Leading Horses to Water
Ancient Greeks began the way of
thinking originally known as natural philosophy but which we now call
science. Science emerged as we know it during the Renaissance, in
an age dominated by fear, superstition, injustice, and brutality.
In other words, pretty much like the present. These musings are
aimed at explaining how science works, and how science can serve even
nonscientists in their efforts to make sense of the world. I can
try to explain things but it’s up to you to decide whether or not you
wish to drink from these waters.
#21 - Mars Rovers
American Heathen: aired: 22 September 2012
The recent successful landing of another Mars rover, Curiosity, in
August of this year has been a source of national pride for an
embattled national space exploration program here in the USA. The
challenges associated with just getting the rover onto Mars, to say
nothing of what may be encountered during its multi-year missions, are
daunting.
In the times before missions to Mars began to provide empirical data by
which scientific speculation could be validated, various ideas existed
about what Mars would be like. Many of those ideas proved to be
grotesquely, even laughably wrong. When the human mind is
unfettered by the need to be consistent with evidence, it can go
anywhere it chooses. There are many logical possibilities, and
even more possibilities that are illogical, but it’s not possible to
choose among those ideas without evidence. Without evidence, all
we have is logic if we are to make a rational choice, but what is
logically plausible may still be far from reality.
As an example of this, in the era before spacecraft were sent to Mars,
it was suggested by some planetary scientists that the air pressure on
the surface of Mars was about 50 mb. By way of comparison, the
air pressure on the surface of the Earth is about 1000 mb. A
pressure of 50 mb corresponds to the pressure at a height of about 22
km (more than 12 miles up!) above the Earth’s surface. I remember
seeing a scientific paper that proposed this value of about 50 mb,
based on some evidence obtained not directly from Mars but by
measurements done here on Earth. The analysis of the data
included a statistical test of the validity of the calculation, and it
offered a relatively high probability that the value of about 50 mb was
in the ballpark, so to speak.
Some years later, the first measurements directly from Mars showed that
the actual surface pressure was much less than 50 mb - more like 5
mb. That pressure value corresponds to a height of about 35 km
above the Earth (more than 20 miles). How could those scientists
have been so wrong? Well, this sort of thing happens all the time
when we have no data by which to test our ideas. Science is all
about the data – logic is necessarily involved but it plays a lesser
role.
Not only is the atmosphere of Mars very thin compared to that here on
Earth, but the gases that make up that atmosphere are mostly carbon
dioxide, with only a very tiny amount of oxygen. Even if the
pressure could be increased, the Mars atmosphere wouldn’t sustain human
life. Like all the rest of the planets in our Solar System except
Earth, Mars is pretty hostile to humans, although it’s probably the
least hostile of them. Nevertheless, an exciting motivation for
the exploration of Mars is the possibility of finding evidence of life
on Mars. If not actual life, there may be evidence of the
existence of life from a time when the surface of Mars was not so
hostile to Earth-like life. The issue is a very important one for
us humans – are we the only planet with life in the vast volumes of the
Universe? If, as science now reveals, planets are abundant in the
universe, the chances of life forming elsewhere may be relatively
high. The existence of extraterrestrial life is an important
question for humans, not just because of the scientific interest, but
also for our ability to understand our place in the universe.
We once thought that we were the center of the universe. Science
has shown the planets we can see easily don’t revolve around us, as it
was once thought, but revolve around the sun, as does the Earth.
And our sun is a more or less ordinary star in one of the arms of a
vast galaxy of billions of stars (the Milky Way). And the Milky
Way Galaxy is but one of billions of galaxies we can see in our
advanced telescopes. Our physical position in the universe
is comparable to a mote of bluish dust floating in the atmosphere of
the Earth. Could it truly be that the incomprehensible vastness
of the Universe is devoid of life, but for us? Do we still
qualify as something absolutely unique in the Universe, or are we but
one among many living creatures in a Universe teeming and pulsating
with life?
These are indeed important questions to us humans. Science has
shown us that many of the myths conjured up in the scriptures of
religion simply are not true. But scientific predictions of the
nature of the Universe are not settled by consulting some authoritative
ancient book. They’re tested against empirical observations –
evidence that can be used to evaluate how good our ideas are, and how
they may need modification to fit the evidence. We don’t change
the evidence to fit the idea – we change the idea to fit the
evidence! When new evidence comes in, it’s likely that our ideas
will change again and again. Every time we explore a planet for
the first time, scientists are surprised by the new data!
Just imagine – we now have machines rolling about on the surface of
Mars, designed to provide us with new evidence about Mars and its
history. On the surface of Mars!! To our naked eyes, Mars
is but a tiny pale orange dot in our night sky. It takes many
months to get there on what seems to us to be a fairly speedy
spacecraft. It takes a speed of about 11 km/s (or about 25,000
mph) just to escape the Earth’s gravity! Distances in space are
nearly incomprehensibly large! It takes about 8 minutes for light
to travel from Mars to the Earth! And now our far-away machines will be
giving us new insights by which our concepts of Mars once again will be
changing.
The cost of sending the Mars Science Laboratory (aka the Curiosity
rover) to Mars was about $2.5 billion. According to one Website,
the Catholic Church had an estimated annual income of more than $400
billion in the year 2000. If we consider that the Catholic Church
has been an impediment to science over most of its long history, with
its doctrines about our place in the Universe mired in stagnation for
nearly 2 thousand years, it seems to me that we’re getting a huge
return in terms of knowledge and insight from the relatively modest
cost of the Mars Science Laboratory, especially when compared to what
it takes to operate the single largest christian denomination for one
year. What new insights has the church given us? Another
comparison – a Nimitz-class aircraft carrier costs about $4.5 billion,
somewhat less than twice the cost of the MSL. The National
Football league generates annual revenues of about $9.5 billion –
almost four times the cost of the MSL.
Our newest Mars rover is a tribute to that very human spirit of seeking
knowledge and understanding, rather than accepting mythology as sacred
truth, and scriptures as evidence. The rover is a shining symbol
of human aspirations to learn our true place in the Universe, without
prejudice or fear of what the answer might be. We are made of
star debris, and our ancestry therefore goes back a long way, but only
relatively recently have we begun to seek fearlessly and resolutely
some credible answers to our questions.
Science
is not a religion but rather a tool for those who wish to think for
themselves about the natural world. Its primary characteristic is
its willingness to entertain questions from those who wish to obtain
believable answers.