First Ever Image of a Multi-Planet System Around a Sun-Like Star Captured by ESO(eso.org)
eso.org
First Ever Image of a Multi-Planet System Around a Sun-Like Star Captured by ESO
https://www.eso.org/public/news/eso2011/?lang
179 comments
The pictures are much better quality than I expected! I thought I'd be lucky to see a couple specks. These are reminiscent of (and a bit better than) looking at Jupiter through a small refractor.
Not to mention these are gas giants at a relatively nearby star (300 lightyears away) and we consider the universe is something shy of 100 billion lightyears in diameter. We're not even scratching the surface!
The more unlikely it gets that we would be the only intelligent life, the more dire our future outlook, due to the lack of signs of intelligent civilization in the stars. If they must have existed, then there must also be a reason they don't anymore.
> the lack of signs of intelligent civilization in the stars
And what would such sings look like? The only conceivable sign that we could observe with our current technology is Dyson spheres. It's however entirely reasonable that intelligent civilizations can advance to quite highly technological levels and not develop Dyson spheres.
If a civilization like ours were to inhabit the nearest star system, Proxima Centauri, and zip happily in rockets from one planet to another (of which there are at least 2 confirmed), and beam radio messages back and forth among themselves, would we be able to tell?
And what would such sings look like? The only conceivable sign that we could observe with our current technology is Dyson spheres. It's however entirely reasonable that intelligent civilizations can advance to quite highly technological levels and not develop Dyson spheres.
If a civilization like ours were to inhabit the nearest star system, Proxima Centauri, and zip happily in rockets from one planet to another (of which there are at least 2 confirmed), and beam radio messages back and forth among themselves, would we be able to tell?
Not to mention that there may be alternatives to Dyson swarms that anyone capable of building one learns about on the way to gaining that capability.
I'll start listening to people telling me about missing signs after we have a unified theory of physics that includes an interpretation of QM, quantum gravity with proper explanations for galactic rotation and inflation among other things.
I'll start listening to people telling me about missing signs after we have a unified theory of physics that includes an interpretation of QM, quantum gravity with proper explanations for galactic rotation and inflation among other things.
There are other, albeit more far fetched, ideas about the situation.
One I find interesting is that we are like a chick pecking away at our egg shell. As we get closer to being multi-planetary do we get to be more or less warlike? Do we settle on one ruling class and everyone else in bonds, or do we settle on a shared bounty? Do we destroy the world that birthed us, or do we come to grips with our own needs and develop what we need to live in perpetuity on the world we started on?
On a much larger scale it doesn't seem all that much different than the growth of a person from child, to teen, to young adult, and adult. And in those stages of growth the perception of the world and one's place in it changes. Some learn self restraint, others do not, Etc. Even before young people start to drive they get to point where doing stupid things can kill them.
The theory I find interesting is that civilizations are out there watching and the history is that some civilizations "grow up" and survive, and others don't. Some do something stupid in their "teen years" and kill themselves off, some develop a personality that results in them doing something that kills them. Some make it through that and become adults with a reasonable understanding and nominal "acceptance" of the things one has to do to stay alive and be civil.
Maybe when we're "old enough" as a civilization, and we certainly will have enough science to understand that other civilizations could exist and how. They will introduce themselves.
One I find interesting is that we are like a chick pecking away at our egg shell. As we get closer to being multi-planetary do we get to be more or less warlike? Do we settle on one ruling class and everyone else in bonds, or do we settle on a shared bounty? Do we destroy the world that birthed us, or do we come to grips with our own needs and develop what we need to live in perpetuity on the world we started on?
On a much larger scale it doesn't seem all that much different than the growth of a person from child, to teen, to young adult, and adult. And in those stages of growth the perception of the world and one's place in it changes. Some learn self restraint, others do not, Etc. Even before young people start to drive they get to point where doing stupid things can kill them.
The theory I find interesting is that civilizations are out there watching and the history is that some civilizations "grow up" and survive, and others don't. Some do something stupid in their "teen years" and kill themselves off, some develop a personality that results in them doing something that kills them. Some make it through that and become adults with a reasonable understanding and nominal "acceptance" of the things one has to do to stay alive and be civil.
Maybe when we're "old enough" as a civilization, and we certainly will have enough science to understand that other civilizations could exist and how. They will introduce themselves.
It can simply be that civilisations, no matter how intelligent, do not send out any signals that are strong enough for us to detect from our distance.
Its not signals. They should already be here if interstellar colonization is at all possible.
I don't think there is sufficient evidence to say that an automated probe has not already visited our solar system. Let's consider two probe types Von Neumann and Bracewell
Von Neumann: 1) They arrived too early for us to have a chance of detecting them and they left little trace 2) One or more have arrived recently but they are discrete e.g. no active propulsion, passive sensors, tight beam communication, they only harvest a small amount of material for self-replication etc. 3) We just aren't looking hard enough, space is big and we have limited resources devoted to this pursuit 4) We've observed the activity of a probe but we mistook it for an anomaly or a natural occurrence
Bracewell: 1) Non-self replicating and arrived and left too early 2) Present but not fully autonomous and awaiting confirmation to begin contact (could be a long time waiting depending on distance from home) 3) Present, fully autonomous but we haven't met the criteria to begin contact 4) Present, fully autonomous, has attempted to contact us but we lack the ability to detect and understand their method of communication 5) Present, fully autonomous, has successfully contacted us but whoever was in contact has successfully convinced the probe to not make itself more widely known and has managed to keep their own communication with it a secret (probably the most unlikely scenario but still possible if the probe has protocols for dealing with local geopolitics)
If we're talking about colonization by the alien species itself there are still further explanations for silence:
1) All civilizations capable of reaching us have some equivalent of the "Prime Directive" where they do not forcibly colonize or contact primitive civilizations 2) No civilizations attempt to colonize the entire galaxy, perhaps they all focus on fully utilizing each solar system as they need it, maybe they eventually run out of needs that require expansion. The human population is trending towards replacement level birthrate within the next 100 years, if that is a common trend for all intelligent life then their population may simply stop expanding at some point and after a limited number of systems are colonized they may not have enough population to support further expansion. Maybe birthrates actually trend to 0 and lifespan approaches immortality. 3) Maybe colonizing planets is a dumb idea. Gravity wells are hard to get out of so once your civilization moves to space maybe it just stays in space. We are proposing generation ships as a main method of colonization but if the ship is good enough to live on for generations then why disembark? Why not just continue to live in space habitats and travel the galaxy continuously? Planets are dangerous and unpredictable with uncontrolled weather, volcanism, asteroid impacts, solar flares, etc. If you build a synthetic world you don't need to worry about that. 4) There might be other alternatives, upload to VR, conversion to another form of matter, time travel, alternate universes. These are pretty unlikely but so is the probability that we are the only life to have emerged in such a vast galaxy.
Von Neumann: 1) They arrived too early for us to have a chance of detecting them and they left little trace 2) One or more have arrived recently but they are discrete e.g. no active propulsion, passive sensors, tight beam communication, they only harvest a small amount of material for self-replication etc. 3) We just aren't looking hard enough, space is big and we have limited resources devoted to this pursuit 4) We've observed the activity of a probe but we mistook it for an anomaly or a natural occurrence
Bracewell: 1) Non-self replicating and arrived and left too early 2) Present but not fully autonomous and awaiting confirmation to begin contact (could be a long time waiting depending on distance from home) 3) Present, fully autonomous but we haven't met the criteria to begin contact 4) Present, fully autonomous, has attempted to contact us but we lack the ability to detect and understand their method of communication 5) Present, fully autonomous, has successfully contacted us but whoever was in contact has successfully convinced the probe to not make itself more widely known and has managed to keep their own communication with it a secret (probably the most unlikely scenario but still possible if the probe has protocols for dealing with local geopolitics)
If we're talking about colonization by the alien species itself there are still further explanations for silence:
1) All civilizations capable of reaching us have some equivalent of the "Prime Directive" where they do not forcibly colonize or contact primitive civilizations 2) No civilizations attempt to colonize the entire galaxy, perhaps they all focus on fully utilizing each solar system as they need it, maybe they eventually run out of needs that require expansion. The human population is trending towards replacement level birthrate within the next 100 years, if that is a common trend for all intelligent life then their population may simply stop expanding at some point and after a limited number of systems are colonized they may not have enough population to support further expansion. Maybe birthrates actually trend to 0 and lifespan approaches immortality. 3) Maybe colonizing planets is a dumb idea. Gravity wells are hard to get out of so once your civilization moves to space maybe it just stays in space. We are proposing generation ships as a main method of colonization but if the ship is good enough to live on for generations then why disembark? Why not just continue to live in space habitats and travel the galaxy continuously? Planets are dangerous and unpredictable with uncontrolled weather, volcanism, asteroid impacts, solar flares, etc. If you build a synthetic world you don't need to worry about that. 4) There might be other alternatives, upload to VR, conversion to another form of matter, time travel, alternate universes. These are pretty unlikely but so is the probability that we are the only life to have emerged in such a vast galaxy.
Couldn't they just be at a similar evolutionary level to us, looking at the first photo of our solar system taken from theirs?
I think the earth is considered relatively young and so are humans compared to the universe so there should be others. Hence the Fermi paradox.
Nah we are just out in the sticks.
There's also the Dark Forest theory which suggests any space faring civilization which broadcasts signals too loudly is "quickly" eliminated/threatened by a more advanced civilization. All that remain are the civilizations smart enough to remain silent.
