Absolute Zero and No Motion

[Alias Moniker]

The idea is that at absolute zero a particle would be without motion. But we try these experiments on a planet that's in motion in space time. Since we are in motion, a particle that is "not in motion" relative to us is not the same thing as a particle that is "not in motion" relative to space time.

So is absolute zero more than a temperature barrier? It is also about overcoming the motion of the particle through space time? Even if we could find out what zero motion is relative to the moving universe, would we still need to find out how to stop that particle's motion through time?

[Mordred]

you can't really tie down your definition of time to motion, as time is also a measure of duration, ie how long is it in that state, absolute zero is a temperature state.

 

now there is a problem with absolute zero and it has to do with the Heisenburg uncertainty principle. The lowest vacuum energy is defined as

 

[latex]e=\frac{1}{2}hv[/latex] this is called zero point energy in quantum mechanics, what this means is that absolute zero can never be fully reached.

 

this wiki page mentions that

http://en.wikipedia.org/wiki/Absolute_zero

http://en.wikipedia.org/wiki/Zero-point_energy

Edited July 24, 2014 by Mordred

[John Cuthber]

"The idea is that at absolute zero a particle would be without motion.".

No, not really.

It would have frozen out and become a solid but it would continue to vibrate so it never becomes stationary.

(Except in the case of superluid helium which has a zero point energy of motion, rather than vibration)

[Klaynos]

You also have to remember that there is no universal motion. Things move relative to other things. Also temperature is an ensemble effect.

[IM Egdall]

As a group of atoms approach absolute zero temperature, they form a Bose-Einstein condensate. Here they show primarily their wavelike behavior. All the atoms occupy the same space! Link has nice description:

 

http://www.colorado.edu/physics/2000/bec/what_is_it.html

Edited July 26, 2014 by IM Egdall

[Strange]

Note that only atoms with an even mass number (which, for complex reasons, is mainly atoms with both an even number of protons and an even number of neutrons) are bosons.

Edited July 26, 2014 by Strange

[studiot]

 

24 July 2014 - 01:35 AM

The idea is that at absolute zero a particle would be without motion.

 

 

The idea is that local vibration has ceased so there is no kinetic energy associated with this.

This says nothing about general solid body translational kinetic or potential energy.

This is why we cannot account the absolute internal energy of a body, only internal energy changes.

[xyzt]

The idea is that at absolute zero a particle would be without motion. But we try these experiments on a planet that's in motion in space time. Since we are in motion, a particle that is "not in motion" relative to us is not the same thing as a particle that is "not in motion" relative to space time.

The absence of motion is judged with respect to the crystalline network of the material, not with respect to some arbitrary frame. There is always going to be motion wrt. an infinity of arbitrary frames, this is not what absence of motion is referred to.

[John Cuthber]

 

 

The idea is that local vibration has ceased so there is no kinetic energy associated with this.

This says nothing about general solid body translational kinetic or potential energy.

This is why we cannot account the absolute internal energy of a body, only internal energy changes.

The local vibration does not cease at 0K.

There is still vibration there.

For it to stop vibrating would require its position (wrt the lattice) to be known exactly and that's a breach of the uncertainty principle.

 

And experimentally, we can look at the energy levels

http://en.wikipedia.org/wiki/Molecular_vibration#mediaviewer/File:Anharmonic_oscillator.gif

E_o is not zero.

[studiot]

Yes John, thank you for your correction.

 

Wave mechanics requires a zero point energy.

 

However this is unavailable to classical thermodynamics.

The (gas) velocities in the Maxwell-Boltzmann distribution do indeed tend to zero.

Further a freely rotating body has zero zero point energy.

[Enthalpy]

Maxwell-Botzmann supposes non quantification, hence does not deduce it. It's an asymptotic case with big volumes. Smaller volumes need QM which does introduce a minimum kinetic energy.

 

A freely rotating molecule does have a minimum rotation energy. It's this minimum energy, different for ortho- and para-hydrogen, that evaporates liquid hydrogen obtained as a mix of both forms.

[Maxila]

Since we are in motion, a particle that is "not in motion" relative to us is not the same thing as a particle that is "not in motion" relative to space time.

 

 

 

What you are missing is, there is no “entity”: that is space-time, even Einstein has said that in his book, “Relativity, the Special and the General Theory”, Page 155 under Appendix 5. Year 1952; "Space-time does not claim existence on its own, but only as a structural quality of the field."

 

While it is not a coordinate system it defines locations, “structural quality of the field”, with vectors and time. Motion only can exist relative to something else and space-time is not a something else, it describes the structure of something else.

 

you can't really tie down your definition of time to motion, as time is also a measure of duration, ie how long is it in that state, absolute zero is a temperature state.

 

 

 

I’m always uncomfortable when people say this because empirically there is no way to measure or experience duration without motion. A duration reference to something in a state, like temperature, will be to something else that has experienced motion (even if only the motion of their brain activity). In other words you can't define a duration without a reference to something else in motion.

[studiot]

Can't see why you can't experience duration without motion.

 

I am doing it right now by just sitting in my chair.

[John Cuthber]

In a way, it's true by definition.Since things don't stop moving, you can't experience anything without motion- because the motion is always there.

