The Fermi Paradox ...life in the galaxy explained

[Daehawk]

Thanks for posting that link last year btw. I missed it at the time, and it's a great read.

Sure thing Tilt....glad you enjoyed it

[noxiousdog]

I think calling galactic expansion "easy" is a non-standard point of view. I understand that motivation would seem to be high (we're all orbiting something which won't last forever), but space is VAST. What was the analogy in the article I linked? If Neptune's orbit was the size of a quarter, then the nearest star is a football field away? (And the nearest known habitable star is, what, 5× that?) In the face of that obstacle, El Guapo's objections, and time scales measured in billions of (earth) years, maybe motivation isn't actually all that high?

We have the theoretical capability to colonize the galaxy now. In 100,000 years? Easy. It will take many generations, but still doable.

And again, it doesn't have to be high. It can be very rare as it only takes one.

If we want to get into guesses, I would bet intelligent beings are far more likely to transcend into cyborgs/computers.

[Isgrimnur]

We have the theoretical capability to colonize our solar system right now. There's no way to export enough mass to guarantee that an interstellar mission would be able to set up a self-sustaining colony on another world. In the event that Proxima Centauri held a hospitable planet, mere communication takes 4+ years for one-way messages.

[The Meal]

We have the theoretical capability to colonize the galaxy now.

I don't see it that way, and I don't think the challenges to get there (in say, 100,000 years) are non-starters. I know riding the solar wind to get us to the edge of our solar system seems doable, but how much gas (uranium, etc.) are we spending to begin the galactic journey out to the next habitable star? Is the ion drive sufficient?

And again, it [motivation] doesn't have to be high. It can be very rare as it only takes one.

Agreed. Though I'd add the (tiny) caveat that it'd only take one *before* us.

If we want to get into guesses, I would bet intelligent beings are far more likely to transcend into cyborgs/computers.

Can't argue with that (especially considering the AI article which came through here a month or so ago).

[edit: missed a tag]

[Holman]

It could be that the truly depressing thing about Fermi is this: we don't know which scenario is accurate, but nearly all of the scenarios turn on the fact that space is so vast. For the vastness of space to matter in this discussion, that vastness must be an obstacle to colonization/travel/communication. If vastness is an obstacle, it's because time and distance never cease to be limiting factors for civilization.

So, no matter which Fermi scenario we inhabit, it seems likely that faster-than-light travel and communication are impossible not just at our level of technology but for all civilizations at all levels of technology. That's a real bummer.

[The Meal]

Travel? Agreed.

Communication? Show me our FTL-receiver.

[noxiousdog]

Travel? Agreed.

Communication? Show me our FTL-receiver.

You don't need that to colonize the galaxy though. A far flung galactic empire would surprise me. A civilization giving off radio signals? Not so much.

[BooTx]

I'm not sure why we would assume that a civilization would eventually colonize substantially the whole galaxy given enough time. If the speed of light is a hard physics rule that can't be overcome with sufficiently advanced technology, that means it would take enormous amounts of time to colonize even relatively near worlds, to say nothing of worlds on the other side of the galaxy. It may well be possible for a civilization to do that over enough time (say by the self-replicating colonizers that the original article mentions), but what reason would a civilization have to do that? You would spend an enormous amount of resources building the colonizer, send it out...and then never hear anything from the colony at least until long after everyone alive at the time is dead and gone. You might not be able to communicate effectively with other colonized worlds, probably can't get resources back.

It might make sense to colonize a couple worlds just to avoid the risk that the entire species gets wiped out by some cataclysmic event impacting the original world, but why would we assume that they would decide to colonize the whole galaxy?

A couple things. First, "until long after everyone alive at the time is dead and gone" is a huge and terrible assumption. Not only do you not know what form of communication they may be using, but who knows what the lifespan of another species might be? It may well be indefinite, particularly if they're so advanced and have mastered genetic engineering (or transferred their consciousness into machines).

