On a geek tangent, it always bugged me that the mass of Babylon 5 was given as 2.5 million tons.

That's only 25 times the mass of an aircraft carrier, despite B5 being 5 miles long (i.e., 50 times the length, though probably only 10-20 times the width and height). It's 5,000 times the volume of an aircraft carrier at least. True, B5 has some large interior voids, but still nowhere near enough to make up for that.

If it is really made of "metal" in terms of the elements we're familiar with, that just doesn't seem likely unless it is metal in some sort of ultra-thin foams that neverthless have enough structural strength to support 1G loads around the rim.

Damn! I actually want to a J. Michael Strazynski talk just last month. Should have asked him during Q&A.... would have only been the second or third geekiest question of the night.