I was at a very interesting event in Dublin yesterday evening; an informal panel discussion for the public on ‘Angels, Demons and Antimatter’ hosted by the Royal Irish Academy and The Irish Times. It’s great to see the Academy hosting this sort of event as it helps to bridge the gap between science and the humanities (the ‘two cultures’ famously described by C.P. Snow).
The event was ably chaired by Dick Ahlstrom, veteran science editor ofThe Irish Times, and the panel boasted four heavy hitters from the world of particles physics: Alex Montwill, Ireland’s best-known particle physicist and renowned communicator of science: Ronan Mc Nulty, leader of the experimental particle physics group at UCD, a group that have a major involvement with the LHCb antimatter experiment at CERN: Tara Shears, lecturer in physics at Liverpool University, also heavily involved in the LHCb experiment: and Paul Bowe, the Irish physicist who is technical director of ALPHA, the anti-Hydrogen experiment at CERN.
In his introduction to the event, Dick Ahlstrom sensibly asked the audience how many had seen the film – only about a third, which confirmed my view that people are interested in particle physics for its own sake, film or no film. Tara Shears then kicked off with a pithy summary of the film, explaining that a ticking bomb made of antimatter provides the timeline of the unfolding story. Then it was over to Alex to give a brief introduction to the phenomenon of antimatter. He did this in exemplary fashion, starting with the prediction of antimatter from the Dirac equation (…“Dirac was not the sort of scientist to brush extra solutions that seemed to have no corresponding physical reality under the carpet“) and proceeding to the experimental discovery of the positron in 1932 (if you want details on the discovery of antimatter, see post here). The discussion then honed in on the nature of antimatter, how it occurs in nature and how it is produced in minicscule amounts in high-energy accelerators.
The panel then turned to one of the great mysteries of physics – why is our universe primarily made of matter and not antimatter? Ronan gave a brief overview of charge symmetry, parity symmetry, charge-parity (CP) violation and the Sakharov conditions ; these are three conditions that theory predicts must have existed in the early universe for the current asymmetry of matter and antimatter to develop.
Charge and parity operations: note that the final quadrant is not identical to the first
This led nicely to a discussion of the relevance of high-energy physics to cosmology. I was very pleased this came up, as it is not always obvious to the public that, as well as studying the fudamental nature of matter, high energy accelerators offer a direct glimpse of the very early universe by recreating the energy conditions that existed shortly after the big bang (a point that is often missed by critics of the big bang model).
Paul Bowe then discussed the production of anti-hydrogen at CERN (an atom of anti-hydrogen simply comprises an anti-electron orbiting an antiproton, see previous post on this). He gave a brief overview of the ALPHA experiment – the production of positrons, the production of antiprotons, the mixing trap etc.
Schematic of hydrogen and anti-hydrogen atom
A picture of the experiment reminded me that while I find the discoveries of particle physics fascinating, I’m happy to leave the experiments to others!
Image of ALPHA experiment
Paul also addressed a question I was asked a while ago – Do we expect the spectrum of anti-H to be the same as that of H? If I have understood correctly, the answer is yes (since the electromagnetic interaction between the anti-proton and the positron should mirror that between the proton and the electron). If not, the spectrum of anti-H will have major implications for our understanding of CP violation.
The second part of the discussion dealt with Hollywood’s take on antimatter in Angels and Demons. It started with a clip from the film, the scene where Dr Vetra tries to explain to the destructive potential of the antimatter bomb to the authorities, advising that they evacuate the Vatican city forthwith.
Of course, the panel were quick to point out the unfeasability of the bomb, as mentioned in the post below: because of the difficulties of creating even a few atoms of antimatter in particle accelerators, it is simply not possible to create a bomb made of antimatter (or to use it as an energy source). And if such a bomb could be made, the trap container would be gigantic, not the little package portrayed in the film. However, I was pleased to hear that Tara (and I think the panel as a whole) felt Brown’s plot was acceptable cinematic license and made for a good story.
A small container for an antimatter bomb?
In keeping with the informal nature of the event, there was a lengthy question and answer session after the panel discussion. Some interesting questions were;
1. Is it possible there is plenty of antimatter in our universe today, in the form of distant galaxies made of antimatter?
I think the answer was that this is a real possibilty, but a basic asymmetry between matter and antimatter is still implied.
2. Does the neutron have an antiparticle?
Yes, because the neutron is a composite particle – the anti-neutron is made up of anti-quarks etc). Ronan pointed out that the question Does the neutrino has an antiparticle? is much more interesting and the subject of much debate.
3. What is the relation between antimatter and dark matter?
None – dark matter is the name we give to matter that has a gravitational effect but does not interact with the electromagnetic force. However, whatever particles make up dark matter presumably have anti-particle counterparts!
