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This answer in Space Exploration SE has got me wondering how careful and meticulous Kubrick was about getting the diameter and speeds of rotation for the two major instances of artificial gravity shown in the film; the large space station in Earth orbit, and the the interplanetary ship sent to the Jupiter system.

Kubrick being Kubrick (or Clarke being Clarke) I would assume that this would have been carefully done. I would expect that Kubrick took care to ensure that the sizes and rotation rates shown would be consistent with the amounts of gravity portrayed. While we can't see the exact amount of gravity in the rotating ring of Odyssey, we do see people sitting, standing and running.

Is it in fact known that this was done?

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  • Answers and comments to 2001: A Space Odyssey book physics are helpful but doesn't address this directly.
    – uhoh
    Dec 2, 2020 at 0:07
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    This is covered nicely by (physicist) Rhett Allain in this article wired.com/2013/06/…
    – Clara Diaz Sanchez
    Dec 2, 2020 at 0:18
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    maybe better to say Clarke being Clarke - since Arthur was the true space guru
    – NKCampbell
    Dec 2, 2020 at 0:32
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    I'm not sure honestly :) - just saying the Clarke had in many ways 'written the book' on certain scientific facets of space travel more than a decade prior (in non-fiction form) "The Exploration of Space" - one may find more details on the production process in Clarke's making of book 'The Lost Worlds of 2001"
    – NKCampbell
    Dec 2, 2020 at 1:27
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    Note that the claim in the linked answer isn't that the gravity wasn't strong enough, but that at that radius (and spinning fast enough to make 1G) the rotational effects would be noticeable to humans standing up. That's not just simple physics, it's biology, and thus easy to believe Kubrick could have not known about. Perhaps spinning slower and making less gravity could be ok for biology at that radius?
    – Peter Cordes
    Dec 2, 2020 at 3:34

2 Answers 2

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Partial answer:

In the book the "carrousel" in Discovery is 35 feet in diameter.

As it made one revolution every ten seconds, this carrousel or centrifuge produced an artificial gravity equal to that of the Moon.

For the film, the book The Making of Kubrick's 2001 states that the carrousel set is 38 feet in diameter, so that's essentially the same.

However, I attempted to check the rotation rate of the carrousel in the film, and it appears to be rotating at approximately half the speed given in the book. The shot I chose does not show a full revolution; the frames shown depict a half revolution in approximately 10 seconds.

enter image description here enter image description here

If correct, film Discovery would have about half a Lunar surface gravity - I have not accounted for the slightly larger radius.

Sources:

  • 2001 A Space Odyssey, Arthur C. Clarke, 1968, first NAL printing, page 101
  • The Making of Kubrick's 2001, Jerome Agel, 1970, first Signet printing, page 67
  • screenshots from film

Should one want to check ACC's math: If I did the math right (always a big if) I get ~7 ft/s2 for those (obviously rounded-off) numbers whereas lunar gravity is ~5 ft/s2 so again, pretty close.

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    @uhoh thanks, Ah, I missed the part about the space station. I'll edit to clarify that it's a partial answer. I have no info about the space station.
    – Organic Marble
    Dec 2, 2020 at 1:29
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    there's an argument that using math can get the question insta-closed. I think your sources are sufficient.
    – uhoh
    Dec 2, 2020 at 1:37
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    "Do the math, save the world"
    – Organic Marble
    Dec 2, 2020 at 1:40
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    Your math looks good to me; Clarke's specified rotation speed would give ~0.21g, as compared to the Moon's gravity of 0.17g.
    – Clara Diaz Sanchez
    Dec 2, 2020 at 9:19
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    Of course. Just closing the loop on the question in case it’s not clear to anyone. Kubrick is my favorite director and the film is a masterpiece.
    – Todd Wilcox
    Dec 2, 2020 at 14:35
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The book 2001: The Lost Science, which is filled with diagrams and notes from Frederick I. Ordway III (the main science consultant for the movie), says on page 41 that the Discovery has an internal centrifuge which spins to create artificial gravity, without the whole ship needing to spin with it. Then it says on p. 56 that they had a choice of different possible ways it could spin, either constant low-gravity or short periods of higher gravity (not clear what this choice was based on, my first guess was something to do with energy requirements, and @uhoh also had a good speculation in a comment that they were thinking in terms of total 'g-hours' needed to maintain a healthy body). They opted for a constant low-gravity spin, but they realized the set was a bit too small for what would be needed to avoid problems with the Coriolis force that would be experienced when moving around inside the centrifuge:

We had the option of putting the Centrifuge on for, say, one to two hours a day to produce up to 1.5 g, or permanently have it rotate to provide about 0.2 to 0.3 g. We chose the latter. There was, of course, the problem of Coriolis forces, which on small diameter wheels would cause dizziness to astronauts walking along the rim. Calculations showed that a centrifuge should be at least 300 ft in diameter to reduce to acceptable levels the inconveniences caused by the Coriolis forces, but such a diameter was beyond the capabilities of the M-G-M British Studios — and our budget. So we never really mentioned the diameter of the wheel with which we had to work; in fact, there was no purpose to reveal the measurements at any time. Visual appearances were what counted.

The introduction to the book says "A significant portion of the background text presented in the following pages was written by Fred Ordway at the time of production", and the phrasing in the excerpt above ('We had the option') would suggest it's one of the parts that was written by Ordway.

So, the short answer is that in their heads the centrifuge was meant to have a diameter of about 300 feet, but they couldn't get a set that big for budget reasons, so they just used a little visual artistic license. An article here says that based on visual appearances, it looks like the centrifuge set used in the film actually has a radius of at most about 8 meters (which would be a diameter of 53 feet), and @Organic Marble mentioned in a comment that the book The Making of Kubrick's 2001 by Jerome Agel said that the set was actually about 38 feet in diameter.

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    I had to read this several times to derive what I think the answer is - I could be a dope though. Any chance of drawing out the main conclusion to be a little clearer as to how it answers the question? (my interpretation, fwiw is "looks over science. Yeah...what was shown on screen was likely far too small to be technically accurate but it looked good and was on budget"
    – NKCampbell
    Dec 2, 2020 at 21:35
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    @NKCampbell - That's right, I added a little summary at the end.
    – Hypnosifl
    Dec 2, 2020 at 22:10
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    Making of Kubrick's 2001 says the carrousel set was 38 ft in diameter.
    – Organic Marble
    Dec 2, 2020 at 23:29
  • @OrganicMarble - Thanks! There seem to be two books with that title, one by Piers Bizony and another edited by Jerome Agel, which one does that number come from? Do you have the page number?
    – Hypnosifl
    Dec 2, 2020 at 23:58
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    @Acccumulation a guess here; to me it sounds like this is an estimate of what might have been thought necessary for humans; 2 hours at 1.5 g and 12 hours at 0.25 g are both "3 g-hours" and maybe someone estimated that that might be a good biological replacement for living on Earth. The problem is that at this time there was probably very little knowledge or even theory about that, so I wouldn't give too much weight to my guess. It's a pretty interesting story how bone mass loss in microgravity was first discovered, and if you don't know it and ask maybe (at)OrganicMarble will link you to it!
    – uhoh
    Dec 4, 2020 at 12:32

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