Also, one civilization doesn't necessarily have to colonize the entire galaxy in this example. The point is that it's doable within a small (relatively speaking) time frame, and if intelligent life is somewhat common, then you have potentially millions of them doing the same thing around the Milky Way. So even if individually they didn't spread far, collectively they would have.

Which leads me to my last point, which is that from the knowledge we have of all life on Earth, it is a pretty safe bet that other life will follow similar colonization patterns (in other words, they'll pretty much spread everywhere they can).

[UnicornPoint]

Another way to think of it, is that the strength of a radio signal will be only 1/4 as great once you are twice the distance from the source. At ten times the distance, the strength of the signal would only be one hundredth as great.

Because of this inverse square law, all of our terrestrial radio signals become indistinguishable from background noise at around a few light-years from earth. For a civilization only a couple hundred light-years away, trying to listen to our broadcasts would be like trying to detect the small ripple from a pebble dropped in the pacific ocean off the coast of California – from Japan.

http://zidbits.com/2011/07/how-far-have ... rom-earth/

[gameoverman]

It has nothing to do with how long we've been looking but everything to do with how long other civilizations should have existed. Given that ours is a young star, there should have been many civilizations that have arisen.

And there is no reason to believe that's not the case. Because we don't detect them? That's partly my point, us detecting anything from aliens is not a given. Fermi, and those that consider that question, start with some kind of assumption that we have the tools and tech to see what there is to see. We don't. Once upon a time infrared didn't exist as far as humans knew, now we can 'see' things in infrared. Some future tech might show us a Lovecraftian reality, with alien things here on this planet all along and we never knew it.

I could just as easily say that your position is self serving because you want to not make humans special. See how easy that is? Point is, I don't get the sense that most professionals involved in this discussion care much one way or another. In fact most probably leans towards the idea that humans aren't special.

That doesn't really work because I'm the one saying we have a long, long way to go before we can say we've detected even the thousandth part of what exists. People like you are the ones saying we've looked everywhere and they aren't there. It's on you guys to present a convincing argument that we even know what to look for, much less where to look.

Again, you miss that point that given the young age of our star, there should have been many powerful civilizations that would have arisen before us, and they should have left obvious signs of their existence.

Huge assumption there on your part. That they'd have to leave obvious signs of their existence. Considering that we are talking alien intelligence, what makes you think they 'have to' do anything? What is 'obvious' evidence of alien existence? I bet you are using those words in a human centric way, which is why I think it's meaningless and self serving.

The Great Filter can be more than one. It's a concept that as intelligence grows, those intelligent beings are exposed to some limiting factor that less intelligent beings would not face. For instance, humans often die from causes that tigers don't face, like war. It stands to reason if you have ten different alien races, you'd have ten different Great Filters. So it's not that all alien intelligences get wiped out by the same filter, it's that the end filter is shaped by the nature of the individual alien race. Each intelligent alien race custom designs its own end game, hence 100% efficiency.

[GreenGoo]

A couple things. First, "until long after everyone alive at the time is dead and gone" is a huge and terrible assumption. Not only do you not know what form of communication they may be using, but who knows what the lifespan of another species might be? It may well be indefinite, particularly if they're so advanced and have mastered genetic engineering (or transferred their consciousness into machines).

...

Which leads me to my last point, which is that from the knowledge we have of all life on Earth, it is a pretty safe bet that other life will follow similar colonization patterns (in other words, they'll pretty much spread everywhere they can).

If they are immortal what evolutionary pressures are pushing them to spread?

We've been to the moon a couple of times. We haven't gone back. Why not?

The problem with these scenarios is that literally our imaginations are the limit, and even though our imaginations are pretty good, there are going to be (or possibly be) scenarios we can't even imagine.

It's a fun exercise, but in the end no satisfaction will come of it, because until we know, we don't know. Sorta like God.

[The Meal]

Travel? Agreed.

Communication? Show me our FTL-receiver.

You don't need that to colonize the galaxy though. A far flung galactic empire would surprise me. A civilization giving off radio signals? Not so much.

