7 ms·

SETI and Signal Leakage: Where Do Our Transmissions Go?

54 points by andyjohnson0 4y ago

h2odragon 4y ago
If we were at the far end of these transmission, at one of these background stars, could we discern the signal as signal when it arrives? SETI fans don't seem to want to answer that.
- Vanit 4y ago
  Joe Scott did a video on this last year: https://youtu.be/ISXbTBKl4aE https://youtu.be/ISXbTBKl4aE He's just a science enthusiast, but it touches all the points it needs to.
  - ZunarJ5 4y ago
    Love Joe Scott. He's one of the few channels I watch.
    - p1mrx 4y ago
      Joe Scott is like listening to ChatGPT. In most videos you'll find confidently wrong stuff like "we communicate mostly through satellites these days ... they're only having to go up you know 100 or so kilometers."
- Mistletoe 4y ago
  https://www.sciencefocus.com/space/how-far-from-earth-could-aliens-detect-our-radio-signals/ https://www.sciencefocus.com/space/how-far-from-earth-could-... Strongest radar we have ever made could do perhaps a few hundred light years? The Milky Way is 100,000 light years across and there are only about 59,000 stars visible with a telescope within 100 light years of earth. I think it would take a very charitable reading of the Drake equation to believe our signals even met intelligent life capable of receiving them.
- stolenmerch 4y ago
  Perhaps if some advanced civilization were able to modulate radio pulsars. But it's not like we're monitoring across a wide bandwidth, so they'd need to transmit at the specific narrow band that we listen to. SETI is fun to think about and experiment with but it always strikes me as bit of a fool's errand.
signalioto 4y ago
What's the best way for a layman to send out my own lasting signal? Perhaps a small tube creating a Radiolaser?
- OnlyMortal 4y ago
  Firstly you need a target to send it to. Secondly you need to handle the rotation of the Earth so that you remain on target. Thirdly, you need to send a powerful enough signal that it can be detected above the background noise at that target. The idea that aliens can pickup a radio station or TV station doesn’t seem likely to me. The rotation of the Earth would sweep that signal across them. They might be able to detect “noise” at unusual frequencies but it wouldn’t appear coherent.
  - signalioto 4y ago
    If I just have a basic radiodish, send out a kilowatt of signal and keep it relatively stable, how far away someone could make it out though? What if we as humans want to send a signal? Would we just detonate a bomb in space? Couldn't it be possible that someone out there figured out how to travel tremendously fast but is just not able to find anyone?
    - flangola7 4y ago
      > Couldn't it be possible that someone out there figured out how to travel tremendously fast but is just not able to find anyone? I find this doubtful because they could travel outward in a sphere, touching every celestial object in the universe as they go.
      - signalioto 4y ago
        They still could have some lifetime limitations. Like only one flight per month. Or they know how to do a very fast straight line but nothing local. Therefore needing to recharge and shot themselfs one waypoint after the next.
    - 4y ago
ModernMech 4y ago
The answer is, they go to Vega :P As you can tell, I just watched "Contact" last night as it came onto HBO for the first time in forever.
drexlspivey 4y ago
I wonder how likely is it for an advanced civilization to exist out there without having discovered electromagnetism. In the book “Project Hail Mary” by Andy Weir, Eridians who are at a similar stage as humans were oblivious to Ionizing Radiation and Relativity.
- PM_me_your_math 4y ago
  That was us until the early 1800s. So I would say likely.
  - trompetenaccoun 4y ago
    What's the definition of "advanced" here? Also our sample size is 1. This is all speculation, none of it has any practical meaning since we know nothing about even where life on earth came from. Let alone if it exists elsewhere. I love science fiction but we should not get it confused with reality.
- boringuser2 4y ago
  Not buying it. Humans are barely intelligent enough to be at any level of development. We don't have great apes beat by as much as people think. It's conceivable to me that we are the absolute minimum level of intellect to be a species that can develop tools allowing us to escape our ancestral environment.
  - lukeschlather 4y ago
