Do you believe in aliens? [split]

[Sisyphus]

There is some reason to expect that life elsewhere would be something like life on Earth. Carbon is the most common efficient building block of complex molecules, and carbon compounds function best in certain types of environments. There would likely be a huge variety of life, some of it nothing like Earthlife, but that variety would probably include some that would be not too different from us. And by "us" I mean DNA-based life, cells with different functions, etc. I don't mean humans specifically, since the more complexity you have, the more different possibilities you have, and the less likely to find two of a kind evolved independantly.

[bombus]

Alien life could be extremely rare, and may not exist anywhere else in the universe. This could be it, the only island of life in all the black immensity of space...

 

For life of our kind to occur on earth the following was required:

 

1. A sun of the right size and type

2 A planet of the right distance from that sun

3. A planet of the right size

4. A planet that had been hit by a similar sized object at just the right point in its formation causing it to melt and allowing the core, mantle and crust layers to precipitate out (this is a really, really, really rare thing you know!)

5. A planet that has a single moon of the right size orbiting at the right speed and at the right distance.

6. A planet that spins at the right speed.

7. A planet that wobbles slightly on its axis.

8. A planet that has a slightly tilted axis.

9. A planet that has a magnetic field strong enough to deflect harmful solar radiation.

10. Volcanic activity and moving plates.

11. Liquid water.

 

All these things enabled life to exist (alledgedly). Venus and Mars are both almost OK for life, but are missing some of the above and so appear to be lifeless (but maybe we'll get a nice surprise someday?).

 

As for aliens visiting us - any society capable of interstellar travel would have probably destroyed itself long before by wasting all its resouces on cars, televisions, mobile phones, fashionable clothes, cleaning products, singing plastic wall mountable fish, and all the rest - and finished off by destroying their planet's life sustaining environment!

[Dr. Dalek]

Very pessimistic, I also must add it's rather absurd to assume that it is so likely for a civilization to destroy itself, and everything around it.

Aliens would not be likely to have the same kind of motavations as humans do for making weapos of mass destruction, or massive pollution, or such wasteful things as plastic mountable fish. How do you know they would even have fish on their planet?

There are a thousand ways for a civilisation to be destroyed, not all of them are self destruction.

Besides life on their planet would not nessisarily have gone caput with them, the biggest environmental dissaster on earth happend over a billion years ago when life began poluting it's own atmosphere with a chemical which was back then very poisonous. Oxygen.

Only the extremophiles, aerobic life, survived and look what they have become. Us.

[bombus]

Very pessimistic' date=' I also must add it's rather absurd to assume that it is so likely for a civilization to destroy itself, and everything around it.

Aliens would not be likely to have the same kind of motavations as humans do for making weapos of mass destruction, or massive pollution, or such wasteful things as plastic mountable fish. How do you know they would even have fish on their planet?

There are a thousand ways for a civilisation to be destroyed, not all of them are self destruction.

Besides life on their planet would not nessisarily have gone caput with them, the biggest environmental dissaster on earth happend over a billion years ago when life began poluting it's own atmosphere with a chemical which was back then very poisonous. Oxygen.

Only the extremophiles, aerobic life, survived and look what they have become. Us.[/quote']

 

If evolution works the same on another planet (I can't imagine why it would not) I would assume that aliens would have very similar drives and emotions as us. It is perhaps possible that a highly technological civilization could emerge out of a 'hive' society, but in my opinion, unlikely. Technology is essentially the result of very well developed brains - individual intelligence, and that is just not needed with 'hive' societies.

 

You are right about previous mass extinctions of course, but I never said it would wipe out all life on Earth. However, the fact that life tends to bounce back does not mean that intelligence life does. While human activities may destroy the planet for us, other things will probably get on fine - insects, bacteria, plants, whatever. Maybe evolution produces intelligence every now and then, but it never lasts long and isn't a very good evolutionary path to follow.

 

As for aliens not destroying themselves like us foolish humans, lets hope you are right. It would at least give us some hope for the future!

[ecoli]

If evolution works the same on another planet (I can't imagine why it would not)

The chance that this is true is very small. Evolution is based on very specific conditions. It would be foolish to assume even that aliens would have similiar emotion and needs as us.

[Dr. Dalek]

"Hive" may have been the wrong term, "communal group" would be more appropriate after giving it some thought.

All the same I do not think that it is inevitable, or even nearly so, for a intelligant species to destroy itself.

Also alien evolution may have some parallels to earth. After all eyes, an important sensory organ, developed on earth for the first time in two evolutionary separated groups. Mollusks, and vertebrates. No creature in the two races common ancestry had anything like eyes, yet both developed very similar eye anatomy. This is an example of parallel evolution, two different types of life with similar requirements, or in some cases ecological niches, will occasionally develop very similar traits.

Another example would be the similarity between rodent, and rabbit related species. Some people, assume rabbits and rodents are closely related. They are not, they have similarities because of common ecological niches.

[Dr. Dalek]

"No creature in the two races common ancestry had anything like eyes, yet both developed very similar eye anatomy."

I apologise the proper term is not "races" it is phylum.