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### Messages - Mr. Data

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1
##### Physics, Astronomy & Cosmology / How was Absolute Zero discovered?
« on: 03/08/2011 15:43:44 »
Now, I don't see a great difference here. If you set N = hv/(ehv/kT -1) = 0 then you still end up with the same result.

The derivation of the ZPE of a single quantum harmonic oscillator is here: http://en.wikipedia.org/wiki/Quantum_harmonic_oscillator

There is a huge difference because: 1) N is an integer for the harmonic oscillator, while N in your above equation isn't, and 2) these are completely different physical situations.  Yours is, from what I recall, an expression for the energy density of a black body radiator.  A quantum harmonic oscillator is completely different.

Thank you for the link. I will take back what I said about the equation. I admit it is based on a flaw, an incorrect application.

2
##### Physics, Astronomy & Cosmology / How was Absolute Zero discovered?
« on: 03/08/2011 15:42:54 »

Mr D - you really need to understand that absolute zero and zero-point energy are not the same thing.

I use zero temperatures, or absolute temperatures interchangeably.

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

The fact that zero-point energy is the energy remaining in a system at the limit T=0 does not logically imply, nor practically lead to the claim that zpe can only be observed at absolute zero.

Definition of the ZPE  -

''where ''zero-point'' refers to the energy of the system at temperature T=0, or the lowest quantized energy level of a quantum mechanical system.''

So it is stating that energy remains at T=0. You can use temperature interchangeably with energy or motion. As far as the definition is concerned, zero point energy is when temperatures are zero, and motion should no longer exist. It is entirely logical to assume that the zero point is not a factual temperature, since motion is never erradicated. So long as you have motion, your system cannot be said to be absolutely frozen, hence there is a temperature which cannot be quelled.

I don't recall any post claiming that the limit T=0 can be reached.  But whilst we cannot practically reach it - we state with certainty that at T=0 there is still a ground-state oscillation ie the zero point energy.

By what reasoning? If T=0 is never reached, how can speculations be given it is a true ground state? It seems outside the realm of testable physics.

It seems strange one can state with certainty that at T=0 there is still a ground state, if T=0 is never acheived.... think about it.

It is called zero-point energy because i) it would still be there at T=0 ii) you cannot go any lower.

Who says it would still be there, what evidence do you have that reaching T=0 reveals this prediction? Since we cannot reach the state T=0, then it seems redundant to make the speculation energy would still exist. Energy only exists because it cannot reach this state, not the other way around.

Note you never answered any of this. I will also remind you of my conjecture:

Let us not stray from the proposition being made. Zero point energy, the point at which motion should cease, does not. It is evidence enough to state that the definition of zero point energy is misunderstood.

It seems to be a strongly held belief that zero temperatures are reached, but there still remains a motion. This is an oxymoron.

Motion gives rise to temperature, so if there is no ceasing of motion, then how can your system really be called a zero point? In logical conclusion, zero point motion or temperatures (call it what you will) are never achieved.

3
##### Physics, Astronomy & Cosmology / How was Absolute Zero discovered?
« on: 03/08/2011 15:39:59 »
Quote
Zero point energy is the zero point temperatures at which motion should cease to exist.
Quote
Hence why a zero point energy (zero implying zero temperatures) is just nonesense.
Quote
You are implying zero point energy is real; this would mean you can freeze your system to absolute temperatures!!!!! This is impossible!
Quote
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.

The reason I have asked you to be more careful is the comments you have made so far in this thread - you will note they are in direct contradiction to what you are now seem to be agreeing with.

Elaborate. And note I will be away for the next hour or so, so make it good for my return.

4
##### Physics, Astronomy & Cosmology / How was Absolute Zero discovered?
« on: 03/08/2011 15:22:11 »
And I think it a bit sanctimonious of you to suddenly challenge my ability to read something. It's a common frequent thing here to see that kind of behaviour - we are all fallible, prone to mistakes. But I don't see you coming down on other people. Perhaps I left a mark with you?

5
##### Physics, Astronomy & Cosmology / How was Absolute Zero discovered?
« on: 03/08/2011 15:20:14 »
Mr D - please learn to read your own sources before contradicting others.  We know you picked it up wrong.  Why are you persisting to try and "answer" these questions when it is quite clear that you haven't even read up to a wikipedia level?

