Pre Big Bang State

[Dubbelosix]

It seems like I was missing some terms in that last equation, but is all fixed.

[Dubbelosix]

I remember this very well, so I investigated this phenomenon years ago and I was assured, the system did not reach absolute zero. A terribly written headline. Sorry.

[exchemist]

https://www.nature.com/news/quantum-gas-goes-below-absolute-zero-1.12146  

Yeah but as I have commented before about these "negative temperatures", all this means is that they produce a population inversion.

 

If we take the  formula in my post 32: n(i) = n(0) p(i) exp (-εi/kT), then to get a greater population in the ith state than the ground state, you need the exponent to be +ve, which you can only do by assuming a -ve value for T.

 

But the whole thing is a bit silly, because temperature is only defined for a system at equilibrium, which a population inversion most certainly is not.   So in fact the formula does not apply  and so deducing that T is truly -ve is a flawed or meaningless conclusion.

[Dubbelosix]

However, you stated Plancks law and his correction zero point energy term was wrong. In fact, to be absolutely clear, you keep stating that zero point temperatures are attainable. You also stated his law can only apply to radiation and in a ground state, a thing does not radiate. But this is only true if you have a bad understanding of what contributes to a temperature. Motion, contributes to temperature, not radiation specifically. An oscillator, in a ground state can have a thermodynamic contribution to any square area of space. Negative temperatures, also, does not mean a system has reached absolute temperatures, or even below it in a true sense, since there is always the strange concept of ''negative motion.'' Nothing is ever frozen.

[OceanBreeze]

However, you stated Plancks law and his correction zero point energy term was wrong. In fact, to be absolutely clear, you keep stating that zero point temperatures are attainable. You also stated his law can only apply to radiation and in a ground state, a thing does not radiate. But this is only true if you have a bad understanding of what contributes to a temperature. Motion, contributes to temperature, not radiation specifically. An oscillator, in a ground state can have a thermodynamic contribution to any square area of space. Negative temperatures, also, does not mean a system has reached absolute temperatures, or even below it in a true sense, since there is always the strange concept of ''negative motion.'' Nothing is ever frozen.

 

What do you mean by "zero point temperatures"?

 

Absolute zero temperature and zero point energy are two distinctly different things.

 

Absolute zero temperature is the lowest possible temperature that is theoretically possible, whether  it is practically "attainable" or not! In classical physics all motion would be stopped at this point, but in quantum mechanics there would remain a residual zero point energy. This zero point energy means there is still some intrinsic motion remaining which allows the uncertainty principle to remain valid even at absolute zero temperature.

 

What part of this do you still not understand or disagree with?

Edited January 19, 2019 by OceanBreeze

[Dubbelosix]

Of course absolute temperature and zero point motion are two different things. In fact I have been saying this all along.

 

The crucial thing to remember, is that what we call zero point energy, is a ground state of energy, not the absence of it.

[exchemist]

It is, however, the absence of heat energy.

[Dubbelosix]

You clearly don't listen to a thing I have told you.

 

Motion translates to temperature, and oscillators have a motion - there is no absence of heat where there is motion and no absence of temperature where there is energy.

[OceanBreeze]

It is, however, the absence of heat energy.

 

That is the way I understand it also.

 

And the way I see it explained here:

 

QUOTE

 

Absolute zero is the lowest possible temperature where nothing could be colder and no heat energy remains in a substance.

Absolute zero is the point at which the fundamental particles of nature have minimal vibrational motion, retaining only quantum mechanical, zero-point energy-induced particle motion.

 

UNQUOTE

 

But, not worth arguing about.

[OceanBreeze]

Of course absolute temperature and zero point motion are two different things. In fact I have been saying this all along.

 

The crucial thing to remember, is that what we call zero point energy, is a ground state of energy, not the absence of it.

 

OK, I agree with this.

[Dubbelosix]

It is actually worth arguing about, because I find it quite incredible you and the other poster are absolutely unaware of classical mechanics. Do you even know how kinetic energy and temperature are related? You both clearly do not.

[Dubbelosix]

OK, I agree with this.

 

Then be assured, this was contested when I said this before.

[Dubbelosix]

https://www.reference.com/science/temperature-relate-kinetic-energy-c7c65dcf5fe026bb

 

 

.... and as your own article stated, the zero point field is a ground state of the motion. The oscillator must still have a kinetic energy.

[OceanBreeze]

https://www.reference.com/science/temperature-relate-kinetic-energy-c7c65dcf5fe026bb

 

 

.... and as your own article stated, the zero point field is a ground state of the motion. The oscillator must still have a kinetic energy.

 

 

OK, now I disagree with this.

 

I agree with your earlier statement because you make no mention of heat energy, only  zero point energy.

 

Heat is motion between atoms and between molecules. 

 

There is no heat inside an atom! The atom is the world of light, of radiation, not heat.

 

As the article I quoted says, at absolute zero (theoretically) there is only motion between the fundamental particles of nature.

 

Atoms are not fundamental particles. The fundamental particles inside atoms can move all they want, they will not generate any heat.

[Dubbelosix]

What is there to disagree with, what part of the following can you not comprehend:

 

1. Particles are always in motion and motion requires an energy which is what we call kinetic energy.

 

2. Due to the uncertainty principle, a particle can never be at a true rest. This means all oscillations of all fields contribute a motion.

 

3. The average kinetic energy translates roughly into the thermodynamic properties of a system.

 

 

 

Atoms, molecules... particles, call it what you want, all the above is still true.

[Dubbelosix]

be clear though, the physics gets complicated when thinking about fluctuations and kinetic energy, although the zero point energy term in Plancks formula arises totally analogous to a kinetic term. It becomes complicated because the motion of this field is made of off-shell particles which are not observable, which means this temperature is also not technically observable.

[OceanBreeze]

be clear though, the physics gets complicated when thinking about fluctuations and kinetic energy, although the zero point energy term in Plancks formula arises totally analogous to a kinetic term. It becomes complicated because the motion of this field is made of off-shell particles which are not observable, which means this temperature is also not technically observable.

 

OK, this is what I was getting at when I said there is no heat inside an atom because there are only fundamental particles, as you say not observable and also the temperature not technically observable.

 

I don't think we are in so much disagreement here and neither is exchemist.

 

To me, heat requires moving parts and friction between those parts.

 

There obviously is heat between molecules and between atoms but my understanding is there is no friction inside a single atom and there cannot be heat there, even if the fundamental particles are moving around due to zero point energy.

 

My understanding may be out of date so I am not so much arguing here as discussing.