Would it be possible to observe an alien city?

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Discussion Overview

The discussion revolves around the feasibility of observing an alien city using telescopes, particularly focusing on the required mirror size and angular resolution necessary for such observations. Participants explore theoretical limits and practical challenges associated with imaging distant exoplanets and potential alien structures.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant questions the circumstances under which a telescope could observe an alien city and whether the required mirror size is prohibitively large.
  • Another suggests that evidence of alien activity might be detectable through radio transmissions rather than direct imaging.
  • A participant expresses skepticism about the possibility of imaging exoplanets, stating that current technology is insufficient for such tasks.
  • There is a reiteration of the need for an extremely large mirror, potentially larger than Earth, to achieve the necessary resolution for observing distant structures.
  • One participant queries whether a sufficiently large mirror would allow for the observation of structures on orbiting planets or if it would only provide images of the stars themselves.
  • Another participant attempts to calculate angular resolution based on hypothetical mirror sizes and distances, expressing uncertainty about their mathematical skills.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the feasibility of observing an alien city, with some expressing skepticism about current capabilities while others explore theoretical possibilities. Multiple competing views remain regarding the necessary technology and methods for such observations.

Contextual Notes

Limitations include unresolved calculations regarding angular resolution and the dependence on the definitions of observational capabilities. The discussion does not resolve the practicalities of telescope design or the implications of mirror size on imaging distant objects.

momo666
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Under what circumstances would a telescope be able to observe an alien city, supposing such a structure was present on a planet?
Are the requirements so high, say the mirror size, that this is simply wishful thinking or is this actually possible?
More specifically, suppose our imagined telescope is 15m in diameter. Is that a fundamental limit that prevents us from achieving such a feat? From what I gather, this kind of observation and detail would require an enormous diameter.
 
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I don't recall the formulas for calculating the necessary mirror size. It might be possible to find evidence of alien activity (assuming they exist) through radio transmissions.
 
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This is far, far out of the realm of possibility. We can't image exoplanets, and indeed most stars.
 
momo666 said:
Under what circumstances would a telescope be able to observe an alien city, supposing such a structure was present on a planet?
Are the requirements so high, say the mirror size, that this is simply wishful thinking or is this actually possible?
https://en.wikipedia.org/wiki/Angular_resolution
 
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So there's your answer - for all but the very nearest stars, the mirror would need to be bigger than the earth.
 
Say the mirror is bigger than the Earth or whatever huge diameter our thought experiment requires. Would that merely give us a picture of the star or would it allow us to observe structures on the orbiting planets?
If it only gives us a picture of the star, are we talking about 2 pixels added together or something like what Hubble gives us when we observe a crater on the Moon?

Edit: So this will clear it up I think.
Suppose the target is 1 light year away and our mirror diameter is 100m. What would be the angular resolution? My math is bad so I got 10m.
What if the mirror diameter is the size of the Earth?
 
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momo666 said:
Say the mirror is bigger than the Earth or whatever huge diameter our thought experiment requires. Would that merely give us a picture of the star or would it allow us to observe structures on the orbiting planets?
If it only gives us a picture of the star, are we talking about 2 pixels added together or something like what Hubble gives us when we observe a crater on the Moon?

Edit: So this will clear it up I think.
Suppose the target is 1 light year away and our mirror diameter is 100m. What would be the angular resolution? My math is bad so I got 10m.
What if the mirror diameter is the size of the Earth?
berkeman said:
Asked and answered. Thread closed for now.
 

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