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Antimatter and Antistars?
payndz asks: "I'm currently writing an SF novel, and came up with a weird thought for a piece of background flavour that, if there's any scientific basis for it, might get expanded into a larger element. The most up-to-date theories for the creation of the universe 13.7 billion years ago (give or take...) suggest that at the Big Bang, matter *and* antimatter were created. Over time, the fact that there was slightly more matter than antimatter means that mutual annihilation has left a universe of matter. (I'm not going to open up the whole can of 'dark matter' worms, unless somebody wants to...). I have a 'what if' question, which since Hubert Farnsworth isn't around I thought would get some good responses here: what if, rather than antimatter being annihilated by matter in the universe at large, there are 'clumps' of both matter and antimatter making up the universe? Since our clump is almost entirely matter, billions of LY away could there be galaxies made up of antimatter?More to the point, what physical properties would these galaxies have? Would a star made of antimatter function in the same way as a matter star, and would its emissions be made of antiparticles? Can you have anti-photons, and if you could, what impact would they have on any matter they illuminated? Could life evolve in an antimatter environment?"
Larry Niven had this great short story where Elephant looks for the most unusual piece of real estate in the known space... nicknamed "Cannonball", it is a solar system zooming *very fast* through our galaxy. While that is unusual by itself, it isn't the *most* unusual thing about it, as you can guess.
:-)
Luckily for him his pilot is a coward, so they don't land
Seriously, the existrance of large amount of anti matter (whole galaxies of it) isn't _that_ far fetched. Consider that the original big-bang universe is made out of hot plasma. A blob of matter pressed against a blob of anti matter will create a terribly violent reaction in the interface zone; this would act as a "wall" repelling both matter and anti-matter away from it, preserving them as seperate regions. Also, any electrical current flowing through the plasma will tend to separate matter and anti-matter. Given the whole universe is expanding madly in the duration it is possible that ant-matter "islands" survived.
AFAIK (IANAP) anti-matter galaxies/stars would be indistinguishible from normal-matter ones. Photons don;t care whether they are created by matter fusion or anti-matter fusion, etc.
"Since our clump is almost entirely matter, billions of LY away could there be galaxies made up of antimatter?More to the point, what physical properties would these galaxies have?"
One thing is for sure. There would be a person identical to you except they would have a goatee and no sleeves on their uniform.
First of all, there's basically no difference between a galaxy (or a physical body) made of matter and antimatter... Actually you wouldn't be able to tell. The major physical difference is the charge of particles (e.g. anti-electrons, or positrons, have +ve charge) but of course you wouldn't be able to tell since you would call +ve charge -ve and vice versa.
Secondly, according to the theories you mentioned, there's basically very little chance that large lumps of antimatter were formed during the big bang, since most of the annihilation would have taken place at a stage when all the matter was condended in a very small place, and therefore the distribution of antimatter would be quite uniform (so you wouldn't have a galaxy of am here and one of normal matter there).
Thirdly, there are no antiphotons. Photons are the antiparticles of themselves!
Hope it helps!
My Stack Overflow user
In this fundamental physics book, Feynman describes all of the states of physical matter and the laws of symmetry that go along with them. When discussing the right and left-handed rules, he asks the obvious question of whether they are arbitrarily chosen; whether right-handed means anything other than in opposition to left-handed. He asks this to spur our interest in discovering the basis for the symmetry of physical laws.
To illustrate, he imagines a conversation between a human and a distant alien, the purpose of which is for the human to communicate to the alien, after describing the human body and anything else of import, which hand is the left and which is the right, in order to know on which side to place the human heart. After dismissing a few possible physical phenomena by which this information could be conveyed, Feynman describes an instance (during a weak decay of a cobalt nucleus) in which the emitted electron always has a left angular momentum. This, he says, can be used to indicate to our alien friend which is left and which is right. Hold onto that for a second...