Nor do I think a hypothetical non-single-solar-system alien race would need FTL travel or communication. I was responding to the post preceding mine which implied that our current state of affairs implies no FTL travel (to which I agree) or FTL communication (to which I say, we wouldn't know).

[BooTx]

If they are immortal what evolutionary pressures are pushing them to spread?

If humans gained immortality do you really think they'd stop spreading? I think it would only increase the rate (exponentially in the long run).

In any case I certainly don't think having an indefinite lifespan would halt the spread of a civilization. There are plenty of reasons to do so. The collection of resources, knowledge, et cetera. Hell they may just be dicks out looking for a trophy to hang on their wall.

We've been to the moon a couple of times. We haven't gone back. Why not?

Because it's difficult and cost-prohibitive when weighed against the potential gains, I suppose. Ask the world governments. For the record, we've had six manned moon landings, which isn't too bad when you consider how ridiculously inexperienced we are with space travel.

It's a fun exercise, but in the end no satisfaction will come of it, because until we know, we don't know. Sorta like God.

Or maybe some satisfaction will come of it. You know, because it's a fun exercise. And fun is satisfying.

[TiLT]

There's a huge leap of logic here that most of you seem to be making (including the author of the article). What exactly would these advanced civilizations send out that we would be able to detect? We can barely detect planets in nearby star systems, and only by studying orbital patterns and similar things. How could anyone expect us to be able to detect the presence of an alien race thousands of light years away? We're listening to radio, and as pointed out earlier, radio is extremely ineffective over the distances needed for it to matter. Half the Milky Way's stars could be covered in Dyson Spheres for all we know, and we might just think they're black holes.

Our capability to detect and discover other species is so limited right now as to be almost non-existent. An alien species could be on our doorstep, and we'd be none the wiser.

Unless the aliens make contact on their own (and why would they?), we're essentially blind right now.

[LawBeefaroni]

If they are immortal what evolutionary pressures are pushing them to spread?

The fundamental pressure. Reproduction. Being immortal doesn't mean you don't want offspring nor does it mean that the resulting genetic roll of the dice isn't beneficial to the species.

[Jeff V]

Sagan summed some of this up far more concisely, I think in Demon Haunted World. He explained how life could be ridiculously ubiquitous (every solar system) but even with generous estimates on how many might evolve intelligent life, there are many reasons we haven't seen evidence yet (and may never). Some were included in this article, some, not really. Off the top of my head (and I read this many years ago), one of the big ones is time line. Earth is about 5 billion years old out of a 13 billion year old universe and the human race has only been cosmically aware about a comparative nanosecond. Great species could have come and gone elsewhere in the galaxy; at the moment, there is just nothing happening close enough to lock on to. As mentioned in this article, technological compatibility could also be a major issue...one of Sagan's big delimiters was the odds that another species is near-equivalent in their current technology state as us.

Given the distances though, only civilizations within about 100 LY would even possibly be alerted to life here; assuming they were looking for and could decipher radio signals. That's a fairly tight locality, and it could be that interstellar travel is simply not feasible for any creature no matter how advanced. Or it could be an invasion fleet has been launched but just hasn't arrived yet. I'd bet, however, that speed of light is a very limiting factor. Look at the other side, if we picked up a signal sent 100 years ago, a response would take another 100 years to get back to the sender and so on. Just think how technology advanced over the past 200 years (hell, consider how it advanced in just the past 20 years!) and it's not hard to see how impractical this could get.

Until certain physical limitations can actually (not theoretically) be overcome, the rarest thing of all might be communication between two intelligent species. It might be too optimistic to think that barriers to interstellar travel and communications are able to be surpassed through sufficient technological advancement (and that seems to be a depressing outcome many don't want to consider).

Enjoyable article, though.

