Why We Haven't Met Aliens Yet

[Roboramma]

That seems like an awful lot of work when compared to just building something that can move fast, scan and map incoming objects and plot avoidance trajectories. Though that sounds really hard, using comets as space vehicles sounds wayyy harder.

I don't think you understand: the comets aren't primarily space vehicles. They are primarily colonies in their own right.

 

[BravesFan]

Still seems like an awful lot of work to me .

 

[Corsair 115]

Again, the proposition is not that they are living on a planet orbiting some far off star and then decide to come to the earth. The proposition is this: on some distant planet life began. Over time, intelligent life evolved. Over a little more time it developed a techological civilization. Over some more time it's technology progressed to the point at which it was capable of interstellar travel. By this time, or perhaps after considerably more time, it had already tapped the resources of it's home system to the point that it made sense to go elsewhere.

Some sort of interstellar craft was launched to that other star which was capable of beginning the development of that system that would, over time, put it on the course to attain a level of development similar to that of the previous system.
Wash, rinse, repeat.

Now, if this happened, it's unlikely that the first steps happened exactly as they did on earth: ie, if we aren't the first technological civilization, whatever other such civilizations there are would have come about much earlier than us.
The later steps are faster than the earlier steps: that is, once you've got an intelligent species (biologically similar to us in it's capacity to develop a technological civilization), it shouldn't take more than several millions of years for such civilization to get underway.
Once such is underway, it shouldn't take more than tens of thousands of years for it to reach our current level of development.
Once it has reached this level, if interstellar travel is possible it shouldn't take more than thousands of years to get there.
Once they have gotten to another star, developing it shouldn't take more than thousands of years, because all the technological innovations have already been made.
Thus, you get an expanding sphere of colonization moving outward from the home star at some fraction of c.

Why hasn't that sphere reached earth yet? It's not good to say "they can use the resources near home" they've already used them all.

The simplest answer: there isn't anyone else around in this galaxy except us. Or at least, there isn't anyone else around in this galaxy as technologically advanced as your proposition requires. Maybe the folks with the kind of technological level you're talking about are over in M31, and even with their tremendously advanced technology they still cannot bridge the mind-boggling huge intergalactic distances.

 

[Roboramma]

I agree Corsair. There are plenty of other possible resolutions of the paradox, but I find that the simplest as well.

Logic, what exactly "seems like a lot of work"? Note that the colonizing of the solar system is not posited to be for the sake of interstellar travel, but simply done for it's own sake, as a natural outgrowth of the development of the technology that will make it economically feasible.
Once that has happened, if another star happens to drift relatively close by, competition for resources within this solar system (sunlight being one, but there are plenty of things that could become scarce for some people within such a civilization) could lead to the inhabitants of some worldlets choosing to move to that other star.

 

[Donn]

I too have this sad suspicion that the galaxy is devoid of others like us.

I see little movies in my mind, of people rising from the muck; building towards freedom from scarcity and tyranny. I see them falling-short; climate fail, war, disease, their Sun 'blipping' enough to fry them, comets and meteor strikes, to list only what I can.

I heard someone once describe this as little flashes of light. Look up at night. In all the last billion years, how many flashes of light have burned, rising from nothing to bright white and then puffing out? Pfft. Here. Pfft. There. Little pauses in between. Pfft.

Kinda makes me want to engrave all our art and knowledge onto something tough and shoot it out and away. To make this hard human story all worthwhile, before...

Pfft.

 

[Hellbound]

Well, to be fair, it ma not be devoid. We've explored very little beyond our solar system, and even reaching the edges of it brouhgt about some suprising findings.

It's equally possible that, at our technological and scientific level, we're simply under-estimating the difficulty and cost of interstellar travel. It could be that things that seem feasible to us now with just a bit more technology will turn out to be more costly and complicated than we think (for example, fusion is still 20 years away, and has been for at least that long). There may be medical, psychological, or physical difficulties we haven't discovered yet.

Assuming this is true, and there is some sort of barrier that makes interstellar travel unfeasible for some reason, then there could well be other advanced civilizations not that far away from us.

 

[Donn]

True. Make that, devoid of aliens that sci-fi travel about.

 

[JudeBrando]

"Chuck Missler - Return Of The Nephilim, UFO's, Aliens & the Bible"

"Throughout ancient history, there has been records of half man, half god creatures (demigods) which we dismiss as myths. In ancient Babylon, they talk of the Annunaki. 'Gods' that came down from the heavens and taught man technology and knowledge. These 'gods' procreated with women and produced : Children of gods. Are these children/Nephilims returning? Are these fallen angels returning? Who built the pyramids? Who built the Temple of BaalBeck in Lebanon?"

 

[epepke]

Aliens are shy. They dial eight numbers on the Heechee drive and can't bring themselves to dial the ninth.

 

[Donn]

That's not shy, that's sane! Them Heechee ships are scary.