I think simply based on size, you would be crazy to not think there is life out there.
I think that if we were truly the only ones out here that would be the best evidence for God..
I think that if we were truly the only ones out here that would be the best evidence for God..
Question: What do you consider ‘intelligence’?
I mean, we don’t need to look outside our own planet to find traits of what I consider intelligent behavior in other species.
I have a feeling that if we find an alien species it wont be intelligent, simply because we won’t define it as such. They might even have technology we couldn’t even begin to understand, but at the same time they will probably fail at exhibiting something we consider basic. And worse, they will have no way of being taught.
Aside: I suggest in the future—if you want to avoid pedantic comment like these—that you reword your last sentence to include intelligent life on earth, e.g. “The notion that earth is the only planet to harbor intelligent life...”
I mean, we don’t need to look outside our own planet to find traits of what I consider intelligent behavior in other species.
I have a feeling that if we find an alien species it wont be intelligent, simply because we won’t define it as such. They might even have technology we couldn’t even begin to understand, but at the same time they will probably fail at exhibiting something we consider basic. And worse, they will have no way of being taught.
Aside: I suggest in the future—if you want to avoid pedantic comment like these—that you reword your last sentence to include intelligent life on earth, e.g. “The notion that earth is the only planet to harbor intelligent life...”
Its a fair question. My take on it is more toward the introspection/self-analytical side of the argument than the tool-using/self-awareness side. Though both are clearly "intelligent" in the dictionary definition.
In casual conversation however, per Gretchen McCulloch's book "Because Internet"[1], I tend to stick with phrases that are most accessible rather than those that are most precise.
My experience is that being overly precise in my speech can be off-putting to people. Enough so, that when I have encouraged feedback, both positive and negative, on my communication skills it came up more than once as "making you seem like you are showing off how much you know about something and making others feel dumb."
[1] Really a great read, my daughter got it for me for my birthday and I thoroughly enjoyed it.
In casual conversation however, per Gretchen McCulloch's book "Because Internet"[1], I tend to stick with phrases that are most accessible rather than those that are most precise.
My experience is that being overly precise in my speech can be off-putting to people. Enough so, that when I have encouraged feedback, both positive and negative, on my communication skills it came up more than once as "making you seem like you are showing off how much you know about something and making others feel dumb."
[1] Really a great read, my daughter got it for me for my birthday and I thoroughly enjoyed it.
> My experience is that being overly precise in my speech can be off-putting to people. Enough so, that when I have encouraged feedback, both positive and negative, on my communication skills it came up more than once as "making you seem like you are showing off how much you know about something and making others feel dumb."
File this under 'know your audience'. On HN (and other nerdy and text-based communication) precision is often much more welcome than in oral communication in real life. Even with the same sort of people.
File this under 'know your audience'. On HN (and other nerdy and text-based communication) precision is often much more welcome than in oral communication in real life. Even with the same sort of people.
We could use an utilitarian definition of "intelligent life" that would mean something like "able to communicate or directly interact with us". I wonder if ant colonies or fungi consider us intelligent life.
A relativistic definition of intelligence: I think it would be hard to do, e.g. your example would make dogs one of the most intelligent species on Earth, relative to humans, much smarter then chimpanzees. To be frank I find the whole concept of intelligence to be more problematic then its worth.
That said, if we are ever able to establish communication with a species other then our own that evolved elsewhere in the galaxy, intelligence might at that point become an outdated concept.
That said, if we are ever able to establish communication with a species other then our own that evolved elsewhere in the galaxy, intelligence might at that point become an outdated concept.
Fair enough. I do think that finding evidence of extra-terrestrial life would be amazing enough. If we could then later explore how life outside our own planet behaves, I am in no doubt that our minds will be blown. And if we find a way to communicate with one of these species... perhaps by that time any philosophical speculation on what intelligence is will be rendered obsolete.
making you seem like you are showing off how much you know about something and making others feel dumb
I wish we could get past this (finding intelligence offensive while finding physical strength appealing) as a species. But until then it's good advice.
It's also a bit of a double bind: if you're not precise enough, someone will be offended by your ambiguity. If you're too precise, someone will be offended by your precision. It limits the rate at which experts can convey knowledge, which can be problematic at work as teams are limited to the pace of whoever is most offended.
I wish we could get past this (finding intelligence offensive while finding physical strength appealing) as a species. But until then it's good advice.
It's also a bit of a double bind: if you're not precise enough, someone will be offended by your ambiguity. If you're too precise, someone will be offended by your precision. It limits the rate at which experts can convey knowledge, which can be problematic at work as teams are limited to the pace of whoever is most offended.
When communicating face-to-face, you typically have real time feedback. So you can afford to be more potentially ambiguous, because you monitor for misunderstandings, and clear them up as they arise.
If you want to go all mathematical, that's similar to just sticking a checksum on tcp packets and resending vs the lengths that CD-ROMs go to correct errors.
Or to bring another analogy, compare an interactive proof (https://en.wikipedia.org/wiki/Interactive_proof_system) with a more conventional formal proof.
As an aside, people do admire intelligence in real life perhaps more so than physical strength, but a minimum of social acumen goes a long way.
If you want to go all mathematical, that's similar to just sticking a checksum on tcp packets and resending vs the lengths that CD-ROMs go to correct errors.
Or to bring another analogy, compare an interactive proof (https://en.wikipedia.org/wiki/Interactive_proof_system) with a more conventional formal proof.
As an aside, people do admire intelligence in real life perhaps more so than physical strength, but a minimum of social acumen goes a long way.
> Aside: I suggest in the future—if you want to avoid pedantic comment like these—that you reword your last sentence to include intelligent life on earth, e.g. “The notion that earth is the only planet to harbor intelligent life...”
Pedantic note on "I suggest in the future": you didn't suggest it in the future. If you want to avoid pedantic comments like these, I suggest you assume good faith and stop being an ass, or, take an English class. Also, Earth, in your usage, is capitalized.
Pedantic note on "I suggest in the future": you didn't suggest it in the future. If you want to avoid pedantic comments like these, I suggest you assume good faith and stop being an ass, or, take an English class. Also, Earth, in your usage, is capitalized.
Sorry, but there is a fundamental difference. My original comment is about something that is either factually wrong (humans are not the only intelligent species on Earth), or problematic on a philosophical level (intelligent is not a useful concept). You point your criticism on my tone, or English ability, which is superficial.
Also can people please stop attacking each others english ability, it is a really bad abelist thing to do. We don’t all come from an educated background, we don’t all have english as our native language. Please try to empathize with those of us that have a harder time using english then you.
Also can people please stop attacking each others english ability, it is a really bad abelist thing to do. We don’t all come from an educated background, we don’t all have english as our native language. Please try to empathize with those of us that have a harder time using english then you.
I've gone back and forth on this. As a kid I read plenty of older SF where humanocentric biases were laughably prevalent. Aliens were amazed at our incredibly advanced mathematics because we used the clearly superior Base 10. Or aliens adopted English because it was so much more sophisticated than their own languages. Aliens all being basically humanoid was explained because it is clearly the only body form suitable for developing advanced technology.
In a kind of allergic reaction to this sort of thing, there was a movement in SF that aliens would be likely to be so different from us that we would be unlikely to even recognise them as intelligent. Stanislaw Lem's Solaris is a well known example, and the Pandora sequence by Frank Herbert was interesting. I never quite bought it though, and Nemesis by Isaac Asimov seemed to me to be a particularly lazy example that pretty much put me off the whole idea. (I'm a fan of Asimov, but this one didn't work for me).
On the one had we can look at life on earth to see the huge variety of biological forms that are possible even just on our own planet, with fundamentally the same core biology throughout. On the other hand, any life in our universe is going to be constrained by the same basic principles of chemistry, physics and emergent constraints such as thermodynamics, information theory and natural selection. The problem with most of the efforts at 'truly alien' aliens is they emphasise their alien-ness by showing them violate such principles to show how 'we don't know as much as we think we do'.
I don't buy it. Thermodynamics, natural selection, information theory, etc - we know these things. They're real constraints that any life, anywhere must contend with and they constrain what can or can't work within comprehensible limits. I'm not at all saying that genuine alien life can't be surprising, that we won't learn anything new from it. We learn new stuff form like here on earth all the time. I'm just saying we actually know a pretty decent amount about how the universe works at a basic level and this will give us a decent chance at figuring this stuff out.
That's where I am this this now, but it's a complex issue. I really need to watch Arrival though.
In a kind of allergic reaction to this sort of thing, there was a movement in SF that aliens would be likely to be so different from us that we would be unlikely to even recognise them as intelligent. Stanislaw Lem's Solaris is a well known example, and the Pandora sequence by Frank Herbert was interesting. I never quite bought it though, and Nemesis by Isaac Asimov seemed to me to be a particularly lazy example that pretty much put me off the whole idea. (I'm a fan of Asimov, but this one didn't work for me).
On the one had we can look at life on earth to see the huge variety of biological forms that are possible even just on our own planet, with fundamentally the same core biology throughout. On the other hand, any life in our universe is going to be constrained by the same basic principles of chemistry, physics and emergent constraints such as thermodynamics, information theory and natural selection. The problem with most of the efforts at 'truly alien' aliens is they emphasise their alien-ness by showing them violate such principles to show how 'we don't know as much as we think we do'.
