Can pressure be negative?

[Michael Mozina]

Your failures are as basic as they could possibly be.

No, you're beliefs are as physically unsubstantiated as they could possibly be, starting with your 'higher than infinity' claims, your "negative pressure vacuum" claim, etc. As long as it looks good on paper to you somehow, you ignore the physics part entirely. You show me a finite experiment with a LOW temperature and then claim it's an example of 'greater than infinite temperature'. What a crock.

 

[Ziggurat]

No, you're beliefs are as physically unsubstantiated as they could possibly be, starting with your 'higher than infinity' claims, your "negative pressure vacuum" claim, etc. As long as it looks good on paper to you somehow, you ignore the physics part entirely. You show me a finite experiment with a LOW temperature and then claim it's an example of 'greater than infinite temperature'. What a crock.

How do you know it's a crock if you don't even know what temperature is?

And why are you so incurious that you refuse to learn what it is? It's almost like you're scared of learning more.

Let go of your fear, Michael.

 

[ben m]

How do you know it's a crock if you don't even know what temperature is?

You can't.

If you refuse to define temperature any more carefully than "a property of things I normally think of as hot" then you can violate the laws of thermodynamics.

That pesky "entropy" thing? Entropy never decreases, dQ = T dS and all that? There's no way to *derive* that from thinking about ideal gases and vibrations. (You might derive an empirical trend---"huh, I keep failing to build an engine that does better than X"---but you'll never know whether that arises from nature, or whether you're just doing it wrong.) Fat chance understanding that unless you actually know what T and S are.

Exotic systems where temperature has nothing to do with vibration? Sorry, that's not some physics pipe dream, that's standard technology. Adiabatic magnetic refrigeration, for example, is a phenomenon that's in practical day-to-day use in labs around the world. Understanding how it works requires you to assign a temperature---in Kelvin, the same units as usual---to an ensemble of spins. Not kinetic energy, not vibrations, not ideal gas molecules---just "some atoms are spin up, some are spin down", and that ensemble has a temperature. You bring the in and out of equilibrium with the ordinary vibration/kinetic temperature, and you can run this through a cycle that works as a refrigerator. Unsurprisingly, all of the formal mathematical machinery of statistical thermo (entropy, counting states, defining temperature as T = dS/dE, etc.) works like a charm.

Just think of all of those gadolinium spins (or whatever) that never once stopped to ask Michael Mozina how he intuitively wanted to assign their temperature, what he thought its range ought to be, etc. They just went about their business and obeyed T = dS/dE. Very rude of them. Right in the middle of an empirical lab experiment too!

(The surface of the Sun is much kinder. It's a solid shell of cold iron, inside a much hotter enclosure. It doesn't obey any laws of thermodynamics at all, does it? Good thing too, otherwise it might not work.) ETA: </sarcasm>

 

[Ziggurat]

If you refuse to define temperature any more carefully than "a property of things I normally think of as hot" then you can violate the laws of thermodynamics.

Not for the first time, either.

 

[Dilb]

Exotic systems where temperature has nothing to do with vibration? Sorry, that's not some physics pipe dream, that's standard technology. Adiabatic magnetic refrigeration, for example, is a phenomenon that's in practical day-to-day use in labs around the world.

Hey, I built one of those. It was my 4th year engineering project. Admittedly it was only supposed to cool stuff to ~1K, not the fancy nano-Kelvin stuff you get with nuclear demagnetization.

 

[Perpetual Student]

No, you're beliefs are as physically unsubstantiated as they could possibly be, starting with your 'higher than infinity' claims, your "negative pressure vacuum" claim, etc. As long as it looks good on paper to you somehow, you ignore the physics part entirely. You show me a finite experiment with a LOW temperature and then claim it's an example of 'greater than infinite temperature'. What a crock.

All of this has been explained again and again. This response is not science; it is a manifestation of willful ignorance combined with narcissistic crackpottery. Enough! Back on ignore!

 

[Dr. Trintignant]

Michael, I doubt there's much point in my trying to teach you something, but here goes anyway.
...
Now suppose you're doing your job surveying in a very mountainous area. You're surveying a grade that gets steeper and steeper until it becomes vertical, and then it actually curls over a bit more into an overhang.

Michael may never understand it, but for the rest of us who had no particular problem with infinite temperatures but were curious how they worked--thanks.

Is beta considered a "better" metric since its infinities correspond to physically unrealizable configurations?

- Dr. Trinitignant

 

[Ziggurat]

Is beta considered a "better" metric since its infinities correspond to physically unrealizable configurations?

Yes.

 

[sol invictus]

Michael may never understand it, but for the rest of us who had no particular problem with infinite temperatures but were curious how they worked--thanks.

Is beta considered a "better" metric since its infinities correspond to physically unrealizable configurations?

