What cosmological event could snuff out the sun without destroying Earth?

[CCWilson]

I'm considering writing a story in which we Earthlings have a few years to prepare for a cosmological catastrophe in which our planet will lose its energy source and be adrift in space. This would mean the end of life on Earth - but not right away. We could insulate giant underground chambers and tap existing energy sources in order to perpetuate human life for a number of generations into the future. Fun and complications would ensue.

So my first problem is figuring out how to create such a disaster in a believable way. I assume that long before our sun dies, it would go through a contraction phase to become a red dwarf or something and fry us for dinner. Do we believe that some stars of the size of the sun are capable of simply becoming dimmer and finally winking out? Didn't think so.

How about a scenario in which we become aware of an approaching mass - a planet-sized rock or black hole or something that we knew would hit our solar system and might somehow knock the Earth into a more distant orbit so that we would no longer receive enough sunshine to sustain life?

I'd appreciate any suggestions from you brainiacs.

 

[mfb]

- another star, crossing the inner solar system. Its gravity could modify the orbits significantly, or even catapult some planets into the interstellar region. It is possible to predict the motion of all nearby stars at least for (at least) the next hundred thousand years, giving a large time to prepare.
- a black hole, crossing the inner solar system. Similar to above, maybe harder to see in advance.
- a direct collision of a black hole and the sun. Similar to above, but I would expect that the sun will not survive this. Might have some bad side-effects.
- sufficiently advanced technology, earth-based or alien (moving the Earth is way easier than messing around with sun)
- in several billion years, sun will become a red giant, burning everything on the surface and probably swallow earth. If not, the sun gets smaller again, reducing its luminosity. If some life somehow survived this, it will face an eternity of (nearly) darkness.

As you can see, the sun is quite robust. Just one option I found (the direct collision with another object of stellar mass) really modifies the sun in a significant way before it dies.

 

[mathman]

The end of life for the sun has it becoming a red giant, which might swallow up the earth. To avoid this you need to have the Earth leave the solar system ahead of time (how?).

 

[DrStupid]

How about a scenario in which we become aware of an approaching mass - a planet-sized rock or black hole or something that we knew would hit our solar system and might somehow knock the Earth into a more distant orbit so that we would no longer receive enough sunshine to sustain life?

An object with the mass of the sun could kick us out of the system:

http://tinyurl.com/9e2c6v7

Stop simulation to see the parameters. Than fix the sun and start simulation.

 

[CCWilson]

Thanks for your replies. A star couldn't sneak up on us, so that's out for the purposes of the story. So a black hole might be the best candidate, unless an object larger than Jupiter - perhaps a planet from another star system - is possible.

DocStupid, that's a great simulation. Out of curiosity, how did you come to construct it originally? I assume that a black hole the mass of the sun could do what your generic object does in the simulation and sling Earth out into space, as long as it didn't contact us directly.

In the story, scientists would need to become aware of the approaching black hole or whatever several years in advance, so that they would have time to construct a permanent underground city. Since I don't believe that there are any objects that we know about between our solar system and the nearest star, I don't see how the gravitational effects of an approaching black hole would become obvious to us.

One possibility is that a massive black hole is captured in orbit around the sun, so that scientists would become aware of it from its effects on the outer planets, and as the orbit of the black hole slowly spirals inward, scientists would be able to calculate its future effects on the Earth. Perhaps it would be in a big elliptical orbit and we would know at some point it would be destined to cause a slingshot effect as in DrStupid's simulation.

 

[onomatomanic]

You probably already considered and discarded this, but darkening Earth's sky is a lot easier to accomplish than switching off the Sun, and has similar effects.

In the usual scenarios (nuclear winter, volcanic winter, impact winter), the darkening occurs in the wake of some primary global catastrophe, but it shouldn't be too hard to come up with a scenario that gives you the one without the other, if that's important. For example, there were serious concerns that something rather less dramatic like a sufficiently large number of burning oil wells could have a similar effect (cf wikipedia section on "Kuwait wells in the first Gulf War"). So, make a really big fire somewhere, and it gets really cold everywhere else. And stays that way for as long as the fire burns, and then some.

Of course, the psychological factors are nevertheless quite different in the two situations. Switch off the Sun, and that's it for Earth, all that's left is holding out for as long as possible. Darken the sky, and you know it's going to get better eventually, even though you may not live to see it.

 

[mfb]

Hmm... objects with a mass comparable to Jupiter might work, too. They have to come very close to Earth (which gives a lot of side-effects like extreme tides), but they are hard to detect.

Black holes could be detected by their gravitational influence, as they would move the apparent position of stars. Gaia should be able to measure the position of many stars with a precision of ~100µas. For a black hole (BH) of 1 solar mass, this corresponds to light passing the BH with a distance of ~2.5*10^10km = 150 AU. Within a year, Gaia will perform several measurements of ~1 billion stars in the full solid angle. Those stars are not distributed evenly in the sky, but I will use this assumption here. Therefore, Gaia can observe a BH if a disk with 150 AU diameter occupies 1/billion of the sky. This gives a radius of ~40 light years. With 100km/s, this corresponds to 120,000 years. Hmm...
Of course, the assumption of a uniform distribution is wrong. Most stars are within the galactic disk, and not close to the sun. But so are most black holes...

Jupiter is lighter by 3 orders of magnitude, reducing all numbers by 3 orders of magnitude. With the same method, we could detect it in a distance of ~2500 AU, giving about 100 years time to prepare. That looks good.

Earth needs a kick of ~20km/s to escape. Using a=GM/r^2, delta_v=a*delta_t, delta_t ~= r/v, v=50km/s, this corresponds to a distance of closest approach of the order of 100,000km - about twice the radius of Jupiter, and comparable to the Roche limit, meaning that Earth would probably break into pieces if the object gets so close. I ignored prefactors here, the distance might be larger by a factor of ~2-3, but tidal forces would be extreme and significantly change the shape of Earth - not a good place to build bunkers.

One possibility is that a massive black hole is captured in orbit around the sun

Not without technology. There are no objects of sufficient mass to capture the black hole.

and as the orbit of the black hole slowly spirals inward

There is no reason why it should do this.

