Black matter

[Michael Kieth Adams]

This would probably not explain the total mass of unseen matter but it might explain some of it.  Our universe is apparently about thirteen billion years old.  Almost every star that we examine seems to have planets.  How many stars have lived out their lives in thirteen billion years?  Every star that dies may leave one or more planets loose in the galaxy.  Huge masses of gas from dying stars  must be out there.  Also there must have been a huge amount of matter that never became stars.  Sub atomic particles that never became atoms should also be out there .  Anyone have a guess as to how much?  We’ve been looking for  strange exotic stuff but the unseen matter may just be universal leftovers from universe building processes.  Just another silly idea.  Mike

[robin_astro]

As you say most of the Baryonic matter in the universe is not in stars but as dust and gas in interstellar space (Not as planets though as they make up a very small fraction of the mass in a typical system).  Various techniques can be used to calculate or measure the total amount of Baryonic matter in the universe  and these appear to be converging on a consensus figure. See "the missing baryon problem" in Wikipedia for example

https://en.wikipedia.org/wiki/Missing_baryon_problem

This is well short of what is required to give the universe its critical density or explain the motion of galaxies though hence leading to the conclusion that there is a much larger fraction of as yet undefined non baryonic (dark) matter

Edited February 24 by robin_astro
clarity

[robin_astro]

Note that even finding more Baryonic (ordinary) matter would not solve the problem that the postulated (non baryonic) dark matter solves as dark matter would need  different properties to normal (Baryonic) matter to explain the various observations

 https://en.wikipedia.org/wiki/Dark_matter

Edited February 24 by robin_astro

[Michael Kieth Adams]

 

 

 

Baryonic matter, if I got it right, is essentially subatomic particles which are often unassembled atoms.  What makes the bits that they are made of come together?  Could they form clouds and have gravities effects?  How could they be detected?  I think about neutrinos, we barely know that they exist, what else is out there,  the movement of the galaxies tells us that there is something, maybe leftovers from universe building.

[robin_astro]

50 minutes ago, Michael Kieth Adams said:

Baryonic matter, if I got it right, is essentially subatomic particles which are often unassembled atoms

To a cosmologist, Baryonic matter is all normal matter (assembled or unassembled into larger structures like atoms) 

https://astronomy.swin.edu.au/cosmos/b/Baryonic+Matter

We know  how much of that stuff was created at the big bang and it agrees with the latest measurements of all that stuff now. 

Dark matter if it exists was proposed to solve a different problem.  It may be some exotic particle but it has to have different properties from the stuff we already know about and does not interact with it except through gravity

Edited February 24 by robin_astro
clarification

[robin_astro]

39 minutes ago, Michael Kieth Adams said:

 What makes the bits that they are made of come together?

https://home.cern/science/physics/standard-model

 

 

There are four fundamental forces at work in the universe: the strong force, the weak force, the electromagnetic force, and the gravitational force. They work over different ranges and have different strengths

[robin_astro]

The Wikipedia entry for Dark Matter pretty much covers what you are talking about. The current thinking on what it might be and alternative theories 

https://en.wikipedia.org/wiki/Dark_matter