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  #1  
Old December 10th 16, 11:26 PM posted to sci.space.history
[email protected]
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Default Outer space

If nature abhors a vacuum, why then is space pretty much a vacuum?Just got
thinking about it last night.
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  #2  
Old December 11th 16, 04:04 PM posted to sci.space.history
Jeff Findley[_6_]
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Default Outer space

In article , rfdjr1
@optonline.net says...

If nature abhors a vacuum, why then is space pretty much a vacuum?
Just got thinking about it last night.


Perhaps we should modify that to: Nature abhors a vacuum when you live
at the bottom of a large gravity well.

When you are far away from a large gravity well, there simply isn't
enough matter in space to be anything but a vacuum.

Jeff
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All opinions posted by me on Usenet News are mine, and mine alone.
These posts do not reflect the opinions of my family, friends,
employer, or any organization that I am a member of.
  #3  
Old December 14th 16, 10:05 PM posted to sci.space.history
David Spain
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Default Outer space

On 12/10/2016 6:26 PM, wrote:
If nature abhors a vacuum, why then is space pretty much a vacuum?Just got
thinking about it last night.

That's an old saying based on early experiments having to do with
entropy. Usually as applied when a vacuum chamber is exposed to a
pressurized chamber. As Jeff points out there is far more vacuum than
"non-empty" space-time, ie non-gravity well space-time. Thus it's fair
to say space-time or our Universe, *is* for any reasonable definition of
"is", a vacuum*.

However, there is some truth to it beyond the conventional wisdom, but
only in the quantum extreme. I suggest you Google the term "Zero Point
Energy" if you are not already familiar with that phrase.

Here's a reasonable starting point:

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

Also lookup the phrase "Casimir Effect" for further mind distortion. ;-)

Dave

*Speaking of gravity wells, for those fortunate enough to live in the
proximity of the center of a dense star cluster where spherical gaseous
formations are dense enough and hot enough but not too radioactive to
provide a livable atmosphere even for rocky bodies that are not
typically dense enough to hold their own atmosphere, the inhabitants of
such bodies might start out with a very different view of space-time,
until they developed telescopic techniques that would demonstrate
otherwise! What a shocker!
  #4  
Old December 17th 16, 08:42 PM posted to sci.space.history
Stuf4
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Default Outer space

DS: "non-gravity well space-time"

I am not aware of any part of the universe that qualifies as "non-gravity well space-time". Every point that I know of is under the effect of gravity..

The gravity well curvature is certainly a lot flatter out there in the vast expanses of nothingness (absence of matter). But it is not totally flat. There is still some curvature.

As for the scenario of being in the middle of a star cluster, that too is within a gravity well. And here you have a possibility of the gradient being locally flat, yet you are still deep inside the gravity well.

If anyone is having trouble picturing that, you can imagine two water wells.. Both are deep. Up a certain way from the bottom, the two merge into one so that at ground level (the top of the well) there is only one opening. The geometry where those two merge into one can look like a saddle. And this saddle will have a locally flat zone.

*This* is the type of thing you are referring to.

And here, Dave, is what I see to be another case of unclear communication.
Let's be perfectly clear that if any life were to evolve in such conditions, those life forms would be deep within a gravity well. Yes, a flat part of it. But still a well.

~ CT







From David Spain:
On 12/10/2016 6:26 PM, wrote:
If nature abhors a vacuum, why then is space pretty much a vacuum?Just got
thinking about it last night.

That's an old saying based on early experiments having to do with
entropy. Usually as applied when a vacuum chamber is exposed to a
pressurized chamber. As Jeff points out there is far more vacuum than
"non-empty" space-time, ie non-gravity well space-time. Thus it's fair
to say space-time or our Universe, *is* for any reasonable definition of
"is", a vacuum*.

However, there is some truth to it beyond the conventional wisdom, but
only in the quantum extreme. I suggest you Google the term "Zero Point
Energy" if you are not already familiar with that phrase.

Here's a reasonable starting point:

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

Also lookup the phrase "Casimir Effect" for further mind distortion. ;-)

Dave

*Speaking of gravity wells, for those fortunate enough to live in the
proximity of the center of a dense star cluster where spherical gaseous
formations are dense enough and hot enough but not too radioactive to
provide a livable atmosphere even for rocky bodies that are not
typically dense enough to hold their own atmosphere, the inhabitants of
such bodies might start out with a very different view of space-time,
until they developed telescopic techniques that would demonstrate
otherwise! What a shocker!


  #6  
Old December 17th 16, 09:02 PM posted to sci.space.history
Stuf4
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Posts: 535
Default Outer space

But I should also have stated that I agree with Dave's excellent point that when taken to the quantum extreme, there is this fascinating observation that where you thought there was nothing, you will find something.

Here this would be akin to renaming our planet Aqua, because you had applied your best logical reasoning. But then when you're investigating the ocean you find all these tiny bits of mud & sand floating around in some kind of colloidal suspension (solid within liquid). Then you'd scratch your head and muse that, "Hmm, perhaps there was some wisdom to calling it 'Earth' in the first place."

~ CT




On Saturday, December 17, 2016 at 2:50:43 PM UTC-6, Stuf4 wrote:
From wrote:
If nature abhors a vacuum, why then is space pretty much a vacuum?Just got
thinking about it last night.


Your observation is excellent.

The ubiquitous saying...
"Nature abhors a vacuum" is a crock of ****.

It is only those extremely rare severely isolated pieces of the universe where matter has lumped together that serve as exceptions to the accurate rule:

Nature love a vacuum so much that you might as well name our entire universe 'Hoover'.


This is somewhat akin to that scifi author who found fault with naming our planet 'Earth'. There is much more water on its surface than there is dirt. A more fitting name would be something like "Hydra" or "Aqua".


It is only from our human ego-centered perspectives that a name like 'Earth' is condoned. Also, only from that severely limited perspective can one spout a statement like "nature abhors a vacuum" and everyone buys into it as making any sense. It is a starkly humancentric hyper-limited expression of nature that this "rule" refers to.

~ CT

 




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