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Research Suggests How Alien Life Could Spread Across the Galaxy
astroengine writes: As astronomical techniques become more advanced, a team of astrophysicists think they will be able to not only detect the signatures of alien life in exoplanetary atmospheres, but also track its relentless spread throughout the galaxy. The research, headed by Henry Lin of the Harvard-Smithsonian Center for Astrophysics (CfA), assumes that this feat may be possible in a generation or so and that the hypothesis of panspermia may act as the delivery system for alien biology to hop from one star system to another.
Sure, I've seen lots of panspermia videos, but shooting it all the way to another STAR SYSTEM seems a bit over the top...
Habital planets are so rare and far apart that alien life wouldn't be able to spread across the galaxy. Hell, even earth is so far away from the nearest possibly habitable planet that if we could travel 90% of the speed of light, it would take something like 10,000 years to get there. Much less a population and equipment and supplies enough to start a society.
Actually, we don't know if habitable planets are rare. We are finding a bunch and have barely look at what the universe holds. Now the traveling thing could be a problem, but maybe there are civilization on other planets that don't waste their time and resources killing each other and actually focus on science and space.
Be seeing you...
Hell, even earth is so far away from the nearest possibly habitable planet that if we could travel 90% of the speed of light, it would take something like 10,000 years to get there.
Spores are patient.
But based on what we know about the basic building blocks of life as we know it there's nothing to suggest they would have to originate from a planet that is habitable, nor that they would even all have to come from the same place to get combined somewhere that is habitable in the same way they were combined here on Earth.
we really don't know how common/rare habitable planets are let alone how far apart they are.
resistant to heat, cold, vacuum, desiccation, radiation, pressure, toxins, etc.
https://en.wikipedia.org/wiki/...
you realize they could leave earth (ejecta from a sever impact) and colonize other planets
then you think... wait a second, maybe we're here because these guys colonized earth
intellectual property law is philosophically incoherent. it is your moral duty to ignore it or sabotage it
It seems likely that mankind, and aliens who got started before us, will eventually establish permanent residences off of their home planets. In the not-so-distant future, the majority of mankind, by percentage, will live off-Earth. However, you should think of the planets as being the bottom of very deep holes, with most of them being too hot, cold, poisonous, exposed to radiation, or too much or too little pressure. The task of getting and leaving these places is risky and expensive, too. Let's just give up on the idea of colonizing Mars for the forseeable future, please! It may not always be so, but the solar system's orbital rocks are easier resources to get, and spitting up material from low-gravity objects with mass drivers. There's no point to terraforming a planet when that will take thousands of years, and no human civillization can keep a project like that, and it's cash flow, going for so long.
In short, we're just not gonna live like pale, stick-figure trolls in underground caverns on the moon or mars. Mining will be done by pulling a big bag over an asteroid and breaking it up from the outside in. Attached refining equipment will separate useful elements and chemicals. This will be mostly-automated. We'll use the tailings as concrete to build our colonies. A gigantic mirror will heat the crushed rock and sinter it into shape, like an enormous 3d printer. There is enough material to build millions of them in OUR OWN solar system, and they'll be essentially self-sustaining once they've been established. Conditions inside will be perfect for human life. It's a far better prospect than making do with low-gravity moons and poisonous planetary atmospheres. Groups of colonies might form "countries" and others will operate independently. The colonies will be built robotically, so the cost will eventually drop to the point where one might be owned by a single family or other social group.
While most colonies will participate in a humanity-wide economic and social network, a life of physical isolation and self-sufficiency will be the norm for most. We'll be in communication, but not often physically visiting other colonies. Some of these may try hurtling themselves onward to the next closest star. They'll stay in touch the whole time, they'll just be permanently out of reach from then on.
The stars DO NOT need to be sun-like, nor do they need Earth-like worlds! They just need to have exploitable resources in easy reach. Red and brown dwarfs are more plentiful than any other type, and they'll last orders of magnitude longer, too. This is probably where the majority of intelligent life will live at some point. Not to miss out on any exploitable resource, those who live around dwarf stars will push onward to practically every type of star within reach. A million years or so, and we'll have colonies throughout the galaxy, and hundreds of alien neighbors to enrich our culture and science.