[noxiousdog]

There's a huge leap of logic here that most of you seem to be making (including the author of the article). What exactly would these advanced civilizations send out that we would be able to detect? We can barely detect planets in nearby star systems, and only by studying orbital patterns and similar things. How could anyone expect us to be able to detect the presence of an alien race thousands of light years away? We're listening to radio, and as pointed out earlier, radio is extremely ineffective over the distances needed for it to matter. Half the Milky Way's stars could be covered in Dyson Spheres for all we know, and we might just think they're black holes.

Our capability to detect and discover other species is so limited right now as to be almost non-existent. An alien species could be on our doorstep, and we'd be none the wiser.

Unless the aliens make contact on their own (and why would they?), we're essentially blind right now.

This is ridiculous every time I hear it. Newtonian physics isn't going to stop working. Except in the case of some technological singularity that transforms a civilization into energy, there's going to be some form of recognizable signature. You can't hide a civilizations energy signature unless you're in a Dyson sphere, and then there's going to be a hole where the sun should be.

We can only detect planets in nearby systems because they don't give off energy (and yet we still can). If something gives off energy, it's easy to detect even at the edge of the universe.

[Jaymann]

Also I agree with Hawking and Sagan that actively attempting to contact alien species is incredibly stupid and reckless.

I do not agree with this assessment. I don't think any civilization sufficiently advanced to overcome the huge obstacles discussed in this thread would have any interest in stomping on our comparative ant hill. Much more likely is they would hope to preserve a rare intelligent species.

And I crack up at all the "battlefield earth" fantasies. Any actively hostile galactic aliens would just slip us a nano goo mickey and we would never know what hit us.

[Rip]

There is no such thing as time.

Just a bunch of Nows in Platonia.

[The Meal]

Name the things which generate energy which we cannot detect.

[msduncan]

Also I agree with Hawking and Sagan that actively attempting to contact alien species is incredibly stupid and reckless.

I do not agree with this assessment. I don't think any civilization sufficiently advanced to overcome the huge obstacles discussed in this thread would have any interest in stomping on our comparative ant hill. Much more likely is they would hope to preserve a rare intelligent species.

And I crack up at all the "battlefield earth" fantasies. Any actively hostile galactic aliens would just slip us a nano goo mickey and we would never know what hit us.

I don't agree. Species that conquer their evolutionary trees are going to be predatory. Species that expand beyond their systems are going to be aggressive. They may not be spit slavering aggressive but they are going to be aggressive in terms of civilization and expansion. They may not even recognize us as worth the trouble of courtesy as they grab whatever resource on our planet turns out to be valuable to them. Hopefully it's not our women. It might be white quartz for all we know. Common here but rare everywhere else.

We are infants. Nay, we are fetuses in the Universe.

[dbt1949]

Name the things which generate energy which we cannot detect.

Dark energy?

[Kraken]

As a thought experiment, let's disregard all the unknowns about hypothetical aliens and talk about a human galactic empire, since that's the only one we can ponder with some confidence.

Imagine that humans colonize our solar system in a century or two. Large, self-sustaining populations develop on Mars, the Moon, various gas giant moons, massive space stations, and converted asteroids. Travel between these oases will remain time-consuming and expensive, even with significant propulsion and energy advances, but let's say it's manageable. NASA's already funding a concept that could cut travel time to Mars to just 39 days. One can imagine luxury liners making the Martian run like transatlantic voyages in the Age of Sail. Casual jaunts to the Moon and back might become fairly common. The outer planets are always going to be more of a frontier. It's a long way to Jupiter.

How long would it be before the various populations splinter into distinct societies and, people being people, come into conflict and competition for resources? Tribalism is baked into us; it's not going to wither away on its own. Allegiances and relationships develop and change. One needn't think that they'll resort to war (although one can't rule that out, either, given our long fondness for it). Lower-level conflict and tribal pride are enough to set up rivalries between the populations.