The speculations from the equations match those of JP's... after the equation given (which I presented) it simply states that

''According to this expression, an atomic system at absolute zero retains an energy of ½hν.''

Now, I don't see a great difference here. If you set N = hv/(ehv/kT -1) = 0 then you still end up with the same result.

6
##### Physics, Astronomy & Cosmology / How was Absolute Zero discovered?
« on: 03/08/2011 15:11:16 »
''the most famous such example of zero-point energy is E={\hbar\omega / 2} associated with the ground state of the quantum harmonic oscillator.''

From the same link. E={\hbar\omega / 2} is just the part of the remaining kinetic energy in the equation given.

7
##### Physics, Astronomy & Cosmology / How was Absolute Zero discovered?
« on: 03/08/2011 15:09:48 »
Or maybe I picked it up wrong...

8
##### Physics, Astronomy & Cosmology / How was Absolute Zero discovered?
« on: 03/08/2011 15:09:16 »
Not according to this:

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

''Then in 1913, using this formula as a basis, Albert Einstein and Otto Stern published a paper of great significance in which they suggested for the first time the existence of a residual energy that all oscillators have at absolute zero.''

9
##### Physics, Astronomy & Cosmology / How was Absolute Zero discovered?
« on: 03/08/2011 13:55:08 »
I don't know if I agree with you. Temperature is part of the equation which describes the ZPE for a single quantum oscillator:

ε = hv/(ehv/kT-1) + hv/2

If temperature cannot be defined for a single oscillator, how does it enter the equation?

10
##### Physics, Astronomy & Cosmology / How was Absolute Zero discovered?
« on: 03/08/2011 13:36:06 »
This is all detracting from the OP,but anyway...
It seems as though the link you gave is saying that the fluctuations can add energy to particles (cosmic rays),but not detract from them?Seems strange to me because if a particle moves through a zone that has a lower energy then it should suck energy away from the particle.Do the fluctuations not average zero?Seems like perpetual motion?

Take out some qoutations which highlight your incongruities, and we can analyze them.

11
##### Physics, Astronomy & Cosmology / How was Absolute Zero discovered?
« on: 03/08/2011 13:30:48 »
Well JP I've seen two definitions there. Either the 'Casimir force' belongs to matter itself, or to space. As for zero point energy, sure it exists, at least I expect it to do so. As for it needs absolute zero?

Yor_on, what is the meaning of defining absolute zero for a single particle?  Zero-point energy is meaningful and achievable for a single particle, temperature is not.

Well, zero point energy for a particle would be a particle which ceases to exist strictly by the classical definition. Of course, quantum mechanics has something else to say. Even if T=0, a particle will still move. Indeed, large collections of particles will move. Speaking of one particle, is just as rewarding if not simpler than speaking or concentrating on a system with a large amount of particles.

12
##### Physics, Astronomy & Cosmology / How was Absolute Zero discovered?
« on: 03/08/2011 13:03:53 »
It seems as though you are saying that temperature is really kinetic energy,and that there is no place where there is no kinetic energy?Ok i'll accept that, since as you say radiation has kinetic energy.
What do you mean by 10000th of a degree of error?
What do you mean by quantum fluctuations in space,is this a theory only or has it been measured?
I agree that space cannot be empty as all space has radiation in it.I just meant space without molecules.

By 10,000th of an error, this simply gives us a degree of freedom to allow certain parts of space to be slightly warmer than let us say the X-directionality. It is a smudge-factor.

Now, temperature can be thought of as a kinetic energy, or even the sum of the kinetic energy of the constituents of a macroscopic object. For instance, by theory it is said that a metal becomes hotter when the particles it is made of increase in kinetic energy. The faster they move, the hotter the object becomes.

As for quantum fluctuations, you may want to read this: http://arxiv.org/abs/gr-qc/0401082 - it is our best understanding of the vacuum in context of quantum mechanics.

13
##### Physics, Astronomy & Cosmology / How was Absolute Zero discovered?
« on: 03/08/2011 12:47:02 »
Careful my friend, there is no such thing as an empty space in physics. All of spacetime is occupied by quantum flucuations. Many of these flucuations only last a fraction of a second, but some are longer lived.

