Age of the Galaxy in MM

<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">But without support from the home world able to send knowledge, resources, and expertise, all colonies would soon lose their technology<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">
I couldn't disagree here more. My view is that once an expedition leaves its home planet all it "needs" from its home planet is "postcards, Christmas cards, pictures of the latest Miss Alienverse winner, etc.". Essentially, it takes with it all the accumulated knowledge of the home planet and acquires all its raw materials from the new place. What could they possibly need from the home planet? Iron ore? Water? Presumably robotic assemblers would build all the necessary machinery and all they would need is programming and a human start to beginning replicating more assemblers and everything else that the "alien-humans" needed.

A colonizing expedition would consist of dozens of large ships with several thousand people on each. So that, on arriving at the new solar system, all they must do is continue to reproduce and gradually setup on one of the planets orbiting the new sun. They may consume 1000 years, 10,000 years or 100,000 years developing their new "home" ... then ... they send out 2 new colonizing expeditions of the same sort. To obtain a rough estimate of galactic colonization time multiply the average time between successive expeditions by "about 38" (i.e. how many doublings to cover the 100 billion potential solar systems) then add to this the diameter of the galaxy divided by the average velocity of the expedition ships. You can see that the time spent developing in preparation for sending out the next expeditions is all but irrelevant.

Thus, at 1/100 c as the expedition velocity and 100,000 years to send out the another 2 expeditions you get a colonization time of around

[(200,000 light years) / (1/100c)]
+
[38 x 100,000 years]
=
23,800,000 years to colonize the whole galaxy

And ... that's the slowest colonization time I can imagine. And I "fluffed" the math a bit so as not to confuse the issue. It's actually a fair amount less than that. An actual colonization time would be more like 5-10 million years I expect. Then figure that colonization starts from several thousands of different planets with indigenous populations and you see why Fermi said, "Where are they?".

---

I saw a thing on Discovery or History channel some months ago about the possibility that the human race was down to only several hundred members due to some cataclysm thousands of years ago (bolstered by genetic evidence). They came back just fine with no significant technology and here we are just about ready to send out an "expedition" in another thousand years or so.

I submit that there is no conceivable scenario short of total galactic explosion (which has not yet happened ;o) ... which would totally annihilate an advanced civilization which had spread itself out by colonizing the galaxy. In fact, there is nothing known in the universe which is any threat at all to the survival of intelligence over the span of say, the next 2 or 3 billion years or the past 2 or 3 billion years. Once firmly established, civilization is a permanent feature of this galaxy (on at least the scale of a few billion years).

<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by tvanflandern</i>
<br /><blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by EBTX</i>
<br />From my perspective, there is nothing conceivable that could "kill off" a civilization which had taken to colonization in a big way. It would just continue indefinitely.<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">I am having no trouble conceiving several hazards that could wipe out a civilization that has colonized. Some leading prospects are supernova explosions and gamma ray bursts. Whatever is producing the electron-positron annihilation spectrum near our galactic center is probably another. On a longer-term perspective, once the whole galaxy dissolves or explodes, it is sure to be rough going for even the most advanced civilization without energy or resources.

<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">but they don't disappear. ... To remove all traces of a dominant civilization would require that they "commit suicide" for there is nothing to pry them out of the planets which they've occupied ...<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">You missed my point about the number of individuals required to maintain a technology. All planets are subject to natural hazards. Local ones here are tornados, hurricanes, earthquakes, tsunami, volcanoes, floods and fires. Planetary disasters include asteroid and comet impacts, giant solar flares, long-term changes in solar luminosity, planetary and moon explosions anywhere in the system, cosmic ray events, magnetic pole reversals (our radiation shields may go down), passage through giant molecular clouds, etc. Biological disasters include wars, plagues, nuclear power plant meltdowns, industrial changes in atmospheric gases, flooding and violent weather induced by polar cap melting, etc.

The point is that, while none of these things are guaranteed to wipe out civilizations completely, they do reduce the number of individuals to below the threshold for maintaining a technological civilization. Once the technology is gone, the species is essentially reset to where humans were roughly three million years ago -- struggling to survive and passing along legends of a "Garden of Eden" and a "golden age" to their offspring.

<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">So even if a dominant culture did manage to leave a planet (completely), if there are thousands of other planets with indigenous life on them, that abandoned planet would be recolonized in about 3 nanoseconds ... after all ... it's available once again.<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">You are just thinking of how easy it is to reproduce. But without support from the home world able to send knowledge, resources, and expertise, all colonies would soon lose their technology, which makes them unable to spread further unless/until they evolve back up the ladder, can support a stable population of perhaps billions, and rediscover technology and space travel. Depending on the hostility of the environment, that may or may not ever happen. But there are probably thousands of colonies that simply die out for every one that survives a lengthy series of natural disasters and makes it back to interstellar travel -- a lofty place we ourselves have not yet achieved. But for long-term survival, we must reach the point where we are sending viable populations with sufficient genetic diversity to many worlds and continuing to supply them with technology support until they each reproduce many millions of individuals and become self-supporting.

I'd give long odds against that happening very often. I'd give longer odds against reaching the level of a self-sustaining intergalactic civilization. -|Tom|-

<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">

Nowadays, you can carry the whole library of congress on
a laptop so the human race can never be in danger of losing
their technology . And getting updates on current technology
while in space is a simple matter with satellite transmissions.
So, I don't see how difficult it can be to maintain 21st
century technology. All you need is one person who can
read.

Imo, the only real problem in space colonization
is that of natural resources. We have to be able to produce food,
water, oxygen, fuel, and shelter using the stuff available at the place of colonization. We can easily improvise for fuel and shelter but would be hard-pressed to find a constant
supply of organic matter, water and oxygen.