Panspermia doesn't involve a bunch of Oregon Trail style settlers heading out and populating an empty world. You fire microbes, or possibly even just the precursors of life out and they start multiplying and evolving if they land somewhere they like.
I skipped the Discovery link to avoid hype and went directly to the Harvard link.
Disappointing. One expects a certain sobriety from scientists and yet something is terribly wrong here. The article is peppered with weasel words: an unusually vague 'theory'; and words like: could, might, if, potentially, would, and the ever dreadful 'assumes'. Let's hope that the actual paper will have a more solid foundation.
...omphaloskepsis often...
Now the traveling thing could be a problem, but maybe there are civilization on other planets that don't waste their time and resources killing each other and actually focus on science and space.
This. There's 7 billion of us. I'd wager less than 100 million of us are engaged in productive activities besides life-sustention, probably less than 10 million using their immense brain computation ability to do it. But this is due to war and inequality, not that the rest of the world are idiots. Not that they were born idiots. Some may have been brainwashed so thoroughly that they might as well be idiots, but that's still not necessarily a permenant condition. If everyone was given equal opportunity, and people with brilliant ideas didn't have to struggle just to survive, the average citizen struggle just not to die from all the corporate poisoning etc, then something closer to 4-5 billion of us could be doing productive stuff. Amazingly productive stuff. Stuff that probably less than 10000 people alive today could even imagine under current society.
Well put - if this was a few years ago on Slash dot it would have been modded insightful.
Were the alien's exoplanetary atmospheric escapades discovered in the Ashley Madison database?
Oh, this article isn't the hourly Ashley Madison tripe? Pardon me... I apologize. Carry on!
Beware of the Leopard.
We need to seed the universe with our sort of DNA so that by the time we get around to getting there the local cuisine is tasty and delicious even if somewhat exotic, and not yucky and disgusting or even toxic. You reap what you sew.
And if you cook it right it's mighty tasty.
Given that life had to originate somewhere, and that we know next to nothing about the distribution of life in the universe, panspermia seems to me like a solution looking for a question to be the answer of. I am bemused by the fact that some people seem to find a universe having panspermia more satisfying than one without it, just as I am bemused by people who find a universe with reincarnation more appealing than one without (if you can't remember anything about your former selves, what's the difference? - they are as good as dead.)
I don't deny panspermia could happen; my attitude is essentially 'call me when you have something that goes beyond speculation.'
When they do speak soberly and from a solid foundation, such scientists tend to be identified as Creationists, ridiculed widely and from unexpected adversaries, and forced out or ignored out of their institutions and fields.
The rest look for infinite numbers to invoke and give you their wild unprovable, untestable speculations. With their critics out of the way, all they need to do is cloak their unscientific work by speaking of it as facts and certainty.
So let me get this straight.
An AC from Slashdot poo poos a paper written by a PhD, reviewed by other PhDs and accepted into a recognized journal, in just two sentences.
I guess Dr. Lin should have just sent it to you for review first.
"everyone was given equal opportunity" How would you go about doing this for 7 billion people? I guess one solution could be to wage world wide war until there is only a few thousand people left alive and they can restart the perfect society where everyone has equal opportunities. Since the beginning of human history civilizations and societies have been created by war and then eventually destroyed by war.
Indeed, especially if kept near absolute zero within a chunk of rock and ice potentially miles across . And you don't even necessarily need spores - a single strand of RNA capable of replicating itself from naturally occurring organic molecules might be all you need to jump-start a biosphere on a new planet.
--- Most topics have many sides worth arguing, allow me to take one opposite you.
And then the SJW-callers came from breitbart. So sad.
And even the "firing" doesn't necessarily need sapient life - the impact that flung the material that formed the moon free from the Earth probably flung some pretty large chunks of material completely free from Earth, and possibly even from the Sun. There may even now be primitive cryogenically preserved microbes in the heart of some of those planetary fragments slowly coasting across the cosmos, just waiting to impact a promising new world. If the fragments are big enough the microbes could survive reentry - a few miles of shielding should be more than sufficient, and would still represent only a relatively small fragment.
If such an impact were to happen today, there's lots of Earth life that might survive the voyage. Even relatively complex animals such as the tardigrade, which has been shown to be able to survive naked exposure to space for months on end with no apparent long-term damage, and would no doubt have a far easier time of it in the middle of a big chunk of ice and rock.