    It's important to note first of all that we haven't meaningfully escaped Earth's gravity well. Our models seem to make it possible, I'm sure it can be done, I'm sure we can even get to other stars without changing our understanding of physics. At the same time the notion of "absolute minimum level of intellect" is somewhat poorly defined. It's somewhat hard to imagine, but there could be a set of physics theories that don't include relativity or gravity or any of our familiar concepts, but still enable interstellar travel. Maybe another civilization skipped our fragmentary and incorrect understanding and hit directly on a unified field theory. Or maybe we both have fragmentary and incorrect understandings, both are essentially wrong in every way, and yet they are close enough for practical purposes. Is the civilization which developed the more practical model of physics "smarter" or just lucky? Does "smarter" mean that you develop a model of physics which is closer to ground truth, or one that enables you to build better spacecraft, or one that enables you to build better computers?
0xDEF 4y ago
Our modern omni-directional digital broadcasts probably don't go far. But what about our focused beams from airport and weather radars?
- samus 4y ago
  These beams are sweeping across the sky, therefore there will only be very brief windows of exposure for any observer in the sky. Since our planet rotates, in my lay opinion the chances are even lower that a target in deep space will get enough regular exposure to analyze even strong signals accidentally sent out from Earth. The Deep Space Network has to use three big rotating dishes to keep sending to and receiving from a direction in the outer solar system. These signals have been going for a long time now, therefore it might be a promising approach to focus SETI's resources on the stars where these signals might have ended up (more details in the article)
- poulpy123 4y ago
  focused beams have the same problem than the other ones, the power decrease in r^2.
CommieBobDole 4y ago
I figure if you want to send out a signal that can be distinguished from background radiation at tens or hundreds of light years, your best bet would be to detonate gigaton-scale nukes in space in some sort of mathematically interesting pattern. Or manufacture a few billion tons of some exotic element that doesn't exist in nature and dump it into the sun on a regular basis. But it looks like somebody else might have already had that idea. https://en.wikipedia.org/wiki/Przybylski%27s_Star https://en.wikipedia.org/wiki/Przybylski%27s_Star
- corobo 4y ago
  Now I'm imagining the planet exploding and some aliens 30 million years from now "What was that flash??" "Dunno" The end of our legacy haha. We really should get a backup planet sorted out at some point once we've fixed gestures at everything
- metadat 4y ago
  Contact (1996) solved this nicely: Send out a sequence of prime numbers.
  - gs17 4y ago
    The problem isn't making an interesting pattern, it's the medium of that pattern at a power level that is detectable when it reaches them. Flashing prime numbers at stars with a 60W bulb isn't going to get heard.
- JPLeRouzic 4y ago
  Does this explain why we didn't detect Aliens with SETI? Because their signals would be under the noise level (except for a few stars)? Indeed those stars that close enough to our interstellar probes will be also informed of our existence. "The transmissions to Voyager 2, Pioneer 10, and Pioneer 11 have already encountered at least one star, while those to Voyager 1 and New Horizons will encounter their first stars in the near future." https://arxiv.org/pdf/2304.07400.pdf https://arxiv.org/pdf/2304.07400.pdf
mcv 4y ago
Ages ago, I learned that our best receivers would not be able to detect our most powerful radio/TV broadcasts from more than half a lightyear away. I lack the knowledge to determine if that's true, but if it is, all those romantic notions of aliens learning about us from our radio/TV shows will sadly (or fortunately) never be true. This article doesn't explicitly point out the distinction between broadcast (which taper off rapidly in power) and narrow beam signals (which lose far less power over distance), but it's pretty clear that it is largely about that distinction. It lists signals aimed at specific spacecraft that hit only a limited number of stars. That tighter beam hopefully means a significant signal will be detectable there. It's cool that they calculate when the return signal might arrive here. It would have been even cooler if they'd calculated how strong the signal would be when it arrives at that star. But it's possible that's far too uncertain to determine; stars near the edge of the beam probably receive far less power than those in the center.

