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Can pressure be negative?

Michael Mozina said:
I already went through that whole Casimir debate with you folks.
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I know. It was hilarious. But my point was that you claimed that you claimed that RC's "understanding of pressure in a vacuum is flawed RC and rwguinn blew away your 'understanding' even before I posted a single thing to this thread" in spite of the fact that RC was discussing the Casimir pressure and rwguinn was not. Unless, of course, you can show us otherwise.

There is LESS pressure on the inside of the plates and MORE pressure on the outside. It's also a total red herring since you don't have a plate to work with in a VACUUM. More importantly the TYPE OF MATERIAL makes a difference, demonstrating *CONCLUSIVELY* that there is no area in the vacuum chamber with a "negative pressure" or the type of material would be irrelevant.
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Of course the type of material make a difference. If it didn't it wouldn't be the Casimir effect. The type of material makes a difference because in determines whether or note the vacuum excitations have nodes at the plates. If they do, then only vacuum fluctuations with wavelengths giving nodes at each plate are permissable.
 
Michael Mozina said:
That ideal gas law also clearly demonstrates the limits of pressure in a vacuum. It's zero, not negative infinity.
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That only makes sense if you take the ideal gas law as axiomatic. But it isn't. You can get it one of two ways: as an approximate fit to experimental data, or as a derived result of a model which uses approximations. In either case, the results are only approximate. Better models AND better experimental measurements prove that it is WRONG.
 
Please Michael, consider the following.

1) A container containing a fixed number of molecules of a (non-relativistic) gas

2) An elephant containing a fixed number of molecules in a (non-relativistic) solid.

3) A void in space containing only virtual excitations of the electromagnetic field.

What has most in common? 1 and 2, 1 and 3 or 2 and 3?
 
Tubbythin said:
I know. It was hilarious.
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I felt the same way actually. It was hilarious watching you folks ignore the influences of kinetic energy. It taught me a lot about the problem with astronomers today. They're pretty clueless when it comes to particle physics.

But my point was that you claimed that you claimed that RC's "understanding of pressure in a vacuum is flawed RC and rwguinn blew away your 'understanding' even before I posted a single thing to this thread" in spite of the fact that RC was discussing the Casimir pressure and rwguinn was not. Unless, of course, you can show us otherwise.
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I've already done so. No experiment of a vacuum on Earth takes place in anything other than a POSITIVE PRESSURE scenario. It's not even humanly possible to construct a 'zero pressure' vacuum. That alone should get you to drop your outrageous claim, but NOOOOOOO.

Of course the type of material make a difference.
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Then the PRESSURE OF THE *VACUUM* cannot be the cause or it wouldn't make a darn bit of difference.

If it didn't it wouldn't be the Casimir effect. The type of material makes a difference because in determines whether or note the vacuum excitations have nodes at the plates. If they do, then only vacuum fluctuations with wavelengths giving nodes at each plate are permissable.
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There are only two possible things that could cause those plates to come together. Either there is a RELATIVELY LOWER PRESSURE on the inside than the outside, or there is an attraction between the atoms at the atomic level. In neither case is it related to a "negative pressure" of the "vacuum' because no "vacuum" can even achieve a ZERO pressure.
 
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Ziggurat said:
That only makes sense if you take the ideal gas law as axiomatic. But it isn't. You can get it one of two ways: as an approximate fit to experimental data, or as a derived result of a model which uses approximations. In either case, the results are only approximate. Better models AND better experimental measurements prove that it is WRONG.
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You haven't come up with one yet that demonstrates that a vacuum holds "negative pressure".
 
Michael Mozina said:
I read Guth's paper edd. I saw him try to claim his "vacuum" had a "negative pressure". Inflation doesn't have any effect on "pressure" in any experiment on Earth. You're just "making it up" and then expecting me to agree with you - or else. The "or else' part is a ton of ridicule and claims about how "I just don't understand". It's like an astrologer telling me the I'm not ready to think about astrology yet because I don't agree with their claim before we begin.
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Your reply shows no understanding of my criticism - that you do not understand even non-inflationary big bang theories.
 
edd said:
Your reply shows no understanding of my criticism - that you do not understand even non-inflationary big bang theories.
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What exactly is your criticism then edd? Specifically what have I missed that demonstrates that a vacuum has a "negative" pressure?
 
