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So the pyramids are visible out to 3000 light years away if the aliens have extremely powerful optical telescopes. More recent developments, like satellites, m

So the pyramids are visible out to 3000 light years away if the aliens have extremely powerful optical telescopes. More recent developments, like satellites, might be visible out to 60ly. It is basically a signal travel speed issue. So, the paper doesn't mention this, but if -- and only if -- they're looking for pyramids, we're visible to about 0.1% of the galaxy.

bemusedthrow75 3y ago
> So the pyramids are visible out to 3000 light years away if the aliens have extremely powerful optical telescopes. Is such a telescope (resolving power etc.) actually possible? At the level of basic physics, could anyone build it, hypothetically? I don't know, because I am an idiot who has spent 30 years building websites of various complexity and pretending that is advanced knowledge.
- boomboomsubban 3y ago
  It seems to involve building a telescope with a diameter of several million kilometers. As a reminder, the circumference of the earth is about 40,000km. So several hundred times bigger than the earth. It's hard to imagine, but the baseline mentioned is being able to utilize all the energy of their star.
  - jandrese 3y ago
    Anybody who starts off their paper with mentions of the Kardashev scale is already pretty far out there. It has never been clear to me if even a Level 1 civilization is practical, there could well be physical (as in physics based, like thermodynamics) limits that prevent you from reaching that point. And the scale goes dramatically up from there. Level 2 is building Dyson Spheres. It always felt like the whole thing was made by someone who didn't really have a good grasp of scale. Maybe it's a failure of imagination on my part, but I tend to think that projects on scales like that are just too impractical for real life. It's like if you decided to make up a scale for land speed records, and made type 1 100,000 kph, level 2 100,000,000 kph, and level 3 100,000,000,000 kph.
  - Kye 3y ago
    I like to think a sufficiently advanced civilization can stack gravity lenses to get a better view the way camera lenses stack multiple bits of glass and plastic to clear up different kinds of problem.
  - kshacker 3y ago
    Not only they need that powerful a telescope, they need to be focused on exactly where the pyramids are/were because that that zoom, they could be scanning a whole lot of nothingness.
  - intotheabyss 3y ago
    More likely they'd use their star for magnification by placing telescopes at the right focal point.
  - ufmace 3y ago
    So it might be possible for a sufficiently advanced species to build such a thing. But would they choose to? The real question for these things is, if you are capable of building such a thing, what other things are you capable of building much simpler and cheaper that can do the job better?
  - whoopsie 3y ago
    The only industry capitalized to support that is porn. So if it does happen, this is very bad news for us.
- intelVISA 3y ago
  > an idiot who has spent 30 years building websites of various complexity and pretending that is advanced knowledge Tbf web has an unmatched pay to work ratio for the avg. developer, I wouldn't call that idiotic by any stretch.
  - bemusedthrow75 3y ago
    Oh I didn't say I was well-paid doing it :-/
- tzs 3y ago
  Yes, it is possible. Briefly, you use your solar system's star as a gravitational lens. There are currently a couple proposals working their way through the system to do that here in our solar system. It doesn't require technology much beyond what we already have, nor is it much more expensive than other unmanned deep space missions. We wouldn't be able to see pyramid sized objects on alien planets that way because the Sun is only about 1.4 million km diameter, and from other comments it would take a few million km. But for aliens with a bigger star? No problem. Here's a PBS Space Time episode that talks about the proposals for building a Sun based gravity lens telescope [1]. [1] https://www.youtube.com/watch?v=4d0EGIt1SPc https://www.youtube.com/watch?v=4d0EGIt1SPc
  - sph 3y ago
    It is possible in theory. Until we build one, I wouldn't be so sure it's as effective as claimed to be.
rybosworld 3y ago
It's fun to imagine the possibility of apparent FTL in these conversations. Apparent FTL is at least theoretically possible under our current understanding (though a unification of quantum and general physics may change this).
- shmageggy 3y ago
  > Apparent FTL is at least theoretically possible under our current understanding That's news to me. Source?
  - amelius 3y ago
    Hmm, they say "apparent FTL", not "actual FTL", so it sounds like some form of cheating is involved.
masklinn 3y ago
> So the pyramids are visible out to 3000 light years away Surely it’s 4? .5? The great pyramids are from 2500 BC.
steelframe 3y ago
Wouldn't advanced civilizations at least be doing what we've been doing recently, looking at the transit spectroscopy for distant planets to determine whether we think they can support carbon-based life? Likewise, couldn't they detect changes in the mixture of gases on Earth and deduce that these changes would most likely occur in the presence of evolving life? If we posit that evolution typically leads to intelligence and intelligence leads to civilization, then extraterrestrial intelligence would have deduced that we were going to be coming along at some point. Maybe they could even deduce when that civilization-building life was going to spring up, perhaps within about a ~1M-year window, depending on what information they have and what they can reliably deduce from that information. So in a way we are already "known." The new information that you can glean from the pyramids is that we've just now hit the inflection point of civilization. Maybe now they're watching to see if we manage to make it past the Great Filter. Or they've already launched their relativistic missiles to snuff us out before we can possibly launch our relativistic missiles at them -- if you're inclined to presume the cosmic prisoner's dilemma motivates being the first to launch.
- gmuslera 3y ago
  Having free oxygen in the atmosphere (I don’t know, 500 M-year?) would already had put us as target for oxygen breathing advanced civilizations in a long enough radius. If they could be a realistic threat capable of wiping us, they should had been here even before mankind evolved. Maybe the great filter is the great promotion, acquiring a knowledge/technology powerful enough to not need to go to other solar systems or expand a lot. But as we are not yet there, we expect invasion fleets.
  - steelframe 3y ago
    > If they could be a realistic threat capable of wiping us, they should had been here even before mankind evolved. One of my favorite sci-fi themes about that is that we've already been hit once, about 66 million years ago.
- nicklecompte 3y ago
  > If we posit that evolution typically leads to intelligence and intelligence leads to civilization, then extraterrestrial intelligence would have deduced that we were going to be coming along at some point. I see two big issues with this: 1) "evolution typically leads to intelligence" is only plausible after the evolution of multicellular life. I don't think there's any reason to suppose "evolution typically leads to multicellular life." Perhaps these aliens are used to a galaxy where 95% of habitable planets are full of primordial soup, where primitive multicellular forms struggle to find a niche. In particular, if most planets are less geologically active than earth, and most solar systems have less asteroids than ours, then perhaps most habitable planets have less extinction events, so there wouldn't be any ecological disruption to spur evolution. 2) "intelligence leads to civilization" is almost certainly false. Orcas have near-human intelligence, including culture and symbolic communication - in fact they might be "smarter" than humans, we don't really know enough about intelligence to answer that. But it will take a bizarre fluke of evolution for them to develop technological civilization, for the simple reason that they don't have hands and there's no selective pressure for them to evolve "proto-hands" - they need the flippers to be good flippers. This is in contrast to primates: we didn't evolve hands to build tools, we evolved hands to climb trees and grab fruits/nuts. It seems far more likely to me that intelligence tends towards super smart crows and dolphins: the physiological capability of building highly advanced tools is orthogonal to intelligence and does not seem inevitable. I'm not saying you're wrong. But my understanding of the almost-science is that the aliens would be wasting a lot of tachyon missiles if they fired at every planet with evidence of photosynthesis / fermentation / etc.

