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It's popular to suggest we don't hear aliens because they all destroyed themselves. But a basic RF link budget calculation shows that even an Arecibo sized ante

It's popular to suggest we don't hear aliens because they all destroyed themselves. But a basic RF link budget calculation shows that even an Arecibo sized antenna pointed perfectly at another Arecibo telescope on an alien planet, and listening/transmitting at the exact right times, could only barely contact one or two of the nearest stars. This fact is buried in all the Fermi Paradox discussions because Fermi's point was the implications of his work on nuclear weapons when he brought up alien contact. It has since been used to make the case for Reagan's Strategic Defense Initiative. Which apparently Elon Musk is now continuing... https://ioc.exchange/@muskfiles https://ioc.exchange/@muskfiles

throw9474 2y ago
The most interesting discussion on Elon's nuclear weapons interception plans was xAI's, https://www.reddit.com/r/ChatGPT/comments/1dgyujd/comment/l8tgf79/ https://www.reddit.com/r/ChatGPT/comments/1dgyujd/comment/l8...
nimish 2y ago
I think people, for both good and bad faith reasons, vastly underestimate how unlikely it would be for any sort of artificial signal to reach us. It would need to be so powerful and so precisely aimed at us that firing randomly into the void would be pointless. We can barely detect the most energetic events in the universe like quasars and gamma ray bursts as it is. And that assumes we could even decode it -- advanced coding uses scrambling techniques that deliberately make the signal look like noise to the uninformed receiver...
- exe34 2y ago
  presumably nowadays we would only aim at stars with a planet with an atmosphere we might at least suspect to be influenced by biology (i.e. contains some gas that couldn't be formed and maintained by known geological processes). so maybe aliens would see oxygen in our atmosphere and aim at us - but you'd still have to get the timing right: we might have been burning witches the last time one message came by and next time we might be in the midst of some other social disturbance.
dTal 2y ago
The Fermi paradox does not merely concern the lack of alien signals - it also notes the peculiarity of the absence of alien spacecraft / visitors. The Milky Way is big, but not so big that it's impossible to traverse generationally. If interstellar spaceflight capable aliens evolved at any time in the galaxy's 13 billion year history other than within the past, say, few million years - a fraction of a percent of the total - then we should expect them to have colonized the galaxy by now. There is 0 evidence that this has happened - no monoliths on the moon, no Dyson sphere signatures visible in our telescopes. Either they're very quiet for some reason, or nobody cracked interstellar travel. That's concerning when it seems perfectly possible and desirable to do. The Milky Way is big, indeed - big enough and old enough that someone should be here.
- pixl97 2y ago
  This, or the Dark Forest theory is correct.
- arp242 2y ago
  > The Milky Way is big, but not so big that it's impossible to traverse generationally. Creating a self-sustained ship is not so easy. And there are tons of failures that can happen, especially over the course of multiple generations. And you won't be able to just "beam down" to some random planet once your interflux quantum capacitor and its two backups fail. Unlikely things happen given enough time. And why would you want to do this in the first place? Would life on such a ship really be all that great? Sounds like the stuff of a depressing dystopian sci-fi novel more than anything else. Dyson spheres seem completely impractical. Just the sheer amount of materials needed alone, never mind the construction effort and maintenance effort. Dyson himself didn't take it very seriously, and I have no idea why anyone else does either.
  - dTal 2y ago
    All very relevant points to why human generation ships are unlikely. Totally irrelevant points as to why, out of the hundreds of billions of planets in the Milky Way, it would appear that not one has evolved an organism capable of spreading out of its gravity well. In general, Life Finds A Way. Life on a ship is depressing? You may as well argue that life in hydrothermal vents would be boring. As for Dyson spheres, don't take the remark so literally. I simply meant that a galaxy-spanning slime mould would probably be visible to our physics, somehow. Life is an entropy engine. Once it gets going, it really gets going. But we appear to live in an improbable oasis in a vast desert.

throw9474 2y ago

The most interesting discussion on Elon's nuclear weapons interception plans was xAI's, https://www.reddit.com/r/ChatGPT/comments/1dgyujd/comment/l8tgf79/ https://www.reddit.com/r/ChatGPT/comments/1dgyujd/comment/l8...

nimish 2y ago

I think people, for both good and bad faith reasons, vastly underestimate how unlikely it would be for any sort of artificial signal to reach us. It would need to be so powerful and so precisely aimed at us that firing randomly into the void would be pointless. We can barely detect the most energetic events in the universe like quasars and gamma ray bursts as it is. And that assumes we could even decode it -- advanced coding uses scrambling techniques that deliberately make the signal look like noise to the uninformed receiver...

exe34 2y ago
presumably nowadays we would only aim at stars with a planet with an atmosphere we might at least suspect to be influenced by biology (i.e. contains some gas that couldn't be formed and maintained by known geological processes). so maybe aliens would see oxygen in our atmosphere and aim at us - but you'd still have to get the timing right: we might have been burning witches the last time one message came by and next time we might be in the midst of some other social disturbance.

dTal 2y ago

The Fermi paradox does not merely concern the lack of alien signals - it also notes the peculiarity of the absence of alien spacecraft / visitors. The Milky Way is big, but not so big that it's impossible to traverse generationally. If interstellar spaceflight capable aliens evolved at any time in the galaxy's 13 billion year history other than within the past, say, few million years - a fraction of a percent of the total - then we should expect them to have colonized the galaxy by now. There is 0 evidence that this has happened - no monoliths on the moon, no Dyson sphere signatures visible in our telescopes. Either they're very quiet for some reason, or nobody cracked interstellar travel. That's concerning when it seems perfectly possible and desirable to do. The Milky Way is big, indeed - big enough and old enough that someone should be here.

pixl97 2y ago
This, or the Dark Forest theory is correct.
arp242 2y ago
> The Milky Way is big, but not so big that it's impossible to traverse generationally. Creating a self-sustained ship is not so easy. And there are tons of failures that can happen, especially over the course of multiple generations. And you won't be able to just "beam down" to some random planet once your interflux quantum capacitor and its two backups fail. Unlikely things happen given enough time. And why would you want to do this in the first place? Would life on such a ship really be all that great? Sounds like the stuff of a depressing dystopian sci-fi novel more than anything else. Dyson spheres seem completely impractical. Just the sheer amount of materials needed alone, never mind the construction effort and maintenance effort. Dyson himself didn't take it very seriously, and I have no idea why anyone else does either.
- dTal 2y ago
  All very relevant points to why human generation ships are unlikely. Totally irrelevant points as to why, out of the hundreds of billions of planets in the Milky Way, it would appear that not one has evolved an organism capable of spreading out of its gravity well. In general, Life Finds A Way. Life on a ship is depressing? You may as well argue that life in hydrothermal vents would be boring. As for Dyson spheres, don't take the remark so literally. I simply meant that a galaxy-spanning slime mould would probably be visible to our physics, somehow. Life is an entropy engine. Once it gets going, it really gets going. But we appear to live in an improbable oasis in a vast desert.