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Matt Giwer
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Message 960671 - Posted: 3 Jan 2010, 19:26:27 UTC

There are other lead-ins to dump cold water on the idea of interstellar visitors. Let me extrapolate using solely technologies we are reasonably certain can develop into advanced technologies but without magic, miracles or at any time my hands leaving my wrists.

The big bugaboo of interstellar travel is, "within our or a reasonable lifetime." That appears to preclude meeting up with ET and killing him, her or it.

It is reasonably certain space tourism is coming as the spaceport in Arizona is under construction and the commercial spaceship is nearing completion. So it is not much of a step to expect in this century a tourist hotel in orbit. It is also within reason to assume eventually a 2001-type which rotates for something as biologically as good as gravity will be built. A hotel for the rich will require employees to provide for their needs. In other words, space will be for the Bill Gateses and the bartenders of the world.

The energetics of getting to and from orbit are not going to become less than two weeks pay for a bartender absent magic which I have promised not to invoke. Therefore employees will get a modest deal to take their vacation in orbit in return for a bonus based upon the cost difference. People start to stay in space.

Now we have found water on the moon. The energetics of water from the moon to earth orbit than from earth to orbit therefore a moon industry for water (also hydrogen and oxygen) can compete with earth. People have real jobs in space. Similarly increasing the size of the hotel, building a competing hotel and Chez Gates in orbit gets cheaper raw materials from the moon than from earth. It does not stop there.

Roughly from LEO one is half way to anywhere based upon energetics. Once refining and fabrication methods in space are developed raw materials come from comets and asteroids rather from the earth. For power in earth orbit there is roughly 2kW per sq meter. For more concentrated energy and which is available in any orbit fusion is on the horizon -- as it has always been I admit.

This is where the bugaboo of the huge travel times works to advantage. Fusion can be on the horizon for the next thousand years or even ten thousand and nothing material changes in our travels to the stars.

But who would give up a good life and hibernate or sign on to a generation ship just to visit Alpha Centauri? Yes there is always someone but there is no need to invoke such an idea.

Once there are industries in space people will live there full time. Dig up the Cities in Flight series of Blish. There is our space civilization merely taking to living in space with an occasional exotic vacation to Mars, Luna or even Earth for the antiquarians at heart.

The next strange things these cities do is have people who are fruitful and multiply. Thus the cities multiply and near sun resources are used up and the cities migrate farther out. I leave the collection of census data for the Oort Cloud to people ten thousand years from now. There is no hurry.

Once there is a well populated Oort cloud travel to Centauri is not a great challenge but something schoolchildren why no one has done it. 10kyr in our future is nearly twice as great as to the first cities of our past.

I promised no magic so how did they get that far from the sun? Mass drivers powered by fusion of course. And as they move outward in the direction of planetary rotation they mass losses velocity and falls inward. With a decent legal system the collected mass in the inner system is sold. Given this economy information is the only commodity that can be traded but that is what Hollywood and patent offices are for.

Notice nothing more than existing and prospective technologies which may take thousands of years to perfect but no magic and no miraculous new technology and no exceeding the speed of light.

But we still have not populated the universe. So a mere thousand years to get to Centauri for a total of 11kyr in our future. Lets say it turns out to be a treasure trove of raw materials with trivial gravity wells and it takes another 10kyr before they think it time to move on. And lets say they are incredibly conservative and only travel to two different stars to start again. 11kyr in their future and 22kyr in ours they split ago and head for two stars each for four total plus the original Earth, Centauri and its first two. Now there are seven stars with human civilization.

In a MERE eleven million years there are 2^1000 stars with human civilization. Say this is wildly optimistic and each step takes ten times longer. Then it is still a MERE 110 million years.

As Fermi asked, where are they?

If you totally despise my hotels in space scenario substitute any long term reason to be in space and consider the energetics of supplying people in space are all in favor of raw materials from space rather than from Earth. Everything that suggests going into space indicates greater reasons to stay there because of the Earth's gravity well. So instead of this century's hotels in orbit if it takes 10,000 years for the cycle to start it takes 110,000,000 plus 10,000 years before there is a human civilization in 2^1000 star systems.

Fermi asked a good question. 110,010,000 million years is roughly 2.5% of the age of our sun which is 3% the age of the universe. Where are they?

Not a single argument based upon distance/travel time holds water. I arbitrarily suggest each step takes ten times longer and nothing changes. It has to be 100 times longer to begin to make a difference.

