Does Space Really Contain Nothing?

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Discussion Overview

The discussion revolves around the nature of space and whether it can be considered a true vacuum or if it contains negligible amounts of matter. Participants explore the definitions and implications of 'vacuum' and 'space,' addressing both theoretical and conceptual aspects.

Discussion Character

  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • Some participants suggest that 'vacuum' is a loosely defined term, often referring to areas with negligible matter, such as in orbit or between planets, where gas and dust are present but at very low densities.
  • Others argue that interstellar space is generally a hard vacuum, although it contains minute amounts of gas and dust, particularly in star-forming regions where density can block some light.
  • One participant compares the concept of a vacuum to asking how dark is dark, suggesting that interstellar space has a vacuum quality that surpasses what can be achieved on Earth.
  • There is a discussion about the observable universe and whether it can be considered a vacuum, with analogies made to boxes containing tennis balls or cargo containers with grains of sand to illustrate the ambiguity of 'emptiness.'
  • Another participant humorously connects the discussion to the philosophical paradox of the heap, suggesting that ignoring minute amounts of matter can lead to different interpretations of emptiness.

Areas of Agreement / Disagreement

Participants express differing views on the definitions and implications of a vacuum and the nature of space, indicating that multiple competing perspectives remain without a consensus.

Contextual Notes

The discussion highlights ambiguities in the definitions of 'vacuum' and 'space,' and the implications of considering minute amounts of matter in these contexts. There are unresolved nuances regarding the density of matter in various regions of space.

mklaben15
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Is space actually a vacuum or it is so large that any matter is negligible?
 
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'vacuum' is used fairly loosely. Essentially, its common use is merely 'where there is negligible matter'. We say 'it is a vacuum' in orbit, or on the Moon or between planets, but it isn't really. All these places are peppered with gas and dust, but the density is so small we tend to call it a vacuum for most intents and purposes (such as whether we can breather there, or if water will boil).

'space' is also an ambiguously-defined term. Space is not a thing that has a volume, unless you define the volume.

I think you're asking if the 'observable universe' is essentially a vacuum. Asking if the universe is a vacuum because it's so empty is like asking 'Can a box of tennis balls be considered empty if you ignore all the tennis balls in it?'
 
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Although there is gas and dust and other particles present in minute amounts, for the most part interstellar space is a very hard vacuum.
The density in star forming regions is marginally higher, but still is very tenuous, here the density is enough to block some light.
These are the dust lanes and nebulae that we see in images of galaxies.
Regions where it gets dense enough to collapse into a new star are rare, but it does of course happen.
 
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Its a little like asking how dark is dark. Generally speaking interstellar space has a harder vacuum than the best we can produce on earth.
 
Even an absolutely perfect vacuum isn't really empty as far as we know either.
 
DaveC426913 said:
I think you're asking if the 'observable universe' is essentially a vacuum. Asking if the universe is a vacuum because it's so empty is like asking 'Can a box of tennis balls be considered empty if you ignore all the tennis balls in it?'
Now, Dave, be fair. It's a lot more like asking 'can you consider a cargo container empty if there are a couple of grains of sand in it and you ignore them?'
 
phinds said:
It's a lot more like asking 'can you consider a cargo container empty if there are a couple of grains of sand in it and you ignore them?'
Damn, I think you just came up with a solution to the paradox of the heap ... well, kinda, anyway.

You just... ignore them.... lol...:oldcool:
 
The OP's question has been addressed. Thread closed.
 

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