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kumar1988
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Suppose a galaxy out there was made entirely of anti-matter and never comes in contact with normal matter would be able to tell that it is made of anti-matter and not matter? If yes how would we do it?
kumar1988 said:Suppose a galaxy out there was made entirely of anti-matter and never comes in contact with normal matter would be able to tell that it is made of anti-matter and not matter? If yes how would we do it?
Vanadium 50 said:Chronos, there are limits to this. At sufficient distances, and we're talking at least tens of megaparsecs, this annihilation radiation is lost in the diffuse gamma ray and x-ray background. However, we also have some searches for anti-helium nuclei (produced in anti-stars) in cosmic rays to attempt to push this threshold out.
Nabeshin said:So an antimatter galaxy would look to us exactly the same as a matter galaxy.
Agreed, diffuse annihilations would be lost in the background noise at sufficiently large distance. But even an asteroid size intruder comprosed of ordinary matter would result in a detectable emission. Furthermore, if entire galaxies of antimatter do exist, rogue antimatter bodies [stars, asteroids, gas clouds, etc.] must also surely exist. The characteristic high energy gamma bursts that would result from collisions with their counterparts have not been observed.Vanadium 50 said:Chronos, there are limits to this. At sufficient distances, and we're talking at least tens of megaparsecs, this annihilation radiation is lost in the diffuse gamma ray and x-ray background. However, we also have some searches for anti-helium nuclei (produced in anti-stars) in cosmic rays to attempt to push this threshold out.
Maria76 said:A photon is its own antiparticle, so it's logical to think that a star and an antistar would be observationally indistinguishable. But I read somewhere (can't remember where) that antistars may be distinguishable from anti-stars by the polarization of their photons. So the polarization of gamma-rays emitted from supernovae would be somehow different than from anti-supernovae. Can anybody confirm if this is true?
granpa said:
Maria76 said:I found the following paper, which proposes that anti-stars can be distinguished from matter stars from the "polarization properties of their electromagnetic emissions" (see section 4.2).
http://arxiv.org/PS_cache/astro-ph/pdf/0405/0405417v3.pdf
unless, or course, gravitational time dilation (and shortening of measuring rods) is proportional to the absolute value of the strength of the field rather than to its potential. but that is another thread.Vanadium 50 said:The fact that the photon, which is its own antiparticle, falls at the same rate as ordinary matter conclusively excludes the possibility of antimatter being repelled from ordinary matter by gravity.
granpa said:unless, or course, gravitational time dilation (and shortening of measuring rods) is proportional to the absolute value of the strength of the field rather than to its potential. but that is another thread.
Brantoc said:The observed universe is matter, not antimatter. So no.. But..
One theory that is funny to think about, but in some ways I don't agree with basically states the universe was 50.00001% matter and 49.99999% anti-matter, over time they all destroyed each other and what is left is 0.00001% of the original matter. :) It was an early way of explaining the observed vs theory mass of the universe difference in the Big Bang. Now we just make up something and call it 'Dark Matter' and say "Don't bother testing for it, you can't." IMHO not very scientific, but no other explanations are currently forthcoming.
Like I said, funny to think about, and would make an interesting Sci-Fi book, but that is about all.
Anti-matter is the opposite of regular matter, with the same mass but opposite charge. For example, an anti-electron (or positron) has the same mass as an electron but a positive charge instead of a negative charge.
Anti-matter can be detected through its interactions with regular matter. When anti-matter and matter come into contact, they annihilate each other, producing high-energy particles that can be detected by specialized instruments.
Yes, anti-matter can be created artificially in particle accelerators. However, it is very difficult and expensive to produce and store anti-matter, so only small amounts have been created in laboratory settings.
Yes, anti-matter is present in our universe, but it is relatively rare compared to regular matter. This is because during the Big Bang, matter and anti-matter were created in equal amounts, but most of the anti-matter annihilated with matter, leaving behind the matter we see today.
While anti-matter has the potential to produce a large amount of energy through its annihilation with matter, it is currently not feasible to use it as an energy source due to the difficulty and cost of creating and storing it. Additionally, the process of creating and harnessing anti-matter would also produce large amounts of radiation, making it unsafe for practical use.