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Message 960680 - Posted: 3 Jan 2010, 19:35:02 UTC

Fusion power is only a costly dream. The ITER concept demonstration plant is already beyond schedule and has overcome its budget by a factor of two. Let us keep our feet on this Earth and maybe have more care of it.
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Message 960947 - Posted: 5 Jan 2010, 18:27:44 UTC - in response to Message 960680.

Fusion power is only a costly dream. The ITER concept demonstration plant is already beyond schedule and has overcome its budget by a factor of two. Let us keep our feet on this Earth and maybe have more care of it.
Tullio

I agree completely. It may take ten thousand years to make it practical. That does not make a significant difference on the spread of human civilization among the stars.

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Message 961010 - Posted: 5 Jan 2010, 22:03:41 UTC - in response to Message 960947.

and what if an alien civilization was around 1 million years ago but faded out. We can only hope that there is something out there that is currently intelligent to send and receive radio waves
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Message 961075 - Posted: 6 Jan 2010, 2:27:37 UTC - in response to Message 961010.

and what if an alien civilization was around 1 million years ago but faded out. We can only hope that there is something out there that is currently intelligent to send and receive radio waves


In the arbitrarily ten times longer scenario human civilization will have spread among the stars in about the same time as the 100,000 years we have been around so far even though likely an additional 50,000 years earlier than that. While we may talk casually about species going extinct it happens on time scales of millions to tens of millions of years.

We have more than enough time to expand to the stars before an extinction time event occurs. The shortest reasonable time to expand to the stars is a million years to maybe ten thousand stars. With such diversification no single extinction event can occur.
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Message 962452 - Posted: 10 Jan 2010, 5:33:28 UTC
Last modified: 10 Jan 2010, 5:36:19 UTC

I think interstellar distances would not be such a problem if we did, or they do, live for thousands of years. Couldn't there be life forms that live longer, maybe much longer than we do?

Martin

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Message 962538 - Posted: 10 Jan 2010, 19:19:10 UTC - in response to Message 962452.

I think interstellar distances would not be such a problem if we did, or they do, live for thousands of years. Couldn't there be life forms that live longer, maybe much longer than we do?

Martin


Note I did start with a premise that I would only assume the perfection of existing technologies on our part. Thus no magic and such longevity would constitute magic.

The fallacy in worrying about travel times is assuming homeworld to homeworld travel. However all that matters in meeting ET is the lifetime of a species. We do have a handle on how long species survive. The only problem here is defining what is meant by species.

For example if we use only our present working definition then our species has been around for between 100 and 150 thousand years. That is about 10% of the average life of a species although the fossil record is so sparse it is not wise to make definite statements in this matter.

If we take the start of our species as Lucy we are talking about 3 million years for us. It is thus reasonable to suggest our evolutionary descendants will eventually look back on us as 3 million years in their past. They can also expect their descendants to have a similar 3 million year look back.

I do expect a major survival of sentient species in that it has shown itself to be incredibly successful by the measures of species success. We have populated just about the entire world with its huge variation in climate and ecologies. Changing climate is what appears to get most species. The other species killer is competition from a new predator. The most dangerous species ever to walk the earth is a killer ape. Just to show how mean they are, half of them are female. Meaning it is not clear how a competing species can arise that is not an offshoot of us.

So in the worst case of just us as a narrowly defined species we should have populated the space around dozens of stars. It is unclear what single event could end our species and all possible descendant species.

It is reasonable to assume once we populate stars the fact that their only contact is electromagnetic rather than physical speciation should occur. Give each of those species a reasonable life expectancy and we populate the galaxy in a few millions or tens of millions or even few hundreds of millions of year.

The same things applies to ET regardless of his individual lifespan.

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Message 962571 - Posted: 10 Jan 2010, 21:43:39 UTC - in response to Message 962538.
Last modified: 10 Jan 2010, 21:55:14 UTC

Ok then, I withdraw the question.

Martin
[edited]...

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Message 962621 - Posted: 11 Jan 2010, 2:30:10 UTC - in response to Message 962538.
Last modified: 11 Jan 2010, 2:34:28 UTC

No offense intended, but I think your premise (and indeed, Fermi's as well) is inherently weak, naive, and short-sighted. Your mistake is in assuming that the current human biological and social paradigms will persist without fundamental alteration indefinitely into the future.

You base your line of reasoning on the flimsy premise that within the next tens of thousands, even millions of years humans will either not be significantly physiologically and mentally altered by technology or that their "descendants" will be solely the products of natural Darwinian evolution.

