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mutleyeng
2012-May-15, 08:49 PM
this is just for fun speculation. But lets try and keep realistic without bending laws of physics. No mass migration to other star systems.

People seem to think that humanity in the solar system is doomed. The sun will swell, perhaps engulf the earth, and shrivel to a white dwarf and that will be an end to it.

But would it.
Why would humanity not be capable of surviving this.

How long can we keep Earth habitable. As the sun heats up, isnt it reasonable to think we would have the ability to control the suns energy that reaches out atmosphere? perhaps a vast roller blind between us and the sun? If i remember right, we have max a billion yrs before we have either protected the planet, or it will be baked.
so then perhaps we can get a few more billion yrs untill the sun enters its red giant stage.
I seem to recall hearing that the earth may migrate its orbit towards the outer sytem, but it is not certain if it would be engulfed or not.
Its migration out could be amplified artificially by hurling asteroids past it giving it an extra tug. Maybe the earth as a gravity chunk of rock could be saved? it is unlikely that a nice green planet with breathable air would survive, but hey, domes are cool right?
If the Earth cannot be saved, i guess you would want to find the largest chuck of rock you could in the outter system to give as close to 1g as possible. it would be a good idea to have atmospheric pressure too id suppose.
As the sun blows off its shell, we are left with a weak white dwarf, but there will still be plenty of resources around... assuming that we can get the hang of fusion power generation, we can heat and light out cosy domes.
and then theres andromeda. We will be in the mix, but we probably wouldnt really notice much in out quet little system.
i dont really see a good reason why our ancestors wont still be around in 6 billion yrs.
but maybe im missing something...quite likely

JohnBStone
2012-May-16, 08:27 AM
this is just for fun speculation. But lets try and keep realistic without bending laws of physics. No mass migration to other star systems.
How does mass migration bend the laws of physics?


People seem to think that humanity in the solar system is doomed.
"Humanity" is doomed. In a billion years intelligent life will likely be as different from what we are now as we are different now from what we were a billion years ago - ie single celled bacteria. Would you call the bacteria we originated from "humanity"?

To answer the question you have to have some inkling of our ancestors will be like in a billion years? What will be our physical form and our biological needs (if any)? How long will the lifespan be? Will we be effective immortals? With backups? ;-) What will be our effective IQ?

Some thoughts:

As the Sun heats up the rate of atmosphere loss will increase - we might want to encourage this. Less atmosphere = less greenhouse effect.

Any engineering projects we could conceive of as being practical with current tech transferred to space are pretty much baseline assumptions for a billion years out.

Space based heat shields, increasing albedo on land on a planet wide scale, large domed arcologies on land, all seem like baseline tech assumptions for the short view - thousands of years not millions.

I speculate we can survive the heating sun with currently perceivable solutions given a much shorter timescale than a billion years.

ravens_cry
2012-May-16, 10:21 AM
While it is a fairly common trope, story telling device, to have humanity survive for billions of years in some form or the other, the sheer scale is just beyond comprehension. Even a million years is magnitudes older than written human history, and a billion years is a thousand times that.

mutleyeng
2012-May-16, 11:42 AM
oh you are both right of course,
Im sure technology will play a part it what humans become - but my wild speculation would be that technology would also be used to maintain, more or less, our current form. Lifetime extention certainly.
If you look back on the history of life on earth it is absurd to think anything like us would be around in billions of years - but that was without technology. This is now a whole new ball game.
The big issue for humanity i see will be how the technology to extend life will have serious repercussions on population.
The same problem, population, will become an issue when trying to deal with the changing state of the sun.

and yes, engineering solutions will need to be in place within millions of yrs time frame for controling climate.

eburacum45
2012-May-16, 03:34 PM
The period immediately after the Sun leaves the Main Sequence would be a very dangerous time. There are flashes, and pulses, and two different red giant phases;
http://www.astronomy.ohio-state.edu/~pogge/Ast162/Unit6/futuresun.html

When the sun is a red giant, the habitable zone would be out around Saturn, if I recall correctly. Perhaps we could all live on Titan for a while.

Later when the Sun is a white dwarf, there would be a long period when it is about as cool as the Sun; the habitable zone would be less than 0.02 AU out, but it could last for more than three gigayears.
http://arxiv.org/abs/1103.2791

So it could be worth the effort to survive the red giant phase, in order to take advantage of the long cooling down period.

