Don't jinx us now, Al.

The nearest planet in the habitable zone (that we know of) is 11.9 light years away.

Assuming that faster than light travel is and always will be impossible, what incentive would any alien race have in colonizing the earth, when you're advanced enough for space travel, planetary resources become irrelevant so other then colonizing for the sake of colonizing there is no benefit to expanding beyond more then a few star systems, and with the astronomical costs of travelling great distances in space there is a massive disincentive to said travel.

The near insurmountable problem of the size of space is why we see no evidence of extraterrestrial life. I refuse to believe that in a galaxy as large as ours (in a universe as large as ours) we are alone. Its just too improbable.

We know of exactly one type of life that has been intelligent enough to build a tool allowing it to leave it's home planet. How is it improbable it is the only one? It's only improbable to someone who has no belief in God and the uniqueness of man.

@ Draug

Do we? I know of no human that has yet to escape Earth's gravity well. We may have gone higher than most creatures but it's not much more leaving our home planet than what your average seagull achieves. Indeed, I suspect that the only terrestrial life that can truly claim to have left Earth is bacteria, and they're not the sort to make a fuss about such things.

"We know of exactly one type of life that has been intelligent enough to build a tool allowing it to leave it's home planet. How is it improbable it is the only one? It's only improbable to someone who has no belief in God and the uniqueness of man."
There are 50 billion planets in our Galaxy and one hundred billion galaxies in the observable universe.

There are only 1811 planets that we have observed on some level, of which 43 meet a majority of the required conditions to sustain life, however we lack the technology to confirm if there is in fact life on any of them.

Even if only 1 out of every 2 million planets contains life, that still means there are 2,500,000,000,000,000 planets in the observable universe that contain life.

Hence why its practically impossible for us to be all alone.

Even from a religious perspective, why would God make the universe so large of only one tiny, tiny, tiny, tiny, tiny dot actually has any meaning?

I'm not an atheist (I'm more of an agnostic/diest then anything), so while I don't necessarily reject the belief in god, I do reject the belief in the uniqueness of man, as the universe is too large for us to be truly unique, that is especially true if the universe is in fact infinitely large.

There is a massive disincentive to inter-stellar travel, especially for the resources needed for colonization, but massive disincentives have really never stopped the human race from doing incredibly great and stupid things, even on a very large scale. In fact, probably the larger the scale, the more of a waste it is. Never stopped us.

You're assuming logic, Fasces...remember P.T. Barnum's favourite saying. Even if it is eventually shown to be not feasible and not to be a good idea for other reasons, it just takes one good sales job.

Why do people want to go on a one-way trip to Mars where they will be living a sparse existence under a media lens and a plastic bubble? If people want to do that, people will want to go to other star systems once it becomes technologically possible and they will find a way to make it happen.

Why? Because that's how we do everything else. There is a massive financial disincentive to keep building things like CERN, but we still do.

I agree with fasces and oct, I this was my argument. And what does the belief in god have to do with anything,Draug?

@Theo: In order for a species to be smart enough to discover a way of interstellar travel, they would also have to be smart enough to know said travel on a mass scale is a bad idea.

In anycase, I'm not claiming they wont colonize, I'm claiming that there is a limit to the amount they can colonize.

I think this is a Malthusian catastrophe (even though I completely reject his theory when it comes to population, I think it applies to space travel).

Because there is a universal speed limit, and that the closer an object gets to said limit the more energy is required to move it, there is a limit on how far a species can travel. Eventually the energy required to travel from one part of the empire to the other would be greater then the possible energy said travel could gather. If said empire continued to expand after that, then eventually said empire would face an energy crisis and collapse.

I guess on this level I agree with the great filter, its impossible to colonize an entire galaxy because a galaxy is too large to be colonized. I'm also not saying that we wont eventually meet aliens, I'm just saying that until we travel to nearby star systems its almost impossible that we will (essentially two civilizations encompassing 10-20 star systems each are far more likely to meet each other then if one civilization encompasses only 1 planet).

"I agree with fasces and oct, I this was my argument. And what does the belief in god have to do with anything,Draug?"
I apologize if my arguments have been used before, I'm not ready to read the 6 pages in this thread

No worries. Just saying I agree with everything you said.

including my religion part? I don't know anyone else who is a deist, so I'd welcome to company in that respect.

Right, Fasces, but it's not a case of going from one end of the commonwealth to the other, it's a case of Earth to Colony A and B. Colony A eventually expands to C and D, and B expands to E and F. And so on. Earthlings may never go directly to E. It wouldn't an empire, just a very slowly expanding bubble of colonized planets.

