The Plausibility of Alien Life

bluescat48 writes:

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If such life was advanced, far beyond our own, the yes it would be plausible that alien life could travel to our earth.

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Do you agree or not and why?

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"Could"? Yes, insofar as there is a physical way to have it happen."Plausible"? No, for reasons of space, time, and materials.Space is huge. It would take an extremely long time to cross it. Pioneer 10 took 36 years to go only 90 AU. Voyager 1 is going faster, it's the fastest thing we've ever made (17 km/s), but 30 years to go 108 AU is still slow. That's only 5.7e-5 lightyears per year. Just to reach Alpha Centauri (which Voyager 1 is not headed toward) would take more than 70,000 years.If a living being is going to make the journey, it is going to have to be able to survive what will likely be hundreds of not thousands of years to reach its destination. Somehow, it will need to be provided energy to maintain its biology as well as physical materials to sustain the physical body. As we know from thermodynamics, there is no way to perfectly recycle such energy and materials.And of course, there is the issue of slowing down. You can use gravity assists from the sun and other large bodies to get your speed up. Slowing down is another matter entirely. A lot of your energy stores are going to be needed to get you to stay near your target. Atmospheric braking would probably burn the craft up given the speeds it is going at so it would need an internal braking mechanism.Thus, they'll need to bring stocks with them...which will overwhelmingly increase the payload which will overwhelmingly increase the energy requirements. As soon as they get far enough away from their home star, they won't be able to rely upon sunlight to power their biology or technology. They will have to rely upon other sources such as chemical and/or nuclear, which means they're going to have to be more efficient than any known process if they hope to sustain it for the time required to cross the distance.By the time they arrive, the beings who show up will not be the ones who left. Let's assume that they could reach massive speeds. Even so, it would be the equivalent of asking the people of the 15th Century to embark upon a mission that won't produce any results for 500 years...and nobody left behind will ever learn the fate of the mission...and nobody on the mission will ever see home again.Now, I could envision a planet putting together every single resource it had upon building a device that might be able to do it (though I'm having a hard time with the mass/energy curve: The very material you bring along to power the system increases the power load required...there'd have to be some interesting gravity assists along the way in order to conserve that power for maintenance rather than motion.) But that is hardly "plausible."The only reason I could see to send a living being is if you were leaving your home for good.Now, there are some life forms that can go into suspended animation. So far, all the ones we know of are extremely simple forms. If we assume that somehow a way to keep large, multi-celluar life viable yet not active were discovered, a lot of the energy requirements would be lowered, but then you still have the problem of the vast time scales involved: Nobody who sends the people off will be alive by the time they arrive, if they return it will have been generations that have passed.This isn't to say that attempted communications with other worlds isn't of any worth. It's that trying to go there is so impractical as to be highly implausible to have ever happened. We didn't deliberately send Pioneer 10 towards Aldebaran. It's just a coincidence. That, I think, would be the most likely way we would come across a physical object created by an extaterrestrial species: Some sort of probe that due to a coincidence of geometry had it wander by this direction.

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Rrhain

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Thank you for your submission to Science. Your paper was reviewed by a jury of seventh graders so that they could look for balance and to allow them to make up their own minds. We are sorry to say that they found your paper "bogus," specifically describing the section on the laboratory work "boring." We regret that we will be unable to publish your work at this time.

Taz responds to me:

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People used to think flight was impossible. People never even imagined supersonic speeds. And even then, people imagined flight would be like people flapping their wings to fly more like birds.

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That's not the same thing. The amount of energy required to get a mass moving that quickly is decidedly non-linear. That's why nothing with mass can move at the speed of light: It would require an infinite amount of energy. Efficiency is one thing, but Scotty was right: You kinna change the laws o' physics.I don't doubt that technology will advance to allow greater efficiency. I suspect that a fusion reactor could conceivably be developed. But reactionless drives are the stuff of science fiction. Ion drives don't require as much fuel as chemical drives, but they have much smaller thrust in return and are also limited by the power required to generate the fields to a sufficient level to get that thrust.This is why I say I can conceive of it being done: Your spaceship is the size of a small asteroid and gets consumed in the process, but I certainly don't say it's physically impossible. I say it is emminently impractical.

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What you just said is little better than how people during Kristofer Kalumbus's period would describe intercontinental travel in the future.

