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Please excuse my complete ignorance - this is something that continues to perplex me no matter how many times I hear it explained and I may sound like a complet

Please excuse my complete ignorance - this is something that continues to perplex me no matter how many times I hear it explained and I may sound like a complete idiot here. Can someone explain how this would work in layman's terms? Let's say that life on another planet 150 million billion miles away wanted to send us a message. So that's 25,000 light years away. They send us one single 1 minute duration message at t=0 and that message travels at the speed of light as an example. And let's just say t=25000 happens to be today. Does that mean that we have a one minute window to intercept part of the message otherwise it's lost? If so, let's say the life on that planet was persistent and continued to send messages continuously directly to us and no other planets for 500 years. Then I would assume we have a 500 year period to play with. If they started sending signals let's say 10,000 years ago, it seems we have absolutely no chance to receive the message unless this program is operational for the next 15,000 years or so. But our odds of receiving an intelligent signal is vastly higher simply due to the number of planets in our galaxy. Is my understanding remotely correct?

MattConfluence 11y ago
Sounds about right. Frank Drake created his famous equation [1] to try to quantify the probability of detecting ETI, but you do need to make guesses at some of the inputs. [1] https://en.wikipedia.org/wiki/Drake_equation https://en.wikipedia.org/wiki/Drake_equation
- nsajko 11y ago
  Relevant xkcd: http://www.xkcd.com/384/ http://www.xkcd.com/384/
jessriedel 11y ago
Traditionally, SETI is not specialized to messages intentionally crafted for us (or, in fact, necessarily crafted for anyone). It's just a search for radio transmissions that are unlikely to have been created by natural sources using various statistical techniques. Even for intentional messages, it's certainly conceivable that another civilization with sufficient power simply transmits the message in all direction continuously.
- scrumper 11y ago
  Even for intentional messages, it's certainly conceivable that another civilization with sufficient power simply transmits the message in all direction continuously. I think that scenario would imply a relative scarcity of intelligent life: after all, if a space-faring civilization needs to transmit powerful, omnidirectional signals in the blind, it must be pretty lonely. Maybe, just maybe, the fact that we're not seeing much is actually indicative of a fairly rich sea of life in the galaxy, communicating point-to-point with each other. Not so much to randomly overhear in that world.
  - RALaBarge 11y ago
    Personally, I am willing to bet that all intelligent life will end up being quite lonely. Unless we find ways to bend space, there is little chance of us ever getting out of our local solar system, let alone galaxy or the local galactic cluster. I am a big fan of science and science fiction, do not get me wrong. I do feel that technology evolves and will surprise even the most tech savvy, but to violate faster than light travel seems more far fetched than any theory out there to me.
    - bhc3 11y ago
      I'm expecting somewhere way down the road, scientists will unlock the secrets to prolonging our lives for nearly forever. They'll stop the telomeres from degrading, come up with ways to address cancer quickly and effectively, etc. At the same time, space travel technology will also have been advanced, allowing for self-sustaining spacecraft that offer protection against the harsh environment of outer space. At that point, you can imagine that a hearty band of explorers will undertake a mission of leaving our solar system and exploring way beyond our world. Who knows how far they could get. These are the sorts of advances I can imagine becoming real many generations from now. I wouldn't underestimate our capacity to make it happen.
      - S4M 11y ago
        If you want to speculate, how about the possibility of uploading people's mind to a robot? Let's say that we are able to send outer space a bunch of self replicating robots (they can travel to various planets and build a copy of themselves using the raw materials they can find there). After some time, we have lots of robots at many points in space, then you make a copy of your mind and send it at the speed of light to those robots. Because of the self replicating nature of the thing, we can have lots of robots so anybody who wants to can upload his/her mind to one of them. That way we have a non risky an relatively cheap way to explore the galaxy - it would just take couple of thousands of years to have everything set up.
oh_sigh 11y ago
Due to the expansion of spacetime during those 25,000 years, we would have slightly longer than 1 minute to receive the signal, but it would be so insignificant that you might as well call it a minute.

MattConfluence 11y ago

Sounds about right. Frank Drake created his famous equation [1] to try to quantify the probability of detecting ETI, but you do need to make guesses at some of the inputs. [1] https://en.wikipedia.org/wiki/Drake_equation https://en.wikipedia.org/wiki/Drake_equation

nsajko 11y ago
Relevant xkcd: http://www.xkcd.com/384/ http://www.xkcd.com/384/

jessriedel 11y ago

Traditionally, SETI is not specialized to messages intentionally crafted for us (or, in fact, necessarily crafted for anyone). It's just a search for radio transmissions that are unlikely to have been created by natural sources using various statistical techniques. Even for intentional messages, it's certainly conceivable that another civilization with sufficient power simply transmits the message in all direction continuously.

scrumper 11y ago
Even for intentional messages, it's certainly conceivable that another civilization with sufficient power simply transmits the message in all direction continuously. I think that scenario would imply a relative scarcity of intelligent life: after all, if a space-faring civilization needs to transmit powerful, omnidirectional signals in the blind, it must be pretty lonely. Maybe, just maybe, the fact that we're not seeing much is actually indicative of a fairly rich sea of life in the galaxy, communicating point-to-point with each other. Not so much to randomly overhear in that world.
- RALaBarge 11y ago
  Personally, I am willing to bet that all intelligent life will end up being quite lonely. Unless we find ways to bend space, there is little chance of us ever getting out of our local solar system, let alone galaxy or the local galactic cluster. I am a big fan of science and science fiction, do not get me wrong. I do feel that technology evolves and will surprise even the most tech savvy, but to violate faster than light travel seems more far fetched than any theory out there to me.
  - bhc3 11y ago
    I'm expecting somewhere way down the road, scientists will unlock the secrets to prolonging our lives for nearly forever. They'll stop the telomeres from degrading, come up with ways to address cancer quickly and effectively, etc. At the same time, space travel technology will also have been advanced, allowing for self-sustaining spacecraft that offer protection against the harsh environment of outer space. At that point, you can imagine that a hearty band of explorers will undertake a mission of leaving our solar system and exploring way beyond our world. Who knows how far they could get. These are the sorts of advances I can imagine becoming real many generations from now. I wouldn't underestimate our capacity to make it happen.
    - S4M 11y ago
      If you want to speculate, how about the possibility of uploading people's mind to a robot? Let's say that we are able to send outer space a bunch of self replicating robots (they can travel to various planets and build a copy of themselves using the raw materials they can find there). After some time, we have lots of robots at many points in space, then you make a copy of your mind and send it at the speed of light to those robots. Because of the self replicating nature of the thing, we can have lots of robots so anybody who wants to can upload his/her mind to one of them. That way we have a non risky an relatively cheap way to explore the galaxy - it would just take couple of thousands of years to have everything set up.

oh_sigh 11y ago

Due to the expansion of spacetime during those 25,000 years, we would have slightly longer than 1 minute to receive the signal, but it would be so insignificant that you might as well call it a minute.