4. My question: Why did Dan Brown choose to introduce the topic of antimatter to the story at all, wouldn’t TNT have done?
My own view is that he was anxious to include cutting edge science, as the relation between religion and emerging science is a major theme of the novel. However, Tara had a better answer: novelists write about what they find interesting and Brown happens to be interested in particle physics! Apparently, he even visited CERN in 1990. QED.
All in all, this was a very interesting an informative event, a treat for anyone interested in particle physics or indeed are the public perception of physics. If there was one sour note during the evening, it was Dick Ahlstrom’s observation that “ the UCD contribution to the LHCb experiment really occurs through the back door” as Ireland is not a member of CERN. This is a sad situation that we have touched on many times before, so I’ll leave it for now. As for Dan Brown, long may he continue to include science in his bestselling novels.
9 responses to “Antimatter at the Royal Irish Academy”
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Thanks for the nice summary. I was there also so I can give one or two other details from the discussion that stuck into my head:
– Bananas produce anti-particles (through potassium I think.. not sure as I arrived very late so missed a bit of that)
– One human produces 200 anti-particles every day (not a lot!)
– ‘Does the neutrino have an antiparticle’ is a good question because the neutrino is a fundamental particle that has no charge and normally the anti-particle is the same particle but opposite charge
…if I got that right… don’t hesitate to correct me if not!
Hi Marie-Catherine, that’s exactly right – funny to think of positrons in bananas and in us!
Re neutrino, the standard answer is that it is its own antiparticle, but there is some debate about this (also I think there is such a thing as antimatter where it is not electric charge that is swapped but another quantum property)
Another very good article Cormac,
I am very excited using your article as a barometer of the discussions that are talking place around the world. The Dominium model is coming in on her 2nd birthday. When I began, no-one seemed to be mentioning the possibilities that it concludes; now it is appearing all over the place. This article even highlights some of those sparks in the “interesting questions” position in the first three questions highlighted. (As far as question 4, the Dominium model does implicate antimatter’s role in the creation of the observed intergalactic dark-matter, though it is not an obvious relationship.)
I had to laugh to see that the traditionalists have flip-flopped their positions and are now hedging their bets about the spectral signature of antihydrogen (the cynic in me wonders whether the test results are complete yet not yet published, but the traditionalist won’t abandon the tired fruitless legacy assumptions.) I make this assertion because of the humorous part of the article saying,
“Paul also addressed a question I was asked a while ago – Do we expect the spectrum of anti-H to be the same as that of H? If I have understood correctly, the answer is yes…”
This is humorous because it seems like just yesterday that the argument of the month was that the traditionalists were hedging that antihydrogen’s signature would be different, thereby proving conclusively that no antifusion ever took place in an antimatter galaxy & therefore their assumption of an all-matter Universe would be iron-clad. The old explanation went back to “fundamental differences” between matter and antimatter that leads to asymmetric baryonic decay. How adamant they used to be. Huh? But now they are hedging their bets to matching the Dominium assertion that they MUST have the same spectral signature… funny, very funny
Again, anyone interested in the Dominium retrofitting of the lens through which we view cosmologic and experimental data, come to http://hypography.com/forums/alternative-theories/18910-the-dominium-model-by-hasanuddin.html
I think that the universe is completely assymetric,and antimatters does not exist.the antiparticles are derived of the proper transformations of matter and energy and viceversa,that are assymmetric due at the variations of speeds,thence the light speed appear as constant and limit,generating a assymmetric to left-right handed rotations(spins ),thence deriving the spacetime comtinuos as variable with motion,and the antiparticles are associated to the space contraction andtime dilatation( violation of symmetry PT).thence ppear antiparticles as calculated by the reversion of pt,that is given for the metrics of curvatures of spacetime that are not constasnt.then the equations of dirac and einstein to variations of sppacetime is linked to the appering of antiparticles,violation of pt),and have extradimensions of spacetime,the time is as if had two dimensions folding the space.total 6-dimensionsor 12 dimensions in strings theory.
i think that the speed of light is not constant and limit in ours inertial referential systems due to the nature of universe,but due the pt symmetry breaking to the universe connecting space and time for spacetime continuos 4-dimensional with non-euclidean structures,with two opposite rotations;left-right randed spins( with spinors,for a non-commutative geometry and algebras)…then light speed,c,does appear as invariant to determined regions of universe,due its curvatures-metrics-
Summary of the third and final day at the European Indoor Championships
the stronger violations in the charm quaeks and in the decayment of the mesons pions evidence a new pjysics,with variations non-periodic and linear of increasing of energy with the motion.think that the violations of cp do appear violations oin the continuity of spacetime ,doing appear new dimensions of spacetimes,and implicating the speed of light have several values as limit into of topological geometrical structures,appearing exotics structures in 4-dimensions