Anyway... temperature is valued in the cold of space where temperatures can vary to 10,000th degrees of an error. Since matter in the universe only occupies 1% of all spacetime, then it makes little justice to measure temperature in our daily acttivities. It makes more sense to measure temperatures in the deep of space where it is more or less homogenous.

14
##### Physics, Astronomy & Cosmology / How was Absolute Zero discovered?
« on: 03/08/2011 12:33:23 »
But yes... no mass.

15
##### Physics, Astronomy & Cosmology / How was Absolute Zero discovered?
« on: 03/08/2011 12:33:04 »
It might be more accurate to say that a photon is kinetic energy purely.

16
##### Physics, Astronomy & Cosmology / How was Absolute Zero discovered?
« on: 03/08/2011 12:22:55 »
Anyway, mass does not imply kinetic energy. A mass does have a kinetic energy, but kinetic energy is simply the energy of a moving particle. So a photon is simply a packet of kinetic energy.

17
##### Physics, Astronomy & Cosmology / How was Absolute Zero discovered?
« on: 03/08/2011 12:21:42 »
It has the homogenous appearance that the Background temperature is even to about 10,000th of an error. Quite a room for error.

18
##### Physics, Astronomy & Cosmology / How was Absolute Zero discovered?
« on: 03/08/2011 11:22:39 »
The article is also the closest thing I would agree with, it states:

''A system at absolute zero still possesses quantum mechanical zero-point energy, the energy of its ground state. The kinetic energy of the ground state cannot be removed. However, in the classical interpretation it is zero and the thermal energy of matter vanishes.''

As I said, the energy left over is not really anything special in the sense it is a ZPE - it is merely a kinetic energy of our system which refuses to vanish. T=0 will not imply a freezing of the system, hence T=0 is never acheived.

19
##### Physics, Astronomy & Cosmology / How was Absolute Zero discovered?
« on: 03/08/2011 11:20:50 »
Noting also:

''Absolute zero is the theoretical temperature'' - so absolute zero temperature is absolutely fine when speaking about the ZPE -

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

20
##### Physics, Astronomy & Cosmology / How was Absolute Zero discovered?
« on: 03/08/2011 11:18:56 »

Mr D - you really need to understand that absolute zero and zero-point energy are not the same thing.

I use zero temperatures, or absolute temperatures interchangeably.

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

The fact that zero-point energy is the energy remaining in a system at the limit T=0 does not logically imply, nor practically lead to the claim that zpe can only be observed at absolute zero.

Definition of the ZPE  -

''where ''zero-point'' refers to the energy of the system at temperature T=0, or the lowest quantized energy level of a quantum mechanical system.''

So it is stating that energy remains at T=0. You can use temperature interchangeably with energy or motion. As far as the definition is concerned, zero point energy is when temperatures are zero, and motion should no longer exist. It is entirely logical to assume that the zero point is not a factual temperature, since motion is never erradicated. So long as you have motion, your system cannot be said to be absolutely frozen, hence there is a temperature which cannot be quelled.

I don't recall any post claiming that the limit T=0 can be reached.  But whilst we cannot practically reach it - we state with certainty that at T=0 there is still a ground-state oscillation ie the zero point energy.

By what reasoning? If T=0 is never reached, how can speculations be given it is a true ground state? It seems outside the realm of testable physics.

It seems strange one can state with certainty that at T=0 there is still a ground state, if T=0 is never acheived.... think about it.

It is called zero-point energy because i) it would still be there at T=0 ii) you cannot go any lower.

Who says it would still be there, what evidence do you have that reaching T=0 reveals this prediction? Since we cannot reach the state T=0, then it seems redundant to make the speculation energy would still exist. Energy only exists because it cannot reach this state, not the other way around.

Liquid helium will not solidify (unless pressurized) even as limit of T=0 is reached
http://en.wikipedia.org/wiki/Liquid_helium
Casimir plates feel a force
http://en.wikipedia.org/wiki/Casimir_effect
The lamb shift of energies of orbitals in hydrogen atom
http://en.wikipedia.org/wiki/Lamb_shift

I don't see this as a proof. The articles will naturally not take into account the arguements I have given.

