Unveiling the Mystery of Antimatter in the Universe

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    Antimatter Universe
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Discussion Overview

The discussion centers on the nature of antimatter in the universe, exploring the composition of observable matter versus antimatter, methods of detection, and the implications of their interactions. It includes theoretical considerations and challenges regarding definitions and observations.

Discussion Character

  • Exploratory
  • Debate/contested
  • Conceptual clarification

Main Points Raised

  • Some participants question how physicists concluded that most of the observable universe is made of "normal" matter, noting that there is no observable difference between matter and antimatter.
  • One participant suggests that the distinction between "matter" and "antimatter" is arbitrary, similar to the assignment of "left" and "right," and that either could be labeled as such without a standard reference.
  • Another participant expresses confusion about the claim that the universe is predominantly made of protons and electrons, as opposed to antiprotons and positrons.
  • There is mention of a link to a resource discussing baryogenesis, which may provide further context on the matter-antimatter asymmetry.
  • Some participants note that if large amounts of antimatter existed, we would expect to see significant energy emissions from matter-antimatter interactions, which are not observed.
  • There is a discussion about the detection of antimatter, with some participants expressing uncertainty about methods other than annihilation, while others mention that antimatter can be identified through indirect means, such as charge and mass estimations.

Areas of Agreement / Disagreement

Participants express differing views on the definitions and implications of matter versus antimatter, with no consensus reached on the nature of their distinction or the methods of detection. The discussion remains unresolved regarding the broader implications of these concepts.

Contextual Notes

Some limitations include the lack of clarity on definitions of matter and antimatter, the dependence on observational evidence, and the unresolved nature of the methods for detecting antimatter in cosmic contexts.

Icebreaker
I'm told that most of the observable universe is made up of "normal" matter. How did physicists come to this conclusion? There is no difference between matter and antimatter when observed.
 
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This is the way I think and it might not be correct. The assignment of "matter" and "anti-matter" are arbitrary since we do not have a standard reference. We could simply call one of them "matter" and the other to be "anti-matter". This is similar in the situation to assign "left" and "right".


Kenneth
 
We do, which is exactly why I'm puzzled by the claim that the observable universe is made up of one type, the one of which you and I are made. i.e. protons and electrons, as opposed to antiprotons and positrons.
 
So it's just "chances are." I thought there was a way to detect antimatter (other than annihilation) that I was not aware of.
 
If there were large amounts of anti-matter in the universe, we would see enormous emissions of energy where they meet. Hellfire gave a link explaining that.
 
kenhcm said:
This is the way I think and it might not be correct. The assignment of "matter" and "anti-matter" are arbitrary since we do not have a standard reference. We could simply call one of them "matter" and the other to be "anti-matter". This is similar in the situation to assign "left" and "right".


Kenneth

One could, but it is certainly sensible to name the kind of matter that makes up 99.99999% of what you obserb matter and the rest anti-matter. It saves a heckuvalot of typing.
 
Icebreaker said:
I'm told that most of the observable universe is made up of "normal" matter. How did physicists come to this conclusion? There is no difference between matter and antimatter when observed.

Because we would expect to see fireworks at a matter-anti-matter horizon which we don't see. A mixed matter-anti-matter system is unstable.
 
Icebreaker said:
So it's just "chances are." I thought there was a way to detect antimatter (other than annihilation) that I was not aware of.
Observing at a distance, I can't think of any way of detecting antimatter (other than annihilation), except (possibly) rather indirectly. Up close & personal, antimatter particles reveal their 'true colours' in several ways other than by annihilation (e.g. estimates of charge and mass -> clean distinctions); however, this isn't much help, as all it does is tell you there is little anti-matter in cosmic rays (and none, to speak of, where spacecraft have ventured).
 

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