Do you believe in aliens from other planets?

[RedsBaron]

Why is it that when the potential for life in other places is discussed on TV or whatever, they very often rule out certain locations as uninhabitable? I've heard them say things like "it's too hot", "it's too cold", "its gasses are poisonous", etc. My question has always been "So, what if their bodies are equipped to like temperatures of 500 degrees? What if those "poison" gasses suit their "lungs" just fine? Why is the definition of what is fit for life always based on the assumption that the rules of earth apply everywhere?

I have a theory about the potential for alien visitors. It's based on an episode of The Twilight Zone. (Okay, stop laughing or rolling your eyes - I'm being serious here. Keep in mind that I'm no physics expert, though.)

In this episode of the Rod Serling classic, human space travelers arrive on another planet and find that everything and everybody looks pretty much like Earth. Thing is, nobody or nothing appears to be moving. They later discover that everything is, in fact, in motion, but it's going so slowly that they can't detect the movement, much as we don't see the movement of hands on a clock. As best I remember, the people on this planet didn't know they were there, because they were moving so fast in relation to how fast those people's brains detected and processed speed, much like we can't see a bullet when it's shot from a gun.

So, is it possible that people are visiting right now, and we just cant see them because they're so fast in relation to what our brains can process and our eyes can see? Or do I need to stop taking Rod Serling so seriously?

The original Star Trek had a similar episode.

[LvJ]

By God, I believe in Tom Cruise! :dancingco

[GAC]

Any civilization with the technology to get here from the nearest inhabitable planet would probably be that much more advanced than us socially also. It would be like watching an ant farm for them.

Do you talk to the ants in your ant farm, and let them know what you're doing up there?

Plus, I know for a fact that several of them post here.

Shhhhhhhhhhhhh.

[Larkin Fan]

There's already evidence of bacterial life on Mars.

There's also biochemical evidence of life on Mars as well.

It's unrealistic to me to think that Earth is the only planet that has life on it.

[oneupper]

Well, if you would just consult the guide, you would know that humans are only the third most intellegent species on earth.

http://hitchhikers.movies.go.com/

So the answer to the question must be 42.

[MrCinatit]

So the answer to the question must be 42.

SHHHH! we'll be blowed up!






(think about that one for a while)

[oneupper]

SHHHH! we'll be blowed up!






(think about that one for a while)

Hey. I'm cool...I've got my towel.

[RFS62]

Don't panic.

[Red Leader]

Stay hot.

[savafan]

There's also biochemical evidence of life on Mars as well.

It's unrealistic to me to think that Earth is the only planet that has life on it.

I believe that the Viking orbiter also sent back pictures of pyramids and dwellings on the surface of Mars.

[Redsland]

As far as the microbial evidence and biochemical evidence of Martian life, those findings are hotly debated. The scientific community, generally speaking, is not ready to say that they've found anything definitive. Particularly if you’re speaking of the chemical reactions detected during experiments by the Viking probes.

As to macro's question about the conditions for life, that is a very good question. We have only one set of examples of living creatures to study, and so exobiologists tend to make their assumptions about alien life by extrapolating from terrestrial life. Exobiologists realize that it's a dicey proposition to extrapolate from only one example.

That said, it is generally accepted that life requires chemical reactions, like the ones that allow us to turn food into energy and structures. Further, it is generally assumed that the structures would be built out of a plentiful resource that would necessarily be very chemically reactive. The sixth-most common element in the universe is carbon. Among the plentiful elements, it has unique advantages when it comes to reactivity.

We are based on carbon probably for these reasons. It is plentiful and it is versatile. Based on these facts, it seems logical to assume that it’s the most common organic building block out there. (Other possible elements, like silicon, are significantly less plentiful and chemically weaker.)

The chemical reactions taking place to sustain life require a solvent. Here we use water, which is made up of hydrogen and oxygen, which are two of the most common elements in the universe. Water has a great capacity to dissolve substances like life-sustaining chemicals, a great capacity to carry heat and regulate local temperature, and exists in liquid form across a wide temperature range. No other solvent we know of combines these advantages.

So, again, based on the fact that water is plentiful and versatile, terrestrial life uses it, and, we assume, extraterrestrial life does too, by and large.

Once you make the assumption that most life is carbon-based and most life requires water, you place great limits on the kinds of places where life can arise. Water, for example, exists in liquid form across a certain range of temperatures and pressures. A place that’s too cold for liquid water won’t be able to use it in the creation of life. At the same time, you place great limits on the physical tolerances of creatures, since carbon burns and water freezes.

In large part, two things drive all of these assumptions. First, that the universe, like the earth, uses the simplest solution and/or most plentiful resource most of the time. Second, that the periodic table shows you, in rapidly decreasing order, the relative abundance of elements. After that, it’s all chemistry.