One of my pet peeves about physics as perceived by the public and presented in the media is the way that everyone assumes that all physicists are theoretical particle physicists. Matt Springer points out another example of this, in this New Scientist article about the opening panel at the Quantum to Cosmos Festival. The panel asks the question "What keeps you up at night?" and as Matt explains in detail most of the answers are pretty far removed from the concerns of the majority of physicists.
But it's a good question even for low-energy experimentalists like myself, as it highlights the differences between the popular conception of physics and physics as it is practiced in the real world. So, what physics-related things keep me up at night? (Obviously, the answer to the general question "What keeps me up at night?" is, in no particular order, SteelyKid, sporting events, paper grading, and trashy genre fiction.)
Here's a partial list of physics-related things that have kept me up late:
Taking Data: One of the common experiences shared by most experimental physicists is that of taking data in the wee hours of the morning. This happens for a lot of reasons-- some experiments are so sensitive that they can only get useful data late at night when there aren't people around causing vibrations, and temperature variations, and turning electrical equipment on and off. Other experiments take a lot of effort to get running, so once they're going, you run them for as long as you can stand it, lest something break when you shut everything down for the night. Still others just require very long integration times-- you need to collect data for many hours in order to get anything useful. And then, of course, there's the pressure to get results first, and beat your competitors into print.
I've done my share of late-night data acquisition, mostly for a combination of the second and third reasons above. In grad school, the main experiment I worked on took data on 45-minute cycles, which needed to be paired up, so the time for a single useful data set was an hour and a half. That involved a lot of late nights at NIST.
As a post-doc, we ran around the clock quite a bit, in large part because the apparatus was very finnicky, and had a tendency to flake out for days at a time. When we got things working, we would just keep taking data as long as possible, usually until part of the apparatus exploded.
Writing Things: I'm a champion procrastinator, and given the opportunity to distract myself, I tend to take it. I've even been known to go to some lengths to create opportunities for procrastination. As a result, most of the things that I've written as a physicist have been written very late at night. When I was writing my thesis, I tended to come in at around 11am, go to lunch with the rest of the laser cooling group, spend the afternoon puttering around and distracting other people, and the finally settle in and write starting at 8-9 pm, after everybody else had gone home, and I had exhausted all my entertainment options on the proto-Web.
I've gotten a little better about this since then-- most of the book was written during daylight hours-- but I still find it hard to work when I have easy distractions. This leads to papers and grant proposals being written well after business hours.
Brainstorming Solutions to Problems: Having spent a bunch of time working on slightly flaky experiments (there really isn't any other kind), I've lost a fair amount of sleep while racking my brain to try to think of new things I could do to fix problems. At Yale, I used to routinely think of potential solutions to lab problems while walking home at night, and then spend hours turning those potential solutions over in my mind before going to sleep.
Planning Experiments: The one time I vividly recall being kept up at night by a physics problem, I was trying to do calculations in my head to determine whether I ought to completely and radically revise a grant proposal to do a different sort of experiment than what I had planned. This was a week or so before the deadline, and it had occurred to me that I could use my proposed apparatus to do a slightly different sort of experiment than that described in the many pages worth of proposal that I had already written.
I spent a couple of hours lying in bed, trying to do calculations in my head to determine whether I could reach the temperatures and sensitivities required to make the measurements needed. This didn't actually get anywhere-- I ended up having to call a couple of other people on the phone, before deciding that it wasn't a sure enough thing to justify the hasty re-writing-- but it definitely did keep me up at night.
So there's a list of physics-related things that have literally kept me up at night. You'll notice that none of them involve particle physics, quantum gravity, or multiple universes-- while the Big Questions are interesting, they're generally too abstract to keep me engaged at the level necessary to keep me up late. If you suggest a way to answer one of those questions with a low-energy AMO physics experiment, I'll happily lose sleep trying to make it work, but absent some tangible connection to empirical reality, I'm just not interested enough to stay up past my bedtime.
And that's why I'm a low-energy experimental physicist, not a particle theorist.
We work in the same way... If there is a problem that I can't get, staring at it on paper doesn't usually help. It is usually the 20 minute walk to the bus, in the middle of the night, or the next morning after staring at a problem that I finally figure out what I'm supposed to do. It's sort of incredible that very, very complex problems can sometimes be broken down in your head easier than they can on paper.
And I also seem to start work in the evening and bother people most of the day...but I am keeping up with work somehow...
"One of my pet peeves about physics as perceived by the public and presented in the media is the way that everyone assumes that all physicists are theoretical particle physicists"
Although I agree with you in general, it is The Perimeter Institute for *Theoretical* Physics, so don't they have a right to showcase the type of physics that they actually do at their own festival?
Also, I think it is slightly inaccurate to say that your beef is with theoretical particle physics specifically because it seems like cosmologists and general relativity researchers would also fall into the bandwagon that you are describing and these people generally only pull at most an equation or two from QFT. Generally, I think you just mean physicists who study events that happen at scales that are an insanely large number of orders of magnitude away from experiments we can do in the lab. Just because the public thinks that all these people are particle physicists doesn't mean that you should repeat the same mistake.
Finally, I don't think it is fair to say that the panel was dominated by theoretical particle physicists. Out of eight panelists you had Zeilinger and White, both of whom are *experimentalists* in quantum information/foundations. It is a shame that White's question was ignored by New Scientist, since it was about climate change and that is something that definitely should be keeping us all up at night much more so than any of the other questions. You also had Kadnoff, who is a condensed matter theorist and was very vocal about not all physics being particle physics. Therefore, the ratio was at least 3 to 5. However, if, like me, you don't count cosmologists as particle physicists then there were 3 people on the panel who are primarily cosmologists so the ratio is 6 to 2.
Finally, I don't think it is fair to say that the panel was dominated by theoretical particle physicists. Out of eight panelists you had Zeilinger and White, both of whom are *experimentalists* in quantum information/foundations. It is a shame that White's question was ignored by New Scientist, since it was about climate change and that is something that definitely should be keeping us all up at night much more so than any of the other questions.
My complaint was less with the panel-- which was very good-- than the article about the panel. A good deal of the actual discussion covered practical matters, but the write-up of the panel shifted the emphasis to be almost entirely on more theoretical matters, hence Matt's complaint about the list.
Of course, my real goal was not just to bitch about theory, but to use the theory bitching as an excuse for posting experimentalist stories (because, evidently, nobody wants to read that stuff on its own...). I should've been more clear about that, but I was writing this in a hurry between classes.