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"Look at it this way: the sun to that system barely emits enough energy to make that planet visible to our technology. So, if that planet wanted to send us dat

"Look at it this way: the sun to that system barely emits enough energy to make that planet visible to our technology. So, if that planet wanted to send us data, they would have to send as much energy as gets reflected by that planet in our direction. Since you said "as advanced as ours": We're not capable of producing that much power. Not even remotely. So they're not capable of doing that, either. A star is amazingly powerful. Let's look at this way. The estimated power of the sun is something like 1026 W." Thread on SO here: https://space.stackexchange.com/questions/22617/can-we-communicate-with-tau-ceti https://space.stackexchange.com/questions/22617/can-we-commu...

O5vYtytb 5y ago
If I understand correctly, it's not the light reflected off the exoplanet that we detect, it's the slight dimming of the stars light as the exoplanet transitions between the star and our telescope. I'm not sure what this has to do with a communications link though. It's not like we need as much energy as a star, we can use a directional link like a laser. Sure it'd still need to be massive but while I don't have the math in front of me, it seems like something we could build.
- throw1234651234 5y ago
  You are talking about detecting planets as they revolve around the star. As you said, if the planet rotates on an axis that "blocks" a tiny, tiny fraction of the star as we observe it, we see the dimming (that goes away as the planet passes) and can assume a planet and some parameters. You are also right that the conversation is about COMMUNICATION: 1. You either dim the star with a Dyson swarm, or 2. You pulse more power than the star outputs as background noise briefly Neither is all that viable.
  - O5vYtytb 5y ago
    Why can't you use a laser with a relatively high power? Should be easier to differentiate that from background and star light? Or something more exotic like sweeping wavelengths.
marcosdumay 5y ago
Hum... All the other answers on that thread are variations of "yes, we could, here's an example of how" with the examples varying from one widely impractical idea to "here is how we do something similar by accident today, we just have to control it". If we had to overpower the Sun to communicate, we wouldn't use radio on Earth either.
- throw1234651234 5y ago
  Having followed that answer for years and read quite a bit, I am fairly certain that the "yes, but" answers are wrong. It's as simple as "you can't see a flashlight when it's being flicked on and off behind a lighthouse lamp". I am very interested in the topic.
  - marcosdumay 5y ago
    Well, I'd suggest a basic introduction to optics. You seem unaware of the existence of lenses and mirrors. "What kind of mirror we would need to send a signal 10 light years away" is a much more reasonable question. And one of the answers there is about it.
    - throw1234651234 5y ago
      You mean mirror that's out of the way of the sun and is huge, or a mirror swarm. Do elaborate how you imagine this working in practice.
  - ninjanomnom 5y ago
    If we had to emit light just like a flashlight vs a lighthouse, aka roughly equivalent wavelengths, you'd be right, however we only have to beat the sun in a single wavelength. An extreme uv laser is probably the easiest option there. We also only need to beat the sun's output in a single pinpoint (in cosmic scale) Also to damage the example a bit, we can easily detect a flashlight shining from behind a lighthouse. Our eyes are just logarithmic and suck at detecting smaller absolute differences like that. Isaac Arthur does a good video on this topic and talks about some of the specifics of such a beacon starting at around 14 minutes https://youtu.be/DHoOjIEcRV8?t=829 https://youtu.be/DHoOjIEcRV8?t=829

O5vYtytb 5y ago

If I understand correctly, it's not the light reflected off the exoplanet that we detect, it's the slight dimming of the stars light as the exoplanet transitions between the star and our telescope. I'm not sure what this has to do with a communications link though. It's not like we need as much energy as a star, we can use a directional link like a laser. Sure it'd still need to be massive but while I don't have the math in front of me, it seems like something we could build.

throw1234651234 5y ago
You are talking about detecting planets as they revolve around the star. As you said, if the planet rotates on an axis that "blocks" a tiny, tiny fraction of the star as we observe it, we see the dimming (that goes away as the planet passes) and can assume a planet and some parameters. You are also right that the conversation is about COMMUNICATION: 1. You either dim the star with a Dyson swarm, or 2. You pulse more power than the star outputs as background noise briefly Neither is all that viable.
- O5vYtytb 5y ago
  Why can't you use a laser with a relatively high power? Should be easier to differentiate that from background and star light? Or something more exotic like sweeping wavelengths.

marcosdumay 5y ago

Hum... All the other answers on that thread are variations of "yes, we could, here's an example of how" with the examples varying from one widely impractical idea to "here is how we do something similar by accident today, we just have to control it". If we had to overpower the Sun to communicate, we wouldn't use radio on Earth either.

throw1234651234 5y ago
Having followed that answer for years and read quite a bit, I am fairly certain that the "yes, but" answers are wrong. It's as simple as "you can't see a flashlight when it's being flicked on and off behind a lighthouse lamp". I am very interested in the topic.
- marcosdumay 5y ago
  Well, I'd suggest a basic introduction to optics. You seem unaware of the existence of lenses and mirrors. "What kind of mirror we would need to send a signal 10 light years away" is a much more reasonable question. And one of the answers there is about it.
  - throw1234651234 5y ago
    You mean mirror that's out of the way of the sun and is huge, or a mirror swarm. Do elaborate how you imagine this working in practice.
- ninjanomnom 5y ago
  If we had to emit light just like a flashlight vs a lighthouse, aka roughly equivalent wavelengths, you'd be right, however we only have to beat the sun in a single wavelength. An extreme uv laser is probably the easiest option there. We also only need to beat the sun's output in a single pinpoint (in cosmic scale) Also to damage the example a bit, we can easily detect a flashlight shining from behind a lighthouse. Our eyes are just logarithmic and suck at detecting smaller absolute differences like that. Isaac Arthur does a good video on this topic and talks about some of the specifics of such a beacon starting at around 14 minutes https://youtu.be/DHoOjIEcRV8?t=829 https://youtu.be/DHoOjIEcRV8?t=829