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Richelieu
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Gatineau
Dec 2001 time: 00:18
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quote: Originally posted by KrazyHorse
Fall upwards. |
Why upwards ? If it's liberated of gravity, won't it just start to decelerate ? Lose momentum ?
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Richelieu
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Gatineau
Dec 2001 time: 00:18
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quote: Originally posted by Immortal Wombat
Depends how strong the antigravity was. And in which direction it operated |
OK. It is full anti-gravity. And it doesn't operate in any direction. It is a applied to an object, like a force field. the object is no longer submitted to the force of gravity.
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MichaeltheGreat
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Apolyton Grand Executioner
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mooning the house that Ruth built.
Oct 1999 time: 21:18
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quote: Originally posted by reds4ever
here's a serious one then Prov, Krazy,
in a classical newtonian telescope, can you see the secondary mirror, when you look through the eyepiece? if not, why not? the light passes it? |
Yes, you do see it, in a sense. If you had significant light leakage off the primary mirror, you'd have much more distortion, but the whole secondary mirror prism and spider affect the optical performance of any compound light path 'scope. The mirror / prism / spider is out of any focal path, and because it's almost unlit, unreflective and black, it has a minimal and unfocused reflection back to the eye. The effect is not one of seeing it directly since here's not enough focused light reflected for your eye to resolve it. What you get is a certain level of optical distortion in the overall image. Most of that is due to diffraction, but a part is due to stray light reflection from the secondary structure as a whole.
That's why you have low-reflective black coatings in the inside, and baffled tube inner surfaces on larger aparture Newtownian and Dobsonian (same light path, different axis and base design) scopes. Truss-rod Newtonians accept the light leakage, but can compensate by letting you use larger primary mirrors, so you get higher absolute distortion, but lower relative distortion.
Inch for inch of aperture, refractors beat the hell out of any compound scope except for Maksutov-Cassegrain designs, which are pretty expensive. Maksutovs use an image correcting front plate like Schmidt-Cassegrains, and a primary hemispherical (almost, but much closer than the parabolic mirrors of Newtownians and Schmidts) mirror to create a different overall light path with less internal interference.
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Tingkai
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To find the Northwest Passage
Aug 2001 time: 13:18
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quote: Originally posted by KrazyHorse
quote: Why is it that the US Postal Service delivers the "mail" but the Royal Mail delivers the "post"? |
Why is it that Canada Post can't be arsed to do either? |
Because Canada Post thinks that mail is something they're supposed to post up.
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