bemusedthrow75 3y ago

> So the pyramids are visible out to 3000 light years away if the aliens have extremely powerful optical telescopes. Is such a telescope (resolving power etc.) actually possible? At the level of basic physics, could anyone build it, hypothetically? I don't know, because I am an idiot who has spent 30 years building websites of various complexity and pretending that is advanced knowledge.

boomboomsubban 3y ago
It seems to involve building a telescope with a diameter of several million kilometers. As a reminder, the circumference of the earth is about 40,000km. So several hundred times bigger than the earth. It's hard to imagine, but the baseline mentioned is being able to utilize all the energy of their star.
- jandrese 3y ago
  Anybody who starts off their paper with mentions of the Kardashev scale is already pretty far out there. It has never been clear to me if even a Level 1 civilization is practical, there could well be physical (as in physics based, like thermodynamics) limits that prevent you from reaching that point. And the scale goes dramatically up from there. Level 2 is building Dyson Spheres. It always felt like the whole thing was made by someone who didn't really have a good grasp of scale. Maybe it's a failure of imagination on my part, but I tend to think that projects on scales like that are just too impractical for real life. It's like if you decided to make up a scale for land speed records, and made type 1 100,000 kph, level 2 100,000,000 kph, and level 3 100,000,000,000 kph.
- Kye 3y ago
  I like to think a sufficiently advanced civilization can stack gravity lenses to get a better view the way camera lenses stack multiple bits of glass and plastic to clear up different kinds of problem.
- kshacker 3y ago
  Not only they need that powerful a telescope, they need to be focused on exactly where the pyramids are/were because that that zoom, they could be scanning a whole lot of nothingness.
- intotheabyss 3y ago
  More likely they'd use their star for magnification by placing telescopes at the right focal point.
- ufmace 3y ago
  So it might be possible for a sufficiently advanced species to build such a thing. But would they choose to? The real question for these things is, if you are capable of building such a thing, what other things are you capable of building much simpler and cheaper that can do the job better?
- whoopsie 3y ago
  The only industry capitalized to support that is porn. So if it does happen, this is very bad news for us.
intelVISA 3y ago
> an idiot who has spent 30 years building websites of various complexity and pretending that is advanced knowledge Tbf web has an unmatched pay to work ratio for the avg. developer, I wouldn't call that idiotic by any stretch.
- bemusedthrow75 3y ago
  Oh I didn't say I was well-paid doing it :-/
tzs 3y ago
Yes, it is possible. Briefly, you use your solar system's star as a gravitational lens. There are currently a couple proposals working their way through the system to do that here in our solar system. It doesn't require technology much beyond what we already have, nor is it much more expensive than other unmanned deep space missions. We wouldn't be able to see pyramid sized objects on alien planets that way because the Sun is only about 1.4 million km diameter, and from other comments it would take a few million km. But for aliens with a bigger star? No problem. Here's a PBS Space Time episode that talks about the proposals for building a Sun based gravity lens telescope [1]. [1] https://www.youtube.com/watch?v=4d0EGIt1SPc https://www.youtube.com/watch?v=4d0EGIt1SPc
- sph 3y ago
  It is possible in theory. Until we build one, I wouldn't be so sure it's as effective as claimed to be.