Much like Earth was colonized from some tribes in Africa. Too long and too expensive a trip for one or ten tribes, but after the first push outwards, the newly formed tribes in the new area push outwards, and so on.

Really, the only limit to expansion is time and the probability that a nearby star will go supernova and wipe out the whole mess.

Yes, I agree. I'm a Darwinist, evolution of man, and a believer that sentient life exists somewhere in the universe, but we are just never going to run into them.

Yea, as theo said, earth will colonize other planets, and those colonies will then colonize other planets and so on. That way we can colonize as much of space as we want.

Another interesting thing would be that because colonizing all of space will only be possible if colonies colonize other planets and so on (like Theo said), humans will change from one star system to another...

Perhaps Humans on Earth will be very different than those on say colony Z, located over 100 light years away. I'm sure that there would be huge genetic changes due to the environment. Bone size and density would be just one example.

@Fasces "In order for a species to be smart enough to discover a way of interstellar travel, they would also have to be smart enough to know said travel on a mass scale is a bad idea."

You're talking about the same species that, for political reasons, built enough nuclear weapons to largely end civilization. That may be considered, by some, an even more of a bad idea.

Go to a TV. Watch some news. Listen to some politicians. The goodness or badness of an idea really doesn't have much of an effect on how well it does, for many things around the world. Just read the forums here, where the elite of the world gather, and see how well this little group can agree on what is a good or bad idea.

Our species may need some maturing before reason and facts rule over emotion and agendas. Then, sure, I may agree with you.

The amount of energy being used by said species will have to increase exponentially as they expand (due to the combination of larger population, increased difficulty in communication, and that the more advanced a civilization is, the larger the population and energy required to sustain said civilization). Eventually they will collapse under their own weight (Its a Malthusian catastrophe, except energy not food)

The walking distance between Africa and Asia is minuscule compared the to distance between planets. Remember its completely impossible to travel between earth and Alpha Centauri (closest star) in less than four and a half years, and not every star is going to contain planets, eventually there will be insurmountable gaps.

"Yes, I agree. I'm a Darwinist, evolution of man, and a believer that sentient life exists somewhere in the universe, but we are just never going to run into them."
that wasn't really my question, I was asking about religion, not about the probability of meeting alien life.

"Our species may need some maturing before reason and facts rule over emotion and agendas. Then, sure, I may agree with you."
yeah, and we're likely thousands if not millions of years away from being technologically advanced enough for intersteller travel.

Gravity is still a more powerful force then our most advanced rockets:
Voyager I, as well as every other space probe that has reached the suns escape velocity (not many have) were only able to do it thanks to a gravity assist on Jupiter. And it will be 120,000 years from now that Voyager 1 will be further away from us then Alpha Centauri.

The amount of energy used will increase proportionally with the number of planets, provided that we are just talking about one-way one-time colonization per planet. Energy use vs. population is per planet and by technology, not over the whole inhabited area, since they would need to be independent.

If we are talking about an empire with trade and cross-planet sales trips and military actions, then I agree with you. The energy wall will hit pretty hard and the empire will fall. But the colonies will still carry on, either colonizing slowly, creating more empires doomed to fail, or whathaveyou.

With a 3 expanding sphere (or even a misshapen blob), it is likely that there will be gaps in places limiting expansion, but very unlikely that the whole area will be an isolated island. Possible, but unlikely.

"The amount of energy used will increase proportionally with the number of planets, provided that we are just talking about one-way one-time colonization per planet. Energy use vs. population is per planet and by technology, not over the whole inhabited area, since they would need to be independent."
And what happens when the central colonies start to run out energy? More people will flee, and each time the gap between settling a system and evacuation said system will narrow.

Wars will eventually be fought over limited space (ie System A has 100 billion people on it, but only the energy to transport 10 billion people out of the system, there is no way to settle who is those 10 billion people peacefully).

Eventually colonial empires, not spanning galaxies but a few systems will spring up and eventually they will fall.

As previously mentioned the galaxy has an estimated 50 billion planets in it, its too big for a single species to get from one side to the other without collapsing on itself.

@Fasces "Gravity is still a more powerful force then our most advanced rockets"

That's because we don't make the rockets more powerful than they need to be. Economics. And gravity boosts also make good economic sense.

If we needed to build more powerful rockets, we know how and have for likely longer than many people here have been alive. We just haven't had the need or desire.


"yeah, and we're likely thousands if not millions of years away from being technologically advanced enough for intersteller travel."

My mother lived on a farm with no electricity, no trucks, and with horses to pull plows. She lived to see people walking on the moon and is still around to see tiny iPods way more powerful than the computers used to get people to the moon. The rate of technological advance in the last hundred years is exponential. Over twenty years ago it got past the point where an expert in a field could keep up with new developments.