Eventually we would need to move off to a red dwarf - but there are plenty of those, and they'll last a trillion years.

Swift
2012-May-16, 07:47 PM
If you look back on the history of life on earth it is absurd to think anything like us would be around in billions of years - but that was without technology. This is now a whole new ball game.
BAUT has had these discussions before, and we are all just speculating, but I think it is not possible to know if technology will keep intelligent beings with any resemblance to current humans around for a billion years. And if somehow our decendents are still around, and are intelligent and users of technology, I don't think they will closely resemble us. But if all that does happen, or there is another intelligent, technological race still around (I wish the intelligent cockroaches all the best), I suspect they will find a way to survive, whether it involves protecting the Earth, moving it, or moving around the solar system.

eburacum45
2012-May-16, 08:29 PM
I should point out that moving the Earth into a significantly different orbit would require much more energy than moving the population of the planet to a nearby star.

mutleyeng
2012-May-16, 09:08 PM
but you need somewhere to go - and its not just the total energy required, but the logistics of achieving it.
in this highly speculative scenario - i would think moving around the solar system would be easier than trying to migrate to another star.
I understand the argument of evolution, but i find i am unable to concieve of why humanoid descendants wouldnt be capable of surviving billions of years. I think the biggest unknown is more how they would think compared to us than how they would look compared to us.

Selfsim
2012-May-16, 11:28 PM
The idea that we can control the humanoid-life sustaining parameters of the external environment, to within the tolerances necessary for survival, strongly shapes our present day visions of the future, and may not be valid.

The idea that biological evolution is solely dependent on these external environments, is also not valid.

A more interesting conversation would be about how one proposes to constrain such prior perceptions, in order to visualise the physical reality of the future.

ravens_cry
2012-May-17, 12:42 AM
It wasn't set quite this far in the future, but a webcomic idea I had, among other things, aliens who liked pretend to be humans as a kind of mourning/homage/worship/cosplay.
Some changed their physical form while others their psychology, with varying degrees of accuracy for both.

eburacum45
2012-May-17, 08:07 AM
The idea that we can control the humanoid-life sustaining parameters of the external environment, to within the tolerances necessary for survival, strongly shapes our present day visions of the future, and may not be valid.

The idea that biological evolution is solely dependent on these external environments, is also not valid.

A more interesting conversation would be about how one proposes to constrain such prior perceptions, in order to visualise the physical reality of the future.I am not entirely sure I understand you, but if you mean that it may prove difficult or impossible to sustain humans in their present form on other worlds and at other times in the deep future, I am sure you are correct. Both natural and artificial evolution will probably change humanity significantly within a few thousand years, let alone a few billion.

One remote but non-zero possibility is that the civilisations of the deep future retain data banks which contain information about our current era; such things as digitised human DNA, literature of many kinds, even media files, could be preserved for extremely long periods of time with very little data loss (thanks to error-checking systems). A far-future civilisation could reconstitute humans and our culture (after a fashion), and allow representatives of our race experience the long slow cooling off of our Sun.

Whether they would ever actually want to do that is a completely different question.

mutleyeng
2012-May-17, 02:22 PM
i reckon if the horseshoe crab can be around for almost half a billion years virtually unchanged, humanoids with technology could do the same....the unknown is whether they would wish to change what they are.
humanoid means a head atop of a torso with two arms and 2 legs - what uncontrolable evolutionary pressure would change this

Swift
2012-May-17, 02:33 PM
i reckon if the horseshoe crab can be around for almost half a billion years virtually unchanged, humanoids with technology could do the same....the unknown is whether they would wish to change what they are.
But if you compare the number of species that have survived for such a considerable length of time, versus those that didn't, the odds are against that happening. According to this presentation from San Jose State University (http://www.sjsu.edu/depts/EnvStudies/syllabi/summer2010/envs10/Lect6a.Evolution%20of%20Species.pdf), the average time a species spends on Earth is 1 to 10 million years.