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Michael Mozina said:
You haven't come up with one yet that demonstrates that a vacuum holds "negative pressure".
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Obviously one shouldn't expect a gas law to tell me what happens in a vacuum. That would be... oh, what's the word... stupid.
 
Michael Mozina said:
I felt the same way actually. It was hilarious watching you folks ignore the influences of kinetic energy. It taught me a lot about the problem with astronomers today. They're pretty clueless when it comes to particle physics.
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We aren't ignoring kinetic energy. Virtual photons do not have kinetic energy. There is no kinetic energy to ignore.

I've already done so. No experiment of a vacuum on Earth takes place in anything other than a POSITIVE PRESSURE scenario. It's not even humanly possible to construct a 'zero pressure' vacuum. That alone should get you to drop your outrageous claim, but NOOOOOOO.
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I'm not the one making the outrageous claim that the pressure exerted by virtual photons can be well described by the ideal gas equation.
By the way Michael, what value for n would you choose for the virtual photons in the vacuum?

Then the PRESSURE OF THE *VACUUM* cannot be the cause or it wouldn't make a darn bit of difference.
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The materials mark the boundary of the vacuum. They give the boundary conditions Without boundary conditions we'd have no solutions to pretty much anything in quantum mechanics.

There are only two possible things that could cause those plates to come together. Either there is a RELATIVELY LOWER PRESSURE on the inside than the outside, or there is an attraction between the atoms at the atomic level. In neither case is it related to a "negative pressure" of the "vacuum' because no "vacuum" can even achieve a ZERO pressure.
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Yes, you keep claiming in that but all you've got to show for it is the ideal gas equation. As I have demonstrated repeatedly the ideal gas law is completely inappropriate. As inappropriate as if it were used to describe the force exerted by an elephant on the Earth. Which bit of its complete inappropriateness do you not understand.
First of all, do you understand that real photons have completely different properties to gas molecules?
 
Michael Mozina said:
The fact you've been reduced to trying to use *TWO* things in a vacuum to demonstrate your claim about negative pressure is what is embarrassing. Your whole bang theory is predicted on having ONE and only one CLUMP of material, surrounded by nothing but a "vacuum". The fact you don't realize it's all about kinetic energy is also pretty damn embarrassing from my perspective.
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This Michael. You talk of a clump surrounded by vacuum. This is a common error, but a basic one.
 
Tubbythin said:
We aren't ignoring kinetic energy. Virtual photons do not have kinetic energy. There is no kinetic energy to ignore.
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Yes you are. You're ignoring the fact that every single atom in that Casimir chamber still has kinetic energy and it exerts PRESSURE and everything it hits. You're ignoring the kinetic energy of the neutrinos, the EM field and everything inside the 'vacuum'. In fact the fact you believe that photons do not have kinetic energy just demonstrates the problem! How do you figure the secondary of the coil in your car ends up with "current flow" if no kinetic energy transfers take place?

I'm not the one making the outrageous claim that the pressure exerted by virtual photons can be well described by the ideal gas equation.
By the way Michael, what value for n would you choose for the virtual photons in the vacuum?
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The photons also carry POSITIVE KINETIC ENERGY. There's more of it on the outside of the plates and less of it on the inside of the plates.

The materials mark the boundary of the vacuum. They give the boundary conditions Without boundary conditions we'd have no solutions to pretty much anything in quantum mechanics.
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Guth didn't have two plates to work with, so what are the "boundary" conditions of his "vacuum"?

Yes, you keep claiming in that but all you've got to show for it is the ideal gas equation. As I have demonstrated repeatedly the ideal gas law is completely inappropriate.
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No, it's not inappropriate to determine the lower limit of pressure in a vacuum because all vacuums contain SOME gas.

First of all, do you understand that real photons have completely different properties to gas molecules?
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Actually, in terms of their ability to transfer kinetic energy they aren't all that different. It's still just "kinetic energy".
 
edd said:
This Michael. You talk of a clump surrounded by vacuum. This is a common error, but a basic one.
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How does it affect this debate edd? Where is the vacuum in relationship to your "near singularity" thingy? What does that vacuum contain, and how does it interact with matter and/or energy?
 
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