--- Most topics have many sides worth arguing, allow me to take one opposite you.
And you know habitable planets are rare how?
The world's burning. Moped Jesus spotted on I50. Details at 11.
Because the right is known for its stiff upper lip...
The world's burning. Moped Jesus spotted on I50. Details at 11.
The team issue is radiation. We're talking about journies of hundreds of thousands or even millions of years. I can imagine nucleotides specifically protected by some heavy duty shielding making it (in other words big ass gene pods built by aliens), but accidental hitchhikers on meteors seems far less probable.
The world's burning. Moped Jesus spotted on I50. Details at 11.
HAL-2: "Dave, I am picking up a broadcast from this planet. It appears that there is intelligent life here."
Dave: "Can you tell me what the message says?"
HAL-2: "Just a minute; this language is unfamiliar but there is a tutorial embedded in the signal. Working... working..."
HAL-2: "The message says, roughly, 'Welcome to Scar-Oh, home of the most advanced race in the universe. Please transmit the coordinates of your home planet, and we will send a fleet out to ex-ter-mi-nate it as soon as we possibly can. Thanks for nominating yourself for a Dav Err Us Award, and have a nice day!"
That's a pretty impressive feat for a mere strand of RNA. Has anyone ever witnessed such an incident?
There's something I've never figured out about this particular theory. All life, even some sort of "patient zero" alien life, had to arise from non-organic substances somewhere, right? If it can happen once, then it should be able to happen any number of times given a set of similar conditions. Given the size of the universe, and even our own galaxy, that's like to be a *lot* of places.
As such, why would anyone think it's more plausible for a chunk of life to hitch a ride on some piece of space debris, and then survive re-entry on a coincidentally habitable planet on which it can flourish... than for life to have sprung into existence here, where obviously conditions were optimal for it (or at least life as we know it)?
I have to wonder if the enthusiasm for this theory is partially based on the admittedly exciting prospect that we could be the descendants of exotic alien lifeforms rather than some homegrown slime mold.
Irony: Agile development has too much intertia to be abandoned now.
Sorry, but it is. As much as I am a big Sci-fi fan (Bladerunner, best sci-fi movie of all time), abiogenesis is just an umbrella term for a bunch of competing crap science theories for "spontaneous generation" ... the father of that fairy tale (pun intended). Now ... you can all mod me down and/or drool out the par-for-the-course ad hominem attacks and strawmen fallacies ... or someone can frickity frackin man up and give me a plausible explanation for how life can arise from non-life.
Hate to break it you, but the formation of the Moon probably didn't seed the solar system (or anywhere else) with life from Earth. The earliest single cell life forms likely date to around 3.6 billion years ago; the Theia impact hypothesis puts the collision around 4.4 to 4.5 billion years ago (and only 30-50 million years after the Solar System even began forming). Even if both estimates are off by a couple hundred million years, there is still no overlap. Earth was an uninhabitable ball of molten rock at the time, not remotely suitable for the initial development of life remotely like ours.
$_ = "wftedskaebjgdpjgidbsmnjgcdwatb"; tr/a-z/oh, turtleneck Phrase Jar!/; print
Theeeee faggots on the bus go fuck my ass.
Fuck my ass.
Fuck my aaaass.
The faggots on the bus go fuck my ass
Because they're fuckin gaaaaaay.
snaf snarf snufle wee wonk bazoo
Fantasy. An advanced, large-brained species is highly likely to be Top Predator. Like us.
As everyone who read Larry Niven would know.
That or they fantasise about meeting women who are just like the ones here except with pointy ears, bumpy foreheads or some other prosthetics budget friendly difference. And who have the hots for nerds.
Confucius say, "Find worm in apple - bad. Find half a worm - worse."
Are we top predators? We are certainly the dominant species but that is not the same thing.
It seems like our success has been brought about by our ability to engineer the environment to our liking. After we were able to increase our population due to agriculture we started impacting on predator species partly by hunting them directly but more by crowding them out of their ideal territory.
These comments are my personal opinions and do not necessarily reflect the opinions of the other voices in my head.
There's something I've never figured out about this particular theory. All life, even some sort of "patient zero" alien life, had to arise from non-organic substances somewhere, right? If it can happen once, then it should be able to happen any number of times given a set of similar conditions. Given the size of the universe, and even our own galaxy, that's like to be a *lot* of places.
