Was there enough time for a planet like earth to exist long before earth?

[Edtharan]

It is always the most adventurous and entrepreneurial that do so. Motive comes from those factors, rather than dire need.

These motives are sporadic and would therefore slow expansion down. If each colony needed to exhaust their resources before moving on then it could take millions of years to go from one system to another. Also if you need adventure or religious motivations then these would also slow down the expansion.

 

If a species is to expand throughout the galaxy they will need a constant motivation to expand. Population pressure is one. Any breeding that results is steady population growth will eventually out strip the ability of a colony and so expansion would then take place. Even this leaves a small window of opertunity for expansion as an increasing population will need more resources to survive and so the limit on the rate of resource aquisition will eventuall outstrip this, making expansion too costly.

 

This short window of opertunity will also slow down the rate of colonization.

 

The tramline system of faster-than-light is immensely cheaper and it is relatively cheap to build a ship to do that. However, due to the special spacial circumstance in the novel, the Moties couldn't use it (they came out inside a star). But we are discussing a universe where faster-than-light is completely impossible and species are restricted by physics to sublight. In that situation, the economic situation facing the Moties would apply to ANY species unable to control their population.

In the Novels (the original and the sequal) they discuss what would happen if the Moties got out or were able to use the FTL drives. Thye talk about the fact that the population growth would exceed the rate of expansion from the core systems and so war would break out. This war would then also spread to the outer colonies, and would reduce the rate of expansion.

 

There may be many reasons for expansion, but there are also a lot of things that would slow down the rate of expansion, may be even to the point of 0 expansion or even contration.

[Sayonara]

It seems to me, having reviewed the thread, that SkepticLance is making an argument from incredulity.

 

There is no "certainty" here just because of the large figures involved.

 

We can reasonably predict a large number of heads or tails during any series of billions of coin tosses, but that is because we understand the nature of coins and the factors involved that control the probabilities.

 

We lack that understanding where galactic ecology is concerned.

[lucaspa]

lucaspa.

You are niggling me because I a suggesting a range of possible motives for going interstellar. We are talking about possible a million species and 2 billion years. There are possibly thousands of different motives for going interstellar. Any of them will do.

 

What you are doing is changing the argument in the face of falsifications. Another way of putting it is that you are introducing ad hoc hypotheses to try to save your hypothesis. Remember' date=' your claim depend not just on going "interstellar", but having a [i']sustained, continued [/i]colonization program using sublight transportation such that one of the species would have reached earth.

 

You need a motive that gives you continued colonizations/explorations. So far none of the suggested motives have withstood critical examination to give you the certain, sustained colonization. Accept that. Yes, you can maintain possibility, but the arguments against that are just as strong or stronger. Conclusion: there could indeed be a million technological species in the galaxy but, if we are limited to less than 0.5c, there are very good reasons why none of them have made it to earth.

 

the data does say that an alien species never made a LONG TERM -- billions of years -- colonization of earth. If they had, they would still be here! BUT, it doesn't discount a complete colonization of several million years a billion years ago[/i]

 

For God's sake, lucaspa. If a species was on Earth one million years, it would leave so much garbage that we would be living in their land fills!

 

You took out a key phrase. I put it back in italics. And why would those landfills be on the surface? How much of our planet has rocks from a billion years ago on the surface? C'mon, do some research and give us some data! Yesterday the news was that a new oil well in the Gulf of Mexico had come online. It was 20,000 feet below the surface. So, yes we could be living on their landfills -- but they are 20,000 feet below us.

 

OR ... those landfills have already been eroded. 500 million years ago the Appalachians were 40,000 feet tall. What do you think happened to them?

 

Yet we have not found a single artifact. And please don't throw crackpots at me. Their hypothetical artifacts would not fool a five year old. Right now, we have NO alien artifacts.

 

I would think you would leap at those artifacts, since they are support for visitation. However, would the artifacts still be here even a million years afterward. I've already pointed out methods of degradation. What artifacts do you think would be immune and would last for a million years, much less a billion?

 

Let's forget moties. It is fiction and thus irrelevent to the discussion.

 

But the economic, social, and biological consequences of unrestrained reproduction are not fiction. Think of the novels as a thought experiment and speculation. After all, it was YOU who pointed out that we are engaging in speculation. So Niven and Pournelle's speculation based on economic and biological realities are relevant. You just don't want them to be because those consequences refute your conclusion. That's not a good enough reason.

 

You proposed population pressure as the prime motive for colonizing the galaxy using ships at 0.2c. But the speculation is that such population pressure is more likely to lead to cycles of trying to feed the population followed by catastrophic war for resources, and then back to barbarism. Now, instead of trying to ignore the speculation, try to show why it is inaccurate.

 

However, I am suggesting a species that controls its numbers when it must, and multiplies when it can. Are you telling me that such a species is impossible when we talk about a millions species over 2 billion years. I don't think so.

 

I'm saying that if such a species exists, then economics will ensure that it controls its population before it gets critical and will remove the motive for colonization. This is where the studies on humans -- who fit your profile -- come in. Increasing wealth causes control of population -- because the individuals "must" control their population to retain their wealth. And a civilization technologically advanced enough to make the generation ship you propose will be wealthy. Thus, already controlling their population. And there goes your motivation. The planet is not overcrowded and there is no population pressure for colonization.

 

Now, you propose a 50 years hop of 4 light years. BUT, we don't know that Alpha Centauri has planets. Is it even theoretically possible to detect an earth-like planet at that distance? I doubt it, but you can do the research to show me wrong. So, the ship can't just be engineered for that hop, can it? If Alpha Centauri doesn't have planets, then they have to keep going ... for they don't know how long. You can't engineer for that. You have to control population.

 

The way to determine habitable planets would be to send a probe. That's at least 50 years out and 4 years transmission time back ... assuming nothing bad happens to the probe. So, 54 years before launch of the probe until you even know if you can launch the colonization mission. Economically, there is no use even building a ship until the info is back and is positive. So now you have construction time. By this time, any political or social motivation for colonization has probably gone away.

[lucaspa]

These motives are sporadic and would therefore slow expansion down. ... Also if you need adventure or religious motivations then these would also slow down the expansion.

 

If a species is to expand throughout the galaxy they will need a constant motivation to expand. Population pressure is one. ... Even this leaves a small window of opertunity for expansion as an increasing population will need more resources to survive and so the limit on the rate of resource aquisition will eventuall outstrip this' date=' making expansion too costly.[/quote']

 

SkepticLance keeps ignoring economics. You make the same point I've been making: sublight generation ships are expensive. And by "expensive" you are I are talking resources. Money is simply a convenient way of tracking resources. When resources (supply) are limited, then the price of those resources goes up. Basic supply and demand. As you pointed out, as population increases, you get calls to use the resources for demands other than a starship. We see that here on earth today: people want to stop the space program and use the resources to improve life on this planet.

