placed the switch into the vacuum. If we have a 0K temperature bath, then random motion of the molecules stop. If the Casimir force pulls on the switch in an oscillatory manner, causing it to vibrate, then we have to be extracting energy from the vacuum due to inherent damping and friction in the system. This we cannot do, at best there will be a constaint static force on the lever or it will be strong enough to close the switch but eventually it will reach some equilibrium state.

Plus, the uncertainty principle only comes into concerning measurements. We can have a system that actually has say zero kinetic energy without violating the uncertainty principle. The uncertainty principle only limits the degree of precision in how we measure the system between non-commutable observables.

http://www.calphysics.org/zpe.html

"In conventional quantum physics, the origin of zero-point energy is the Heisenberg uncertainty principle, which states that, for a moving particle such as an electron, the more precisely one measures the position, the less exact the best possible measurement of its momentum (mass times velocity), and vice versa. The least possible uncertainty of position times momentum is specified by Planck's constant, h. A parallel uncertainty exists between measurements involving time and energy (and other so-called conjugate variables in quantum mechanics). This minimum uncertainty is not due to any correctable flaws in measurement, but rather reflects an intrinsic quantum fuzziness in the very nature of energy and matter springing from the wave nature of the various quantum fields. This leads to the concept of zero-point energy."

"Zero-point energy is the energy that remains when all other energy is removed from a system. This behaviour is demonstrated by, for example, liquid helium. As the temperature is lowered to absolute zero, helium remains a liquid, rather than freezing to a solid, owing to the irremovable zero-point energy of its atomic motions"

I still think they may be erroneously applying the uncertainty principle. When calculating the vacuum energy, you do not consider uncertainty in any form, again, it only arises when one wishes to make statistical measurements of observables. When defining the wavefunctions and energy states, uncertainty is not brought into it in any way.

"Each mode is equivalent to a harmonic oscillator and is thus subject to the Heisenberg uncertainty principle. From this analogy, every mode of the field must have 1/2 hf as its average minimum energy."

They don't explain how the uncertainty principle comes into this. Are they implying that uncertainty is the cause for the non-zero energy in the ground state of an electromagnetic wave? Looking at the first paper listed, this is exactly what they are saying: "The Heisenberg Uncertainty Principle dictates that a quantized harmonic oscillator can never come entirely to rest, since that would be a state of exactly zero energy, which is forbidden." But there is nothing about the observables that forbids this, it is the eigenstates of the wavefunction itself that forbids it. The harmonic oscillator's ground state has a non-zero energy.

"The Casimir force is widely cited as evidence that underlying the universe there must be a sea of real zero-point energy. This argument follows from Casimir's analysis and prediction. It is not necessarily true, however. It is perfectly possible to explain the Casimir effect by taking into account the quantum-induced motions of atoms in each plate and examining the retarded potential interactions of atoms in one plate with those in the other."

Actually, Casimir's paper prior to his Casimir force paper did just this. He discovered that he error in the decay of the Van Der Waals/London force was due to the fact that the potentials did not take into account the finite speed of light, using retarded potentials corrected this. He then went on and calculated how this would effect bulk materials, like his plates (which was done using the disturbance to the vacuum energy instead). I believe the Casimir force for dielectric slabs is done via the molecular force and not the disturbance to vacuum. But again, these forces are not random forces though. Temperature is the average kinetic energy of a bulk, if we are going to hold a bulk at a temperature then we need to have the particles moving about in a random path in order to maintain confinement and a statistical net kinetic energy. How this arises out of static forces they do not say. All they stated was that:

"Zero-point energy is the energy that remains when all other energy is removed from a system. This behaviour is demonstrated by, for example, liquid helium. As the temperature is lowered to absolute zero, helium remains a liquid, rather than freezing to a solid, owing to the irremovable zero-point energy of its atomic motions. (Increasing the pressure to 25 atmospheres will cause helium to freeze.)"

No citations so I can't find out what they mean exactly. Just because it does not freeze does not mean that the zero point energy is giving up energy to the helium, increasing its temperature. It would be different if they said that as they cooled the liquid helium, the zero point energy was being absorbed into the helium, preventing it from cooling down further. I'll have to see what I can find in the Physical Review.

 

[Born2bwire]

Dammit, had a whole response written up and lost it.

Ok, I think we are talking about different things.

I am talking about the vacuum energy. The ground state of the electromagnetic wave has an infinite amount of energy in vacuum. When placing matter into the vacuum, this disturbs the ground state energy and the change in the energy results in the Casimir force. I do not believe, at least it hasn't been shown in the sources I have used, that you can extract energy out of this. The vacuum energy is sometimes called zero point energy.

