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    princ3's Avatar
    princ3 Posts: 26, Reputation: 1
    New Member

    May 16, 2015, 12:01 PM
    Can we see aliens with future telescopes directly?
    Is there any fundamental limitation for instance like altering of space time curvature due to immense mass presence in it as general relativity predicts that forbid us to create big giant telescope with diameter of thousand of times bigger then sun so strong , enough to spy aliens daytime activity on distant planets thousand of light years far away from us ? As we exclude the limitations of atmosphere of their and our planets and obstacles on path .

    Do the any constantly changing alterations of all space time curvature between our planet and observed one due to any moving mass inside it will disturb the original image that we are going to obtain from planet that we are spying on.
    tickle's Avatar
    tickle Posts: 23,801, Reputation: 2674

    May 16, 2015, 01:18 PM
    You are asking a question that have limitations. We are no where near where you want this to be, at present, no, we cannot do this with telescopes we have, future or not.
    joypulv's Avatar
    joypulv Posts: 21,593, Reputation: 2941
    current pert

    May 16, 2015, 03:56 PM
    LOL! Where do you plan to get the materials to build a telescope thousands of times wider than the sun, and how will that alter space time (wider doesn't mean more mass) and what good will that do?
    If you are going to ask far fetched questions, have SOMETHING to back them up or you are just writing really bad science fiction.

    Much easier to send cameras into space as we are doing now anyway.
    Fr_Chuck's Avatar
    Fr_Chuck Posts: 81,304, Reputation: 7691

    May 16, 2015, 06:34 PM
    100 years ago, an airplane, was not even a valid dream. What could be possible in 100 years from now. Maybe no such thing as telescopes, they are thing of history. Maybe we read electrons in beams of light, to see universes they pass though.
    ebaines's Avatar
    ebaines Posts: 12,130, Reputation: 1307

    May 17, 2015, 06:16 AM
    Let's do a back-of-the-envelop calculation: There are three fundamental limitations on the resolution for a telescope - one is the angular resolution (how much it can magnify the image of an object), one is maintaining the mirror's parabolic shape tp withing 1/4 wavelength so the image is sharp, and the third is pointing accuracy (how steady it can be in maintaining its pointing direction). Optical resolution is determined by

    where is the wavelength of light being used and D is the aperture size of the telescope. To resolve an object 1 meter high at a distance of 3 light-years (1 x 10^16 meters, which is the distance to the closest star neighboring the sun) requires a resolution of 10^-16 radians. In visible light (m) this requires a telescope with a diameter of about 1.22 x 10^9 meters, or about 750,000 miles. That diameter is about 50% larger than the diameter of the moon's orbit about the earth. Will this someday be possible? Perhaps. But you have to build a structure that maintains its shape tp with 1/4 wavelength accuracy across its entire surface. We have a hard enough time doing this with telescopes that are "only" 10 meters across - making something with surface area 10^16 times larger would seem to be an impossible task, especially given the tidal forces that would act across it from the sun and Earth. And pointing it with an accuracy of 10^-16 radians - while moving in orbit and being affected by the gravitational pulls of the sun and planets - would also be impossibly difficult in my opinion. So I have to say no - using a telescope to see details on planets orbiting other stars is not practical at all.
    ebaines's Avatar
    ebaines Posts: 12,130, Reputation: 1307

    May 18, 2015, 06:00 AM
    Thinking about this some more.... I would add that for good magnification you want a telescope with a large focal length, meaning the ratio of the distance between mirror and focal point to the diameter of the mirror should be at least 3, and better yet more like 6. So the length of this telescope beomes about 6 million miles - and again requiring that distance to be maintained to a high degree of accuracy.

    And one other point - given that the surface area of this telescope's mirror is about 10,000 times greater than the cross-secrtion area of Earth, and given that Earth gets hits by hundreds of meteors per day, you would need some mechanism to protect the mirror from asteroids large and small - perhaps something like the shields used on "Star Trek" and other sci-fi movies.
    princ3's Avatar
    princ3 Posts: 26, Reputation: 1
    New Member

    May 18, 2015, 07:44 AM
    My concerns were about the curvature of spacetime more pricisely what about all the moving massive stuff between us and observed objects making alternations of spacetime curvature and deflecting the light from the images in many different directions making the observations impossible ?
    ebaines's Avatar
    ebaines Posts: 12,130, Reputation: 1307

    May 18, 2015, 08:35 AM
    In the scenario I described above we were talking about a telescope that could discern 1-meter objects at a distance of "only" 3 light-years. I don't think there are any massive objects between here and there that would cause serious warping of the light rays. And even if there were - I would think any bending of light caused by gravitational effects would have the same impact on all the photons coming from the object being observed in the same way, not randomly.
    princ3's Avatar
    princ3 Posts: 26, Reputation: 1
    New Member

    May 18, 2015, 10:35 AM
    What about 100 light years across ?

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