I don't buy it. Thermodynamics, natural selection, information theory, etc - we know these things. They're real constraints that any life, anywhere must contend with and they constrain what can or can't work within comprehensible limits. I'm not at all saying that genuine alien life can't be surprising, that we won't learn anything new from it. We learn new stuff form like here on earth all the time. I'm just saying we actually know a pretty decent amount about how the universe works at a basic level and this will give us a decent chance at figuring this stuff out.
That's where I am this this now, but it's a complex issue. I really need to watch Arrival though.
if we find an alien species they would indeed be equal or less intelligent. a more intelligent species would find us first.
Sorry, but you are missing the point. Intelligence is an incredibly human-centric concept. Everything we consider “intelligent” behavior, or “intelligent” traits is relative to humans. A good example is how we consider Chimpanzees a “remarkably intelligent species” because they use tools like we humans do. However an ant colony is not considered intelligent even though it has large scale agriculture, social hierarchy and communication techniques we don’t fully understand. And let alone fungal networks which behavior is so alien to us that it could be exhibiting behavior very intelligent to them, but our understanding of fungal life is so limited that we can’t even begin to see it as ‘intelligent’.
If we do come across extra-terrestrial life (more likely through our telescopes, rather then by paying a visit) it will be even more alien to us then our mushroom cousins. It will have evolved in a planet vastly different from us, it might communicate in a way we can’t even think of. Our technology will have more in common with the ant colonies then with the alien technology.
If we do come across extra-terrestrial life and are able to marvel at their intelligence, then I think it will have more to do with our ability to understand things out of our scope, rather then some absolute and arbitrary metric of intelligence.
If we do come across extra-terrestrial life (more likely through our telescopes, rather then by paying a visit) it will be even more alien to us then our mushroom cousins. It will have evolved in a planet vastly different from us, it might communicate in a way we can’t even think of. Our technology will have more in common with the ant colonies then with the alien technology.
If we do come across extra-terrestrial life and are able to marvel at their intelligence, then I think it will have more to do with our ability to understand things out of our scope, rather then some absolute and arbitrary metric of intelligence.
> However an ant colony is not considered intelligent even though it has large scale agriculture, social hierarchy and communication techniques we don’t fully understand.
Actually, ants are frequently deemed smart and intelligent. Such suppositions are common.
Actually, ants are frequently deemed smart and intelligent. Such suppositions are common.
Indeed, and there are also people actively investigating plant intelligence.
The question that arises though, when we find more and more examples of intelligent behavior across the tree of of life, is intelligence actually that useful of a concept?
The question that arises though, when we find more and more examples of intelligent behavior across the tree of of life, is intelligence actually that useful of a concept?
Depends on your definition of intelligence. But even if more intelligence means a higher chance of finding others first, there's still good old luck. Especially the luck of being the first born:
Humans have been roughly at their current biological level of intelligence for at least thousands of years. But our ability to detect aliens has increased dramatically. Similar, a slightly more intelligence alien species that's lagging us by a few million years would have a hard time detecting us anytime.
Or, conceivably dolphins and wales might be more intelligent than us. Or you could conceive of a highly intelligent squid like species on another world. Problem is, if their whole world is an ocean, they are going to have a harder time with metallurgy or electricity.
(It's probably not impossible to build up technology under water, but it's probably harder and requires more cleverness and time. And even if it doesn't, because there's an easy way that humans just don't see; there are probably some circumstances that make it much harder. Eg assume a world that's all ice or desert, so it can only sustain a million people instead of billions.)
Humans have been roughly at their current biological level of intelligence for at least thousands of years. But our ability to detect aliens has increased dramatically. Similar, a slightly more intelligence alien species that's lagging us by a few million years would have a hard time detecting us anytime.
Or, conceivably dolphins and wales might be more intelligent than us. Or you could conceive of a highly intelligent squid like species on another world. Problem is, if their whole world is an ocean, they are going to have a harder time with metallurgy or electricity.
(It's probably not impossible to build up technology under water, but it's probably harder and requires more cleverness and time. And even if it doesn't, because there's an easy way that humans just don't see; there are probably some circumstances that make it much harder. Eg assume a world that's all ice or desert, so it can only sustain a million people instead of billions.)
“For instance, on the planet Earth, man had always assumed that he was more intelligent than dolphins because he had achieved so much—the wheel, New York, wars and so on—whilst all the dolphins had ever done was muck about in the water having a good time. But conversely, the dolphins had always believed that they were far more intelligent than man—for precisely the same reasons.”
― Douglas Adams, The Hitchhiker's Guide to the Galaxy
― Douglas Adams, The Hitchhiker's Guide to the Galaxy
Agreed, and by some interesting heuristics, we already know animals significantly smarter then us. Watching the chimps absolutely dominate humans in memory matching games is fascinating.
I think it's super cool personally, and inspiring. Imho, the notion seems rather silly at this point.
I would like to see your calculations for the number of intelligent civilizations in our galaxy. How many? What percentage? Do they exist on any kind of scale? Are there any major differences between them?
Thanks!
Thanks!
Make sure to click the lead image to see the star also.
Aha, apparently there is an image sidebar which is hidden on mobile, where is given the following reason for the star's haloed appearance:
"The image was captured by blocking the light from the young, Sun-like star (top-left of centre) using a coronagraph, which allows for the fainter planets to be detected. The bright and dark rings we see on the star’s image are optical artefacts."
"The image was captured by blocking the light from the young, Sun-like star (top-left of centre) using a coronagraph, which allows for the fainter planets to be detected. The bright and dark rings we see on the star’s image are optical artefacts."
Thanks for the notice, I missed it, and it's much more impressive this way! I thought I was looking at the star and a single planet.
The image literally sent chills down my spine.
A recent video talking about what it could take to get high resolution imagery of exoplanets. The video title is a bit hand wavy, but it basically involves using the sun as a gravitational lens:
https://www.youtube.com/watch?v=NQFqDKRAROI
https://www.youtube.com/watch?v=NQFqDKRAROI
This was great. Thanks for sharing!
Amazing video. Thanks for sharing.
That was a great, informative video, thanks for sharing.
Telescopes like VLT, the LIGO experiment, CERN LHC and ATLAS, and a few others really represent the state of the art in terms of precision as applied the science.
I got fascinated with the challenges associated with building high precision systems (which has been an ongoing pursuit since the beginning of the industrial revolution that has led to untold scientific and economic wealth). It's not easy. Progress depends on large numbers of people working together across multiple fields to build systems that are often only a few percent better than the previous generation. Sometimes, there are breakthroughs and fields progress rapidly, only to end up stagnated as they reach their theoretical limits or other bottlenecks.
What humans have achieved, over the course of civilization is really quite extraordinary and we shouldn't ignore that what people were doing at the beginning of civilization required precision as well, but the precision depended far more on the physical skills of the artisan, than their ability to use their brain and capital to make highly precise objects.
Two of the most powerful techniques that came from the mastery of precision are interferometry (the process of collecting and combining multiple light waves) and spectroscopy (the process of collecting frequency-resolved photon distributions).
I'm building an alt-az mount for a raspberry pi solar scope at home; it weighs a few pounds. Each of the scopes at ESO (there are 4, allowing them to exploit interferometry to increase their angular resolution) is a building that is an alt-az mount that weighs 350 tons.
I got fascinated with the challenges associated with building high precision systems (which has been an ongoing pursuit since the beginning of the industrial revolution that has led to untold scientific and economic wealth). It's not easy. Progress depends on large numbers of people working together across multiple fields to build systems that are often only a few percent better than the previous generation. Sometimes, there are breakthroughs and fields progress rapidly, only to end up stagnated as they reach their theoretical limits or other bottlenecks.
What humans have achieved, over the course of civilization is really quite extraordinary and we shouldn't ignore that what people were doing at the beginning of civilization required precision as well, but the precision depended far more on the physical skills of the artisan, than their ability to use their brain and capital to make highly precise objects.
Two of the most powerful techniques that came from the mastery of precision are interferometry (the process of collecting and combining multiple light waves) and spectroscopy (the process of collecting frequency-resolved photon distributions).
I'm building an alt-az mount for a raspberry pi solar scope at home; it weighs a few pounds. Each of the scopes at ESO (there are 4, allowing them to exploit interferometry to increase their angular resolution) is a building that is an alt-az mount that weighs 350 tons.
> few pounds
> 350 tons
what is the significance of this?
> 350 tons
what is the significance of this?
Shows the scale of the telescopes by comparing the massiveness of a homemade vs. state-of-the-art whole-building altitude-azimuth mount. It's amazing that something that ways 350 tons can be aimed with precision at photographic targets that are constantly moving with the rotation of the earth.
Someone want to do the math for me? How many arc-angles per pixel in this image? And then, with those arc-angles, what sized object could you resolve (as larger than one pixel) on the moon?
> ESO ... has taken the first direct image of a planetary system around a star like our Sun, located about 300 light-years away...
> The two gas giants orbit their host star at distances of 160 and about 320 times the Earth-Sun distance.
For our purposes, a parsec [pc] is 3 ly, so the host star is at 100 pc. The inner planet is at 160 AU, which we'll round to 100 AU.
So the angular separation is 100 AU / 100 pc = 1 AU/pc = 1 arcsec, and their resolution must exceed this.
And then we have this handy chart:
https://astronomy.stackexchange.com/questions/20695/how-big-...
This illustrates that the key issue is not resolution itself. It's contrast, at this high resolution. Because the planet must be distinguished from the host star.
I don't know what the contrast difference here is. For Earth-like exoplanets (smaller targets at 1AU), the contrast difference is 10^10. That is, for every 10 billion photons from the host star, you get one reflected from the exoplanet.
