A lake at the South Pole would have the shape of the geoid, the equipotential surface due to gravity and centrifugal force. Would you expect the lake to somehow have a concave surface? Think about cost and maintainability. Which is easier, a liquid mirror on Earth with an extremely elaborate servo controller, or one on an asteroid? -- Gene From: Henry Baker <hbaker1@pipeline.com> To: math-fun <math-fun@mailman.xmission.com> Sent: Thursday, March 5, 2015 9:37 AM Subject: Re: [math-fun] newton rotating liquid mirror Couldn't we build such a mirror at the South Pole using just the Earth's rotation? It would want to be pretty big, but there's lots of open space down there. Even if you didn't care about visible light wavelengths, you could still provide a bunch of liquid-filled tubes to distribute the correct height to each location where you could put a small radio antenna. Alternatively, you go through the asteroid belt to find a decent size spinning asteroid and install your mirror there. Yes, you don't have much control over where it points, but there are some types of investigations where that might not matter. At 08:56 AM 3/5/2015, Warren D Smith wrote:
Adam P.G's blog seems amazinger and amazinger. I don't understand his life census, but it too seems amazing.
I noticed some post by him about the spinning liquid parabolic mirror being invented by Isaac Newton. I actually made one of those mirrors once using a phonograph turntable and plastic resin. The mirror was quite decent, although I daresay it was not good enough for a quality telescope. A lot of people may be willing to donate an old phonograph turntable no longer useful to them for music.
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