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This is all very interesting, Gary, but please
note that I've never argued that the current evidence for water chemistry is
flawed. I have no trouble with the conclusions arrived at so far about
water chemistry. And it's good to know that sediment can't form in CO2 (or
that, if it does, it's not common knowledge how it could - I'm not sure what's
been done in finding analogous processes, given how unlikely they might have
seemed until now.)
However, nothing you've said addresses my main
question: how does any of this evidence for water chemistry preclude formation
of larger-scale features on Mars through CO2 phase changes? Your ability
to tell me what's in a high school chemistry refresher is evidence
only that you have some time on your hands. The fact that you haven't
addressed the above question (repeated here for what may be the third time, in a
different form) tells me either that you haven't been reading (in which case,
why reply?) or that you're evading the question.
Hoffman's website carries the provocative
banner of Mars Without Water. By this, he doesn't mean "Mars has no
water." For one thing, the poles and the traces of water vapor in the
atmosphere are established facts - if he were saying "Mars has no water", he'd
be a total crank. Given, however, that he talks about small amounts
of water and the role that these amounts might play in White Mars (necessarily
almost negligible, given his thesis), you can't pin the crank label on
him. At least, not on that basis.
What he means is "Plausible Explanations for
Apparent Martian Hydrology that Don't Require Hydrology." No points for
diplomacy on his part, of course, but otherwise he's doing the right thing for
garnering attention. And the more that he's misinterpreted by people who
should know better, and who could think better, the more his provocation works
for him. He gets to point out that certain people are
engaged very superficial readings of his thesis, and only making themselves
look lazy, incompetent, or both.
If you want to make real progress against
White Mars, you have to do it in terms at least as scientific as Hoffman himself
- ideally, better. Off-the-point recitations from high school chemistry,
as if they were some killer blow, amount to shooting yourself in the foot -
precisely what he wants you to do.
-michael turner
----- Original Message -----
Sent: Sunday, March 28, 2004 2:59
PM
Subject: Re: Standing Body of Water
Left Its Mark in Mars Rocks
Michael,
OK, since you asked, sit down and I will give you a mini-lecture on
molecular chemistry. The evidence for water is the salts. I have
it from a particular Mars planetary scientist (pers. comm. on Thursday) that
the now-famous "blueberries" are mostly hematite (Fe3O4--its false color,
folks), and that the matrix material that the "blueberries" rest upon and are
incorporated within, has lots of magnesium sulfate (MgSO4) a.k.a. Epsom salt,
in it.
Water is a polar molecule with amazing solvent properties. It is
polar because the two hydrogen atoms are mostly on one side, at about 105
degrees separation. That side therefore has a slightly positive
charge. Conversely, the oxygen side of the molecule is slightly negative
in charge. This is because the electrons in their clouds spend slightly
more of their time on the oxygen side, and less upon the hydrogen-bonded
sides. The polarity of water makes it able to pluck surface cations from
rocks and, importantly, hold them in solution. This polarity causes
water molecules to surround cations (and, flipping the molecule around,
anions) and gives water other amazing properties (increased heat capacity,
freezing and boiling point suppression), because it has structure.
Carbon dioxide is not polar. Its molecular structure is a linear
0-C-0. Liquid CO2 cannot therefore do the feats listed above for liquid
water, among them pluck and hold ionic salts in solution, to later precipitate
upon evaporation in sediments and make salt-saturated rocks like those
recently found on Mars.
Gary
Gary, among the staunch Martian water
advocates, you've made what I think is
the best contribution to the
debate so far. This contribution is the phrase
"satisfactorily
uncomfortable." That's got my vote for Oxymoron of the
Month.
And it's quite a bit funnier than Eugene Leitl's non sequitur,
"Faith =
absence of data."
>From what I can see, all we have is
this:
(1) there is solid evidence of water
chemistry
(2) there is persuasive evidence of liquid movement on
the surface
Where is the evidence that the water chemistry stems from
the same liquid
that moved on the surface, meaning that this liquid was
certainly almost
entirely water?
For your sake, I interpret the
following as a Freudian slip, but as a wry
joke:
> BTW, us
scientists do solicit funding, but most try to not let the
> facts get
in the way.