[edited to add: using the link provided by @teraflop, Table 1, column 3 seems to show a contrast of about 10-12 in magnitude units, which is 10^4 to 10^5 in physical units like photons]
> The two gas giants orbit their host star at distances of 160 and about 320 times the Earth-Sun distance.
For our purposes, a parsec [pc] is 3 ly, so the host star is at 100 pc. The inner planet is at 160 AU, which we'll round to 100 AU.
So the angular separation is 100 AU / 100 pc = 1 AU/pc = 1 arcsec, and their resolution must exceed this.
And then we have this handy chart:
https://astronomy.stackexchange.com/questions/20695/how-big-...
This illustrates that the key issue is not resolution itself. It's contrast, at this high resolution. Because the planet must be distinguished from the host star.
I don't know what the contrast difference here is. For Earth-like exoplanets (smaller targets at 1AU), the contrast difference is 10^10. That is, for every 10 billion photons from the host star, you get one reflected from the exoplanet.
[edited to add: using the link provided by @teraflop, Table 1, column 3 seems to show a contrast of about 10-12 in magnitude units, which is 10^4 to 10^5 in physical units like photons]
300 AU?
Isn't that exeedingly far? Like 10 times farther away from Pluto?
Would we even be able to detect such a planet if it orbited the Sun?
Isn't that exeedingly far? Like 10 times farther away from Pluto?
Would we even be able to detect such a planet if it orbited the Sun?
In the article they say that these planets are young and hot and they detected them in infrared by blocking light from the host star using special device. We would easily detect such super-massive hot planet at 300 AU in the solar system, but there is no reason for them to exist here since solar system is much older.
Just to emphasize one point you made: It appears the first companion planet (160 AU) was originally detected using direct imaging last year (preprint [1] is dated Dec 2019, see sec. 4 for methods).
And I guess the second one was announced in OP, making it a multi-planet system.
The point of this comment is to note that these 2 planets were originally detected by direct imaging, not by other techniques.
[1] https://arxiv.org/pdf/1912.04284.pdf
And I guess the second one was announced in OP, making it a multi-planet system.
The point of this comment is to note that these 2 planets were originally detected by direct imaging, not by other techniques.
[1] https://arxiv.org/pdf/1912.04284.pdf
I was thinking that in out case hot or cold is not the main issue, but the area where to look.
If you look at a star 300 light years away, you just have to search a couple of pixels away from the star.
But if you searched for such a planet at 300 AU from out Sun, you would have a massive amount of space to search throug -- like a massive cilindrical wall of space around the Sun(if it was not exactly on our plane around the Sun).
But in anycase, I was wondering if we had such a planet in our solar system, but obviously cold by now, could we detect it?
If you look at a star 300 light years away, you just have to search a couple of pixels away from the star.
But if you searched for such a planet at 300 AU from out Sun, you would have a massive amount of space to search throug -- like a massive cilindrical wall of space around the Sun(if it was not exactly on our plane around the Sun).
But in anycase, I was wondering if we had such a planet in our solar system, but obviously cold by now, could we detect it?
If it has a gravitational influence on other planets, then yes, same way as the discovery of Neptune.
https://en.wikipedia.org/wiki/Discovery_of_Neptune
Now, 300 AU is far away, but then, 14 times the mass of jupiter is heavy. But I'm not knowledged enough to do the math here.
On a 2nd thought, maybe not. How long would a year be for a planet that far outside? Maybe several hundred years? We'd need to be in the right window of time to spectate such effects in first place.
https://en.wikipedia.org/wiki/Discovery_of_Neptune
Now, 300 AU is far away, but then, 14 times the mass of jupiter is heavy. But I'm not knowledged enough to do the math here.
On a 2nd thought, maybe not. How long would a year be for a planet that far outside? Maybe several hundred years? We'd need to be in the right window of time to spectate such effects in first place.
To be equivalent to the gravitational impact of Neptune the mass would have to be about 70,000 times the mass of Neptune. This is more equivalent to trying to find Planet Nine [0], which, although was also “discovered” through gravitational effects, those effects are much subtler and the planet might not exist and if it does, hasn’t been found.
[0] - https://en.m.wikipedia.org/wiki/Planet_Nine
[0] - https://en.m.wikipedia.org/wiki/Planet_Nine
(if it was not exactly on our plane around the Sun)
On that matter, are there any significant objects (natural or artificial) orbiting way outside the plane of the solar system?
On that matter, are there any significant objects (natural or artificial) orbiting way outside the plane of the solar system?
Pluto is inclined at 17 degrees to the ecliptic plant.
Haley's Comet is inclined at -18 degrees, and is highly elliptic which means that most of the time it is south of the ecliptic plane.
The Kuiper Belt and Scattered Disk have a lot of objects inclined to the ecliptic, you can see a distribution here [0].
This [1] list has some even more inclined objects.
[0] https://en.wikipedia.org/wiki/Scattered_disc#/media/File:The...
[1] https://en.wikipedia.org/wiki/List_of_exceptional_asteroids#...
Haley's Comet is inclined at -18 degrees, and is highly elliptic which means that most of the time it is south of the ecliptic plane.
The Kuiper Belt and Scattered Disk have a lot of objects inclined to the ecliptic, you can see a distribution here [0].
This [1] list has some even more inclined objects.
[0] https://en.wikipedia.org/wiki/Scattered_disc#/media/File:The...
[1] https://en.wikipedia.org/wiki/List_of_exceptional_asteroids#...
Eris is inclined 44 degrees. I think the highest inclination artificial satelite is Parker Solar Probe, about 3.4 degrees
Your comment jogged my memory. Ulysses, a cleverly-named solar-polar mission, used a deployment from the Shuttle, and a gravity assist from Jupiter, to reach an inclination of 80 degrees.
From https://www.cosmos.esa.int/web/ulysses/the-ulysses-mission:
> Because direct injection into a solar polar orbit from the Earth is not feasible, a gravity-assist is required to achieve a high-inclination orbit. As a result, Ulysses was launched at high speed towards Jupiter in October 1990, after being carried into low-Earth orbit by the space shuttle Discovery. Following the fly-by of Jupiter in February 1992 /3/, the spacecraft is now travelling in an elliptical, Sun-centred orbit inclined at 80.2 degrees to the solar equator.
From https://www.cosmos.esa.int/web/ulysses/the-ulysses-mission:
> Because direct injection into a solar polar orbit from the Earth is not feasible, a gravity-assist is required to achieve a high-inclination orbit. As a result, Ulysses was launched at high speed towards Jupiter in October 1990, after being carried into low-Earth orbit by the space shuttle Discovery. Following the fly-by of Jupiter in February 1992 /3/, the spacecraft is now travelling in an elliptical, Sun-centred orbit inclined at 80.2 degrees to the solar equator.
Not sure that "per pixel" is the most meaningful metric, because in astronomy, resolution is typically limited by telescope optics and atmospheric conditions, rather than pixel count.
But if I'm reading the paper correctly ([1], table 2) the observed angular resolution -- the FWHM, i.e. the "blurriness" of an assumed point source -- was on the order of 0.05 arcseconds. Given the distance from the Earth to the Moon (about 384,000 km), that would correspond to a resolution of about a hundred meters.
[1]: https://www.eso.org/public/archives/releases/sciencepapers/e...
But if I'm reading the paper correctly ([1], table 2) the observed angular resolution -- the FWHM, i.e. the "blurriness" of an assumed point source -- was on the order of 0.05 arcseconds. Given the distance from the Earth to the Moon (about 384,000 km), that would correspond to a resolution of about a hundred meters.
[1]: https://www.eso.org/public/archives/releases/sciencepapers/e...
For your first question:
Tan^-1[(160/2 Au)/(300 lightyears)] = 2.4×10^-4° for the distance between the inner planet and the star. You can divide this by the pixel length.
With respect to your second question:
Resolution is not tied to do pixel size for this type of measurement. You can resolve an object of any size if it is emitting enough photons.
Tan^-1[(160/2 Au)/(300 lightyears)] = 2.4×10^-4° for the distance between the inner planet and the star. You can divide this by the pixel length.
With respect to your second question:
Resolution is not tied to do pixel size for this type of measurement. You can resolve an object of any size if it is emitting enough photons.
I meant resolve as in "determine what it is," like, how big would the letters have to be on the moon in order for you to read them.
So then resolve that two objects are distinct.
I can't continue down this rabbit hole so I'm asking for a handout. I remember reading about the limitations of light and contrast to resolve smaller details on the moon or other solar systems like this. I've since lost the details and links to time.
Is there any upper limit, physically, to this? Would it be possible on paper to design a system that could take pictures of the moon where you could see individual strands of hair on a human?
I'm curious if we might at some point construct enormous arrays of telescopes spanning large (human perspective) sections of space that could give us a window into our galaxy.
Is there any upper limit, physically, to this? Would it be possible on paper to design a system that could take pictures of the moon where you could see individual strands of hair on a human?
I'm curious if we might at some point construct enormous arrays of telescopes spanning large (human perspective) sections of space that could give us a window into our galaxy.
There are several physical limits to how small objects can be resolved.
Here is a discussion thread with regards to the smallest lunar object visible - seems to be around 350 meter resolution for an earth bound telescope.
https://www.cloudynights.com/topic/712653-what-is-the-smalle...
Here is a discussion thread with regards to the smallest lunar object visible - seems to be around 350 meter resolution for an earth bound telescope.
https://www.cloudynights.com/topic/712653-what-is-the-smalle...