rybosworld 3y ago

It's fun to imagine the possibility of apparent FTL in these conversations. Apparent FTL is at least theoretically possible under our current understanding (though a unification of quantum and general physics may change this).

shmageggy 3y ago
> Apparent FTL is at least theoretically possible under our current understanding That's news to me. Source?
- amelius 3y ago
  Hmm, they say "apparent FTL", not "actual FTL", so it sounds like some form of cheating is involved.

masklinn 3y ago

> So the pyramids are visible out to 3000 light years away Surely it’s 4? .5? The great pyramids are from 2500 BC.

steelframe 3y ago

Wouldn't advanced civilizations at least be doing what we've been doing recently, looking at the transit spectroscopy for distant planets to determine whether we think they can support carbon-based life? Likewise, couldn't they detect changes in the mixture of gases on Earth and deduce that these changes would most likely occur in the presence of evolving life? If we posit that evolution typically leads to intelligence and intelligence leads to civilization, then extraterrestrial intelligence would have deduced that we were going to be coming along at some point. Maybe they could even deduce when that civilization-building life was going to spring up, perhaps within about a ~1M-year window, depending on what information they have and what they can reliably deduce from that information. So in a way we are already "known." The new information that you can glean from the pyramids is that we've just now hit the inflection point of civilization. Maybe now they're watching to see if we manage to make it past the Great Filter. Or they've already launched their relativistic missiles to snuff us out before we can possibly launch our relativistic missiles at them -- if you're inclined to presume the cosmic prisoner's dilemma motivates being the first to launch.

gmuslera 3y ago
Having free oxygen in the atmosphere (I don’t know, 500 M-year?) would already had put us as target for oxygen breathing advanced civilizations in a long enough radius. If they could be a realistic threat capable of wiping us, they should had been here even before mankind evolved. Maybe the great filter is the great promotion, acquiring a knowledge/technology powerful enough to not need to go to other solar systems or expand a lot. But as we are not yet there, we expect invasion fleets.
- steelframe 3y ago
  > If they could be a realistic threat capable of wiping us, they should had been here even before mankind evolved. One of my favorite sci-fi themes about that is that we've already been hit once, about 66 million years ago.
nicklecompte 3y ago
> If we posit that evolution typically leads to intelligence and intelligence leads to civilization, then extraterrestrial intelligence would have deduced that we were going to be coming along at some point. I see two big issues with this: 1) "evolution typically leads to intelligence" is only plausible after the evolution of multicellular life. I don't think there's any reason to suppose "evolution typically leads to multicellular life." Perhaps these aliens are used to a galaxy where 95% of habitable planets are full of primordial soup, where primitive multicellular forms struggle to find a niche. In particular, if most planets are less geologically active than earth, and most solar systems have less asteroids than ours, then perhaps most habitable planets have less extinction events, so there wouldn't be any ecological disruption to spur evolution. 2) "intelligence leads to civilization" is almost certainly false. Orcas have near-human intelligence, including culture and symbolic communication - in fact they might be "smarter" than humans, we don't really know enough about intelligence to answer that. But it will take a bizarre fluke of evolution for them to develop technological civilization, for the simple reason that they don't have hands and there's no selective pressure for them to evolve "proto-hands" - they need the flippers to be good flippers. This is in contrast to primates: we didn't evolve hands to build tools, we evolved hands to climb trees and grab fruits/nuts. It seems far more likely to me that intelligence tends towards super smart crows and dolphins: the physiological capability of building highly advanced tools is orthogonal to intelligence and does not seem inevitable. I'm not saying you're wrong. But my understanding of the almost-science is that the aliens would be wasting a lot of tachyon missiles if they fired at every planet with evidence of photosynthesis / fermentation / etc.