Is there another Earth out there?

USA Today ^ | Staff Writer

[bedolido]

Forget the next Star Wars movie. The real space sequel guaranteed to capture public attention, astronomers say, is the discovery of another planet like Earth in our own starry neighborhood -- and it is likely to happen within a decade.

[donh]

Solar sails may one day be a viable means of interstellar travel, but not right now, as the problems with solar sails are immense.

All that is necessary is that we build a ship big enough for people to breed aboard, say, inside an astroid with a wide eliptical orbit, and kick it out of orbit and on it's merry way with some kind of currently available thrust. If you have all the time in the world, you don't need very advanced technology. If you want to get to Beta Centauri by tomorrow noon on a regularly scheduled intersteller cruiser, that might not be in the cards. But, that wasn't the question asked.

[donh]

imply because there is an infinite amount of space for them.

By our current lights, this is not the case. The universe is finitely bounded by the expanding envelope started by the Big Bang.

[sandydipper]

Democrats are living proof that aliens have been here and had sex with buffalos.

[donh]

I must have missed a post somewhere

The original argument starts at post #7, and continues intermittently throughout this thread. I took up the argument in post #103.

[ASA Vet]

I assume that's high-level,
NSA code talk...

It's not.

[RightWhale]

Oh, okay. I was looking at that from another aspect. We must have looked at a dozen different math models for population growth in calculus class. Hard to know which they might have had in mind, if any.

[Frumious Bandersnatch]

In most predators, predation is very specialized and has a limited outlet. In man, however, this 'instinct' is very general. And as deadly as it can get in a traditional predator/prey relationship, it can easily find other outlets (business, sports, etc.). Basically we have the ability to create our own competition as well as destroy it.

[donh]

In most predators, predation is very specialized and has a limited outlet. In man, however, this 'instinct' is very general. And as deadly as it can get in a traditional predator/prey relationship, it can easily find other outlets (business, sports, etc.). Basically we have the ability to create our own competition as well as destroy it.

Which makes my point.

And, incidently, also does not make it a good thing, per se. To suppose that, unlike specialized predators, we are no longer contrained to equilibrium relationships with our environment, is, to my lights, a giant step backwards in moral instinct. It means that, unlike, say, wolves, who have quite a panopy of instinctive restraints on predatory behavior, we become more like opportunistic virus infections, eating our supporting environment until it is gone. This is not a step upwards in moral qualification as owners of the universe, in my humble opinion.

[Frumious Bandersnatch]

Actually, the utopian view that non-human predators have instinctive checks to their predation is not well-founded, whereas physical limitations are. In actual fact, it has been found that many (if not all) predators will slaughter prey just for the heck of it if they get a chance. Torture by predators of prey is not uncommon either.

But concerning your point that competition is not good per se, I agree. It is neutral and can be used for good or bad.

[theFIRMbss]

>I assume that's high-level, NSA code talk...
>>It's not.

"Look well at the rainbow.
The first will rise very soon.
Chico is in the house.
Visit him.
The sky is blue.
The fish is red."

[P.O.E.]

"There is a theory which states that if ever anybody discovers exactly what the Universe is for and why it is here, it will instantly disappear and be replaced by something even more bizarre and inexplicable. There is another theory which states that this has already happened."

- Anon.

[Grando Calrissian]

I should have referenced the quote:

The Hitchhiker's Guide to the Galaxy by Douglas Adams

[keats5]

Is there another earth out there?

God knows.

[donh]

Actually, the utopian view that non-human predators have instinctive checks to their predation is not well-founded,

Check out "Why Big Fierce Animals are Rare". Of course it's well-founded--it's just not a law of physics that can't be violated. To check this out, try to get an alpha wolf to neck-choke a supine pup it's angry at. Or try to get a non-alpha wolf to pair-bond in a turbulant situation.

At any rate, I'd hardly call female infanticide and a taste for inter-tribal war utopian.

[Boiler Plate]

I should have referenced the quote: The Hitchhiker's Guide to the Galaxy by Douglas Adams

I may not always have a towel on my person, but I always keep a towel in every car. Great book and very sound advice.

[BillCompton]

Fifth, you assume that superluminal or near luminal travel is something that is an eventual inevitability, for any given civilization. Moreover, that it is an attractive option for great numbers.

