Why haven’t we been contacted by extraterrestrials?

[Pantastic]

@k9bfriender

Can you use your iphone at the same time as I use it? I think not. In that case, we are going to need to have one for each of us.

How many megatons of iphones is each person going to use at any one time?

The same with all other consumer materials, unless you have an idea of all of us sharing the same materials, or you are assuming that population growth will stop.

I’m asserting that civilizations that can’t control their population growth will inevitably self-destruct, because if they can’t regulate population growth they will inevitably outgrow even the theoretical maximum population a given area can support, and (much sooner) any means of moving new population out of the area. Given that technological civilizations can control their population growth, I don’t think it’s impossible that they will eventually decide to prioritize something other than simple raw growth, and so may have a population that remains steady, grows only slowly, or even shrinks to a level that they like.

“Population growth will stop” is a much stronger assertion, and not one that I’m making or believe. Remember, this thread is about ‘why haven’t we been contacted’.

I really don’t think you are thinking long term about this. I think you are thinking on the order of decades or centuries. This is not a long period of time.

I really don’t think you’re thinking about the scale of resources available just on earth, much less in the entire solar system.

Try thinking on the scales of tens or hundreds of thousands of years to start. Then realize that there is no reason you shouldn’t be thinking on millions, tens of millions, hundreds of millions, and even billions of years.

Intelligent life hasn’t been around for billions of years on Earth, and I haven’t seen evidence that it would be easy for it to arise faster on Earth. You can’t get a whole lot older than earth without leaving the Population I stars, but non-population I stars lack heavy (that is, not H and He) elements and are likely not to support life.

So I think we’re only looking at most something in the ‘hundreds of thousands’ to ‘tens millions’ of years for intelligent life to have spread, not ‘billions’. Remember, the thread is about ‘why haven’t we been contacted by extra terrestrials’, not ‘what might happen in a billion years time’.

Now, yes, humans are involved in these steps, at the moment, as computers have not advanced enough to not need the occasional judgement of a human, but that involvement is decreasing. As computer technology progresses, and they become better and smarter, humans will be more and more cut out of the loop, until we are essentially only making decisions based on our preferences and needs, not based on the best way to extract, refine and process materials.

I don’t believe the claim implicit to this idea that you can create software capable of human-level or better decision making on broad and open-ended questions (like you would need for setting up mining and factory replication operations in an unknown, distant solar system) that also is completely subservient to whatever initial goals humans give it, never evolves to have its own goals or objectives, never breaks down and has no risk of going out of control and destroying the home system over millennial time scales (much less the billion year time scales you’re talking about).

The idea of self-replicating machines that you can fling at another solar system, and they will figure out how to harvest it, send you back materials, and send more ‘starter sets’ to other stars that are smart enough to handle all of the problems that come up and make all decisions needed, but also won’t ever have objectives of their own even after billions of years of operation including significant radiation exposure is magic. Pointing to ‘but look, we have automated mining equipment, the rest is just engineering problems’ is mere handwaving.

[levdrakon]

@Tibby or Not Tibby

So, at best, we have only galaxies within our Local Supercluster with which we could possibly make contact. This certainly includes a plethora of star systems that could (and I believe do) sustain life, but life that can contact us? I doubt it. It’s a matter of odds.

If no civilization within the Milky Way has developed interstellar travel/communication, we won’t make contact with them. I think the odds are good that no civilization within our galaxy can travel between stars.

If a civilization in a galaxy beyond the Milky Way has developed interstellar, but not intergalactic travel/communication, we won’t make contact with them either. I think the odds are good that no civilization within our Local Group can travel between galaxies.

We’re actually closer to the nearest dwarf galaxy than the center of our own galaxy. Space seems to be pretty messy with stars and planets and I have a feeling a civilization or colony or replicating probe could hop & skip all the way to another galaxy if it really wanted to. Not sure why they would but it’s difficult to guess alien motivations.

The universe was smaller and more dangerous 5 billion years ago until supernovae and gamma ray bursts calmed down and became less frequent. It’s taken most of that 5 billion years to develop humans. Maybe we are one of the first ones, and the number of habitable planets now, is nothing compared to the number of habitable planets there will eventually be.

Maybe we don’t become an interstellar species, but someone else eventually will. We should leave some big, obvious things behind for them to find and let them know we were here.

[Tibby]

@levdrakon

<snip>
Maybe we don’t become an interstellar species, but someone else eventually will. We should leave some big, obvious things behind for them to find and let them know we were here.

