Is there really a Bizarro World?

September 26, 2006 12:33 PM

What is anti-matter?

According to this article, scientists have discovered that there are particles which travel back and forth between our "world" and the anti-matter "world."

I always figured that anti-matter worlds -- actual universes where there might be people, etc. -- were a conceit of sci-fi. I DO know that there is a real substance called anti-matter, but I don't have the physics to understand exactly what it is.

I gather that when the universe was formed, both matter (the stuff we, our houses, our chairs, our dogs, etc. are made of) and anti-matter (whatever THAT is) came into existence. And I get that when matter touches anti-matter, the two substances destroy each other. (I'm not sure why they do.) But how does all this tie into anti-matter worlds?

Is there another universe sitting "along side" ours?

posted by grumblebee to science & nature (14 comments total)

Well, to go the obvious first source:

After Dirac, science fiction writers produced myriad visions of antiworlds, antistars and antiuniverses, all made of antimatter, and it is still a common plot device; however, suppositions of the existence of a coeval, antimatter duplicate of this universe are not taken seriously in modern cosmology.

From wikipedia

Also of interest may be this article on the Many-worlds interpretation
posted by chrisamiller at 12:42 PM on September 26, 2006

The Chicago trib screwed up the story. Directly from Fermilab:

claim discovery of astonishingly rapid transitions between matter and antimatter: 3 trillion oscillations per second.

There are not "matter worlds" and "anti-matter worlds" that the particle moves between - the particle it self is sometimes matter, sometimes antimatter.
posted by MonkeySaltedNuts at 12:47 PM on September 26, 2006

What MonkeySaltedNuts said. Matter-antimatter mixing has been known for a long time. Most particles only differ from their antiparticle by a few quantum states and some by none at all (e.g. a photon is its own antiparticle) In certain situations a particle can actually oscillate back and forth between being itself and its own antiparticle. I believe (havent had time to study the results) that this is the first direct observation of this quantum-state mixing.

There are a LOT of mis-statements in that article.
posted by vacapinta at 12:53 PM on September 26, 2006

Antimatter isn't in a separate realm, so this particle isn't going back and forth between the two. It's basically matter that has certain things reversed compared to ordinary matter. For almost all purposes that something is charge. Sometimes you'll equivalently (see below) hear about it described as matter going back in time, but that doesn't mean antimatter eggs unbreak themselves or any other funniness. It's more a mathematical trick that you can use to describe it.

What they're almost certainly talking about is to do with certain relations between matter and antimatter. Basically, you should be able to reverse certain things in the laws of physics and get back to where you started - this is expressed as a symmetry. For example, CPT symmetry means that if you reverse charge (C), handedness (Parity) and time (T) you get laws of physics that look the same.

There are certain things that don't obey symmetries you'd otherwise expect them to. For instance, CP symmetry is violated by some particles (but for most particles this symmetry does work). Reverse charge and parity for them and it won't look quite like the same thing going back in time. See this wikipedia article. This B-whatever meson is doing some of this funniness. I don't quite get what this rapid transition business is all about, but this stuff will perhaps help explain why matter turned out to exist in slightly more quantity than antimatter - the mirroring of antimatter and matter is not perfect, and this meson is showing this imperfection up I guess.
posted by edd at 12:55 PM on September 26, 2006

Ah ok what vacapinta and MSN said. I have to admit that Fermilab article has me scratching my head a bit about exactly what this particle is supposed to be doing. But there you go.
posted by edd at 12:58 PM on September 26, 2006

Yes, ok, well I used that downtime just then to do more digging.

Here's the paper. It won't make a fat lot of sense to the layperson though.

The oscillation in question is more like neutrino oscillation, which your googlefu should help you brush up on. Still, B-mesons are important for the reasons I said. Just it has nothing to do with the stuff here :-)
posted by edd at 1:23 PM on September 26, 2006

Another bit to think about is that the universe appears to have a preponderance of matter. Various theories exist as to why there is more matter than antimatter.

However, since the two don't neatly separate by any convenient method, it's just not very likely that there's an antimatter planet out there orbiting about an antimatter sun busy fusing antihydrogen into antihelium.

Also, antimatter does not have negative gravity.

It's just not that exciting, and, due to conservation of baryon number (outside of anything that isn't the event horizon of a black hole), it's also really hard to make useful quantities of. It has a distressing tendency to destroy its container (not unlike plasma in hopeful fusion reactors).
posted by adipocere at 1:26 PM on September 26, 2006

it's just not very likely that there's an antimatter planet out there orbiting about an antimatter sun

Where IS the antimatter? Is it in our universe, or does our universe, by definition, only contain matter?
posted by grumblebee at 2:35 PM on September 26, 2006

What is antimatter? (from Space.com)
posted by blue_beetle at 2:42 PM on September 26, 2006

Is it in our universe, or does our universe, by definition, only contain matter?

It's in our universe. There is, ferinstance, often a ring of it being maintained at Fermilab in suburban Chicago..
posted by COBRA! at 2:44 PM on September 26, 2006

What we have here is a failure to communicate.

(Yes, this is the problem-- the world aches for better science writing, and for scientists who are better at talking to journalists. APS thinks so too. )

By the way, not only is it "unlikely" that there exists somewhere a (large) region of the universe that is made of antimatter instead of matter, there is in fact evidence against it. Antimatter is hard to keep around here because if you let an antimatter particle (e.g., a positron) near its matter partner (in the same example, an electron) they both turn into photons.

If there did exist somewhere a region of antimatter, the boundary between it and the matter regions would do the same thing- and we'd see these excess photons. We don't. (Can't find a popular science article about this, try your own googlefu and see what you get, or just read the abstract.).

Also of interest re: antimatter, "they" have managed to make anti-hydrogen!

I'd argue it's hard to make antimatter because it takes so much energy. We don't have any to start with, so you have to make it. Fermilab does it this way.

So, no, there does not exist a bizarro world full of antimatter- you'll have to get your bizarreness out of this one instead.

(BTW I am a physicist, but not *your* physicist, nor more importantly an expert in this area.)
posted by nat at 2:49 PM on September 26, 2006 [1 favorite]

Is the antimatter in our universe or not?
It's in our universe.

A side-note:
You may be getting confused if you have taken a philosophy course, or read some philosophy of the last 40 years or so, because philosophers talk about different "possible worlds". This does not have to do with matter and anti-matter, though. It has to do, most simply, with how to understand statements about "what might have happened if such-and-such".

Philosophers are interested in what makes statements true or false. For a statement like "the cat is on the mat" it's easy to tell what makes it true -- you just look at the mat, to see if the cat is there. But for a statement like "If I had never been born, my parents would be rich today", it's harder to tell what makes that true (or false, whichever it is). Some philosophers say that what makes it true (or false) is that there is another possible world (universe) where I WASN'T born... and if you "look" at that world, you see what would have happened, so you can tell whether the statement is true or not. But these other possible worlds are not actual, only our world is actual. (And again, this is not the same as matter vs. anti-matter.)
posted by LobsterMitten at 3:11 PM on September 26, 2006

Antimatter is regularly used in medical imaging. Those positrons are obtained from radioactive decay of unstable isotopes (which in turn are generated in a cyclotron).
posted by mr_roboto at 4:51 PM on September 26, 2006

It's basically matter that has certain things reversed compared to ordinary matter. For almost all purposes that something is charge.

When it comes to quarks, it's also colors. (Part of the theory of Quantum Chromodynamics.)
posted by Steven C. Den Beste at 12:03 AM on September 27, 2006