21
##### Physics, Astronomy & Cosmology / How was Absolute Zero discovered?
« on: 03/08/2011 10:34:29 »
Let us not stray from the proposition being made. Zero point energy, the point at which motion should cease, does not. It is evidence enough to state that the definition of zero point energy is misunderstood.

It seems to be a strongly held belief that zero temperatures are reached, but there still remains a motion. This is an oxymoron.

Motion gives rise to temperature, so if there is no ceasing of motion, then how can your system really be called a zero point? In logical conclusion, zero point motion or temperatures (call it what you will) are never achieved.

If anyone can prove this wrong, I welcome them.

22
##### Physics, Astronomy & Cosmology / Light speed?
« on: 03/08/2011 09:09:16 »
Well, Geezer is correct. The permeability and permittivity of spacetime determines the value of c... The energy density of the vacuum is also somewhat related. In theory, if you increased the overall energy density of spacetime, you can alter the speed of light, which means it changes the values of the permeability and permittivity. Notable mathematician John Barrow has done extensive work on this.

23
##### Physics, Astronomy & Cosmology / How was Absolute Zero discovered?
« on: 03/08/2011 06:26:45 »
Indeed I remain steadfast - now you ask me this in the appearance of a question.

why doesn't helium freeze unless you  apply about 25 bar pressure?

All the textbooks say it's down to ZPE. What's your explanation?

If zero point energy, is by definition:

where ''zero-point'' refers to the energy of the system at temperature T=0, or the lowest quantized energy level of a quantum mechanical system.

(From your link by calphysics) - then my explanation is more logical; that being systems have energy close to T=0 but can never be T=0 (and T=0 being where zero point truely exists), then in this case the energy we are really dealing with is the intrinsic energy of the particle. Note then energy remains as a stubborn refusal to reach zero point because this would directly violate the UP - so temperature arises in systems due to obiding by this principle, also meaning that zero point temperatures have never really been reached.

24
##### Physics, Astronomy & Cosmology / How was Absolute Zero discovered?
« on: 03/08/2011 04:55:08 »
Yor_on, each cell of space should have a ZPE associated with it.  This is what gives rise to the casimir force, in theory.  The ZPE allowed between two nearby conducting plates is less than outside, so there's a pressure.  As for gravity, ZPE is a quantum effect and there is no quantum theory of gravity, so who knows!

Mr. Data, you're confusing ZPE of a single state with T=0, which is only meaningful for many particles.  Certainly you can't reach T=0, which would mean putting all particles in a many-particle system in their ZPE states at the same time.   But some of those particles will be at ZPE without violating any physical laws.  It's kind of like rolling millions of dice.  You'll never get them all to come up 1's, but some of them certainly will in any given roll...

Well, fundamentally-speaking, this is all that counts. You can measure the mass of the universe in a single proton!

What do you mean, some of those particles will have ZPE without violating any laws? You do understand yourself that you surely that ZPE by definition is a system which is at T=0. These are by another name ''absolute temperatures''. Nothing can reach this. If it was T=0 then it must violate the Uncertainty Principle. NOT even a collection of particles, with a small sum of them will reach T=0. None of them by definition have actually reached zero temperatures.

25
##### Physics, Astronomy & Cosmology / How was Absolute Zero discovered?
« on: 03/08/2011 02:39:02 »
I'm not looking at it any specific way JP, more than saying that there is no ground state that I know of. But you state that there is, if I got you right? Maybe you are referring to defining a system as being in arbitrarily defined 'ground state'? Or maybe it is a theoretical definition of some other kind. What I did reading you was to go out on the net trying to find such a state in our universe? But it wasn't there :) But just as you can define space as a macroscopic ground state I presume that you can do so with a lot of other 'states' too.

That is, if you don't know that 'state' to exist, and can show me how to see it?

I think you've hit it on the button. No states can be made to reach T=0, so saying it should exist even when energy is not present seems decieving. I think I make a good arguement to say zero point temperatures don't actually exist. Also you are right about ground state, that can even apply to a macroscopic system, it could even apply to the universe as a whole! In fact, the entire universe according to current belief, is very much in a ground state.

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