I mostly agree with the other points you made, but I don't agree with this one. It is only 100,000 light years across our galaxy. If 10% the speed of light travel is possible, it would only take 1 million years to travel from one side to the other. If only 1% the speed of light is possible, then it would take 10 million years. I don't at all assume near liminal speeds. So, if any life form a) could learn to travel through space by creating a space ship that could sustain a population and b) it tended to replicate itself, it would quickly spread everywhere in the galaxy. Also, it (the life forms) would quickly consume all the material in the galaxy. The galaxy is several billion years old. If you assume the 10% travel number, and nothing in physics that I am aware of makes this speed of travel implausable, if not easy. If you liken the age of the universe to a 40 year lifespan, a million years is only one day of that life. So, in a single day assuming that each space craft's split every 10,000 years on average, there would be 6 million trillion "space ships" for every star. I am assuming a "space ship" is ring shaped and many miles in diameter. I spins, creating simulated gravity. It houses a ecosystem and, provided there is energy, can sustain life for generations. If these ships split every 10,000 years, the numbers apply.

So I ask you, which of these assumptions is incorrect or not conservative?

Or look at it another way. Assuming mankind does not destroy itself in the next 10,000 years (a big assumption), Do you think it unlikely that we will create a ship capable of sustaining life through deep space? And, knowing how to do that, is it unlikely the space craft would seek to create others like itself once it found sufficient resources? And once several of these existed, isn't it likely that some would get good at doing this process?

Your arguments could apply to any specific instance. But if ever there was an exception, would it not be inevitable that life would expand to consume all the resources of the galaxy in a very short time? So, either we are the first, or we are the only, or through the craziest of coincidences, we came along on the same universe-day as another species with our propensities.

I understand that I have not proved that life does not exist elsewhere. But if, as some people think, life is common, wouldn't it be likely that some civilization would have done what life everywhere would have a tendency to do: Fill the void?

[BillCompton]

In developing and agricultural communities this is somewhat (though not entirely) true. In highly developed societies, life increase in an linear fashion. In some cases, it actually decreases significantly.

Your analogy is flawed. We are not talking about things with a human lifespan. A community venturing out into space would not die off after a century. So if people didn't die for thousands of years, what would happen to linear as opposed to exponential growth? If humans remained alive and reproductive for thousands of years, that would be a fair analogy.

Either these societies would learn how to live in space and to mine resources or they wouldn't. if they did, the geometric progression would apply until resources became scarce. That would be the only thing that could limit the progression.

[BillCompton]

And, some more points. What if we are the first (assuming we're the first, since we don't know yet)? Someone has to be first.. What if there are half a dozen other civilizations out there, with perhaps one or two expanding - slowly? What if the one - or twenty - that are expanding simply don't find our system especially suitable for their interests? What if we just can't recognize their communications? (Especially if they have a superluminal means of communication). What if they have much more languid reproduction rates; much shorter lifespans; what if they're marine? what if, what if, what if.. All we know is that at least one (but probably more) what ifs apply, assuming 'they' are out there, which they probably are..

I don't know how you can say they "probably" are. If life exists elsewhere in the galaxy, then it is "probably" not that unusual for life to form. Since the process is proven in at least 2 places, would it be "probable" that, given the billions of stars here that it would happen on a larger number? Your "what if's" could be true. But if there were ever an exception to your rules, that exception would quickly fill the galaxy. You might be right, but I don't know how you can say "probably" you are right.

[BillCompton]

Some fine points.

First of all, there's every plausibility that life is common but that technological civilizations do not arise fairly frequently. Out of millions and millions of species on Earth, only one has developed a technological civilization. Moreover, that particular evolutionary tree took some 600 million years in order to accomplish the task..

It is true, no doubt, that life takes a long time to develop. But earth has a 100% batting average at producing intelligent life. I don't think you can use Earth as an example of how intelligent life is unlikely to emerge.

Secondly, you again assume not only that other species would have personality characteristics conducive to interstellar expansion, but also that interstellar travel, migration, colonization, and communication are all relatively plausible, effortless, and attractive.

Your point, if I understand it, is that some intelligent life might have the characteristics you describe. My point is that if _ever_ there were an exception, that life form would quickly consume the galaxy.

What would they do once they're on that planet? What if the planet turns out unsuitable? What if they have a mutiny along the way? A civil war? They have to establish the colony. For what?

I agree that it has yet to be established that we can long exist with advanced technology. But if we can, then you have to assume a space colony would also be able to persist even with advanced technology. The engine for expansion, of course, is resources. When earth is out, which it almost certainly will be in a million years, what will man do? Die quietly? I doubt it. We will try to solve the problem. The only solution is too obtain resources elsewhere and we will seek to create habitats elsewhere. I think this urge, always assuming a super-bug doesn't wipe us out first, will inevitably lead to colonizing space.

The questions proliferate ad infinitum. The fact of the matter is that: we do not see indications of other civilizations, which suggests that other civilizations do not expand to fill the galaxy, and we don't know precisely why that is...

Why do you assume they are there?

[BillCompton]

(snip)

All this assumes that interstellar space travel is possible: my feelings are that for a civilization that has harnessed the entire resources of its solar system (including its Oort cloud), it is.

Beautifully put. I will read what Dr. Jill Tarter has written. Thanks for posting this.