Intelligent life in the galaxy

Great Debates
1

I have reached a tentative conclusion that we are probably the only intelligent life form in our galaxy and possibly in the universe. I base this conclusion on the following facts:

  1. The Universe is about 15 billion years old and the Milky Way galaxy is not much younger. The oldest stars are almost as old.

2.Some of the giant stars which formed early in the history of the galaxy would have exhausted their fuel in a few million years, gone nova, and spewed their contents, including newly synthesized heavy elements into the interstellar medium. These elements would have been available to be incorporated into later stellar systems which could have included rocky planets like the earth.

3, The sun is only about 5 billion years old. Therefore it is probably a third generation star. If intelligent life is a normal development, there should be many civilizations which are many billions of years old.

  1. Such beings, even if they arose only around one star, would have colonized the galaxy by now. Consider that, on a cosmic scale, we evolved only yesterday and we developed machines and rudimentary computers only a couple of seconds ago. Even so, we can certainly project, estimating very conservatively, that we will thoroughly explore the whole solar system and set sail for the nearest stars within a thousand years. Even if we were never able to travel faster than 10% of the speed of light, we could explore the galaxy in much less than a million years. But other hypothetical beings, some of whom should have been around for billions of years, as far as we can tell, have not. And we should see the evidence. The galaxy should be awash in artificially generated electromagnetic radiation. It shouldn’t be all that difficult to detect. And, as Enrico Fermi said, “Where are they?”

Let the debate begin!

The philosophers have only interpreted the world in various ways; the point, however, is to change it. (Karl Marx, 1845)

2

I think the lack of any artificial EM radiation is the most telling point in your favor. The lack of galactic wide colonization is possibly explainable. Look at how the Chinese turned inward after some spectacular exploratory voyages to South Asia Africa and most likely the west coast of North America. Look at how the US after a brief flurry of space exploration turned away from it. (Whoops, that is from one of my future history texts, please ignore.) Maybe the exploratory urge gets buried in large cosmopolitan, technologic cultures. Maybe once you make a Dyson Sphere (?), you don’t need to go anywhere else. And maybe they are out there right now, watching us ala Contact or Art Bell. The 10 dimensional Multiverse is just too big to waste on only us.

3

Your items 1 and 2 are facts. The first part of your item 3 is a fact and the second part is an assumption, for which you have provided no support. Your item 4 is a supposition, for which you have provided some argument.

I dunno whether or not we are the only intelligent life. I’m not always sure we’re intelligent {grin}. I would like there to be other intelligent life, and I kind of think ther is, but I don’t have a good argument one way or the other.

jrf

4

Certainly by now we would have picked up radio signals, if other advanced civilizations existed (or did exist). Of course, it is entirely possible that our species is the only one that has enough curiosity to go looking for neighbors. What I have always wondered is, if in the event we do hear signals from the void, what will the fundies say 9they will probably blame them on Satan, demons, or both).

5

[Sarcasm]There is no intelligent life in this galaxy whatsoever. For proof, just see the Pit.[/Sarcasm]

One quick point with reference to the OP:

Much of life as we knows it depends on the present ratio of elements, all but two of which are derived from those early supernovae. So it may be likely that no life can evolve until the carbon, nitrogen, calcium, iron level of the planet it evolves on is at a certain level, and therefore there is no life that significantly (over a billion years) predates our own planet’s. Sobering thought: We may be the Elder Race of the galaxy.

It is only within the last 150 years that any serious suggestion of going to other planets has been advanced by even the wildest dreamers. All but a few of the youngest of us have known people who were alive before man knew how to fly. The older among us can remember when we could not leave the planet for space, even briefly.

Even if we assume another race on another planet achieved intelligence shortly before us, what is to say that it moved at our pace to the Space Age? Or went that intellectual direction at all? And supposing it did, how long would it take to expand from the other side of the galaxy to here? Argument 4 is reasonable but makes way too many assumptions about what an intelligent race will do and at what pace.

