Dark matter comprises over 80% of the universe

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Discussion Overview

The discussion revolves around the nature and prevalence of dark matter in the universe, specifically addressing its composition, detectability, and the implications of its existence. Participants explore theoretical and conceptual aspects of dark matter, including its interactions and the challenges in observing it.

Discussion Character

  • Exploratory
  • Debate/contested
  • Conceptual clarification

Main Points Raised

  • Some participants assert that dark matter comprises over 80% of the universe, while others argue it constitutes about 27% of the mass-energy of the observable universe.
  • One participant explains that dark matter does not interact through fundamental forces except for gravity, allowing it to pass through normal matter without detection.
  • A participant questions the assumption that dark matter is flowing through us, expressing difficulty in reconciling this with its gravitational effects.
  • Another participant suggests that gravity is weak, implying that a significant amount of dark matter would be necessary for it to be felt.
  • There is a humorous exchange regarding the term "scadzillions," with participants debating its validity as a number.
  • One participant expresses skepticism about making assumptions regarding the presence of dark matter in everyday environments, noting that it appears to be concentrated around large astronomical objects.
  • A later reply introduces the idea of virtual particles and antimatter, suggesting that our understanding of the universe is incomplete and complex.
  • Another participant claims that determining the percentage of anything in the universe is impossible due to the lack of knowledge about what constitutes "one hundred percent."

Areas of Agreement / Disagreement

Participants express multiple competing views regarding the composition of dark matter and its detectability. The discussion remains unresolved, with differing opinions on the nature and implications of dark matter.

Contextual Notes

Participants highlight limitations in current understanding, including the dependence on definitions and the unresolved nature of certain concepts related to dark matter and its interactions.

Ameretsu
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Hello, all! I am no physicist, so please bear with me. I just read an article that stated that dark matter comprises over 80% of the universe. If this is true, why is it so hard to find? With that much stuff, you'd think we'd be swimming in it.
 
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Because dark matter does not interact through any of the fundamental forces except for gravity. Normal matter particles interact with other particles through gravitation, electromagnetism, the strong force, and the weak interaction. Without the latter 3, dark matter quite literally passes through everything else without being slowed. Even light just goes right on through it with no consequences. Since light doesn't bounce off of it or anything, we can't see it.

We could be swimming in it and you would never know.
 
Ameretsu said:
Hello, all! I am no physicist, so please bear with me. I just read an article that stated that dark matter comprises over 80% of the universe. If this is true, why is it so hard to find? With that much stuff, you'd think we'd be swimming in it.

Actually, Dark Matter comprises only about 27% of all the mass-energy of the observable universe. It is not so hard to find either. Read the below Wiki page and be sure to check on some of the references used for the original papers. You'll see it is fairly easy to find, just hard to know what it's made of.
See: http://en.wikipedia.org/wiki/Dark_matter#Galaxy_clusters_and_gravitational_lensing
 
Thank you for your reply.

So, that means that we cannot see, or feel dark matter in any way except by inference. May we assume that dark matter is then flowing through us? I find that concept a little hard to wrap my head around. I mean, if it is affected by gravity, shouldn't we be able to feel these particles in some way?
 
Ameretsu said:
Thank you for your reply.

So, that means that we cannot see, or feel dark matter in any way except by inference. May we assume that dark matter is then flowing through us?

Sure.

I find that concept a little hard to wrap my head around. I mean, if it is affected by gravity, shouldn't we be able to feel these particles in some way?

Gravity is very, very weak. It would take a LOT of dark matter in order for you to feel it.
 
Also, you have scadzillions of neutrino's passing through you every second and you don't feel them either, although I do think they make my throat a little dry from time to time. :smile:
 
Is scadzillions a real number, Phinds?
 
Drakkith said:
Is scadzillions a real number, Phinds?

It's certainly not a complex number. That would be ridiculous.
 
Drakkith said:
Is scadzillions a real number, Phinds?

Yes. It is 10 to the umpty upm. That's my story and I'm sticking with it.
 
  • #10
phinds said:
Yes. It is 10 to the umpty upm. That's my story and I'm sticking with it.

Ah, so 10^umpty^upm.
 
  • #11
Drakkith said:
Ah, so 10^umpty^upm.

no, 10^umpty-ump. That is, "umpty ump" is a singular phrase and its value is log base 10 of a scadzillion.
 
  • #12
So, that means that we cannot see, or feel dark matter in any way except by inference. May we assume that dark matter is then flowing through us?

I would not make such an assumption. It appears dark matter is at least located in the vicinity of large astronomical objects like galaxies and clusters of galaxies. Whether there is any between me and my computer screen is conjecture. Since 95% of the matter/energy in the universe has only been recently 'discovered' we probably should await some further knowledge before making some assumptions. And don't rule out 'virtual' particles and 'anti matter'...

Anti matter may have been consumed at the big bang such that scadzillions annihilated with 101 scadzillions of matter particles and our universe is a paltry leftover of real matter...'refuse' of creation. Add in virtual particles about which we do not have a complete understanding, which may also 'exist' all around us as quanta of non zero vacuum energy...well, whatever constitutes this universe, a lot seems way beyond most current science.
 
  • #13
There is no way to determine what percentage of anything occupies the universe since there is no way to know what the hundred percent is.
 

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