I am just speculating, but I am unconvinced that technology changes that by multiple orders of magnitude. One might argue, by giving us tools that literally can reshape or destroy the environment on a global scale, or give us multiple other means to kill ourselves off, that technology might actually shorten the length of time humans spend on Earth. It certainly is a toss-up, IMO.

mutleyeng
2012-May-17, 02:38 PM
but surely those statistics are a consequence of enviromental changes and natural disaster, which is precisely what technology can isolate you from

ravens_cry
2012-May-17, 03:53 PM
Even if we last that long, whose to say we will not decide to put our own hand to the tiller and make funky changes at whim?
Some might decide to stay resembling baseline humans in appearance, perhaps even the majority, but even then that doesn't mean they are the same 'under the hood'.

mutleyeng
2012-May-17, 04:21 PM
i can quite easily see us diverging into different (multiple) species - they will always fall on the hominans tree though - i think thats the point.

Swift
2012-May-17, 04:56 PM
but surely those statistics are a consequence of enviromental changes and natural disaster, which is precisely what technology can isolate you from
Can it? Can technology completely isolate a species from environmental change and natural disaster? You take that as a given, I do not, particularly over the time span of a billion years. I will grant you that it probably helps to isolate you from such changes, but I doubt it gives complete isolation, and I also think it may introduce many new risks (nuclear weapons, biological warfare agents, climatic and environmental changes, just to name the current risks.).

mutleyeng
2012-May-17, 06:04 PM
i dont mean to say it is a given, just that it is not too far fetched to think that it could
we may not be able to stop yellowstone from erupting, but we should be able to mitigate the effects on a population.
Im sure there have been populations of horseshoe crabs that were wiped out from a particular location.
when we have computers capable of modeling climate, we can concievably think about controling it
our lineage is at risk for the period we are all stuck in one place, but by the time that changes, the risk of self annihilation should be significantly reduced too.

ravens_cry
2012-May-17, 06:26 PM
I know this is completely off topic, and I make my own fair share of mistakes, but is there a reason you don't use capital letters?

mutleyeng
2012-May-17, 06:32 PM
its called, being lazy

in my defense, i never use text speak, so i think that mitigates my crime to some degree

Swift
2012-May-17, 07:04 PM
its called, being lazy

in my defense, i never use text speak, so i think that mitigates my crime to some degree
And here I thought you were just a big fan of archy (http://en.wikipedia.org/wiki/Archy_and_Mehitabel).

Swift
2012-May-17, 07:13 PM
i dont mean to say it is a given, just that it is not too far fetched to think that it could
Back, sort of, on topic.

No, it is not too far fetched.

A little off topic... I think I get a little riled when people suggest that somehow, for example - because of technology, that humans are divorced from nature and the natural world, in this case, environmental change and natural disasters. I don't think it is true, and I think it a very dangerous attitude, both for individuals and for humans as a species. If we think we are somehow insulated from such things, that we leave ourselves open to being hurt by them. Look at any number of natural or enviornmental disasters for examples.

But I don't want to derail the discussion too much.

Romanus
2012-May-19, 03:13 PM
The energy spent on saving the Earth from the Sun could be better spent moving humans (and perhaps the biosphere itself) to another world altogether.

publiusr
2012-May-19, 05:50 PM
Something to think about. Yes in billions of years intelligent life won't resemble anything we know--but what if--on a lark, they get bored, and bring back us back as we are now trying with the mammoth? That handful of throwbacks will be in for a nasty shock.

djellison
2012-May-19, 06:00 PM
Why would they be in for a shock?

Some new-born human in a billion years will not be born with any memory of today or any expectations for what the world should be like.

That new world that WOULD be a shock to US...will just be normality to a human born at that time.

publiusr
2012-May-19, 06:07 PM
Being us earlier models, they will have the evolutionary programming that looks at anything different as a threat. They will be less prepared than us. There are billions of us, so we would cope well enough if facing ET. But imagine waking up with a handful of brothers--and every other entity you see is a machine. Talk about the Matrix! Now maybe they would take that into consideration--that and uncanny valley--and appear to us as did the mecha from the more friendly movie A.I.

But what if we were just something to be stuck into a cage? Now for Magnus, the Robot fighter...

Paul Wally
2012-May-19, 06:08 PM
I'm just wondering: How hot will the solar plasma be when the Earth is immersed in it? Could the Earth as a planet (not biosphere) actually survive the red giant phase? Wouldn't there be some kind a drag slowing the Earth down to a lower orbit?

Maybe there is some possibility of living deep underground. Will there still be a liquid mantle by then?

