How do we know that there is mostly matter in the universe?

[imported_Tick]

How can we tell that there aren't anti-matter galaxies out there?

 

[Idontcare]

"We cannot rule out the possibility that some antimatter star or galaxy exists somewhere," Share says. "Generally it would look the same as a matter star or galaxy to most of our instruments."

http://www.space.com/scienceas...matter_sun_030929.html

 

[SsupernovaE]

We REALLY don't know anything for sure. But based on our observations, if there are really anti-matter galaxies out there, then they are probably outside of our observable universe. Meaning they are either really really really far away, or in another dimension or parallel universe.

But cosmology suggests that for some reason when matter was created, there was slightly more matter than antimatter, so when they annihilated there was still some matter left over. The rest of the energy is converted into well, energy of some form.

 

[Idontcare]

Originally posted by: SsupernovaE
...if there are really anti-matter galaxies out there, then they are probably outside of our observable universe. Meaning they are either really really really far away, or in another dimension or parallel universe.

From where do you derive your statistics to arrive at the statement of assigning probability to the location of said anti-matter galaxies?

I know of no published data from which you could have calculated probabilities of the locations of anti-matter galaxies, inside or outside this universe. Do you?

 

[SsupernovaE]

Originally posted by: Idontcare

Originally posted by: SsupernovaE
...if there are really anti-matter galaxies out there, then they are probably outside of our observable universe. Meaning they are either really really really far away, or in another dimension or parallel universe.

From where do you derive your statistics to arrive at the statement of assigning probability to the location of said anti-matter galaxies?

I know of no published data from which you could have calculated probabilities of the locations of anti-matter galaxies, inside or outside this universe. Do you?

You're right. I shouldn't have said from observations, but rather from cosmology/Big Bang theory. The point I'm trying to make is that since the belief is most observable matter is regular matter, then any large collection of antimatter is unlikely. However, just like the article stated, we really don't know anything until we get out there and measure it. That would be one interesting expedition.

So, from theory (if you take modern cosmology at face value) the calculations indicate that regular matter is vastly dominant. The antimatter is speculated to have annihilated. If there is any left over, then according to theory, it's probably not in the vicinity of what we can observe.

 

[Biftheunderstudy]

Currently the presence of matter in the universe is understood to come as a result of CP violation in the inflationary era of the universe. More directly, the result of a non zero barionic number, meaning for every 10 000 000 000 matter/anti matter annihilations one particle of regular matter will be created. Our universe is thought to be that 1 billionth, the left overs so to speak.

Second, if there were large amounts of antimatter in the universe there would be boundaries where the matter and antimatter annihilated and there would be very obvious radiation coming from these boundaries. This does not rule out the possibility that there is antimatter out there in large quantities, only that we should be able to see it if there is.

 

[SsupernovaE]

Originally posted by: Biftheunderstudy
Currently the presence of matter in the universe is understood to come as a result of CP violation in the inflationary era of the universe. More directly, the result of a non zero barionic number, meaning for every 10 000 000 000 matter/anti matter annihilations one particle of regular matter will be created. Our universe is thought to be that 1 billionth, the left overs so to speak.

Second, if there were large amounts of antimatter in the universe there would be boundaries where the matter and antimatter annihilated and there would be very obvious radiation coming from these boundaries. This does not rule out the possibility that there is antimatter out there in large quantities, only that we should be able to see it if there is.

Right, so it is very unlikely that there are antimatter galaxies.

 

[Nathelion]

And no large annihilation events have been observed - if there were tons of the stuff out there, why haven't we ever seen it blow up? Again, it's likely that if it exists it is very far away/unobservable/in another dimension/etc....