Today I visited Utah’s TRIGA: a nuclear reactor located in the building where I’ve had an office for about nine years. I’ve had a low-grade fascination with these devices since reading about them many years ago in one of Freeman Dyson’s books. Unlike powerplant reactors, which rely on elaborate safety systems, the TRIGA series is fueled by uranium zirconium hydride, “which has a large, prompt negative thermal coefficient of reactivity,” according to Wikipedia. So, as it heats up, the reaction is damped, making any sort of meltdown highly unlikely. This kind of built-in safety is quite elegant, and — as a specialist in embedded software — makes me far more comfortable than would an engineered system.
Ben, a PhD student in nuclear engineering, showed me around and answered lots of questions. I even got to borrow a dosimeter and look down into the core. The coolest part — and this is something I’ve wanted to see for a long time — was the blue glow of Cherenkov radiation: light caused by neutrons escaping the core faster than the speed of light in water. It was also interesting to see ripples on the surface of the water, caused by convection as the reactor dumped heat into the pool. Although almost no radiation escapes the pool, it was still nice to see a 0.0 reading on the dosimeter on exit (not sure what the units were, perhaps millirems).
Last month I attended a program committee meeting in Paris. It was a great trip: convenient since Delta has a direct SLC-CDG flight, productive since the meeting was useful and I think the program ended up being strong, and also fun since I took two extra days to putz around Paris, a city where I haven’t spent any significant time since 2000. But, it got me thinking: is this really the best use of resources?
A bit of background: it is common for conference paper committees in computer science to meet in person to decide which papers are accepted and which are not. This is one of the most important jobs that academics do, so of course we want to do a good job. As the thinking goes, there are in-person effects that cannot be captured in a telecon or over email, so we must meet in person in order to make the right decisions. Although I’ve run two such meetings and attended many more, I’m not totally sure they’re necessary. Why not? First, there are always a lot of papers that everyone agrees (ahead of time) should not appear in the program. Also, there are always some papers that everyone agrees should be in the program. Thus, the meeting is only about the marginal papers, and there are reasonable arguments that the decision process for marginal papers is quite noisy.
Let us look at the economics a little more closely. If we put a meeting in Chicago and have 20 attendees from the USA at 1000 miles of one-way air travel each, that’s 40,000 miles. If there are 5 people from Europe at the meeting (at 4000 one-way miles each), that’s 40,000 more miles. Add 3 from Australia or Asia (at 7000 one-way miles each) and we get 40,000 more miles, for a total of 120,000 air miles. At 50 passenger-miles per gallon, this PC meeting is burning 2400 gallons of jet fuel, or more than a quarter of a standard 9000 gallon tanker truckload. That seems like a lot.
The next question to ask is: how high do oil prices have to rise before in-person PC meetings are dropped? That is, before the community decides that the cost of 2400 gallons of gas exceeds the incremental benefit of the in-person PC meetings vs. remote? I don’t pretend to be an expert on the psychology of academic meetings or the economics of air travel, but my guess is that a phase change occurs at a price not hugely greater than the 2008 peak, maybe at $250/barrel.