Just because life here needs oxygen or carbon dioxide, water, a certain kind of temperature and to eat other living things for food surely doesn't mean that life on other planets requires the same.
2007-08-08 05:43:28 · 14 answers · asked by Anonymous in Science & Mathematics ➔ Astronomy & Space
That's absolutely correct
Alien life may not require water or oxygen but some other element
2007-08-08 05:47:56 · answer #1 · answered by Sad Roman 3 · 3⤊ 0⤋
There are at least three key ingredients to life that we can imagine: a solvent in which autocatalytic chemical reactions (precursors to life) can occur, a chemical species capable of making long chains or "macromolecules", and an abundant substance that helps drive metabolic reactions.
On Earth, we have water, carbon, and oxygen, respectively. Water is special because it is capable of dissolving a very wide range of solutes. It is a liquid within a relatively wide range of temperatures, and it is the only abundant compound that expands as it freezes. This last part is important because water ice floats in liquid water, which helps insulate the liquid underneath from the cold above, allowing oceans to remain primarily liquid even in harsh conditions.
Carbon is the only abundant species capable of forming large molecules. Silicon and oxygen might work together, but silicon isn't nearly as abundant in the universe as carbon.
Oxygen is a strong oxidizer, the strongest of the abundant chemicals in the universe. Chlorine might also have sufficed, but it is much less common.
It is possible that life could form in some other environment, and perhaps some day we will find lifeforms of a wildly different kind than what we've seen on Earth. Until then, it makes sense to look where we think we're mostly like to find something.
2007-08-08 06:01:14 · answer #2 · answered by Brent L 5 · 3⤊ 0⤋
I liked the start of Mr. X's answer regarding the temperature range of water but this, once again assumes that life on another planet MUST be similar to ours. Also, our understanding of life is in fact nothing more than our understanding of OUR life. We have no knowledge whatsoever of how life could evolve in entirely different circumstances.
Even on our own planet we know that we cannot breathe underwater without some form of artificial aid. So go tell that to an octopus! It's all about evolution and the simple fact is that, whilst we hate to admit it, we simply no nothing of what's going on out there on this subject.
2007-08-08 06:08:34 · answer #3 · answered by brainyandy 6 · 1⤊ 0⤋
Because Earthlings are extremely primitive. We have seen life evolve on what you could call ‘planets’ as small as what you call the moon. To add further to this, life does not necessarily need oxygen to evolve. If you require evidence, just look at your plant life; they consume carbon-dioxide.
Furthermore, we know that you Earthlings have discovered life forms on the bottom of your oceans, which is highly pressurized. It is due to the fact that you Earthlings use only 10% of your brains on your best days that you fail to consider how life can evolve in other galaxies.
2007-08-11 18:07:51 · answer #4 · answered by Anonymous · 0⤊ 0⤋
The reasoning for the requirements of life are biased strongly towards what we are familiar with. But it is not just familiarity that drives the decision.
We search for carbon based life because it is one of the few elements capable of making the complex structures required for life to exist. There have been theories as to silicon based life forms (Horta), but unfortunately silicon does not make the bonds as freely as carbon does. Highly unlikely for a natural phenomenon.
Liquid medium is crucial to allow chemicals to mix and bond into new molecular structures. Water is just simply the best medium. Liquid methane is another possibility (Titan).
You start with what you know and move on from there. We search for what we know because, well, its what we know!
2007-08-08 05:54:09 · answer #5 · answered by most important person you know 3 · 2⤊ 0⤋
The only life we know of if our own. So life as we know it requires the conditions we have on Earth.
We assume that life needs oxygen, food, water, heat.
There may be different chemical elements in a far off corner of our universe that we have not discovered. These undiscovered elements maybe able to support a life that we dont know about.
2007-08-08 05:52:53 · answer #6 · answered by Anonymous · 2⤊ 0⤋
I dont think its assumed that this condition is nessessary. However in our limited experience with lifeforms, we believe that a planet similar to earth will be the most likely candidate for finding life that we can identify as life.
Our definition of life may, however, be very narrow. We really don't know until we find something else.
2007-08-08 05:51:19 · answer #7 · answered by Anonymous · 3⤊ 0⤋
Exactly, there are some places we thought previously uninhabitable on earth and there is still life. There might be aliens looking at Earth right now, thinking 'that corrosive oxygen in the air, there can't possibly be life on this planet.'
2007-08-08 06:11:32 · answer #8 · answered by Grinning Football plinny younger 7 · 2⤊ 0⤋
That is the only form of life we know of, so until other evidence exist of a totally different type of life form, we have to assume this is the only situation under which life can form. That is just the way science works, you look at the evidence and form a hypothesis that is assumed true until it is disproven.
2007-08-08 05:53:58 · answer #9 · answered by Anonymous · 1⤊ 0⤋
it doesn't NEED to be, but our understanding of life tells us that liquid water is necessary. water is only liquid at a very narrow temperature range, and that has to do with the size of the planet and the distance from the star. it makes sense to start with planets that are somewhat similar to ours.
2007-08-08 05:48:19 · answer #10 · answered by Anonymous · 3⤊ 0⤋