54 points by andyjohnson0 4y ago

If we were at the far end of these transmission, at one of these background stars, could we discern the signal as signal when it arrives? SETI fans don't seem to want to answer that.

Vanit 4y ago
Joe Scott did a video on this last year: https://youtu.be/ISXbTBKl4aE https://youtu.be/ISXbTBKl4aE He's just a science enthusiast, but it touches all the points it needs to.
- ZunarJ5 4y ago
  Love Joe Scott. He's one of the few channels I watch.
  - p1mrx 4y ago
    Joe Scott is like listening to ChatGPT. In most videos you'll find confidently wrong stuff like "we communicate mostly through satellites these days ... they're only having to go up you know 100 or so kilometers."
Mistletoe 4y ago
https://www.sciencefocus.com/space/how-far-from-earth-could-aliens-detect-our-radio-signals/ https://www.sciencefocus.com/space/how-far-from-earth-could-... Strongest radar we have ever made could do perhaps a few hundred light years? The Milky Way is 100,000 light years across and there are only about 59,000 stars visible with a telescope within 100 light years of earth. I think it would take a very charitable reading of the Drake equation to believe our signals even met intelligent life capable of receiving them.
stolenmerch 4y ago
Perhaps if some advanced civilization were able to modulate radio pulsars. But it's not like we're monitoring across a wide bandwidth, so they'd need to transmit at the specific narrow band that we listen to. SETI is fun to think about and experiment with but it always strikes me as bit of a fool's errand.

signalioto 4y ago

What's the best way for a layman to send out my own lasting signal? Perhaps a small tube creating a Radiolaser?

OnlyMortal 4y ago
Firstly you need a target to send it to. Secondly you need to handle the rotation of the Earth so that you remain on target. Thirdly, you need to send a powerful enough signal that it can be detected above the background noise at that target. The idea that aliens can pickup a radio station or TV station doesn’t seem likely to me. The rotation of the Earth would sweep that signal across them. They might be able to detect “noise” at unusual frequencies but it wouldn’t appear coherent.
- signalioto 4y ago
  If I just have a basic radiodish, send out a kilowatt of signal and keep it relatively stable, how far away someone could make it out though? What if we as humans want to send a signal? Would we just detonate a bomb in space? Couldn't it be possible that someone out there figured out how to travel tremendously fast but is just not able to find anyone?
  - flangola7 4y ago
    > Couldn't it be possible that someone out there figured out how to travel tremendously fast but is just not able to find anyone? I find this doubtful because they could travel outward in a sphere, touching every celestial object in the universe as they go.
    - signalioto 4y ago
      They still could have some lifetime limitations. Like only one flight per month. Or they know how to do a very fast straight line but nothing local. Therefore needing to recharge and shot themselfs one waypoint after the next.
  - 4y ago

ModernMech 4y ago

The answer is, they go to Vega :P As you can tell, I just watched "Contact" last night as it came onto HBO for the first time in forever.

drexlspivey 4y ago

I wonder how likely is it for an advanced civilization to exist out there without having discovered electromagnetism. In the book “Project Hail Mary” by Andy Weir, Eridians who are at a similar stage as humans were oblivious to Ionizing Radiation and Relativity.