But could images from several telescopes be combined through a Kalman filter or something to resolve higher details?
I am imagining some kind of internet enabled telescope that knows it's GPS location and orientation, and phones home it's imagery to a central server. If millions of people bought and used a product like that, is it theoretically possible to see the lunar rover?
I am imagining some kind of internet enabled telescope that knows it's GPS location and orientation, and phones home it's imagery to a central server. If millions of people bought and used a product like that, is it theoretically possible to see the lunar rover?
https://en.wikipedia.org/wiki/Astronomical_interferometer
TL;DR: for optical wavelengths, with typical image sensors that only detect amplitude and not phase of the electromagnetic wave, you need to do some really hard work to ensure optical coherency. For radio telescopes, it's a lot easier since you measure both amplitude and phase.
Another technique that's a lot easier to accomplish for amateurs is lucky imaging:
https://en.wikipedia.org/wiki/Lucky_imaging
TL;DR: for optical wavelengths, with typical image sensors that only detect amplitude and not phase of the electromagnetic wave, you need to do some really hard work to ensure optical coherency. For radio telescopes, it's a lot easier since you measure both amplitude and phase.
Another technique that's a lot easier to accomplish for amateurs is lucky imaging:
https://en.wikipedia.org/wiki/Lucky_imaging
In this context, it's relevant to note that the VLT was built with interferometry in mind, and they are now getting it to work reliably. See for instance the page about the GRAVITY instrument: https://www.eso.org/public/teles-instr/paranal-observatory/v...
https://en.wikipedia.org/wiki/Diffraction-limited_system
There is a fundamental relationship between wavelength of light and focus-ability/magnification.
You could in principle build an increasingly larger lense to get around the problem, but eventually that hits practical limits.
There is a fundamental relationship between wavelength of light and focus-ability/magnification.
You could in principle build an increasingly larger lense to get around the problem, but eventually that hits practical limits.
Can't you create ever larger arrays of reasonably sized lenses? And "array" just means "two or more widely separated by a known distance", so opposite sides of (polar?) orbit should work.
For varying definitions of pratical. For example, you can use a star as a gravitational lens.
HDR for astrophotography
i'm not expert. i have a back yard observatory with a 12 inch and an 8 inch SCT telescopes.
there is a limit to how far information can propagate. but with wider and wider scopes we can deal with the wave properties of light and how those waves get wider and wider as you go farther away. (see the inverse square law)
so, we could probably see a human hair on the moon, but the mechanism to do so would be the size of a city like LA or something.
the best way we have to deal with that is actually interferometry. you take measurements of the light wave emitted by a source at several points along it's wave front and infer what the source would look like closer up.
it's very fuzzy but gives us pictures of some very large very far away structures in the universe.
so, maybe if we had enough telescopes pointed at the moon, we could see fine structures like that? but my feeling is that a lot of that information on that scale is just lost from the perspective of each scope, so you really need to capture all of it at a weirdly large scale.
there is a limit to how far information can propagate. but with wider and wider scopes we can deal with the wave properties of light and how those waves get wider and wider as you go farther away. (see the inverse square law)
so, we could probably see a human hair on the moon, but the mechanism to do so would be the size of a city like LA or something.
the best way we have to deal with that is actually interferometry. you take measurements of the light wave emitted by a source at several points along it's wave front and infer what the source would look like closer up.
it's very fuzzy but gives us pictures of some very large very far away structures in the universe.
so, maybe if we had enough telescopes pointed at the moon, we could see fine structures like that? but my feeling is that a lot of that information on that scale is just lost from the perspective of each scope, so you really need to capture all of it at a weirdly large scale.
The mass of the larger of the 2 planets seems to be on the verge of brown dwarf classification https://en.wikipedia.org/wiki/Brown_dwarf
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Do both these planets just happen to be passing in front of the star then, because they would typically be a mile or so outside the image at that scale wouldn't they?
No, they are imaged in reflected light, rather than a transit (silhouette).
The parent star is masked off, and I’m pretty sure it’s an image generated from multiple telescopes, “interferometry”, as others have mentioned.
The parent star is masked off, and I’m pretty sure it’s an image generated from multiple telescopes, “interferometry”, as others have mentioned.
No, this was actually shot with SPHERE, which is a single telescope instrument: https://www.eso.org/public/teles-instr/paranal-observatory/v...
Interesting. It’s attached to one of the VLTs
https://en.wikipedia.org/wiki/Very_Large_Telescope
Unclear if they use the auxiliaries as part of the process.
https://en.wikipedia.org/wiki/Very_Large_Telescope
Unclear if they use the auxiliaries as part of the process.
Indeed I should have asked if both planets just happened to be passing behind the star? Alternatively, have they just been superimposed beside the star at arbitrary positions? I'm still none the wiser.
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That star system is young, and the planets are therefore hot enough to produce their own infrared light. That light is what the telescope saw.
So, there was no need for the planets to pass in front of the star to be detected.
In fact, if you click on the picture in the article, you see two planets and the star quite a distance from each other. Those planets are much further from their star than any of the (known) planets in our own solar system.
So, there was no need for the planets to pass in front of the star to be detected.
In fact, if you click on the picture in the article, you see two planets and the star quite a distance from each other. Those planets are much further from their star than any of the (known) planets in our own solar system.
Why do they appear so large and so close together in the photo? (Assuming that is an image of the star and one of the planets). Are they really point sources, blooming to cover more pixels?
Click on the image to reveal the entire image: there’s a star and two planets.
(It’s ridiculous that they would publish the image cropped like this.)
(It’s ridiculous that they would publish the image cropped like this.)
Why a picture of this and not Alpha Centauri at ~4 ly?
We don't know for sure of any planets around Alpha Centauri but, if there were any, SPHERE should be able to resolve a 5000 times fainter (the system is 75 times closer) IR source orbiting as close as 2 UA (roughly the same angular separation from the star as the closest planet detected at 160 UA) from Alpha Centauri A or B.
As for Proxima, Proxima b orbits at 0.05 UA (which is very close). I don't think we could separate its light from the parent star.
As for Proxima, Proxima b orbits at 0.05 UA (which is very close). I don't think we could separate its light from the parent star.
Alpha Centauri has a binary system with another third sun orbiting the other two at half a light-year or so. Not very "sun-like".
However, it has planets thought to be in the Goldi-locks zone around one of the stars. Seems like if they can get that kind of resolution at 300ly, they should be able to do infinitely better at 4. Just a thought, I am sure I am missing something.
A comment upthread mentions that one of the biggest obstacles to detecting planets is the huge contrast between the planet and its host star: detecting 10-14 orders of magnitude difference between the luminosity of a star and orbiting planet cannot be made simpler by adding in 2 additional stars.
Another commenter said:
"The two gas giants orbit their host star at distances of 160 and about 320 times the Earth-Sun distance."
Just a guess but perhaps being in the Goldilocks zone the planets are harder to discern from Alpha Centauri.
I figure the technology that blocks the star light may mean this isn't the case though.
Just a guess but perhaps being in the Goldilocks zone the planets are harder to discern from Alpha Centauri.
I figure the technology that blocks the star light may mean this isn't the case though.
I kind of love that the first system photographed(?) is in a different orientation and that we have a “top” down view of it.
It doesn’t have to be in a different orientation, it could be parallel with ours but not coplaner. The important thing for this kind of picture is that a normal with the tail near the system from plane of rotation points roughly in our direction.
I think the multi-planet system part is what makes it a first.
How do you mean? That it it was photographed in such a manner? We definitely know of plenty of several systems with multiple planets.
Yes that's exactly how I understood it. Otherwise anyone who has taken a picture of the night sky probably beat this image.
So it's more like a triple star system of two brown dwarfs and one star?
Incredible. 300 light years away and photographed by a ground based telescope. We keep pushing the boundaries. I’m excited for the next couple of decades of astronomy. What more will we see?
Proof of life outside earth would be the coolest
Some people think that would be very bad as it would suggest that the Great Filter is in our future rather than our past:
https://en.wikipedia.org/wiki/Great_Filter
https://en.wikipedia.org/wiki/Great_Filter
We can't honestly have any practical discussion about the concept of a Great Filter until we get to the point that our observational capability would be sufficient to reliably detect another civilization at a similar level of development to our own within a sufficient size search space: within our own galaxy for instance. Considering that 68% of the universe's energy and 27% of its mass is still basically unaccounted for, it's clear we have a very long way to go before this idea is worth bringing out of the halls of existential philosophy.
Let's say for the sake of argument that a civilization exists in our nearest neighbor system, Proxima Centauri. Let's assume that it has developed with a similar impact to their system as humans have had to our own -- radio emissions, a handful of interplanetary and interstellar space probes, nuclear tests, etc. Could we detect them? Everything I have read concludes that we currently could not. The concept of being able to receive interstellar TV transmissions is such a sci-fi trope I don't think very many people consider that it is essentially impossible.
Let's say for the sake of argument that a civilization exists in our nearest neighbor system, Proxima Centauri. Let's assume that it has developed with a similar impact to their system as humans have had to our own -- radio emissions, a handful of interplanetary and interstellar space probes, nuclear tests, etc. Could we detect them? Everything I have read concludes that we currently could not. The concept of being able to receive interstellar TV transmissions is such a sci-fi trope I don't think very many people consider that it is essentially impossible.
The argument is that on this timescales they would be here for now.
But all this doesn’t really matter since you can’t apply frequentist logic in bayesian situation: what we observe is exactly the same as someone in the long tail of distribution would observe, i.e. we can’t distinguish between this being unlikely situation and being first, or this being proof of Great Filter.
