Hawking's analysis strikes me as somewhat misguided, mostly because he's underestimating the effect of interstellar distances on the politics of space exploration. Most serious thinkers have long since discarded the hope for interstellar transport of human beings happening in our lifetimes. Simply put, launching anything into space and sending it out to distant solar systems takes an absolutely enormous amount of energy. Moreover, assuming the impossibility of faster-than-light transport of substantial matter, it takes a very long time to get from Earth to anywhere that might possibly have advanced life. Because of these two limitations, the search for inhabited planets will probably only ever be undertaken by an extremely advanced society with a nearly infinite supply of energy. Anyone who's witnessed the struggle over NASA funding should recognize this: it's one thing to wrestle over how much to spend on satellite designs that may well be incorporated into Pentagon satellites used to track terrorists--thus providing a concrete, near-term benefit. To spend unimaginable sums of money or resources to put an exploration team into space and *probably never hear from them again for the rest of your civilization's existence* requires practically free energy and a strong sense of curiosity.

So it's safe to say that we won't, ourselves, ever colonize inhabited planets to strip *their* physical resources...it's economically ludicrous. And we can assume that these assumptions mostly hold for extraterrestrials. We don't know how they'll generate their energy, but they'll still need lots of it, and we shouldn't predict that they'll manage faster-than-light travel. If the future conquerors of our planet have essentially unlimited energy, what sort of resource constraints would they face? *Our* resource constraints are primarily energy-related, and if we had an unlimited supply of it easily accessible, we could manage much better any non-energy constraints we face. Are we running our vehicles on lithium batteries but running out of lithium itself? We'll recycle our trash and figure out how to separate lithium from the other metals. To imagine a resource constraint that would require interplanetary travel in order to solve, we'd have to imagine a problem so difficult that an *infinite application of energy* cannot solve. Finally, for the natural resource dilemma, Professor Drezner's third question is most salient. Presumably a clever, space-colonizing species would also be able to quickly search for and locate the presence of any necessary resources, and that humans would merely be a distraction.

Might the aliens invade us in order to settle here, solving underpopulation? Unlikely. They would have their pick of thousands of nearer worlds, and unless their planetary requirements were very close to ours, they'd find our world almost as inhabitable as any other world. If we wanted to settle another planet, our method would *not* be to find intelligent life and then settle that planet--we'd pick the most suitable nearby planet and terraform it to our satisfaction--much easier than fighting against an alien species.

So if another alien species arrives, I'd expect it to be for similar reasons as we might visit another inhabited planet--simple curiosity. I don't expect, for example, a race that has the foresight to send pioneers on a thousand-year exploratory mission to exhibit violent xenophobia directed at the first alien race they find...what would be the purpose of that mission? Instead, I'd guess that they'll be trying to figure out how this strange species thinks and operates--an instinct that, as this blog entry proves, seems to be universal.

Can't help but suggest Alex Wendt's (nonsensical) article on IR and UFO's. The questions he and Raymond Duvall raise are of a whole different order, and they are even funnier because they're really serious about them. http://ptx.sagepub.com/cgi/content/short/36/4/607

I know you're funning (and I do like these posts, along with the zombies!) but if you can spare the time I strongly recommend reading "Forge of God" and "Anvil of the Stars" by Greg Bear.

I don't want to spoil a good read for you, but suffice to say they explore a fictional account of the issue mentioned in quite a bit of detail, along with some fascinating supposition on responses of human governments,

I think you now have a sequel for the Zombie textbook.

welcome our new jellyfish masters!

"If Hawking is correct, then the sooner we run out of whatever might be valuable to aliens, the less interest we are to them."

You don't need aliens for that scenario, I'm afraid. There is a good case for the idea that it's in a militarily weak oil producing country's interest to pump their oil as quickly as they can. Sure, they can get more money for the oil later on when it becomes rare, but only if no stronger country decides to invade or organize a coup to gain control of it for themselves.

As much as science fiction aficionados (myself included) might fantasize about it, contact with a technological extraterrestrial civilization is unlikely in the extreme -- if nothing else, because of the time scales involved.

We have been a technological race for how long? A few thousand years, depending on your definition. We're hundreds of years (technologically, politically, and economically) from interstellar travel, and perhaps thousands of years from widespread interstellar colonization.

But a few thousand years is nothing -- NOTHING -- compared to the age of the universe. Intelligent extraterrestrial life could have evolved anywhere in our galaxy any time within the last four BILLION years. So, by far, the likeliest scenario for encountering an intelligent extraterrestrial species is only by discovering their artifacts and empty ruins.

The next likely scenario is the ant-god encounter. Suppose we luck out and meet an intelligent ET species that evolved within the last million years (a tiny window of opportunity). We'll be ants in comparison, and they gods. Or, a million years down the road (if we luck out and don't destroy ourselves), we'll be the gods meeting the ants. Either way, resources won't be an issue. A species with technology advanced a million years from current technology will be able to manufacture anything they want from freely available base elements using abundant solar energy. And cultural exchange? Between an ant and a god? Forget about it.

Sad to say, in the (incredibly unlikely) ant-god event, the ant is probably going to get squished. As an annoyance, as an accident, or, taking the long view, to cut off a future rival. In this Mr. Hawking is correct. But the chance of it EVER happening, even should humanity last for another billion years, is infinitesimally tiny.