I don't think that the rate of technological advance is really understood. I like this article: http://phys.org/news/2013-05-aliens-star-trekfact.html

"As previously mentioned the galaxy has an estimated 50 billion planets in it, its too big for a single species to get from one side to the other without collapsing on itself."

It's too big for a single individual to do so but a species would have a much greater chance of success - For Example - as we seem to be assuming that the space travel itself is feasible (if slow given the size of the galaxy/universe) then an individual of a species living on the "left" of a 500 light year wide empire would be able to get to a planet on his side that is only 1 light away, whereas an individual on the other "side" of the empire would have an extra distance of 500 light years to travel - which might not fit within their lifespan, but nonetheless the species would've reached than planet in part if not whole.

I am not religious, and don't believe in any type of deity. I have no problem with those that do either. If that gets you through the day, great.

I'm hoping that off-planet solar arrays (or some other similar source of power) and effective birth control (societal pressure likely) will settle the need for energy and population wars at some point. If not, then that is one failed planet that will settle things the old-fashioned way and bomb itself back to where population growth can happen again.

Either way, that won't affect growth at the fringes.

I don't see exporting people as a solution to population growth, other than within a star system. http://www.spacedevcoop.com/blog.html

A few people have looked ahead to what a 0-growth society would look like, economically speaking. Companies that rely on continual growth would need to adjust to competing in a 0-sum game, excluding technological advances. It can be done, just investment returns will be a lot lower.

Planets that are full will need to adjust to living in conditions other than continual expansion, or yes, those planets will fall in on themselves. But that's just those planets. Others will adjust. Darwin as applied to planetary societies.

"My mother lived on a farm with no electricity, no trucks, and with horses to pull plows. She lived to see people walking on the moon and is still around to see tiny iPods way more powerful than the computers used to get people to the moon. The rate of technological advance in the last hundred years is exponential. Over twenty years ago it got past the point where an expert in a field could keep up with new developments."
Computers are advanced at unbelievable speeds, but we're stagnating in many areas and many are claiming we are approaching the end of innovation.

The reality is that outside of a few areas we've had very little innovation in the last 40 years.

Sadly, we're fastly approaching a sort of 'limit' to how much we can advance technology. The only thing still left is to improve is computers, and even that is limited by transistors and their heating up. Unless of course we replace transistors with something else.

We went from plowing the fields with animals to tractors in less than a hundred years, but it'll be much more until we replace the tractor. We went from candle light to electricity within a few decades, but we'll continue using electricity for very long, if not forever. The way i see it, technological advancement will slow down, and come to a point where we'll focus more on improving what we have, rather than developing entirely new things. For example, we invented the train long ago, and at the time it really was something new and special. Today though, we're not inventing a new type of transport, we're just improving the same train concept, ex. maglev trains

It'll be a looong while until we have the technology to travel near light speed.

Exactly Fasces

"I'm hoping that off-planet solar arrays"
You're thinking too short term. Eventually solar power wont be enough, I envision in the future that we will literally be extracting energy from the sun.

"will settle the need for energy and population wars at some point"
Then why colonize? There are many many disadvantages (beyond the simple cost) to travelling from one star system to another.

We're not 17th century Europe were people will move to the colonies seeking better life cause when it comes to space, the closer to the center of the species (so long as it has the energy) the better life will be (while interstellar communication is far cheaper then travel, it still has a time limit, that means the center systems will always be more technologically advanced then the ones near the edge.)

Baring energy or population problems there will be no reason to leave or want to leave the central planets.

There will have to be a war or some other crisis that forces an evacuation.

"It'll be a looong while until we have the technology to travel near light speed."
Our cars are no faster then they were 40 years ago.
Our planes are SLOWER then they were 40 years ago. (40 years ago we had the Concorde, which still remains the fastest passenger jet in history)
NASA no longer has any ships capable of transporting men into space but still manages to steal 20 billion a year from taxpayers.

Add on to the problem that due to problems such as the effects of low gravity and cosmic radiation, its currently impossible to safely travel between Earth and Mars, let alone Sol and Alpha Centauri. Granted thats a current, but all the obstacles to travelling between planets are minuscule compared to travelling between starts and galaxies.

"Companies that rely on continual growth would need to adjust to competing in a 0-sum game, excluding technological advances. It can be done, just investment returns will be a lot lower."
Basic economics here: investment returns aren't possible in 0-sum economies. Sure I can still make money, but in order to do so someone would have to lose money, in the long run it will balance out, so that neither profit nor loss becomes possible.