You seem to be talking about the ground state of the matter itself, which is something different. It seems that using the appropriate intermolecular potentials (some of which I think can be attributed to the vacuum fluctuation disturbance), it can be shown that the ground state of a liquid is also non-zero. However, this seems to be a consequence of the properties and not due to extraction of energy from the vacuum (which is what I thought you were purporting). This property is also known as zero-point energy.

So in that respect I can agree that you will never reach absolute zero for a given system. Lord I hate these buzz-words.

 

[bsobel]

I do not believe, at least it hasn't been shown in the sources I have used, that you can

I never said you can extract energy from this, I simply said that all molecular motion does not stop at 0K, by definition all molecular motion can never stop.

So in that respect I can agree that you will never reach absolute zero for a given system. Lord I hate these buzz-words.

Its a terminology thing, but abs zero would simply be the state where ONLY the quantum flucuations are providing energy, no additional energy above that would enter the system.

 

[f95toli]

The fact that OK is not the same thing as "nothing moves" has -as far as I know- nothing to do with the Casimir force or even the vacuum.
You do not even need QED; it is just a result "ordinary" statistical physics.


I am reasonably sure you can find a discussion of this in Gardiner's book on Quantum Noise.

I've used the 1991 edition and this is presumably an updated version.
Note that this is a book dealing with graduate level physics, it is NOT a pop-sci book,

I've been planning to buy this book for a while (for work) , it is a good thing this thread reminded me about it

 

[firewolfsm]

Things cannot reach absolute zero as there will always be some quantum activity, akin to vacuum energy.

 

[f95toli]

Originally posted by: firewolfsm
Things cannot reach absolute zero as there will always be some quantum activity, akin to vacuum energy.

No, that is NOT the reason why we cannot reach absolute zero; read my replies above.
Again, even if we COULD reach 0K particles would still move (albeit very slowly).

Note that the "equivalence" between motion and temperature to some extent breaks down when you go to low temperatures; we run into all sorts of problem when we try to define what we mean by temperature well before these quantum effects become important (which is one of the reasons for why the internationall temperature scale currently only goes down to 0.65K)

 

[Locut0s]

Originally posted by: KIAman
does the item disappear from the universe? Assuming all motion stop including quantum.

This has been boggling my mind for the last several months. Is this why nothing can reach absolute zero because of conservation of energy?

The object can't disappear from the universe. Nothing truly can, see conservation of energy. By cooling a particle (read object) down all one is doing is reducing the particles kinetic energy (relative to the frame of reference of the person cooling the particle). Due to random quantum fluctuations though it's impossible to reduce a particles kinetic energy to absolute 0. And particles of mass have an inherent rest mass even at absolute 0. As silverpig mentions the one thing that would become more uncertain as one reduces the temperature would be the particles measurable location since one is pinning down the mass and velocity of the particle ever more precisely. This hardly means the particle ceases to exist though.

 

[William Gaatjes]

Originally posted by: bsobel

Interaction with the vacuum fluctuation will not affect it. You may get a momentary force that will move a part of the object but eventually a counteracting force will achieve equilibrium.

The point being is that the molecular motion doesnt not actualy stop if you could reach 0K, zpe actually prevents this. This negates the therotecial would the matter 'disappear' question if matter is indeed built of vibrating strings, enough vibrations continue due to ZPE to prevent the scenario the OP asked about.

I have a question, suppose that strings would vibrate at a much higher level then we know. And that everything we know and experience is based on subtract frequencies. When subtracting to waves, the resulting wave is a wave with a frequency of F1-F2. As a thought experiment and taking the speed of light as the not maximum , is that possible ?

Another thought experiment :
Lets say that photons move in a circulair motion, much like the shape of a spring. Now if it is possible to move in a straight line and oscillate faster that no interaction of meaning occurs, it would be possible to not be detected. But when these strings interact with eachother we get something we can actually measure.

What would your thougths be on that , just hypothetically thinking ?

 

[bsobel]

As a thought experiment and taking the speed of light as the not maximum

Yes if you consider the speed of light to not be the maximum then pink elephants can indeed fly.

 

[William Gaatjes]

Originally posted by: bsobel

As a thought experiment and taking the speed of light as the not maximum

Yes if you consider the speed of light to not be the maximum then pink elephants can indeed fly.

A pink painted elephant carried in an cargo plane does fly. It is a matter of perspective.
As is my thought experiment.

Then again, take the speed of light in vacuum as a maximum. WHat do you get then ?

 

[silverpig]

Originally posted by: William Gaatjes
I have a question, suppose that strings would vibrate at a much higher level then we know. And that everything we know and experience is based on subtract frequencies. When subtracting to waves, the resulting wave is a wave with a frequency of F1-F2.

This is wrong. That is not how waves add/subtract.

Originally posted by: William Gaatjes
Another thought experiment :
Lets say that photons move in a circulair motion, much like the shape of a spring.

You're just describing circularly polarized light.

