reply to post by Skyfloating
A few thoughts:
While it is a nearly universally accepted opinion that there's ZERO doubt of extensive water having once existed on Mars --- the timescale is the bit
that's still open to great question.
Consider the extremely TINY amount of time that man has existed on Earth....and especially civilization, and the 'luxury' that that afforded to
contemplate things other than being eaten by Sabretooth Tigers....and our sliver of time shrinks. In comparison to the over-all timescales of the
Think of it this way: If you take the rise of one of the earliest precursor hominids that eventually led to us
, and their earliest appearance
in the fossil record, and plot it on an imaginary scale of one "Earth year" (twelve months), then those "ancestors" appeared on 1st January.
man didn't develop until sometime around 28th-29th December, in that comparison. AND, civilization and ultimately, the
technology we now take for granted? 31st December....at about 11:00 PM (23:00). (Those are approximaitons, of course, for illustrative purposes).
(There is a way to compare the ENTIRE Earth's history (and the Solar System) in a similalarly, to get a sense of that
(I can try to Google around for it....)
SO, point being, it is conceivable that the four inner, "rocky" planets (exception possibly for Mercury, due to its proximity to the Sun) followed
essentially the same paths of formation, and evolution, at least for hte fist (X) billion years. The exact amount of time is unknown, of course....we
are best familiar with our home, and have to infer from that.
What it stems down to, RE: Mars, is How long
did sufficient atmosphere, and thus pressure, exist to allow liquid water to remain liquid
on the surface??
did conditions change to those that are observed and measured today?
I personally have little doubt that, given atmosphere/liquid water, that life DID begin, much in the same way it did here.
But, that process ---- from earliest, most basic single-celled lifeforms, to very complex multi-cellular organisms seems to require a great deal of
time to come about. Again, based on our knowledge and history on Earth.
Since, deep deep down at its most basic sense, all life is really just chemistry
at work, it is subject to the same laws of physics, and
atoms' interactions that underlies all of chemistry. And this is got to be universal, in our "realm" at least. So timescales of life's
development patterns must be roughly similar, everywhere we look in our Universe.