6

If there was an intelligent civilization even as close as a planet of Alpha Centauri, we wouldn’t be able to pick up their radio transmissions unless they were beaming a signal right at us.

Our own signals wouldn’t be intelligible (or distinguishable from noise) outside our solar system. Oh, and the volume of our radio transmissions have taken a dramatic leap downward over the past decade or so, what with cable TV and satellites.

SETI is a nice idea (and cheap, too), but it does presuppose that out there is some University of the Air that’s broadcasting Important Stuff Right To Us.

I just finished reading Joel Achenbach’s Captured by Aliens, a good investigation of extraterrestrial intelligence for the layman. I’m with Stephen Jay Gould on this one: there’s no evidence either way. There’s no way at all to know whether there are or aren’t intelligent civilizations out there.

…but when you get blue, and you’ve lost all your dreams, there’s nothing like a campfire and a can of beans!

7

Life as we know it is limited to a carbon base. It is true that there is no evidence for life based on other elements, but the concept is both feasible and probable. Assume for a moment that there is silicon based life. Due to the bonding nature of silicon, the attributes we deem necessary for life (respiration, reproduction, etc.) would be incredibly slow (relative to a carbon base) unless some type of catalyst were to be an innate part of “their” chemical make-up. In light of this possibility, life could have originated a very long time ago. Translational motion would be extremely slow, perhaps nonexistent, and therefore expansion outward from the planet of origin might be greatly inhibited.

…just a thought…

8

And how do you define “intelligent life”? Neanderthal man used tools so they showed intelligence, but if they had become the dominant intelligent species, they may never have gotten as far as we have.

There are simply too many variables to say definitively that there is not other intelligent life out there. My personal opinion is that there is

“The large print givith, and the small print taketh away.”
Tom Waites, “Step Right Up”

9

Our local paper just reviewed a book by a couple of scientists that believe life is probably very common, but intelligent life would be fantastically rare, so rare that we may be the only example.

They pointed out that for intelligent life like humans to evolve requires a fantastic chain of coincidences. The star has to be about the sun’s size, can’t be variable, and has to have survived as long. The star can’t be in a crowded part of the galaxy where there is lots of radiation and stuff to smash into. The Earth benefitted from having the Jovian planets to act as meteor blankets. The presence of a large moon gave the Earth tides which helped move things around and stimulate diversity. The earth’s tilted axis moderates temperatures. The right composition of elements was available. We never suffered a devastating meteor impact during the 4 billion years it took for life to evolve from green sludge to complex animals. And the list goes on.

I find the lack of radio signals in the universe to be troubling. From how many light-years away could Aricebo pick up a signal of say, 10 KW? Something like our powerful TV broadcasts? If the answer is “from across the galaxy”, then it seems to me that we have a big problem. But if the answer is only a few hundred light-years, than maybe we’re just in a desolate outpost.

10

Nen, no argument about silicon-based life as a possibility. But silicon is even further up the binding energy curve than carbon, and just reinforces my point. What I was doing, BTW, was not saying life based on carbon (ours), silicon, sulfur, iron, etc., but noting off elements important to present living things’ metabolism, which were “cooked up” in hot stars that became supernovae.

Unless you want to argue for hydrogen- or helium-based life, you need to wait for a bunch of supernovae to go off to provide a reasonable stock of heavy elements. Chuck, any SF speculation relative to this?

11

The answer is “about the orbit of Pluto.” At the moment, all we’ve proved conculsively is that Wells’ Martians aren’t gonna get us.

…but when you get blue, and you’ve lost all your dreams, there’s nothing like a campfire and a can of beans!

12

The Universe may well be teeming with life, but there’s no reason to think that intelligence is common. Our own history proves it.

Intelligence arose here only once, and that was yesterday, geologically speaking. And it may have never happened if a huge comet hadn’t struck earth 65 million years ago.

Steven Jay Gould says that even with the impact, if the whole thing was replayed, we wouldn’t be here. And it doesn’t follow that some other species would win the lottery and develop intelligence.

There are millions of species here, and they get along just fine without technology.