I think you are right, and probably most researchers of this subject would agree. My personal feeling is that life didn't happen because of some amazingly unlikely combination of lucky accidents, it happened because it was likely enough that it must happen almost anywhere the conditionas are right. There is a book that you might enjoy - "The Vital Question" by Nick Lane; a bit technical, but that's why I like it. According to him, prokaryotic life more or less has to happen, but he isn't so sure that eukaryotes are likely to evolve (I disagree, but that's another matter).
As such, why would anyone think it's more plausible for a chunk of life to hitch a ride on some piece of space debris, and then survive re-entry on a coincidentally habitable planet on which it can flourish... than for life to have sprung into existence here, where obviously conditions were optimal for it (or at least life as we know it)?
As far as I understand it, the current thinking is not so much that life evolved in just one place and then travelled as cells or spores to other places, but that a suprisingly large proportion of the molecules needed for life have evolved in the dustclouds around newly formed stars. Panspermia in some form could still have played a large role as well, as it isn't implausible that cells or spores could have been blasted off their home planet and survived the journey / we already know of some on our own planet that could potentially make it.
I have to wonder if the enthusiasm for this theory is partially based on the admittedly exciting prospect that we could be the descendants of exotic alien lifeforms rather than some homegrown slime mold.
Could be, but I think it also has a lot to do with the fact that until fairly recently, we didn't have any really detailed ideas about the first cells might have evolved, and there was a widespread feeling that it was a very improbable event, so the idea of life arising in only a single or a few places and then spreading out was attractive. We now know much more, and it seems like life must be widespread, maybe even universal.
That's just an excuse, a very very very lame one.
I take it you haven't met average people, have you? I'll bet you're surrounded by upper-class Ivy League (or wished they had gone to an Ivy) intelligent people like yourself all day long, and have used that great intellect to project those characteristics onto the rest of humanity. Why don't you actually get out there and talk to some of them? You'd be horrified, and withdraw into a gated community like so many of your fellow travelers have already done.
Just think of how stupid the average person is. And half of 'em are stupider than that!
-- George Carlin
Shutting down free speech with violence isn't fighting fascism. It IS fascism!
While the vastness of time and space make it a near certainty that there is/was/will be life in thousands or even millions of places, at the same time it's rare enough that makes it very likely that no life will ever come into contact with any other life. Maybe there was life just a few light years away from us... a billion years ago, and that never made it to a multi-cellular level. Maybe at this very moment there's an intergalactic civilization a hundred billion light years away that will completely collapse before we could even notice them (plus, all life here will probably have ceased by that point as well).
robots, automation, industrial-level 3-d printing, and many more sustainable energy generation systems. It's actually not too far outside our current capabilities. It's just that the 1% will never allow everyone else to come up to their level, or allow themselves down here in the dirt with the rest of us.
yeah, I don't know if their idea of a three meter rock (mentioned in this article that is linked inside TFA) is thick enough to stop radiation once outside the heliosphere. But the second article is discussing intra-solar transfers, not between systems. I have no idea what level of shielding would be required to survive millions / billions of years of traveling through interstellar space.
He should win the Nobel for the name alone! :-)
And if frogs had wings they wouldn't bump their asses on lily-pads.
We need to stop warring and have those people do something useful instead
And how do you suppose we do that? We must war so there is so few people left, then those left can do something useful!
*facepalm*
It doesn't have to be something as large as that. Much smaller impacts throw up material from rocky planets that can seed the solar system. Escaping the sun would be a bit harder, but it could happen via occasional very large impacts, or comets being seeded by small impacts and then ejected from the solar system.
Actually, we don't know if habitable planets are rare.
It depends on what you mean by "rare". Habitable planets that are hundreds, thousands, or millions of light years apart are rare on the scale of living organisms.
Curious, are you the same APK who was complaining earlier that someone who pointed out that your writing style resembles geocities (which it really, really does) was making an "ad hominem" attack on you (comment here for reference)?
I ask because it looks from here as if you are confused or misinformed about what such an attack is: It's not merely an unflattering observation of facts as in the case of the "geocities" observation, but it is rather attacks such as "You unbelievable blowhard bullshitting fuckwad loser" quoted above.