Ha!
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We're more likley to perish when the earth is destroyed to make way for a
hyperspatial express route.
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But come hell or high water, alien invasion or inter-steller highway, just remember always, and I mean always, know where your towel is. You have your towel, you don't need to panic.

Regarding your fifth question, what about the very real possibility that nuclear weapons cannot be depoyed or are inoperable in a zero gravity environment? Seriously, though - can you detonate a nuclear weapon in zero gravity?

Dr. Hawking raises some valid points (see also David Brin's 1983 paper The Great Silence which advocates radio silence for the same reasons). I wrote a book about SETI several years ago that details the strategies used in our search for extraterrestrial intelligence, and conversely that others can use to find us.

The problem is that, even if we were to halt all radio transmissions, Earth's atmosphere now contains clearly readable signals that betray our presence. Starting around 1900, the level of CO2 began to surge, which in of itself is not a sign of industrial activity, but is a signal that something interesting is happening. An ET science survey, similar to the planet finding space telescopes we have launched and will continue launching, would be able to spot this from afar (via a technique called spectroscopy, to analyze the color composition of light traversing the atmosphere, and hence its chemical composition).

But we have not just been injecting carbon dioxide into the atmosphere. We've also been sending up clearly synthetic compounds such as flourocarbons, that are strong indicators that something unusual is happening. Even if we somehow returned our atmosphere to pre-1900 conditions (not likely), that light signal or chemical fingerprint, like a radio transmission is traveling outward and can't be recalled. So anyone who has been surveying extraterrestrial planets as we just started doing in the 1990s will see that if they are looking, and probably guess that we're just entering an industrial phase of development.

Any civilization that is capable of interstellar travel will likely possess astronomical capabilities well in advance of what we have today, so we should assume they can see us, and in indeed, may have been studying earth's chemical evolution for a very long time (just as we've been studying Mars since we first discovered it).

The point is, the horse has already left the barn, so if there are aliens roaming our way, we'll find out sooner or later whether they are nice or nasty. There's not much we can do to conceal our presence at this point.

Most star-spanning alien civilizations (if any) would have solved the resource problem long before achieving interstellar capability. W/O a reason to invade and conquer worlds uncounted light years from their own contact with these should be relatively safe.

Unfortunately there's always the chance of running into the crazy ones. Klingons are a good example. In ST canon Klingons were "uplifted" by a neighboring alien power while they were still in a feudal, pre-industrial state. They transferred their intertribal penchant for warfare to conquering their neighbors and seizing their resources. It's not a viable culture - eventually they run into someone bigger than them who swats them down, but in the meantime they make pests of themselves. If our broadcasts reach the Klingons or Kzinti (another expansionist race from science fiction) we can expect alien battlefleets overhead in our future.

Or maybe not. The "sane" alien civilizations may take preemptive action against the crazies so they don't get annoyed either. it's not that hard to wreck a planet if you don't have to live there afterward. Said "Overseer" aliens might come along, find a planet with an emerging crazy civilization, and sterilize it on GP. That's the other thing we have to worry about - is "Mostly Harmless" good enough to let us live? Are we one of the crazies? Have we already been found, and are being judged now? Something to think about.

Not bad...until "Of course, this does beg the question of which resources aliens would consider to be valuable..." and "Which begs the question -- wouldn't Hawking's isolationist policy allow the quislings to monopolize the galactic message emanating from Earth?"

http://begthequestion.info/

Crazy old aliens may simply not want company in the universe and actively seek out alien life in order to kill it.

Another possibility is an alien Singularity event – they advance into something beyond our ability to understand and simply see our star system as matter to be converted into processing power.

Being alien, their motivations and reasoning might not make sense to us.

Hiding it isn't a bad idea, but I doubt it is possible.

Right now, alien scientists are no doubt studying Star Trek re-runs, trying to figure out whether they should annihilate us or preemptively surrender.

And what do we know about this Borg Collective that they keep hearing about?

It's obvious that any species that crawls from the muck to the stars is going to be the top predator on it's planet. So any real first contact is more apt to resemble Independence Day instead of Close Encounters of the Third Kind.

So I agree with Hawking. Let's keep a low profile. At least until we are ready to take on the galaxy. Which may be... never.

In the meantime, we have a more immediate threat to worry about, the Mirror Universe!

http://muchedumbre.com/mirror-universe-liberals

we'll be laughing ironically about while in the food holding pens of the Slarg Beasts.

But if your looking for good examples of human culture impacts, might I suggest the Japanese as the best of the lot. Totally isolated, when forced to interact they quickly adopted the alien west's technology, forms of economy and military knowledge base. The only mistake they made was to misjudge the timing of when colonialism was acceptable or not. Missing the mark by over 30 years, they found themselves on the wrong side of the imperialism curve and then managed to get into war with a future superpower.

All in all though, they came through it only losing a significant fraction of their total population and emerged as a fully fledged member of the new world order.

What Hawking is suggesting, however, is that efforts to collect such information would in and of themselves be dangerous, because they would announce our presence to others. He might be right. But shoiuldn't that risk be weighed against the cost of possessing a less robust early warning system? Isn't it in Earth's interests to enhance its intelligence-gathering activities?

If the destructive power differential is likely (as I think Hawking believes) to be nearly infinite but certainly overwhelming, and therefore we'd be basically defenseless, even with warning, then obviously Hawking is right that almost any increased risk of allowing them to detect us would be a dispositive indicator against efforts to gain greater intelligence.