But all this doesn’t really matter since you can’t apply frequentist logic in bayesian situation: what we observe is exactly the same as someone in the long tail of distribution would observe, i.e. we can’t distinguish between this being unlikely situation and being first, or this being proof of Great Filter.
Hmm, maybe I'm missing something, but the main argument for the Great Filter is that we haven't observed any extraterrestrial life. If we started observing that life, that might just mean that so far our observation technology has not been good enough previously.
We can't detect life at our stage of development from afar, or from earlier stages, but things that extremely advanced civilizations build like dyson spheres can't be hidden really.
The issue is that the universe is extremely old compared to how long it took for earth to develop life. It's ample time for civilizations to develop technologies extremely far more advanced than ours. So why isn't there a single civilization that's so advanced that it builds these things?
So there must be some "filter" that prevents civilizations from doing that, whether they are alive or dead. Maybe they just don't want to, but then ALL of them have to not want to do it, which would be weird.
If we detect life close to us, it makes it more likely that there is tons of life around the galaxy, which makes it more likely that the filter is ahead of us. If we detect no life close to us, it makes it more likely that the filter is past us.
See this Kurzgesagt video about the topic: https://www.youtube.com/watch?v=UjtOGPJ0URM
The issue is that the universe is extremely old compared to how long it took for earth to develop life. It's ample time for civilizations to develop technologies extremely far more advanced than ours. So why isn't there a single civilization that's so advanced that it builds these things?
So there must be some "filter" that prevents civilizations from doing that, whether they are alive or dead. Maybe they just don't want to, but then ALL of them have to not want to do it, which would be weird.
If we detect life close to us, it makes it more likely that there is tons of life around the galaxy, which makes it more likely that the filter is ahead of us. If we detect no life close to us, it makes it more likely that the filter is past us.
See this Kurzgesagt video about the topic: https://www.youtube.com/watch?v=UjtOGPJ0URM
I don't like that theory, it's completely limited by our current understanding of how a "more advanced" civilization would look like. If we haven't seen signs of what we think more advanced civilizations would look like, the simplest explanation is that what we think advanced civilizations are like is wrong
I agree. Saying that a Dyson Sphere is something that an 'extremely advanced civilization would build' presumes that we can project the course of civilization. Seems presumptuous and short sighted to me.
Yeah a Dyson Sphere contains the presumption that an advanced alien civilization's population would grow exponentially like earths population did in the 20th century.
I don't know how you square a utterly stupid idea like exponential population growth with the word advanced in advanced civilization. Instead this sounds like blinkered mid twentieth century thinking. Or the old science fiction trope of seeing the future as like the present but more of it.
I don't know how you square a utterly stupid idea like exponential population growth with the word advanced in advanced civilization. Instead this sounds like blinkered mid twentieth century thinking. Or the old science fiction trope of seeing the future as like the present but more of it.
> The issue is that the universe is extremely old compared to how long it took for earth to develop life
I wouldn't call the universe very old. It's only like 13.x billion years old. If you take into account the amount of time it takes for heavier elements to be created, the time for the universe to settle down I'd say we are in the first cohort. It took us 4.5 billion years to evolve and if humanity got wiped out life on Earth would most likely continue on as it has for millions of years before with megafauna.
Looking at how life appeared immediately after the planet cooled down and had liquid oceans most likely indicates abiogenesis is common, multicellular may be much more rare and intelligence probably is exceedingly rare given how expensive big brains are. I just don't think there was enough time in the early universe for intelligent civilizations to have evolved.
I wouldn't call the universe very old. It's only like 13.x billion years old. If you take into account the amount of time it takes for heavier elements to be created, the time for the universe to settle down I'd say we are in the first cohort. It took us 4.5 billion years to evolve and if humanity got wiped out life on Earth would most likely continue on as it has for millions of years before with megafauna.
Looking at how life appeared immediately after the planet cooled down and had liquid oceans most likely indicates abiogenesis is common, multicellular may be much more rare and intelligence probably is exceedingly rare given how expensive big brains are. I just don't think there was enough time in the early universe for intelligent civilizations to have evolved.
My preferred solution to the great filter is to assume that things like Dyson spheres can't feasibly be built, at any level of technological development.
So there may be millions of civilizations that can get into orbit with chemical or nuclear rockets, but not a single one that can carry out a megaproject that could be seen from Earth.
So there may be millions of civilizations that can get into orbit with chemical or nuclear rockets, but not a single one that can carry out a megaproject that could be seen from Earth.
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I've always thought it made more sense that microbial life with took billions of years to develop, and originated someplace other than earth. The reason we don't see hyper-advanced civilizations is because intelligent life is only just starting to pop up alongside us, right now, and perhaps we're one of the earlier manifestations.
It's not my domain, but there are apparently some markers of genetic complexity that give some weight to this theory: https://arxiv.org/ftp/arxiv/papers/1304/1304.3381.pdf
It's not my domain, but there are apparently some markers of genetic complexity that give some weight to this theory: https://arxiv.org/ftp/arxiv/papers/1304/1304.3381.pdf
Personally I think life originated on earth. We shouldn't look at contemporary prokaryotes to determine how complex prokaryotes were at the start of life. They had billions of years to develop as well and if the more complex ones are fitter than the less complex ones, they will win. E.g. you think rotting plants is a normal thing but there was a time when plants wouldn't and just form giant heaps, forming the coal reservoirs of today.
Anyways, let's assume life originated at some other planet and it has started life at half of the galaxy at the time it reached earth (so we weren't lucky to be "close" to the origin).
Earth is 4500 million years old, and life is assumed to have existed here since 4400 million years. So intelligent life took 4400 million years to "develop" here on earth. Light speed allows you to colonize the milky way comfortably within a million years. What if it takes 100 million years less on some other planet? Or it took just 10 million years less?
Either earth is very close to the real origin (or has been at the start of life), or the filter is in the past, or some other explanation.
Anyways, let's assume life originated at some other planet and it has started life at half of the galaxy at the time it reached earth (so we weren't lucky to be "close" to the origin).
Earth is 4500 million years old, and life is assumed to have existed here since 4400 million years. So intelligent life took 4400 million years to "develop" here on earth. Light speed allows you to colonize the milky way comfortably within a million years. What if it takes 100 million years less on some other planet? Or it took just 10 million years less?
Either earth is very close to the real origin (or has been at the start of life), or the filter is in the past, or some other explanation.
This theory is actually proposed by Nick Lane et al - it says that microbial life is probably ubiqutuous and that complex life is not and was a happy accident on Earth, which means its very improbable on other planets. The prereqs for it happened only once on Earth, when one microbe swallowed another and the smaller one became mitochondria enabling complex cell structure and shape. Given that microbial life exist in extreme environments on Earth and that its prereq is just a hot molecular soup, its probable it exists everywhere. On the other hand, the 'happy incident' didn't repeat on Earth to create another complex cell form - all higher life uses the same cell structure.
That's what the great filter theory means when they talk about it being behind us -- we don't see life in other places because developing to where we are now is almost impossible.
I don't buy it though -- we're in an average planet on an average star, nothing about our environment seems to be particularly rare.
I don't buy it though -- we're in an average planet on an average star, nothing about our environment seems to be particularly rare.
I think the statement that we are on an average planet deserves more scrutiny. We have yet to observe another planet like ours.
There are a number of Earth's attributes that we don't understand and have poor extra-solar data on. Particularly, the following:
Technically active plates after 4.5 Byrs. Effective magnetic core after 4.5 Byrs. Large amounts of surface water, presumably from our late heavy bombardment. Small enough to leave with a chemical rocket while meeting the above.
There are a number of Earth's attributes that we don't understand and have poor extra-solar data on. Particularly, the following:
Technically active plates after 4.5 Byrs. Effective magnetic core after 4.5 Byrs. Large amounts of surface water, presumably from our late heavy bombardment. Small enough to leave with a chemical rocket while meeting the above.
All those 'limitations' are too much anthropomorphic for my taste - life can probably exist in far more niches.
Also, at our current tech level, planets are very hard to even observe for existence, let alone their geographical features.
Also, at our current tech level, planets are very hard to even observe for existence, let alone their geographical features.
I tend to agree with both your points, but was addressing the specific claim that Earth-like conditions are average, or at least not particularly rare.
We simply don’t have data to support that claim, and the parameters required to make earth habitable for life (as we know it) are vastly more numerous than most people acknowledge.
We simply don’t have data to support that claim, and the parameters required to make earth habitable for life (as we know it) are vastly more numerous than most people acknowledge.
Lets start with Oscam Razor then: its wast universe. Even on Earth, there are untouched places. All other theories compared to this one, which is easy to understand and also already known to be in effect on this planet, are as close to the truth as theory that great filter are evil pink elephants in the center of the galaxy.
> I've always thought it made more sense that microbial life with took billions of years to develop, and originated someplace other than earth. The reason we don't see hyper-advanced civilizations is because intelligent life is only just starting to pop up alongside us, right now, and perhaps we're one of the earlier manifestations.
This explanation does not work, because of the timescales.
Five thousand years ago, we built the Pyramids. Fifty years ago, we landed on the Moon.
In contrast, it took four billion years to go from single-celled life, to the pyramids.
The odds of us being first by happenstance are astonishingly small. It's much more likely that either we are unique, or that civilizations don't leave much of a trace outside of their solar systems, regardless of whether or not they die out in the blink of a cosmic eye.
