Evidence for ET is mounting daily, but not proven.

[Trakar]

The core meaning is clear. When used in a scientific discussion, especially a speculative one, it is understood to mean "does not disagree with" rather than actively agrees. I don't think there's any excuse for "bristling".

I'd disagree with what you determine to be "clear," especially when the users of the language seem to be insisting on casual understandings and interpretations rather than employing stricter, and more proper scientific qualifications, only begrudgingly acknowledge the range of actual science evidences when dragged to them, and then use such casually misstated arguments in the support of assertions that are quite simply unsupported by the evidences (eg "Evidence for ET is mounting daily"). The word doesn't cause "bristling," the repeated and continuing context of its misusage and misapplication can, however, have that effect on some people.

[Jeff Root]

The meaning of the term "consistent with" in general seems very clear,
and I haven't noticed it being misused in this thread. The surprising thing
is that its use here has been criticized.

While the title of the thread could have been better worded, its meaning
is clear, too, and the reason for the second clause is perfectly clear.
I agree with the title, as I said back in post # one-hundred-something.
There is more and more evidence, perhaps not mounting literally every
day, but frequently, which supports the idea that ETs can be out there.
That is evidence *for* ETs. On the other hand, as far as I know,
we don't yet have any evidence *of* ETs, which is what the second
clause states, as a warning not to misinterpret the first clause.

-- Jeff, in Minneapolis

.

[Paul Beardsley]

What Jeff said.

[Paul Wally]

I don't see what the big deal is here anyway. If the current evidence is not conclusive, then that means that we cannot yet conclude that we have evidence of ET.
In any case, if such conclusive evidence is eventually found, does the process by which we arrived at that evidence really matter? I think not. It doesn't matter whether we take a random guess, theorize, speculate (unfounded or founded) or flip a coin in order to discover conclusive evidence of ET. So what is needed in order to discover ET is a powerful heuristic, and this does not necessarily include having a correct theory of ET beforehand.

[eburacum45]

Big difference between the range of conditions life can adapt to given time and exploitable energy to take advantage of, and the range of conditions suitable for the formation of life. Finding life in a large range of habitats says very little about where we might expect life to form, and that is much more important than conditions which we may think or can demonstrate that life can adapt to.

Also true, but we can't be certain what conditions were suitable for the formation of life, so we can't say much about the locations where it might be expected to emerge. Although we may assume with some confidence that abiogenesis occured on this planet at some point in the distant past, there are some who think it may have occured elsewhere, and life was subsequently transferred to Earth from that location.

Possible locations for abiogenesis include Mars, Venus, Ceres, Europa, Titan, Enceladus... the list goes on, with decreasing amounts of probability in each case.

As I've said elsewhere on this forum, ballistic panspermia is unlikely (some might say very unlikely, and I wouldn't disagree), but it is not against the mainstream. Something can be both unlikely and mainstream.

[Colin Robinson]

I just want to add this, then I think I'm more or less done with this topic again.

Observation: Methane on Mars...
a) Hypothesis: ...indicates life.
b) Hypothesis: ...indicates volcanic activity.
c) Hypothesis: ...indicates "recently" exposed methane ice.
d) Hypothesis: ...indicates some other phenomenon we haven't observed yet.

While the highly improbable but highly desirable Hypothesis A would be the ultimate in discoveries, it in no way diminishes the importance and "Wanna know right now; when does the probe get there? Get it there faster, NASA!" factor of all three other possibilities.

Just sayin'.

For anyone who doesn't already know this, ESA and NASA are working together on a mission to Mars involving an orbiter, a lander, and a rover or two, whose objectives include tracking the methane and investigating its source. The project is called ExoMars, and is scheduled for 2016 - 2018.

[Trakar]

Also true, but we can't be certain what conditions were suitable for the formation of life, so we can't say much about the locations where it might be expected to emerge. Although we may assume with some confidence that abiogenesis occured on this planet at some point in the distant past, there are some who think it may have occured elsewhere, and life was subsequently transferred to Earth from that location.

Possible locations for abiogenesis include Mars, Venus, Ceres, Europa, Titan, Enceladus... the list goes on, with decreasing amounts of probability in each case.