 

As you noted, this means that a species is going to have a small window in time where there are spare resources to build a starship. If for any reason (such as political division like we have on earth), they don't build the starship, then they will lose the capability.

 

This short window of opertunity will also slow down the rate of colonization.

 

In the Novels (the original and the sequal) they discuss what would happen if the Moties got out or were able to use the FTL drives. Thye talk about the fact that the population growth would exceed the rate of expansion from the core systems and so war would break out. This war would then also spread to the outer colonies, and would reduce the rate of expansion.

 

Yes, and that was with an FTL drive. Unless the FTL drive was instantaneous to anywhere, even FTL has a finite speed. I discussed this in a reply to your previous post that the inner worlds could not ship their excess population out past the colony worlds. So you either have war with the colony worlds for settlement or the inner worlds collapse and the population (and civilization) is drastically reduced thru war and/or starvation. Now, since it is known that the inner words are inhabited and their location is known, it would be easier for the outer colony worlds to ship their population back to the inner worlds rather than expand outward.

 

In that case, you get an optimum sphere size of colonized worlds and continual shifting of population within the sphere -- which both you and I have pointed out before, but SkepticLance ignored.

 

There may be many reasons for expansion, but there are also a lot of things that would slow down the rate of expansion, may be even to the point of 0 expansion or even contration.

 

Right. As far as I can see, none of SkepticLance's reasons for expansion are inevitable. All of them have counteracting processes that would eliminate the motive/expansion or reduce it to a crawl such that the expansion has not gotten even close to earth yet.

[swansont]

Now, you propose a 50 years hop of 4 light years. BUT, we don't know that Alpha Centauri has planets. Is it even theoretically possible to detect an earth-like planet at that distance? I doubt it, but you can do the research to show me wrong.

 

Theoretically, yes. Practically, almost. A colleague is getting ready to deploy a device that should be able to do just that, and has already used a lower-resolution apparatus to detect larger objects http://adsabs.harvard.edu/abs/2005AAS...207.6813H

 

Larger extrasolar planets have already been detected, of course.

 

addendum (just got an email pointing to this): http://www.centauri-dreams.org/?p=806 link to paper: http://arxiv.org/abs/astro-ph/0608489

 

"As the paper points out, an Earth-sized planet transiting such a star will block about 1 percent of the stellar flux from that star. If in a habitable 3.85-day orbit, the planet will make a transit that lasts about forty minutes. These are workable numbers, as the paper says:"

[lucaspa]

Theoretically' date=' yes. Practically, almost. A colleague is getting ready to deploy a device that should be able to do just that, and has already used a lower-resolution apparatus to detect larger objects http://adsabs.harvard.edu/abs/2005AAS...207.6813H

 

Larger extrasolar planets have already been detected, of course.

 

addendum (just got an email pointing to this): http://www.centauri-dreams.org/?p=806 link to paper: http://arxiv.org/abs/astro-ph/0608489

 

"As the paper points out, an Earth-sized planet transiting such a star will block about 1 percent of the stellar flux from that star. If in a habitable 3.85-day orbit, the planet will make a transit that lasts about forty minutes. These are workable numbers, as the paper says:"[/quote']

 

Thank you. This gives you an earth-sized planet. But not necessarily an earth-like planet. After all, Venus is approximately earth-sized, but hardly earth-like. Ditto for Mars.

 

Now, unless you go there -- either in person or with a probe -- can you know ahead of time that the planet is going to be habitable?

[swansont]

Thank you. This gives you an earth-sized planet. But not necessarily an earth-like planet. After all' date=' Venus is approximately earth-sized, but hardly earth-like. Ditto for Mars.

 

Now, unless you go there -- either in person or with a probe -- can you know ahead of time that the planet is going to be [i']habitable[/i]?

 

 

Martin's got some links about that in another thread. It appears we're getting to the point where we can tell. http://www.scienceforums.net/forums/showthread.php?t=22722

 

I think the combination of determining size, mass and orbit get you a significant fraction of the information you need.

[Edtharan]

One way of determineing if a planet is habitable is to use a large interferometer. The best places for this (for Earth) would be in one of the L points. This gets it far enough away from earth to redeuce any interfereance from here and the L piints are fairly stable.

 

Using a base line of a few tousand kilometres you could get a decent resolution that would be able to detect planets. The larger the base line the better, and if it is large enough, you should be even able to map the surface in good detail.

 

However the further away the plaent is the less detail you will see, so this would only be useful for nearby planets (so no long distance jumps) and resources would be needed to build these telescopes (but they would be fairly cheap compared to sending a probe or going there with a crewed mission). It would be posible for us to build such a system now if we could pull the resources (not just money, but time and population, experience, etc) together. We could do this today (well 5 to 10 years or so).

[lucaspa]

Martin's got some links about that in another thread. It appears we're getting to the point where we can tell. http://www.scienceforums.net/forums/showthread.php?t=22722

 

I think the combination of determining size' date=' mass and orbit get you a significant fraction of the information you need.[/quote']

 

I've looked at the Science paper. It tells us HOW an earth-like planet could form in a system with a hot Jupiter-sized planet close to the sun. But it doesn't say it will form or any indication that we can detect that a planet is, indeed, earthlike.

 

 

One way of determineing if a planet is habitable is to use a large interferometer. The best places for this (for Earth) would be in one of the L points. This gets it far enough away from earth to redeuce any interfereance from here and the L piints are fairly stable.

 

Using a base line of a few tousand kilometres you could get a decent resolution that would be able to detect planets. The larger the base line the better' date=' and if it is large enough, you should be even able to map the surface in good detail.

 

However the further away the plaent is the less detail you will see, so this would only be useful for nearby planets [/quote']

 

http://planetquest.jpl.nasa.gov/technology/technology_index.cfm Typical of articles on interferometry I've gathered. It does allow better resolution but not nearly the magnification you would need to map an eath-sized planet 4 light years away. Nor would it tell you the mean temperature or the composition of the atmosphere from what I can see. Even if you get a map of the continents of an earth-sized planet and see that it has liquid water, what happens if there are a lot of volcanic eruptions and the atmosphere has toxic levels of sulfur dioxide.

 

As far as I can tell, you still need a probe.

