[Mr. Data]

I was perfectly right in what I said though. Zero Point energy is not a theoretical idea. It's a scientific principle. You cannot reach zero momentum; that would directly violate the UP.

[Bored chemist]

You were "perfectly right" in that you said "It was proposed in 1913", but it was documented nearly half a century earlier and follows from work done in the 1780s.
http://en.wikipedia.org/wiki/Charles's_law

and also from even earlier work going back at least to the work in 1702 by Amontons.

I agree that you can't reach absolute zero.
Nernst pointed that out.
http://en.wikipedia.org/wiki/Third_law_of_thermodynamics
Interestingly, he did so just before 1913.

Zero point energies do exist and, for some systems they are a requirement of the UP.
However, while that's true for a vibrating molecule, it's not true for a lot of particles.
If they are stationary then the uncertainty of the momentum is zero, but, provided that you don't know where they are (ie the uncertainty of the position is infinite), that's not a violation. It applies to the much loved "particle in a box" but not to a free particle.

(if the vibrating molecule stopped vibrating the position of one atom WRT the others would be fixed, and so would its momentum. That's forbidden.)

[Mr. Data]

Stop, stop stop!

Who said zero-point energies where a fundamental principle? Anything which imposes zero momentum implies an exact spacial coordinate... This is ALWAYS forbidden... who you reading from, englighten me please.

[Mr. Data]

The concept and workable mechanism behind the experimental evidence behind the zero-point field should be no more complicated than excepting that spacetime, and every planck unit which occupies it, is constantly fuelled with a smallest unit of energy. This energy will at it's lowest energy refer to the kinetic energy of a vibrating energy 1/2 hbar \omega. You cannot have a unit of spacetime reach T=0 as much as you cannot accelerate it to c. Notice that the lowest speed possible will not equal v=0, as much as it's maximum speed will never reach c... everything is always in motion.

[Bored chemist]

"who you reading from, englighten me please."
My old University notes; probably Atkins or Richards. Anyway, whoever it was I think they had the advantage over you of not saying both
"Zero Point energy is not a theoretical idea. "
implying that it's real and
"This also means the zero point energy does not actually exist! "
saying that it's not.
Perhaps, when you have made up your mind,...

[Mr. Data]

Ask yourself this. How can the zero point even exist, if no one can ever reach that state? Zero point energy is a real unnattainable limit. It is not an idea, it is a measure of experimental fact.

[Bored chemist]

Ask yourself this. How can the zero point even exist, if no one can ever reach that state? Zero point energy is a real unnattainable limit. It is not an idea, it is a measure of experimental fact.

You still don't seem sure if it's experimentally real or purely hypothetical.
Incidentally, a good fraction of the nitrogen molecules I am breathing are in the bottom excited vibrational state. Their properties are dependent on the existence of zpe.
You don't have to get to absolute zero to achieve that.

[Mr. Data]

No, I'm quite sure of what I have said. You simply are not understanding what I telling you. Again, how can a real T=0 (as a temperature exsit) when T=0 cannot be reached? No matter how much cooling energy you pump into your apparatus, there is no way you can ever reach ZPE. There is always energy, always heat attributed to any vibrating energy.

[Bored chemist]

Try reading this.
As I said before, many or most of the nitrogen molecules I am breathing are in the vibrational ground state.
The only vibrational energy they have is zero point energy.
That's the real world, yet you seem to wan to insist it's not possible.
You seem not to have noticed that, at normal temperatures, most energy is translational.
That's why it's wrong to say "There is always energy, always heat attributed to any vibrating energy."
If it's zpe there's no heat associated with it.

[Mr. Data]

Lol... are you trying to joke this?

You do realize that the terminology zero point energy is misleading? Ground state energy is something far different than a system achieving zero point energy. It is not called a [zero point] for nothing you know. Zero, the non-existing of temperatures... energy, just as it says on the tin. Except T=0 is never accomplished, and what you have left over is a system with 1/2 hbar omega. You are not gaining energy from a zero point field, it is the energy you have left over when you reach this value of 1/2 hbar omega. It is not caused by a system reaching zero point energy (or by definition T=0) but is caused by the lack of it's ability or work to reach T=0.

Why can't you understand this? Indeed, why does anyone treat the zero point field as something a particle can reach? You don't freeze an electron down to zero temperature, then expect energy to be left over. You try and make the system reach zero point energy, but as I have shown countless and countless time before, this is impossible.

[Mr. Data]

If it's zpe there's no heat associated with it.


Which is exactly my point bored chemist. If there is no heat, there is no ZPE. But in all cases, there is an energy and momentum associated to every particle in the universe, so by logical deduction, ZPE is non-existant. You just proved my own case.

[Bored chemist]

From WIKI
" the energy of the ground state is known as the zero-point energy of the system."