Fusion technology has to be perfected first.

The Big Explosion Corrolary to MM



A long time ago, in a super-megacluster of galaxies that no longer exists ...
(oh, and some parts of which were far far away ...)


There used to be a Super-Megacluster Of Galaxies where we are now.

It was BIG. Several trillion light years in diameter.

It was small, however, as super-megaclusters of galaxies go. Tiny really in comparison to most of them.

Then, something happend.

It went pop.

Maybe all at once, maybe in a chain reaction. First this galaxy cluster, then that one. Pretty soon clusters of clusters were burning. Before you could say "the Big Bang is never going to happen" a gazillion and forty two times, the entire Super-Megacluster was gone.

===
((
So, in a way, the Big Bang did happen. Only it was an "ordinary" explosion in space. Not an explosion of space. The observed CMBR is the remnant of that explosion of the super-mega-cluster of galaxies. And the approximate center of that explosion is HERE. And everything we see out there appears to be moving away because it is. As a result of that Big Explosion.
))
===


Anyway, all the people living in this SMOG burned up. Entire families, some with members living in hundreds of different galaxies, wiped out in just a few billion years.

Some of them had nanotech. They could EACH carry the combined knowledge of EVERYONE that had ever lived in a little thumb drive. Litterally. In their thumb. (Of course, some of them didn't have thumbs, so there was a problem until the tentacle drive and the pseudo pod drive were invented.)

And each person could manufacture ANY thing that had ever been designed just by thinking about it. The nano-gizmos in their thumb would start multiplying. In a few milliseconds there were enough to go foraging for atoms and molecules and energy to build the thing that had been thought. Food, clothing, shelter, transportation. Sex toys were popular. And medical products that kept them young. Forever, as far as they could tell.

A few sparklies in the air and SHAZAM! It was really cool.

Everyone believed that they were not just imortal. They were also invulnerable. As a group of species. As individual species. And as individual persons. Because of the medical products it actually became physically impossible to kill someone. At least for more than a few days.

In a society where murder is no longer illegal, and has become no more than a (bad) practical joke, things can get sort of ... weird.

((
Even if a single person became stranded in a desert solar system with no planets, moons or asteroids, that person could use their nano-critters to collect particles of the solar wind and build a space ship to rescue themselves. And food to sustain themselves for the few hours it would take to build the space ship. And a home theater to keep from getting bored.
))

===

So like I said, everyone believed they were safe. And had good reason to believe this.

But they were wrong.

In an infinite universe, there are big bangs.

And then there are BIG bangs.

if i may also give my 2 cents in as well. i look at each individual galaxy as a female egg and each star as sperm,therefore this leads me to think that each galaxy is probably capable of producing one being each with probably the odd exception of one or two more. now if you take into concideration of how many galaxies there are thats either millions or billions of civilizations,well thats a huge amount of being potential,now their biggest problem in space travel would be traversing not only their own galaxy but then to our own,thats got to take an enormous amount of time. and as well not all galaxies will have life, for some of the reasons mentioned above.

<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by 1234567890</i>
<br />Nowadays, you can carry the whole library of congress on
a laptop so the human race can never be in danger of losing
their technology. ... All you need is one person who can read.<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">Is that so? Suppose you are that one literate person. Who will teach you how to use the laptop? Or how to access its knowledge base? Or language, math, history, science, and logic on top of all the food, clothing, and shelter skills you must have?

Then one day the laptop needs technical support. Did you learn how to be your own tech support guy before it gave out? Do you have spare circuit boards with you to do the repairs? Or will you simply take a few crash courses in tool design, manufacturing, electronics, circuitry, miniaturization, electron microscope design, and all the other contributing fields so you can make your own spare parts and install them?

And while you are picking up all these skills, who will be learning health, medicine, and surgery, and developing all the machinery for diagnosis and tech-aided medical procedures to keep you (and any companions) healthy? I could list thousands of similar examples of things that would be needed to maintain a technological civilization, couldn't I?

In truth, if we consider any expert in any area of human interest, some of these experts are truly unique. Others have a few peers, but only a handful. In still other cases, hundreds, thousands, or millions may have developed a particular skill, such as building and maintaining the internet for the whole society. But when there are many replaceable individuals, it is because there is a need for many, not because they are redundant.

Now suppose a major asteroid strike occurs in middle of your civilization. The immediate blast kills millions, including many irreplaceable people. It also knocks out all computers from the electromagnetic pulse, and all communications are disrupted. If it is a big enough impact, most entire species go extinct during the global fire that ensues. That is followed by a prolonged nuclear winter or even an ice age. Food is extremely scarce, the weather is intolerable, and the organization of society has broken down. Your Library of Congress becomes a luxury available to only a few survivors, with little of use in connection with immediate survival issues. Offspring are no longer tutored in the arts and sciences, but rather in how to hunt and farm and find/build shelters in caves and how to make fires from sticks. Because resources remain scarce, conditions do not improve. In a few generations, no one has any further use for experts in rocketry or space travel or Mars rovers or home theaters or stock market investments or most book knowledge. In a few more generations, the past becomes a fantasy and fades into legends in the face of a harsh reality.

The lesson of a variety of books written in just the last decade or so is that civilization apparently proceeds in fits and starts, frequently set back or wiped out by natural and man-made disasters. Several authors have stressed the theme that apparently, several ancient civilizations on Earth were quite advanced before getting k.o.-ed. Apparently, our success is more due to a fortuitous gap in such disasters than it is to our "smarts". Our current "golden age" could end forever later today. Any anyone still claiming that nothing could drive us extinct because we could always colonize other planets would be judged insane. -|Tom|-

Wait a minute...did somebody mention ENTIRE GALAXIES EXPLODING?

Would you mind elaborating on that?