It's extremely naive not to consider the future prospects of expanded genetic manipulation, biological and technological enhancement, and the increasing potential of AI.

Not only that, but you impose the relatively modern (and historically brief) socio-political pattern of exponential population growth, expansion, and colonialism universally on hypothetical human societies which will be millions of years more advanced than our own (whose societies, cultures, and motives are likely as impossible to fathom as ours would be to "Lucy"). Obviously, this pattern hasn't even applied universally to all human societies on Earth throughout history, it seems a bit narrow-minded to apply it to humanity indefinitely into the future.

Humans will colonize Alpha Centauri? Really? Why?
Can you give specific, concrete material reasons beyond vague allusions? The stabilization of Earth's population and technologies like nuclear fusion (as you mention) make it impossible to imagine that demand for resources will be a motivating factor.

And specifically what makes colonization of distant extrasolar planets at considerable cost and effort (regardless of technology) the preferable or inevitable alternative to preserving and studying them?

I did start with a premise that I would only assume the perfection of existing technologies on our part. Thus no magic and such longevity would constitute magic.


No offense but you're wrong on this one too.

Indefinite lifespan extension, even lifespans numbering in the thousands of years, isn't "magic". Not only do a growing number of scientists believe that lifespan extension of thousands of years or more is inevitable, a good deal believe that such lifespan extension will be possible for some individuals alive today.

Since the basic mechanisms behind the aging process are fairly well understood (even though the complex interplay of causes isn't), solutions can be engineered to delay, halt, or even reverse those processes. Indeed, the number of published papers on successes in this field is growing by leaps and bounds every year and induced delayed aging in the lab is nothing more than a mundane reality.

Calorie Restriction, Methionine Restriction, IGF1 manipulation, SIRT1 activation, Autophagy, all of these processes significantly extend lifespan; millions of dollars are being invested to transfer these to pharmacological interventions (for those not willing to adhere to strict lifestyles, like CR for example). Targeted manipulation of Mitochrondrial DNA, cellular proteins, and amyloid plaques is becoming more and more feasible due to the prospects of precision enzyme and nanotechnology which could be administered to aged persons via rejuvenation therapies or used to immunize against further aging.

The bottom line is that indefinite lifespan extension is not magic and it would be naive NOT to presume that any technological civilization whose age differs from ours on a scale of millions or billions of years doesn't possess technology which we ourselves will possess within a span of decades.

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Message 962823 - Posted: 12 Jan 2010, 1:02:42 UTC - in response to Message 962621.

No offense intended, but I think your premise (and indeed, Fermi's as well) is inherently weak, naive, and short-sighted. Your mistake is in assuming that the current human biological and social paradigms will persist without fundamental alteration indefinitely into the future.


I try to be wrong every decade or so just so I won't forget what it is like. I cannot be offended.

You base your line of reasoning on the flimsy premise that within the next tens of thousands, even millions of years humans will either not be significantly physiologically and mentally altered by technology or that their "descendants" will be solely the products of natural Darwinian evolution.

It's extremely naive not to consider the future prospects of expanded genetic manipulation, biological and technological enhancement, and the increasing potential of AI.


Lets not get ahead of me. I did not propose to say it will happen as I described initially. I propose that it can happen given only the technologies we have but perfected -- fusion being nearly a cure all I let in with this. Whether or not we do it or do not do it because of some other change is moot. Some fraction of species will do it as whatever might stop us cannot be assumed to be universal. But even with something that stops us it is hardly reasonable to consider whatever it is will be permanent. So we alter ourselves. Nothing suggests it would be impossible to change back or another change which again makes this possible.

Not only that, but you impose the relatively modern (and historically brief) socio-political pattern of exponential population growth, expansion, and colonialism universally on hypothetical human societies which will be millions of years more advanced than our own (whose societies, cultures, and motives are likely as impossible to fathom as ours would be to "Lucy"). Obviously, this pattern hasn't even applied universally to all human societies on Earth throughout history, it seems a bit narrow-minded to apply it to humanity indefinitely into the future.

Humans will colonize Alpha Centauri? Really? Why?


I can hardly be accused of applying the last few centuries of colonialism when the colonies were founded in places already populated. That Columbus found the land populated hardly suggests colonialism is a new idea. Rather colonialism is a just a name given to the way Europeans did it. The Siberians of 17,000 years ago may or may not have had their own name for it.