From Mr Data
"Ground state energy is something far different than a system achieving zero point energy."


From Mr Data
"You try and make the system reach zero point energy, but as I have shown countless and countless time before, this is impossible."
In reality, most of the molecules in the air around you are in their vibrational ground states and have the ZPE which you need to account for if you want to explain their spectra.

"You don't freeze an electron down to zero temperature, then expect energy to be left over. "
Ignoring the fact that the first half is impossible, actually I do. Once you get cold (and room temperature will be quite cold enough for a lot of cases) there's not enough energy (on average) to get something out of the ground state. So it sits in the ground state, but as we both agree, it has to be moving in order to comply with the UP. The energy associated with that movement is the ZPE.

I'm sure anyone reading this will come rapidly to their own conclusion

For those who care,
The vibrational frequency of nitrogen is 2331 cm^-1
Equivalent to about 0.29eV
At room temp the mean energy is about 0.026 eV
Boltzmann's law gives n/n(o)= e^-(0.29/0.026)
So about  14 molecules in each million are in the first excited vibrational state.
The rest are in the ground state.
99.985 % are in the state Mr Data says you can't reach.
"You try and make the system reach zero point energy, but as I have shown countless and countless time before, this is impossible."

[Mr. Data]

You are implying zero point energy is real; this would mean you can freeze your system to absolute temperatures!!!!! This is impossible!

The ground state is simply the lowest energy state for any system, like a longitudinal photon is to mexican hat potential.

In reality, most of the molecules in the air around you are in their vibrational ground states and have the ZPE which you need to account for if you want to explain their spectra.

In what sense? Are you saying molecular objects which perhaps absorb zero point flucuations? This I would agree with. Fluctuations of the zero point energy field however, are not borne from systems which reach zero temperatures.

Ignoring the fact that the first half is impossible, actually I do.

Now you are confusing me!

Yes, the first half is impossible, and this is because no system, no molecular, no atomic, no subatomic system can be frozen to zero temperatures, so explain to me how your sentance makes more sense, than saying a particle does not reach zero temperatures because of the energy left over?

Yes... anyone reading this should come to their own conclusions. It makes absolutely no sense to speak of a zero point energy as an ''existing'' temperature. It is a limit, an unnatainable limit, because:

A) It will require an infinite amount of energy for a system to reach T=0

B) Every particle in the universe always has a momentum (and this is attributed directly to ZPE) - except it is an energy which will stop a system reaching T=0 - the system never actually reaches this mythical limit!!


So perhaps any confusions will be settled on this part:

Once you get cold (and room temperature will be quite cold enough for a lot of cases) there's not enough energy (on average) to get something out of the ground state. So it sits in the ground state, but as we both agree, it has to be moving in order to comply with the UP. The energy associated with that movement is the ZPE.

Right, except the energy associated to the ZPE is nothing but an intrinsic momentum inherent in aboslutely every system! It is just another fancy word, for yet another deceiving model of physics. ZPE does not exist, and can never be reached. Any energy in a system is not a contribution of ZPE in many cases - it is simply a part of the momentum of the system. If you could, however, freeze an object to asbolute zero temperatures first, then somehow revive that particle to some mometum through a contribution of some field, then yes... this would be an energy associated from the movement of a zero point field, keeping in mind a zero point field is exactly how I defined it earlier: It is the zero temperature associated to freezing a quantum system.

But dare I say anymore... such systems being frozen is impossible, because as you said, we seem to agree this would violate the Uncertainty Principle.

[Bored chemist]

You keep talking about fields.
Are you referring to this sort of thing?
"Vacuum energy is the zero-point energy of all the fields in space"
(from http://en.wikipedia.org/wiki/Zero-point_energy  )

If you are talking about the zero point energy of a vacuum then it's clearly not the same as talking about the zero point energy of something concrete- like the nitrogen molecules which are (practically) all in the vibrational ground state.
A vacuum doesn't have a temperature so it's clearly got little or nothing to do with the topic.
Why did you bring it up?
Never mind.
No matter how cold you get a nitrogen molecule, it will vibrate at just the same frequency, and with just the same energy as the ones you are breathing.
That energy- the energy associated with the ground state isn't zero. The atoms have potential and/ or kinetic energy.
They are (as we agree) moving.
The vibrational ground state of a nitrogen molecule has has got energy. It has about 0.15 eV of energy
It will continue to do so no matter what you say in reply to this.
It will also remain the case that you said "Ground state energy is something far different than a system achieving zero point energy." in direct contradiction of the received wisdom.
You also said "No matter how much cooling energy you pump into your apparatus, there is no way you can ever reach ZPE. "
which is nonsense- you just breathed in billions of billions of counter-examples.

[Mr. Data]

A vacuum doesn't have a temperature so it's clearly got little or nothing to do with the topic.