[lucaspa]

Martin's got some links about that in another thread. It appears we're getting to the point where we can tell. http://www.scienceforums.net/forums/showthread.php?t=22722

 

I think the combination of determining size' date=' mass and orbit get you a significant fraction of the information you need.[/quote']

 

From the article:

"We find that 54 out of 158 (34%) giant planetary systems in our sample permit an Earth-like planet of at least 0.3 M to form in the habitable zone (Fig. 3). The fraction of known systems that could be life-bearing may therefore be considerably higher than previous estimates (30). "

 

Now, that increases the possibility of earth-like planets. But it doesn't guarantee any earth-like planets in any given system or that a planet of the appropriate size is going to be habitable. After all, they also note:

 

"The surviving planets can be broken down into three categories: (i) hot Earth analogs interior to the giant planet; (ii) "normal" terrestrial planets between the giant planet and 2.5 AU; and (iii) outer planets beyond 2.5 AU, whose accretion has not completed by the end of the simulation. Properties of simulated planets are segregated ... Both the hot Earths and outer Earth-like planets have very high water contents [up to >100 times that of Earth (28)] and low iron contents compared with our own terrestrial planets. ... The high water contents of planets that formed in the habitable zone suggest that their surfaces would be most likely covered by global oceans several kilometers deep. Additionally, their low iron contents may have consequences for the evolution of atmospheric composition "

 

The article ends with a hope that missions inside the solar system can detect Earth-like planets. I've gone to JPL and looked at the Terrestrial Planet Finder pages. It's an idea that MAY be possible. It depends on being able to do a spectral analysis of a planet's atmosphere from light years away. But I don't see any hard data that this can be done.

http://tpf.jpl.nasa.gov/mission/mission.html

 

They at least know what they want to look for:

http://tpf.jpl.nasa.gov/earthlike/earth-like.html

 

But can they get those spectra?

 

 

"Upcoming space missions such as the National Aeronautics and Space Administration's Kepler and Terrestrial Planet Finder and the European Space Agency's COROT and Darwin will discover and eventually characterize Earth-like planets around other stars."

[Reaper]

I know this is an old thread, but any talk of the nature of extra-terrestrial civilizations has always interested me. Plus, I don't want to start a new one since there's a bunch of good discussion here...

 

I'm going to add my two cents to this and try to rekindle discussion on this topic:

 

For one, I do think that the Dyson Sphere (or something similar) is a pretty strong argument for why we may not see vast galactic empires or large scale interstellar colonization if we assume that FTL travel isn't possible (and even if it is, I read somewhere that such technology if it could be, such as making a wormhole for example, would take up so much energy that it probably wouldn't be practical).

 

I read somewhere, and I'll try to find the source again (I think it was in a book though), that the solar system possesses enough resources to support a few quadrillion human beings, assuming that the population does ever get that high, and can do so for hundreds of thousands or millions of years. Of course, it is probably unlikely that our population will ever get that high, which of course means that the resources in our own solar system are virtually inexhaustible. As well, our own sun produces about 4 x 10^33 erg/sec, and will continue to produce a vast amount of energy for billions of years. So with this alone there probably wouldn't be a purely economic reason for going out into the galaxy. Of course, exploration (scientific or otherwise) of the galaxy would probably occur via robotic probes.

 

If colonization of the galaxy were to occur, the reasons would probably be different other than for purely economic, political, etc. For example, some people might want to leave the solar system out of adventure (as had been mentioned earlier), or out of religious reasons, or political, or any number of reasons; if one can be found, then it will probably occur no matter how illogical or irrational or unscientific they may be. It is entirely possible for a civilization to go out just for the heck of it, or for sheer thrills (humans, for example, have been known to go off on lengthy conquest campaigns even when it was unnecessary...). Of course, economics would absolutely need to be taken to account (e.g. possible multi-generational ships).

 

Now, I have read various possible explanations of the Fermi Paradox, and the idea that a civilization would be able to colonize an entire galaxy in a cosmological blink of an eye. Even though it may technically be possible to do that, assuming there was a constant drive, I don't necessarily believe that it could happen that fast. For one, traveling around in a multi-generational ship is probably going to make who ever is on it very weary, and once they reach their destination they will probably stay there for an indefinite period of time. And then of course it is possible (and most likely IMO) that a given civilization that colonizes and starts to exploit their solar system's resources will only send a few (we will say less than 100 or 1000, obviously more than one will need to be sent in order to ensure that at least some will be successful) of those ships out into the galaxy should they ever decide invest in them. And then of course, there is no telling whether the colonists of those star systems will decide to invest in continuing colonization of the galaxy after they establish themselves. Also, once they establish themselves, whatever civilization that flourishes (or not) will probably go a different route then it's parent civilization (some may be expansionist, while others may not, or some may even die off). This and other factors of course would probably slow the expansion of a given civilization by a great deal and it is entirely possible that they may only go out to a limited number of star systems before they stop expanding, and so even after a billion years they may never colonize the entire galaxy. For all we know, the colonization effort may have begun 2 billion years ago (to pick an arbitrary number that has been flung around alot in this thread) by an alien civilization, but they still probably haven't finished colonizing the galaxy as of yet (or may have stopped after some point).

 

============================

 

Another idea that has also been flung around in this thread is the idea that they might not colonize planets at all, which I find interesting. And, after thinking about it, it probably would make a lot more sense. If we take a look at our own plans for colonizing for example, I know that the only bodies or planets in the solar system that has been seriously considered for possible human colonization are Mars and Titan. Venus, for example, will probably never be colonized. And even with a planet like Mars there are already formidable problems facing us such as a hostile environment (you will only survive for tens of seconds on Mars without a spacesuit), radiation, etc. It seems to me that planets are pretty much a big hassle, and that it is probably easier to just create an artificial environment on an asteroid or a moon or something. As we all know, asteroids, comets, and moons have the great advantage of having extremely low gravity (and therefore wouldn't require nearly as much resources and energy to exploit them) and have a great many valuable resources; asteroids have metals and other useful elements, comets have water and organic material (and therefore can potentially sustain life), and moons at least provide a solid base on which potential colonists to other solar systems can inhabit. Also, gas giants might probably be much better for interstellar travelers than planets like Earth (e.g. for resources or energy extraction, or for propelling themselves to get around their star system via gravitational assist). This of course would give rise to a sort of nomadic lifestyle by a given civilization. So, maybe there have been several visitors to our solar system over the past billion years, but they may have decided to stay around the asteroid fields, the gas giants, and the Kupier Belts rather than settle on Earth.

 

Another thing that I've been thinking about is that maybe interstellar travelers would value places like black holes, nebula, or supernova remnants, much more than star systems. Black holes, for example, can provide a huge amount of energy and resources for a given interstellar traveler to base their colony off of. Nebula, of course, have a very large amount of elements and other resources, in addition to having young stars. So maybe, these civilization do go out, but they don't settle on small rocky planets like Earth, but rather go to black holes. I know that black hole cities have been hypothesized, and a colony or civilization around one will probably last for an indefinite period of time.

