I’ve just read a brief book review, claiming that the Pentagon is trying to develop something called an “isomer bomb”.
Allegedly the size of a hand grenade, it supposedly would have a two kiloton yield.
The book review implies this is a boondoggle & that the research has been de-funded and re-funded several times.
As a degreed but not practicing chemist, the nomenclature makes my teeth itch. Generally isomers are molecular configurations with the same chemical composition: n-Butane & 2-methylpropane both have the molecular formula C4H10. Isotopes are atoms of the same element with different atomic weights (and thus often different half-lifes or other nuclear properties (like neutron capture cross-section or fissionability) – U235 vs U238. Allotropes are different stable crystal structures of a pure substance, Diamond vs. Graphite vs. Buckminsterfullerene.
Further brief reading via wikipedia shows that nuclear isomers are indeed “a thing”, analogous to an exited lasing medium, or phosphorescent/fluorescent chemicals (both involving metastable excited states of electrons and “forbidden” transitions to lower energy or even ground states). Still the term grates.
The term does at least originate in chemistry (Jöns Jacob Berzelius in 1830), so chemists feeling grated is more reasonable than for terms like “organic”.
I read that book, I think (Imaginary Weapons: A Journey Through the Pentagon’s Scientific Underworld - unless there’s a newer book on the subject). As I recall from that book, yeah, isomers exist with high energy density, but that doesn’t mean that you can get all the energy released in a useful way.
I read the same book, I think, and from what I recall, the problem wasn’t so much releasing the energy as creating the isomer. IIRC, producing enough hafnium isomer to manufacture that “hand grenade that can sink a battleship” that project boosters were touting would require a substantial portion of the output of the entire U.S. energy grid.
Because the entire point of DARPA is to avoid technological surprise by funding blue sky projects that don’t look practical by normal standards on the off-chance that one of them will occasionally achieve a break-through. It’s actually been a very successful R&D model.
But the downside is that DARPA winds up funding a lot of projects that wind up being busts. DARPA’s high risk, high reward approach means that most projects will be busts, but the idea is that the rare breakthroughs make it all worth it.
And, I Am Not A Physicist, but as I understand it, a halfnium isomer bomb isn’t theoretically impossible, and if it could be made practical, it really would be a total game changer - a hand grenade that could sink a battleship.
But, back to the downside, and again IANAP, but as I understand it, producing a halfnium isomer bomb goes beyond “we can’t quite figure out a practical way to do this yet” - even in theory it would require so much energy that if you could do it, the energy you’d be generating would be the breakthrough, and the halfnium isomer would be an afterthought. But a number of DARPA project managers have been seduced by the theoretical possibility of that hand grenade that can sink a battleship.
DARPA project managers and directors deliberately only have short terms of office precisely to avoid someone getting overly attached to a dead-end project and throwing good money after bad. The idea is to have a fresh set of eyes with no prior investment looking at every project every couple of years. But the downside is that sometimes those fresh sets of eyes just wind up getting seduced by the same pie-in-the-sky possibilities and don’t have enough time to get down into the weeds of all the projects they manage, especially the ones involving exotic physics they don’t really understand, and realize that it’s been a dead-end project with no real progress for years, and no plausible way forward.
In 1998, a group led by Carl Collins of the University of Texas at Dallas reported having successfully initiated such a trigger.
My goodness, Carl Collins. When I was graduating with a degree in physics from the University of Texas at Austin, one of my professors told me I should apply to the UTD graduate program because this guy Collins was working on some really promising, federally-funded gamma-ray-weapon research. I left physics instead, but it does seem like this guy knows where the money is.
I swear I read about this in some cheap spy novel in the 1960s. The material wasn’t hafnium (I think it was some sort of isotope of germanium) but it was supposed to be a handheld weapon with the ability to wipe out a city block. So, the idea goes back at least that far.
(That was before I was reading a cheap spy novel in the 1970s and suddenly thought, “Why don’t you just kill him?” - ending my relationship with the genre.)
This is, of course, the old idea of a “suitcase nuke”, where you get a good couple of kilotons from a device small and light enough to carry around. Such devices (in the form of tactical nuclear weapons) were indeed developed during the 1950s and 1960s.
Now, when engineering such a device so that it still fits within a briefcase (or artillery shell) there are various physical limitations, so it is a no-brainer that there has been research into alternative energetic materials for this purpose, besides the usual lump of U-233 or similar, starting well before the 1990s.
There are non-military uses for nuclear isomers, but, for sure, DARPA is one way to get your funding…
All quite true; I remember reading somewhere that the DARPA philosophy was that if they didn’t have a high failure rate, they were clearly doing it wrong and not being imaginative enough.
Just by way of a side comment, however, I wouldn’t regard the Arpanet as one of those risky far-out projects. By the time the Arpanet really started to grow in the 70s, Digital Equipment Corporation was already developing DECnet, a peer-to-peer network architecture for connecting the diverse computers of the DEC product line. By the time Arpanet adopted TCP/IP in 1983, the DECnet protocol stack was already in a mature Phase IV version, and Digital’s own internal DECnet-based global private network was the largest private computer network in the world. TCP/IP, the Arpanet, and DECnet were all developed in parallel.
So, although DARPA (sometimes called ARPA, and the names have switched back and forth over the years) has done some great things, and does deserve credit for pioneering the Internet, if they had not done it, others would have. Indeed, as recently as the early 90s, the International Organization for Standardization (ISO) had released approved standards for Open Systems Interconnect (OSI), which DECnet itself adopted in Phase V. It was the explosive growth of the TCP/IP based Internet that displaced and doomed OSI. Had it not done so, a different kind of Internet would have emerged out of OSI, and arguably would have been significantly superior, since OSI among many other things had a vastly bigger address space, more robust routing protocols, and better security.