As I've said elsewhere on this forum, ballistic panspermia is unlikely (some might say very unlikely, and I wouldn't disagree), but it is not against the mainstream. Something can be both unlikely and mainstream.

well beyond 2 standard deviations, IMO.

[Trakar]

I don't see what the big deal is here anyway. If the current evidence is not conclusive, then that means that we cannot yet conclude that we have evidence of ET.
In any case, if such conclusive evidence is eventually found, does the process by which we arrived at that evidence really matter? I think not. It doesn't matter whether we take a random guess, theorize, speculate (unfounded or founded) or flip a coin in order to discover conclusive evidence of ET. So what is needed in order to discover ET is a powerful heuristic, and this does not necessarily include having a correct theory of ET beforehand.

You well illustrate my point.

[Paul Beardsley]

I'd disagree with what you determine to be "clear," especially when the users of the language seem to be insisting on casual understandings and interpretations rather than employing stricter, and more proper scientific qualifications, only begrudgingly acknowledge the range of actual science evidences when dragged to them, and then use such casually misstated arguments in the support of assertions that are quite simply unsupported by the evidences (eg "Evidence for ET is mounting daily"). The word doesn't cause "bristling," the repeated and continuing context of its misusage and misapplication can, however, have that effect on some people.

This may have been true at the beginning of the thread, but the recent posts by Paul Wally, Colin Robinson and myself have shown appropriate caution.

As Jeff pointed out, the real eyebrow-raiser is the criticism of the expression "consistent with". (No, Jeff didn't refer to it as an eyebrow-raiser, but my phrasing is consistent with what he said.)

There seems to be a "skepticaller than thou" attitude in certain quarters. Evidence doesn't have to be conclusive to serve as a lead. If police find fingerprints on a murder weapon, they interview the suspect. They do not have to present alternative explanations for how come the fingerprints came to be there, any more than they have to present non-life explanations for methane on Mars. The fingerprints don't necessarily mean the suspect is the murderer, but they don't ignore it just because there might be another reason for them being there.

[Paul Wally]

You well illustrate my point.

This can be ambiguously interpreted. Either, I've now said something that you finally agree with or it confirms what you have been saying the whole time. I'll assume the latter interpretation as the more likely one.

I think that you think that the process matters as far as conclusive evidence is concerned. You think that, working on a certain unproven assumption somehow biases the result, but I don't see how that can possibly happen with conclusive evidence of the existence of something. We don't create evidence, we discover it. I see nothing wrong in saying what if there is life under such and such conditions and then carrying on with that assumption as if true with the eventual aim of checking whether in fact it is true. The whole point of making unproven assumption is not to believe it, but in fact, to test whether or not it is true.

I hope this makes things clearer.

[Colin Robinson]

I do. See how it would change us, I mean.

Think back... The (widespread) knowledge that the sky isn't an overturned bowl changed us forever. The repeated discoveries that we're not really the center of anything in time and space, except our own ignorance, helped bring about radical and progressive changes in how we think about ourselves and how we interact with the world. Changes that were invariably met with a great deal of kicking, screaming, upheaval and death (both real and threatened). A very large fraction of the world's population is wailing incessantly over the notion that we've distant common ancestry with every other critter on the planet. We're still choking on the notion that we've common ancestry with ourselves.

If scientific discoveries have not changed us, why all the fuss?

No, our science is dragging us into the future by the scruffs of our necks, sweeping along the unwilling with each next discovery that reveal how we're a much smaller player in a much _much_ larger universe than we've ever imagined possible. This is necessary, if uncomfortable and humbling, and ultimately the very best thing for us.

Well said!

... I just think it's important to let the science educate us in its time, and not anticipate its revelations.

I agree it is important not to jump to conclusions – either positive (e.g. life on Mars) or negative (e.g. no life on Mars)...

[WayneFrancis]

Regarding the emotional aspect, I think a lot of people share my stance: I really, really want there to be life out there, and I really want to know for certain that there is life out there. However, above all else I want the truth, even if it isn't the truth I hoped for. I don't want to pretend that something is evidence when it is not. I will not grasp at straws!

I actually feel hatred for the sort of UFO proponent who deliberately mischaracterises skeptics such as myself as being closed-minded and opposed to the idea of there being life. We are not in denial; when real evidence is found, it will be impossible to deny.

