Talk:Void (astronomy)

size

voids are approx size of superclusters, supervoids are approx size of walls... or so it seems? 70.51.11.219 (talk) 08:06, 2 August 2008 (UTC)

old list

A 1994 census lists a total of 27 supervoids with a distance of up to 740 Mpc.

#	Name	Distance (h-1Mpc)	Diameter (h-1Mpc)
1		134	88
2		207	96
3		216	72
4		241	86
5		129	92
6		236	72
7		248	100
8		201	76
9	Southern Local Supervoid	96	112
10		246	144
11		160	92
12		227	106
13		246	94
14		167	68
15		241	98
16		222	74
17		216	94
18		119	102
19		119	108
20	Boötes void (Great Void)	216	78
21		143	116
22		246	96
23		219	72
24	Northern Local Supervoid	61	104
25		198	74
26		246	80
27		241	70

Not shown in the above chart:

• Capricornus Void <---- that one has not been verified by any source other than a single webpage.
• The Eridanus Supervoid (Great Void), reported on 24 August 2007 by the NRAO from Very Large Array Sky Survey data, is much larger than these, being about 300 h^-1Mpc in diameter and 1800–3000 h^-1 Mpc distant. It also corresponds to a cold spot in the cosmic microwave background.

This was the original list on the page.

References

76.66.198.46 (talk) 12:28, 15 November 2008 (UTC)

Unit of distance

Mpc is a unit of distance so what does the h stand for in h^-1Mpc and why should that still be a unit of distance? I am tempted to remove any occurrence of h^-1 unless a definition is provided. —Preceding unsigned comment added by 90.195.11.112 (talk) 11:25, 24 August 2009 (UTC)

From [[1]],

Galactic distances are sometimes given in units of Mpc/h (as in "50/h Mpc"). h is a parameter in the range [0.5,0.75] reflecting the uncertainty in the value of the Hubble constant for the rate of expansion of the universe (h = H / (100 km/s/Mpc)). The Hubble constant becomes relevant when converting an observed redshift z into a distance using the formula d ≈ (c / H) × z (where c is the speed of light).

I'll change the "h^-1"s to "/h"s and link to the def.

Saintrain (talk) 12:48, 24 August 2009 (UTC)

hmm

Wonder if the voids have a black hole at their center. If that were true someone else would have thought of it and tried to check for any form of evidence. —Preceding unsigned comment added by 198.53.87.153 (talk) 00:19, 10 September 2009 (UTC)

I don't think so, matter appears to leave voids for concentrations of matter. If there were black holes, they would attract matter... ofcourse this is assuming extremely supermassive blackholes are what you're referring to. There are black holes in the voids because there are galaxies in the voids. Galaxies have stars, which produce stellar mass black holes. The galaxies themselves have supermassive central black holes. 76.66.196.139 (talk) 01:29, 21 September 2009 (UTC)

Could it be possible that one or more blackholes sucked in pretty much everything they could, and what is left is the stuff at the borders of the void that due to the expansion of space are moving away faster than the blackholes can pull at that distance? --TiagoTiago (talk) 21:17, 7 November 2011 (UTC)

If there was a supercluster mass blackhole in a void it would bend light and it would have a large gravitational lensing effect, which is not observed. Known dark matter is plotted in this diagram File:COSMOS 3D dark matter map.jpg but I cannot see how it aligns with voids or clusters. Graeme Bartlett (talk) 02:35, 8 November 2011 (UTC)

You should propose realistic scenarios. The only known way to make black holes is to stuff a lot of conventional matter together as in a galaxy. Such collapse is inefficient and will throw out a lot of stars and gas. That'd be easily visible. I think you have a fundamental misunderstanding of what gravity is. Gravity is a force field, not suction, and a black hole is not a giant vacuum cleaner. That means that a star falling in a gravity field will convert its gravitational potential energy into kinetic energy, speeding up. So, if it doesn't exactly hit the black hole (which is unlikely as it would take incredible aim), it will just speed past the black hole like a comet, then head back up the gravity well, losing kinetic energy as it slows down. So, no energy is actually lost anywhere, just converted from potential to kinetic energy and back. The only known way to lose the kinetic energy is to hit something on the way. That will release heat, in practice in the form of an accretion disc of a quasar. They are the brightest objects in the universe. --vuo (talk) 21:36, 29 August 2014 (UTC)

Additional info

From SIMBAD: [2] - a list of voids in the SIMBAD database, so we can construct a proper list article. 76.66.196.139 (talk) 01:29, 21 September 2009 (UTC)

This would be a good way to expand this article: arXiv:0912.3473

70.29.212.131 (talk) 07:01, 18 June 2010 (UTC)

Baryon acoustic oscillations

Vuo added this: "Voids were formed by baryon acoustic oscillations" with no citation. Surely this is only a hypothesis and not an accepted fact. How should this statement be qualified? Graeme Bartlett (talk) 08:21, 25 May 2011 (UTC)

History

This article only talks about what a void physically is and not about the history of a void. The history section could talk about how the idea of a void was first introduced by the atomists, turned down by Aristotle and then later accepted by Christaan Huygens and Evangelista Torricelli. I think adding this section would give the article more substance and make it more informational. What do you think? Chargerfan12 (talk) 00:50, 24 May 2013 (UTC)

Local Supervoid Update

According to recent reports the local supervoid is much larger than previously thought and may be the largest known object in the universe. 551 Mpc if my math is correct. Maybe this information should be added to this page or the list of voids?

References

Grizzlebizzle (talk) 09:32, 21 April 2015 (UTC)

Illustration of void

• 1617 print depicts nothingness prior to the universe
• Robert Fludd and His Images of The Divine

I thought that images from this work might work in this article. I do not have time to look into this just now, so I thought that I would make a note here. Blue Rasberry (talk) 19:58, 10 October 2017 (UTC)

Void (definion 2 - Astronomy): beyond the event horizon of this Universe and black holes where there is no space and no time

void: beyond the event horizon of this Universe and black holes where there is no space and no time. 2601:580:102:4DA8:D8CB:EB0A:EADC:FA44 (talk) 15:34, 11 July 2019 (UTC)

I'm not quite sure what you're asking for here. Do you want this article to include that definition? Where did you even get that definition from? Captain Eek ^{Edits Ho Cap'n!}⚓ 20:21, 11 July 2019 (UTC)

Another way of looking at voids (and dark matter)

The illustration of matter density in the article resembles detergent foam. With a foam all we see is the detergent but the main component (without which it could not exist) is the gas within each bubble or void. Is it possible that the voids are made of some form of dark matter exerting a force equivalent to negative gravity? Or, perhaps, they could be the home of a dark energy.

If we have some field or dark matter exerting a repulsive force on ordinary matter would we need massive dark matter at all? — Preceding unsigned comment added by Stan staveley (talk • contribs) 17:18, 26 December 2020 (UTC)

"first class" "second class" "third class"

calling things first, second, third class SHOULD technically be a descriptor of "well this is the first class of algorithms this is the second class, and so forth", but general english speech patterns have it that "first class " means BETTER than "second class" and "third class"

im pretty sure this article isn't trying to make a statement that any of those algorithms are somehow superior to the other 2600:6C47:A03F:C443:E534:BFCC:9963:7EBA (talk) 15:16, 22 August 2023 (UTC)