 

My two cents, you can feel free to pick them apart if you wish...

 

 

 

===================================

 

More food for thought...

 

Speaking of theoretical civilizations in science-fiction, I do have a couple of examples of races that do not colonize planets, both from the game Homeworld and its sequels:

 

The Vaygr are a warrior clan originally from Vay, an isolated planet in the eastern fringes of the galaxy. The discovery of early and inefficient hyperdrives enabled these warriors to travel and raid widely across their sector of space. Always a nomadic race, the strongest warlords brought groups together into crusades. A Vaygr crusade is entirely independent. The build capacity of their Motherships (Also known as flagships) combined with the resource harvesting of their individual craft enable them to live self sufficiently in space. Communication between separate Vaygr crusades is minimal.

 

and

 

The Bentusi are an enigmatic race of highly advanced, nomadic traders. Calling themselves The Unbound, the Bentusi have no known leader and are all cybernetically integrated into their ships (much like Karen S'Jet but believed to be much more advanced). The Bentusi are a very ancient, wise race who do not claim any planet for themselves, instead opting to live exclusively among the stars. It would probably be impossible for the Bentusi to even survive outside of their ships, since they are physically connected to them....

 

It seems to me that if this is the preferred methodology of galactic colonization (preferring space and small asteroids or black holes to planets) among species, then it is entirely possible that there does exist a vast galactic empire right at this moment, but don't bother with planets such as Earth. And IMO these type of civilizations similar to the ones above are entirely possible and plausible, even without FTL technology. So, that might be yet another reason as to why we don't seem to find any evidence of interstellar aliens having visited Earth. Indeed, basing their civs on nomadic lifestyles such as the ones described above could certainly have many advantages and benefits as opposed to colonizing planets (e.g. low maintenance, chances of being wiped out by a comet or a supernova would certainly drop dramatically, probably close to 0, etc).

 

Also the reason I put italics around the communication part is because there is the possibility (IMO more than likely) that once they do begin to go out they will probably not spend that much time and resources to maintain communications with their home star system, especially if FTL travel is indeed not possible (why would they? They are after all hundreds of trillions of miles away...). And I have read about this sort of scenario in my readings on galactic colonization, where, say 10-20 million years from, now a group of creatures that were descended from humans may one day travel to Earth and probably not recognize that it was indeed their home world, and if there is still a civilization there they may see it as completely alien....

[SkepticLance]

To Lockheed

 

Lots of nice ideas in your post, and I tnd to agree with most of them.

 

A couple of quibbles, though.

 

1. If you are discussing a Dyson Sphere, or even a Ringworld, there is a major technological problem. Larry Niven published his book 'Ringworld' without even realising this occurred, and had to be told by some of his readers. That is, a Dyson Sphere or Ringword is not an orbital structure. Thus it has no orbital stability. It will move through space independently of the star it surrounds.

 

This means that it will require a separate mechanism for maintaining its position relative to its parent star. Otherwise, it is only a matter of time for a sphere before the star simply moves right through the sphere and on into outer space. Or for a ring, the star would probably move away, and leave the ring spinning in the deep cold of space. If you bear in mind that the ring or star would weigh as much or more than our entire solar system put together, the mind boggles at the mechanism that would continually adjust its position relative to the star.

 

2. Why should a civilisation want to concentrate itself on moons? The gravity would probably be too low to maintain good health, and it is limiting in terms of travel. Full gravity can be achieved by a spinning habitat in space, which would be able to move freely about the entire solar system and beyond. Raw materials can be harvested from anywhere.

 

Bearing this in mind, my own picture of the distant future human civilisation is not a sphere or ring, but a cluster. A trillion habitats in orbit about a star. No problem adjusting position. Full gravity. And mobility. In fact, assuming advanced nuclear fusion power generation, why would they need a sun at all?

 

Any time the peoples of a habitat, which might be a space city of many millions, want to move, they fire up the ion drive and slowly accelerate away.

 

Such a civilisation would be infinitely mobile throughout the galaxy, only limited by their technology and the speed of light.

[Reaper]

1. If you are discussing a Dyson Sphere, or even a Ringworld, there is a major technological problem. Larry Niven published his book 'Ringworld' without even realising this occurred, and had to be told by some of his readers. That is, a Dyson Sphere or Ringword is not an orbital structure. Thus it has no orbital stability. It will move through space independently of the star it surrounds.

 

If we are going to assume a full blown Dyson Sphere (where it is all closed off), then it may not need to orbit its star at all; all it would have to do is move at the same speed relative to its star. All the bodies in our solar system including the sun are moving at the same speed, more or less, around the center of the galactic core. Though that doesn't mean that it doesn't have problems in general; for instance I'm sure a full blown Dyson Sphere will probably cause some gravitational issues around its own star, as well as some other nearby star systems or bodies near the star system...

 

 

This means that it will require a separate mechanism for maintaining its position relative to its parent star. Otherwise, it is only a matter of time for a sphere before the star simply moves right through the sphere and on into outer space. Or for a ring, the star would probably move away, and leave the ring spinning in the deep cold of space. If you bear in mind that the ring or star would weigh as much or more than our entire solar system put together, the mind boggles at the mechanism that would continually adjust its position relative to the star.

 

Well, with a ring system, you would definitely need some major orbital adjustments and other mechanisms, so I do agree with that point. But, its not so much because the star would move out of the ring; it's more like that because without any, the ring itself would probably get pulverized by the star's own gravity! One only has to look at what happens when a large body gets too close to a gas giant for example.

 

 

2. Why should a civilisation want to concentrate itself on moons?

 

I'm not arguing that a civilization should, but that settling on moons (or other small bodies) instead of planets would probably be better (assuming that they find moons about as small as our own solar system). Low gravity bodies and worlds does bring in a great deal of benefits in terms of energy requirements, colonization/exploration/exploitation of its new star system (don't need nearly as much fuel to go from one body to another), some form of radiation protection, and most of all I would imagine that it is much more adaptable or survivable. We don't know the effects of high gravity on the human body, or any other life form, as of yet. We do have quite a bit of data on how Earth organisms fare in microgravity though, and not all of them are as disadvantaged as we are; the reason it's bad for us humans is because our bones weaken by losing calcium and muscle atrophy happens quite quickly.