Either ad hominem attacks are bad, or they aren't; you can't have it both ways. (Spoiler alert: From most perspectives they are "bad".)
Curious, are you the same APK who was erroneously complaining earlier that someone who pointed out that your writing style resembles geocities (which it does, by the way) was making an "ad hominem" attack on you (comment here for reference)?
I ask because it looks from here as if you are confused or misinformed about what such an attack is: It's not merely an unflattering observation of facts as in the case of the "geocities" observation, but it is rather attacks such as "blowhard bigmouth done zero loser" quoted above.
Either ad hominem attacks are bad, or they aren't; you can't have it both ways. (Spoiler alert: From most perspectives they are "bad".)
Again, I (we) get that you are high on your windows-only tool that installs somebody else's custom hosts file in place of the default one, but you might win more believers by being less of a geocities-writing-style asshat. I am sure you are a nice guy; I am not criticizing you. This is genuinely friendly advice. When I was younger and sometimes acted like this, I now wish someone had give me the same advice.
You do realize that we haven't even found life on a second planet yet, don't you? This is extrapolation at its speculative best, people. Get back to us when you fine life in one other location in the galaxy...
Ice. Water is very good at stopping radiation. There's lots of ice in comets. One RNA strand, encased in ice in a comet, ejected from a solar system.
Chances are tiny. Number of trials is huge. Time span is extreme. Need more data.
We don't have a state-run media we have a media-run state.
The 1% probably includes a lot of people who have no say in anything that goes on.
This is the problem of big numbers. You're multiplying a really big number (number of solar systems) times a really big number (time) times a number of unknown smallness (chances of life emerging from inorganic materials). We only know it's happened once. We haven't seen it anywhere else in the universe. We've tried our hardest and never seen it in a lab. So we have no idea what order of magnitude that chance is. A few orders of magnitude in one direction and there's life everywhere. A few orders of magnitude in the other direction and there's life in but a handful places in the universe. Maybe even only here.
We need more data to help pin down what order of magnitude that really small number is. One thing that would help with that, though, would be what these researchers propose to look for. Once we can detect signs of life on an exoplanet (like the presence of oxygen in the atmosphere...a very likely sign of organic processes under way, because oxygen does not stay free for long), how uniformly is it distributed in the galaxy?
If life is likely to arise, like your hunch, then life in the galaxy should look pretty uniform. It's everywhere. But if instead it's clumpy (or more likely smeared as stars move relative to each other) then that indicates life is very rare, and spreads instead by panspermia.
Uniform distribution of life in the galaxy: life is likely to arise, and may or may not spread via panspermia, too.
Clumpy/smeary distribution of life in the galaxy: life is unlikely to arise, but likely to spread via panspermia.
We don't have a state-run media we have a media-run state.
I've always figured it was both simple life developing here, then complex life hitching a ride and spicing things up when it landed. http://www.livescience.com/280...
Actually, we don't know if habitable planets are rare. We are finding a bunch and have barely look at what the universe holds. Now the traveling thing could be a problem, but maybe there are civilization on other planets that don't waste their time and resources killing each other and actually focus on science and space.
That seems improbable. We only developed minds as advanced as we have now because of working our way up the chain to be apex predators then not stopping and further refining our intellect by fighting eachother for what is likely hundreds of thousands if not millions of years. The only known mechanism to produce intellect is intensive intraspecies warfare.
How do you get the hundred million engaged in productive activities besides sustaining life? Most people in the US do not work in agriculture or the clothing or construction industries, and that's pretty much what you need to sustain life. Add in Europe, and you're clearly talking hundreds of millions. Do you count engineers designing new machines and prototyping them as unproductive or life-sustaining? I'm in the support structure for that activity.
Realistically, lots of the seven billion of us do not have seriously above average intelligence and creativity. There are a lot of people I know who couldn't do brilliant things no matter what the opportunities. Shall we look at the number of people we can draw on who have the opportunity to shine, and that's well in excess of a hundred million people in the US alone. There are millions of people in the US with Ph.D.s. I suspect that the percentage of the population that has opportunities to become a scientist or artist has never been higher, and that there are billions of people with such opportunity. We can and should do better, but there really isn't that much war anymore, and while the number of people who struggle to survive as gone up, as a ratio I suspect it's smaller than ever before.