And then there is the size ratio of the Moon and Earth, which is the largest in the solar system. In fact, it can be thought of as a double planet system. This may be a very rare circumstance.

I mention it because the Moon’s gravity creates high tides, which must have put pressure on stranded organisms to colonoze the land. Water dwelling organisms, regardless of intelligence, could never develop a technical civilization.

And Fermi’s question is profound. Where are they? We have made our presence known to anyone within a 100 light year radius with our radio signals. If they’re listening, they know we’re here.

We’re listening, too. So far, zilch.

13

I think this is the weak link in the argument. Such beings would still be bound by the laws of physics, so no faster-than-light travel. There is no particular reason to suppose that they would be blessed with spectacular longevity (not to mention high boredom thresholds).

That means that, basically, colonising the galaxy would involve building spacecraft capable of supporting life in deep space for more than one generation, and packing off a group of astronauts to breed in space, never to be seen again. Why would they bother?

14

Yes, I know how to spell colonize.

There’s something wrong with my keyboard. Yeah, that’s it.

15

Da Ace - What are you talking about? Our deep-space tracking system could pick out a 3-watt signal from Pluto. When I was in engineering I designed a communications system for a Saturn probe as my final project, and the amount of power you need to be detected is pretty small. The bitrate of the signal is proportional to the power, so you couldn’t send information very quickly on a low-power carrier, but we could detect it.

I can dig out my textbooks and do the math on this stuff, but I figure there are better anwers already out there. Like, if we assume that another civilization went through a phase where they were sending high-density data like TV or computer network connections via broadcast, we can figure how much power they probably used, and how far away we could detect it. The answer is certainly many light-years, but just how far?

What I’m getting at is that once a civilization passes this point and starts communicating between planets and stars they almost certainly will used beam-directed communications like lasers and microwaves, which we couldn’t detect.

How long do you think it will take us before we stop relying on broadcast radio transmissions of significant power? Within our lifetimes we could see almost the complete elimination of any broadcast services. Our planet will become pretty quiet in terms of radio energy emitted.

16

Polycarp has a good point. We must struggle not todraw conclusions about the course of evolution of alien based on the sigle data point of our own planet. However we may consider the approximate amount of time it takes for heavy elements (i.e. heavier than hydrogen and helium) to appear and coalesce into planets as a property of the universe as a whole. Given that, and the approximate age of the universe, earth-type life has had the opportunity to appear only fairly recently.

Still, life doesn’t necessarily appear in series on different planets; thousands or millions of planets could be hosting the development of life concurrent with our own. A difference of only a million years - small on the galactic scale, or even the scale of geological/biological history - is an enormous amount of time for the development of culture in an intelligent species. So the notion of species not TOO much older than we that are nevertheless significantly more advanced is not crazy.

[As an aside at this point, I would ask you to consider the following proposition: No matter how intelligent and advanced a species becomes, they will never be able to build a perpetual motion machine. The universe does not support such a device. Agreed? I’ll come back to this in a minute.]

WRT the OP. I think you overstate the case a little, but I’m inclined to agree that intelligent life may be quite rare. Consider that there are a huge number of stars in the galaxy, but the vast, vast majority of them are concentrated toward the galactic center, far too close together to support life as we know it (LAWKI). Too much radiation, physical collisions, rapidly changing environments, etc. There will be some band around the center of the galaxy within which the appearance of life is of negligible probability. So the number of stars in the galaxy that could are outside this band is a very small percentage of the total number of stars.

Of those stars, some are too young, too massive, too hot, etc. Some (perhaps most) sun-like stars won’t have a planet at the right distance, just by chance. And of course, even if the conditions are all perfect, we don’t really know whether the appearance is an inevitability of the laws of chemistry, or if it depends on some chance event to pass any barriers to its development.

All in all, it is hard to say that intelligent life doesn’t exist elsewhere in our galaxy, but we should not be surprised to find out that it doesn’t.