This explanation does not work, because of the timescales.
Five thousand years ago, we built the Pyramids. Fifty years ago, we landed on the Moon.
In contrast, it took four billion years to go from single-celled life, to the pyramids.
The odds of us being first by happenstance are astonishingly small. It's much more likely that either we are unique, or that civilizations don't leave much of a trace outside of their solar systems, regardless of whether or not they die out in the blink of a cosmic eye.
We simply haven't developed enough yet. It wouldn't be good game design to encounter other civs at this stage.
Tutorial level civilization.
You must complete energy collection on current planet for XP to advance to level 2.
You must complete energy collection on current planet for XP to advance to level 2.
> If we detect life close to us, it makes it more likely that there is tons of life around the galaxy, which makes it more likely that the filter is ahead of us.
Isn't is the other way around? I though that the main argument for the filter ahead of us is that we haven't found any civilization, which means civilizations cannot develop past some level at which they can be detected by us. But if we'll have found one, this means that such level of civilization can be passed, and therefore reduces the chances that there is a filter.
Isn't is the other way around? I though that the main argument for the filter ahead of us is that we haven't found any civilization, which means civilizations cannot develop past some level at which they can be detected by us. But if we'll have found one, this means that such level of civilization can be passed, and therefore reduces the chances that there is a filter.
I think by "life" the parent was talking about microbes on Mars or waterbears on comets or something. Technology developing life is a different thing entirely. If we find primitive life nearby, then there probably is primitive life everywhere, and very little technology developing life (because of the "filter").
Yeah, detecting life could mean many things:
- The filter is ahead us
- There is no filter
- The filter is behind us, but ahead of the other planet
- Both planets have successfully got past the filter
We'll still be debating :). Then we'll go crazy trying find evidence of life in more planets.
- The filter is ahead us
- There is no filter
- The filter is behind us, but ahead of the other planet
- Both planets have successfully got past the filter
We'll still be debating :). Then we'll go crazy trying find evidence of life in more planets.
An addition to there is no filter (yet):
- We're one of the first nearby and we're going to help build a filter
The various AI we give birth to over the next two centuries are going to dominate several galaxies. There are many filters - competing standards - throughout the universe, our galaxy doesn't yet have one. Humans will cease to exist as we think of them now, within those two centuries (and not due to climate change or any other similar event).
- We're one of the first nearby and we're going to help build a filter
The various AI we give birth to over the next two centuries are going to dominate several galaxies. There are many filters - competing standards - throughout the universe, our galaxy doesn't yet have one. Humans will cease to exist as we think of them now, within those two centuries (and not due to climate change or any other similar event).
that said, the likelihood of there being _no_ filter is still lower than the others.
if we detect life so near to us and _yet_ we still have yet to encounter life from another planet means there's likely still _some_ kind of filter. So I don't think the likelihood of no filter is high if we detect life
if we detect life so near to us and _yet_ we still have yet to encounter life from another planet means there's likely still _some_ kind of filter. So I don't think the likelihood of no filter is high if we detect life
Rather then apocaliptyical filter, the most probable reason is that space is so wast that even if advanced life was common, chance of meeting/observing one would be next to 0. Think about our civ living on a sand grain in the desert - the chance is almost 0 to encounter another civ living on sand grain on random desert location no matter how advanced your tech is.
yikes - that's true, we could still move life beyond earth and still never meet another civ. I didn't realize this at first but I was conflating the two
just learned about the "great filter", very interesting. I think it does mean that our observation tech is not good previously - it also sounds like if we did start observing life, the fact that we have yet to be visited / colonized by that life form means only re-affirms the unlikelihood of interplanetary travel..
according to [wikipedia](https://en.wikipedia.org/wiki/Great_Filter):
> So by this argument, finding multicellular life on Mars (provided it evolved independently) would be bad news, since it would imply steps 2–6 are easy, and hence only 1, 7, 8 or 9 (or some unknown step) could be the big problem.[4]
according to [wikipedia](https://en.wikipedia.org/wiki/Great_Filter):
> So by this argument, finding multicellular life on Mars (provided it evolved independently) would be bad news, since it would imply steps 2–6 are easy, and hence only 1, 7, 8 or 9 (or some unknown step) could be the big problem.[4]
Imagine that, knowing there's intelligent life out there, but knowing we will never meaningfully interact with them because it's impossible to travel any useful distance or communicate in any real way. Even if we could travel vast distances, It seems likely if we discover any life out there it may be long dead by the time we get there.
Even if we passed a Great Filter it doesn't necessarily mean that there wouldn't be an other one in front of us.
Also not finding other civilizations wouldn't be a proof that we passed any filter at all, maybe plenty of civilizations have been incredibly successful already, they're just so far beyond our comprehension of the world and consciousness that we can't meaningfully interact with them.
Also not finding other civilizations wouldn't be a proof that we passed any filter at all, maybe plenty of civilizations have been incredibly successful already, they're just so far beyond our comprehension of the world and consciousness that we can't meaningfully interact with them.
Perhaps the Great Filter is not a single event? Perhaps it can happen more than once and occasionally shows up as a large space rock. [0]
[0]https://en.wikipedia.org/wiki/Cretaceous%E2%80%93Paleogene_e...
[0]https://en.wikipedia.org/wiki/Cretaceous%E2%80%93Paleogene_e...
Maybe the Great Filter is global warming, or other similar planetary pollution. Once a civilization ramps up Moloch[1], the self-reinforcing self-perpetuating structures necessary to organize industry at a planetary scale, it becomes too difficult to pull back and stop it before it's too late.
[1] https://www.lesswrong.com/posts/TxcRbCYHaeL59aY7E/meditation...
[1] https://www.lesswrong.com/posts/TxcRbCYHaeL59aY7E/meditation...
Unlikely.
We're going to have a hard time dumping enough anything into the atmosphere (or causing some other kind of pollution) to kill ourselves entirely. We'd osculate around an equilibrium where we dump some pollutant into our environment to the point where our population decreases, natural processes remove it and our population increases, wash, rinse, repeat. You can see similar population and resource usage patterns in many ecosystems.
And before anyone tries to twist my words to saying global warming isn't a bad thing, that's not what I'm saying. I'm just saying that humans as a species will likely survive it.
We're going to have a hard time dumping enough anything into the atmosphere (or causing some other kind of pollution) to kill ourselves entirely. We'd osculate around an equilibrium where we dump some pollutant into our environment to the point where our population decreases, natural processes remove it and our population increases, wash, rinse, repeat. You can see similar population and resource usage patterns in many ecosystems.
And before anyone tries to twist my words to saying global warming isn't a bad thing, that's not what I'm saying. I'm just saying that humans as a species will likely survive it.
It's not species extinction that makes life undetectable, it's extinction of the civilization. For a civilization to be detectable it has to be at least at our level, or maybe a century beyond our level. If our civilization collapses it would mean that we were only detectable for a couple of centuries and then it could take millennia for us to get back to our level, especially if we've extracted all the easy to extract natural resources making it harder for our ancestors to rev back up, or if large parts of the planet become uninhabitable.
>it's extinction of the civilization. For a civilization to be detectable it has to be at least at our level,
My point is that we won't go extinct, we'll bounce back and get another try.
>especially if we've extracted all the easy to extract natural resources making
Would you rather hollow out a mountain to mine minerals or dredge through what used to be a major city? We've concentrated all sorts of useful things on earth's surface. If anything the next civilization will have it easy.
>harder for our ancestors to rev back up, or if large parts of the planet become uninhabitable.
Large parts of the planet were more or less uninhabitable. The few people who lived in the arctic and the deserts mostly just followed food/water sources. They contributed little to civilization's progress (mostly in the field of astronomy because desert nights and polar winters give you plenty of time to look at the starts) because they didn't have the spare resources to engage in those pursuits because they were too busy surviving. Progress has always come from the places that are easy to live in and therefore have resource surpluses.
My point is that we won't go extinct, we'll bounce back and get another try.
>especially if we've extracted all the easy to extract natural resources making
Would you rather hollow out a mountain to mine minerals or dredge through what used to be a major city? We've concentrated all sorts of useful things on earth's surface. If anything the next civilization will have it easy.
>harder for our ancestors to rev back up, or if large parts of the planet become uninhabitable.
Large parts of the planet were more or less uninhabitable. The few people who lived in the arctic and the deserts mostly just followed food/water sources. They contributed little to civilization's progress (mostly in the field of astronomy because desert nights and polar winters give you plenty of time to look at the starts) because they didn't have the spare resources to engage in those pursuits because they were too busy surviving. Progress has always come from the places that are easy to live in and therefore have resource surpluses.
Separate from the details of the consequences of global warming itself, more generally my hypothesis is that in order for a civilization to become aware that it is consuming too many natural resources requires a level of advanced development that can only be achieved by consuming too many resources. In other words, it might be more likely than not that when a planet produces a civilization that enters an industrial revolution it ends up burning through its natural resources in an unsustainable way and ends up collapsing. The easy access to resource surpluses that ignites the industrial revolution is also what causes them to overshoot their planet's capacity.
For us it's not just CO2 pollution that is a problem, there are many other resources that we are over-utilizing in an unsustainable way. And it seems that we are completely incapable of coordinating as a planet when the sacrifices are large. The hope of the techno-optimists is that technology will save us. It's a high-stakes bet that technology will figure it out before it's too late. Maybe the Great Filter is that when this bet is made across the universe the odds are generally in favor of losing.
