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Why aliens might already know that humans exist

7 points by gardenfelder 3y ago

gardenfelder 3y ago
"Alien astronomers might be looking in our direction from distant planets. What would they see?"
RecycledEle 3y ago
If an alien race had our technology and attention to SETI, how far away could they be and know that we exist? Every time I ask this question, I hear astounding lack of knowledge about how little we have done to look for aliens, or I hear amazing lack of knowledge about the distances involved.
- az09mugen 3y ago
  My 2 cents : Basically the Earth started emitting radio transmissions roughly ~100 years ago. Every sent transmission travels at light speed and goes also involuntarily into deep space (even if not always). So, the farthest point from Earth that we could have emitted involuntarily is around 100 light years away. If in this "bubble" of 200 light years of diameter with the Earth at the center there is an alien civilization with SETI-like tech, they could detect our encoded signals and deduce they are not natural, hence detect us.
  - RecycledEle 3y ago
    I appreciate your comment, but I have to respectfully say this is the kind of lazy thinking I am complaining about. Yes, we have been emitting radio waves for 100 years, but 100 light-years away, how strong are those radio waves? Remember the inverse square law. Even if you magically knew the format, could you decode them? If you did not know the format, could you detect something above the normal bacground? If we did think it was above the background, would we believe it was artificial? NASA has a very high bar for what they think it artificial.
- ksaj 3y ago
  I wouldn't say we do so little looking for life in space. Our preoccupation with looking for the things that brought what we needed for life to Earth before life came about here is akin to looking for life in space. We are always looking for what we believe are the indicators that would make life possible. We say that it is to understand our own origin, but the side effect of that is that if we find enough of it in space, we'll study it for its potential for life, just as we are doing on Mars right now.
ksaj 3y ago
When one of the space vehicles was doing a swing past Earth, for speed, Carl Sagan asked NASA to turn their equipment to the Earth and see what they could detect. The surprising outcome was that the tools aboard that particular probe was unable to determine life on Earth, even when swinging in orbit around it. Mind you, that wasn't it's original mission plan anyway. But it shows that you have to look for very specific things, and as of yet we have not detected life on Earth from Space (other than our satellites, but that's a given).

7 points by gardenfelder 3y ago

"Alien astronomers might be looking in our direction from distant planets. What would they see?"

If an alien race had our technology and attention to SETI, how far away could they be and know that we exist? Every time I ask this question, I hear astounding lack of knowledge about how little we have done to look for aliens, or I hear amazing lack of knowledge about the distances involved.

az09mugen 3y ago
My 2 cents : Basically the Earth started emitting radio transmissions roughly ~100 years ago. Every sent transmission travels at light speed and goes also involuntarily into deep space (even if not always). So, the farthest point from Earth that we could have emitted involuntarily is around 100 light years away. If in this "bubble" of 200 light years of diameter with the Earth at the center there is an alien civilization with SETI-like tech, they could detect our encoded signals and deduce they are not natural, hence detect us.
- RecycledEle 3y ago
  I appreciate your comment, but I have to respectfully say this is the kind of lazy thinking I am complaining about. Yes, we have been emitting radio waves for 100 years, but 100 light-years away, how strong are those radio waves? Remember the inverse square law. Even if you magically knew the format, could you decode them? If you did not know the format, could you detect something above the normal bacground? If we did think it was above the background, would we believe it was artificial? NASA has a very high bar for what they think it artificial.
ksaj 3y ago
I wouldn't say we do so little looking for life in space. Our preoccupation with looking for the things that brought what we needed for life to Earth before life came about here is akin to looking for life in space. We are always looking for what we believe are the indicators that would make life possible. We say that it is to understand our own origin, but the side effect of that is that if we find enough of it in space, we'll study it for its potential for life, just as we are doing on Mars right now.

ksaj 3y ago

When one of the space vehicles was doing a swing past Earth, for speed, Carl Sagan asked NASA to turn their equipment to the Earth and see what they could detect. The surprising outcome was that the tools aboard that particular probe was unable to determine life on Earth, even when swinging in orbit around it. Mind you, that wasn't it's original mission plan anyway. But it shows that you have to look for very specific things, and as of yet we have not detected life on Earth from Space (other than our satellites, but that's a given).