In the next section, he describes antimatter. He first theorizes that, other than annhilating each other on contact, objects made entirely of antimatter would not be noticeably different from those made of matter: It is one of the principles of the symmetry of physics, the equations seem to show, that if a clock, say, were made of matter on one hand, and then we made the same clock of antimatter, it would run in this (exact same) way. He then adds the example of the left-handed beta decay above by constructing a theoretical antimatter clock made of cobalt nuclei. He speculates that since left and right-handed matter clocks could be constructed to behave differently, thus violating the law of mirror symmetry, that antimatter clocks would also behave dissimilarly depending upon their handedness.
He goes through all of that to simply tell us that a left-handed matter clock is equivalent in every way to a right-handed antimatter clock. Unfortunately for sci-fi novelists, changing matter to antimatter merely alters the handedness of the particles, rather than actually violating symmetry or having any other noticeable effect. Of course, his lectures are no longer cutting-edge and the book only gives a laymans description of the underlying physics, but it doesn't look too good.
Feynman ends up concluding:
"I assumed blithely that there were no elves out there in the darkness"
Seriously, some recent Ask Slashdot's have been ridiculous - doesn't anyone know how to use Google, etc anymore?
This one takes the biscuit though. You're a writer (or want to be) - at the very least you should be able to do your own research for your work!
Posting an Ask Slashdot is a very bad idea, for at least two reasons:
1. There's no way you can easily distinguish between accurate and inaccurate statements.
Just because something quotes a scientist or it's been modded up it doesn't make it any more reliable then anything else.
2. You leave yourself open to litigation.
George Lucas makes a point of not looking at Star Wars fan fiction because he doesn't want to leave himself vulnerable to the guy who'll scream "Hey, you stole that scene/character/whatever in Episode III from my story!". You might not have billions to lose but by canvassing for information and ideas so publicly you're still leaving yourself wide open to that sort of allegation.
You might think that Slashdot is an open forum, populated by open source advocates who would all be opposed to intellectual property litigation and would do nothing more than help out and wish you luck but it'll only take one asshole to prove you wrong.
Someone's bound to mod this down as flamebait or as a troll but if you're going to be an author then you can't afford to ignore this stuff.
"Accept that some days you are the pigeon, and some days you are the statue." - David Brent, Wernham Hogg
Just don't put the pasta near the anti pasta. That could be bad.
/rimshot
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ping -f 255.255.255.255 # if only
But he isn't writing a fantasy, he is writing science fiction. Therefore, his "constraints" are valid, since they are what define the genre.
Actually, the thing that matters in scifi is consistency. You can make up the rules, but once you have you have to stick to them, otherwise your stories disintegrate into deus ex machina handwaving. That is why Star Trek is bad scifi* - the capabilities of all its technological artifacts change from episode to episode, and they can always "technobabble" their way out of any situation. In Star Trek, technology is indistinguishable from magic. Far, far better is the work of Alastair Reynolds - he does use technologies which don't yet exist, but his characters are forced to work within fixed limitations (i.e. humans colonize the nearby stars relying on relativistic time dilation and suspended animation - there is no FTL, and anyone who tries it fails, no matter how useful it might be for the story).
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* However it can be good drama, it's not scifi even tho' it's in space.
There are a few differences between an antimatter galaxy and a matter galaxy like our own. For instance, in an antimatter galaxy, the element Antimony is called "Mony". They use it as a means of facilitating the exchange of goods and services. Also, in antimatter England, they drive on the right side of the road.
Observation of annihilation gamma rays places strong constraints on the amount of antimatter in the universe. For example, we can confidently say that most of this galaxy is normal matter. Were this not the case, annihilation of matter and antimatter gas in interstellar space would produce too much annihilation radiation at 511 keV (electron/positron annihilation) and at ~100 MeV (photons from neutral pion decay.)
IIRC, the smallest scale at which antimatter can dominate is galactic superclusters, but even that may now be ruled out.