Another ask the experts sort of link. Corresponds with the others pretty well.
It would be pretty weird, standing on a flat plain (near the circular poles) and feeling like you’re being pulled down a hill. Maybe your senses would tell you you were merely on a vast hillside, with “real” hills feeling like terraces.
Seems like a darned impractical sort of world to live on. Everything wants to pool in the inner ring of the torus. Only at the outer equator would things feel “normal” to our experience, and yet that position is likely unstable for anything not firmly rooted down or willing itself to stay there. Everywhere on the inner equator would probably be underwater, if the planet had as much ocean as the Earth does. Living on the shores of this inner-equatorial ocean would give one the bizarre experience of being constantly pulled as if downhill from the shore into the water. How would the water pile up in the middle? Depth would be greatest right at the equator, I guess.
It’s really tough to imagine an Earth like environment suddenly transported to Donutworld. Seems like things would go completely wild, with calamatous redistribution of materials according to their viscocity, etc.
Why would your senses tell you anything other than that you were standing on a hillside? For a sufficiently large torus you wouldn’t be able to discern any curvature, so you would only have gravity to go by.
You could make a more practical (can I use that word when the torus has to be supported by an unobtanium-scrith alloy?) torus by choosing a noncircular cross-section so that the surface is an equipotential (this may require a torus of nonconstant density, I’m not sure). This would avoid the everything-runs-downhill problem and allow outer oceans. On the other hand, a vast low-gravity inner ocean sounds pretty cool too.
Oh, never mind, I think I see what you mean here: the perception of gravity dueling with the human expectation of a horizontal horizon line. OK, I can see that being a little disorienting.
Yeah, that’s basically what I mean. Imagine yourself on a hillside: You look down, and there’s level ground somewhere below. You might even see a summit above you. That’s simply the way our experience tells us topography is arranged, and we can always point to the center of the Earth. It’s down. The hillside is at an angle, the plain roughly perpendicular (given that the curvature of the Earth is difficult to perceive until high altitudes are reached, so a plain looks flat).
So, now you’re transported to a place where even a pan-flat plain that stretches off to the horizon in all directions feels exactly like being on a steep hillside. Or maybe there’s a hill not far off, and the slope facing away from the inner equator is, to your senses, a terrace on an incredibly vast slope. A landscape photograph level to the horizon would look perfectly normal. A film of the same scene would look bizarre, with people leaning forward (if they’re moving away from the inner equator), as if in a steady gale, as they traverse the aforementioned pan-flat plain.
I figure actually being in that scene would be weirder still.
This is on the right track. A torus with the correct non-uniform density could have a “level” surface. That is, at least one gravitational equipotential surface could have toroidal symmetry. Rather computationally difficult to determine the necessary density distribution, though.
The film would only look strange if you set the camera up in a strange way. If you put it on a normal tripod or had someone carry it normally, it’d just look like people on a hill.
This brings up another observation: Think how easy navigation would be on such a planet! You could look up to see whether you were on the inside or the outside of the torus. If you were on the inside, you could probably determine your location using just a plumb bob and a sight. And you could use a level to determine compass directions.
You could make a more practical torus planet more practically by simply making it spin such that the gravity from non-local areas of the torus are cancelled out by centrifugal force. Not only would you get rid of the massive hill effect, but the planet wouldn’t be trying to collapse in on itself either.
True; though then you’d have tidal forces trying to rip it apart instead. And the days might be shorter than you’d like. (Fun times with low gravity and Coriolis forces in the middle, though!)
Wouldn’t the Coriolis effect be more pronounced at the poles where the distance from the center of rotation increases most rapidly?
From either equator when you go 100 miles toward the pole you’ve hardly increased your distance from the center at all and the linear speed of rotation of the surface around the center is nearly the same as at the equator. On the other hand, at the pole when you go 100 miles you have increased or decreased you distance from the center by virtually 100 miles and so have changed the linear speed of the surface accordingly.