 

[CCWilson]

Thanks, mfb.

There are no objects of sufficient mass to capture the black hole.

Let's say that a black hole with the mass of the sun is approaching our solar system. First of all, how likely is it that there are black holes traveling through space after having been expelled from another star system? If such existed, can we assume anything about its velocity? Is it possible that it would be traveling slowly enough that the gravitational attraction between it and the sun would allow the two to orbit around each other (much like binary stars do)? And if that happened, what would be the effect on Earth even before the proposed slingshot effect?

 

[CCWilson]

Black holes could be detected by their gravitational influence, as they would move the apparent position of stars.

I had wondered about that possibility. Any idea how accurate scientists could be about the speed and pathway of a sun-sized black hole that approached our solar system? In other words, would they be able to predict not just that it would pass through our solar system, and when, but that it would pass by the Earth in such way as to slingshot it out into space?

 

[DrStupid]

Hmm... objects with a mass comparable to Jupiter might work, too.

I'm not sure about it. This looks like as if it works:

http://tinyurl.com/c9ezmrb

But it is more a collision than a swing by. Earth would be heavily damaged or even destroyed.

In this case the object has ten times the mass of Jupiter:

http://tinyurl.com/corrbmm

As the minimum distance exceeds the Roche limit Earth would at least survive the event.

 

[Chronos]

A solar mass black hole would be unusually small. We have not detected any to date that are much less than about 5 solar masses [an interesting question unto itself]. A brown dwarf, on the other hand, would be much more probable given they are believed to be one of the most common type of star in the galaxy. They are extremely faint, but, typically in the range of 13 to 80 times the mass of jupiter. A body this size would wreak considerable havoc on planetary orbits were it to pass through the inner solar system. Chances are good they would be less than 50 years away, and quite possibly much closer, before detected. Our first clue could well be a sudden increase in the number of comets passing through the inner solar system. It is entirely possible such an event has already occurred in the history of our solar system.

 

[mjacobsca]

Scientists would know pretty early that a black hole were approaching. As suggested earlier, gravitational lensing would be significant from a measurement standpoint. I believe numerous pulsars are currently used for looking for gravitational waves (search for pulsar timing array). Space telescopes like Kepler rely on precise measurements as well. Both projects would know almost instantaneously that something was wrong, long before we could see what was approaching. *Most experts on those teams would realize fairly quickly that the stars had "moved", and there are very few beneficial reasons for such an event. A black hole would be among the first things considered.

Another effect of an approaching black hole would be a disturbance in the Oort Cloud, the vast region of space beyond Pluto, and extending as much as 3 light years from the Sun, and consisting of trillions of asteroids, comets, and dwarf planet-sized objects like Pluto. The Sun has very little gravitational influence on these objects. They are very loosely bound to the Sun, and any large passing object will throw them off their orbits, either into the solar system or out. A few cosmic impacts with outer planets would be quite interesting from a sci-fi perspective. Of course, a minor impact on Earth or a big one on moon would be fun, too.*

Tidal forces would affect oceans once the black hole start exerting influence on the earth. This could happen 20 years before it got here, allowing for other interesting events.*

A black hole would be almost impossible to capture by our Sun. It would have to be going slow enough already, which is improbable. A close approach and slingshot is more likely. * Also, it would be very hard to fling the Sun out from the solar system without the earth. It would be much more likely for a close call with the Earth flinging the Earth out of orbit instead. Maybe Mars can go with us for *fun. :) Or perhaps the black hole could get so close to the Sun that it sucks away part of the Sun's outer layers? I don't know what effect that would have.*

Perhaps an interesting plot could be that the black hole will miss us, and everything will survive, and everyone rejoices. The black hole missed the keyhole region that it needed to hit. *But then a second black hole is discovered; a binary partner trailing a light year behind. This one will hit the keyhole precisely, and hopes are dashed.*

I look forward to reading this story!

 

[mfb]

First of all, how likely is it that there are black holes traveling through space after having been expelled from another star system?

They don't have to be expelled anywhere, all stars have a motion relative to other stars on their own.

If such existed, can we assume anything about its velocity?

A typical velocity is ~20km/s (while some have 200km/s+), gravity would increase this to ~50km/s close to the orbit of earth. As pessimistic values, I used ~100km/s for the approach (very high -> short warning time) and ~50km/s for the close approach (low -> large gravitational influence).

Is it possible that it would be traveling slowly enough that the gravitational attraction between it and the sun would allow the two to orbit around each other (much like binary stars do)?

No. In a two-body system, a capture process is impossible. The object cannot be bound gravitationally, otherwise it would have been close to the sun forever.

Any idea how accurate scientists could be about the speed and pathway of a sun-sized black hole that approached our solar system?

I am quite sure that the discovery of such a BH will lead to some new telescopes to track it, and telescopes improved so much in the last decades - impossible to tell how good the estimates are in 100 years, yet in 100,000.@Chronos: See my estimate for the gravitational bending of light for black holes, it can be scaled to objects of any mass. Current technology (Gaia, to launch in 2013) can give a warning time of the order of 100years*objectmass/(jupitermass).

 

[CCWilson]

In playing with DrStupid's excellent simulation, it's obvious that the pathway through the solar system isn't all that critical in terms of whether it gives Earth a new orbit or an escape velocity. Many combinations will do that. It IS critical as to whether our planet is destroyed or not, which is important, I guess. I did see that the mass of the black hole needs to be close to that of the sun in order to have the desired effect - much smaller and unless it got lucky it wouldn't do a lot, much bigger and we'd soon be within its event horizon.

Chronos, a brown dwarf is an interesting possibility, but would have to hit just right to disturb Earth's orbit, according to the simulation.

If a sun-sized black hole were heading right in our direction, would that make it easier to detect it, or harder?

