Is there a relationship between dark matter and anti-matter?

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Discussion Overview

The discussion revolves around the relationship between dark matter and antimatter, exploring theories related to dark matter detection, particularly through the OGLE micro-lensing project and the implications of cosmic microwave background (CMB) observations. Participants also touch on the status of various dark matter theories, including MACHOs and WIMPs.

Discussion Character

  • Exploratory
  • Debate/contested
  • Technical explanation

Main Points Raised

  • Some participants note that while the MACHOs theory has not been completely discounted, recent observations suggest insufficient density of normal matter to account for dark matter phenomena.
  • One participant asserts that CMB observations have effectively ruled out the MACHOs theory, as the CMB was emitted before compact objects could form.
  • Several participants question whether dark matter could be considered a form of antimatter, with one stating that antimatter has opposite electric charge properties compared to normal matter, while dark matter is characterized by having no electric charge.
  • There is a suggestion that while there may be a complex relationship between normal matter and antimatter, it is not straightforward and likely involves unknown physics.

Areas of Agreement / Disagreement

Participants express differing views on the status of the MACHOs theory and the nature of dark matter in relation to antimatter. No consensus is reached regarding the relationship between dark matter and antimatter.

Contextual Notes

Limitations include the dependence on observational data and the evolving nature of theories regarding dark matter and antimatter. Some assumptions about the properties of dark matter and antimatter remain unresolved.

Dade Murphy
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Hello,
I've been reading articles about the OGLE micro-lensing project, which started out looking to find dark matter as 'massive compact objects,' but now seems to have had more success finding exoplanets. Searching the forums here I couldn't find much recent discussion about theories of this sort, but a lot about the WIMP theory, which I understand is the most popular. Is it safe to say that the MACHOs theory is pretty well abandoned?

Thanks for your time,
 
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As far as I know this theory is not as yet completely discounted, however the most recent observations of the contents of the Universe seem to suggest that there simply isn't enough density of invisible 'normal matter', such as neutron stars and brown dwarfs to account for dark matter phenomena.
 
Dade Murphy said:
Hello,
I've been reading articles about the OGLE micro-lensing project, which started out looking to find dark matter as 'massive compact objects,' but now seems to have had more success finding exoplanets. Searching the forums here I couldn't find much recent discussion about theories of this sort, but a lot about the WIMP theory, which I understand is the most popular. Is it safe to say that the MACHOs theory is pretty well abandoned?

Thanks for your time,
Yes. CMB observations put the nail in that coffin, as the CMB was emitted before any compact objects would have formed, and the signature of dark matter in the CMB itself is very clear.
 
Chalnoth said:
CMB observations put the nail in that coffin,
Ah, thanks for updating me on that, I didn't know that CMB had finally laid that one to rest.
 
isn't dark matter just reflective matter just anti matter?
 
dirty dan said:
isn't dark matter just reflective matter just anti matter?
No, antimatter is something completely different. It would be best to ask any followup questions in a new thread - but only after you've read some of the many dark-matter threads we already have.
 
dirty dan said:
isn't dark matter just reflective matter just anti matter?
Anti-matter has all of the exact same properties of normal matter, except that its electric charge is opposite*. Dark matter has no electric charge at all, hence why it is dark. There's no reason to believe that normal matter and anti-matter are related in any sort of simple sense. There is surely a relationship between them, but chances are it's pretty complicated. It certainly involves physics we don't yet know.

* There's also a parity difference, but that is rarely relevant, and doesn't change the overall nature of the argument here.
 

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