Why do scientists stick to the absence of liquid water on other planets as evidence of "no life"?

Question

Are scientists being narrow-minded by considering water as necessary for ET life to exist? Also, how can they be sure that life, if any, can't do without oxygen? I mean, well, water and oxygen are key elements for life on earth, but is there not a tiny teeny possibility that ET creatures are just so different that what we need is not what they do?

Answer 1

Well, I don't think anyone can be arrogant enough to rule out the possibility that extraterrestial life must live on what we live on. After all, we haven't yet met one such existence (or we don't yet know we have), so our knowledge of them, if any, is just incredibly limited.

And if they are so different that they are wildly out of our reasonable imagination in terms of the way they live, it's also probable that their appearance is literally "unearthly", so much so that we are unable to detect them in their presence. The search for them is perhaps as "stupid" as if we make the assumption that they live on water. So a starting point is kind of a trade-off: we assume they share some basic features of earth life, only so can we start to look. This assumption might be misleading, but without it, the outlook of the search is perhaps no better.

Answer 2

Oxygen is not at all needed for life. There is tons of life on Earth that doesn't need oxygen. They're called plants. They use carbon dioxide and create oxygen.

There is not a single life form on Earth that can survive or develop without water in some way. Oxygen however is definitely not necessary.

Answer 3

It isn't that scientists say there will be "no life"without liquid water.It is more that we are just beginning,relatively,our space exploration.Missions are quite costly within the solar system,currently impossible outside the solar system.We can not yet even directly see extra solar planets.We can deduce their presence from the star's wobble.The life that we know of is dependent on liquid water,so as a first step towards finding life,naturally we will concentrate on what we know.
You are correct,there is no "LAW"that says life MUST have liquid water,or oxygen,but when you are throwing a dart basically blind.You would want to narrow it down at least to what you already know.I'm sure we will eventually come across very bizarre life "out there",but,until we reach the "star trek"level of technology,where we can zip freely between solar systems,it is simply more economic and sensible to pool our resources toward finding what we already know can sustain life

Answer 4

No. Here is an example. A sterile neutrino is a hypothetical neutrino that does not interact via any of the fundamental interactions of the Standard Model except gravity [1]. It is a right-handed neutrino or a left-handed anti-neutrino. Such a particle belongs to a singlet representation with respect to the strong interaction and the weak interaction and has zero weak hypercharge, zero weak isospin and zero electric charge. Sterile neutrinos would still interact via gravity, so if they are heavy enough, they could explain cold dark matter or warm dark matter. In grand unification theories such as the Georgi-Glashow model they also interact via gauge interactions which are extremely suppressed at ordinary energies because their gauge boson is extremely massive. Sterile neutrinos may mix with ordinary neutrinos via a Dirac mass. The sterile neutrinos and ordinary neutrinos may also have Majorana masses. In certain models, both Dirac and Majorana masses are used in a seesaw mechanism, which drives ordinary neutrino masses down and makes the sterile neutrinos much heavier than the Standard Model interacting neutrinos. In some models the heavy neutrinos can be as heavy as the GUT scale (~1012 GeV). In other models they could be lighter than the weak gauge bosons W and Z as in the so-called νMSM model where their masses are between GeV and keV. Light (with the mass ~1 eV) sterile neutrino was suggested as a possible explanation of the results of LSND experiment. On April 11, 2007, researchers at the MiniBooNE experiment at Fermilab announced that they had not found any evidence supporting the existence of such a sterile neutrino.[2] More recent results and analysis have provided some support for the existence of the sterile neutrino.[1]

Answer 5

Scientists can only rely of earthly experience.
There is absolutely no proof that extra-terrestrial life exists in the universe but it is the most likely thing that is possible without proof.
ET would likely be based on some type of DNA not much different than ours
ET would be intelligent,technological and objective,they would likely parallel in just about every way,with all our problems and success.
Without any evidence to the contrary it is likely liquid water would be essential to their existence.
You could postulate something like silicon but it would be wild speculation.
We probably may never know,but chemists could one day,through experiment,suggest a viable alternative to carbon and water.
All in all ET is surely out there speculating about us as we do about them.

Answer 6

People who ask this question always leave out an important piece. The scientists you so blithely criticise are searching for life AS WE KNOW IT. Yes, there are many possibilities, but as far as we know based on our own experience life requires the complexities of carbon's chemical bonding capabilities and liquid water. Since that is all we know for sure about life on this planet, it makes sense to search for similar conditions in space, otherwise how would we know life when we find it? The search has to start somewhere, doesn't it.

Answer 7

Sure different life can have different evolutionary twists and turns. For all we know on some distant planet 1,000,000 light years away there are creatures living with absolutely no o2 in the air. It is quite impossible to guess what other ways something could possibly live because the stages of evolution are unpredictable.

Answer 8

most of the universe is carbon based. As far as we know(and thats all we can go on) carbon based life requires water to live. There are bacteria on earth that do not need oxygen.

Answer 9

Most modern science is scaled toward "life" being carbon-based, and requiring certain criteria to be met in order for "life" to exist.

Most scientists are too narrow-minded or arrogant to accept that they might just be wrong, and that carbon-basing and carbon-dating may not be the "flawless, irrefutable standard" that they have come to believe it to be.

Science is, for as much as many would disagree, as narrow-minded a field as religion and, in many instances, even more so. Most religions teach followers to forgive the non-believer. Science teaches it's followers to disprove the non-believer.

Answer 10

An excellent question. I am not schooled in science myself but given the vastness of space and our relatively limited knowledge of it it would seem that they should not be "boxing themselves in" based on so limited a criteria...wouldn't it?
You sure got my attention.
But then again I barely graduated highschool.....I just love to learn...and question...as you are doing now.
Thank you.