 

Likewise I also suggested that gas giants would be of much better use than planets like Earth or Mars sized ones, not necessarily for colonization but for resource and energy purposes and for propulsion of any future space craft that will travel around their local star system. And then of course, there are nebula, black holes, etc.

 

 

The gravity would probably be too low to maintain good health, and it is limiting in terms of travel. Full gravity can be achieved by a spinning habitat in space, which would be able to move freely about the entire solar system and beyond. Raw materials can be harvested from anywhere.

 

Bearing this in mind, my own picture of the distant future human civilisation is not a sphere or ring, but a cluster. A trillion habitats in orbit about a star. No problem adjusting position. Full gravity. And mobility.

 

I think its safe to assume that a civilization sufficiently advanced enough to travel around its own solar system and to travel to other star systems will have already transcended such limitations such as the need for artificial gravity. IMO, if we can get rid of the need for that, then it would make living in space far easier than it is right now, and far less energy intensive. Genetic manipulation that will come about in this century will certainly help us with space colonization and overcoming the several challenges that we will face.

 

In fact, assuming advanced nuclear fusion power generation, why would they need a sun at all?

 

You are kidding, right?

[SkepticLance]

To Lockheed

 

Your post is interesting and intellectually stimulating. Thank you.

 

Dyson sphere. The fact that the Dyson sphere will be moving, relative to the galaxy, at more or less the same speed and direction as its star will only slow down the problem. Without an active positioning system, sooner or later any minor differences will lead to the star approaching closer to one side than the opposite. That, inevitably will, in time, lead to disaster.

 

Your point about an advanced civilisation not needing gravity is a good one. You convinced me. After thinking about it, I realised that the future human society could apply genetic engineering and create a human that does not suffer health problems in zero G.

 

My point about not needing a sun was serious. Any human society will need an abundant source of energy. However, that might be internally generated inside the space habitat. A deuterium based fusion power plant would need water as feed-stock. If we take into account what we think we know about the Kuiper Belt, it seems likely that there is abundant mass at enormous distances from suns - possibly even in interstellar space. I could imagine a habitat moving from muddy snowball to muddy snowball way out there, mining the water and minerals, and never needing to approach any sun.

[lucaspa]

Though that doesn't mean that it doesn't have problems in general; for instance I'm sure a full blown Dyson Sphere will probably cause some gravitational issues around its own star, as well as some other nearby star systems or bodies near the star system...

 

It shouldn't. After all, the material that composes the Dyson sphere would have to be the matter that was already in that solar system. The planets would have to be used to get the matter to make the Dyson sphere. So the mass is the same.

 

Well, with a ring system, you would definitely need some major orbital adjustments and other mechanisms, so I do agree with that point. But, its not so much because the star would move out of the ring; it's more like that because without any, the ring itself would probably get pulverized by the star's own gravity!

 

I suggest you read Niven's later Ringworld novels. It turns out that the Ringworld "wobbles" and, without correction, eventually the ring will be so eccentric that it will brush the sun.

 

Of course, a problem with a Ringworld is that you need a VERY strong material so that it is not torn apart by its own motion. Niven, since he is a science fiction writer, invented "scrith" and let it go with that. In the real world, we don't have a material nearly that strong.

 

When you build a Dyson sphere or a ringworld, you have to clear out ALL the other matter in the solar system. Otherwise a stray comet or piece of rock pokes a hole and you lose all your atmosphere. Even then, stray interstellar junk has the capability of hitting the sphere or ring. This is also a problem with Skeptic's "habitats". And a reason they might not leave their own solar system. Once in interstellar space, they are vulnerable to any debris around. Relative velocities are such that collisions would be catastrophic, especially when you are a couple of light years from help or a place you can evacuate to.

 

We do have quite a bit of data on how Earth organisms fare in microgravity though, and not all of them are as disadvantaged as we are; the reason it's bad for us humans is because our bones weaken by losing calcium and muscle atrophy happens quite quickly. ... I think its safe to assume that a civilization sufficiently advanced enough to travel around its own solar system and to travel to other star systems will have already transcended such limitations such as the need for artificial gravity. Genetic manipulation that will come about in this century will certainly help us with space colonization and overcoming the several challenges that we will face.

 

The effects extend far beyond that: http://jap.physiology.org/cgi/content/full/89/1/379

http://www.busoc.be/en/research/microgravity/humanphysiology.htm

 

There are cardiovascular problems and a decrease in red blood cells, for example. In the long term, that loss of bone is going to show up in neural problems. Calcium is extremely important in nerve function and the plasma calcium levels are VERY strictly regulated. Bone plays a huge role in the fine tuning of plasma calcium levels. Lose bone in prolonged microgravity and the nervous system is going to start degenerating over time, also.

 

So, no, I don't think civilizations would use genetic engineering to modify themselves so extensively. Such an extensive makeover would not only make them a new species, but at least a new genus. We wouldn't.

We would think we would lose something essential to being "human" in the process. Instead, we try to compensate by technology.

 

BTW, we are never going to be as smart as natural selection. That's why we use natural selection when the design problem is too tough for us! Genetic engineering ourselves is a very bad and stupid idea. Better to use technology.

[Reaper]

It shouldn't. After all, the material that composes the Dyson sphere would have to be the matter that was already in that solar system. The planets would have to be used to get the matter to make the Dyson sphere. So the mass is the same.

 

It's mass is the same, but the gravitational pull of an object is also dependent on it's density and size. So, there would indeed be some gravitational problems that you would have to account for when engineering something like a full-blown Dyson Sphere.

 

I suggest you read Niven's later Ringworld novels. It turns out that the Ringworld "wobbles" and, without correction, eventually the ring will be so eccentric that it will brush the sun.

 

I have read one of them. They are very good novels too, though some of the science is a bit sketchy in them.

 

In the real world, we don't have a material nearly that strong.

 

None that we know of that is .

 

Even then, stray interstellar junk has the capability of hitting the sphere or ring. This is also a problem with Skeptic's "habitats". And a reason they might not leave their own solar system. Once in interstellar space, they are vulnerable to any debris around. Relative velocities are such that collisions would be catastrophic, especially when you are a couple of light years from help or a place you can evacuate to.

 

That is true. To live in space or to travel between stars, or build a Dyson Sphere, or whatever, there would certainly be some problems they would have to overcome.

 

Which does mean, of course, if they have managed to solve them, would be yet another reason for why extraterrestrials may not settle on Earth, or on large rocky bodies similar to it, simply because planets would be too much of a hassle, especially with the atmosphere they might have to deal with and a relatively high gravitational pull compared with smaller bodies such as asteroids or small moons.

 

As for Skeptic's habitats, I do agree that they would be problematic if they decide to stay on one for an indefinite period of time.

