Why We Haven't Met Aliens Yet

[Roboramma]

Given the propensity of the universe to do nasty things to planets, and the inherently delicate nature of life as it exists today, I find it rather naive to expect a species like ourselves to last much more than a few hundred thousand years, and likely a lot less than that.

Given the propensity of intelligent life to adapt to new environments, I think it's naive to expect a species like ourselves to do anything but expand.

As our technology develops and the resources at our disposal grow, our ability to deal with bigger and bigger challenges will grow in the same way. The ways in which we could have gone extinct 100,000 years ago were far more numerous, or at least more likely, than those that exist today, even including those that are potentially of human origin.

But perhaps I'm putting less stock in human extinction by nuclear war than I should. I don't think so but it's possible.

 

[Stomatopoda]

There's also the possibility that any civilization approaching relativistic travel capabilities will be wiped out, since the cost of not wiping them out is the non-zero possibility of them wiping you out, as no level of technological advancement past the R-bomb ever grants immunity from it. There could be untold numbers of alien civilizations cowering in silence across every galaxy.

 

[Roger Ramjets]

The ways in which we could have gone extinct 100,000 years ago were far more numerous, or at least more likely, than those that exist today,

The difference is that today we are capable of changing the environment far more rapidly than in the past. We are now in a state where evolution is too slow to adapt, and we must use technology to keep going. Unfortunately this is not coupled with sufficient knowledge and foresight to avoid digging a hole that we cannot get out of. whether it's bacteria growing in a Petri dish, or humans populating the planet, exponential growth cannot be maintained forever.

We have used technology to exploit non-renewable resources and push our population well beyond our ability to sustain it. Some people think that we can fix this like we did in the past - by colonizing new lands. But there isn't any 'new' land left on this planet. So why not just go to another one? Why not, indeed. One obvious reason is that we don't have enough resources left here to get to there. Another one is that it would probably be far safer and easier to work with the habitable planet we already have, rather than hoping that we can find, get to, and survive on an unknown quantity somewhere else in the galaxy.

Wow, I'm just surprised because we have such disparate views of the human future. I don't really see how that is at all likely.

In 1969 we put a man on the Moon. 42 years later, and...

Our civilization is built on fossil fuels and and other resources which we are consuming faster than they can be replaced. If we want to maintain and/or improve our lifestyle and technology, then sooner or later we must transition to efficient use of renewable resources.

The alternative is to just carry on with Business As Usual and run out of resources, which will almost certainly damage the delicate infrastructure required to keep developing advanced tech. Also hanging over us is the impact of Global Warming, which will only make things worse.

And just in case you think that Western civilization is robust enough to take these challenges in its stride, let's not forget that over 70% of the World's population still look up to some imaginary deity to guide them. Unless we get a massive increase in rationality real soon, I'm afraid that the chance of avoiding the mess we are getting into is slim.

Now I'm not saying that we won't avoid disaster, but the effort to do so will almost certainly preclude any major plans to expand into space.

 

[Roboramma]

The difference is that today we are capable of changing the environment far more rapidly than in the past. We are now in a state where evolution is too slow to adapt, and we must use technology to keep going. Unfortunately this is not coupled with sufficient knowledge and foresight to avoid digging a hole that we cannot get out of. whether it's bacteria growing in a Petri dish, or humans populating the planet, exponential growth cannot be maintained forever.

But human population growth isn't going to remain exponential anyway, so why bring that up? The limiting factor isn't the failure of resources, but instead people choosing to have fewer children.
For instance:

Or: http://en.wikipedia.org/wiki/File:World-Population-1800-2100.png

We have used technology to exploit non-renewable resources and push our population well beyond our ability to sustain it. Some people think that we can fix this like we did in the past - by colonizing new lands. But there isn't any 'new' land left on this planet.

The other option is to make use of currently available resources in new ways. For instance, as we run out of fossil fuels, we can switch to nuclear power.

So why not just go to another one? Why not, indeed. One obvious reason is that we don't have enough resources left here to get to there. Another one is that it would probably be far safer and easier to work with the habitable planet we already have, rather than hoping that we can find, get to, and survive on an unknown quantity somewhere else in the galaxy.

In 1969 we put a man on the Moon. 42 years later, and...