I agree, leaving something for some alien intelligence to find could be a good thing (or, it could be an incredibly bad thing). But, what would you leave that would be identifiable and likely to be found lets say thousands or millions of years into the future?

[Mijin]

@kanicbird

Watch Star Trek and learn about the prime directive. Consider its wisdom.

Considered it…it doesn’t make sense. And the series is completely inconsistent in how it’s applied.

In short it is the same reason why we would rather not interfere with the natural habits of animals, or for that matter the few primitive human tribes that still exist.

If a human from a primitive tribe wanted to know about modern medicine, we’d tell her. Our non-interference thing is nothing like the prime directive.

[marshmallow]

@Tibby or Not Tibby

But, what would you leave that would be identifiable and likely to be found lets say thousands or millions of years into the future?

Etch a giant smiley face on every geologically dead moon.

In Nemo Ramjet’s All Tomorrows, the alien Qu dot every planet they visit with pyramids that are several kilometers tall. I imagine those would last quite awhile in places without an atmosphere.

[efyou]

I’ve always felt since a little kid that we are basically in somebodies fish tank. Aliens, a God etc.

We’ll meet them when they are done playing with the fish tank. Probably dump us right out on the grass in their back yard. Heh.

[eburacum45]

@Pantastic

The idea of self-replicating machines that you can fling at another solar system, and they will figure out how to harvest it, send you back materials, and send more ‘starter sets’ to other stars that are smart enough to handle all of the problems that come up and make all decisions needed, but also won’t ever have objectives of their own even after billions of years of operation including significant radiation exposure is magic.

Nevertheless, we could probably develop such sophisticated machines within the next few hundred years, assuming our civilisation continues to develop in complexity; within a thousand years such complex and competent devices would almost certainly be feasible. A thousand years is a very short time compared to the history of the universe.

If you really want them to be free from replication errors, you could make them fail-safe and self-correcting in a way that doesn’t occur in nature; if they deviate a small amount from the expected parameters that deviation is corrected, if they deviate too much, then they shut down. A multiply-redundant database could prevent any errors on a timescale comfortably exceeding the age of the universe.

Replicators of this nature do not exist in nature, and in my opinion they could be very dangerous - more dangerous perhaps than replicators that can evolve, because they can’t be dissuaded from their pre-programmed course of action, and you risk a paperclip catastrophe. Any civilisation that created such a single-minded swarm would be very foolish indeed.

But make the replicators just a little smarter- for instance, if they can communicate with some central control, using suitably secure encryption, then they could have their goals changed if and when necessary. A replicator swarm that covers an entire galaxy would require a minimum of 100,000 years to be reprogrammed - but once again, this is a small period of time compared to the age of the Universe.

[eburacum45]

@Pantastic

Intelligent life hasn’t been around for billions of years on Earth, and I haven’t seen evidence that it would be easy for it to arise faster on Earth. You can’t get a whole lot older than earth without leaving the Population I stars, but non-population I stars lack heavy (that is, not H and He) elements and are likely not to support life.

So I think we’re only looking at most something in the ‘hundreds of thousands’ to ‘tens millions’ of years for intelligent life to have spread, not ‘billions’. Remember, the thread is about ‘why haven’t we been contacted by extra terrestrials’, not ‘what might happen in a billion years time’.

This is not necessarily correct. Many Population 1 stars are at least a billion years older than the Sun, and there are almost certainly worlds similar to Earth that are at least a billion years older than our world. Add to that the fact that stars with lower metallicity often have fewer and smaller gas giants, but can still have a significant number of small, rocky worlds, and you have the potential for life-bearing worlds many billions of years older than Earth.

Of course there is a non-zero chance that there are no other life-bearing worlds in the galaxy, or the universe - but if there are, we cannot yet constrain their ages with any confidence.

[Mangetout]

@Mijin

Considered it…it doesn’t make sense. And the series is completely inconsistent in how it’s applied.

Yeah, it’s more like the Prime Suggestion.

[mlees]

@Trinopus

Seriously, the same way the Huguenots got to England. If the ships exist, they’ll find a way to get passage. Religious freedom has been behind many migrations here on earth. If interstellar passage is possible at all, this could become one of its purposes.

A frontier implies frontiersmen.

Forced resettlement (to prison colonies, or to take slaves) is another reason that, historically, seems to be behind significant population transfers.