I think these are some of the considerations for technology a couple of billion years into the future. Nuclear fusion technology attempts to magnetically contain the equivalent of solar plasma, but what about doing the opposite: magnetic shielding of plasma from a closed region of space or is that impossible? But is it really worth trying to overcome all these difficulties rather than simply developing interstellar migration capability within a very generous time-frame?

publiusr
2012-May-19, 06:17 PM
A post life Earth would be a heck of a thing to mine for all its worth.

djellison
2012-May-19, 06:25 PM
Again - you're talking nonsense. Does a baby born in a $10M New York apartment go 'Ooo -that's luck' compared to a baby born into poverty and almost instant starvation in a tent in an impoverished nation in sub-saharan Africa going 'Bummer- this sucks'

No.

publiusr
2012-May-19, 06:35 PM
I really don't see how you can believe that. How many commercials for childrens aid have we seen of children with distended bellies? You really think they don't know they're in a horrible shape? How many children have been born in areas where the land is flat and cold--where howling winds can bring one almost to madness as in the plains? Yes Depression era babies didn't know they were poor--but that only goes to a point.

mutleyeng
2012-May-19, 07:01 PM
I'm just wondering: How hot will the solar plasma be when the Earth is immersed in it? Could the Earth as a planet (not biosphere) actually survive the red giant phase? Wouldn't there be some kind a drag slowing the Earth down to a lower orbit?

Maybe there is some possibility of living deep underground. Will there still be a liquid mantle by then?

I think these are some of the considerations for technology a couple of billion years into the future. Nuclear fusion technology attempts to magnetically contain the equivalent of solar plasma, but what about doing the opposite: magnetic shielding of plasma from a closed region of space or is that impossible? But is it really worth trying to overcome all these difficulties rather than simply developing interstellar migration capability within a very generous time-frame?

so far as i can tell, it is open to debate whether the Earth will survive. Ive read many sources that suggest Earth could move to nearly 1AU further out during the red giant phase ..(check out first link in post#5 that Eburacum45 provided)
I figure that if humanoids are around then, and they kinda like 1g, then the earth under protective shields of some kind would be a prefered option to generation ships that may take thousands of years to get to somewhere not much better than they left (and lets not forget how dangerous it is to travel at high speeds through the cosmos)...but of course its just wild speculation. But you get the spirit of it by asking those questions.
how long the Earth will remain a geologically active planet is a question ive never seen an answer to. I guess people arnt thinking about it from a white dwarf era system point of view so the question appears moot. Folk are so short sighted

Swift
2012-May-20, 02:58 AM
Again - you're talking nonsense. Does a baby born in a $10M New York apartment go 'Ooo -that's luck' compared to a baby born into poverty and almost instant starvation in a tent in an impoverished nation in sub-saharan Africa going 'Bummer- this sucks'

No.

I really don't see how you can believe that. How many commercials for childrens aid have we seen of children with distended bellies? You really think they don't know they're in a horrible shape? How many children have been born in areas where the land is flat and cold--where howling winds can bring one almost to madness as in the plains? Yes Depression era babies didn't know they were poor--but that only goes to a point.
You two are completely off topic and are seriously derailing the thread (and getting into your usual head-butting modes). Knock it off. If you have no constructive comments for this thread, then don't post in it.

publiusr
2012-May-20, 08:09 PM
Initially my thoughts were what the reactions of humans would be in a white dwarf era. Now if we evolved with our star djellison would be correct, in that the adaptation to this future would be gradual. Another posted assumed that there would be no humans we would recognize in the white dwarf era. But if modern humans were broght back through cloning--we might not cope as well without gradual adaptation:

Take thse artists for example:
http://en.wikipedia.org/wiki/Ron_Mueck
http://www.wired.com/magazine/2011/11/pl_art_evanpenny/?pid=7638

Even when expecting the hypereal--they still strike one as odd. So as far as humans in a white dwarf era--we would not do so well if suddenly thrust into said situation. Any descendants? That remains to be seen...

mutleyeng
2012-May-20, 08:32 PM
i dont see any reason to think they would be "spooked out" by what they see. It is true to say there may be some physical issues with such things as daylight, and maybe other unforseen enviroment changes.
To my mind, i think it most likely humanity will evolve into distinct species. A speration may occure with colonies leaving Earth. I still feel those that remain will essentially be humanoid. What the others do i cant imagine.
But as i say, they will all still be hominans no matter what they look like

Noclevername
2012-May-22, 10:58 PM
Returning long-flight near-lightspeed starships might be a source of "old school" humans, kept evolutionarily "young" by relativity. It's just the twin paradox applied to a species.