 

[CCWilson]

Another effect of an approaching black hole would be a disturbance in the Oort Cloud, the vast region of space beyond Pluto, and extending as much as 3 light years from the Sun, and consisting of trillions of asteroids, comets, and dwarf planet-sized objects like Pluto. The Sun has very little gravitational influence on these objects. They are very loosely bound to the Sun, and any large passing object will throw them off their orbits, either into the solar system or out. A few cosmic impacts with outer planets would be quite interesting from a sci-fi perspective. Of course, a minor impact on Earth or a big one on moon would be fun, too.*

Thanks, mjacobsca. The Oort cloud sounds like my best shot at detecting the black hole at approximately the right time frame, if I'm to be cosmologically accurate, which I want to be.

 

[Chronos]

Lorenzo Iorio published a paper on this scenario a couple years ago - Is it plausible to expect a close encounter of the Earth with a yet undiscovered astronomical object in the next few years? http://arxiv.org/abs/1009.1374 where he concluded such an event was highly improbable. Obviously, extrapolating this analysis out to 50-100 years significantly increase the probability. Were it traveling at about the same velocity as the sun around the galaxy [~220 km/s], but, in the opposite direction, it would travel about 0.25 AU per day. Assuming its arrival in 50 years, it would currently be around 4500 AU from earth. As a basis for comparison, the aphelion of Haleys comet is about 35 AU.

 

[H2Bro]

I am surprised that no one has mentioned hypervelocity stars, which are stars / stellar masses that can have velocities three times that of our Sun's around the galaxy. Here's yet-another awe-inspiring Hubble feat (http://www.popsci.com/technology/ar...mage-speeding-star-expelled-center-our-galaxy), actually detecting one such star which had been part of a trinary orbit until one member was absorbed by the SMBH at the center of our galaxy, transferring the momentum to the other two.

So, one might consider a binary orbit where one member goes supernova and the other gets hurled off on a tangent (as this event could happen far from the center of the galaxy). Still it would take very long for this star to approach the Earth...

Isaac Asimov has a book detailing various ways the Earth might end due to cosmological occurrences. It is highly entertaining to read as it is, and could spark your imagination if not provide an outright answer. https://www.amazon.com/dp/0449900487/?tag=pfamazon01-20

 

[CCWilson]

Thanks, H2Bro. I've just placed my order for Asimov's book through Amazon. I think the timing for a star, hypervelocity or otherwise, wouldn't work for my story, though.

 

[twofish-quant]

If you want to get speculative, let's suppose in 2300 some even genius creates at field that changes the fine structure constant by affecting the Higgs field. He holds the world for ransom, turns off the core of the sun, and then he gets paid, turns off the field and the sun still stays off.

Ooopppsssss...

If the nuclear core of the sun goes off then the sun will still shine for several thousand years.

 

[CCWilson]

All right. At this point we have Earth leaving the solar system and underground cities keeping our species alive. What happens to our planet's atmosphere? Do we lose some of it as the black hole passes nearby? Once we are no longer being warmed by the Sun, with all plant and animal life above ground exterminated, do we maintain our atmosphere, or is it slowly lost into space? Could someone in an insulated space suit walk around and get his oxygen, warmed before breathing it, from the air? How chilly would it be?

Incidentally, I'm sure it depends on how close the black hole passes Earth, but should we expect earthquakes and tidal waves before we are slung away from mother Sun?

 

[DrStupid]

What happens to our planet's atmosphere?

Very far away from the Sun it will condense. There is a good description in "A Deepness in the Sky" from Vernor Vinge.

 

[twofish-quant]

Could someone in an insulated space suit walk around and get his oxygen, warmed before breathing it, from the air?

Free oxygen is extremely reactive and unless you have something that is generating it (i.e. plants) pretty soon it's going to disappear from atmosphere.

 

[H2Bro]

If the nuclear core of the sun goes off then the sun will still shine for several thousand years.

I've read its more like a million years for photons to finish their random walk through the photosphere and exit the sun.

How's this for far-fetched...

Astronomers observe a red giant being stripped of matter by a binary black hole companion. They predict within 10 years the red giant will completely break apart and fall into the black hole. Coincidentally, the axis of rotation of the black hole is somehow determined to be precisely aligned with our Sun. As a result, when the star falls in the black hole will release a colossal gamma ray burst (GRB)

What does the GRB do to the Sun? anyone's guess. maybe it blasts off the corona and several neptune-equivalent masses of plasma are thrown off into space. I'm sure this is an event you could run with in terms of outcomes, and not too many people would say "thats not what would happen" (except on this forum, hehe).

Oxygen would freeze out of the atmosphere into snow and over time bind itself to iron in the soil. You might be left with a snowy covering of CO2 and Nitrogen, however.

EDIT: not actually 'snow', but a crystallized solid form of oxygen.

 

[mfb]

A GRB which can harm the sun would probably blast away the upper parts of earth, too. This is not limited to the atmosphere.@CCWilson: A black hole can kick Earth away without significant tidal effects.
In liquid form, our atmosphere would be a layer of ~10-15m height, distributed over the oceans.

 

[Ryan_m_b]

Interesting idea for a story. Something you're going to want to think about is the settlements themselves. We have no idea at this time how to make closed ecological systems, this is going to be a must if anyone is going to survive underground once the Earth's biosphere has failed. Consequently a long time to prepare (50-100+ years) might be needed for the R&D. Also you might want to give some thought as to the societal factors both physical and social e.g.

- What economic systems will be in place? Current models rely on growth but in such an underground vault set up steady-state systems with an emphasise on recycling may be better. Also how much private vs public ownership will be in place? It's all very well being free market until a monopoly on oxygen recycling forms.
- How good is the political set up? In the long run bad political systems tend to result in emigration and/or revolution. In a closed ecosystem the first is impractical and the latter catastrophic.
- How many people? It only takes a few thousand for sufficient genetic diversity but millions to adequately fulfil the specialist labour requirements of a technological civilisation.
- What nationalities/cultures and how will they clash? If the R&D and construction of these vaults is by economically developed countries how will less economically developed countries react? What will the social implications be for a minority group who are the few remaining survivors of an ethnicity/nationality/religion etc? What are the implications of a sudden, confined mixture of cultures (possibly violently incompatible)?

Hope this helps!

 

[H2Bro]

I've always found the social, economic, and political tensions/repurcussions of drastic shifts in technology to be the joi d'vivre of reading science fiction.