C

[Paul Beardsley]

C

?

[astromark]

Properly qualified remarks are rarely misunderstood or misinterpreted.

Oh my word... have you seen what I see...? and I see it so often. Its alarming..

We have a cor um of agreement here.

That as no such trace has yet been confirmed as real no such conclusion is possible..

That is not based on a belief structure but real and active science.

any other point is less than science. So for me is less than true. Awaiting confirmation.

[IsaacKuo]

?

If you have the font "Wingdings" on your computer, and if your web browser is set to allow the web page to choose its own fonts, then this "C" looks like a thumbs up symbol. If not, then it looks like a capital "C".

[Paul Beardsley]

Thanks for the explanation, Isaac.

And thanks for the thumbs up, Wayne, even if it was just a big C on my machine!

[Trakar]

This can be ambiguously interpreted. Either, I've now said something that you finally agree with or it confirms what you have been saying the whole time. I'll assume the latter interpretation as the more likely one.

I think that you think that the process matters as far as conclusive evidence is concerned. You think that, working on a certain unproven assumption somehow biases the result, but I don't see how that can possibly happen with conclusive evidence of the existence of something. We don't create evidence, we discover it. I see nothing wrong in saying what if there is life under such and such conditions and then carrying on with that assumption as if true with the eventual aim of checking whether in fact it is true. The whole point of making unproven assumption is not to believe it, but in fact, to test whether or not it is true.

I hope this makes things clearer.

Process not only can bias results, it is corruption of the processes of science that spawn pseudoscience,...or perhaps more appropriately, it is the hallmark of pseudoscience to twist and distort the processes of science to derive predetermined results based upon predillection rather than being led to understandings and theories by the verifieable evidences. When people begin shunning the processes of science and attempting to broaden the discussion to encourage more speculative possibilities rather than limiting themselves to the proper scientific definitions and evidences, then we have to be extremely vigilant not to leave mainstream science behind and skip across the boundary into fiction.

[Trakar]

Well said!

I agree it is important not to jump to conclusions – either positive (e.g. life on Mars) or negative (e.g. no life on Mars)...

What is the reasonable default condition? No apparent life, or, abundant hidden life?

[IsaacKuo]

What is the reasonable default condition? No apparent life, or, abundant hidden life?

Right now, we lack sufficient data to form a reasonable default condition. The problem has to do with liquid water conditions. EVERY place we have looked which has liquid water conditions has had life. But if Mars has liquid water conditions, those conditions are far enough underground that they are indeed hidden from us--so far. None of our probes have had to do more than literally scratch the surface.

There have been numerous environments in Earth where we thought life was impossible, but it has turned out to exist in all of the ones with liquid water conditions anyway. Since life on Earth seems to exist everywhere that liquid water conditions exist, it would be very interesting to finally explore somewhere outside of Earth with liquid water conditions. That first exploration may be some sort of digger that explores deep into Mars, or Europa, or some other planet/moon. Or it might be careful study of rocks or ice which displayed firm evidence of having recently been in liquid water conditions (a short enough time so we could reasonably find the remains of soft creatures).

Until that first data, we are in a situation where it's presumptive to have a default condition. We simply have too little data.

[Trakar]

Right now, we lack sufficient data to form a reasonable default condition. The problem has to do with liquid water conditions. EVERY place we have looked which has liquid water conditions has had life. But if Mars has liquid water conditions, those conditions are far enough underground that they are indeed hidden from us--so far. None of our probes have had to do more than literally scratch the surface.

There have been numerous environments in Earth where we thought life was impossible, but it has turned out to exist in all of the ones with liquid water conditions anyway. Since life on Earth seems to exist everywhere that liquid water conditions exist, it would be very interesting to finally explore somewhere outside of Earth with liquid water conditions. That first exploration may be some sort of digger that explores deep into Mars, or Europa, or some other planet/moon. Or it might be careful study of rocks or ice which displayed firm evidence of having recently been in liquid water conditions (a short enough time so we could reasonably find the remains of soft creatures).

Until that first data, we are in a situation where it's presumptive to have a default condition. We simply have too little data.

Observations and evidence determine default

We observe and see no evidence of life on Mars, that is the reasonable default condition.

