What's the Straight Dope about "ultra-dense deuterium"?

I started hearing about this a couple of years back, in reports that scientists had created an ultra-dense form of deuterium. The subject came up again today in a report claiming that deuterium fusion in this form is aneutronic: http://www.gu.se/english/about_the_university/news-calendar/News_detail//small-scale-nuclear-fusion-may-be-a-new-energy-source.cid1323710

I’ve never seen an article explaining this supposed state in detail. I was wondering which category reports of it fall into:
[li]total asshattery[/li][li]a grossly over-exaggerated claim (i.e., scientists actually formed a single molecule of the stuff, which lasted a picosecond)[/li][li]an astounding discovery that will revolutionize physics very shortly.[/li][/ol]

I read that abstract as perhaps a poor translation into English, and “ultra-dense” being an unnecessary modifier to plain old “deuterium,” which, yes, is ultra-denser than plain hydrogen.

There is a thing called ultra-dense deuterium, which isn’t just describing that deuterium is heavier than hydrogen. I’m a little fuzzy on the physics of it, but apparently they start with deuterium and (uh, something, magic? I dunno… all I know is they aren’t just freezing it) and then voila! Ultra-dense deuterium. While I don’t know how they make it, the end result has the atoms packed in very tightly so that it ends up being, well, exactly what they said, ultra-dense deuterium, as opposed to normal deuterium where the atoms are spaced much farther apart.

The high density of it has applications in nuclear fusion, where the closely spaced atoms allow a fusion reaction to be more easily started using something like a laser to supply the initial input energy.

I was under the impression that they aren’t making huge quantities of ultra-dense deuterium yet and that what they are making is chunks of a few hundred atoms. I think what the article is referring to is that they are now thinking about using this as the basis of a small-scale nuclear reactor as the highly compact deuterium allows you to create and control a much smaller fusion reaction.

I imagine that a practical reactor is still 15 to 20 years away in the future, as it always has been and probably always will be. :stuck_out_tongue:

I’ve heard of atoms created with muons instead of electron orbitals. They would be “ultra dense” compared to regular atoms of that element, both because muons are more massive than electrons but also because their orbitals are much closer to the nucleus than electron orbitals.

But I don’t think they’re stable. Wiki says muons have a half-life of 2.2 microseconds, though that is for bare muons, and I’m not sure how being in an atomic system would affect their stability. Also, maybe they don’t need to be stable (I have zero knowledge of nuclear fusion other than “four hydrogens fuse to make helium in the sun’s core”). The abstract does mention muons, although as an output, not an input. I could be barking up the wrong tree here, but that’s my uneducated guess.

I’d say it’s between 1 and 2, probably closer to 1 on your scale.
There used to be a section on “ultradense deuterium” on Wikipedia, written by the same guy (Leif Holmlid) who appears in the article you linked to. You can read the discussion on the Talk pages: Talk:Deuterium - Wikipedia. Apparently, it’s the kind of stuff Holmlid has theorized to exist/dreamed up in this article (also by him!): Rydberg matter - Wikipedia.
He has also filed a patent claim: EP2680271A1 - Method and apparatus for generating energy through inertial confinement fusion - Google Patents.