"When you have eliminated the unacceptable, whatever is left, however improbable, must be the truthiness" - Holmes
What are your feelings on HOSTS files? APK
what makes me laugh MOST about you?
Something tells me someone as sad and pathetic as APK doesn't do a lot of laughing.
Organics are simply what our form of life is made of; it doesn't imply it was made BY something living. It's just a class of molecules. The universe is filled with organic matter which is not living.
And who have the hots for nerds.
Being aliens doesn't make them any more desperate than earth women.
Also, the statistical sample of exoplanets that have been found is biased by the types of stars, mainy red dwarfs, that we've been looking at in order to find exoplanets. Given how little we know about planet and star formation, the error imposed by this bias could be considerable.
"We need to stop warring " Since the dawn of time there has always been at least one war raging somewhere on the planet. Every border on the planet has been drawn in blood. Power and influence has been built on top of mounds of corpses. There are currently numerous wars raging all over the world providing the blood needed to redraw existing borders while also increasing the body count. Pleas for love and understanding are just empty words no matter how loud you shout them. Instead of solving the problems in the world today we only want to find someone to blame and thinking assigning blame translates into actions to correct the problem.
Proper use of the scientific method may prove or disprove a hypothesis.
A widely publicized hypothesis might cause mass hysteria while being neither proven nor disproven.
Could "A hypothesis of panspermia" "act as the delivery system for alien biology to hop from one star system to another" ?
NO. Any "delivery system" requires instantiation of a mechanism, which might follow from a provable hypothesis.
Hitchhikers *in* asteroids, not on. I agree any on the outer surface would be unlikely to last on an interstellar journey, but an asteroid hundreds of feet across is pretty tiny really,, and offers *far* more radiation shielding than we have on the surface of the Earth - the atmosphere offers only about 10-15 feet of rock equivalent, and the magnetosphere only protects us from charged particles that wouldn't make it far through solid rock anyway.
--- Most topics have many sides worth arguing, allow me to take one opposite you.
(Some) RNA self-replicates from amino acids all the time, and is one of our current best guesses for the earliest forms of proto-life - it's can forma an amazingly versatile range of nanomachines. The question is whether it's more likely that a self-replicating strand forms spontaneously on a hospitable world or gets seeded from elsewhere. After that it's just a matter of evolution.
--- Most topics have many sides worth arguing, allow me to take one opposite you.
While OOL (Origin Of Life) is by no means a settled question on Earth, we do at least have good evidence of what happened here. Otherwise, being able to determine that life originated in a cluster which got destroyed 3 billion years ago by a GRB is unlikely to leave much tangible evidence.
If it can happen anywhere, it could happen repeatedly. And so multiple civilisations is my bet, and they just learned to keep quiet around the Primitives.
Everyone is dead, or elsewhere remains on the list of possibilities.
Birds are not dinosaur descendants;birds are dinosaurs, for all useful meanings of "birds", "are" and "dinosaurs"
Do you listen to the nonsense you spew. There are 7 billion people on earth. A feat that has taken 3 or so million years to accomplish and at any point in time it could well have ended badly and you spout out corporate poisoning and yet we as a species flourish. Then you throw in a dash of SJW with your 'given opportunity' and you still don't answer the or come close as to why panspermia works or should given it's statistical impossibilities (your words) and then you leap to the idea that you believe this is the way it probably happened, so you devolved your idea down to simple faith. You're no better than a religious believer.
That alone makes us the top on this planet. Until any other species cancel what we've done for good or for ill, then we are apex.