 

 

So, no, I don't think civilizations would use genetic engineering to modify themselves so extensively. Such an extensive makeover would not only make them a new species, but at least a new genus. We wouldn't.

We would think we would lose something essential to being "human" in the process. Instead, we try to compensate by technology.

 

Maybe most humans wouldn't, but who's to say that an advanced alien civilization won't either? Certainly their ideologies or religions or ethics will be radically different from ours. And as for humans, there is still transhumanism; Even if a small minority end up supporting such radical changes in the far future, that is really all that is needed for them to become the dominant species or whatever in space; to use natural selection, such humans that much adapted would be far more likely to survive than those humans who aren't, and therefore would be more likely to reproduce, and less likely to go extinct .

 

BTW, we are never going to be as smart as natural selection. That's why we use natural selection when the design problem is too tough for us! Genetic engineering ourselves is a very bad and stupid idea. Better to use technology.

 

And that I do agree with that. I wasn't proposing that we rely solely on genetic manipulation, but that it will certainly help us in being able to adapt to the outer space environment or other planets. Certainly, if we can slow the rate at which our health deteriorates via biotechnology to the point where we can last for even a couple of decades in space without having to go back to Earth or a planetary body, then it would make engineering challenges of living in space a lot simpler and far less resource and energy intensive. I'm pretty certain that we can and maybe will at least do that much, assuming we don't go extinct first.

 

My point about not needing a sun was serious. Any human society will need an abundant source of energy. However, that might be internally generated inside the space habitat. A deuterium based fusion power plant would need water as feed-stock. If we take into account what we think we know about the Kuiper Belt, it seems likely that there is abundant mass at enormous distances from suns - possibly even in interstellar space. I could imagine a habitat moving from muddy snowball to muddy snowball way out there, mining the water and minerals, and never needing to approach any sun.

 

The reason I asked if you were kidding is because the sun, or, well, any star is capable of producing far more energy output then any fusion reactor we (or an advanced civilization) could ever make! Plus, our own Earth could be considered a giant spaceship that is made habitable by, guess what, our own sun. Our fossil fuels contain stored energy that originated from our sun. Even the material for fusion is star-stuff. Those simple fact alone would be enough that living like the way you described for very long would be completely idiotic, whether to us humans or to an alien civilization. You could never be able to maintain that for an indefinite period of time; eventually you would have to settle around a star system, for both the energy you could obtain AND for the simple fact that star systems usually contain a lot of the material necessary to maintain even a space faring one. Plus, why go through all that trouble when you could just tap into energy that comes right from a star or a black hole (or pulsar, etc), which will last for at least a few billion years. This would hold true even with a hypothetical nomadic space faring one...

[swansont]

It's mass is the same, but the gravitational pull of an object is also dependent on it's density and size. So, there would indeed be some gravitational problems that you would have to account for when engineering something like a full-blown Dyson Sphere.

 

But the change in gravity will not be noticable for things far enough outside of the solar system; the change in location of the mass is very small. If it's large enough to be a problem, then the systems were already perturbing each other, which would have been causing orbital issues.

 

And of course the sphere has no effect inside the sphere, assuming that the sphere's mass is uniformly distributed.

[SkepticLance]

To lucaspa

 

Your belief that we are not as smart as natural selection is probably right. The problem is that natural selection, when applied to humans, is exceedingly slow. A computer can run through a thousand generations in the time it takes you to blink. However, a thousand generations of humans takes 25,000 years. Thus, it is more likely that we will use genetic engineering to make whatever changes are needed.

 

I doubt that our current reluctance to modify humans will last. Human cultures change. By the time we have millions of people living off Earth, our attitude to genetically modifying people is likely to be massively different to our current superstitions.

 

Perhaps, when our computer and genetic science is sufficiently advanced, we can use computer based natural selection to model the human genome and simulate its evolution under differing environmental changes. Then we could synthesize the best genes and insert them into humans.

 

The other thing that will happen, if we are looking at human society long term, is a massive extension of human life span. Once we learn to silence all the genes that cause ageing, humans will live for hundreds, if not thousands of years. This will probably not happen for at least another 100 years, but is rather likely eventually. What are the implications for social change?

 

Lockheed does not like my idea of fusion power on board habitats. However, there are major benefits in terms of mobility - being self sufficient. It also creates independence from an external energy source that might be fought over by different competing human communities. It permits slow travel between star systems, which might take generations. And the energy availability is enormous. Small amounts of deuterium, in theory, could be enough to supply millions of people with all the energy they will need.

 

A question related to Dyson Spheres. Where does the gravity come from? or is this a situation where we expect the future generations to be adapted to, and live in zero gravity?

 

A Ringworld gets gravity from spin. A Dyson sphere?

[swansont]

AFAIK Dyson's original concept for the sphere was for energy collection only, so there was no need to consider gravity. Nobody was going to live on it. But you do have the problem of heating everything up as the sphere comes to thermal equilibrium, if the sphere contained the planet.

[Reaper]

But the change in gravity will not be noticable for things far enough outside of the solar system; the change in location of the mass is very small. If it's large enough to be a problem, then the systems were already perturbing each other, which would have been causing orbital issues.

 

I agree with that point.

 

And of course the sphere has no effect inside the sphere, assuming that the sphere's mass is uniformly distributed.

 

Ok, but that holds only if the Dyson Sphere is fully built. What if it is only half built, or a quarter built? Clearly, gravitational problems are going to arise that would have to be taken to account.

 

Not that I haven't been doing some research on the subject though, I found a link that does describe the possibility of building one and how it may be done: http://photonswarm.com/futurology/?article=11

Wiki also provides some good ones too.

 

AFAIK Dyson's original concept for the sphere was for energy collection only, so there was no need to consider gravity. Nobody was going to live on it. But you do have the problem of heating everything up as the sphere comes to thermal equilibrium, if the sphere contained the planet.

 

I think also usable building material was also an issue, since not all of the solar system's mass can actually be used to make the sphere.

 

Lockheed does not like my idea of fusion power on board habitats. However, there are major benefits in terms of mobility - being self sufficient. It also creates independence from an external energy source that might be fought over by different competing human communities. It permits slow travel between star systems, which might take generations. And the energy availability is enormous. Small amounts of deuterium, in theory, could be enough to supply millions of people with all the energy they will need.

 

You might be able to use comets or other icy bodies for fuel and energy, but you'll also need heavy metals and heavy elements too to sustain such a life style, and large quantities of that are mostly found within star systems, which would basically defeats the purpose of never having to go to one as you are proposing. While your method might be good for traveling between star systems, you cannot hold this kind of life style for an indefinite period of time, eventually you are going to have to stop at a star system before you run out of usable resources, or energy, or both for that matter.

