So why is it inevitable that any civilization that can evolve to the point of space travel will necessarily have the desire and capability to continue to expand before extinction? We've only been around a relatively short time and there is no certainty that we will be around long enough to be able to spread across the galaxy. If someone had told me in 1969 that 45 years later we would have lost the capability (or desire) to colonize the moon, I would have thought it highly unlikely. But here we are.
I'm not sure what "we" have lost the desire to colonize the moon, it's just that the costs far outweigh the benefits. One of the points of his article is that it will eventually be possible to build self-replicating robots that will themselves colonize the galaxy. In fact, it will become trivial to do so -- yet there are none that we've observed from other civilizations.
maybe I'm missing it, but I don't see any significant outlays of funds for colonizing the moon yet. Lots of plans an good intentions, but no will yet. And yes, it may be possible to cheaply build self-replicating robots that colonize the galaxy. But that, too, is just a speculative prediction. We're not there yet. And just as governments decided it would be better to spend their wealth on terrestrial matters rather than the moon, it remains to be seen how long it will take to make those self-replicating colonizing robots in large enough numbers to make a dent in the galaxy.
Our history is filled with explorers and frontiersmen. We've grown to fill the world. We climb mountains and explore valleys. We cross oceans and fly around the world as soon as we know how.
The resources required to traverse interstellar distances are astronomically greater than terrestrial travel (pun intended). Most species die out. How long do you believe it will take to have human explorers on the nearest extrasolar planet. And that's the easiest, closest one. Then think about how many species go extinct on this planet. There's no certainty that we will survive long enough to explore that far.
Both halves of this statement are true: our capabilities and our appreciation of the difficulties have increased, and the Apollo missions were cold-war stunts---we never had the capability to colonize the moon.
The sad part is that we don't seem to have the interest either.
It might easily have gone the other way. The Orion project lost out largely due to politics. If we had built those, we'd probably have an industrial infrastructure in space by now.
So, assume only one of ten civilizations take the expanding choice early. That is still not enough to explain the Fermi paradox.
Unrelated rant/argument:
As a civilization we should publicise "anti heroes" as much as heroes. Those who e.g. destroy something beautiful for short sighted political votes.
Not just the politicians which destroyed our space future. Another example is the present political leaders in Iraq which seems to have caused a war just because they wanted to steal more without interruptions. Would they have done that if they knew their children and grand children would be in the news when their private jets land somewhere? ("Blood billionaires land in XXX, all better restaurants take a holiday. Sorry honest rich people".)
Edit: About the Fermi paradox -- the simplest answer ought to be that there are ET probes somewhere in the solar system and probably with lots of sensors floating around. The scary part is that they don't talk to us; that implies they are studying us and will clean the local infestation out before it spreads from the solar system.
Edit 2: The full argument (I didn't see it in the article?) is that there almost certainly will be lots of civilizations in the galaxy. We have no idea if we are among the first ten or among the second thousand. So statistics say we should probably be in the middle -- there are lots before we existed, we just can't detect them.
Evolution doesn't ensure advancement in the sense of greater capabilities or greater longevity or long-term survival either. Most species on this planet have gone extinct. What's to say that species capable of altering their world don't have a higher risk of catastrophic failure. The time scales are large and there's no evidence to make a strong assertion that we as a species will be around long enough so that we can colonize galaxies. There is an assumption that advanced civilizations will last for long periods of time. It's not clear to me that's valid. And what time scale is needed for galactic colonization? Why should that be different elsewhere?
Maybe 10-90% of technological species do make themselves extinct by a nuclear war or an environmental catastrophe. It isn't enough. To explain the Fermi paradox needs a big killer, like an innocent looking physics experiment that sterilizes a solar system.
My point was that we could already be more than a one planet civilization. So all the eggs aren't in one basket.
To be clear: That we already could be an interplanetary culture implies that _if_ there is a big killer that explains the Fermi paradox, it is either big enough to take out a solar system -- or it is behind us.
The next stop for spreading to the galaxy would be to get outside the solar system. The good part is that the Oort cloud etc is a good training stop over. And it would also insulate humanity there from what happens closer to the sun.
(And directly a civilization is interstellar, then it really are multiple cultures (communication lag etc). Those will at least partly be "evolved"/selected for tendency to spread.)
Lots of other people since at least Fermi discussed time scales for spreading in a galaxy, it is an old discussion. If you really can't find good references comment and I'll check the usual suspects for references (centauri-dreams.org).
Ah yes, gamma ray bursts got less common because of changing star formation rates? Really interesting.
I had missed the full argument. [Embarrassing :-)] The one I had seen was that closer to the galaxy centre there would be a higher frequency of supernovas per cubic light year, while too far out there would be too little of the heavier elements from supernovas.
If orion had politically one out and been weaponized it would make current MIRV technology look like a BB gun. Threat of it's development might have triggered a preventative first strike. You can make up all kinds of hypotheticals for either way.
See my parallel answer to 'molbioguy'. I would argue against your point (mainly, you don't need that with icbms + fusion bombs; more than a factor of ten in killing the enemy is a waste of money), but it isn't relevant to my point regarding the Fermi paradox.