Noclevername
2012-May-24, 12:02 AM
As far as the difficulty of moving planets vs. moving populations is concerned, moving a single object would be simpler than gathering up X billions of beings and getting them all to move elsewhere. (Note that we're talking about depopulation of an entire planet, possibly several with colonization and terraforming, and building fleets of perhaps millions of starships. Compared to that, building a fusion candle on a gas giant to gravitationally billiard-ball a few planets seems like a relatively easy task.)

A third option would be to magnetically strip hydrogen off the Sun, slowly converting it into a red dwarf star with a trillion-year lifespan. The hydrogen removed would provide more than enough energy to move Earth or to keep it habitable at a greater distance, and the expansion and white-dwarf phase could be avoided altogether.

Van Rijn
2012-May-24, 05:35 AM
The fusion candle idea was a fun idea for a story, but has anyone actually run the numbers? Is it even physically plausible, given the amount of energy available in hydrogen and the mass of the planets to be moved? Anyway, if you have controlled fusion on that scale that can fuse simple hydrogen (protium, not deuterium), and if you can move that much mass (planets!) around, starships would be pretty easy. You could even have just one worldship, with a trivial mass compared to a planet, and carrying along frozen hydrogen balls for fuel. Something with the mass of a good sized asteroid could have a population of billions and given the timescales discussed here, it doesn't have to move very fast. So what if it takes 50,000 years to reach another star?

Hlafordlaes
2012-May-24, 01:07 PM
Every time I think of the long run scenarios, I am more convinced we will eventually have to switch from adapting environments for us to adapting ourselves for them (usual suspects like radiation resistance and organ fixation/fluid circulation in low grav).

If and only if the mind does become truly mapable and something akin to copiable, then I'd vote for the Data-analogue as part of our non-organic future.

mutleyeng
2012-May-24, 01:26 PM
well it be cool if it was... at least we can reasonably consider sending data at the speed of light.
I dont know if you will ever be able to download consciousness though, thats anyones guess.
The whole singularity thing is certainly an interesting milestone that could reach us within a lifetime...,maybe

bren10
2012-May-26, 01:18 AM
If the human race survives that far into the future, we will have created technology that we can't begin to fathom in today's age. What would a person who lived just 1000 years ago think if he saw the world today? Now add an additional 1,000,000,000 years onto that.

I would also expect the human race to have colonized new worlds. Our population right now is 6.8 billion right now. I'd think the total population of our ancestors would be well into the quadrillions by that point. We would likely have colonized many new worlds, and since each world would basically be an island, each inhabited world would likely evolve into it's own unique species of human.

If we don't colonize new worlds, I see no way we survive that far into the future. The world has a limited amount of resources, and we use exponentially more resources as time progresses. If we can't figure out a way to get off of this planet, we will be doomed at some point.

I would expect technologies that seem absurd by today's standards. And if we have colonized new worlds, we will have an enormous population spanning several star systems. With such an enormous amount of resources, I could foresee civilizations using some sort of technology to collect matter in the galaxy and actually create their own custom made solar systems. Civilizations could create a sun like star, place a large brown dwarf out in the outer regions of the system and place a dyson sphere around the brown dwarf to collect energy while the populations live on custom made planets in the habitable zone around the star.

This sounds absurd, but if we survive for another billion years, technology that we can't even comprehend will be millions of years out of date!

eburacum45
2012-May-26, 11:06 AM
The fusion candle idea was a fun idea for a story, but has anyone actually run the numbers? Is it even physically plausible, given the amount of energy available in hydrogen and the mass of the planets to be moved? The 'fusion candle' idea for moving the Earth is a ferociously inefficient way of doing the job. If I recall corectly, the idea is you don't move the Earth directly- instead you use the hydrogen atmosphere of a gas giant (Uranus or Neptune) to move that planet, which is then employed in a game of cosmic billiards to alter the Earth's orbit.

