Oh yeah. Orcas. The other highly intelligent, highly social apex predators that haven't graduated from sexual violence for domination and torturing lesser creatures for fun.
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.
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.
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.
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.
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?
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.
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].
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.
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.
> 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.
It might take a few years, or hundreds, or thousands to finally receive a tentative "hello?" transmission from them, however. I struggle to even imagine how Earth's civilizations would react to such a "phone call."
by the time they are able to discern features like buildings on the surface, they should have already been able to see what type of atmosphere Earth has. they should have already been able to detect radio signals from Earth.
It's neat that it focuses on visible-light observations through a telescope, but I wonder what else is visible at long distances. Would spectroscopy reveal other evidence of our existence? Besides the change in atmospheric co2 levels (which could be explained by natural ebbs and flows caused by, I don't know, volcanoes?), would they see an increase in our use of refrigerants in the late 1900s? Would the effects of nuclear detonations be detectable at all, even in principle? What about things like the use of sodium lamps, and then the switch to more LED lighting?
Tsar Bomba was detonated in October 1961. That means that for any civilization to have seen it, that civilization must be within 63 light years of Earth. In addition, unlike the Pyramids, Tsar Bomba was a momentary flash, so if a civilization within that distance started looking today, they wouldn't see it. They probably wouldn't even see evidence of it, since here on Earth we can detect only traces that it specifically happened.
What the paper talks about is constantly visible evidence of human life. Civilizations up to 3000 light-years away can see evidence of the Pyramids because they were built 3000 years ago and have been visible from space ever since.
This paper is very silly. It considers only trying to resolve features with a colossal optical telescope instead of the far easier method of monitoring the chemistry of the atmosphere via spectral absorption lines as it passes in front of the host star to watch for unnaturally rapid changes in carbon dioxide and other chemicals.
Let's see: Our galaxy is what, rough ballpark 100,000 light years (LY) in diameter. Soooo, to have a reasonably large collection of aliens to detect us, ask that they be ~50,000 LY or so away. Soooo, by now all they could get from us would be from what we were doing ~50,000 years ago. But we've been radiating from our civilization only in the last ~200 years.
Net, the aliens would have to wait ~50,000 years to receive anything very interesting from us. Sooo, have they detected us yet? Likely not. Instead they will have to wait another ~50,000 years.
And even if alien ET (extra terrestrial) has found how to travel and signal faster than light, OUR signals, what WE have sent, will still travel only at the speed of light.
The answer is yes. Simply because the question is flawed.
The premise of the question is advanced alien civilizations exist.
It asks are we visible to them. We don't have a definition of what advanced here, so for any answer that's no yes, let's just assume they could get more advanced.
So the question is just: are we visible? (Assuming infinity advancement and that there are alien civilizations). Yes we are visible.
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[ 0.19 ms ] story [ 111 ms ] threadIf we are being observed by Aliens, I hope they focus on animals, specifically Elephants, Dolphins, Orca and Penguins.
Who actively destroys their environ? Humans. these animals master their environment without destruction. Humans destroy.
You are fun at BDSM parties.
They are highly capable, intelligent and enjoy violence for the sake of it.
Give them limbs and opposable thumbs and they would be just like us.
There's absolutely no reason to project any kind of higher, more connected, more honest natural wisdom onto them.
(i mean that, im not being rude)
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.
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.
It's hard to imagine, but the baseline mentioned is being able to utilize all the energy of their star.
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.
Tbf web has an unmatched pay to work ratio for the avg. developer, I wouldn't call that idiotic by any stretch.
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
Apparent FTL is at least theoretically possible under our current understanding (though a unification of quantum and general physics may change this).
That's news to me. Source?
Surely it’s 4? .5? The great pyramids are from 2500 BC.
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.
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.
One of my favorite sci-fi themes about that is that we've already been hit once, about 66 million years ago.
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.
It might take a few years, or hundreds, or thousands to finally receive a tentative "hello?" transmission from them, however. I struggle to even imagine how Earth's civilizations would react to such a "phone call."
Somewhat more seriously, I have my doubts we would even pick up or recognize the hello today.
I learnt about this about a decade ago and was a nice read.
https://www.youtube.com/watch?v=Ttwl_zH_DZ8
some other great related episodes (but really all are fantastic)
https://www.youtube.com/watch?v=uTrFAY3LUNw
https://www.youtube.com/watch?v=cJONS7sqi0o
https://www.youtube.com/watch?v=uhJ9lJPt09k
TRT 17 mins. Actual content 13 mins with the remaining 4 mins about Patreon/subscription/blah. That's just gross.
not totally kidding: https://earthobservatory.nasa.gov/images/144386/toward-mappi...
But life on Earth has a strong tendency into aggregating into complex organisms, so we can expect that one step to happen everywhere.
https://en.wikipedia.org/wiki/Tsar_Bomba#Analysis
What the paper talks about is constantly visible evidence of human life. Civilizations up to 3000 light-years away can see evidence of the Pyramids because they were built 3000 years ago and have been visible from space ever since.
Net, the aliens would have to wait ~50,000 years to receive anything very interesting from us. Sooo, have they detected us yet? Likely not. Instead they will have to wait another ~50,000 years.
And even if alien ET (extra terrestrial) has found how to travel and signal faster than light, OUR signals, what WE have sent, will still travel only at the speed of light.
The premise of the question is advanced alien civilizations exist.
It asks are we visible to them. We don't have a definition of what advanced here, so for any answer that's no yes, let's just assume they could get more advanced.
So the question is just: are we visible? (Assuming infinity advancement and that there are alien civilizations). Yes we are visible.