Talk:Intergalactic space

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I removed the following section only because it also appears in the interstellar medium article and was hence redundant:

==History==

Originally, astronomers thought that space was an empty vacuum. In 1913, Norwegian explorer and physicist Kristian Birkeland may have been the first to predict that space is not only a plasma, but also contains "dark matter". He wrote: "It seems to be a natural consequence of our points of view to assume that the whole of space is filled with electrons and flying electric ions of all kinds. We have assumed that each stellar system in evolutions throws off electric corpuscles into space. It does not seem unreasonable therefore to think that the greater part of the material masses in the universe is found, not in the solar systems or nebulae, but in "empty" space. (See "Polar Magnetic Phenomena and Terrella Experiments", in The Norwegian Aurora Polaris Expedition 1902-1903 (publ. 1913, p.720).

Mark Foskey 15:16, 20 October 2005 (UTC)

But is it redundant for someone visiting this article, but not the page on the interstellar medium? --Iantresman 15:54, 20 October 2005 (UTC)

Joshua, you removed an entired paragraph on the nature of intergalactic space, containing several pieces of information, but only queried one of them. Surely not even you requires a reference for EACH statement:

• Since the Intergalactic Medium is a plasma, it has the characteristics of a plasma.
• Even at the extremely low particle density,:

• it generates a magnetic field,
• is highly electrically conductive and
• will produce filamentation.

Your comment that the "IGM is actually dominated by voids which is hardly filamentation", I agree with, but the information in the removed paragraph never implied this. --Iantresman 16:38, 1 January 2006 (UTC)

The IGM is not filamentary. The superclusters form filamentary systems but if the stuff they leave behind is necessarily not filamentary. Please show a citation to a paper that states that the IGM is observed to be filamentary. --ScienceApologist 15:43, 2 January 2006 (UTC)

What's more because the IGM is so underdense and because conductivity is proportional to density then one could say it is hardly conductive at all. --ScienceApologist 15:45, 2 January 2006 (UTC)

While the current may be proportional to density, what is more important, is that the IGM is ionized. This fact alone, due to highly mobile electrons, makes it HIGHLY conductive. --Iantresman 20:08, 18 March 2006 (UTC)

[edit] Temperature.

Why do we assume that all of the IGM is warm to hot?

http://www.as.itb.ac.id/APRIM2005/abs_on_web/10018/10018.html

If hydrogen clouds can be cool enough to become molecular within the confines of a galaxy, why does it necessarily follow that it is in a plasma state between galaxies?

I think that it's inferred from radio astronomy. See Intergalactic plasma by Grote Reber (1986). See also, The X-Ray Emission of a Hot Dense Intergalactic Plasma by J. Bergeron (1970).

That doesn't mean that there are no cold clouds, only that some warm to hots clouds have been inferred. --Iantresman 21:24, 1 January 2006 (UTC)