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How do astronomers know that there are no antimatter galaxies?

Antimatter stars would look the same as stars made of matter. Material from one cluster of galaxies doesn't interact with othet clusters. Could there be equal numbers of matter galaxies and antimatter galaxies?

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  • 2 years ago
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    >> Material from one cluster of galaxies doesn't interact with othet clusters.

    That's not true. There has to be some place between any two adjacent clusters, where the material from one cluster meets the material from the other cluster. The space between clusters is not a perfect vacuum, it has about 1 hydrogen atom per cubic meter. Some of these atoms collide with each other. If one was regular matter and one was anti-matter, the collision would produce a lot of energy. The total effect would be a hot region between the clusters, and we don't see that.

    Another argument is that neutrinos from supernovas spread out all over the universe. Our detectors on Earth don't find any abnormal number of anti-neutrinos.

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  • 2 years ago

    It has never been witnessed, but Matter and Antimatter have a detrimental effect on each other

    A bit like Good and Evil

    When they meet each other is destroyed

    When the Big Bang happened, it is thought that Matter won the battle

    Could even have been by a a single Particle which was energised enough to start it

    I joke that it was a Quark of Fate ha ha

    For all we know, our whole Uniniverse could be contained within a single Atom

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  • 2 years ago
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  • 2 years ago

    All of the galaxies of the observable Universe are thought to consist of ordinary matter. As it was explained to me, the best evidence for this is the study of "cosmic rays", which are high energy atomic nuclei that hit Earth continually at speeds that are very close to c, or light speed. They are composed mostly of protons and alpha particles, but with an occasional Iron or Calcium or Silicon nucleus, etc. They are thought to come from the Universe at large, meaning from all of the galaxies in the Universe. If say half of all galaxies were composed of antimatter, then half of all cosmic rays should also be composed of antimatter. Yet they are not. They are all regular matter.

    The fact that our Universe is essentially 100% ordinary baryonic matter and not a 50-50 mix of matter-antimatter is one of the great quandaries of modern Physics. No one has a good answer to explain this.

    Source(s): The great Physicist Richard Feynman observed that a proton traveling forward in time is absolutely equivalent to an antiproton traveling backwards in time. Maybe all of the antimatter galaxies set off traveling backwards in time at the instant of the Big Bang? Sorry, just a thought.
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  • someg
    Lv 6
    2 years ago

    They don't know anything. They just push the buttons we engineers tell them to push when we tell them to.

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  • Dixon
    Lv 7
    2 years ago

    Statistics. Since everything we have ever encountered above the nano scale is matter, and the early universe was highly homogeneous, it is stupendously unlikely for a large region to be formed of the non dominant matter type.

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  • 2 years ago

    Possible

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  • 2 years ago

    I asked a very similar question a few years back - do anti-matter black holes exist? The answer is, it’s *possible*, but not very probable. It’s more likely that all the antimatter was annihilated by the existing matter shortly after matter and anti-matter formed; but there was a tiny bit *more* of matter - which still exists...

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  • neb
    Lv 7
    2 years ago

    Well, good question.

    I would guess there are two main reasons. The first reason would be the absence of a mechanism that would separate antimatter and matter into large clumps. One would expect that since we seee matter and antimatter created at the same time in all of our experiments, they should be tightly coupled with each other and annihilate quickly.

    From the above, the second argument is that it would imply continuous interaction which should produce a lot of gamma radiation which we don’t seem to see.

    The current ‘thinking’ is there is a slight asymmetry between matter and antimatter that ‘favors’ matter albeit slightly. Nobody is really satisfied that we have an explanation though.

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    • cosmo
      Lv 7
      2 years agoReport

      Yeah, Alfven-Klein was pretty cool back in the 1960s, but lack of detectable annihilation photons means that nowadays it's on the scrapheap of scientific history, promoted only by a tinfoil-hat crowd who believe that matter domination is somehow unfair.

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