Geek Flame

[selenite0]

I'm not very active on the Pyramid boards--I don't check them often enough to participate in the give and take. But when someone was being pedantically wrong about the orbital mechanics of a space elevator I had to post a correction. And then I could not resist letting him have it for this assertion:

> And there is no such thing as centrifugal
> force, it's a illusion based on inertia.

Bah. Centrifugal force is real. Inertial reference frames are an illusion. Nobody in human history has ever been in a non-rotating reference frame. They're a purely theoretical construct. Save it for the physicists. Anybody doing practical work uses centrifugal force when it's the most sensible way to describe the system.

Comments

[thegameiam.livejournal.com]

I'm with you: I've had some arguments recently with people who argue about theoretical packet networks but don't have experience in real ones - I don't care if MPLS is faster to switch than IP on a theoretical basis: in a real network, IP is faster. (mind you, only a little bit faster, but still, the issue is that MPLS is not faster).

two planets

[p-o-u-n-c-e-r.livejournal.com]

I think it was Jerry Pournelle who introduced me to the following thought experiment, which is almost certainly not original with him:

Suppose the entire system consists of two planets -- the entire rest of the universe may be modeled if necessary by a homegenious spherical wall of mass a lightyear or so off. So inside the universal sphere an observer on either planet notices that the other plaent appears to be oriented with a pole directed at the observer, around which the observed planets rotates.

Okay, so observer 1 on planet 1 sees planet 2 spinning around a "north pole" co-located with observer 2. But observer 2 sees planet 1 spinning around a pole co-located with observer 1.

Which planet, if either, exhibits Coriolis (centrifugal) forces at the equator?

Re: two planets

[selenite.livejournal.com]

I may need a diagram to grasp what you're getting at here. Offhand it seems that the relative orientation of the planets is irrelevant. If a planet is spinning it'll generate centrifugal (separate from coriolis (http://en.wikipedia.org/wiki/Coriolis_force), which is different) force on anything attached it in a direction perpendicular to the spin axis. If it's anything like our planet that will be unnoticable compared to the gravitational force it exerts. So in answer to the question, both will.