Why do scientists feel all extraterrestrial life forms must ahere to the rules of earth?

Question

i.e. they must breath air, they would not be able to live in extreme temperatures, they have to eat, etc. etc.
Why couldn't a being live on Mercury, not require sustanace or water, and still be intelligent and reproduce?
Why must everything conform to our preconcieved notions of how things are?

Answer 1

It's because we are the only planet with living beings that we know of so we only have Earth as an example of what living things need.

Answer 2

Because we're such an egotistical race that we think anything or anyone that doesn't adhere to those preconceived notions you mention as being inhuman and probably war-mongering. All you have to do is look at the hot springs surrounding volcanoes in the oceans and elsewhere and you'll find all kinds of life that doesn't conform to the norm. We ought to be ashamed of ourselves for even thinking we're such a superior race!

Answer 3

Steve, good question. I think it has to do with the fact that the planets that we can observe in our own solar system seem to appear to not be inhabitable. (not the right conditions for life as we know it to flourish).

If you do enough research though, you will find people questioning that every day. I was researching some information on planet earth this afternoon, and came across a website that had some awesome photos and good arguments about what we think we know and what we are told about life existing elsewhere. (It seems somewhat like a conspiracy type site, but you may like it:)

http://xfacts.com/mars_sub.htm

Answer 4

"Scientists" do not feel this.
Some science-fiction writers might as they use aliens as metafors for human conditions.

The rules of Science do require that they conform to universal laws like gravity, mass, velocity etc and their evolution as life forms is most suited to their environment.
Do you require that life forms reproduce and are "intelegent"?

PS most lifeforms on Earth do not breath air; many survive in extreme temperatures like volcanic vents etc.

Answer 5

Excellent Point.

Infact it is most likely that if an extra-terristrial being is ever found, it will be most unlike what we see in movies like ET. They are likely to be thankful to Sulphur and Nitrogen (and god knows what) - the way we are thankful to Water and Oxygen !

Infact they may even lack a physical form !

Answer 6

coz these factors are imp. for survival but they could be wrong