The cost of getting into space relative to world total economic product has declined dramatically since 1969. Your post makes it sound like the opposite is the case.

Our civilization is built on fossil fuels and and other resources which we are consuming faster than they can be replaced. If we want to maintain and/or improve our lifestyle and technology, then sooner or later we must transition to efficient use of renewable resources.

Nuclear can't be considered renewable, but it's an entirely viable replacement of fossil fuels.

Moreover, making use of off-world resources isn't a "colonize other planets or just stay on earth" either or option. We can also harvest the resources present in space without living and breeding there.

 

[nvidiot]

The cost of getting into space relative to world total economic product has declined dramatically since 1969. Your post makes it sound like the opposite is the case.

Getting into space is different from going to the moon. How much do you think it would cost to send a manned mission today? And how difficult would it be to get the political will to do so?

 

[Roboramma]

Getting into space is different from going to the moon. How much do you think it would cost to send a manned mission today?

As a proportion of total world economic production, less than the Apollo program (as a proportion of total world economic production at the time).
In real dollars? Also less than the total cost of the Apollo program.

And how difficult would it be to get the political will to do so?

That's rather a different question. But I don't see how it applies: there's no reason to send someone to the moon. There wasn't much reason to do so then either, though it was a glorious stunt.

 

[RobDegraves]

A bit of nitpicking...

I disagree. Two immediate examples come to mind. Radar is not going away and neither are satellite communications.

Neither are likely to be noticeable from another star... and lasers are a more likely means of communicating with satellites in the future.

But human population growth isn't going to remain exponential anyway, so why bring that up? The limiting factor isn't the failure of resources, but instead people choosing to have fewer children.
For instance:

That is not a certainty by any means. It's hard to project but even if the growth is not exponential but simply continues growing, we cannot absorb much greater numbers.

Also...

Nuclear can't be considered renewable, but it's an entirely viable replacement of fossil fuels.

You vastly underestimate the problem.

1. Fossil fuels currently account for 86 % of our energy generation. It will not be easy to replace that.

2. It isn't just about energy. How about plastics? Rubber? The covering on electric lines, oil to lubricate nearly all the engines in the world.. etc. What will you use to replace plastics?


Frankly, I consider over population to be one of our most pressing issues.

 

[Stomatopoda]

Replacing fossil fuel plants with nuclear wouldn't solve all our problems, but it would buy us a lot more time to do so.

 

[Roboramma]

That is not a certainty by any means. It's hard to project but even if the growth is not exponential but simply continues growing, we cannot absorb much greater numbers.

But population is projected to decline in the long term. If you're saying "yes, but it's possible that it won't", that's fine, but it's also possible that a very large asteroid will strike the earth next year. What's likely? That's what those projections are about.

You vastly underestimate the problem.

1. Fossil fuels currently account for 86 % of our energy generation. It will not be easy to replace that.

I'm not suggesting that it will be, only that the problem is soluble. And as the price of fossil fuels increases, other energy sources will become more economic, fueling their growth.

2. It isn't just about energy. How about plastics? Rubber? The covering on electric lines, oil to lubricate nearly all the engines in the world.. etc. What will you use to replace plastics?

As long as you've got the energy there are other ways to produce all those things.

Frankly, I consider over population to be one of our most pressing issues.

Me too, and I think that there are some major negative repercussions that not only we will have to deal with, but which we already are facing because of that. However, I don't think it will lead to the destruction of our civilization.

 

[WhatRoughBeast]

Nuclear can't be considered renewable, but it's an entirely viable replacement of fossil fuels.

If we find an economical way to separate uranium from seawater, it certainly is renewable. Weathering of rock, particularly granite, constantly replenishes the level of uranium in the sea, and on quite a massive scale.

 

[Gawdzilla Sama]

If you guys really want to meet aliens come by my cousins' house, I'll introduce you.

 

[Roboramma]

If we find an economical way to separate uranium from seawater, it certainly is renewable. Weathering of rock, particularly granite, constantly replenishes the level of uranium in the sea, and on quite a massive scale.

In fact, we do have an economical way to separate uranium from seawater: just not in comparison to mining it from the earth. But the price of uranium from seawater is not enough to even affect the price of nuclear power.

