# Two galaxies without dark matter - is this a big deal? **URL:** \ **Category:** Factual Questions\ **Created:** [April 23, 2019, 12:13am UTC](https://boards.straightdope.com/t/two-galaxies-without-dark-matter-is-this-a-big-deal/832916 "2019-04-23T00:13:43Z")\ **Posts on this page:** 7\ **Page:** 4
**Author:** ![Buck\_Godot](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/buck_godot/32/6573_2.png) [@Buck\_Godot](https://boards.straightdope.com/u/Buck_Godot)\ **Post date:** [April 26, 2019, 5:02pm UTC](https://boards.straightdope.com/t/two-galaxies-without-dark-matter-is-this-a-big-deal/832916/61 "2019-04-26T17:02:42Z")
For those in the know, am I correct in believing that these two galaxies indicate that the proportion of the matter in a galaxy that is dark is bi-model. That for most galaxies its 85% very something close to zero for a few, but with no galaxies with say 40% dark matter? ---
**Author:** ![Telperion](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/telperion/32/509_2.png) [@Telperion](https://boards.straightdope.com/u/Telperion)\ **Post date:** [April 26, 2019, 7:38pm UTC](https://boards.straightdope.com/t/two-galaxies-without-dark-matter-is-this-a-big-deal/832916/62 "2019-04-26T19:38:26Z")
> [@Buck\_Godot](#): > > For those in the know, am I correct in believing that these two galaxies indicate that the proportion of the matter in a galaxy that is dark is bi-model. That for most galaxies its 85% very something close to zero for a few, but with no galaxies with say 40% dark matter? I don’t think that necessarily follows. It could very well be that the distribution of dark matter is a lot less uniform than previously believed, and in that case we’d expect to discover all sorts of variations. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [April 26, 2019, 7:39pm UTC](https://boards.straightdope.com/t/two-galaxies-without-dark-matter-is-this-a-big-deal/832916/63 "2019-04-26T19:39:01Z")
I don’t think we can say. Before these two, any astronomer you asked would have said that all galaxies are mostly dark matter. Then we apparently found a couple of exceptions. There may well be other exceptions out there that we haven’t found yet, and who knows what proportions they’d have. ---
**Author:** ![ftg](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ftg/32/2801_2.png) [@ftg](https://boards.straightdope.com/u/ftg)\ **Post date:** [April 26, 2019, 9:28pm UTC](https://boards.straightdope.com/t/two-galaxies-without-dark-matter-is-this-a-big-deal/832916/64 "2019-04-26T21:28:31Z")
> [@Half\_Man\_Half\_Wit](#): > > The Bekenstein-Hawking bound, at least on the most straightforward interpretation, implies that any volume of spacetime contains a finite amount of information scaling with its surface area. Consequently, there’s only a finite number of possible configurations for each spacetime volume, and hence, in an infinite universe, we should (modulo problems of defining a suitable probability measure) expect each configuration to be repeated infinitely often. Hmm, this is quite interesting sounding. Going to have to do some reading and stuff. The part about scaling with surface area pings a few bells buried in the old deep memory. ---
**Author:** ![DPRK](https://avatars.discourse-cdn.com/v4/letter/d/4491bb/32.png) [@DPRK](https://boards.straightdope.com/u/DPRK)\ **Post date:** [April 26, 2019, 11:34pm UTC](https://boards.straightdope.com/t/two-galaxies-without-dark-matter-is-this-a-big-deal/832916/65 "2019-04-26T23:34:13Z")
> [@ftg](#): > > Hmm, this is quite interesting sounding. Going to have to do some reading and stuff. The part about scaling with surface area pings a few bells buried in the old deep memory. This sounds like the famous holographic principle (which arises from theoretical considerations, but AFAIK there is not yet any clear experimental evidence for it, nor do we definitely understand the internal workings of black holes). If true, it would mean that there is a maximal possible entropy for a finite region, which scales with the surface area. In any case, as far as regions being distinguishable at some scale to an observer or not, it shouldn’t matter what be _inside_ a black hole. ---
**Author:** ![Darren\_Garrison](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/darren_garrison/32/92_2.png) [@Darren\_Garrison](https://boards.straightdope.com/u/Darren_Garrison)\ **Post date:** [June 4, 2019, 6:13pm UTC](https://boards.straightdope.com/t/two-galaxies-without-dark-matter-is-this-a-big-deal/832916/66 "2019-06-04T18:13:17Z")
Update: [oops](https://www.slashgear.com/scientists-solve-the-mystery-of-a-galaxy-lacking-dark-matter-04579175/). ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [June 4, 2019, 7:36pm UTC](https://boards.straightdope.com/t/two-galaxies-without-dark-matter-is-this-a-big-deal/832916/67 "2019-06-04T19:36:23Z")
OK, then, that settles that. [Previous page](https://boards.straightdope.com/t/two-galaxies-without-dark-matter-is-this-a-big-deal/832916.md?page=3)