[PatrickLondon]

A frontier implies frontiersmen.

Only when it’s a frontier between an organised state and a supposed wilderness. A frontier between states at roughly the same levels of organisation is a rather different matter.

And it would be more likely that in a contact between us and extra-terrestrials, they’d see us not as frontiersmen, but the savages.

[Vinum_Lupum]

@k9bfriender

… or you are assuming that population growth will stop.

It will. Inevitably.

Contrary to popular belief, populations (or anything else in the real world, for that matter) never grow exponentially. They always follow a ‘logistic function’. When a necessary resource for the growth starts becoming scarce, growth inevitably slows, and eventually stops.
Always.

As some wise-ass whom I can’t remember once said, “If a trend can’t continue, it won’t”.

@k9bfriender

…And, as far as re-using them, well, there is some level of waste that is likely in every recycling cycle, so new materials will be needed to make up for this.

Unless the ‘waste’ is winding up in a black hole, all it takes to recover and reuse it is energy. Atoms don’t cease to exist (except for the ‘black hole’ exception). Energy is the only limiting factor for recycling. ‘Running out of resources’ as you postulate is impossible. Only running out of the energy to recover and recycle the materials limits the process.

@k9bfriender

…
I really don’t think you are thinking long term about this. I think you are thinking on the order of decades or centuries. This is not a long period of time.

Try thinking on the scales of tens or hundreds of thousands of years to start. Then realize that there is no reason you shouldn’t be thinking on millions, tens of millions, hundreds of millions, and even billions of years.

On those timescales, energy, alone, is the only limit. No one can run out of material resources within their own solar system. They only run out of the ‘solar’ part.

@k9bfriender

…
Do you realize that no matter our recycling efforts, the sun is gonna run out in just a few short billion years?

Actually, we run out in only 500 million (give or take a few hundred). The Sun runs out in about 4 billion. Life on Earth runs out when the Sun gets a bit hotter, and fries our [del]asses[/del] planet a lot sooner.

I could go on, but I’ve had enough dealing with your demonstrably wrong crap.
Oh, wait. There’s also this stupidity:

@k9bfriender

…
Do you not get that technology progresses? That we get better at doing things, we make better machines? Do you think that we will just suddenly stop the technological progress we have been doing the last couple hundred years?

Technology also necessarily must follow that same logistic function. It’s going to hit it’s limit of growth. We’re not near it now, but we’re going to hit it. Inevitably.

Your belief in future magic is touching, but it ain’t gonna actually happen. Because it can’t.

[Defensive_Indifference]

@Stranger_On_A_Train

No, I don’t believe I’m going to do that. Between the permissiveness toward cunt-ass trolls and blatant defamation to the smash-cut modal window ads and the frequent redirect to scammy malware sites, I’m done with this board.

Stranger

I know I’m a day late, but I hope you’ll see this. Please stick around. You add more to the SDMB than probably any other poster here. Not that my opinion counts for much, but you’re one of only a few posters whose contributions I actively hope for and seek out.

[up_the_junction]

Would you deal with Donald Trump if you didn’t have to?

True story.

[Vinum_Lupum]

@up_the_junction

Would you deal with Donald Trump if you didn’t have to?

True story.

Duhh, whut?

[Fuji]

By coincidence, I just happened to read an interesting article (PDF) by Nick Bostrom last night that directly addresses this very question.

Originally Posted by Nick Bostrom

*"We have every reason to believe that the observable universe contains vast numbers of solar systems, including many that have planets that are Earth‐like at least in the sense of having a mass and temperature similar to those of our own orb. We also know that many of these solar systems are much older than ours. From these two facts it follows that there exists a “Great Filter”.

The Great Filter can be thought of as a probability barrier. It consists of one or more highly improbable evolutionary transitions or steps whose occurrence is required in order for an Earth‐like planet to produce an intelligent civilization of a type that would be visible to us with our current observation technology. You start with billions and billions of potential germination points for life, and you end up with a sum total of zero extraterrestrial civilizations that we can observe. The Great Filter must therefore be powerful enough— which is to say, the critical steps must be improbable enough— that even with many billions rolls of the dice, one ends up with nothing: no aliens, no spacecraft, no signals, at least none that we can detect in our neck of the woods."*

(Bostrom was previously referred to in this thread in eburacum45’s Post #107. I also join the others in hoping that Stranger On A Train reconsiders his decision to leave the board, as I find his contributions here to be considerable, FWIW.)

