There’s an interesting worldbuilding detail in Edward E. “Doc” Smith’s Lensman series. They’ve got this technology of “inertialessness”, which is what allows them to go faster than light, but it also has domestic uses—elevators have been replaced by open drop shafts that you fall down, inertialess, very quickly and completely safely (because “inertialess collisions cannot even be felt”). (He doesn’t say how the UP shafts work, but I’m guessing artificial gravity pointing up, since they have artificial gravity in other contexts.)
I’m not going to try to explain “inertialessness”. He’s fairly specific about how it behaves, and of course it’s not how the real universe behaves. But he’s pretty good about having the defined behavior remain consistent and control what can and can’t be done in various situations.
Most of the information on drop shafts is in two books, the actual first book and the second later prequel. (No, I don’t really expect that to make sense to anybody not already familiar with the series. But I don’t expect this article to be of any interest to people not already familiar with the series, either.)
I don’t think Smith ever actually calls them “drop shafts”, that’s a later term used in the field, but just “shaft” is rather too broad so I’m using the later term. Also I’m applying it to the ones going UP as well as those going DOWN.
Samms cut off; and, after a brief exchange of thought with Kinnison, went out into the hall and along it to the “DOWN” shaft. There going free, he stepped through a doorless, unguarded archway into over a thousand feet of air. Although it was long after conventional office hours the shaft was still fairly busy, but that made no difference—inertialess collisions cannot even be felt. He bulleted downward to the sixth floor, where he brought himself to an instantaneous halt.
First Lensman, chapter 4
So; we know there are separate “DOWN” and “UP” shafts. We know that there is no door or other guard across the archway to the shaft, which is over 1000 feet tall. We know that when Samms reaches his destination (the 6th floor) he brings himself to an instantaneous halt.
Clearly this shaft is not regarded as any danger to anybody; it has no door, no guards of any kind. (Presumably the safety issues are things like backup power for the Bergenholm that keeps the interior of the shaft inertialess, which are not visible in descriptions of using the shafts. Plus making sure the Bergenholm field and the gravity don’t reach outside the shaft.)
I’m a little unclear about the phrase “There going free”. That seems to suggests that it’s something Samms does, rather than something that happens to anybody who steps through that archway. It could be that everybody wears portable neutralizers (as Lensmen do in their armor, as described multiple places in Galactic Patrol), but it seems to me unwise to count on people not walking into the shaft without their neutralizer, plus there could be issues with people panicking and failing to turn theirs on. Also, this scene can’t be that long after Civilization first gets the Bergenholm working at all; it’s still a new technology in this scene (no precise time since the Nevian incident is given, but as I read the text a few years seems like a reasonable estimate).
It seems like the failure possibilities would be far fewer if inertia is neutralized within the shaft by mechanisms in the building, rather than by something each user has to carry and control. The phrase bothering me isn’t utterly incompatible with that, I don’t think.
Now, how fast would people be moving in these shafts? The DOWN shaft could simply work by gravity; in the free state, any object instantaneously acquires the speed that balances the forces on it against the resistance it encounters (air resistance in the shaft in this case).
The next paragraph of the book has another useful tidbit. It says “skirts went out, as office dress, when up-and-down open-shaft velocities of a hundred or so miles per hour replaced elevators”. That gives us a rough minimum speed of 100 miles per hour, and tells us the up and down shafts run at about the same speeds. (There’s a nasty question here. Is the air in the shaft free? If so, does it not resist the falling bodies at all? If that is the case at what velocity do the bodies then fall? But clearly, the air molecules push dresses around, so they’re not free, for whatever reason, so the velocity is limited. But in that case, hair as well as skirts should be subjected to 100 mile per hour winds, so styles there might also change.)
That’s in the ballpark for the terminal velocity of a human falling through atmosphere, which ought to be the speed that a free human in a 1 gee field in normal atmosphere would instantly achieve.
Now, I’m not clear how reliably I could spot the 6th floor coming a few feet from my face when I was moving at 100 miles per hour, or how reliably I could grab something to brake myself at just the right moment. But if there are many vertical rails around the edges of the shaft, say, one could grab one early and slow without stopping by gripping it lightly.
The UP shaft can’t of course work by gravity. I would argue that it would be highly advantageous for it to have the same upward force on users that the DOWN shaft has downward force, since otherwise you’d have to develop different sets of habits for the up and down shafts, which seems undesirable. (Not a safety issue though; if the space inside the shaft is all free, there’s nothing any user can do to cause accidental injury in the shaft. It might be embarrassing to miss your floor and end up at the bottom, but it won’t injure you or anyone else). So, since we know they have artificial gravity, let’s presume that the UP shaft has a 1 gee upward force, or at least that it matches the downward force in the DOWN shaft.
There’s some more information in Galactic Patrol. There’s a detailed description of the graduating class of Lensmen marching into the shaft and hitting bottom precisely on a beat of the march and continuing to march out of the shaft.
In perfect alignment and cadence the little column marched down the hall. In their path yawned the shaft—a vertical pit some twenty feet square extending from main floor to roof of the Hall, more than a thousand sheer feet of unobstructed air, cleared now of all traffic by flaring red lights. Five left heels clicked sharply, simultaneously upon the lip of the stupendous abyss. Five right legs swept out into emptiness. Five right hands snapped to belts and five bodies, rigidly erect, arrowed downward at such an appalling velocity that to unpractised vision they simply vanished.
Six-tenths of a second later, precisely upon a beat of the stirring march, those ten heels struck the main floor of Wentworth Hall, but not with a click. Dropping with a velocity of almost two thousand feet per second though they were at the instant of impact, yet those five husky bodies came from full speed to an instantaneous, shockless, effortless halt at contact, for the drop had been made under complete neutralization of inertia—“free,” in space parlance. Inertia restored, the march was resumed—or rather continued—in perfect time with the band.
Galactic Patrol, chapter 1
(2000 feet per second is 1364 miles per hour.)
This, of course, is not ordinary civilian use of the drop shaft. Note that for this ceremony it was cleared of all other traffic.
The detail of the cadets’ right hands snapping to their belts is interesting. Is that supposed to indicate they are manipulating some control that relates to the shaft? Of course, since this is not the ordinary use of that shaft, they may be doing something special that isn’t part of normal use.
We don’t know how long after First Lensman this book is set, but probably hundreds of years, so the “normal” configuration of drop shafts may well be different now than it was back then.
Either the artificial gravity in the shaft is set to a much higher setting than 1 gee for this ceremony, or perhaps the cadets are using thrusters or something to force themselves down, triggering them with their right hands at their belts. Maybe they are using thrusters to force themselves down because the DOWN shaft doesn’t have artificial gravity, only the UP shaft?
At least they don’t have to see their floor coming and stop themselves, since they’re going to the bottom. Even Lensmen might have trouble reacting fast enough to something going over 1000 miles per hour just a few feet from their face!
As usual, when one keeps poking at world-building, little issues turn up here and there.