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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.
It has been done before, about a million times in one form or another. Somhow this article triggered some Startrek flashback...
A problem cannot be solved at the same level of awareness that created it.
There's a Larry Niven short story called Flatlander which deals with the concept of antimatter stellar objects - only briefly, but it's worth a read.
Also, wander up to your nearest university and look up the astro-physics department. Chances are there'll be a couple of knowledgable types in there who could point you in the right direction.
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Here be Dragons
"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
But he isn't writing a fantasy, he is writing science fiction. Therefore, his "constraints" are valid, since they are what define the genre. For example, writing about a flat earth should not be considered true science fiction, for the simple reason that it is quite unlikely that the earth is flat. Standard scientific opinion is that the earth is round. While it is true that much of astrophysics is "theory," it is educated theory.
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"
Which ignorant asshole modded him up? He doesn't have a clue what he's on about. Anti-photons *are* photons.
The equations that describe matter and anti-matter have identical solutions for the case of photons, meaning that anti-photons and photons are the exact same thing. This is logical since if they were not then what would photons and anti-photons react to create?
we don't see anti-matter photons hitting our telescopes, therefore anti-matter stars do no exist...
I'm pretty sure that a photon from a matter-antimatter reaction is the same as a regular photon, and that gamma radiation from said reaction is just regular gamma radiation also, not "anti-gamma". Therefore, I don't think anti-hydrogen fusion is going to be that different from regular hydrogen fusion. I don't think you would be able to tell the difference between a matter and an antimatter star just by looking at it, you'd have to get close enough (or observe something made of matter that got close enough) to get caught in its solar wind (anti-hydrogen is definitely different from regular hydrogen, see).
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
The anti particle of a Photon is a photon. However if you had an anti-mater star, it would probably be blindingly obvious. Stars emit photons, but they also blow off a stellar wind of other particles (electrons, protons etc) If it was an anti star as soon as this stuff hit the intersteller media (that loose collection of hydrogen and other stuff between the stars) it would react in a stream of gamma rays around the star.
Erlang Developer and podcaster
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.
it doesn't REALLY matter if theres some sillyness from physics point of view(hyperjump is one) as far as the book tells a good story and is intresting otherwise, has good flow of text and other things that make a book a great book. keep the sillyness logical and constant though, _DON'T_ fall into explaining every little tidbit how it works and how it is possible unless it's essential from viewpoint of some character in the book(or similar).
most great scifi books/ short novels could have been just as easily setted in non typical scifi setting(heinleins starship troopers could be set without much fuss into ancient greek), bad scifi is where the 'scifi' is used just to cover up something else, like the lack of plot or bad writing. though, one can use the story to tell of a world to come and it can work pretty well, and predict possibilities of technology, but without good storytelling these are just academical papers on possible future.
and most things that apply to scifi apply to fantasy too, mostly because underneath they are pretty much the same for most authors, it doesn't really matter if the lockpick is a complicated electronic hacker gadget or a spell, or if you use a robot instead of a demigod as an ageless being watching over humanity for thousands of years.
world was created 5 seconds before this post as it is.
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.
See, empty space isn't really empty. There's Hydrogen out there. There would be an amazing light show at the border. The constant meeting of matter and anti-matter (space dust, if you will, emitted by both galaxies) would most likely be very visible. Matter/anti-matter reactions are very energetic, far more so than fusion, even.
The only way to have anti-matter galaxies in your universe is if they were more than 13.7 billion light years distant, so the light from the interface hasn't reached us yet. Or maybe there could be a single anti-matter galaxy somewhere out there, discovered by the weird light reaching us from that corner of the universe. I doubt our telescopes have looked everywhere, yet.
Aside from all that, science is just a hook. As long as you're internally consistent, it doesn't matter if your science is far-fetched. Plot, characters, story. Interesting things happening to interesting people will be what sell books. I probably didn't need to tell you that. I still read a lot of old sci-fi that has bad science in it. 'Lensmen', Heinlein juveniles like 'Tunnel in the Sky', 'Citizen of the Galaxy', and 'Starman Jones', Campbell's 'Arcot, Morey, and Wade' stories. Love that stuff.
In Anvil of Stars, Bear introduces a civilization so advanced that they could manipulate vast ammounts of matter over large distances and convert M objects to A-M. Including people. The human's who were converted to A-M died slowly because their organic chemistry was subtly different. Made for a nasty suprise when the pilots tried to re-dock with their mother ship.
Not that this represents anything based in reality or the laws of physics. Just "prior art" from a respected hard sci-fi writer.
meh.
Here's something to think about that follows: light emitted by antimatter, because the electric and magnetic fields are generated in reverse, would be inverted in frequency/wavelength.
I have no idea what you mean by "inverted in frequency/wavelength." However, the truth is that light would be perceptibly unaffected. As correctly noted by several people here, the photon is its own antiparticle. Or, if you wish to think in terms of E-M waves, changing the sign of the E- and B-fields in an electromagnetic wave is simply equivalent to a 180-degree phase change (remember those sin/cos waves), which we wouldn't notice.
Would antimatter tend to absorb high-frequency light (uber-ultra-violet) and permit low-frequency (infrared) to pass through, rather than the reverse with matter?
We don't have a whole lot of experience at this point studying the atomic structure of anti-atoms. However, there's nothing at this point to cause one to expect that their atomic physics would be dramatically different from theoretical expectation: that they'd be the same as regular atoms.
Why doesn't anyone consider 'Ask Slashdot' to be reasearch?
Seems like you're the only one around here crufty enough to think it isn't. Most people have been giving lucid, well-thought out responses. Then there's the "I don't like this question, so I'll bitch" troll. Come on, whine a little more about ask slashdot! You can do it!
Wow are there a lot of whiney people on slashdot.
"Ignorance more frequently begets confidence than does knowledge"
- Charles Darwin
As for Point Two ... unless 1) somebody posts detailed plot, story, or character information here, 2) you are dumb enough to include it in your book, and 3) your book is lucky enough to make it into print after you include unsolicited fan fiction in it, you should be fine. The SF writing community trades research all the time; you can see it in action over on the SFF.net or Speculations research topics.
I think it's a fine idea for people to solicit ideas on slashdot. It is an open forum, and many of the popular posts express sympathy for the free expression of ideas.
I wish more people would do so. I don't look forward to a society where everyone is afraid to ask questions in public for fear of being sued.
You're Dubya's speech writer, aren't you???
I was about to argue this point but I just read it again slowly and see now that it is technically correct. You can't tell the difference from the outside. However just because some form of matter passes that point which we call the event horizon doesn't mean that anything magical happens to it. I read just recently that someone, Hawking I think, proved that if you fell into a blackhole you couldn't tell when you had passed the event horizon. So just because you couldn't tell from the outside whether a blackhole is matter or anti-matter doesn't mean that there couldn't be a difference. But maybe there isn't. Maybe it all gets squeezed into a quark soup.
It's not just mass which distorts space-time and creates the appearance of gravity. Energy can do the exact same thing.
Okay this is news to me. I would like to see references for this. It has been a few years for me as well but I was taught that energy, such as a light beam, will follow the space time curvature, but does not by itself cause any curvature. If you know the name of the governing equation that relates gravitational force to electromagnetic energy density please tell me because I would be fascinated to read about it.
Just to be sure I understand you right; In a hypothetical universe with only two particles forever orbiting each other, if a beam of light suddenly shone between them then they would slowly approach each other in a tighter orbit until finally they touched? Is this right? Although this makes intuitive sense I am pretty sure it contradicts what I have always been told.