Kim Stanley Robinson has a great Mars series, (Red Mars, Green Mars, Blue Mars). As I recall there was some fairly good insight into closed-loop ecosystems and habitation, which they set up in the first novel (red mars).

One thought I have is that in such a scenario, it would be quite easy to justify imposing a totalitarian regime. First off, its a basic survival competition, everything is scarce, so the argument that there's no room to indulge personal fantasies or dreams, or that everyone needs to suffer hardship for the greater good, are hard to defeat. Second, the very nature of the infrastructurally-dependent society lends itself to totalizing power structures, e.g. the Recycling engineers guild, or whoever captures the power generators. Also, in a society that survives by adapting to scarcity, a natural ethic or ideology of minimizing consumption would emerge. Today we might evaluate a persons success by their nice home, or new car, etc. In that world, it might be more on how efficient you are in water usage, or calorie metabolization, or thrify in re-purposing broken tools, machines, etc.

For that, you might find literature on life in the Eastern bloc most informative. They necessarily adapted to living in a totalizing society that controlled all major industries, and quite often prided themselves on their thriftiness in getting on without consumer goods, or re-using re-building old discarded machines.

 

[CCWilson]

Ryan, I have been thinking along some of those lines. I believe that multiple underground cities would be built, each served by a nearby power plant, one or several by every nation or group of nations with the economic wherewithal. And the psychology of being on an eventually doomed planet, the physical, political, economic, and cultural adjustments to life in a bunker, the process of selecting who's to populate those cities - there's a lot of potential there. At some point I'll need to get together with people who will help keep the story on the straight and narrow with respect to scientific and technological plausibility.

 

[Ryan_m_b]

I've always found the social, economic, and political tensions/repurcussions of drastic shifts in technology to be the joi d'vivre of reading science fiction.

Agreed!

Kim Stanley Robinson has a great Mars series, (Red Mars, Green Mars, Blue Mars). As I recall there was some fairly good insight into closed-loop ecosystems and habitation, which they set up in the first novel (red mars).

The Mars Triology was quite good for that, it stands out for me as one of the few real explorers of new economic models.

One thought I have is that in such a scenario, it would be quite easy to justify imposing a totalitarian regime.

It would also be physically easy to implement. Keeping a closed ecosystem going would require ubiquitous surveillance (tracking animal/plant/fungi/microorganism population numbers, interactions and diversity, monitoring the status of critical machinary, surrounding rock etc). Not only that but the ability to finely control the environment to alter any of these parameters. In such a system dissent could be easily detected and dealt with, there's no real way to form a resistance and a violent revolution in a confined closed system could be catastrophic.

However it's not the only way things may go and given the possibility (however slim) of violent revolution it might not go that way. A better system could be one of widespread consumer co-operative enterprises or direct public ownership.

Ryan, I have been thinking along some of those lines. I believe that multiple underground cities would be built, each served by a nearby power plant, one or several by every nation or group of nations with the economic wherewithal. And the psychology of being on an eventually doomed planet, the physical, political, economic, and cultural adjustments to life in a bunker, the process of selecting who's to populate those cities - there's a lot of potential there. At some point I'll need to get together with people who will help keep the story on the straight and narrow with respect to scientific and technological plausibility.

Indeed there's lots of interesting scope for story. Just thinking about what the culture and psychology (not to mention technology) of the people entering the cities would be after generations of effort to build these things because the end of the world is comming (and only a few will survive) is an effort!

 

[twofish-quant]

- How good is the political set up? In the long run bad political systems tend to result in emigration and/or revolution. In a closed ecosystem the first is impractical and the latter catastrophic.

I'd imagine that a millennialist religious theocracy would work well in this situation. The end of the Sun is a sign from God. The other thing is that if it's obvious that everyone is going to die in the end, I think "rational" people would likely give up. It's the people that think that God will perform a miracle if we are all good, that are likely to keep going forward.

As far as the social setup, I think something military would work. Militaries deal with small closed social systems, and the number of people is small enough so that any sort of dissent would be quickly wiped out.

- How many people? It only takes a few thousand for sufficient genetic diversity but millions to adequately fulfil the specialist labour requirements of a technological civilisation.

But we are in survival mode. One thing about a sudden population crash is that the economy is likely to be based on scavanging. One thing about a "cold earth" is that it's likely to leave a lot of technology in good shape. If you have a car that leave it out in normal temperatures, it will disintegrate in about a century. If you have a car and freeze it in liquid nitrogen temperatures for a thousand years, I'd imagine that it would be *possible* to have it working.

So I can imagine that "technology" would consist of being able to mining old machines and make them work, and I can imagine a religion growing up around this. You have "wizards" that know the secret methods of getting an engine from the surface and have it work rather than explode.

 

[Ryan_m_b]

I'd imagine that a millennialist religious theocracy would work well in this situation. The end of the Sun is a sign from God. The other thing is that if it's obvious that everyone is going to die in the end, I think "rational" people would likely give up. It's the people that think that God will perform a miracle if we are all good, that are likely to keep going forward.

I'm not so convinced, I think the majority of people whether they are religious or not would want the human race to survive. I don't see why it would be rational to give up that sounds like one of those weird criticisms of atheists that they must have no hope without god.

As far as the social setup, I think something military would work. Militaries deal with small closed social systems, and the number of people is small enough so that any sort of dissent would be quickly wiped out.

Hmmm, the problem IMO with a military set up is that whilst it is good for undemocratic organisations that people voluntarily (or temporarily) join I think it's a bad way to run a society at large. Militarism generates a large amount of social tension and this would go further, almost Khakistocracy! It seems that the social set up has to be rigid enough to act quickly and decisively but flexible enough to adapt and satisfy the social need for freedom.

But we are in survival mode. One thing about a sudden population crash is that the economy is likely to be based on scavanging. One thing about a "cold earth" is that it's likely to leave a lot of technology in good shape. If you have a car that leave it out in normal temperatures, it will disintegrate in about a century. If you have a car and freeze it in liquid nitrogen temperatures for a thousand years, I'd imagine that it would be *possible* to have it working.

So I can imagine that "technology" would consist of being able to mining old machines and make them work, and I can imagine a religion growing up around this. You have "wizards" that know the secret methods of getting an engine from the surface and have it work rather than explode.