As for Centauri, I propose the Siberian method. People having lived in space for thousands of years using up inner system resources expanding outward to the Oort cloud and ultimately better pickings in a virgin solar system. (I expect interstellar space to be filled with Oort-like bodies but that is not necessary.) The main cause for this would be the objects with the heavier elements being used up.

The thing that would certainly slow this down would tread on this is perfecting fusion to the point of creating all the elements as needed. But eventually everything gets used up. Not the Jovian planets as the premise here is the energetics of obtaining resources from space is always less than getting them from a planet.

Can you give specific, concrete material reasons beyond vague allusions? The stabilization of Earth's population and technologies like nuclear fusion (as you mention) make it impossible to imagine that demand for resources will be a motivating factor.

And specifically what makes colonization of distant extrasolar planets at considerable cost and effort (regardless of technology) the preferable or inevitable alternative to preserving and studying them?


As the model is existing cities going to them as Siberian tribes migrated eastward rather than the European model cost is not a driver. Once in the Oort cloud what is the difference between staying there and moving on to another star? I admit to a bit of handwaving here.

To my own mind I am glossing over the fact that for some reason the industrial revolution got us out of the malthusian trap of increasing population to eat up the gains of advancing technology even if it was only the horse collar. Therefore an expanding population needing more and more cities and thus resources is not a given. But in the long run this appears to only slow things down where the need for extrasolar resources is directly dependent on the recycling efficiency of even a stable population. Note nothing really changes if things take 100 times longer. Nothing really changes until it takes longer than third generation stars have been around.

I did start with a premise that I would only assume the perfection of existing technologies on our part. Thus no magic and such longevity would constitute magic.


No offense but you're wrong on this one too.

Indefinite lifespan extension, even lifespans numbering in the thousands of years, isn't "magic". Not only do a growing number of scientists believe that lifespan extension of thousands of years or more is inevitable, a good deal believe that such lifespan extension will be possible for some individuals alive today.


While many may believe this I have seen no progress in identifying what to do that can do more than let everyone live to around 95 +/- 10 years. We seem to be doing nothing more than helping people live longer to die of another disease -- quit smoking so you can die of Alzheimer's. Therefore lifespans beyond this do not fall into the category of the perfection of an existing technology.

Since the basic mechanisms behind the aging process are fairly well understood (even though the complex interplay of causes isn't), solutions can be engineered to delay, halt, or even reverse those processes. Indeed, the number of published papers on successes in this field is growing by leaps and bounds every year and induced delayed aging in the lab is nothing more than a mundane reality.

Calorie Restriction, Methionine Restriction, IGF1 manipulation, SIRT1 activation, Autophagy, all of these processes significantly extend lifespan; millions of dollars are being invested to transfer these to pharmacological interventions (for those not willing to adhere to strict lifestyles, like CR for example). Targeted manipulation of Mitochrondrial DNA, cellular proteins, and amyloid plaques is becoming more and more feasible due to the prospects of precision enzyme and nanotechnology which could be administered to aged persons via rejuvenation therapies or used to immunize against further aging.


With so many possibilities there may someday be accepted therapies to greatly extend life. If one assumes they are all going to some day pay off I still do not see much impact on this question.

The bottom line is that indefinite lifespan extension is not magic and it would be naive NOT to presume that any technological civilization whose age differs from ours on a scale of millions or billions of years doesn't possess technology which we ourselves will possess within a span of decades.


The usual context of the subject of this thread is how long it would take. The problem with making it practical is finding volunteers. The number of volunteers can be seen as increasing with the smaller the fraction of one's life being involved when it comes to travelling for the sake of travelling. The Brits did get people to undertake up to two year trips of exploration but with the expectation of many landfalls along that way not a year between landfalls. This would be no more than 1/30th of a lifetime at that time.

At 0.1c Alpha Centauri is a 90 year round trip equivalent to a 2700 year life span. No lab research even hints at such a thing. Therefore magic.



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Message 966183 - Posted: 27 Jan 2010, 18:24:19 UTC - in response to Message 962823.
Last modified: 27 Jan 2010, 18:35:14 UTC

Lets not get ahead of me. I did not propose to say it will happen as I described initially. I propose that it can happen given only the technologies we have but perfected -- fusion being nearly a cure all I let in with this.


To be fair, the fusion you describe (i.e. used to power interstellar travel) is less rooted in hard science than the extended lifespans I describe...

Whether or not we do it or do not do it because of some other change is moot.


