Is it possible to create a region of negative density that is less than vacuum?

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Discussion Overview

The discussion revolves around the theoretical possibility of creating a region of negative density that is less than vacuum. Participants explore concepts related to negative mass, negative energy, and the implications of such phenomena in the context of the Casimir effect and cosmic expansion.

Discussion Character

  • Exploratory
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant suggests that the Casimir effect can create a region of negative density between two plates, questioning if such a region could be less dense than vacuum.
  • Another participant reflects on the idea of space being "strained" by massive galaxies, proposing that this could relate to dark energy and the concept of negative density exerting a repulsive force against gravity.
  • Some participants express uncertainty about the existence of negative mass or energy, noting that these ideas may have been largely discredited by the scientific community.
  • There is a request for clarification on the mathematical and theoretical faults associated with the idea of negative density or mass.
  • One participant corrects a misunderstanding regarding spatial expansion, emphasizing that matter does not pull space apart but rather is carried along with the expansion of space.

Areas of Agreement / Disagreement

Participants express a mix of curiosity and skepticism regarding the feasibility of negative density regions. While some share similar thought experiments, there is no consensus on the validity or implications of these concepts, and disagreements about the nature of space and gravity are evident.

Contextual Notes

Participants acknowledge limitations in their understanding of complex concepts such as the Casimir effect and the nature of dark energy, indicating a reliance on varying levels of knowledge and interpretation of scientific principles.

Omegatron
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So I know you can make a "negative density" region between two plates due to the Casimir effect. I know there's probably not, but is there any theoretically possible way to create a region of such negative density that the total density of the plates and region would be less than vacuum? I had a dream about little personal vehicles with fist-sized negative density regions that were so much less dense than anything that they floated buoyantly through the sky like little hover-scooters. Like a hot-air balloon, but smaller. :-)

If this is not possible, what kind of magic "negative energy" or "negative mass" or whatever would be needed to make it happen?
 
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I've had this same thought experiment too...

Thought about space being so empty and being pulled apart by massive galaxies enough to strain space to the point of "less than nothingness". Of course, I believe this has been thought of many times as a solution to "dark energy" problem where negative density/mass/energy/space would have a force repulsive to gravity thereby having these vast empty "less than nothing" spaces exerting a "pressure" onto super-huge macro objects like galaxies...a macro force to keep the galaxies from flying apart.

That's the concept, but this ultimatly boils down to "Does negative mass/energy exist? If so, will it have a repulsive effect when exposed to gravitational forces?"

I think these ideas have largely been disbanded by the scientific community for good reason I'm sure - but I really don't know - I think it was disproven or at least shown not to fit with the math. Someone more experienced and knowledgeable about this line of thought please exlpain the faults with this idea.
 
topside said:
I think these ideas have largely been disbanded by the scientific community for good reason I'm sure - but I really don't know - I think it was disproven or at least shown not to fit with the math. Someone more experienced and knowledgeable about this line of thought please exlpain the faults with this idea.

Yeah, I'm sure it's impossible, but I'd like to know why. You can learn a lot by considering impossible things.

I know the Casimir effect produces a region which has a lower "energy density" than vacuum, by "restricting the wavelengths of virtual particles" or some nonsense. :-) I wish I knew this stuff better.
 
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topside said:
I've had this same thought experiment too...

Thought about space being so empty and being pulled apart by massive galaxies enough to strain space to the point of "less than nothingness".
Hang on just a second here! Yet another misunderstanding of spatial expansion. Get thee to the astronomy/astrophysics forum. Space is expanding, and carrying matter with it. Matter is in no way 'pulling space apart'. The only effect that matter has is to try and bring more matter to it in accordance with the laws of gravity.
My apologies if that sounds harsh; I didn't mean it to be. It's a very common error, that seems to be the result of non-scientists teaching science. I'm certainly no expert, but at least I had very good books to teach me.
 
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