Originally posted by: William Gaatjes Now if it is possible to move in a straight line and oscillate faster that no interaction of meaning occurs, it would be possible to not be detected. But when these strings interact with eachother we get something we can actually measure.

What would your thougths be on that , just hypothetically thinking ?

I have no idea what this is supposed to mean.

 

[William Gaatjes]

Originally posted by: silverpig

Originally posted by: William Gaatjes
I have a question, suppose that strings would vibrate at a much higher level then we know. And that everything we know and experience is based on subtract frequencies. When subtracting to waves, the resulting wave is a wave with a frequency of F1-F2.

This is wrong. That is not how waves add/subtract.

I guess you misunderstood me because if you where right we would not have any Rf device available today, that is if you mean by that. I will formulate : when for example 2 sinusodial signals are mixed together we get 2 new signals with accompanying frequencies : f1+f2 and f1 - f2. It is not simple adding and subtracting afcourse.

Originally posted by: William Gaatjes
Another thought experiment :
Lets say that photons move in a circulair motion, much like the shape of a spring.

You're just describing circularly polarized light.

And elektrons during a tunneling situation.

Originally posted by: William Gaatjes Now if it is possible to move in a straight line and oscillate faster that no interaction of meaning occurs, it would be possible to not be detected. But when these strings interact with eachother we get something we can actually measure.

What would your thougths be on that , just hypothetically thinking ?

I have no idea what this is supposed to mean.

[/quote]

Well, i will try to formulate it better when i can. My problem always have been that what i think i cannot catch in words that easy.

But i can say this : I am trying to bring al these experiments and effects together to see if there is something usefull.

To reply to you and others i will take a more conservative approach for now.

Ok, i am not saying that anything goes faster then light in a vacuum in reality. Although there are some theories that claim it is possible. I read something about tachyon condensation but that is new for me.

I was thinking about what i once read long ago about an experiment where a light pulse entering a material moved seemingly faster then light in vacuum does.

What was the trick:
The lightwave going trough the material was build up of lots of different seperate waves with different frequencies and amplitudes. Together they form a wave packet. The material properties cause the phases of the individual waves to shift and this causes the waveform packet so to speak to move ahead in time. In effect, you get a peak on the output while the input is still rising. It seems like an amplification and from a certain point of view it is, but it is not. It is playing around with phases, adding and subtracting sinusoidial signals with different amplitudes and frequencies. Again.

There is also an electronic experiment where the output seems to respond at input signals not yet applied. This afcourse is not true, It is just a mathematical trick. I found it very interesting. In effect, the output responds to the rising edge of the input signal with a characteristic way determined by all the waves with their own amplitudes and frequencies.
Therefore the pulse itself is not 1 frequency but build up of many sinusoidial signals. Fourier analysis in effect.


Hypothetically speaking :
Now if we apply this mathematical trick to the frequency domain of quantum mechanics,
i wonder what kind of possibilities arise.

EDIT : What would happen if this is also applied to the vibrating strings in the string theory ?

Especially since the amount of energy is sort of coupled with the wavelength. That is why i wonder if this trick can happen when we take multiple atoms and manipulate them in the right way. I was thinking what can be done with spectral lines.

Say we can excite the atoms in the lattice by use of pyroelectricity, by use of piezoelectricity : rayleigh waves. The skin effect may also be some way to more manipulate rayleigh waves which seems to move dependent on particle vibration. Moving the complete atom and the electrons around it seperately.

I wonder what can done with such a device. At least learn more from how particles behave and maybe find something interesting. We have a lot of harmonic oscillators in our universe. And they all interact. That is what is puzzling me about the models or i have misunderstood them.

 

[William Gaatjes]

I was thinking how it was done with the electronic circuit.
I have not yet found the article describing electronic circuit but if i remember correct , they use some differentiatior networks.

A Differentiator is a circuit that is designed such that the output of the circuit is proportional to the time derivative of the input.
(copied the explanation from wiki)

Modifying phases is also in the time domain. The material that causes light to advance is in effect differentiating the various single waveforms of that waveformpacket each in a unique way depending on that wavelenght. That is where the phase difference comes from and where the output wave packet seem to appear faster then would seemingly be possible.

I am willing to bet this is just one example of the complex interactions possible between "particles". I wonder if heisenbergs principle is based on this as well. Maybe because as soon as we do a measurement , we add a variable that causes another phase shift and the result is not what we would expect because we do not know yet how to correctly add in that offset.

 

[videogames101]

Originally posted by: William Gaatjes

Originally posted by: bsobel

As a thought experiment and taking the speed of light as the not maximum

Yes if you consider the speed of light to not be the maximum then pink elephants can indeed fly.

A pink painted elephant carried in an cargo plane does fly. It is a matter of perspective.
As is my thought experiment.

Then again, take the speed of light in vacuum as a maximum. WHat do you get then ?

But is the cargo plane on a treadmill?