Dark matter - maybe just water?

In summary, the missing matter in the universe cannot just be "hard to see", like cold gas or dark dust. It does not absorb or emit radiation, and is only detectable because of its interaction with gravity. Cold dark matter is thought to make up about 23% of the total matter in the universe, but we only know about it because of its gravitational interaction.
  • #1
nmk
1
0
Any reason why cold dark matter isn't just ice?

All the chemical reactions going on out there since the creation of the universe, would have created a great deal of water. Also would fit with comets being made of the same stuff.

Just wondering...

NMK
 
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  • #2
I have no idea what you're trying to say here
 
  • #3
nmk said:
Any reason why cold dark matter isn't just ice?

NMK
The missing matter isn't simply "hard to see", like cold gas or dark dust. Cold dark matter does not interact with EM radiation at all - it doesn't absorb it and it doesn't emit it (whereas water, or any other type of matter will). We only know it's there because of its interaction with gravity. It is not ordinary matter of any type we've seen before.
 
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  • #4
Actually nmk's is a good suggestion as to what the DM might be; but let us look at it.

If we ask what is the baryonic content of the universe is we come up with the cosmic relative abundance mix.

Basically the baryonic universe is made up of roughly 3/4 hydrogen, 1/4 helium and about 2% everything else by mass. Of the 2% everything else the most abundant elements are in this order: oxygen, carbon, neon and nitrogen.

Now helium and neon are inert so the most common compound in the universe is water, mainly either as ice or vapour because liquid water is very special and rare. That is why there is so much ice in the outer solar system making comets and such.

However, all we can have is therefore at most about 1/2% of the normal matter as ice, the rest is just mainly hydrogen and helium. That is why the gas giants are mainly composed of those elements.But it gets worse. There is a critical density in the standard General Relativity cosmology theory that the overall cosmological density of the universe is measured by, which is about 10-29 gms/cc.

The total density of the universe is believed in the standard model to have this density, or be slightly denser than this. The problem is the nucleosynthesis equations of the standard Big Bang model can only produce about 4% of this critical density. In other words the total baryonic density of the universe is limited to about 4% of the total.

Unfortunately we can see only about 0.3% of the total in the form of stars and emission nebulas.

So there is a lot of baryonic dark matter out there, over an order of magnitude greater than that which we can see, around 0.5% (of 4%) of this BDM could well be water - ice or vapour. So, although water may be the most common compound in the universe, the maximum amount of H2O that we can have is not a lot, only about 0.02% of the total!

Furthermore, as most of the baryonic DM is thinly distributed, most of the oxygen would not have had a chance to chemically combine with the hydrogen and so the actual amount of H2O is likely to be much less than this.

Note that, when we talk about DM we are normally referring to the unknown non-baryonic DM needed in the standard model to make up the masses of galaxies and galaxy clusters - about 23% of the total.

Finally of course the standard theory requires 73% of the total to be something else again, Dark Energy. You will find many threads and posts about both DM and DE in these Forums.

With this exotic DM and DE 96% of the total density of the universe is unknown in the standard model. Whatever it is it cannot be water!

Garth
 
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  • #5
DaveC426913 said:
The missing matter isn't simply "hard to see", like cold gas or dark dust. Cold dark matter does not interact with EM radiation at all - it doesn't absorb it and it doesn't emit it (whereas water, or any other type of matter will). We only know it's there because of its interaction with gravity. It is not ordinary matter of any type we've seen before.

I find it curious that because we now detect the presence of matter which does not interact with EM radiation, something otherwise never "seen" before, we jump to the assumption that it is non-barionic.

Just looking at history, before the detection of the neutron, the idea of a chargeless particle - a particle with only mass and magnetic moment - was unheard of. If it were possible to arrange barionic particles in such a way to create a structure which had no charge AND no magnetic moment, but was only detectable via it's gravitational interaction, how would we detect it on a micro scale as apposed to the current macro-scale dark matter observations today?
 
  • #6
I agree with the writer but in a different way which still poses a question. We have evidence of black holes emitting water vapor that is trace able in tiny amounts. Is it possible that dark matter is just this water vapor that had dispersed and is still prevalent but un-measureable from where we are at in science, exploration, and vision? maybe even the unseen gravity that holds it all together is indeed "water?"
 
  • #7
In a word, NO.
 
  • #8
it is the glue and universal solvent here, why not the universe where we can't even replicate the %s and grangers that the "blank" area represents?
 
  • #9
diver5154 said:
it is the glue and universal solvent here, why not the universe where we can't even replicate the %s and grangers that the "blank" area represents?

I don't have a CLUE what you just said, but I can tell you for sure that your previous post tells me that you REALLY need to read up on the basics.
 
  • #10
diver5154 said:
I agree with the writer but in a different way which still poses a question. We have evidence of black holes emitting water vapor that is trace able in tiny amounts. Is it possible that dark matter is just this water vapor that had dispersed and is still prevalent but un-measureable from where we are at in science, exploration, and vision? maybe even the unseen gravity that holds it all together is indeed "water?"

To have as big a gravitational effect as it does, dark matter must exist in very large quantities (we know how much). If it were cold dark matter, we would see it as clouds of gaseous matter. It would absorb starlight in bands according to its chemical makeup.

It does not do this.

(Astronomers do earn their paycheques. They do think of these things and do have reasons when they rule them out.:tongue:)
 

1. What is dark matter?

Dark matter is a hypothetical form of matter that does not interact with light or other forms of electromagnetic radiation, making it invisible to telescopes and other instruments used to detect normal matter. Its existence is inferred from its gravitational effects on visible matter, and it is thought to make up about 85% of the total matter in the universe.

2. How is dark matter related to water?

Dark matter and water are not related in any way. Dark matter is a theoretical concept in astrophysics, while water is a compound that is essential for life on Earth. The idea that dark matter could be just water is not supported by any scientific evidence.

3. If dark matter is just water, why can't we detect it?

If dark matter were just water, we would be able to detect it using telescopes and other instruments that are sensitive to electromagnetic radiation. However, dark matter is thought to be made of particles that do not interact with light, making it impossible to detect using traditional methods. This is one of the reasons why dark matter remains a mystery in the field of astrophysics.

4. How does dark matter affect the universe?

Dark matter is thought to play a crucial role in the formation and evolution of galaxies and other large-scale structures in the universe. Its gravitational effects influence the motion of stars and gas within galaxies, and it is also believed to be responsible for the observed bending of light from distant galaxies. Understanding the properties and behavior of dark matter is essential for understanding the overall structure and evolution of the universe.

5. Is there any evidence to support the idea that dark matter is just water?

No, there is currently no evidence to support the idea that dark matter is made of water. The existence and properties of dark matter are still being studied and debated by scientists, but the prevailing theory is that it is made of some as-yet-undiscovered particle that does not interact with light. The idea that dark matter could be just water is not taken seriously in the scientific community.

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