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Ahem. Nobody said Columbus's trip was impossible. They said it was silly because the Earth was bigger than Columbus was saying it was. Nobody was saying the earth was flat. The Earth was known to be round from the time of at least Aristarchus. Instead, they were questioning his claim about the size.Columbus had a bad map and some bad math and made a calculation of the size of the Earth that had it about the size of Mars, if I recall correctly. And if the Earth is the size of Mars, then indeed it is a shorter distance to sail west from Spain in order to reach China than it is to go around Africa, assuming the Eurasian/African continental mass is as it is and you extract all the extra surface area from the American continents. But, Earth is much bigger than what Columbus calculated it to be and even though he found land where he said he would, it wasn't the right land. He got very lucky that the American continents were there otherwise he and his crew would have perished in the middle of a vast ocean.The universe is so large that the cost of sending a biological organism across the distances is impractical.

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Rrhain

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Thank you for your submission to Science. Your paper was reviewed by a jury of seventh graders so that they could look for balance and to allow them to make up their own minds. We are sorry to say that they found your paper "bogus," specifically describing the section on the laboratory work "boring." We regret that we will be unable to publish your work at this time.

Buzsaw writes:

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The following exerpt cites what appears to be some significant cosmological compatibility to life

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Your quote-mine assumes that there are no interdependencies. Why assume that given the nature of physics, protons could be anything else?Once again, you are applying significance to the Anthropic Principle: Of course we live in a universe that can support our existence. Where else could we possibly exist?I've been through this before, and so far nobody has ever answered:Suppose you have a standard deck of 52 cards.What is the probability of drawing the Ace of Spades?
What is the probability of drawing an Ace?
What is the probability of drawing a Spade?
What is the probability of drawing a black card?
What is the probability of drawing a card?You are confusing the probability of the first with the probability of the last. If things were different, then we'd be different. Another comment I make that nobody ever responds to:A parent and child are walking along when the child asks, "Why is the sky blue?""Well," says the parent, "If it were green then we would ask, 'Why is the sky green?'"To claim significance out of the fact that we live in a universe that can support our existence is to claim that the sky is blue specifically to allow us to ask the question, in English, "Why is the sky blue?" The sky is whatever color it is and we adapted to it.The universe is however it is and existence within it adapted to it.

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Rrhain

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Thank you for your submission to Science. Your paper was reviewed by a jury of seventh graders so that they could look for balance and to allow them to make up their own minds. We are sorry to say that they found your paper "bogus," specifically describing the section on the laboratory work "boring." We regret that we will be unable to publish your work at this time.

Parasomnium writes:

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Our atmosphere contains a relatively large amount of oxygen. This is indicative of life

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Um...that's indicative of life here. Who said that life requires oxygen? One of the big reasons we're looking at places like Titan is because it is at a triple point: Methane exists as solid, liquid and gas there much like water is solid, liquid, and gas here.And don't forget, for much of life's existence on earth, we didn't have oxygen. It's only recently that the atmosphere became heavily oxygenated. That there is oxygen in the atmosphere would be indicative of a chemical process, yes, but not necessarily life.

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Rrhain

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Thank you for your submission to Science. Your paper was reviewed by a jury of seventh graders so that they could look for balance and to allow them to make up their own minds. We are sorry to say that they found your paper "bogus," specifically describing the section on the laboratory work "boring." We regret that we will be unable to publish your work at this time.

Parasomnium responds to me:

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But I think we can at least agree that whatever causes so much oxygen in a planet's atmosphere is surely an interesting phenomenon.

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Eh. Not really. We find it interesting because we live in an oxygen-rich environment. Venus is filled with carbon dioxide. Titan is covered in methane. Io is overflowing with sulphur, so much that it's feeding a ring around Jupiter, if I recall correctly. All of this is interesting.Given that we have seen life in so many variations based upon just the one foundational chemical set of our own to the point that some thrive on oxygen while some shun it, I'm not sure that we can call an oxygen-rich environment a calling card of life. It's a calling card of our life and it would certainly be interesting to us.But that's just us.

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Rrhain

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Thank you for your submission to Science. Your paper was reviewed by a jury of seventh graders so that they could look for balance and to allow them to make up their own minds. We are sorry to say that they found your paper "bogus," specifically describing the section on the laboratory work "boring." We regret that we will be unable to publish your work at this time.