The default might be incorrect and that is a situation which would demand correction if there is evidence to indicate otherwise.

I have sealed containers of deionized water that contain no apparent or detectable life sitting on my desk, your proposal that everywhere we find liquid water, we find life, would seem to require some adjusting.

[IsaacKuo]

We observe and see no evidence of life on Mars, that is the reasonable default condition.

Based on what we know, our observations are just as consistent that there is life on Mars. It's not enough for you to present one explanation and say this must therefore be the default explanation. You must compare it to other explanations and see if your explanation is a BETTER explanation.

Right now, based on what we know, it's an even balance of lack of information.

I have sealed containers of deionized water that contain no apparent or detectable life sitting on my desk, your proposal that everywhere we find liquid water, we find life, would seem to require some adjusting.

Certainly it's possible to kill natural life to create an artificial "environment", but we do not expect by default that someone has sterilized Mars.

Suppose I tell you that I have a glass of water on my desk. Do you think there is life in that glass of water? You have not detected any life in this glass of water. Should your default assumption be that there is no life in it?

Suppose I give you more data--suppose I tell you that I have looked at this glass of water very closely, and I don't see any signs of life. Okay, maybe my eyesight isn't good enough to see microscopic life forms (if microscopic life forms exist), but surely this is strong evidence that there is no life in that glass of water! Right?

[Paul Wally]

Process not only can bias results, it is corruption of the processes of science that spawn pseudoscience,...or perhaps more appropriately, it is the hallmark of pseudoscience to twist and distort the processes of science to derive predetermined results based upon predillection rather than being led to understandings and theories by the verifieable evidences. When people begin shunning the processes of science and attempting to broaden the discussion to encourage more speculative possibilities rather than limiting themselves to the proper scientific definitions and evidences, then we have to be extremely vigilant not to leave mainstream science behind and skip across the boundary into fiction.

This sounds like a rather general dogmatic creed about what you believe science should be, without giving any examples nor providing any rational argument for it. Please describe a scenario where conclusive evidence can be a biased result. It really looks like a logical impossibility to me. It's like saying if Opportunity observes lifeforms with it's micro-imager, then it's a biased result because they speculated that there is life on Mars before having the evidence. If evidence is as theory laden as you imply, not only would evidence stand on very shaky ground, the word "discover" loses all it's meaning. That's why I'm saying it doesn't matter what you believe, speculate, theorize or guess beforehand, whatever you discover will be the judge of whether your hypothesis is true.

And I think you misunderstand the concept of verifiability . As far as logical positivism goes, the concept of verifiability applies to propositions (theoretical statements). "There is life on the Moon" is a verifiable proposition, because we can go and verify empirically whether in fact it is true. "There is a reality beyond what we can measure" is not a verifiable proposition, according to logical positivism. If something is verifiable then it is merely potentially verified, so "verifiable evidences" reads "potentially verified evidences". All evidences are verified, if it's not verified then it's not yet evidence.

[Colin Robinson]

What is the reasonable default condition? No apparent life, or, abundant hidden life?

If by "apparent life" you mean macroscopic life, then I'd agree it is reasonable to conclude Mars doesn't have that. If there were forests or cities there, we would have detected them. (Unless they were in the "invisible elf" category!)

Microscopic life is another question.

The possibility that a planet might lack macroscopic life, but nonetheless have micro-organisms, is not science fiction but mainstream science. The Earth itself seems to have been like that for several billion years -- most of its history.

Detecting microscopic organisms presents a challenge, not because they are hidden, or invisible, but just because they are small.

All the same , there are several feasible strategies for finding them, if they are either there now, or have been in the past. One strategy has been mentioned by Isaac Kuo -- follow the water.

Since life on Earth seems to exist everywhere that liquid water conditions exist, it would be very interesting to finally explore somewhere outside of Earth with liquid water conditions. That first exploration may be some sort of digger that explores deep into Mars, or Europa, or some other planet/moon. Or it might be careful study of rocks or ice which displayed firm evidence of having recently been in liquid water conditions (a short enough time so we could reasonably find the remains of soft creatures).

Another strategy for finding micro-organisms is to track down stuff that may have been produced by them -- e.g. follow the methane. As ExoMars is intended to do.