I don't really see that as working very well at all. I doubt the majority of modern equipment would survive in such conditions and if you don't have the expertise to fix and maintain them you're in trouble. Not only that but the knowledge to use them would have to be kept known by someone, you can't just rely on having it written down and try to get people to self-learn when you need it. I could go on but others have put it better.

 

[CCWilson]

I suspect that such an event would shatter the religious beliefs of a lot of people. This kind of catastrophe would be so unlike what most believers thought God had in mind for us, so different from what their holy books predicted, so unimaginable as the act of a loving God, that there might well be a turning away from religion. Still, there's no limit to our capacity for self-delusion, so maybe not.

I also think that the survival of our species and of life in general would be embraced as a personal responsibility by most of those selected to populate the underground cities and even by many who didn't make the cut and would be, therefore, doomed. We do have the capacity for altruism and self-sacrifice and a drive to do the right thing under some circumstances, after all, and what cause more compelling than the survival of humanity could there be? After the first generation, though, selfishness would make a comeback, idealism would decline, and the course of life underground would be unpredictable.

 

[Sanescience]

If science jargon is not your forte, don't try to explain it. Just have the brightness of the Sun diminish for "no reason". If heat takes a million years to escape from the core, then the core quenched a million years ago and now we're seeing the effect.

In Stephen Baxter stories "Xeelee Sequence" all the stars of the universe are fading because of aliens called Photino Birds modifying the stars to suit their purposes. The books are pretty cool.

 

[twofish-quant]

Hmmm, the problem IMO with a military set up is that whilst it is good for undemocratic organisations that people voluntarily (or temporarily) join I think it's a bad way to run a society at large.

Sure, but we are talking about the sun going out.

One thing that will make it a lot easier for a military/theocratic dictatorship to function is that I think we are talking about small numbers of people. Instead of a total populations of billions, we are maybe talking about a 100,000 at most, and if you deviate slightly, that's an excuse to send you out the airlock...

One thing about this world is that I'm getting the feeling that aside from the sun going out, any society that survives is going to be rather unpleasant.

It seems that the social set up has to be rigid enough to act quickly and decisively but flexible enough to adapt and satisfy the social need for freedom.

I suspect that in this situation anyone that wants freedom is going to end up out the airlock.

I don't really see that as working very well at all. I doubt the majority of modern equipment would survive in such conditions and if you don't have the expertise to fix and maintain them you're in trouble.

But the knowledge to fix and maintain is much less than the knowledge needed to build something. I can make basic repairs to a car or a computer. I couldn't build one from scratch.

 

[Ryan_m_b]

Sure, but we are talking about the sun going out.

One thing that will make it a lot easier for a military/theocratic dictatorship to function is that I think we are talking about small numbers of people. Instead of a total populations of billions, we are maybe talking about a 100,000 at most, and if you deviate slightly, that's an excuse to send you out the airlock...

100,000 seems far to small to maintain a high tech society. Remember it can't be anything but a high tech society, more so than ours IRL because it has to be able to build and maintain closed ecosystems. The thing about high tech societies is that the labour force has to contain many skilled, specialised labourers. There might be some ways of cutting down and making systems more efficient but I can't see anything less than millions. Any modern device has a huge background of support industries to make, gone are the days when a few hundred craftsmen could knock up most of what society produced.

Given this, the need for genetic diversity and the strong culture of trying to ensure the human race survives I highly doubt execution would ever be put into effect. You don't spend generations trying to save a splinter of the species and then start killing people off without extremely good reason. More likely crimes or anything like that would be dealt with by some sort of compulsory labour.

But the knowledge to fix and maintain is much less than the knowledge needed to build something. I can make basic repairs to a car or a computer. I couldn't build one from scratch.

See above, the complexity of the modern technosphere (let alone one in a closed ecosystem for millions of people) is such that it takes a huge specialised and skilled labour force.

 

[twofish-quant]

100,000 seems far to small to maintain a high tech society. Remember it can't be anything but a high tech society, more so than ours IRL because it has to be able to build and maintain closed ecosystems.

1) It doesn't have to build them. Just maintain.

2) The other question is how closed does the ecosystem really have to be. For example, if you have a spaceship and you leak oxygen, then you are dead. Even with a dead Earth there are going to be supplies of oxygen lying around. It might be frozen oceans of oxygen. It could be ice that can be broken down by electrolysis.

3) Finally my gut feeling is that the small the number of people, the more easier it will be to maintain a closed ecosystem

You don't spend generations trying to save a splinter of the species and then start killing people off without extremely good reason. More likely crimes or anything like that would be dealt with by some sort of compulsory labour.

From a "mouths to feed" people are easy to replace. The reason I think that "life will be cheap" is that when resources are limited, one less person is one less user of oxygen.

 

[Ryan_m_b]

1) It doesn't have to build them. Just maintain.

Given the huge variety and complexity of equipment inherint in modern life this doesn't change much. Also part of maintenance will be replacing damaged parts that innevitable wear and tear will damage, these are going to have to be built.

I'm not just talking about the systems to maintain the ecosystem here, I'm talking about all the technology we need in everyday life and all the technological industry required to provide that from factory robotic arms to MRI machines.

2) The other question is how closed does the ecosystem really have to be. For example, if you have a spaceship and you leak oxygen, then you are dead. Even with a dead Earth there are going to be supplies of oxygen lying around. It might be frozen oceans of oxygen. It could be ice that can be broken down by electrolysis.

Sure there are advantages of being able to harvest from the world but you've still got to keep an ecosystem going. That's no mean feat juggling so many species interactions when failure will result not just in habitat destruction but possibly the end of the human race.

3) Finally my gut feeling is that the small the number of people, the more easier it will be to maintain a closed ecosystem

I'm sure there's an optimum number decided by the carrying capacity for the ecosystem and the labour force needed to maintain it but that's ignoring every other part of industry.

From a "mouths to feed" people are easy to replace. The reason I think that "life will be cheap" is that when resources are limited, one less person is one less user of oxygen.