- Dr. Trinitignant

Well, it turns out that many characteristics of finite temperature systems (in fact, all characteristics of thermal equilibrium) can be computed in a formalism in which the inverse temperature beta corresponds to a periodic boundary condition. Specifically, beta is the period of imaginary time: one works in a "spacetime" where time has been analytically continued (i.e. it's like a 4th space dimension), and further, where only configurations that are periodic in imaginary time with period beta are allowed. That turns out to be completely equivalent to the standard thermal ensemble.

So beta is a length - it's the circumference of the thermal cylinder. In that language there's nothing particularly strange or unphysical about either beta going to infinity or zero, although zero is in some ways simpler.

 

[Michael Mozina]

How do you know it's a crock if you don't even know what temperature is?

And why are you so incurious that you refuse to learn what it is? It's almost like you're scared of learning more.

Let go of your fear, Michael.

Huh? It has nothing to do with letting go of 'fear', it's simply an appreciation of actual empirical physics as well as mathematical constructs. You can't point at a *finite* experiment that was conducted near absolute zero and tell me that it's *physically* an example of "infinite-plus" temperatures! You're confusing "mathematical shortcuts" with empirical physics *again*. This is what I mean by the idea that you folks cannot and do not comprehend the difference between *PHYSICS* and math.

 

[Ziggurat]

Huh? It has nothing to do with letting go of 'fear', it's simply an appreciation of actual empirical physics as well as mathematical constructs.

How can you appreciate physics when you don't even know the basic definition of what's being discussed? Definitions are a prerequisite for discussions of any kind. And you don't know them.

What is temperature, Michael? Why are you afraid to answer the question? If you don't know the answer, why are you afraid to ask, so that you might learn?

You can't point at a *finite* experiment that was conducted near absolute zero and tell me that it's *physically* an example of "infinite-plus" temperatures!

Obviously I can, because I did.

 

[Dr. Trintignant]

Specifically, beta is the period of imaginary time: one works in a "spacetime" where time has been analytically continued (i.e. it's like a 4th space dimension), and further, where only configurations that are periodic in imaginary time with period beta are allowed. That turns out to be completely equivalent to the standard thermal ensemble.

I did a bit of reading and it appears that the formalism you're talking about is (at least in part) the Wick rotation. While I don't grok it yet, from the Wiki article I can see how (at least in limited scenarios) it connects Feynman's path integrals to statistical mechanics. An e^t in your 4th space dimension turns into a periodic function when you substitute the i back in.

I will say that my first impression of these kinds of things is that they're mathematical "tricks" without any real grounding in reality. But when the tricks allow you to made predictions that you otherwise would not have, you have to wonder if the transformed universe is not actually closer to reality than the apparent one. The universe doesn't have to abide by our intuitions. Imaginary time seems crazy... but no more so than how the universe actually behaves.

- Dr. Trintignant

 

[Michael Mozina]

How can you appreciate physics when you don't even know the basic definition of what's being discussed? Definitions are a prerequisite for discussions of any kind. And you don't know them.

You are talking about mathematical "trickery", not physical definitions related to real physical particles. What you're talking about is a mathematical "handy dandy trick" that "seems" (to you at least) to represent something "higher than infinite temperatures". What you failed to do is make any empirical physical connection to anything in the real world. What you "trotted out" is an experiment conducted with "finite" numbers of atoms, at *extremely low* temperatures, where the internal energy state of the atoms could achieve a "slightly lower" overall energy state.

You're then insisting this somehow represents a temperature that is "higher than infinity" (whatever that might be), and you ignored the atomic physics entirely. You don't do conceptual physics, just "imaginary math" and you "imagine" that your math is a "physical reality" rather than a "handy tool" in extreme conditions.

This is *exactly* what I mean about you folks and the fact you do not do physics. All you understand are mathematical constructs, and you're clueless at the level of actual physics.

What is temperature, Michael? Why are you afraid to answer the question? If you don't know the answer, why are you afraid to ask, so that you might learn?

What did you expect to "teach me" from a "finite" experiment done with "finite" numbers of atoms, that never reached 2 degrees Kelvin during the time in question?

Obviously I can, because I did.

No Zig, you did not. In fact you shot your entire argument in the foot based on the "physical experiment" you chose to try to defend the bizarre notion of "infinity+" temperatures in atoms that never achieved 2 degrees Kelvin during the time in question. Hoy.

 

[sol invictus]

I will say that my first impression of these kinds of things is that they're mathematical "tricks" without any real grounding in reality. But when the tricks allow you to made predictions that you otherwise would not have, you have to wonder if the transformed universe is not actually closer to reality than the apparent one. The universe doesn't have to abide by our intuitions. Imaginary time seems crazy... but no more so than how the universe actually behaves.

I would say it like this. We have some mathematical models we think describe the world. These models make predictions. So we perform experiments to test a model, and if it holds up, we keep it. Models that are pretty well established - like those of thermodynamics - help us choose the simplest set of parameters to use to describe systems (like temperature, entropy, etc.). Ultimately, these parameters are defined in terms of the model, not by the experiment, and they can only be discussed in terms of the model.

