[Talking_Mouse]

Forgive a possible stupid question but the void between galaxies, was to my understanding, a void. How is this different than the void between galaxies?

[irv]

Forgive a possible stupid question but the void between galaxies, was to my understanding, a void. How is this different than the void between galaxies?

Actually, no. The halo surrounding galaxies has been found to extend much farther out from the main core than long thought. Relatively speaking, the density is much much lower than in the galactic body, but it's not a true void.

What they're talking about here is on a much more massive scale entirely. Deep sky surveys have shown that there's structure to galaxies. They clump in groups. And the groups also sort of form clumps that extend in great bands and filaments throughout the known universe (Maybe I should make that the "known" universe).

There have been voids seen between the galactic bands, but what's described here is mind-bogglingly huge. Whole galaxy clusters could disappear within it!

This is fascinating stuff

[Jedi Master Pikachu]

There are still gases, escaped planets, stars, moons, asteroids, other celestial bodies floating around in intergalactic space (mainly gas).

[Constantine XIII]

The gaps bigger than the distance between the Milky Way and Andromeda by something on the order of 1000 times, IIRC.

[dragnet2]

Forgive a possible stupid question but the void between galaxies, was to my understanding, a void. How is this different than the void between galaxies?

There is matter, dark matter and stars between galaxies.

[burzum]

Forgive a possible stupid question but the void between galaxies, was to my understanding, a void. How is this different than the void between galaxies?

Scale. Our galaxy is estimated to be about 100,000 light years in diameter and we have at least a dozen discovered satellite galaxies that range from 25,000 light years to 500,000 light years from out galactic center (and probably dozens undiscovered). Non-satellite galaxies in our Local Group range from about 1 to 5 million light years away. Our Local Group exists within the Virgo Supercluster which has a diameter of about 200 million light years. This consists of almost everything we see except with the most powerful telescopes (without a telescope you won't see galaxies further than about 2-3 million light years).

This void is estimated to have a diameter of about 1 billion light years. This is a void many multiples the size of the supercluster in which we reside. In fact it is significant in size of the Universe scales. If you take 78 billion light years as the lower bound of the diameter of the Universe, then you are talking about a half millionth the volume of the Universe.

One analogy is to think of a diffuse slowly expanding gas where molecules (galaxies) are on average 2 microns from each other. Then you find a 1,000 micron diameter void in this gas. This does not make sense. This find is large enough that it may make astronomers question the Cosmological Principle (that the Universe looks uniform anywhere you observe it). The extreme uniformity of the cosmic microwave background and photos like the Hubble Ultra Deep Field give powerful support to the Cosmological Principle. It will be interesting to see how this structure fits in. I would guess that it will make people reinterpret the Cosmological Principle to fit in better with the CMB observations that the Universe isn't 'perfectly' uniform (especially since the void was found by using the CMB to point the telescopes for an 'expected' gap).

[LibWhacker]

Clusters and superclusters of galaxies (and all the dark matter in the universe) tend to align themselves along "filaments" and "walls," leaving vast voids in between.

These structural voids (in the large-scale distribution of matter in the universe) are much larger than the space between adjacent galaxies.

Furthermore, these voids are thought to have been there since the Big Bang itself, and represent the distribution of matter and energy at the moment of the Big Bang (because if the voids had ever been filled with galaxies, it would've taken much longer than the age of the universe for the galaxies to vacate the voids, they are so big).

Here's a pic of one region of space that's about 500 million ly across. Each dot is a galaxy. The filaments are clearly visible. Astronomers have actually roughly mapped the whole visible universe and it's pretty much the same story everywhere. But I can't find that picture for you at the moment.

I think the largest voids they knew about up until this newest find are about 300 million ly across. So this new void is REALLY big. But they're all big.

[RightWhale]

How is this different than the void between galaxies?

It's not just the usual void between galaxies but a place where there are few galaxies and there would be the normal number of galaxies if they were distributed uniformly. It's big enough to contain several thousand or million galaxies but contains many fewer.