4 ms·

#1 is a lot crazier, and more like: "we can only look at specific places, our detectors can only detect things which degrade as distance increases, and we might

#1 is a lot crazier, and more like: "we can only look at specific places, our detectors can only detect things which degrade as distance increases, and we might not be listening at the right frequency. So even if there were a civilization in this tiny, tiny region of the universe we are looking at, if they are too far away/obscured by debris/gas clouds, using wavelengths we aren't actively monitoring, we don't see them.

ntsplnkv2 8y ago
Okay that explains why we can't see them. Why can't they see us? All the arguments for life say "the universe is so big there has to be more life, and highly advanced civilizations somewhere." Assuming that, sure, we can't see them. But why hasn't some advanced civilization seen us?
- craftyguy 8y ago
  Some thoughts (in no particular order): - some have, and have responded, but we aren't looking for them in the right place and in the right way - humans have only been able to actively send information into space since only about the 1950s (radio waves), and physics dictates that locations 80 light years away are just now starting to see that, provided they are looking in the right location and in the right way (and that they are technologically advanced enough to do so. - It could be that a sufficiently advanced civilization no longer has the capability to receive and transmit long-wave radio communications. Just like many computers now don't have any way to read a floppy disk, or if someone were trying to communicate via smoke signals, you'd be hard pressed to find anyone who could understand it. - Space is so large that if a civilization several hundred light years away (an insignificant fraction of the size of our one galaxy, actually) sent us a message that we received and responded to, it's possible they could have collapsed by the time they receive our response. The converse is also true, they could have 'seen' us and sent a message, and we could collapse before we had a chance to receive it and respond.
  - deleted 8y ago
    [deleted]
- LeftTurnSignal 8y ago
  I always thought that if a civilization was so advanced, why would it spend time interacting with a world like ours? We may feel special, but that's only because we haven't found anything else. If they found hundreds (or more) of worlds like ours, then maybe we're just another dot on their galaxy map. Plus if the media is anything to go by, all we do is shoot each other. Might not be too exciting for a civilization who can travel amongst the stars.
  - JoeAltmaier 8y ago
    That's the subject of about a century of science fiction speculation. The deal is, if we were one among hundreds or thousands, what are the odds nobody at all in any of those other civilizations would want to interact with us? Because we've received zero interactions. Dead silence. Why is that? Well, it takes a lot of energy to broadcast, so they'd have to beam us a message. We're not really looking for beams. Don't even know what they'd look like? Laser pulses? Soliton trains? Neutrino bursts?
    - sliken 8y ago
      Someone would have to be very close (30 light years or so) to have noticed us and have time to signal back. Even among those, likely they would just watch us and then decide if they want to chance contacting a race that has thrown nukes at each other.
      - gehwartzen 8y ago
        To put that in perspective there are about 400 stars within 30 light years of earth and among those stars we have found 26 exoplanets. This radius represents only about 0.00014% of just our own galaxy and an infinitesimaly small portion of the entire universe.
      - ntsplnkv2 8y ago
        According to our knowledge of the universe. And if that is accurate, then essentially we ARE alone in the universe. There simply isn't anything close enough - we'll be enveloped by the sun or some other catastrophe before that happens.

ntsplnkv2 8y ago

Okay that explains why we can't see them. Why can't they see us? All the arguments for life say "the universe is so big there has to be more life, and highly advanced civilizations somewhere." Assuming that, sure, we can't see them. But why hasn't some advanced civilization seen us?

craftyguy 8y ago
Some thoughts (in no particular order): - some have, and have responded, but we aren't looking for them in the right place and in the right way - humans have only been able to actively send information into space since only about the 1950s (radio waves), and physics dictates that locations 80 light years away are just now starting to see that, provided they are looking in the right location and in the right way (and that they are technologically advanced enough to do so. - It could be that a sufficiently advanced civilization no longer has the capability to receive and transmit long-wave radio communications. Just like many computers now don't have any way to read a floppy disk, or if someone were trying to communicate via smoke signals, you'd be hard pressed to find anyone who could understand it. - Space is so large that if a civilization several hundred light years away (an insignificant fraction of the size of our one galaxy, actually) sent us a message that we received and responded to, it's possible they could have collapsed by the time they receive our response. The converse is also true, they could have 'seen' us and sent a message, and we could collapse before we had a chance to receive it and respond.
- deleted 8y ago
  [deleted]
LeftTurnSignal 8y ago
I always thought that if a civilization was so advanced, why would it spend time interacting with a world like ours? We may feel special, but that's only because we haven't found anything else. If they found hundreds (or more) of worlds like ours, then maybe we're just another dot on their galaxy map. Plus if the media is anything to go by, all we do is shoot each other. Might not be too exciting for a civilization who can travel amongst the stars.
- JoeAltmaier 8y ago
  That's the subject of about a century of science fiction speculation. The deal is, if we were one among hundreds or thousands, what are the odds nobody at all in any of those other civilizations would want to interact with us? Because we've received zero interactions. Dead silence. Why is that? Well, it takes a lot of energy to broadcast, so they'd have to beam us a message. We're not really looking for beams. Don't even know what they'd look like? Laser pulses? Soliton trains? Neutrino bursts?
  - sliken 8y ago
    Someone would have to be very close (30 light years or so) to have noticed us and have time to signal back. Even among those, likely they would just watch us and then decide if they want to chance contacting a race that has thrown nukes at each other.
    - gehwartzen 8y ago
      To put that in perspective there are about 400 stars within 30 light years of earth and among those stars we have found 26 exoplanets. This radius represents only about 0.00014% of just our own galaxy and an infinitesimaly small portion of the entire universe.
    - ntsplnkv2 8y ago
      According to our knowledge of the universe. And if that is accurate, then essentially we ARE alone in the universe. There simply isn't anything close enough - we'll be enveloped by the sun or some other catastrophe before that happens.