Eventually one of these societies dominates the others and they form a stable federation. Someone finds a practical way to command the incredible energies needed to accelerate mass to near-light speed, and pioneers finally set out for the nearest habitable planet. Right now, the closest one that we have our eye on is 12 LY away, so let's start there. After traveling for 12 years colonists reach the new world. Several decades have passed on Earth thanks to time dilation. Round-trip communication takes 24 years.

You think colonizing the solar system divided people? The new extrasolar colony is completely on its own. But the endeavor succeeded, so more pioneers head for other stars that are even further away. Eventually humans populate half a dozen worlds within 50 LY of home. How long do you suppose it will be before these isolated populations diverge not only socially, but physically? The new environments are more-or-less earthlike, but they're still novel environments with isolated populations. The splinter populations will adapt to them, and eventually it's a stretch to call them "human." Yes, the colonists can control genetic drift if they want to...but would they suppress advantageous mutations just to preserve their ancestral gene pool? Aren't they more likely to encourage physical adaptations to their new homes?

A species that spreads among the stars is not going to remain one species. Maybe the Great Filter is evolution -- the population de-coheres, physically and socially, as it spreads. Fledgling colonies would require time to build the population and industry required to send out their own colonies. And why are they even motivated to do that, at least in the short term? It could take centuries or longer before population pressure or plain old wanderlust gives them the urge to spread further -- odds are that they'll be quite busy for a very long time taming their new star system. By the time second- and third-generation colonies are established, we aren't going to look like earthlings anymore.

Given enough time one of our descendent populations might spread far and wide, but I think the odds are that they'll fizzle out first.

[Daehawk]

Also consider that one day out of the blue either....

1. Someone somehow someway discovers a way to circumvent light speed

or

2.We do venture into our solar system and discover some kind of alien tech that gives us FTL.

Maybe Im a dumb science pleb but I dont agree with the super smart scientist when it comes to travel speed. I think ftl is possible. No clue how but I dont think there are any limits. I still recall reading how it was once thought the Earth was square, the Earth was the center of the universe, you would die at 70 mph or so, the sound barrier is impossible...yadda yadda. I think all it takes is tech advancement.

[Kraken]

FTL would be a game-changer, as might any other new physics. Dark matter/energy might knock our socks off when we finally understand them. Maybe wormholes are real. But since Einstein proved (mathematically, with subsequent experimental support) that it takes infinite energy to accelerate mass to light speed and that time stops when you reach it, I'm not willing to casually wave the speed limit aside.

I will allow that it might be possible to reach a very high fraction of c, as I did in my story.

[noxiousdog]

I don't agree. Species that conquer their evolutionary trees are going to be predatory. Species that expand beyond their systems are going to be aggressive. They may not be spit slavering aggressive but they are going to be aggressive in terms of civilization and expansion. They may not even recognize us as worth the trouble of courtesy as they grab whatever resource on our planet turns out to be valuable to them. Hopefully it's not our women. It might be white quartz for all we know. Common here but rare everywhere else.

We are infants. Nay, we are fetuses in the Universe.

Why would any elements be rare in the galaxy, but not rare on Earth? It would be far easier to get them from an asteroid. I have a hard time thinking they just couldn't synthesize them anyway.

[noxiousdog]

Name the things which generate energy which we cannot detect.

Dark energy?

And yet, we're pretty sure it exists.

[GreenGoo]

If they are immortal what evolutionary pressures are pushing them to spread?

The fundamental pressure. Reproduction. Being immortal doesn't mean you don't want offspring nor does it mean that the resulting genetic roll of the dice isn't beneficial to the species.

Perhaps. I think an immortal species would feel less biological pressure to procreate. What does offspring mean when you're going to be around for every and all generations forever? "We" don't procreate because we think it's a good idea to create biological diversity, even though it is a good idea. Assuming they had genes, maybe they'd just decide to engineer their genetic diversity. Maybe they'll all be clones of each other. Who knows. Imagine away.

How a species could become immortal I have no idea. Science? Evolution? Magic? I think a species that came into existence immortal would probably not have the same biological drives that shorter lived species. A species that becomes immortal might lose those drives.