Moving the massive bulk of a gas giant would require vastly more energy than just moving the Earth (which could conceivably be acheived by mass-stream technology)
http://paulbirch.net/MoveAPlanet.pdf

...and both would require much more energy than transporting the entire population elsewhere in slow generation ships; if these vessels are only accelerated just enough to escape the solar system, they would be the most efficient way of getting people from star to star. Except for the fact that the journey would take tens of thousands of years, of course.

mutleyeng
2012-May-26, 11:28 AM
hmmm,
i cant see that for some reason.
the easiest way would seem to me to be to eb and flow from the star as required.
If your going to build ships to carry whole populations, you might just as well create an artificial planet and stay put, which would be safer and easier to project manage, or find existing platforms to use as staging posts thoughtout the sytem.
The effort to protect our planet from an aging star will have to start fairly soon..within 1000s of years, so we will gradually be building up an infrastructure of how to deal with the changing of the sun.

Noclevername
2012-May-27, 12:26 AM
The fusion candle idea was a fun idea for a story, but has anyone actually run the numbers? Is it even physically plausible, given the amount of energy available in hydrogen and the mass of the planets to be moved? Anyway, if you have controlled fusion on that scale that can fuse simple hydrogen (protium, not deuterium), and if you can move that much mass (planets!) around, starships would be pretty easy.
The ships are not the problem; it's the logistics of moving an entire planetary population that would be staggering. You'll notice I used the word simpler, not efficient-- energy efficiency isn't much of a concern if you have a gas giant's mass to play with. And there are other potential means of moving planets, given the timescale involved.


You could even have just one worldship, with a trivial mass compared to a planet, and carrying along frozen hydrogen balls for fuel. Something with the mass of a good sized asteroid could have a population of billions and given the timescales discussed here, it doesn't have to move very fast. So what if it takes 50,000 years to reach another star? (bold mine)

Now that's something I'd really like to see the numbers run on.

Another thought-- if you think it's really plausible to build a 50,000 year worldship, who needs another star system? Just move out into the Oort cloud and farm comets.

mutleyeng
2012-May-27, 01:37 AM
Another thought-- if you think it's really plausible to build a 50,000 year worldship, who needs another star system? Just move out into the Oort cloud and farm comets.

It seems to me this notion that we will all travel to other stars is a very 21st century perspective.
Once we have another few hundred thousand years worth of aquired knowledge of the universe, i struggle to see there being the eagerness to explore that we currently have, at least not in person.
It reminds me a bit of carl sagans "Contact". When you are an ancient and wise civilisation, the motivators will be very different than we have today.
I see them staying put too.
I also think that is one of the better explanations for the Fermi paradox, short of there not being anyone else out there.

eburacum45
2012-May-27, 06:20 AM
One scheme I've devised to exploit white dwarfs is the white dwarf ringworld concept. When a white dwarf cools to Sun-like temperatures, it has a habitable zone only about a million km out. That's a bit close for a planet, but a ringworld that big would give many thousands of times the habitable area of the Earth.

One problem with this is that such a ringworld would fly apart - no physical material is strong enough to make a ring orbiting fast enough to give one gee of centrifugal acceleration on the inside surface. There are two ways to get round that-

1/ you could make a very low-gravity habitat, preferably with a transparent roof to stop the weakly held atmosphere from flying away. This wouldn't be a very Earth-like environment, but I'm pretty sure it would be fun to live there, weighing almost nothing and flying like a bird amongst huge trees.

2/ you could make a double ring, with the inner ring rotating fast enough to create 1 gee of outward acceleration, and a second, more massive outer ring rotating much more slowly or not at all- this ring will be attracted by the white dwarf's gravity, and push inwards against the inner ring to counterbalance that ring's outward push. Float the inner ring on magnetic bearings (like an orbital ring (http://en.wikipedia.org/wiki/Orbital_ring)) and you have a vast habitable surface with standard Earth-like gravity.

One advantage of a ringworld is that you decide how big to make it; the white dwarf will slowly cool, so the ring will need to be made smaller over time. This will mean the soil layer gets gradually thicker, assuming the total remains constant.

To be honest, I don't think such things will be built, at least not very often - by the time a civilisation gets to the point where it can inhabit a white dwarf, it would probably be entirely electronic, or otherwise free of biological constraints. But you never know...

eburacum45
2012-May-27, 06:31 AM
Note that from the surface of such a ringworld the white dwarf would look the same size as our Sun does in the skies of Earth; as the dwarf cools, it goes from fantastically hot to Sun-like to cool red to black, but it is surprisingly temperate for billions of years.