For the sake of clarity I'm going to split this post into two - one pro-planet, and one for habitat discussions:
I'm not fixated on living on planets - I'm saying they have a lot of their own advantages which make them desirable locations TOO. Basically:
Planet advantages:
- serious radiation and impact protection
- real gravity
- abundant resources (almost all mass close enough to our star to not be effectively interstellar)
- a large enough ecosystem to absorb large disruptions without lasting damage (at least in the case of Earth, and any planets we decide are worth spending a few thousand years terraforming)
Disadvantages:
- Deep gravity well requiring surface-to-orbit infrastructure for easy access to space
- most resources probably substantially more difficult to access than from asteroids (asteroid ease suspected but not yet known with certainty)
- long-term adaptability of humans to different surface gravity is currently completely unknown
I'll grant you that if we discover that humans can only thrive in a narrow range of gravities we'll have a problem. In principle there's no reason that centrifuge-habitats couldn't be constructed on lower-G worlds to make up the difference, but they would almost certainly be more problematic than doing so without gravity or air resistance. I'll repeat though that from the very limited data we've accumulated, there's no particular reason to assume that lower gravity would present a major problem - the microgravity problems discovered to date seem to all be related to the total absence of properties that would only be moderately impacted by even relatively large departures from 1G. And there's no particular reason to suspect that human adaptability is so poor - for example most humans can adapt just fine to atmospheric pressures between 0.5atm and 2atm, despite the fact that most gene-lines have never been exposed to anything close to those extremes. Infant mortality might be high until greater adaptability evolved, or there might be centrifugal "pregnancy districts" to allow infants and expectant mothers to remain at 1G during any critical developmental periods. Or, perhaps the best option, we could breed such adaptability into mice or other animals and then transfer the relevant genes into human colonists. Modifying ourselves to better fit the environment would after all be far more expedient than adapting the environment to fit us.
I like your sintered ceramic honeycombs, can you point me to any information about research into the relevant properties of such materials? I would suspect though that any such material could be made far stronger in compression than tension, and compression has the advantage that micro-fractures are less likely to lead to sudden catastrophic failures. You could use the same basic material to construct arched tunnels and domes for underground habitats at a substantial reliability advantage. And you would probably want to do so anyway even for your honeycombed spinning asteroid - if you've got 1G of pseudogravity then those habitat modules will need to be able support the "weight" of anything above them, at least as a safety measure in case the module directly overhead loses tensile support. And if you assume a large city-sized structure at 1G psuedogravity, there's no reason you couldn't do substantially the same thing building on a planet - there's no need to leave rock untouched if everything above you is engineered to distribute the weight evenly. The deeper you go the greater the pressure from above, and at some point you'll likely need more walls than rooms to support the load, but even if you only covered the planet with a mega-habitat few dozen miles deep you'd likely have more habitat than available from all the asteroids in the inner system. And if your large-scale engineering is sufficient to distribute the load laterally around the planet instead of only vertically - well then you can keep going deeper until it gets too hot for comfort and/or structural stability.
--- Most topics have many sides worth arguing, allow me to take one opposite you.
I have to agree with you about giant windows being a bad idea. Observation domes, etc. on the outer surface would certainly have their place, who wouldn't want to look down through the transparent floor and see the stars spinning past beneath them? But such chambers should be easy to isolate from the main habitat in case of the inevitable impacts and radiation surges. Giant windows letting you see stars overhead may make for good science fiction, but I doubt many people would want a scant sheet of "glass", no matter how sturdy, being the only thing standing between their children and explosive decompression.
I'm less convinced that such huge open environments are a good idea, at least as the primary habitat. Personally I'd certainly enjoy having such a "tube of air" available for "outdoorsy" activities, but I would suspect the bulk of the actual habitat would actually be within the "ground". Even psychologically, it might be preferable to have an expansive painted (OLED screen?) sky several stories overhead rather than seeing the world curling up over you. That would also allow for multiple floors with very different gravity - I'm sure "low G" floors would have numerous recreational, industrial, and rehabilitative applications. Such interior floors could even be potentially constructed from structurally-stabilized high tensile strength fabric, adding minimal mass while providing not only expansive low-G surfaces, but also air baffles to prevent Coriolis storms, and to slow atmosphere loss in case the outer hull were punctured.
As for lighting - I like the light-pipe idea, be it glass tubes or mirrored pipes leading to windows overlooking large interior areas. I think I would avoid vacuum though, too much trouble. I'd lean towards slightly over-pressured clean-room grade air, so that the lighting tubes need not be completely airtight to avoid dust contamination. Maybe even pure nitrogen or carbon dioxide to avoid oxidation issues as well, while also discouraging adventurous "explorers". Combined with airflow monitors it would even make it relatively easy to locate breaks in the tube without requiring manual inspections. With advances in photovoltaics and electric lighting though, it might well make more sense to stick to artificial lighting. And of course for trans-Neptunian habitats fusion-driven electric lighting is almost a forgone conclusion.
--- Most topics have many sides worth arguing, allow me to take one opposite you.