There's no place like Home... or is there?

[Elheru Aran]

Okay, so I was musing earlier in the shower.

It occurs to me that, despite all the 'alien' environments talked about and the like, there should still be some constancy all over the place. Everything's made from basic elements, starting with hydrogen and building upwards, right? So, here's the question.

If, by some wonder, an Earth-like planet is discovered sometime in the near future, and a ship with a group of colonists is sent up there. I'm thinking they would discover that everything's basically the same-- rock is rock, wood is wood, water is water, and so on-- perhaps with a few additives, perhaps some slightly different combinations, but basically they'd be the same thing. In fact, I remember the TOS episode with Kirk and the Gorn-- Kirk was able to make crude gunpowder with sulfur, charcoal and saltpetre, which he discovered on the planet.

So why do most authors postulate totally different environments, elements and materials for alien cultures/planets? I mean, we aren't discovering any wank metals or anything-- about the only thing we can realistically expect in the near future is better alloys and more composite materials. The periodic table isn't about to change anytime soon.

There you go, I guess...

[Xenophobe3691]

Okay, so I was musing earlier in the shower.

It occurs to me that, despite all the 'alien' environments talked about and the like, there should still be some constancy all over the place. Everything's made from basic elements, starting with hydrogen and building upwards, right? So, here's the question.

If, by some wonder, an Earth-like planet is discovered sometime in the near future, and a ship with a group of colonists is sent up there. I'm thinking they would discover that everything's basically the same-- rock is rock, wood is wood, water is water, and so on-- perhaps with a few additives, perhaps some slightly different combinations, but basically they'd be the same thing. In fact, I remember the TOS episode with Kirk and the Gorn-- Kirk was able to make crude gunpowder with sulfur, charcoal and saltpetre, which he discovered on the planet.

So why do most authors postulate totally different environments, elements and materials for alien cultures/planets? I mean, we aren't discovering any wank metals or anything-- about the only thing we can realistically expect in the near future is better alloys and more composite materials. The periodic table isn't about to change anytime soon.

There you go, I guess...

Because we're all the children of right-handed proteins, and left-handed proteins do nothing to us...

Meaning that we can have a world almost exactly the same, but something as simple as the "handedness" of a basic protein can screw it all up.

[Slartibartfast]

While wood is specific to a certain kind of lifeform, what you said should apply to most other basic compounds.

[wolveraptor]

It depends on what you consider "similar". Venus is quite similar to Earth in some respects.

If you're implying that you'd find aliens with five fingers, familiar skeletal structures and even some recognizable facial features, I'd have to disagree with you. We are what we are because we descended from arboreal apes, which do not have to develope intelligence on those other worlds. It was the drying of Central Africa that forced apes down from the trees. That might not have happened if we re-ran Earth.

[Elheru Aran]

It depends on what you consider "similar". Venus is quite similar to Earth in some respects.

If you're implying that you'd find aliens with five fingers, familiar skeletal structures and even some recognizable facial features, I'd have to disagree with you. We are what we are because we descended from arboreal apes, which do not have to develope intelligence on those other worlds. It was the drying of Central Africa that forced apes down from the trees. That might not have happened if we re-ran Earth.

I'm not. I'm just asking, basically, why most sci-fi writers portray most worlds as totally different from ours, with different elements and the like, when logically many things should still be much the same-- stones, fluids, gases, and so forth...

[wolveraptor]

Well, maybe they only do that when the conditions on the planet itself are very different. Extreme heat would make certain elements react differently, though logically, on an earth-like planet, there should be stones, water, and the basic stuff.

[CaptainChewbacca]

I'm going to agree that if you define an earth-like planet as being 93 million miles from a G-type star with a surface gravity of 1G and an atmosphere containing 71% nitrogen, 19% Oxygen, and components, with an active lithosphere and hydrosphere, you will find similarities in organisms.

But, that's a pretty specific definistion of earth-like.