Van Rijn
2012-May-27, 06:41 AM
My problem with a ring in that context is that it is extremely mass inefficient, and it forces everyone to have essentially the same living conditions. Small habitats would be much easier to build, and far more flexible. They can even be attached to a common structure (a very early idea I had was something like the Starlost Ark (http://www.snowcrest.net/fox/props/STARLOST.jpg), but with rotating O'Neill like habitats in place of the domes).

Van Rijn
2012-May-27, 07:28 AM
The ships are not the problem; it's the logistics of moving an entire planetary population that would be staggering. You'll notice I used the word simpler, not efficient


I doubt implementation would be simpler.



Now that's something I'd really like to see the numbers run on.


The KalpanaOne:

http://www.nss.org/settlement/space/2007KalpanaOne.pdf

is a space habitat concept that would take about seven million tons for a population of 3000, and assume a 10 billion population. I'll throw in a factor of 10 increase for attachment frame for the habitats and other materials. I get:

10,000,000,000/3000*10 = 33,333,333 times the mass of the Kalpuna One.

33,333,333*7,000,000 = 2.33e14 tons mass required

Psyche (just picking it from a list of large asteroids) is about 2.5e16 tons, so around a hundred times as much mass.


Another thought-- if you think it's really plausible to build a 50,000 year worldship, who needs another star system? Just move out into the Oort cloud and farm comets.

That's a possibility. The main reason for going to another star is the concentration of mass and energy, but there isn't any particular reason why they have to stay at another star. One strategy might be to migrate out of the galaxy, depending on what happens when Andromeda gets close. Perhaps they would star hop their way out.

eburacum45
2012-May-27, 02:26 PM
My problem with a ring in that context is that it is extremely mass inefficient, and it forces everyone to have essentially the same living conditions. Small habitats would be much easier to build, and far more flexible. They can even be attached to a common structure (a very early idea I had was something like the Starlost Ark (http://www.snowcrest.net/fox/props/STARLOST.jpg), but with rotating O'Neill like habitats in place of the domes).

That's a good idea. You could even connect the cylinders into a ring, to make a rungworld;
http://www.orionsarm.com/im_store/rungworld.jpg

caveman1917
2012-May-27, 02:48 PM
That's a good idea. You could even connect the cylinders into a ring, to make a rungworld;
http://www.orionsarm.com/im_store/rungworld.jpg

Why would you want to connect them to a common structure?

They'll be so close, and with such low surface gravity, that simple shuttle travel between them won't take much energy. And a common structure would be a huge engineering challenge compared to individual station keeping. Not to say that it will remove the flexibility and some of the redundancy inherent in having a swarm of individual cylinders.

Paul Wally
2012-May-27, 03:31 PM
If the human race survives that far into the future, we will have created technology that we can't begin to fathom in today's age. What would a person who lived just 1000 years ago think if he saw the world today? Now add an additional 1,000,000,000 years onto that.

I would also expect the human race to have colonized new worlds. Our population right now is 6.8 billion right now. I'd think the total population of our ancestors would be well into the quadrillions by that point. We would likely have colonized many new worlds, and since each world would basically be an island, each inhabited world would likely evolve into it's own unique species of human.

If we don't colonize new worlds, I see no way we survive that far into the future. The world has a limited amount of resources, and we use exponentially more resources as time progresses. If we can't figure out a way to get off of this planet, we will be doomed at some point.

I would expect technologies that seem absurd by today's standards. And if we have colonized new worlds, we will have an enormous population spanning several star systems. With such an enormous amount of resources, I could foresee civilizations using some sort of technology to collect matter in the galaxy and actually create their own custom made solar systems. Civilizations could create a sun like star, place a large brown dwarf out in the outer regions of the system and place a dyson sphere around the brown dwarf to collect energy while the populations live on custom made planets in the habitable zone around the star.

This sounds absurd, but if we survive for another billion years, technology that we can't even comprehend will be millions of years out of date!

Yes, a billion years is a very long time. I don't even think we're looking at an emergency evacuation scenario here, but more like gradual migration over geological timescales. So by the time the sun actual starts going red giant there may not even be any descendents of present-day humans on Earth. It's possible that the descendent's of dolphins, chimps or any other species could evolve into an intelligent civilization on Earth by that time. Another interesting question is: Could lizards, crocs and tortoises evolve to become dinosaurs perhaps due to climate change.