Far from being moot, it is indeed THE central point (that you're missing). If some fundamental change associated with the technologies you describe makes the future you describe a non-starter, I'd say that's quite relevant to the topic at hand.

Some fraction of species will do it as whatever might stop us cannot be assumed to be universal.


If your assumption that technological civilizations will at least develop the capacity to leave their solar systems is universal enough that no matter how rare such civilizations are some others must have already undertaken such journeys, then I think it's fair to say there are inherent, inextricable aspects of technology from which no civilization that develops the capacity to leave its solar system can ever untwine. Given what we already know, it seems likely that these specific aspects of technological evolution will preclude the scenario you outlined from ever happening since it's based on the assumption of human-like technology in the first place.

But even with something that stops us it is hardly reasonable to consider whatever it is will be permanent.


Quite the opposite; it's much more reasonable to make the basic assumption that some technologies are fundamentally and permanently linked to other technologies than to assume that socio-cultural behaviors are permanent (especially for thousands, tens of thousands, or hilariously enough, millions of years).

So we alter ourselves. Nothing suggests it would be impossible to change back or another change which again makes this possible.


Seeing as you're incapable of transforming yourself into an Australopithecine primate or a bacterial colony, or your desktop computer is not able to spontaneously turn into an Abacus, plenty suggests it's impossible to "change back".

People having lived in space for thousands of years using up inner system resources expanding outward to the Oort cloud and ultimately better pickings in a virgin solar system.


Over what span of time would the "inner system resources" be used up? And specifically what resources are you referring to? Silicate rock? Heavy elements like iron? Aren't you missing something really big and really shiny at the center of the our solar system?

The thing that would certainly slow this down would tread on this is perfecting fusion to the point of creating all the elements as needed.


Whoa, wait a sec....
Fusion is an "existing technology perfected" (fair enough), but it we won't be capable of utilizing it to produce heavier elements as needed until the resources of the inner solar system get used up? So I'm guessing that fusion technology will be more or less stagnant for the thousands of years that pass until that happens, right?

But eventually everything gets used up. Not the Jovian planets as the premise here is the energetics of obtaining resources from space is always less than getting them from a planet.


I'm still not clear on what we're using these resources for in the first place? Am I correct in guessing that you're predicting unbounded Malthusian population growth?

As the model is existing cities going to them as Siberian tribes migrated eastward rather than the European model cost is not a driver. Once in the Oort cloud what is the difference between staying there and moving on to another star? I admit to a bit of handwaving here.


So the answer is no, you don't have anything concrete on which you base your assumptions...

To my own mind I am glossing over the fact that for some reason the industrial revolution got us out of the malthusian trap of increasing population to eat up the gains of advancing technology even if it was only the horse collar. Therefore an expanding population needing more and more cities and thus resources is not a given.


"For some reason"? You could google this stuff, you know. With the internet and the vast wealth of papers written on this subject at your finger tips there really isn't an excuse not to know if it's central to some topic you seem to have invested some thought into.

But in the long run this appears to only slow things down...


Source?

...where the need for extrasolar resources is directly dependent on the recycling efficiency of even a stable population.


And on what do you base your assumptions regarding the "recycling efficiency" of future societies?

Note nothing really changes if things take 100 times longer.


Of course, nothing changes at all.....except our level of technology, our potential ability to manipulate the physical universe, and we ourselves. You're right, that all amounts to "nothing" really.

While many may believe this I have seen no progress in identifying what to do that can do more than let everyone live to around 95 +/- 10 years. We seem to be doing nothing more than helping people live longer to die of another disease -- quit smoking so you can die of Alzheimer's. Therefore lifespans beyond this do not fall into the category of the perfection of an existing technology.


Some sweeping, factually baseless generalizations there. Like I said, you could do some basic research into this issue if you're interested.

The usual context of the subject of this thread is how long it would take.


And that was your first mistake; focusing on a strawman. I'm not aware of any astronomer, physicist, or SETI proponent who claims that ET wouldn't travel interstellar distances *solely* due to the amount of time it would take.

There are much more obvious and fundamental considerations regarding interstellar travel (i.e. "why bother in the first place?"); afaik nobody claims that ET wouldn't have the time...and unlike you, none of them are bold enough to make the mundane assertion that lifespan will be an issue either.

The problem with making it practical is finding volunteers.


Says you. That's another strawman.

....equivalent to a 2700 year life span. No lab research even hints at such a thing. Therefore magic.