PM_me_your_math 4y ago
That was us until the early 1800s. So I would say likely.
- trompetenaccoun 4y ago
  What's the definition of "advanced" here? Also our sample size is 1. This is all speculation, none of it has any practical meaning since we know nothing about even where life on earth came from. Let alone if it exists elsewhere. I love science fiction but we should not get it confused with reality.
boringuser2 4y ago
Not buying it. Humans are barely intelligent enough to be at any level of development. We don't have great apes beat by as much as people think. It's conceivable to me that we are the absolute minimum level of intellect to be a species that can develop tools allowing us to escape our ancestral environment.
- lukeschlather 4y ago
  It's important to note first of all that we haven't meaningfully escaped Earth's gravity well. Our models seem to make it possible, I'm sure it can be done, I'm sure we can even get to other stars without changing our understanding of physics. At the same time the notion of "absolute minimum level of intellect" is somewhat poorly defined. It's somewhat hard to imagine, but there could be a set of physics theories that don't include relativity or gravity or any of our familiar concepts, but still enable interstellar travel. Maybe another civilization skipped our fragmentary and incorrect understanding and hit directly on a unified field theory. Or maybe we both have fragmentary and incorrect understandings, both are essentially wrong in every way, and yet they are close enough for practical purposes. Is the civilization which developed the more practical model of physics "smarter" or just lucky? Does "smarter" mean that you develop a model of physics which is closer to ground truth, or one that enables you to build better spacecraft, or one that enables you to build better computers?

0xDEF 4y ago

Our modern omni-directional digital broadcasts probably don't go far. But what about our focused beams from airport and weather radars?

samus 4y ago
These beams are sweeping across the sky, therefore there will only be very brief windows of exposure for any observer in the sky. Since our planet rotates, in my lay opinion the chances are even lower that a target in deep space will get enough regular exposure to analyze even strong signals accidentally sent out from Earth. The Deep Space Network has to use three big rotating dishes to keep sending to and receiving from a direction in the outer solar system. These signals have been going for a long time now, therefore it might be a promising approach to focus SETI's resources on the stars where these signals might have ended up (more details in the article)
poulpy123 4y ago
focused beams have the same problem than the other ones, the power decrease in r^2.

CommieBobDole 4y ago

I figure if you want to send out a signal that can be distinguished from background radiation at tens or hundreds of light years, your best bet would be to detonate gigaton-scale nukes in space in some sort of mathematically interesting pattern. Or manufacture a few billion tons of some exotic element that doesn't exist in nature and dump it into the sun on a regular basis. But it looks like somebody else might have already had that idea. https://en.wikipedia.org/wiki/Przybylski%27s_Star https://en.wikipedia.org/wiki/Przybylski%27s_Star

corobo 4y ago
Now I'm imagining the planet exploding and some aliens 30 million years from now "What was that flash??" "Dunno" The end of our legacy haha. We really should get a backup planet sorted out at some point once we've fixed gestures at everything
metadat 4y ago
Contact (1996) solved this nicely: Send out a sequence of prime numbers.
- gs17 4y ago
  The problem isn't making an interesting pattern, it's the medium of that pattern at a power level that is detectable when it reaches them. Flashing prime numbers at stars with a 60W bulb isn't going to get heard.
JPLeRouzic 4y ago
Does this explain why we didn't detect Aliens with SETI? Because their signals would be under the noise level (except for a few stars)? Indeed those stars that close enough to our interstellar probes will be also informed of our existence. "The transmissions to Voyager 2, Pioneer 10, and Pioneer 11 have already encountered at least one star, while those to Voyager 1 and New Horizons will encounter their first stars in the near future." https://arxiv.org/pdf/2304.07400.pdf https://arxiv.org/pdf/2304.07400.pdf

mcv 4y ago

Ages ago, I learned that our best receivers would not be able to detect our most powerful radio/TV broadcasts from more than half a lightyear away. I lack the knowledge to determine if that's true, but if it is, all those romantic notions of aliens learning about us from our radio/TV shows will sadly (or fortunately) never be true. This article doesn't explicitly point out the distinction between broadcast (which taper off rapidly in power) and narrow beam signals (which lose far less power over distance), but it's pretty clear that it is largely about that distinction. It lists signals aimed at specific spacecraft that hit only a limited number of stars. That tighter beam hopefully means a significant signal will be detectable there. It's cool that they calculate when the return signal might arrive here. It would have been even cooler if they'd calculated how strong the signal would be when it arrives at that star. But it's possible that's far too uncertain to determine; stars near the edge of the beam probably receive far less power than those in the center.