 

To further support my point, just because we developed the capability to last for months on end out on the oceans of Earth didn't mean we no longer needed land to live off of, and the same holds for interstellar travelers; just because they can travel between stars doesn't mean they will no longer need to depend on them.

[Luminal]

Through genetic engineering, molecular computing, quantum computing, and a host of other technologies humans have not even conceived of yet, intelligence and computation will approach the maximum in a contained amount of matter (such as this planet or solar system). That maximum is far beyond the intelligence or computation of a human brain or modern supercomputer.

 

That, of course, will rapidly lead to the production of all technological capabilities in a finite amount of time, probably within 1,000 years.

 

If there is any way possible to stretch, shrink, or generally manipulate space, time, or physical constants, then intelligent life would rapidly discover the means to do so.

 

That leads me to the opinion that there is a high probability that intelligent life is exceedingly rare. And if it does exist, it intentionally is masking the signs of its civilization from developing intelligent life.

[SkepticLance]

To Lockheed

 

Re harvesting matter in interstellar space. I meant this as a possibility only. We do not actually know how much matter is between stars. There is a strong body of thought that the Kuiper Belt, which extends way out into extrasolar space, contains a number of planets, moons and trillions of cometary bodies. These may well be available for harvesting in immense numbers throughout the galaxy, including half way between stars.

 

When I was much younger, I worked as an indistrial chemist for a company that made a wide variety of products. One was a rock fibre for insulation. Basalt rock was melted in an arc furnace and blasted with air to blow it into fibres. A byproduct of the process was pig iron that was sold. I say this simply to point out that minerals can be obtained from what seems to be useless rock, even with our technology. A few thousand years from now, who knows what humans will be able to extract from cometary bodies.

 

However, it may be that there is too little matter between stars. Our descendents will find out.

[lucaspa]

To lucaspa

 

Your belief that we are not as smart as natural selection is probably right. The problem is that natural selection, when applied to humans, is exceedingly slow. A computer can run through a thousand generations in the time it takes you to blink. However, a thousand generations of humans takes 25,000 years. Thus, it is more likely that we will use genetic engineering to make whatever changes are needed.

 

The problem is that natural selection monitors thousands/tens of thousands of cost/benefit analyses. Also, we cannot predict new environments that humans will encounter. Yes, we can use genetic engineering to make changes, but that doesn't mean they will be good changes. That's why I say it is stupid. When we do genetic engineering, we are arbitrarily stating some traits are "good" and others "bad", without natural selection's ability to consider the entire organism re the environment.

 

I doubt that our current reluctance to modify humans will last. Human cultures change. By the time we have millions of people living off Earth, our attitude to genetically modifying people is likely to be massively different to our current superstitions.

 

Why? How do you calculate "likely"? And I'm not talking "superstition", remember. I'm talking reluctance as very good science.

 

Perhaps, when our computer and genetic science is sufficiently advanced, we can use computer based natural selection to model the human genome and simulate its evolution under differing environmental changes. Then we could synthesize the best genes and insert them into humans.

 

And here is the fallacy I talked about in my first paragraph of this post: the idea of "best" genes that human arbitrarily pick. "Best" for what? To say "best" means humans are inserting their judgement calls -- what you call "superstition".

 

The other thing that will happen, if we are looking at human society long term, is a massive extension of human life span. Once we learn to silence all the genes that cause ageing, humans will live for hundreds, if not thousands of years.

 

Nope. Not even close to viewing the total biological problem. You think aging is only due to some genes. Not so. There are many other problems, such as repairing methylation of DNA in somatic cells, as well as replacing cells that undergo apoptosis because of the damage and just normal wear and tear.

 

That's the problem with this thread: people are being way too simplistic in looking at the situation. It's basically a cartoon of what the problems are. Simplify them down and then wish the problems away.

 

Lockheed does not like my idea of fusion power on board habitats. However, there are major benefits in terms of mobility - being self sufficient.

 

In contrast, I like the idea of fusion power on board habitats. Yes, I think it is a technology that can be achieved. The problems I foresee are not those of fusion power, but those of having a sufficient industrial base for replacement of parts aboard a habitat in interstellar space and the major danger of collisions with interstellar matter. Not to mention the economic difficulties of getting the habitats to begin with. In order to operate the habitats, you must have effective birth control. BUT, if the society has effective birth control, there is no reason to build the habitats to begin with! There would be more than enough room on the planet! Also, where does the capital come from to build the habitats? Where is the return on investment? You would need a government. But very few governments could, in a situation of population growth you imagine, be able to divert the massive resources to build a habitat for a few thousand when millions could use the resources.

 

So you have a chicken/egg problem in getting the habitats into existence. The very conditions in which you say you need the habitats are the very conditions that ensure they can't be built.

 

Small amounts of deuterium, in theory, could be enough to supply millions of people with all the energy they will need.

 

But where does the reaction mass come from to accelerate and decelerate the habitats? A habitat large enough to have "millions of people" is enormous. A huge mass.

 

A question related to Dyson Spheres. Where does the gravity come from? or is this a situation where we expect the future generations to be adapted to, and live in zero gravity?

 

A Ringworld gets gravity from spin. A Dyson sphere?

 

Also from spin. Latitudes would have different gravities with the greatest gravity at the equator and no gravity at the poles.

 

Through genetic engineering, molecular computing, quantum computing, and a host of other technologies humans have not even conceived of yet, intelligence and computation will approach the maximum in a contained amount of matter (such as this planet or solar system). That maximum is far beyond the intelligence or computation of a human brain or modern supercomputer.

 

Since the computation ability depends on quantum computing, molecular computing, (both of which have not been shown to work) and a "host of technologies humans have not even conceived of", how are you sure your conclusion is going to happen? You are saying that imaginary processes will absolutely become reality. Don't you see the illogic in that?

 

If there is any way possible to stretch, shrink, or generally manipulate space, time, or physical constants, then intelligent life would rapidly discover the means to do so.

 

Why? Why does all intelligent life have to do this? You forget that not only is intelligence needed, but also the ability to make tools. Could dolphins discover all this? Nope. Also, you need motivation. You are assuming human levels of curiosity. Is this level of curiosity a requirement of intelligence? If so, why?

 

And if it does exist, it intentionally is masking the signs of its civilization from developing intelligent life.

 

Why would it do that? We have the curiosity to learn about other species and cultures. You are saying that an intelligent species has the same curiosity in order to develop the technologies you are talking about suddenly does NOT have the curiosity to contact other intelligent species? Sounds like inconsistency and special pleading.