[timo]

Now there is a problem with absolute zero and it has to do with the Heisenburg uncertainty principle. The lowest vacuum energy is defined as

 

[latex]e=\frac{1}{2}hv[/latex] this is called zero point energy in quantum mechanics, what this means is that absolute zero can never be fully reached.

 

this wiki page mentions that

http://en.wikipedia.org/wiki/Absolute_zero

http://en.wikipedia.org/wiki/Zero-point_energy

Neither does the existence of a non-zero energy at T=0 imply that T=0 could not be reached, nor is that claimed in the Wikipedia pages you linked. What the two links claim is that thermodynamics assumes T=0 cannot be reached by thermodynamic processes (link 1) and that at T=0 the kinetic energy is not zero (link 2).

[Maxila]

Can't see why you can't experience duration without motion.

 

I am doing it right now by just sitting in my chair.

 

If you wrote this you must have brain activity (motion) without it you could not experience the duration. It's easy, and intuitive, to think of duration as motionless when the motion is hidden from direct view. It was the motions of your brain actitivy compared to the motionless body (sitting) that gave you the experience of duration. No different than measuring the state of temperature duration to the motion of a clock or your brain activity while watching it.

Edited August 7, 2014 by Maxila

[studiot]

Yeah, maybe, but if I was a rock face I would still endure.

 

Incidentally we are lead to the necessity of time in our analysis of our sensory input data about our surroundings.

[swansont]

 

I’m always uncomfortable when people say this because empirically there is no way to measure or experience duration without motion. A duration reference to something in a state, like temperature, will be to something else that has experienced motion (even if only the motion of their brain activity). In other words you can't define a duration without a reference to something else in motion.

 

Atoms are used to measure time and it does not rely on motion, just a state change (a spin flip for the most common clocks). And QM does not connect such a state change to any kind of trajectory. So not motion, as we know motion.

[Strange]

Yes, you end up defining motion as anything used to measure time (whether there is anything that is physically displaced or not) in order that you can insist that time is a result of motion. It is a purely circular argument.

 

Space is caused by rulers!

Edited August 7, 2014 by Strange

[Maxila]

 

Atoms are used to measure time and it does not rely on motion, just a state change (a spin flip for the most common clocks). And QM does not connect such a state change to any kind of trajectory. So not motion, as we know motion.

 

You posted this in the other forum and your understanding of the process is not accurate, read the paper by the NIST (The official time keepers of the US) I linked in the other forum. Yes a hyperfine transition is used but it is the the frequency of the photons emitted that are used to measure time (a photon changes position per wavelength) is an increment of motion.

[swansont]

 

You posted this in the other forum and your understanding of the process is not accurate, read the paper by the NIST (The official time keepers of the US) I linked in the other forum. Yes a hyperfine transition is used but it is the the frequency of the photons emitted that are used to measure time (a photon changes position per wavelength) is an increment of motion.

 

This will come as a great surprise to my boss. I work at the US Naval Observatory (The official timekeeper of the DoD, and the other official timekeeper of the US) and build atomic clocks. The frequency of emitted photons is not actually measured; the frequency is inferred from the number of atoms in each of the two hyperfine states. Which is irrelevant; the atom itself is the item being measured. It's the hyperfine transition that defines the second, or whatever clock interval is used (it need not be Cs), and that transition is not something you can point to as being motion.

 

You might want to consider the possibility that it's your understanding that's falling short here.

[xyzt]

 

You posted this in the other forum and your understanding of the process is not accurate, read the paper by the NIST (The official time keepers of the US) I linked in the other forum. Yes a hyperfine transition is used but it is the the frequency of the photons emitted that are used to measure time (a photon changes position per wavelength) is an increment of motion.

 

 

I do not know why the moderators don't let me post negs, you definitely deserve it for the above.

[Strange]

a photon changes position per wavelength

 

I am curious what this is supposed to mean. Could you explain it?

[timo]

I do not know why the moderators don't let me post negs, you definitely deserve it for the above.

I do not know either. But reading your post I get a few ideas. Generally, negative reputations tends to be given out sparsely on SFN in my experience (with maybe a bit increase lately, but that may be stochastic noise). It tends to be given for things like "this was really offensive", "troll post" and "quit ignoring anything that was said in the discussion and reposting the same claims all over again". In short, for bad behavior. Not as a shortcut for saying "you are wrong, but I cannot be bothered to correct you". I am not completely sure what "mods don't let me post negs" means exactly. But I do appreciate that the moderators here tend to support the discussion aspect of the forum and take measures to not let this forum turn into a point-and-click battleground.

[Maxila]

 

This will come as a great surprise to my boss. I work at the US Naval Observatory (The official timekeeper of the DoD, and the other official timekeeper of the US) and build atomic clocks. The frequency of emitted photons is not actually measured; the frequency is inferred from the number of atoms in each of the two hyperfine states. Which is irrelevant; the atom itself is the item being measured. It's the hyperfine transition that defines the second, or whatever clock interval is used (it need not be Cs), and that transition is not something you can point to as being motion.

 

http://etc.unitbv.ro...Measurement.pdf

(Section) 18.3

 

"As observed, the uncertainty of all clocks depends upon the irregularity of some type of periodic motion. By quantifying this motion, one can define the second"

 

 

I do not know why the moderators don't let me post negs, you definitely deserve it for the above.

 

If you have any actual scientific arguments to justify your innuendo, I'd be happy to discuss them.

Edited August 11, 2014 by Maxila