[Fuji]

@Vinum_Lupum

Technology also necessarily must follow that same logistic function. It’s going to hit it’s limit of growth. We’re not near it now, but we’re going to hit it. Inevitably.

Your belief in future magic is touching, but it ain’t gonna actually happen. Because it can’t.

:dubious: Cite, please?

[Vinum_Lupum]

@Fuji

:dubious: Cite, please?

Cite for what? That everything necessarily must hit a limit? I would have thought that that was obvious.

[k9bfriender]

@Vinum_Lupum

It will. Inevitably.

Contrary to popular belief, populations (or anything else in the real world, for that matter) never grow exponentially. They always follow a ‘logistic function’. When a necessary resource for the growth starts becoming scarce, growth inevitably slows, and eventually stops.
Always.

Yep. That’s why we would need to get more resources, to continue to grow our population.

It is a ridiculous argument that we would not get more resources to grow our population because our population is not growing because we are out of resources.

You cite talks about resource limited growth, like on an island or a petri dish. I am talking about getting rid of that limit by looking outside the petri dish.

As some wise-ass whom I can’t remember once said, “If a trend can’t continue, it won’t”.

Just FYI, Herbert Stein

Unless the ‘waste’ is winding up in a black hole, all it takes to recover and reuse it is energy. Atoms don’t cease to exist (except for the ‘black hole’ exception). Energy is the only limiting factor for recycling. ‘Running out of resources’ as you postulate is impossible. Only running out of the energy to recover and recycle the materials limits the process.

Now who is imagining technology? You assume a 100% efficiency recycling program, but discount any of the other progress that I predict.

You don’t think that some metal vapors from recycling will drift off and become interplanetary and eventually interstellar dust? You think we will capture every single atom used? Obviously, organics and volatiles will be even harder to trap, contain, and re-use.

You also seem to have not heard of radioactive materials, as you seem to think that the only time that an atom is no longer available is if it goes into a black hole.

On those timescales, energy, alone, is the only limit. No one can run out of material resources within their own solar system. They only run out of the ‘solar’ part.
Actually, we run out in only 500 million (give or take a few hundred). The Sun runs out in about 4 billion. Life on Earth runs out when the Sun gets a bit hotter, and fries our [del]asses[/del] planet a lot sooner.

How does that in any way contradict what I said. I had even considered responding to Pan about that point that the sun would be getting hotter, and that was another reason to expand our spheres of influence, but as he was struggling already, figured that’d go over his head.

Nice catch of yours, but very misguided on your attempts at insults.

If I had said anything along the lines of “we only have a few billion years on this planet.” you may have a point. As that is not what I said, you are just making your posts look foolish.

I could go on, but I’ve had enough dealing with your demonstrably wrong crap.
Oh, wait. There’s also this stupidity:

Your insults would be more biting if they were in any way shape or form accurate. Instead your insults just highlight the ignorance of your own posts.

Technology also necessarily must follow that same logistic function. It’s going to hit it’s limit of growth. We’re not near it now, but we’re going to hit it. Inevitably.

Now, that there is utter bullshit. What is the “logistic function” to technological growth? We’ll stop advancing when we hit up against the laws of physics as we know them, but there is no such thing as limiting technology based on resources. In fact technology is pretty much by definition the ability to get more out of a given set of resources, so I don’t know where you got that line.

Your belief in future magic is touching, but it ain’t gonna actually happen. Because it can’t.

As you are on record as saying that we will have 100% efficient recycling, with no losses whatsoever, I am not sure I am the one who is looking to future magic tech.

What is the limiting factor do you think, in my timeline of future technology?

Is it that we can’t get into space?

Is it that we can’t get to the asteroids?

Is it that we cannot mine those asteroids?

Is it that we cannot mine those asteroids autonomously?

Is it that we cannot have manufacturing on asteroids?

Is it that we cannot have autonomous manufacturing on asteroids?

Is it that we cannot have computers that are capable of functioning independently?

What is the “logistic function” that you believe will limit technological development?

[Darren_Garrison]

@Vinum_Lupum

When a necessary resource for the growth starts becoming scarce, growth inevitably slows, and eventually stops.

Or they will overproduce so that there are too many for the resources, many will die off leaving room for expansion, which overstresses the resources, which leads to many dying off, which leads to…all in a sort of rabbity-foxy way.