Why do we assume aliens require a planet similar to our own?

Question

Is our imagination so limited that we assume aliens require oxygen and liquid water? Or indeed a planet at all?

Answer 1

Good question....now you got me thinking. If aliens are supposed to be so diverse, why would they need oxygen, liquid water, or a planet at all? Of course, they would need something to live, but then again, who knows that they don't create their own oxygen or something. Very good question....

Answer 2

Firstly consider all life on the Earth, There must be thousands of different species on Earth and not all of them require water or oxygen or even both of these to live. For example take a microscopic bug called a Water Bear it can survive in temperature's as low as -279 Celsius and can survive in space as well. So what would life be like on other planets they may be humanoid but I very much doubt it. There may be simple life like algae or even trees and plants they are also considered a form of life. Or there could be life which is a cross of any of the species on Earth.

I hope that this answers your question?

Answer 3

For life to evolve a planet similar to ours is probably not a requirement. In the coming decades, as NASA and the Europeans explore our solar system this question will likely be answered - consider the possibilities of life on Mars and the moons around Jupiter.

For life to evolve, though, a planet is required as this provides all the resources for that life-form to manipulate and harness for its survival and evolution. Although, scientists say that the building blocks for life on Earth may have originated in deep space, which impregnated the earth via a comet, that material is of no use unless it can feed off of matter and grow.

Answer 4

I think it's it has more to do with the money television companies and film studios are prepared to invest in science fiction, it's about appealing to as wide an audience as possible,
whereas in reality the ideas that have been coming out of the imaginations of science fiction writers for decades now, seem to know no limits.

Answer 5

Aliens probably are specified by some sort of
DNA.
It the conditions of a planet varied too much from ours these chemical reactions may never take place.

Answer 6

Life is based on complex molecules which can only be formed from carbon or silicon. These chemicals need to be disolved in a solvent such as water which needs to be in a liquid state, it is possible that this can happen in liquid methane (Titan) though this requires a more complex chemical pathway.
Liquids only occur in planetary conditions, in deep space things are either gas or solid.

Answer 7

We don't... at the end of the day its perfectly possible that life exists in adverse circumstances, we've seen on our own planet that life can spring up in what we would think is impossible...

we havn't ruled anything out, we just know from experiences on our own planet that the best indicator of an environment that supports life is water... beyond that we really don't care...

Answer 8

I never did I have seen them on like moon planets no or little amosphere they where hardy like they where made out of soft dense clay. Other aliens here need a thin atmosphere of like some kind of sulfaso they pump it into the atmospher on earth.

Answer 9

For that matter, why do we assume that aliens look similar to us? In many science fiction shows, the aliens may have horns on their head, or have leathery skin, etc., but otherwise they basically are humanoid. What's up with that? Good question!

Answer 10

Because the current 'model' that we base life off of requires water, and sometimes oxygen. Right now we are making conclusions based on the information we have available to us. If we found out that life could exist in the vacume of space, we could add that to our model of understanding.