 

[jnelso99]

We are not detectable by radio wave unless you happen to be in our VERY short neighborhood, at worst 1 light year (more like much less than that). The reason is extremely simple : the signal energy is fix, but with the distance the wave front increase significantly (in d^2) making the energy of the signal drop rapidely, and for all signal sent on earth which were radio or TV, a quick calculation shows they did not get very far until they are so low as to be virtually undetectable above interstellar noise level for those frequencies.

I like this illustration:

Wikipedia has this artist's conception of the Milky Way galaxy. It's a 5600 x 5600 pixel image. Assuming we've been sending out radio signals for 100 years (nice round ballpark), our radio signature (assuming full power, no signal drop, ideal) on that image would be a circle with a diameter of about 8 pixels. Less given Aepervius' notes. Easy to miss.

 

[Dinwar]

"Throughout ancient history, there has been records of half man, half god creatures (demigods) which we dismiss as myths. In ancient Babylon, they talk of the Annunaki. 'Gods' that came down from the heavens and taught man technology and knowledge. These 'gods' procreated with women and produced : Children of gods. Are these children/Nephilims returning? Are these fallen angels returning? Who built the pyramids? Who built the Temple of BaalBeck in Lebanon?"

You have a better chance of procreating with a sea slug or bacteria than you do with an alien. At least your genetic code shares SOME similarities.

Well, to be fair, it ma not be devoid.

Humans have been going into space for what, sixty years? Seventy? Not a century yet, that's for sure. The galaxy could be TEAMING with life like our own--life that's just getting started with this whole space exploration thing. Given how fast life arose on the Earth (4.6 billion year old planet, life arose 3.8-3.9 billion years ago) it's entirely likely that there are huge numbers of planets with simpler life on them.

 

[ceptimus]

Say, in a thousand years time, we develop the technology to build a ship that can travel to nearby stars in a few hundred years.

Now, would we bother to build such a ship? Chances are that it wouldn't be the first ship to reach the nearby stars: fifty years after it had launched we would expect to have built a faster design that would easily overtake it and win the race. Of course, the same argument applies to the new faster ship. So it's difficult to see how we'll ever get started.

Two reasons we might get started:

1. If there's a clear technological speed limit - we consider that say 0.01 c is obtainable but that no foreseeable technology will ever allow us to go faster.

2. There's some destination that can be reached in just a few years with existing technology. Unfortunately, as far as we know, there are no intermediate destinations - there is the Solar System, just on our doorstop, and then a huge gulf to the nearest stars.

 

[gnome]

I would say there's probably a biological limit to how many g's of acceleration a human body could survive, even if it were in some kind of hibernation. As for an intermediate destination, the Oort Cloud has some nice resources about 1 light year out, which is as much as about 1/4 of the way to the nearest star.

 

[ceptimus]

You don't need many g, providing you can keep applying it for long enough. If we use Newton's laws then a steady 'one gee' gets us up to light speed in just under a year!

 

[WhatRoughBeast]

You don't need many g, providing you can keep applying it for long enough. If we use Newton's laws then a steady 'one gee' gets us up to light speed in just under a year!

And if we use Einstein's laws we get up to just under light speed.

 

[Donn]

Chances are that it wouldn't be the first ship to reach the nearby stars: fifty years after it had launched we would expect to have built a faster design that would easily overtake it and win the race. Of course, the same argument applies to the new faster ship. So it's difficult to see how we'll ever get started.

(Visions of time-dilated people chasing one another in the future and the past. Too weird.)

I'd say one good reason would be to wave and gesticulate (and those teenagers on deck B, you just know, are gonna moon 'em) at the old ship you are overtaking. Leave a cloud of streamers in your wake.

 

[Corsair 115]

You don't need many g, providing you can keep applying it for long enough. If we use Newton's laws then a steady 'one gee' gets us up to light speed in just under a year!

The problem is that you then need a steady supply of fuel for the entirety of that almost-a-year. And you'll need another almost-a-year's worth of fuel supply to decelerate as you approach your destination.

That's a lot of fuel.

(And that's not even touching upon the issue of an engine that can operate non-stop for almost a year without needing any kind of maintenance or repairs.)

 

[Democracy Simulator]

I've been thinking about this topic a lot recently and I'm glad to see it pop up on the forum.

My guess is that superhuman/alien artificial intelligence and seamless virtual reality/consciousness uploading are much more easily attainable and desirable for the curious technological civilization, than is interstellar travel. Once 'the singularity' happens, for some reason(s), that virtual civilization does not feel it necessary to investigate the 'real world'. Perhaps, lacking any real motivation for continuing existence, they switch themselves off; perhaps they find better things to do than real life; perhaps it is more fun to be a God of a virtual universe than to investigate the real one (and perhaps the superhuman intelligence factor makes such investigation redundant).

So, for every civilization there would be a brief period between the invention of the computer and the cessation of real life. Perhaps 100 years or so, which may explain the lack of signals.

 

[Donn]

Pfft!