When John Sheridan, the new commander of Babylon 5, gives his lucky speech at the end of episode 1, season 2, the bridge seems completely empty. Is this just a joke that was not thought through, or does Babylon 5 really have periods of time when there is nobody on the bridge?
This was a major issue with fans back when the episode aired. JMS, the creator of Babylon 5, was forced to address it over and over again on Usenet.
From the Lurker's Guide page for Points of Departure, this looks like the most concise post:
It has been established, in prior episodes, that there are brief periods when C&C is in "standby mode," during which time no ships are due, the station is in "night" cycle, and the operational equipment in C&C goes through routine backup and maintenance. In "Midnight on the Firing Line," our first episode, Ivanova is told by Garibaldi that Sinclair is in C&C when it's in standby mode because he likes the quiet during those brief periods (usually only about an hour or so); in "Chrysalis," Ivanova asks Tech 1 if any more ships are due in for a while, is told no, and she puts her feet up on the console, watching the news, with the place pretty much deserted.
This isn't the bridge of a starship; this is mainly a center of operations for docking and other station activities requiring command personnel. Every separate department -- environmental, other resources -- has its own separate control center, with lots of redundency.
In addition, there's always somebody monitoring stuff as it comes through, so if there were any kind of problem, there'd be somebody on site in C&C in thirty seconds. Basically, we're talking an hour or so once every 36 to 48 hours. I could've explained this in dialogue, but it would've taken the edge off the revelation and humor, and I figured we'd done this before enough times that it wouldn't be an issue.
So yes, Sheridan was giving the speech to an empty command center. The good luck speech, if I remember correctly, has to be given within 24 hours of taking command - it's just part of his tradition. Given all the activity in the episode, he was forced to delay it until the last possible moment, with only a couple minutes remaining in those 24 hours.
We don't see the whole bridge in the episode, so we don't know whether it was "completely" empty or not.
The writer of the show himself weighed in on this question already however(source):
As noted elsewhere...we have previously established that the Dome is periodically on Standby Mode, when the system is performing autmoated (automated) backups, routine maintenance, that sort of thing. It was in "Midnight," when Garibaldi informs Ivanova that that's where he likes to go, when it's on standby, and is quiet. It was in "Sky," when Ivanova asks Tech 1 if there are any more ships due in for a while, is told no, and she puts her feet up on the console, nobody else around.
Also, B5 tends to run on human cycles of day and night, something we try to reflect in the sets and effects, showing the Garden bright during day times, and dark during night stuff (as around dinner time in the Fresh Air Restaurant). Maintaining such cycles has been found to be critical in these kinds of environments.
The standby mode only happens every 36-48 hours, for about an hour. Most departments also have their own control areas, using C&C mainly when command personnel are required. In addition, there are folks monitoring C&C, and if anything should happen, someone could be there within seconds.
Which explains why it is empty (or nearly empty) when Sheridan gives his speech.