| Story Views | |
| Now: | |
| Last Hour: | |
| Last 24 Hours: | |
| Total: | |
Blog Table Discussion with Puff the Mutant Dragon (Part I) [Uncertain Principles]
My post post Faster Than a Speeding Photon, doing a Q&A explainer of the OPERA fast-neutrino measurement was picked for inclusion in The Best Science Writing Online 2012 (confusingly published in late 2012, featuring blog posts from 2011…). As promotion for the book, it was suggested that pairs of authors from the collection “interview” each other about their posts, blogging, and whatever else, and I was paired with Puff the Mutant Dragon.
We exchanged several emails over a week or so, and thought about cutting them up into typical Q&A type “interview” posts. That seemed like it might be kind of time-consuming, though, so I suggested instead that we steal an idea from Slate, and copy their “Breakfast Table” format of alternating little articles in the form of emails, which would require much less editing to make comprehensible. Since this was my brilliant idea, I get to start, then Puff will post a response, then I’ll post my response to that, and so on. I’ll try to edit each post to add a link to the next in the chain when it goes live.
Puff:
Congratulations on getting picked for the Anthology Series Formerly Known as the Open Laboratory this year. You mentioned off-line that you were a little surprised that they picked your Sunrise in the Garden of Dreams post. I hear you on that– this is the third or fourth time I’ve gotten a post into one of the Open Lab anthologies, and I don’t think any of them have been what I would consider my best posts of the year. This year was probably the best of the lot, since it’s actually a physics explainer post. Most of the others have been more meta articles about the structure of academic science or what have you. It’s very strange.
The FTL neutrino incident that’s the subject of the post in this year’s anthology turned out to be a false signal caused by a “loose cable,” which was actually a fiber-optic connector that at some point was unscrewed and then reconnected wrong. My guess is that whoever put it back together managed to cross-thread it a little bit, so it felt like it was on tight, but on close inspection wasn’t screwed down all the way. That shouldn’t cause much of a problem– unlike a loose copper wire where you can change the characteristics of the electrical circuit dramatically with a poor connection, a loose fiber optic should only delay the signal by the time light takes to cross the space between the connector where it is and where it should be. In order to get a 60ns delay, like they were seeing, you would need a gap of about 60 feet, so as long as the cable wasn’t across the room from where it was supposed to be, you wouldn’t expect it to create a timing issue.
Unfortunately for the OPERA collaboration, they also had some weird stuff going on with their detectors. The pulses they were using were extremely long, and the detector that converted the light pulses from the fiber optic to electrical pulses they could analyze had a slow and non-linear response. That combination, which is not at all something I would’ve expected from a timing system claiming nanosecond accuracy, created a situation where the loose fiber optic produced a huge delay. I blogged about it later, though the announcement of the “loose cable” explanation came out about two days after I approved the proofs for the book…
The whole thing was really embarrassing for the collaboration, and the people in charge resigned in disgrace. I think it’s slightly less stupid than a lot of descriptions make it sound– the combination of effects that produced the timing error is kind of unusual, and it’s entirely possible to mis-thread those fiber connectors in a way that would get past a quick inspection (that is, somebody casting a quick eye over it, and even testing the connection by trying to turn it. But it wasn’t a great moment for experimental science.
Contrary to a lot of people who proclaimed the whole thing a giant disgrace, though, I think it’s an example of a case where the system worked as it’s supposed to, at least within the scientific community. They found an anomalous result, they did all the consistency checks they could think of, and then they shared their results with the physics community, asking other scientists to check their work. The publicity was less a matter of grandstanding by the experimental collaboration responsible– their preprint and public statements were pretty cautious, for people claiming a really dramatic result– and more a consequence of the new media environment. The arxiv, which would’ve been a quiet back channel for sharing preliminary results a decade ago, is now monitored very closely by journalists and bloggers, and years of hard work by the particle physics community have created an environment where anything remotely associated with CERN is automatically big news.
You also asked about how long I’ve been blogging. I’ve been doing this for a bit more than ten years. I did a big retrospective series back around the actual anniversary, then
2012-10-01 08:41:08
Source:
