3 ms·

Not necessarily attempts to communicate with Earth. Aliens might be using beamed propulsion for solar sails, for example.

mcv 5y ago
This is probably the only good reason I can think of why they might point a laser directly at us. They have no idea we're here, listening. The chances that we happen to be listening at exactly the right moment is miniscule. For the same reason, I don't have a lot of hope that SETI using radiotelescopes will ever find anything. But using lasers to power a ship or probe headed to our solar system could make sense. Well, maybe not from Tabby's Star; it's over 1000 ly away. I'm sure they have plenty of closer targets to send their probes to.
- MattPalmer1086 5y ago
  Also just powering craft in their own system, doesn't have to be interstellar targets. See this post for an interesting take on how we could use it in the solar system. https://www.centauri-dreams.org/2022/01/11/interstellar-reach-the-challenge-of-beamed-energy/ https://www.centauri-dreams.org/2022/01/11/interstellar-reac...
  - mcv 5y ago
    Yeah, but then what's the likelihood of aiming directly at us? Even a fraction of a degree off and we won't see it.
    - MattPalmer1086 5y ago
      I'd say higher for intra system craft, as you'd expect a much higher volume of such craft pointing at a greater number of targets at different orbital positions than interstellar targets.
    - hotpotamus 5y ago
      If you have a decent understanding of the planets in a system you could potentially time your observations to when planets are in alignments that would beam lasers / radio waves your way. It's possible that you could pick up directed in-system communications that are overshooting their destinations rather than broadcasts intended for potential interstellar neighbors.
- matthewdgreen 5y ago
  >I'm sure they have plenty of closer targets to send their probes to. And perhaps they already have: https://arxiv.org/pdf/2111.01208.pdf https://arxiv.org/pdf/2111.01208.pdf
- cma 5y ago
  It doesn't have to be directly at us, there is a misconception that lasers don't spread, but they do, the inverse square law even still applies to them at big distances.

mcv 5y ago

This is probably the only good reason I can think of why they might point a laser directly at us. They have no idea we're here, listening. The chances that we happen to be listening at exactly the right moment is miniscule. For the same reason, I don't have a lot of hope that SETI using radiotelescopes will ever find anything. But using lasers to power a ship or probe headed to our solar system could make sense. Well, maybe not from Tabby's Star; it's over 1000 ly away. I'm sure they have plenty of closer targets to send their probes to.

MattPalmer1086 5y ago
Also just powering craft in their own system, doesn't have to be interstellar targets. See this post for an interesting take on how we could use it in the solar system. https://www.centauri-dreams.org/2022/01/11/interstellar-reach-the-challenge-of-beamed-energy/ https://www.centauri-dreams.org/2022/01/11/interstellar-reac...
- mcv 5y ago
  Yeah, but then what's the likelihood of aiming directly at us? Even a fraction of a degree off and we won't see it.
  - MattPalmer1086 5y ago
    I'd say higher for intra system craft, as you'd expect a much higher volume of such craft pointing at a greater number of targets at different orbital positions than interstellar targets.
  - hotpotamus 5y ago
    If you have a decent understanding of the planets in a system you could potentially time your observations to when planets are in alignments that would beam lasers / radio waves your way. It's possible that you could pick up directed in-system communications that are overshooting their destinations rather than broadcasts intended for potential interstellar neighbors.
matthewdgreen 5y ago
>I'm sure they have plenty of closer targets to send their probes to. And perhaps they already have: https://arxiv.org/pdf/2111.01208.pdf https://arxiv.org/pdf/2111.01208.pdf
cma 5y ago
It doesn't have to be directly at us, there is a misconception that lasers don't spread, but they do, the inverse square law even still applies to them at big distances.