I just finished re-reading Ringworld and am now reading for the first time The Ringworld Engineers. What’s bugging me is Niven uses the word “dawn” a number of times in this sequel. Since daylight is provided by the system’s sun (of course) and would otherwise be constantly shining (again, of course) on the entire Ringworld, night is artificially created by the use of a ring of “shadow squares” that travel at an unspecified speed (IIRC) and are between Ringworld and its sun, so there’s no real dawn or dusk, just full on night and full on day. I may have missed it; I don’t recall Niven stating the human, Puppeter, or Kzinti time equivalent of how long it took for a shadow square’s shadow to pass over a stationary point on the inner surface of the Ringworld, nor if the gaps in the shadow square ring are the same size as the shadow squares. Niven gives the following time measures in an appendix to The Ringworld Engineers:
30 hours = 1 Ringworld day
1 turn = 7.5 days = A Ringworld rotation
75 days = 10 turns = 1 falan
It occurs to me that some information is missing here, given that the Ringworld civilization has collapsed and incredibly few (if any) of the inhabitants realize they are on a construct, or even that the construct is, in fact, a ring all the way around the star.
So, here are my questions:
What would a Ringworlder consider to be an hour; how would they divide the day and the night into smaller units? They would need some way of determining the passage of time other than the shadow squares going overhead to have any smaller measures of time than “day” and “night”. I’m assuming the “30 hours” measure Nivens gives is really an Earth hour, but that doesn’t give that much information as to what a Ringworlder would think of as an hour, minute, or second.
How would they determine the completion of one Ringworld rotation, given they have forgotten so much about their world’s condition/reality?
Would anny stars be visible during the artificially created night?
How close to Ringworld’s star would another star have to bbe and how bright would it have to be for a Ringworlder to see the star during the day?
I’ll consider “one Ringworld day” to equal “an evening and a morning”, i.e. from the beginning of the passage of one shadow square to the beginning of the passage of the next shadow square.
Those are the only questions I can think of at the moment. I’ll add more if I think of them. I will also appreciate any questions the TM add. And, as always, thanks in advance for any answers!
Well, for “hours”, that would be entirely arbitrary, and they’d probably come up with some system based on their needs. I mean, how did we end up with 24 hours per Earth day? Why not 25, or 30, or 12? Well, it mostly came down to one civilization liking the number 12 and using it a lot, and we just inherited that.
And Ringworld wasn’t always primitive. They probably inherited a time system from their ancestors, that has been maintained as a tradition, even if they don’t remember the actual source.
As for the rotation of the Ringworld, they’d be able to see at least some stars when the shadow squares were overhead, at least in the directions pointing along the axis of rotation. Stars closer to the plane of rotation would probably be washed out by light reflected by other parts of the Ringworld, like when we look at the Moon. There might be a near-polar star that everything else would rotate about. And since the rotation is every 7.5 days, it would be easier to see. Imagine our Zodiac constellations passing by that quickly, everyone would be able to figure out the pattern quite quickly, none of this “keep records for years” nonsense needed. They’d imagine it as everything else moving around them, as we used to, but the relative movement and its timing would be pretty obvious.
There would still be dawn and dusk as shadow squares traveled relative to portions of the Ringworld. The sun would be partially exposed as the squares moved. There would never be the effect of light passing through more atmosphere because of the angle, but for a short time there will be partial illumination as the sun appears to emerge or disappear behind a shadow square, and at all times there should be some illumination from light reflecting from other illuminated areas of the ring that appear to be an arch in the sky.
Stars are definitely visible - from the chapter “The Arch of Heaven”:
Sky and land were mostly black; but on the black land were blacker shadows, giving form if not color to the map; and the sky was sprinkled with stars, and mastered by that ego-smashing arch."
And as Horatius said - if you can see the stars, you can work out how long it takes until the stars are back to where they started, and now you’ve got a primitive clock/calendar, no technology or understanding of why the stars move required.
And from the same chapter - there’s definitely a time period when the sun is slowly eclipsed by the shadow square, and there’s a measurable period - long enough to load their flycycles and take off - where the light is diminishing before full darkness.
And just so you know - Engineers was written 10 years after the original Ringworld, and Niven happily discarded some truths & introduced others from different books he had written in the intervening time…
Aside: It occurred to me while I was reading the Ringworld books that a sufficiently intelligent individual (i.e., a Protector) on the Ringworld would probably deduce general relativity before deducing Newtonian gravity. Oh, it’d be easy enough to see that there was a force towards the Sun, based on the discrepancy from calculated centrifugal force, but there’d be no way to see how that force scales with distance. On the other hand, though, every shadow-square occlusion is a fresh opportunity to observe the deflection of starlight.