There's a lot you're not taking into account. A skilled worker requires a significant investment, you can't just execute your uppity neurosurgeons and replace them in 9 months time. For a skilled worker you need at minimum one full time adult for 5-10 years to make sure it doesn't die from starvation, disease or accident. For support this requires the input of specialist products e.g. vaccines, nutritious food, developmental toys which all rely on other workers and industries for everything from child psychologists to chemical factories. Then you need 10-15 years of education to get them to graduate level (with all the associated industry and workers) which makes them entry level tea-making-person for a period of years until they have the relevant experience to be considered a fully fledged skilled worker in their field.

Bottom line a high tech civilisation has a wealth of hidden complexity (just look at your smartphone and try to think of how many industries and skilled workers have had a hand in it e.g. exotic material mining, software writers, transport logistics etc) filled by skilled labourers and both they and the infrastructure are huge investments in resources. You can't just stick anyone onto a training course and in a short amount of time get a skilled worker. It takes years and it takes a large education sector stocked with current skilled workers (in other words you need to keep a pool of every speciality perpetually to prevent the loss of noncodified and tacit knowledge).

 

[twofish-quant]

I'm not just talking about the systems to maintain the ecosystem here, I'm talking about all the technology we need in everyday life and all the technological industry required to provide that from factory robotic arms to MRI machines.

I think that if the sun goes out people won't be worried too much about factory robotic arms or MRI machines. Given the difficulties involved in merely surviving I don't think there would any energy to do any more than that.

Sure there are advantages of being able to harvest from the world but you've still got to keep an ecosystem going. That's no mean feat juggling so many species interactions when failure will result not just in habitat destruction but possibly the end of the human race.

I think people will give up on trying to maintain species diversity and just merely do what it takes to keep a small number of people (100,000 at most) alive. Probably closer to 3000.

There's a lot you're not taking into account. A skilled worker requires a significant investment, you can't just execute your uppity neurosurgeons and replace them in 9 months time.

Frankly, I don't think there would be much need for neurosurgeons. Anyone that needs neurosurgery would be assumed to be dead already.

For support this requires the input of specialist products e.g. vaccines, nutritious food, developmental toys which all rely on other workers and industries for everything from child psychologists to chemical factories.

I think that all of that would be gone. We'd end up with medieval conditions, with only the bare knowledge needed to maintain life support. Anything and anyone else will be expendable.

Bottom line a high tech civilisation has a wealth of hidden complexity (just look at your smartphone and try to think of how many industries and skilled workers have had a hand in it e.g. exotic material mining, software writers, transport logistics etc) filled by skilled labourers and both they and the infrastructure are huge investments in resources.

Sure. That's why I don't think that we will end up with a high tech civilization. What I envision is a small group of people underground near a geothermal energy source that provides heat. Once you have heat, you can generate enough electric power to electrolyze water so that you can replace oxygen losses. Now if you can replace oxygen, then food, water, and heat are things that don't require a huge amount of high technology to maintain.

Low tech with the KISS principle. Oxygen, water, food, heat, with simple robust technology. I think that anything that requires any sort of specialist technological expertise to fix is going to be non-functional in a year.

 

[twofish-quant]

Also, if we have 100 years to prepare, I think it would be a terrible idea to have one settlement. What you really want are thousands of settlements, so that any thing that destroys one settlement doesn't destroy everything. You probably want a settlement that takes a high tech strategy and one that takes a low tech one, so that someone will survive.

 

[Ryan_m_b]

I think you're right except for the fact that your entire idea of returning to a quasi-hunter-gatherer state fails in the face of the need for a closed ecosystem. It's nowhere near as simple as just having some heat and oxygen. Have you ever looked into how complex an ecosystem is? You've got to produce one able to healthily sustain a human population for a long time in a small area. That's going to require highly advanced technology to monitor and manipulate at the required level.

The smaller an ecosystem is the less stable it is going to be as there is greater chance for individual or small groups of species to become critical to the food web meaning that when something happens to lower their numbers it sends catastrophic shockwaves. The smaller and more isolated the ecosystem the more disasterous this will be for humans.

This is of course tapdancing past how ecosystems would be build in underground caverns capable of sustaining humans.

 

[twofish-quant]

I think you're right except for the fact that your entire idea of returning to a quasi-hunter-gatherer state fails in the face of the need for a closed ecosystem. It's nowhere near as simple as just having some heat and oxygen. Have you ever looked into how complex an ecosystem is?

Yes, but since we are creating an artificial one, it's probably best to use the KISS principle and create a minimal surviable system rather than even begin to try to replicate a complex ecosystem. The model I was using was that of a Mars colony or spacecraft to Mars. I can imagine how a spacecraft to Mars with say 50 people would work. I couldn't imagine the complexity of trying to create a spacecraft with a million people, so at least for one of the colonies, I'd suggest not even trying.

 

[Ryan_m_b]

Yes, but since we are creating an artificial one, it's probably best to use the KISS principle and create a minimal surviable system rather than even begin to try to replicate a complex ecosystem.

The minimum complexity for a redundant, sustainable ecosystem is likely to be huge. Even systems that seem simple have a wealth of hidden complexity; just think of crops and how they rely on soil fauna (all the thousands of species) or insect polinators and then how each of those species requires others etc etc. Mentioning that also makes me think of the human (and all animals for that matter) microbiome and how we'd have to somehow ensure the environment could provide this.

The best idea I can think of would be to investigate some of the most isolated ecosystems that can sustain humans and try to replicate them.

The model I was using was that of a Mars colony or spacecraft to Mars. I can imagine how a spacecraft to Mars with say 50 people would work. I couldn't imagine the complexity of trying to create a spacecraft with a million people, so at least for one of the colonies, I'd suggest not even trying.

I wasn't using a spacecraft model because they aren't sustainable. You may have some recycling and repair facilities but at the eventually they will run out of their stockpiled resources and die.

Considering the goal here is the continued survival of the species I don't think this action of delaying the innevitable would help.

 

[Maiklas]

I have a few ideas...

