4 ms·
Hmm. Good idea. Or put it in orbit. Let gravity deform the bubble. Maybe.
by swayvil 4y ago
Hmm. Good idea.
Or put it in orbit. Let gravity deform the bubble. Maybe.
- klyrs 4y agoAfter making that suggestion, I realize that Earth's gravity would make perfectly parabolic lenses if the suggestion was viable. That people aren't already getting perfect(-enough) parabolic lenses from this technique suggests to me that it's probably not actually viable. Oh well. Come to think of it, a film suspended from a ring would create a catenary[1] under constant gravity -- which is pretty darned close to a parabola but, I suspect, not good enough for astronomy. [1] https://en.wikipedia.org/wiki/Catenary https://en.wikipedia.org/wiki/Catenary
- eesmith 4y agoI think the link you want is https://en.wikipedia.org/wiki/Liquid-mirror_telescope https://en.wikipedia.org/wiki/Liquid-mirror_telescope - "The liquid and its container are rotated at a constant speed around a vertical axis, which causes the surface of the liquid to assume a paraboloidal shape. This parabolic reflector can serve as the primary mirror of a reflecting telescope." This method in this article uses the same principle: “It has long been known that rotating liquids that are aligned with the local gravitational axis will naturally form a paraboloid surface shape,...“ See also https://en.wikipedia.org/wiki/Liquid-mirror_space_telescope https://en.wikipedia.org/wiki/Liquid-mirror_space_telescope .
- klyrs 4y agoI'm familiar with liquid mirror telescopes, but I was responding to some theorizing about using an inflated film. Without gravity, the film would produce a sphere; suspended in gravity, it would produce a catenary.