[SkepticLance]

lucaspa said :

 

"When we do genetic engineering, we are arbitrarily stating some traits are "good" and others "bad", without natural selection's ability to consider the entire organism re the environment."

 

That goes without saying. However, did you not consider that the results of genetic engineering also are subject to selection - both natural and by humans? In other words, the mistakes will be eliminated (by deleting the genes that prove to be poor adaptors) from the population. Genetic engineering will accelerate what might otherwise happen with natural selection, and will introduce genes that would never otherwise exist. Sure there will be mistakes, which will need correcting. There will also be a degree of genetic innovation that natural processes could not achieve in less than hundreds of millions of years.

 

"Why? How do you calculate "likely"?"

 

Here we are talking about changes in human attitudes. When we look at recent human history, we can see how these change, and especially in response to the changes brought by technology. Not long ago, birth control was considered immoral by millions of people. Today, even amongst catholics, it is almost universally used. A few decades back, the idea of human artificial insemination was considered anathema by most people. Today, it is in such wide use, that it is almost unremarked. Numerous such examples exist.

 

Today, the idea of human cloning is considered anathema, also. In another hundred years????

 

Ditto to attitudes towards human genetic engineering. Today, no way. Tomorrow it will probably be all go. Cultures change. Attitudes change. The only sure prediction is change.

 

Genetic engineering will begin as the small, clearly obvious changes, such as preventing genetic disease. Then we will move on to small improvements - making people healthier, stronger, better eye sight etc. Later, we will introduce more powerful intelligence (when we work out what intelligence is, anyway). Further on, when we have people living in hostile environments, it will make sense to introduce genes that better adapt them to that environment. etc.

 

"You think aging is only due to some genes."

 

I have read a number of different theories of ageing. It seems probable that there are a number of causes. However, genes will be a major factor, and longevity will be achieved to some extent by gene alterations. How much is something we could debate without resolution for many posts. I doubt that the other, non gene, causes of ageing will be unamenable to treatment, when that treatment is backed by another 100+years of medical research.

 

"That's the problem with this thread: people are being way too simplistic in looking at the situation. It's basically a cartoon of what the problems are. Simplify them down and then wish the problems away."

 

This is probably correct, but so what!

We are bouncing ideas around, and looking at possible futures. The one thing that we can be sure of regarding predictions, is that most will be wrong. In the mean time, we have fun, and both our spirits and imaginations are stirred.

 

Society will develop in the way that society develops. All the complexity that is required for that future society will evolve. That situation will likely include a number of the concepts we are presently sharing, much modified to adapt to the situation. If we get only bits of it right, that is also fine.

 

"In order to operate the habitats, you must have effective birth control. BUT, if the society has effective birth control, there is no reason to build the habitats to begin with!"

 

Lucaspa, you appear to be a great believer in natural selection. Apply your brain to this. Given birth control, with women very successfully deciding how many children to have, and assuming that a part of that love of children is genetic, what will happen to the spread of the gene(s) for loving children over many generations? What will that do to population control in the long term?

 

Also, add in the strong possibility of very long life to population size. The need for new human habitats could become critical.

 

"But where does the reaction mass come from to accelerate and decelerate the habitats?"

 

It comes from the muddy snowballs that are mined for resources. Even a small comet contains more mass in the form of volatiles than any space city is likely to need as reaction mass. The other thing is that the reaction mass effect is dependent on exhaust speed. We can assume that a highly advanced technology will be able to accelerate the reaction mass to close to the speed of light (after all, we can already do that in particle accelerators). The exhaust velocity effect is logarithmic. A small amount of mass at very high velocity gives strong acceleration.

[Reaper]

You would need a government. But very few governments could, in a situation of population growth you imagine, be able to divert the massive resources to build a habitat for a few thousand when millions could use the resources....

 

The launching of Cosmos 1 (and some other notable space projects) did not require a government though. Also, as time progresses the per capita income, GDP, GNP, and the overall economy as it exists today will likely continue to rise overall; it has been ever since we've progressed up the technological and social ladder. And, maybe not in the U.S., but certainly elsewhere.

 

It is also conceivable that independent organizations, such as corporations or non-profit ones for example, will be able to gather enough resources to undergo and fund such an effort in the future independently of the governments. Indeed, organizations and corporations already earn way more than governments do, and they are now largely the ones responsible for funding many major projects ranging from space travel to feeding the hungry today.

 

===================================================

 

 

As for potential benefits associated with these habitats, I can list several. For example, tourism. Not every benefit has to be tangible you know. Also, such habitats can easily be adaptable to being able to serve as harvesters or something. They could also act as zero-g industrial plants. Or docking stations. On the contrary, they can do a great many of things; their functions need not be restricted to serve as population control you know.

 

 

I have read a number of different theories of ageing. It seems probable that there are a number of causes. However, genes will be a major factor, and longevity will be achieved to some extent by gene alterations. How much is something we could debate without resolution for many posts. I doubt that the other, non gene, causes of ageing will be unamenable to treatment, when that treatment is backed by another 100+years of medical research.

 

It's not entirely due to genes though. Even if we do find those genes responsible for some aspect of it, aging will still happen, simply because of sheer erosion of our bodies. It may not even be possible to extend our life much beyond 120 or 130 unless we make some radical changes in our cellular processes or physiologies.

 

To Lockheed

 

Re harvesting matter in interstellar space. I meant this as a possibility only. We do not actually know how much matter is between stars. There is a strong body of thought that the Kuiper Belt, which extends way out into extrasolar space, contains a number of planets, moons and trillions of cometary bodies. These may well be available for harvesting in immense numbers throughout the galaxy, including half way between stars.

 

 

When I was much younger, I worked as an indistrial chemist for a company that made a wide variety of products. One was a rock fibre for insulation. Basalt rock was melted in an arc furnace and blasted with air to blow it into fibres. A byproduct of the process was pig iron that was sold. I say this simply to point out that minerals can be obtained from what seems to be useless rock, even with our technology. A few thousand years from now, who knows what humans will be able to extract from cometary bodies.

 

But that was because the elements necessary to make such products were already there. We do have a good idea of what of elements there are in the kuipier belt or similar locations around stars, and so far there is no reason to believe that there are very many heavy elements out in the fringes. Our supernova models and star formation models don't really predict that we will find such materials in large quantities very far out from a star system simply because of how they are distributed (lighter ones get blown off first, then the heavier ones, also, heavier ones tend to concentrate together.)

 

However, it may be that there is too little matter between stars. Our descendents will find out.

 

And that is true. For all we know, we could discover just about anything out there. It's not like we haven't been surprised before since we started looking out into the stars...