In other words, it's not worth it to get uranium from seawater now because we've got a cheaper way of getting it, but as other sources run out, changing to getting it from seawater, even using currently known techniques, won't affect the price /kwh.

http://en.wikipedia.org/wiki/Uranium_mining#Recovery_from_seawater

One method of extracting uranium from seawater is using a uranium-specific nonwoven fabric as an absorbent. The total amount of uranium recovered from three collection boxes containing 350 kg of fabric was >1 kg of yellowcake after 240 days of submersion in the ocean.[8] According to the OECD, uranium may be extracted from seawater using this method for about $300/kg-U.[9] The experiment by Seko et al. was repeated by Tamada et al. in 2006. They found that the cost varied from ¥15,000 to ¥88,000 (Yen) depending on assumptions and "The lowest cost attainable now is ¥25,000 with 4g-U/kg-adsorbent used in the sea area of Okinawa, with 18 repetitionuses [sic]." With the May, 2008 exchange rate, this was about $240/kg-U.[10]

Of course, my post is based on the assumption that the above experiment was valid and that this methodology will consistently give similar results, but it should be pointed out that the price/kg of extraction in a small scale experiment is likely to be much higher than the price/kg after major development: ie. this price is likely much higher than what we'd expect if the technology were implemented on a large scale.

 

[Donn]

Neat thread.

Hypothesis:
If there was a single civ that invented FTL (by any means) within the last <x> years then there would be detectable evidence on the universe by now.

If a civ has FTL, it has other advanced tech. With that they would begin moving and colonizing. The pollution from their various physical activities would paint a picture across the sky.

We don't see anything like it in our observations, ergo there are no vast civs, ergo there are no FTL drives (at the very least.)

Assumption that this civ is similar to humans: Survival. Population, pressure, politics, escape, spread, resource gathering, building, experiment, war, etc.

Where are the highways? Even the fabled 'sub/hyper space' must leave something at either end.
Where are the lights on planets at night?
Where are the Dyson spheres and Orbitals (Rings)?
Where are the vast battlefields that differ from their backgrounds?
Where are the mining operations that tackle entire gas clouds?

I liken it to the influence man has had on Earth in only a few thousand years. Imagine us with FTL unleashed on the galaxy? It would not be pretty.

What do you think?

 

[Gawdzilla Sama]

Anybody else remember that the story "The Day The Earth Stood Still" was based on had the robot as the master and the human as the servant?

 

[tsig]

I doubt if we're alone. Our signals may not have reached an advanced civilization or our signals are misinterpreted or the civilization may be too primitive to have radio. There may even be a civilization that knows we're here but isn't interested in us at all.

Maybe the signal got there and the bombs are on the way.

 

[Soapy Sam]

Maybe the solar system is ringed with "Keep out!" signs.

 

[Gawdzilla Sama]

Maybe the solar system is ringed with "Keep out!" signs.

Keep Oort!

 

[dafydd]

The first TV signals to go into space were from German television in 1935. No wonder the aliens are avoiding us.

 

[Corsair 115]

That argument depends on the average lifespan of civilizations also being small. If we begin to colonize other worlds, I find that extremely unlikely.

You're still relying on the idea, it seems to me, that each galaxy must be home to dozens, if not hundreds or even thousands of civilizations. That is pure speculation. It could just as easily be only one civilization per galaxy, in which case we are it for ours. Given the distances to other galaxies, barring some incredible breakthroughs in faster-than-light travel, we'll never meet civilizations from other galaxies. (Consider: at the mind-boggling speed of 100,000 times the speed of light, you could cross from one side of our galaxy to the other in under a year. It would take you twenty years at that speed to reach the next nearest galaxy to ours.)

But even at only one civilization per galaxy on average, there'd still be something around 100 billion civilizations in the universe.

 

[Roboramma]

You're still relying on the idea, it seems to me, that each galaxy must be home to dozens, if not hundreds or even thousands of civilizations.

No, I'm relying on the idea (as posted upthread) that once they get going civilizations expand throughout the galaxy. Thus, one civilization will fill up the galaxy in something on the order of tens of millions of years.

This then requires only one civilization (other than us) in our galaxy, as long as it arose on the order of tens of millions of years ago.