[GreenGoo]

If humans gained immortality do you really think they'd stop spreading? I think it would only increase the rate (exponentially in the long run).

Maybe. Depends where we are and how we became immortal. Our entire reason for being seems to be reproduction as a form of genetic immortality. What happens when we don't need to reproduce to obtain genetic immortality? Does the human drive remain? If so, why? It becomes an evolutionary relic at that point.

In any case I certainly don't think having an indefinite lifespan would halt the spread of a civilization. There are plenty of reasons to do so. The collection of resources, knowledge, et cetera. Hell they may just be dicks out looking for a trophy to hang on their wall.

Maybe.

Because it's difficult and cost-prohibitive when weighed against the potential gains, I suppose. Ask the world governments. For the record, we've had six manned moon landings, which isn't too bad when you consider how ridiculously inexperienced we are with space travel.

It's actually pretty terrible in the context of this thread. We made it to the moon. Then we stopped. Hell, we didn't even bother to go back again after we'd been there a few times. We're in a thread talking about colonizing the universe, and the human race has decided that the moon was far enough. We didn't even go that far and stop. We went that far and then retreated back home. That was my point. Will future generations go back? Probably. Maybe. Who's going to pay for it? Not enough people today want to pay for the little bit of space exploration we do do, but somehow as a species we're going to decide to pump untold resources into moving from here to there? Maybe. It's a nice dream. I'm not sure it's realistic. But I wasn't even referring to the economic costs involved (which are immense).

We talk about the scale of space, but we can't be bothered to go farther than our moon, and even that's too far for all practical purposes.

Or maybe some satisfaction will come of it. You know, because it's a fun exercise. And fun is satisfying.

You misunderstand my use of satisfactory, but it is an enjoyable thread.

[TiLT]

There's a huge leap of logic here that most of you seem to be making (including the author of the article). What exactly would these advanced civilizations send out that we would be able to detect? We can barely detect planets in nearby star systems, and only by studying orbital patterns and similar things. How could anyone expect us to be able to detect the presence of an alien race thousands of light years away? We're listening to radio, and as pointed out earlier, radio is extremely ineffective over the distances needed for it to matter. Half the Milky Way's stars could be covered in Dyson Spheres for all we know, and we might just think they're black holes.

Our capability to detect and discover other species is so limited right now as to be almost non-existent. An alien species could be on our doorstep, and we'd be none the wiser.

Unless the aliens make contact on their own (and why would they?), we're essentially blind right now.

This is ridiculous every time I hear it. Newtonian physics isn't going to stop working. Except in the case of some technological singularity that transforms a civilization into energy, there's going to be some form of recognizable signature. You can't hide a civilizations energy signature unless you're in a Dyson sphere, and then there's going to be a hole where the sun should be.

We can only detect planets in nearby systems because they don't give off energy (and yet we still can). If something gives off energy, it's easy to detect even at the edge of the universe.

You're saying we have the technology to detect the energy output of another species on a different planet on any given planet in the galaxy? Really?

Our energy output is insignificant compared to that of the sun. We wouldn't have to hide it, because it's so insignificant as to not matter to sensors available to us at the distances we're talking about here. At least as far as I know. Correct me if I'm wrong.

[GreenGoo]

FTL would be a game-changer, as might any other new physics. Dark matter/energy might knock our socks off when we finally understand them. Maybe wormholes are real. But since Einstein proved (mathematically, with subsequent experimental support) that it takes infinite energy to accelerate mass to light speed and that time stops when you reach it, I'm not willing to casually wave the speed limit aside.

I will allow that it might be possible to reach a very high fraction of c, as I did in my story.

As so many science fiction writers have done, we could dream up any number of ways to circumvent it. If we can alter the rules of our universe, then we can break the math and/or substitute new math. How do you do that? I haven't the foggiest.

We're still working on black holes. It's hard to know what is going on in there when you can't see in. That crap is science fiction and yet we know it's real.