Also if plate tectonics continue the surface of the Earth will look different with perhaps different oceans and continents and most of the ancient human cities may be eroded, submersed in the ocean or covered by alluvial deposits. Perhaps the descendents of humans coming from other star systems will discover the Earth and archaeologists may discover that the legend of a certain planet called "Earth", birthplace of the humanoid civilizations, is true.

eburacum45
2012-May-27, 04:52 PM
Why would you want to connect them to a common structure?


Connecting long cylinders into a common structure prevents tumbling. This was one of the reasons Gerard O'Neill's Island Three cylinders were arranged in pairs; the two cylinders together can use the linkage to adjust the attitude of both cylinders so that the mirrors always face the Sun.
http://imageshack.us/f/227/oneillcolonyov9zb.jpg/

Short, fat cylinders and toruses (tori?) are more stable and won't tumble noticably, but longer cylinders are likely to start rotating end-over-end unless you compensate for this tendency somehow.

Githyanki
2012-May-27, 05:11 PM
I think this is a moot question as our descendants will figure out how to make the Sun go "Super-Nova", 13,769 years from now. That's 13,520 years after the all life on Earth was destroyed by the "Gray-Death".

caveman1917
2012-May-27, 07:27 PM
Connecting long cylinders into a common structure prevents tumbling. This was one of the reasons Gerard O'Neill's Island Three cylinders were arranged in pairs; the two cylinders together can use the linkage to adjust the attitude of both cylinders so that the mirrors always face the Sun.
http://imageshack.us/f/227/oneillcolonyov9zb.jpg/

Short, fat cylinders and toruses (tori?) are more stable and won't tumble noticably, but longer cylinders are likely to start rotating end-over-end unless you compensate for this tendency somehow.

A swarm of habitats like Island Three was what i had in mind, but i see that i said individual cylinders rather than individual habitats.
In any case, i don't see the benefits in linking them together in a huge ring. Rather the opposite.

eburacum45
2012-May-27, 09:31 PM
The main advantage would be easy communications between the cylinders: passenger, information, energy and matter transfer would be easier to achieve between linked habitats. However if a mass of linked habitats occupies too small a space, it will tend to self-gravitate and collapse like a cloud of dust.

A slowly rotating ring of linked habitats can remain expanded, even if it has a very large total mass.
http://www.bautforum.com/attachment.php?attachmentid=11922&d=1222462436

caveman1917
2012-May-27, 10:27 PM
The main advantage would be easy communications between the cylinders: passenger, information, energy and matter transfer would be easier to achieve between linked habitats.

Can't you just use the cylinders' rotation to fling and capture objects (shuttles, cargo modules) between eachother? Assuming by your picture about 600 habitats orbiting at a radius of 100000 km that puts an average distance of about 1000 km between them. Using island three designs (outer ring radius 8 km and rotation 40/h) would make the speed of such an object about 300 km/h, making the trip about 3 hours. This doesn't require engines on the shuttles, except for perhaps some emergency thrusters to make slight course corrections.

eburacum45
2012-May-28, 06:07 AM
Sure; it is perfectly possible to build a swarm of habitats with no physical connections, each habitat being serlf-contained and self-sufficient (so far as that is possible at all). You could put a vast swarm of unlinked habitats around a white dwarf and support a very large population for a very long time. Arrange them in a torus like this
http://www.orionsarm.com/im_store/JenkinsDysonSwarm.jpg
and they'll orbit without intersecting each other for the forseeable future, with very little station-keeping.

-----------
Another advantage to inhabiting a white dwarf system (apart from the very long temperate period) is that there is likely to be a lot of carbon in the system, to uses as a building material. A dying star in its final stages burns helium into carbon and oxygen; both very useful habitat-building materials. Most of this will be ejected from the system, but some will be captured by objects orbiting the star at a respectful distance and could be harvested in order to manufacture living room. Perhaps you could even dig it out of the star somehow, but with a surface gravity of around 100,000 gees this might be problematic...

caveman1917
2012-May-28, 01:04 PM
Arrange them in a torus

That configuration would make it a bit more difficult to use the "fling and capture" trick to exchange passengers and cargo between them.