A vacuum does have a temperature - temperature is measured by the energy which fills the space you measure. There is no such thing as an ''empty space'' in physics, every small part of spacetime is filled with energy. In fact, relativity determines that the vacuum is a physical sheet and that the seperation of energy from any part of spacetime is impossible. So yes, a vacuum does contain a temperature.

I have heard people state that the vacuum does not technically have a temperature because it implies energy, but anyone with a deep understanding of relativity will know that the vacuum is a physical dynamical sheet of bubbling quantum particles - spacetime is the appearance of matter-energy. The two cannot be seperated.

Indeed, the vacuum temperature is best known as the Microwave background temperature also, the left over remnant of the big bang http://arxiv.org/abs/astro-ph/0012222

No matter how cold you get a nitrogen molecule, it will vibrate at just the same frequency

Actually, you cannot make a molecule reach zero temperatures. This would mean the absence of movement, I thought we covered this.

That energy- the energy associated with the ground state isn't zero. The atoms have potential and/ or kinetic energy.
They are (as we agree) moving

Right. The system never reaches zero temperature as this would imply zero momentum. Hence why a zero point energy (zero implying zero temperatures) is just nonesense.

The vibrational ground state of a nitrogen molecule has has got energy. It has about 0.15 eV of energy

I won't deny this. In fact, whatever energy is there, is part of the dynamical system itself. It is the instinsic energy of the system, not something borne from absolute zero temperatures.

You also said "No matter how much cooling energy you pump into your apparatus, there is no way you can ever reach ZPE. "
which is nonsense- you just breathed in billions of billions of counter-examples.

This part is troubling you the most. What is it which makes my statement unclear when I explain this? Zero point energy is the zero point temperatures at which motion should cease to exist. But since energy cannot be frozen to absolute values, then the particle can never reach zero point energy. Zero point energy is just a refusal to be frozen! It doesn't reach T=0, it keeps on trucking because of the UP.

[Bored chemist]

Sorry for my poor use of language there.
I should have said that a vacuum doesn't have a temperature that we can set to absolute zero, so it has little or nothing to do with the topic.

"Actually, you cannot make a molecule reach zero temperatures. This would mean the absence of movement, I thought we covered this."
Strawman; since I never said you could.
I said "No matter how cold you get a nitrogen molecule, it will vibrate at just the same frequency" which is true.

"Right. The system never reaches zero temperature as this would imply zero momentum. Hence why a zero point energy (zero implying zero temperatures) is just nonesense. "
You keep missing the point.
Even if we could get it to zero it would continue to vibrate with ZPE.

Re, The vibrational ground state of a nitrogen molecule has has got energy. It has about 0.15 eV of energy
you said
"I won't deny this."
I think you  already did.
"No matter how much cooling energy you pump into your apparatus, there is no way you can ever reach ZPE"


And, as another example,
"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.)" from
http://www.calphysics.org/zpe.html

[Mr. Data]

Strawman; since I never said you could.
I said "No matter how cold you get a nitrogen molecule, it will vibrate at just the same frequency" which is true.

When you said no matter how cold we make a nitrogen molecule, I thought you were implying our limit of T=0. Of course, this is impossible.

Even if we could get it to zero it would continue to vibrate with ZPE.


But we can't which is my point in its entirity. So how do we destinguish vibrational energy from zero point energy? To know the latter, surely a system first needs to reach T=0?

"Zero-point energy is the energy that remains when all other energy is removed from a system.

What?

If you remove the energy system in question, then what are you cooling down to T=0? By remove, what is meant here? You remove a peice of energy (or simply move it from one place to another) vacuum fluctuations take its place; that isn't zero point energy as we are taught by the reasoning of a zero temperature... Though that seems to be a popular answer. By effect, that is simply just another kinetic system which has taken the place of our previous system. No need for superfluous names like zero point energy, or temperatures.

[Mr. Data]

You're link says this:

Quantum mechanics predicts the existence of what are usually called ''zero-point'' energies for the strong, the weak and the electromagnetic interactions, where ''zero-point'' refers to the energy of the system at temperature T=0

I thought me and you covered this has to be fundamentally incorrect?

[yor_on]

Due to quantum fluctuations there can be no 'zero point' for anything. And that one is also Heisenberg's uncertainty principle as far as I know. 'Space' from a QM point of view is in a constant 'shivering', never at rest as the Casimir effect show us.

What we call 'zero' is a place where I expect everything to be at rest, and?
That doesn't seem to exist. Which is weird.

[yor_on]

As it actually, if lifted up to a principle, states.

There is no universal 'ground state'.
==

Although, locally we have one, 'c'.
And if 'chopped up', we come to the Plank scale in where we can't chop it up any more, as far as I understand as that is where the distance travelled by light in one Planck time becomes one Planck length. And we can't make it any better than that.