# Tales From The Industry XXVIII – Angels, Demons, and Antimatter

So, apparently there is physics in the upcoming huge film Angels and Demons (and presumably the book). Lots of it. I did not know that until recently. So imagine my surprise a few months ago when I got a message from a producer (Natalie Artin of Prometheus Pictures) of a documentary about it, asking if I’d like to contribute, talking about aspects of the physics.

They wanted me to talk about anti-matter. This is as a result of finding a blog post of mine over on Correlations, entitled “Not Science Fiction”, which starts:

Anti-matter. Seeing the previous word, you immediately glance back at the title, right? Strangely, it has been 80 years since the discovery of anti-matter, and we use it routinely in our technology. Nevertheless, anti-matter is still thought of as something from science fiction (and mostly bad science fiction at that).

It all goes back to one of my favourite theoretical physicists, Paul Dirac, and you might like how he found it (roughly). He essentially did it by […]

I agreed to talk, if I could focus on one of the main issues of my post: That anti-matter is not weird stuff of science fiction, but actual routine science…. so routine that it is used commonly in medical diagnosis, for example. The “P” in PET scans stands for “positron”. The positron is the anti-electron. (The “E” does not stand for “electron”…. the thing that we use in all our electronic devices, as you might have guessed, but “emission”.) The science-fictiony sounding thing that they are evil twins that annihilate in an explosion is….. true. The trick is to introduce an agent into your body that produces positrons. They meet the electrons that are already inside you (all your atoms have them and you’re made of atoms, remember?). The “explosion” is simply a burst of high energy light (gamma rays). Actually it is two photons (particles of light), which the scanner detects and uses to reconstruct the location of the meeting point (that’s the “T” – “tomography”). Do this with a lot of positron-producing (by a kind of radioactivity called $$\beta$$-decay) fluid flowing around your body (the radiotracer) and it’ll allow an informative image of the interior of your body, showing concentrations of the fluid (which correlates well with things like cancerous growths and so forth).

So I agreed to talk on anti-matter, on condition that I mostly focus on that rather than the whacky speculative or outlandish stuff (since if they want that they’ll no doubt get someone like Michio Kaku to do that anyway). (I don’t mind doing some of that type of thing too – carefully – but this time I wanted to make sure that someone brought out the everyday aspects of anti-matter, for it is an often-overlooked aspect.) I would also talk a bit about some of the things going on in particle physics currently.

I offered something more. Rather than have me sit in my office talking about this in the abstract, why not come to an actual hospital and see and film an actual PET? That would be a really nice complement to the other stuff they’d have on film concerning the rest of the movie (they went to CERN to the LHC, the particle accelerator – apparently it has a role – and to the Vatican, and interviewed people like Tom Hanks (this is as close as I’ll come to appearing in a movie with Tom Hanks… huh…), and hopefully (depending how they use the material) ground aspects of the film in reality nicely.

They liked this, and so I went into location-seeking mode and started reaching out to some of my friends and colleagues on all three USC campuses (the University Park one, Health Sciences, and also Children’s Hospital), and within 24 hours had some good leads. (Thanks Barbara, Justin, )(Some of my facebook friends will now understand the status update “Clifford is looking for a PET”. The various guesses: a small furry animal, a scarily submissive date, an old classic computer, etc, were not right. Promised I’d explain didn’t I?)

So it was all set up, and the shoot went rather well. I was given the option of using either the human scanner, or one of the smaller ones that they use for scanning animal subjects in research. I chose the former, attempting to avoid the obvious confusion that will arise – I’m trying to explain that PET does not stand for “pet”, but showing a machine designed to image small furry animals. Confusing!!!! (For those who have commented: To the left is evidence that I don’t always wear a blue shirt when doing this sort of thing.)

The producers (Timothy Crehan, Gary Simson) and other crew, (Jayme Roy, Hilary Stewart, and Ian Eastman) were a lot of fun to work with. Here they are:

The director of the scanning center we used, Peter Conti was very helpful, as was Carol McCann, one of the staff. In fact, I ventured another idea to the filmmakers. Form talking with him, Peter seemed to me a very clear and personable sort of guy, so why not have him talk about aspects of the machine on camera to me, rather than have me explain the machine on camera to the audience? Seemed more honest and natural to me (and give the audience a rest from seeing my mug all the time for the segment.) So that is what we did. Here he is being miked up by Hilary, in the middle of preparing for a take, and a shot of the command centre’s computers (where the images show up) (Click for larger view.):

I’ve no idea how much of this they will use – if any! – but I was informed that the film, “Angels & Demons: Decoded”, is on the History Channel on Sunday night at 8:00pm. Enjoy!

-cvj

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