I like the idea of a steampunk sort of colony. Almost every mine in the world is going to be taken over by refugees. Deep down, the Earth is hot, of course, from its formation and radioactive decay, so refugees are going to look to live in the Goldilocks zone of temperatures, not too shallow or deep. They would drill deeper for hot water and steam to turn to power. With power comes light, which can produce plants, which can produce oxygen and food. Maybe it's all really hard to make this work, and tens of thousands of mining colonies would fail to survive. Still, some colonies could have found a way. I don't think it's so hard as some of the above posters say, as it need not be a truly closed system. They can dig to expand their underground world and resources. They might be able to wear arctic clothing and carry oxygen tanks to go topside for short expeditions. If I were writing the story, I'd alternate the narrative between two underground colonies: a nuclear-powered colony created by a superpower like America, and a steampunk colony founded by miners, like in an African diamond mine or California gold mine. It would be interesting to see the nuclear-powered colony having social problems and the steampunk colony having technical breakthroughs.

Idea #2 is that the underground colonies would have to defend themselves from those still surviving topside. You might get some inspiration from the mysterious Sea People, who invaded/migrated into many of the Mediterranean civilizations circa 1600 B.C. "Coincidentally," around that time there was a major volcanic eruption that probably blocked out the Sun.

Idea #3 is that aliens could be responsible for the calamity. Analogous to how we used gravitational slingshotting to get Voyager and other probes to the outer planets, the aliens could have set up a masterful "billiards shot", perturbing small objects in the Oort cloud that result in more and more powerful interactions that eventually result in the Earth being ejected from the Solar System. There has to be a reason they don't simply send a dinosaur-killer asteroid at Earth, so how about that they want to colonize and they are cold-loving aliens? Maybe cold-fusion based biology or some cold-based biology beyond our current understanding. Their cold-natured ways would explain why they are so darn patient with the decades or centuries that their "billiard shot" would need to play out - they live a very long time and move slowly. The Earthlings would not know about the aliens; it would be just one theory to explain the extraordinary bad luck of a shower of Oort cloud objects destabilizing the orbits of Mercury, Venus, and ultimately the Earth. You can wait to reveal the aliens in the second novel, when, a couple centuries later, colonizing aliens are surprised when Earthlings start popping out of the ground to interfere with their efforts. The aliens would be ill-prepared for conflict, lacking a military, FTL spacecraft , and the speed to react, but they would have their own tricks.

 

[Ryan_m_b]

Welcome to the forums Maiklas.

I don't think it's so hard as some of the above posters say, as it need not be a truly closed system

If he's going with realistic science then it's going to be pretty hard to build a sustainable ecosystem with a carrying capacity sufficient for the population. Whilst it doesn't have to be completely closed (waste could be dumped, resources harvested) a lot of the knowledge, techniques and technology is going to be the same. This set up is comparable to trying to set up self-sufficient colony on another planet; you get the resources of the planet but you've got to do a lot of work to use them to keep the ecosystem alive.

 

[twofish-quant]

The minimum complexity for a redundant, sustainable ecosystem is likely to be huge.

I'm not entirely convinced of that. If this is true, then we are going to be stuffed if we try to colonize Mars.

The best idea I can think of would be to investigate some of the most isolated ecosystems that can sustain humans and try to replicate them.

Submarines and spacecraft .

I wasn't using a spacecraft model because they aren't sustainable.

Now. But any spacecraft that goes out of Earth orbit has got to be sustainable for months at a time. If you have a Mars colony or something around Jupiter, it's got to be sustainable indefinitely.

Considering the goal here is the continued survival of the species I don't think this action of delaying the innevitable would help.

One thing to consider is that if the sun were going out, then it might not make much sense to stay on Earth at all. The missing element is energy. With enough energy anything is possible. So if the sun were going out, it might make more sense to relocate to Io where you have volcanos which are powered by Jupiter's gravity field. Or you could have hydrogen fusion generators with Jupiter giving an essentially infinite source of hydrogen.

Even getting as many people out of the Earth's gravity well as possible would be useful. If you stay in the Earth's gravity well, then you are trapped. Once you get as many people as possible into "deep space" then you can start colonizing as many asteroids and comets as you can to maximize the odds that someone is going to survive.

 

[mfb]

If science jargon is not your forte, don't try to explain it. Just have the brightness of the Sun diminish for "no reason". If heat takes a million years to escape from the core, then the core quenched a million years ago and now we're seeing the effect.

Well, this would be a slow effect, slightly reducing solar radiation over the timescale of hundred thousand of years. In addition, solar neutrino observations can directly measure the rate of fusion in the core.

We are talking about something happening decades in the future, and I would expect that a significant amount of working hours can be spent for preparation, assuming the society remains intact. I would expect that roboters can do a lot of mechanical tasks. If you can train a robot to replace one specialist, you can train the robot to replace 10000. Not with the same output as 10000 workers, of course, but you can simply copy the memory to "train" more robots. Those robots would need a significant infrastructure, but (at least in theory) they are able to maintain this, perhaps with the help of humans. You need years of practice for neurosurgery, but if you can build some parts of a car and have a good guide, you might be able to build other parts of it, too.

The alternative would be to implement everything low-tech. Design cars so simple that 10 humans can build them. However, I think this approach will be doomed the day the oxygen runs out, as burning fossil fuels would probably be the only heat/energy source for the whole environment. Fission or even fusion are too complex to maintain.

 

[twofish-quant]

Something to point out here is that some of the best science fiction assumes something weird happening and looks at the consequences rather than trying to figure out the cause. One thing that you can do is to say "the sun is going out, and no one knows why." The fact that no one knows why the sun is going out would have some interesting consequences.

The alternative would be to implement everything low-tech. Design cars so simple that 10 humans can build them. However, I think this approach will be doomed the day the oxygen runs out, as burning fossil fuels would probably be the only heat/energy source for the whole environment. Fission or even fusion are too complex to maintain.

Fission reactors would be probably be impossible to maintain, but radiothermal generators could be maintained with minimal skills. The trouble is that I don't know what the energy requirements would be. The energy output of RTG's have been low, but traditionally they have been intended for space use where there are weight requirements.

And I'm not even sure that it would be impossible to design a fission reactor that would be need minimal intervention. Natural managed to create one at Oklo, Gabon.