For us it's not just CO2 pollution that is a problem, there are many other resources that we are over-utilizing in an unsustainable way. And it seems that we are completely incapable of coordinating as a planet when the sacrifices are large. The hope of the techno-optimists is that technology will save us. It's a high-stakes bet that technology will figure it out before it's too late. Maybe the Great Filter is that when this bet is made across the universe the odds are generally in favor of losing.
This seems like humanity’s last advanced civilization: the easy energy is all tapped out.
Maybe some other life form could have one after enough time has passed, but we can’t bootstrap ourselves a second time.
(Edit: to be clear, I’m agreeing with you.)
Maybe some other life form could have one after enough time has passed, but we can’t bootstrap ourselves a second time.
(Edit: to be clear, I’m agreeing with you.)
>This seems like humanity’s last advanced civilization: the easy energy is all tapped out.
That's probably what someone said in the middle ages when they finished deforesting Scotland.
We still have nuclear. There's an obscene amount of energy in it. It's just not attractive while we still have other "easy" options.
That's probably what someone said in the middle ages when they finished deforesting Scotland.
We still have nuclear. There's an obscene amount of energy in it. It's just not attractive while we still have other "easy" options.
If this civilization collapses, how are we going to get to the point where we can build nuclear fission reactors?
Is it that hard to enrich isotopes enough to make a steam engine that runs on radium, thorium or uranium instead of coal?
If you know that radioactive isotopes exist, it sounds like steampunk, 1850s, level tech could build a power plant, but perhaps not a bomb.
If you know that radioactive isotopes exist, it sounds like steampunk, 1850s, level tech could build a power plant, but perhaps not a bomb.
I’m not qualified to answer, but there was a bit of discussion about the idea on Reddit:
https://www.reddit.com/r/worldbuilding/comments/57peek/can_y...
https://www.reddit.com/r/worldbuilding/comments/57peek/can_y...
Interesting.
I don’t think it’s that hard to build a vessel full of warm radioactive pebbles to boil water.
Sorting ore by chemical element, and then making a fluid / gas / solution of the fuel element to sort by isotope mass in a centrifuge may or may not be doable for “blacksmith” level technology, though. Hard to say.
I don’t think it’s that hard to build a vessel full of warm radioactive pebbles to boil water.
Sorting ore by chemical element, and then making a fluid / gas / solution of the fuel element to sort by isotope mass in a centrifuge may or may not be doable for “blacksmith” level technology, though. Hard to say.
Controlled cold fusion would be even more neater as it enables you to synthesise arbitrary molecules out of just hydrogens.
That was a really interesting read. All of the examples were incredibly insightful, but the cancer one felt like the most similar to a great filter, perhaps because it can very easily be used to explain the issue abstractly.
I don't see this as likely. Global warming is not an extinction level event (for humans! for a lot of other life, it will be, although habitat loss may well play a larger role in that.)
My own speculation on the Great Filter is that any intelligent alien civilization is almost certainly a race of social predators that evolved - and thus are in competition for resources.
I worry that competition between individuals and individual states necessarily ends in the destruction of the environment on which they depend and quite likely in direct destruction in war with advanced technology.
Us humans need to find some other paradigm under which to move forward, capitalism and competition, which have brought us such amazing results to date could well also be our undoing.
My own speculation on the Great Filter is that any intelligent alien civilization is almost certainly a race of social predators that evolved - and thus are in competition for resources.
I worry that competition between individuals and individual states necessarily ends in the destruction of the environment on which they depend and quite likely in direct destruction in war with advanced technology.
Us humans need to find some other paradigm under which to move forward, capitalism and competition, which have brought us such amazing results to date could well also be our undoing.
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Why is this very bad? What is wrong with society not existing if it’s inevitable. Is dying very bad or is it an inescapable reality that isn’t good or bad? What is inherently good about life existing or spending the finite energy of the cosmos? It all comes to an end eventually. Is that bad? Can humans offer anything to the universe other than parasitism?
It seems odd that the universe would be as vast and fascinating as it is but there be no one to appreciate it.
I want humanity to reach another galaxy someday.
I want humanity to reach another galaxy someday.
One persons parasitism is another's enrichment.
Supporters of ethical hedonism hold that the enjoyment of life holds axiomatic value, and life itself is a prerequisite for enjoyment.
https://en.wikipedia.org/wiki/Hedonism
Supporters of ethical hedonism hold that the enjoyment of life holds axiomatic value, and life itself is a prerequisite for enjoyment.
https://en.wikipedia.org/wiki/Hedonism
Sure, but the Universe is going to die and we don’t seem to have any way to save it
I fail to see how the inevitable “death” of the the universe has any bearing on it being good or bad. Or life being good or bad
Yeah I am not sure where I was going with that. I think I’ve read too much “the universe is conscious” woo.
We cannot change the existence of one or more Great Filters.
Our best chance of survival is finding out about one as soon as possible.
...so the only path remains forward.
Our best chance of survival is finding out about one as soon as possible.
...so the only path remains forward.
Scary.
Give it 20yr. Between Mars and the gas giant's moons there's almost certainly some, possibly long dead, bacteria out there. Whether we share a common ancestor is anyone's guess.
Even finding dead alien bacteria would be a miracle. Time is the great constraint of finding life. It's less about where are the aliens, and more about when.
Step 1: define "life"
Great. And now let's build a telescope on the dark side of the moon!
The dark side is only dark from our perspective on earth. It still receives two weeks of sunlight a month.
If you wanted to minimize sunlight, you'd want to put a telescope at L2 [1], which is in fact where the James Webb Space Telescope will be deployed [2].
It's launch was recently pushed back from March to October of 2021 [3] (or [4] for non paywalled version)
[1] https://www.space.com/30302-lagrange-points.html
[2] https://en.wikipedia.org/wiki/James_Webb_Space_Telescope
[3] https://www.nytimes.com/2020/07/16/science/nasa-james-webb-s...
[4] https://outline.com/bsWKnf
If you wanted to minimize sunlight, you'd want to put a telescope at L2 [1], which is in fact where the James Webb Space Telescope will be deployed [2].
It's launch was recently pushed back from March to October of 2021 [3] (or [4] for non paywalled version)
[1] https://www.space.com/30302-lagrange-points.html
[2] https://en.wikipedia.org/wiki/James_Webb_Space_Telescope
[3] https://www.nytimes.com/2020/07/16/science/nasa-james-webb-s...
[4] https://outline.com/bsWKnf
Sunlight is reflected from earth too.
The dark side of the moon would be much better for a telescope array; given that the moon has no atmosphere and isn't seismically active, you could form a massive, scalable array with incredible resolution.
Is the Earth that much of a hassle if we built on the near side instead of the far side?
Perhaps for radio astronomy?
Or build it on the far side, near the poles, with a solar array just across the pole -- perhaps that way you could have solar power all year long.
Perhaps for radio astronomy?
Or build it on the far side, near the poles, with a solar array just across the pole -- perhaps that way you could have solar power all year long.
Most large telescope arrays (that I know of) are for radio astronomy, largely for geographical reasons (as far as I know).
Earth is a source of noise throughout the electromagnetic spectrum, so I think the benefits of building on the far side (eliminating Earth noise), will likely outweigh the costs (limited/more costly bandwidth).
I think a mixed array, consisting of "radio" and "light" telescopes could present very interesting possibilities, especially because you could dynamically allocate sparse sets of the array to different tasks.
All of that being said, I am an engineer (with an interest in array signal processing), not an astronomer.
Earth is a source of noise throughout the electromagnetic spectrum, so I think the benefits of building on the far side (eliminating Earth noise), will likely outweigh the costs (limited/more costly bandwidth).
I think a mixed array, consisting of "radio" and "light" telescopes could present very interesting possibilities, especially because you could dynamically allocate sparse sets of the array to different tasks.
All of that being said, I am an engineer (with an interest in array signal processing), not an astronomer.
And at L2, we'll never be able to upgrade it or even service if something were to go wrong before end of scheduled mission. Something on the moon would be much more accessible for upgrades or basic servicing missions. Even with 2 week on/2 week off schedule, it would be so useful. During those 2 weeks off, it would be charging its batteries. Never would it suffer from cloudy nights.
OTOH, a trip to the moon requires about 10x more fuel than going to L2. Although I suppose a moon telescope could synergize nicely with other lunar activities
Edit: I think I misread the table I was looking it, it's more like 2x or 3x instead of 10x, and that assumes a start from LEO
Edit: I think I misread the table I was looking it, it's more like 2x or 3x instead of 10x, and that assumes a start from LEO
There are and have been probes and observatories at L1 and L2:
https://en.wikipedia.org/wiki/List_of_objects_at_Lagrangian_...
https://en.wikipedia.org/wiki/List_of_objects_at_Lagrangian_...
I believe the dark side of the moon would be more apt for radio astronomy. The obvious reason being that the Moon is blocking interference of artificial radio signals on Earth.
The moon is interfering with radio signals? Doesn't this only happen if the moon is literally blocking line of sight? It seems like being outside of earth's atmosphere and ionosphere would be the biggest benefit for radio.
The moon is basically a giant reflector for (many bands of) radio. The reason the US government funded so many radio telescope arrays was to monitor Soviet ballistic missile tests, by looking at signals reflected off the moon.
There's still a lot of rf noise that can penetrate that far. ~3,400km of solid rock is a much better attenuator.
The other "unknown" is under what conditions can intelligent life evolve? Once you know that window, the Drake equation gets even more interesting.
The notion that we are the only intelligent species in the galaxy seems more and more unlikely.