Back to perpetual motion. Science fiction writers rarely propose such devices, but rarely do they fail to propose faster-than-light travel. Just to see how much this genre affects public science awareness, it is almost always taken as a given that an advanced race could break this barrier. It can be no more so than it could be that they build PMMs. So, EVEN if there are, let’s say, a thousand planets harboring intelligent species in our galaxy, the chances of our managing to contact them is vanishingly small as things stand.

17

Wow! I really should have edited that before posting. Sorry. I hope my meaning was clear anyway.

18

Allow me to drone on for a bit here…

Do I believe that intelligent life exists in the Universe? Oh, sure - the Universe is incredibly vast, and there’s plenty of room for just about anything in there. how vast? I rummaged through NASA’s web site, and came up with the following statistics: there are approximately 200 billion stars in our local galaxy, about half of which are as old or older than our sun. There are several billion galaxies in the Universe, and ours is about average in size. When Carl Sagan drones on about “billyuns and billyuns” - he’s right.

Let’s assume for a moment that the odds of intelligent life surrounding any particular sun are only one in 200 billion - IE, that you’re only going to find one intelligent species in an entire galaxy. That still leaves room for several billion intelligent species.

I personally believe that the odds of intelligent life evolving are actually quite higher - but I also believe that the odds that we’re ever going to be able detect any using the methods that are currently at our disposal round out to zero. (Note that I’m not saying that we’re not using the best methods we can - I’m saying that the best methods we can use aren’t good enough.)

Consider this: The electromagnetic waves that we’re currently using searching for in our quest for intelligent life (radio waves, etc) are items that we ourselves couldn’t have generated just 500 years ago - and can’t ourselves generate today in anywhere near the magnitude that a species identical to us in a faraway star in this galaxy would need in order to detect us. (In fact, the power we’d need to get to this magnitude would probably cook our solar system.) And the power required to send a signal to one of the other billion or so galaxies is much higher.

Hey, we can only detect planets circling nearby stars if the planets are the size of Jupiter and only several diameters away from their home star, and we can barely detect a nova in another galaxy (supernovas, yes - novas, no) - how are we going to pick up an alien’s equivalent to WKRP in Cincinnati?

Now consider that five hundred years in the future we’ll probably think of radio waves the way we now think of smoke signals - quaint and faintly amusing, but hardly a practical method of communication. A thousand years from now we’ll probably be using methods of communication that are simply undetectable using today’s technology.

Look at it this way - if another species hasn’t managed to travel to other stars (IE, they’re still home-planet-bound), they’re not going to be able to generate non-directed signals powerful enough for us to be able to detect them (and they’ll certainly have no reason to direct their signals towards this particular end-of-a-spiral-arm in Yet-Another-Galaxy). If another species has managed to break the barriers of their local solar system, they’re using technology that we can’t even detect to do it - and they’re probably using FTL communication technology that we also can’t detect.

(There’s also the possibility that, say, intelligent species of Granite might have no interest in generating radio waves or other methods of communication that we can detect, but for the sake of this discussion let’s just declare all non-comunicative chunks of Granite to be non-intelligent.)

What we’re doing today in our search for extraterrestrial life is the equivalent of standing atop the World Trade center in New York, staring intently towards the East looking for smoke signals from England. In the first place, any smoke signal generators the Brits require for their normal conversation won’t generate signals powerful enough for us to detect in New York. In the second place, most of the Brits gave up smoke signals for cell phones long ago.

Hey, by all means, stare away. But don’t get discouraged just because you can’t see anything.

19

What if they set all of France on fire? It might be worth an experiment to find out. :rolleyes:

20

Polycarp, I think that the binding energy of silicon actually proves my point. I could be wrong, but a silicon based entity would require a very long lifespan if it were to have a complex “multicellular” composition. Assuming (and this premise being weak) that the evolution of the species was relative to our own in terms of time, the predecessors must have existed hundreds of thousands of years ago. Sol is located on the perimeter of this galaxy and is quite young in a cosmological sense, but there are stars in the center of the galaxy which are much older and I would venture to say several supernovae in this dense location to produce the elements in question.