That actually would be a good place to start. How much *energy* does it take to keep a human alive and how much of that comes from the sun.

 

[Ryan_m_b]

I'm not entirely convinced of that. If this is true, then we are going to be stuffed if we try to colonize Mars.

Yup.

Submarines and spacecraft .

These are not sustainable isolated ecosystems. Once their food stocks are gone it's game over. Think more along the lines of an ecosystem that cycles from autotrophs to detritivores via enough animals to sustain a human population.

Now. But any spacecraft that goes out of Earth orbit has got to be sustainable for months at a time. If you have a Mars colony or something around Jupiter, it's got to be sustainable indefinitely.

By definition I'd say that a spacecraft is not sustainable. Sustainability is linked to recycling, a biosphere can recycle it's resources potentially indefinitely with constant energy input. A spacecraft cannot, a colony would need to (else it's a dependant outpost).

One thing to consider is that if the sun were going out, then it might not make much sense to stay on Earth at all. The missing element is energy. With enough energy anything is possible. So if the sun were going out, it might make more sense to relocate to Io where you have volcanos which are powered by Jupiter's gravity field. Or you could have hydrogen fusion generators with Jupiter giving an essentially infinite source of hydrogen.

I don't see why one couldn't just construct solar panels across swathes of Earth's now frozen surface or use fusion (or any other energy source) on Earth. Moving to space would make the whole endevour hugely more complicated and expensive through the added headache of having to get it there (or designing and shipping equipment to build it all there).

Even getting as many people out of the Earth's gravity well as possible would be useful. If you stay in the Earth's gravity well, then you are trapped. Once you get as many people as possible into "deep space" then you can start colonizing as many asteroids and comets as you can to maximize the odds that someone is going to survive.

I don't see why moving to space would change any chance of survival. You're going to need precicely the same resources and innovations only if you try for space you have to make it all work there or ship it there.

 

[twofish-quant]

These are not sustainable isolated ecosystems. Once their food stocks are gone it's game over. Think more along the lines of an ecosystem that cycles from autotrophs to detritivores via enough animals to sustain a human population.

I don't see food as a big problem. The fact that we digest plants and vegetable matter is an accident of evolution. It's possible to get all your nutrition injected via an IV, and there are people who end up living for years at a time with all their nutrition supplied that way.

http://en.wikipedia.org/wiki/Parenteral_nutrition

I don't see why one couldn't just construct solar panels across swathes of Earth's now frozen surface or use fusion (or any other energy source) on Earth.

Solar panels won't work. No sun. The thing about Jupiter is its this huge gravity engine which leaks out energy in several different ways, which might be collectable.

Moving to space would make the whole endevour hugely more complicated and expensive through the added headache of having to get it there (or designing and shipping equipment to build it all there).

Right. But it's best to do it when the lights are still shining.

Also a lot depends on when the lights start to go out. If the sun starts to fade when we already have a solar system infrastructure in place, then what we can do is to use solar power satellites to store as much of the energy of the sun as we can, so that we can tap into it once the lights go out.

I don't see why moving to space would change any chance of survival. You're going to need precicely the same resources and innovations only if you try for space you have to make it all work there or ship it there.

More options. Also with the larger planets you get a source of energy. There's also the "now or never" situation. Even in the best case scenario I can't imagine an post-sun Earth based civilization *ever* getting the ability to go into space, and if everyone stays on earth, then it's going to be the end sooner or later.

The other thing that could be done is genetic engineering. You could start engineering people that would be most likely to survive the lights going out.

 

[Ryan_m_b]

I don't see food as a big problem. The fact that we digest plants and vegetable matter is an accident of evolution. It's possible to get all your nutrition injected via an IV, and there are people who end up living for years at a time with all their nutrition supplied that way.

http://en.wikipedia.org/wiki/Parenteral_nutrition

I think you're mistaking the product for the process here. The nutrients that go into IV still have to be produced like regular food. I don't know too much about IV but if it's anything like culture medium then it isn't defined either which is an extra barrier to any artificial synthesis (and if we could synthesise such things we could use it to make in vitro foods if we wanted).

Solar panels won't work. No sun. The thing about Jupiter is its this huge gravity engine which leaks out energy in several different ways, which might be collectable.

Geothermal or nuclear then. I don't see Jupiter as being a more attractive option given then sheer cost involved in any space endeavour (as well as the extra R&D needed).

More options. Also with the larger planets you get a source of energy. There's also the "now or never" situation. Even in the best case scenario I can't imagine an post-sun Earth based civilization *ever* getting the ability to go into space, and if everyone stays on earth, then it's going to be the end sooner or later.

Why would it end on Earth sooner or later? Also I don't see any realistic way that this could be accomplished. I know that sounds strange considering the topic of this thread but hear me out: proposing that mankind has the ability to build sustainable underground cities that can house all the ecology, industry and societies we need is one thing considering that all of those things are here on Earth but considering doing it in space (where we would have to seriously ramp up our in-situ resource allocation and fab lab technologies) just adds orders of magnitude of difficulty.

The other thing that could be done is genetic engineering. You could start engineering people that would be most likely to survive the lights going out.

Perhaps though that's so far into the realms of science fiction there isn't much to discuss. Right now if we tried we might be able to swap one allele for another but significant phenotypic engineering is way out there.

 

[Czcibor]

When I was playing with a simulation where merely putting an object of size of an underweight star was making havoc in our system. (actually in the simulation that I run the mess wasn't immediate) My idea?

Apocalypse rider: burnt out brown dwarf - massive enough, popular enough, damn hard to detect

Way: it crosses the system and immediately destabilizes orbits. However, the doom on Earth is not immediate it first is moved to much higher orbit/more eccentric. Later it is ejected from the system by interactions with Jupiter.

(so you can get a few decades in which the situation is degrading somewhat)

Possible energy sources: geothermal and nuclear. Iceland becomes surprisingly hospitable ;) Nuclear power plant - the safest place to live ;)

Political system - who got saved? Military? A few rich people and those who they hired? Democratic gov selected? By random from all citizens? By some meritocratic exam?

I would not worry too much about carbon dioxide. If the planet got colder it would freeze at places where temperature would be below -78C.