So I guess Sequoia trees are employing magic to routinely reach lifespans over 2,000 years?
Aubrey de Grey's "longevity escape velocity" might appear far-fetched but only if one glances at it superficially; those who dismiss him out-of-hand do so at the risk of looking extremely foolish...
http://en.wikipedia.org/wiki/De_Grey_Technology_Review_debate

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Message 967237 - Posted: 31 Jan 2010, 5:47:51 UTC - in response to Message 966183.

Lets not get ahead of me. I did not propose to say it will happen as I described initially. I propose that it can happen given only the technologies we have but perfected -- fusion being nearly a cure all I let in with this.


To be fair, the fusion you describe (i.e. used to power interstellar travel) is less rooted in hard science than the extended lifespans I describe...


Perhaps you are more familiar with the medical sciences than I. I do not see it. In life extension I see none. I do see major advances in eliminating the causes of early death but none in extending life.

As for fusion the first breakeven point has been achieved and in only 55 years from first attempt. If it takes 10,000 more years to use it for propulsion nothing really changes in the scenario I describe. Basically the rule was to show it could be done without needing to discover warp drive or some such.

But if all you want is effective immortality, life spans longer than meat time between fatal accidents, I won't argue against it. I said as one of my groundrules I would not invoke anything not known today. By that groundrule I would see everyone living to about 130 based upon today's knowledge.

Whether or not we do it or do not do it because of some other change is moot.


Far from being moot, it is indeed THE central point (that you're missing). If some fundamental change associated with the technologies you describe makes the future you describe a non-starter, I'd say that's quite relevant to the topic at hand.


The future I start with is space tourism. That starts late this year or early next from a spaceport in New Mexico. When does this change you propose set in and what might it be to cease to make space an attraction for rich tourists? What can change that will not make it cheaper as time goes one? The rest is based upon the simple fact that deep space to earth orbit requires less delta-v than from the surface to orbit.

Some fraction of species will do it as whatever might stop us cannot be assumed to be universal.


If your assumption that technological civilizations will at least develop the capacity to leave their solar systems is universal enough that no matter how rare such civilizations are some others must have already undertaken such journeys, then I think it's fair to say there are inherent, inextricable aspects of technology from which no civilization that develops the capacity to leave its solar system can ever untwine. Given what we already know, it seems likely that these specific aspects of technological evolution will preclude the scenario you outlined from ever happening since it's based on the assumption of human-like technology in the first place.


You appear to be saying, the have not dropped in for a beer so they never left home. If you take a look at the number of UFO sightings being reported each week then if 1/10 of 1% of them are "visitors" then we are a very popular destination. It is just the way things are that all can not be explained and the unexplainable fraction will in fact remain a very large absolute number. So there is no reasonable way we can say there are not many civilizations out there right now and many in fact visiting us.

As for actual visits many people have reported such visits. And of course their stories mostly sound real stupid peace and platitudes. The Aztecs met of lot of Padres mouthing peace and platitudes. No one ever said aliens are any brighter than we are. No one ever said aliens do not have their scientologists.

And then there is my favorite teenagers getting drunk and using the family flying saucer to terrorize the natives. The real scenario of contact it guaranteed not to have the dramatic impact of a Hollywood movie and no orchestral theme music. The landing in 1492 was a middle aged guy getting his shoes wet and wondering to himself where the hell he was.

But even with something that stops us it is hardly reasonable to consider whatever it is will be permanent.


Quite the opposite; it's much more reasonable to make the basic assumption that some technologies are fundamentally and permanently linked to other technologies than to assume that socio-cultural behaviors are permanent (especially for thousands, tens of thousands, or hilariously enough, millions of years).


It is difficult to see how you can on one hand assert there will be an undefined change in the future that will prevent expansion and at the same time say there are no changes over tens of thousands of years. If you see yourself as being consistent in this could you explain further?

So we alter ourselves. Nothing suggests it would be impossible to change back or another change which again makes this possible.


Seeing as you're incapable of transforming yourself into an Australopithecine primate or a bacterial colony, or your desktop computer is not able to spontaneously turn into an Abacus, plenty suggests it's impossible to "change back".


Tell you what. I will take time to address this after the define the inevitable change that happens to every species which prevents travelling to to neighboring star systems.

People having lived in space for thousands of years using up inner system resources expanding outward to the Oort cloud and ultimately better pickings in a virgin solar system.