I don't do physics outside of newtonian space, but we already know about enough unknowns that we'll be busy for a very long time. Who knows what unknown unknowns are out there? I do find the Fermi Paradox uncomfortable though.

We can be pretty sure time travel never gets discovered, because we'd already have it. Which is how the Fermi Paradox makes me feel.

I'd also like to say that if we are so different from other intelligent species who came before that we are unable to detect their presence, then that makes us pretty unique in the universe all by itself. If as the paradox implies, there have been a zillion intelligent species and we are unable detect even clues of those species, perhaps we are different enough from those species as to be considered special and unique. Shrug.

[Kraken]

How a species could become immortal I have no idea. Science? Evolution? Magic? I think a species that came into existence immortal would probably not have the same biological drives that shorter lived species. A species that becomes immortal might lose those drives.

There would be no evolution without death. Complex life won't arise without it. That's not to say that death can never be overcome, but if immortality appears spontaneously then that species stops changing, so it's counterproductive to complex life.

[Kraken]

[Daehawk]

Immortality would speed up either extinction or expansion. There only so much room on Earth..if no one ever died then we would be forced into concentrating all efforts to expanding or use up what we have and go extinct. And Im speaking of immortality where you can die from damage but not grow old.

[Jeff V]

I don't agree. Species that conquer their evolutionary trees are going to be predatory. Species that expand beyond their systems are going to be aggressive. They may not be spit slavering aggressive but they are going to be aggressive in terms of civilization and expansion. They may not even recognize us as worth the trouble of courtesy as they grab whatever resource on our planet turns out to be valuable to them. Hopefully it's not our women. It might be white quartz for all we know. Common here but rare everywhere else.

We are infants. Nay, we are fetuses in the Universe.

We could be tasty cattle as far as they're concerned. Wouldn't that suck for us!

[GreenGoo]

Immortality would speed up either extinction or expansion. There only so much room on Earth..if no one ever died then we would be forced into concentrating all efforts to expanding or use up what we have and go extinct. And Im speaking of immortality where you can die from damage but not grow old.

That's certainly one scenario.

[GreenGoo]

How a species could become immortal I have no idea. Science? Evolution? Magic? I think a species that came into existence immortal would probably not have the same biological drives that shorter lived species. A species that becomes immortal might lose those drives.

There would be no evolution without death. Complex life won't arise without it. That's not to say that death can never be overcome, but if immortality appears spontaneously then that species stops changing, so it's counterproductive to complex life.

I don't disagree, but I think it's simply our imaginations failing us at this point, since our reality is so completely dominated by the concept of iterative evolution.

That said, what happens if evolution produces immortality? Or science (which some people would argue is just a part of evolution)? Do we keep pumping out kids? If the change is abrupt, maybe we do. If it's gradual, maybe we lose that drive.

[noxiousdog]

You're saying we have the technology to detect the energy output of another species on a different planet on any given planet in the galaxy? Really?

Our energy output is insignificant compared to that of the sun. We wouldn't have to hide it, because it's so insignificant as to not matter to sensors available to us at the distances we're talking about here. At least as far as I know. Correct me if I'm wrong.

Not any given plant, but if you can aim the telescope correctly and avoid something else drowning it out, yes.

We can detect subatomic particles. We can detect elements in suns. We can detect energy emanating from a planet.

The best example might be brown dwarfs. At only 250-600 degrees C, we can still see them.

[TiLT]

The best example might be brown dwarfs. At only 250-600 degrees C, we can still see them.

I'm sorry, but that's a horrible example. A civilization doesn't output anywhere close to that amount of energy on a planet-scale basis. The extremely limited spots in which we do are so small as to be undetectable at these distances, and even if we could detect them we'd probably be unable to distinguish them from natural radioactive, volcanic or chemical activity.

[Jaymann]

Yeah, unless some civilization put out a high-powered beacon expressly for the purpose of being detected, it is doubtful we could distinguish signs from natural phenomena. But that would be incredibly stupid and reckless.