31 May 2009
What Dan Brown did for the Roman Catholic Church in "The Da Vinci Code" he did for our research on trapped antimatter in "Angels and Demons"
I traveled to Geneva, Switzerland in a 1986 mission to persuade CERN to let a few friends, students and me make an attempt to trap antimatter particles. (Years earlier I had failed to interest the US Fermilab in this project.) We called ourselves "TRAP" upon learning that CERN took seriously only teams with a name or acronym. The story of a young researcher, with no permanent position and no research funds, coaxing a disbelieving laboratory to let his tiny team try to trap a significant mass of antimatter for the first time still seems very compelling to me. Of course, it was my future that was at stake.
Never did I think or hope that we would not only trap and study antimatter, but that antimatter trapping would inspire a best selling novel and blockbuster Hollywood movie featuring trapped antimatter stolen from CERN. Never did I suspect that what Dan Brown would do for the Roman Catholic Church in "The Da Vinci Code" that he would do for my research work in "Angels and Demons."
Am I "rather pleased" about unexpected publicity as recently claimed in various recent reports?. "Amused" or "bemused" would be better descriptions. What I am pleased about is that CERN did finally give us access to antiprotons from its Low Energy Antiproton Ring (LEAR). I am very pleased that we were able to trap these antimatter particles and hold them for months, thereby demonstrating that we had a vacuum more than a million times better than what the best vacuum gauge could measure. I am also pleased that we developed methods to lower the energy of CERN's "low energy" antiprotons by more than ten orders of magnitude. I remain delighted that we were eventually able to report that the ratio of the charge and mass for the antiproton and proton had the same magnitude to the incredible accuracy of 9 parts in 1011.or better.
I am more than pleased, "awed" would be a better description, that CERN and physicists from many nations took my 1986 trapped antihydrogen dream so seriously. Shortly after we first trapped antiprotons, I proposed that we use our cold antiprotons to make cold antihydrogen atoms that could be trapped long enough to compare these antimatter atoms with ordinary hydrogen atoms.
CERN built us the "Antiproton Decelerator" as a cheaper replacement for LEAR, when they could no longer afford to keep LEAR operating. (CERN was not immune to the tremendous public interest in CERN generated by several fast hydrogen atoms that were observed in 1994, though such high speed atoms could not be used to precisely compare antimatter and matter atoms.) Physicists from many nations formed what are now four international collaborations (ATRAP, ALPHA, ASACUSA and AEGIS), all of who have adopted our methods to slow, trap and cool slow antiprotons as needed to form antihydrogen atoms.
ATRAP developed two methods that we hoped would make cold antihydrogen. In 2001 we made cold antiprotons and positrons interact at low energy in a device we call a "nested Penning trap." In 2002, both the ATRAP and ATHENA teams demonstrated that antihydrogen atoms were produced by this method. Again there was a lot of publicity. Later ATRAP also developed and demonstrated a rather different second method in which we used lasers to control antihydrogen production.
The dream of trapped antihydrogen atoms has not yet been realized, though our ATRAP team demonstrated in 2007 that we could produce antihydrogen atoms when a magnetic trap intended to trap antihydrogen atoms is in place. In 2008 the ALPHA team did the same. The ASACUSA team is about to try to produce their first antihydrogen, and to confine it (at least briefly) in a trap. We all, and a forth team just starting up, are working on new apparatus and methods to realize our antihydrogen dreams.
It would be unrealistic to expect that a work of science fiction such as Dan Brown's "Angels and Demons" would be scientifically accurate. Still it may be interesting to compare the account in the book and movie to the reality.
|In the book and movie the antimatter to be trapped is created using CERN's Large Hadron Collider (LHC)deep in a very long circular tunnel beneath Switzerland and France. The movie presents striking action shots of the LHC in operation.||False: In reality, the LHC has nothing whatever to do with the production of trapped antiprotons, of antihydrogen, or of trapped antihydrogen. Other, much smaller, machines at CERN produce antimatter in a form that can be trapped. The LHC is not even potentially useful for such production.|
|Antimatter must never touch its storage canister or the antimatter would annihilate (i.e. completely disappear) releasing energy.||True. Our antimatter traps use batteries and magnets to suspend antimatter in empty space. If the space is not empty, or the antimatter touches any wall, then the antimatter will annihilate. In this way we have stored antimatter particles for months.|
|Antimatter traps are portable devices that can be moved from Switzerland to the Vatican.||
True: We once used one of our antiproton traps to carry trapped particles from California to Boston, just to demonstrate that our traps were portable. (See report.) The trap was carried in a rented truck.
|Antimatter traps are small devices that can be easily snatched up and carried by a priest into a helicopter while powered by a tiny battery.||False: The good vacuum required to keep our antimatter particles from annihilating in collisions with matter atoms in the non-empty space requires that all antimatter traps are cooled to within a few degrees of absolute zero. The apparatus must thus either have a substantial refrigerator attached to it, or it must be within a substantial thermos bottle containing enough liquid helium to keep it cold. Traps for antimatter atoms require in addition a very substantial source of electrical current.|
|The 1/4 gram of trapped antimatter claimed in the book would be enough to blow up much of Rome. (A gram is roughly the mass of a paper clip.)||True: If all of 1/4 gram of antimatter would annihilate with 1/4 gram of matter, then the explosive power could be roughly the same as the Hiroshima nuclear bomb (if all of the mass converted into energy)..|
|It is possible to accumulate 1/4 gram of antimatter.||
Incredibly False: This is the huge fallacy of the book and movie. The most antimatter ever stored in a trap is about 10 million antiprotons. This is 10,000,000,000,000,000 = 1016 times less than what is claimed in the book. In fact, if all the antimatter particle every produced was annihilated at the same time there would not even be enough energy to boil a pot of tea. Oops! Folks in the Vatican would have been less terrified if they had studied a bit of science!
|Scientists wish to trap antimatter because it provides a promising solution to the world's energy shortage problem.||False: No antimatter energy source will ever be possible since it takes much more energy to make antimatter than can ever be recovered from antimatter annihilation. There is also no antimatter reserve awaiting our discovery since it would have long ago annihilated upon contacting surrounding matter. Our motivation for trapping antimatter is to study is basic properties and to compare them with the properties of ordinary hydrogen atoms.|
See also: Jeremy Hsu, "The Truth about Angels, Demons and Antimatter", LiveScience (copy)
Fox News (copy)
Yahoo News (copy)
The Harvard contribution to TRAP and ATRAP was supported by the United States NSF, AFOSR, and NIST.