Over what span of time would the "inner system resources" be used up? And specifically what resources are you referring to? Silicate rock? Heavy elements like iron? Aren't you missing something really big and really shiny at the center of the our solar system?


I do not expect it within reason to use the suns corona as construction materials. Even if possible the energetics make it impractical. Inner system resources are the asteroid belt objects and short period comets. Using up means using in construction and operation minus the loss fraction of recycling efficiency. Eventually resources become so diffuse that the energy to collect them makes going further out for denser material more efficient.

How long depends on a lot of things. The recycling cannot be 100% means eventually concentrations of mass are used up. Eventually can be a very long time. Obviously a major factor is the reproduction rate which with modern technology can easily double the population every 40 years.

The thing that would certainly slow this down would tread on this is perfecting fusion to the point of creating all the elements as needed.


Whoa, wait a sec....
Fusion is an "existing technology perfected" (fair enough), but it we won't be capable of utilizing it to produce heavier elements as needed until the resources of the inner solar system get used up? So I'm guessing that fusion technology will be more or less stagnant for the thousands of years that pass until that happens, right?


I simply made that observation to show magic is not required in the beginning. It can happen in a hundred, a thousand, ten thousand or even a hundred thousand years but it will happen.

Consider a parallel with Columbus speculating in his declining years on perfecting sailing ships. He could have the world linked with fast trading ships using wind alone with "perfected" hull and sail design and not have to introduce a magic other means like steam. One could have done the same with steam power and speculate on coal and oil powering boilers without ever invoking diesel, turbine or nuclear engines. There is no inherent limit to any level of technology within general principles.

We do not need fusion to live and move around in space. Solar cells will do fine. They are simply inherently hugely less efficient. The ISS runs on solar power. It is not going to leave orbit. But if the ion drive being sent up in a few months works out it will be able to raise its own orbit rather than relying upon fuel from earth. Just give ion engines 100 years of progress and something that size can leave orbit. Another century should certainly get solar cells to their theoretical max efficiency and better longevity so that will go to around 35% efficiency powering 10-20% efficient ion drives. Then if solar sails work out they change the whole game.

So I simply just to fusion rather than get bogged down in the details of so many almost certain steps that will work even if we don't get to fusion until after the inner system resources are all cities. And this is not even considering the real flintstone technologies like creating a huge sphere, aluminizing the inside, cutting it in half and using it as a solar furnace for smelting iron asteroids.

But eventually everything gets used up. Not the Jovian planets as the premise here is the energetics of obtaining resources from space is always less than getting them from a planet.


I'm still not clear on what we're using these resources for in the first place? Am I correct in guessing that you're predicting unbounded Malthusian population growth?


I am very much hoping against and not planning for real Malthusian growth. I have started with simply having a reason for people being in space and then the energetics work to keep them there. For example say there is a resort or two in space for the rich. If water is found on the moon for further exploration it is also cheaper to bring water from the moon to earth orbit than from earth to orbit.

Once there are such resorts expansion requires materials which, if they can be found and fabricated beyond the earth are cheaper than bringing them up from the earth. Servicing comm sats in geosync is another obvious use. If circuits can be fabricated in space then building comm sats there of unlimited size and number becomes practical. Saving a few hundred million per launch is obvious. Not having to design to survive launch forces is another savings. Not having to design a one time repeater to fit into an available launch vehicle? Priceless!

As the model is existing cities going to them as Siberian tribes migrated eastward rather than the European model cost is not a driver. Once in the Oort cloud what is the difference between staying there and moving on to another star? I admit to a bit of handwaving here.


So the answer is no, you don't have anything concrete on which you base your assumptions...


If I remember correctly you were asking why the cost European style colonization would be undertaken. I replied the proper model is not the European style of recent memory but the Siberian model of 17,000 years ago. When a species migrates those on the leading edge of the expansion by definition have a greater resource density ahead of them than behind them.

In this scenario the resources are nothing more than mass concentrations. Eventually there will be more of them nearby then closer to home. Recycling efficiency has to be less than one. It will happen even with a fixed population.

To my own mind I am glossing over the fact that for some reason the industrial revolution got us out of the malthusian trap of increasing population to eat up the gains of advancing technology even if it was only the horse collar. Therefore an expanding population needing more and more cities and thus resources is not a given.


"For some reason"? You could google this stuff, you know. With the internet and the vast wealth of papers written on this subject at your finger tips there really isn't an excuse not to know if it's central to some topic you seem to have invested some thought into.