Nothing in that process requires the model or its parameters to conform to any kind of intuition or prior expectation - if it makes predictions that are consistent with experiment, it's a (potentially) valid theory. Since our intuition is mainly based on a certain limited subset of those experiments, it doesn't add anything.

Regarding this ridiculous "argument" with Mozina: Mozina has some concept of temperature (that he refuses to articulate) that apparently doesn't allow it to be infinite. Physicists have another definition of temperature - a definition based on mathematical models developed over centuries of study and experiment - that does allow infinities (and negative values) under certain circumstances. That's all there is to it.

 

[sol invictus]

This is *exactly* what I mean about you folks and the fact you do not do physics. All you understand are mathematical constructs, and you're clueless at the level of actual physics.

By the way, Mozina - this infinite and negative temperature stuff can be found in every textbook on thermodynamics. Most physics students learn about it, essentially all professional physicists understand it. So to say it isn't "actual physics" is patently absurd.

The first reaction of many students when they first encounter it is similar to yours - they are puzzled and surprised that such a thing is possible. But they quickly learn how and why it is in fact possible, and why the standard definition of temperature that makes that the case is the most useful one, and the one that does in fact conform to our intuition in situations where it ought to apply.

 

[Skwinty]

Is it not true that infinities and singularities tend to indicate a breakdown in the physics?

 

[Michael Mozina]

By the way, Mozina - this infinite and negative temperature stuff can be found in every textbook on thermodynamics. Most physics students learn about it, essentially all professional physicists understand it. So to say it isn't "actual physics" is patently absurd.

The first reaction of many students when they first encounter it is similar to yours - they are puzzled and surprised that such a thing is possible. But they quickly learn how and why it is in fact possible, and why the standard definition of temperature that makes that the case is the most useful one, and the one that does in fact conform to our intuition in situations where it ought to apply.

FYI, this conversation started when Zig said that it achieved an "above infinite" temperature.

His own experiment demonstrates that is not the case. Not only was the temperature of the experiment "finite", it never even achieved 2 degrees Kelvin during the entire time in question. What it did achieve is an internal entropy change inside of the atom that will eventually 'return to normal' the moment we take away the field/extra energy. Not only did this experiment *not* achieve an "infinite" temperature inside the atom, it could not possibly do so because the energy input itself was "finite" to start with! The only thing that changed during the time in question is an internal spin arrangement inside the atom, not the actual "temperature" of the atom, or anything inside of the atom.

Mathematics is a useful tool, but in the wrong hands it leads to all sorts of strange ideas that people "believe in" and simply "take for granted", that are simply not supported by experimentation.

Zig is essentially claiming to create a "greater than infinite" temperature with finite energy source.

http://www.internationalskeptics.com/forums/showpost.php?p=7106966&postcount=333

 

[Ziggurat]

You are talking about mathematical "trickery", not physical definitions related to real physical particles.

The definition of temperature is not "trickery". But then, you don't even know what the definition is.

This is *exactly* what I mean about you folks and the fact you do not do physics.

Is that kind of like how you don't do math? Or is it like how you don't do definitions?

What is temperature, Michael? Why is this a question you're avoiding? Shouldn't it be rather simple to answer?

What did you expect to "teach me" from a "finite" experiment done with "finite" numbers of atoms, that never reached 2 degrees Kelvin during the time in question?

I no longer expect to teach you anything, because you have, for years now, refused to learn. Starting with the fact that you refuse to learn the very definitions of the words you use.

 

[Ziggurat]

Is it not true that infinities and singularities tend to indicate a breakdown in the physics?

Well, they can indicate that, but they certainly don't have to.

For example, if you do simple Newtonian mechanics in polar coordinates, you quickly run into singularities and infinities at the polar axis. These don't indicate any problems with Newtonian mechanics, they're just the result of our choice of coordinates. If you want, you could view infinite temperature as being similar (the result of choosing temperature rather than Beta). But it's not a breakdown of physics, physics can handle infinite temperatures quite well without any problems.

 

[sol invictus]

FYI, this conversation started when Zig said that it achieved an "above infinite" temperature.

That's the best way to describe it - it's no different than saying that an overhang is steeper than a vertical cliff. While it might sound odd that something can be steeper than vertical, rock climbers will nevertheless agree.

His own experiment demonstrates that is not the case. Not only was the temperature of the experiment "finite", it never even achieved 2 degrees Kelvin during the entire time in question. What it did achieve is an internal entropy change inside of the atom that will eventually 'return to normal' the moment we take away the field/extra energy. Not only did this experiment *not* achieve an "infinite" temperature inside the atom, it could not possibly do so because the energy input itself was "finite" to start with! The only thing that changed during the time in question is an internal spin arrangement inside the atom, not the actual "temperature" of the atom, or anything inside of the atom.

Mathematics is a useful tool, but in the wrong hands it leads to all sorts of strange ideas that people "believe in" and simply "take for granted", that are simply not supported by experimentation.

Then you need to start a letter-writing campaign to the publishers of every book on thermodynamics.