Another strategy is to look for the stuff microbes are made of -- follow the complex organic molecules.

I know Viking tried to do that, but it is no longer considered to have produced a reliable negative result. Next year the Curiosity rover will have another go at looking for organics.

Until Mars has been thoroughly investigated using strategies like these, I agree with Isaac.

It is simply too early to talk about a default position re small living organisms on Mars.

[Trakar]

If by "apparent life" you mean macroscopic life, then I'd agree it is reasonable to conclude Mars doesn't have that. If there were forests or cities there, we would have detected them. (Unless they were in the "invisible elf" category!)

Microscopic life is another question...

Not at all, microscopic life on the earth is still one of life's most apparent expressions. The life that has existed for billions of years, early on significantly and obviously altered the chemistries and compositions of our planet's atmosphere and surface layers.

Ambiguous methane wisps notwithstanding, Mars offers nothing suggestive of billions of years of evolutionary adaptation of a proliferate expression of life as we know it, which is arguably a chief characteristic of life as we know it,...obvious and aggressive expansion and adaptation into any and all available niches of energy exploitation. It may turn out that there are deep rock organisms eeking out an existence somewhere in the Martian lithosphere, but the existence of such, currently, isn't much more dependable or verifiable than the transparent Kiblerites you mention.

[Paul Wally]

It may turn out that there are deep rock organisms eeking out an existence somewhere in the Martian lithosphere, but the existence of such, currently, isn't much more dependable or verifiable than the transparent Kiblerites you mention.

Of course it's not dependable, because we cannot depend on what has not been observed, but it is definitely verifiable. An invisible (Martian) elf is an example of something that is not verifiable. Visible elves on the other hand are verifiable. They're just not verified. There's a difference between "verifiable" and "verified".

[iquestor]

Not at all, microscopic life on the earth is still one of life's most apparent expressions. The life that has existed for billions of years, early on significantly and obviously altered the chemistries and compositions of our planet's atmosphere and surface layers.

Ambiguous methane wisps notwithstanding, Mars offers nothing suggestive of billions of years of evolutionary adaptation of a proliferate expression of life as we know it, which is arguably a chief characteristic of life as we know it,...obvious and aggressive expansion and adaptation into any and all available niches of energy exploitation. It may turn out that there are deep rock organisms eeking out an existence somewhere in the Martian lithosphere, but the existence of such, currently, isn't much more dependable or verifiable than the transparent Kiblerites you mention.

Actually many scientist beleive that life here on earth started as a deep biosphere, using geothermal heat and chemical energy first, then later moved to the surface. I think its possible there is a deep biosphere on mars we havent detected, except through those methane 'wisps'....

[Trakar]

Actually many scientist beleive that life here on earth started as a deep biosphere, using geothermal heat and chemical energy first, then later moved to the surface. I think its possible there is a deep biosphere on mars we havent detected, except through those methane 'wisps'....

I find no compelling reason to believe Martian methane to be biogenic in origin.

"Geology of possible Martian methane source regions" -
http://www.sciencedirect.com/science...32063310001443

"Methane on Mars: A Perspective from Earth"
http://www.searchanddiscovery.com/ab..._schoell02.pdf

[Colin Robinson]

Not at all, microscopic life on the earth is still one of life's most apparent expressions. The life that has existed for billions of years, early on significantly and obviously altered the chemistries and compositions of our planet's atmosphere and surface layers.

What was so obvious about the way early microscopic life altered our planet's chemistry?

Earlier in this thread, you mentioned the free oxygen in Earth's atmosphere.

The sustained high level of free oxygen is a strong biosignature, probably the most compelling argument for life on our planet from afar.

However, as I understand it, oxygen first started to build up in the atmosphere about 2.4 billion years ago -- about 1 billion years after life got started. Is that what you call "early on"?

Before that, oxygen was already being produced, but it was reacting with elements such as iron to form oxides. So, yes, there were changes to the chemistry of surface layers.

But is the presence of iron oxides on a planetary surface an obvious sign of life?

[R.A.F.]

...is the presence of iron oxides on a planetary surface an obvious sign of life?

Is there a reason why it would be?

[Colin Robinson]

Why would it be?

Because Trakar just told us that the chemical manifestations of microscopic life here on Earth were both early and obvious…