I said 'for some reason' because I have in fact researched the matter. The subject could serve as for all time as the ultimate resource for post hoc ergo propter hoc, circular reasoning, and non sequiturs. I am sure I missed a few categories of fallacious reasoning.

But in the long run this appears to only slow things down...


Source?


I don't have one off hand but about 20 years ago the 2050 world pop max was to be on the order of 60 billion. At the moment the max is down to about 18B and falling with each new projection. As to the "reason" for this the same thing is projected for every country even though they have all had different ways to get there. Therefore "for some reason" it is happening. It is going to happen in both "one child" China and "procreate your heart out" India on about the same schedule to the same result. It is going to happen where there is abortion on demand and where birth control of any kind is a felony.

If you think you really can explain it, publish and collect a Nobel prize.

...where the need for extrasolar resources is directly dependent on the recycling efficiency of even a stable population.


And on what do you base your assumptions regarding the "recycling efficiency" of future societies?


My assumption is that it is less than unity and therefore the only question is how long resources last. Primates in our heritage tend to last 2-3 million years and we have been around 150,000 years max. It is difficult to image an affordable efficiency that will survive the next 2 million years which has a lesser cost in energy than seeing what Alpha Centauri has to offer. But if it does then the species that replaces us has another 2-3 million years to find it cheaper to move on to another star.

Note nothing really changes if things take 100 times longer.


Of course, nothing changes at all.....except our level of technology, our potential ability to manipulate the physical universe, and we ourselves. You're right, that all amounts to "nothing" really.


I intended to say my original assumption of perfecting only existing technologies does not change the final result even if it takes 100 times longer than appears reasonable to perfect those technologies.

Remember I am looking at astronomical distances and positing "astronomic" species survival time frames against those distances. You can also look at it as I am stealing the old idea of a generation ship to get to the stars but using a Blish Cities in Flight scenario without the Spindizzy drive. I am not writing fiction so I do not have to be either dramatic or interesting.

While many may believe this I have seen no progress in identifying what to do that can do more than let everyone live to around 95 +/- 10 years. We seem to be doing nothing more than helping people live longer to die of another disease -- quit smoking so you can die of Alzheimer's. Therefore lifespans beyond this do not fall into the category of the perfection of an existing technology.


Some sweeping, factually baseless generalizations there. Like I said, you could do some basic research into this issue if you're interested.


I have. You appear to be saying you have found what I have not. URLs will be greatly appreciated. Please give a few or at least search terms that will work, the same search terms you used will be fine.

The usual context of the subject of this thread is how long it would take.


And that was your first mistake; focusing on a strawman. I'm not aware of any astronomer, physicist, or SETI proponent who claims that ET wouldn't travel interstellar distances *solely* due to the amount of time it would take.


Frankly I am unaware of any academic credential qualifying anyone in this area of speculation. But I be a physicist by sheepskin and now you are aware of a physicist who does. Does that make you more comfortable? There are no credentials in this subject. It is in fact little different from angels and pinhead speculation. The first contact is going to be a head-slapper.

There are much more obvious and fundamental considerations regarding interstellar travel (i.e. "why bother in the first place?"); afaik nobody claims that ET wouldn't have the time...and unlike you, none of them are bold enough to make the mundane assertion that lifespan will be an issue either.


I have merely said the spread across the stars will mimic the spread of Siberians to the Americas some 17,000 years ago. It would also mimic the travels of the Abos to OZ 60,000 years ago. You can also say it mimics the spread from Africa to Omam 75,000 years ago if I remember the arkie find correctly.

The problem with making it practical is finding volunteers.


Says you. That's another strawman.


I could point to the need to impress sailors, aka shanghai, but that would be cheating. You can also look to more mundane matters. There has never been an army which has had a 20 year enlistment period. Six years has been about the max and only in return for very desirable quids for the quos. You are free to find longer examples and present them. I know of none.

....equivalent to a 2700 year life span. No lab research even hints at such a thing. Therefore magic.


So I guess Sequoia trees are employing magic to routinely reach lifespans over 2,000 years?
Aubrey de Grey's "longevity escape velocity" might appear far-fetched but only if one glances at it superficially; those who dismiss him out-of-hand do so at the risk of looking extremely foolish...
http://en.wikipedia.org/wiki/De_Grey_Technology_Review_debate


It is correct that humans are not any kind of plant much less sequoias. The oldest and largest individual living creatures of fungii. I do not think you want to go there.

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