As for this:
> you and others on this list
(Eugen, Jim, et al.) have made it obvious
> [liquid CO2] too much of a
long shot.
... well, "too much of long shot" is everyday English for
"neglibly
probable." Certain pundits' rantings notwithstanding,
probability is a
measure of belief. "Frequentist" arguments are
still fundamentally this
Bayesian measure, since probability and
statistics have been intelligently
co-designed for agreement at the limit
of statistical observation. Do we
have enough data for a "frequentist"
probability assessment about liquid CO2
flows on Mars? I haven't
seen it. So we're back to probability as a
measure of belief.
And that takes us back to theory, still far
from
complete.
>From dozens of casual observations, it's pretty
easy to build a frequentist
case for the intuitively obvious proposition
"heavier things fall faster."
Ancient Greek ballisticians (a smarter
bunch than people realized until
recently) must certainly have known that
this wasn't true, but probably
shrugged off the popular misconception,
because their jobs were safe as long
as there were imperious Romans,
bloodthirsty pirates, and other Greeks
willing to go to war with the
ballisticians' city-states. Just as people in
Columbus' time who
knew better could shrug off the superstition that the
earth was
flat. Any ship's captain who made an issue of it wasn't going
to
get a good navigator, and that ship would be increasingly unlikely to
make
it back to port. Evolution in action.
But we're dealing
with evidence of water on Mars here, where it's extremely
expensive and time-consuming to make even a
handful of the required
observations, and in a context whose political
economy is a very different
kettle of fish than the one from which Greek
ballisticians and 15th century
navigators ladled out such nourishing
broth. Gary, can you tell me for sure
that you know that there have
been enough of the right kinds of observations
to make an assessment of
liquid CO2 flows on Mars as being *neglibly*
probable? Until I see
evidence of such observations, I would tend to go
with (literal) weight
of evidence: there is a huge amount of CO2 on Mars,
but apart from the
polar caps, the only evidence of water on other parts of
the surface has
been derived from subtle chemical experiments by probes that
can cover
only a small amount of that surface.
-michael
turner
[EMAIL PROTECTED]
----- Original Message -----
From:
"Gary McMurtry" <[EMAIL PROTECTED]>
To:
<[EMAIL PROTECTED]>
Sent: Sunday, March 28, 2004 3:32 AM
Subject:
Re: Standing Body of Water Left Its Mark in Mars
Rocks
>
> Michael,
>
> First, may I suggest
a better question to bat about may be "if there
> is now mounting
evidence for abundant liquid water once on Mars,
> where did it go and
why?". I appreciate your pursuit of a competing
> hypothesis for
liquid CO2, because I think in trying to suggest it,
> you and others
on this list (Eugen, Jim, et al.) have made it obvious
> it's too much
of a long shot.
>
> BTW, us scientists do solicit funding, but
most try to not let the
> facts get in the way. Most of our
funding awards are peer reviewed,
> which although an imperfect and
increasingly overtaxed process, still
> functions to weed out the
crud. As you probably know, unlike
> religion, science is
self-correcting and evolves through time. We
> are
satisfactorily uncomfortable with our present knowledge
state.
>
> Gary
>
> >--- Michael Turner
<[EMAIL PROTECTED]> wrote:
> >
> >>
>
>> So I'm still holding out for a possible CO2
>
>> sea/ocean/lake as an explanation
> >> for
features that we, on our water planet, associate
> >> only
with bodies of
> >> water. That doesn't mean that
there haven't *also*
> >> been bodies of water on
>
>> Mars, just that it doesn't look like the case is
>
>> closed yet. Unless I've
> >> missed
something.
> >>
> >> -michael turner
>
>> [EMAIL PROTECTED]
> >>
> >>
>
>>
> >> ==
> >> You are subscribed
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>>
> >As I understand it, the recent findings by the
rovers
> >indicate deposits of gypsum and salt, which
dissolve
> >in water, but not in supercritical CO2
>
>
> >=====
> >
> >Sincerely
>
>
> >
> >
> >James McEnanly
>
>
> >
> >__________________________________
>
>Do you Yahoo!?
> >Yahoo! Finance Tax Center - File online. File
on time.
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>
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