PROBABILITY OF A LIVING PLANET
(Investigator 194, 2020 September)
|As of 23 July 2020, there are 4,197 confirmed
exoplanets, the majority of which were discovered by the Kepler space
telescope. There are an additional 2,418 potential exoplanets from
Kepler's first mission yet to be confirmed, as well as 889 from its
"Second Light" mission and 1,288 from the Transiting Exoplanet Survey
Satellite (TESS) mission.
NUMBER OF PLANETS
Our Solar System has eight planets. Pluto, discovered in 1930, was
considered the ninth but is no longer regarded as a planet. In the
1990s exoplanets — planets of other suns or stars outside of our Solar
System — began to be discovered, and currently number about 4200.
Of the 4200 exoplanets so far discovered Wikipedia
lists 48 in the "habitable zone". This does not mean they're inhabited,
merely that they have some of the necessary preconditions:
habitability is thought to require orbiting at the right distance from
the host star for liquid surface water to be present, in addition to
various geophysical and geodynamical aspects, atmospheric density,
radiation type and intensity, and the host star's plasma environment...
In November 2013, astronomers reported, based on Kepler
space mission data, that there could be as many as 40 billion
Earth-sized planets orbiting in the habitable zones of Sun-like stars
and red dwarfs in the Milky Way, 11 billion of which may be orbiting
Sun-like stars. (Wikipedia)
According to the Bible, it was God's special activity that shaped planet Earth for human habitation.
The Bible gives no indication that "God" intervened on any other planet
to organize it for intelligent life and civilization. It says that
humans are "a little lower than the angels" (Psalms 8:3-5) which may
imply that there is no physical life more advanced than humans.
The question I will investigate is: How
small must the probability that a planet can self-organize itself for
intelligent life and civilization have to be, before we should agree
with the Bible that God did it or at least assisted?
In the 19th century many people believed there is human-like life on Mars.
The idea became popular after Italian astronomer Giovanni Schiaparelli
described straight lines on Mars' surface and in 1877 referred to them
as "canali". This means "channels" or "grooves" but got translated into
English as "canals".
American astronomer Percival Lowell (1855-1916) saw the lines too and
concluded they are constructed canals, which implied that an
intelligent, technological civilization built them. (But some
scientists disagreed and interpreted the "canali" as optical illusions
or areas of vegetation.)
Lee (2018) cites the Los Angeles Times of 1907:
Scientists now declare
that the many lines and spots on Mars represent verdure along a most
wonderful canal system, which the inhabitants of the planet have
constructed for purposes of irrigation.
The canals featured in science fiction literature from the 1890s onwards. Wikipedia under "Martian Canal" lists many novels in which the "canals" are presented as intelligent constructions by Martians.
The UFO phenomenon after 1948 attributed the origin of flying saucers
and aliens to all over the Universe — Mars became only one origin among
many. Shelves of bookshops filled with books about UFOs, and the
Universe began to seem like it's crowded with alien, technological
civilizations. Most famous was Erick von Daniken's Chariots of the Gods.
Some writers even argued for an outer space origin of the human race.
Flindt & Binder (1974) claimed "Earth has been visited more than
5000 times by creatures from other planets" and "The human race may be
an interstellar colony..." Crowley & Pollock (1989) argue that the
Garden of Eden was on Mars and humans emigrated to Earth to survive a
cataclysm that occurred on Mars 40,000 years ago!
With two out of eight known planets, Earth and Mars, believed to be
inhabited by technological civilizations, atheists and evolutionists
could have concluded that the odds of a planet self-organizing itself
for intelligent life from the laws of physics and chemistry without
supernatural assistance, is 2/8 or 25%. Whether anyone made such a
claim I don't know, but it would have been evidence-based.
In 1965 began the era of high-resolution mapping of other planets when
the Mariner 4 space probe sent back pictures of Mars' surface. These
decisively showed there are no canals.
That still left one planet, Earth, with intelligent life and
civilization. The odds of planet Earth having originated solely by the
working of the laws of physics and chemistry without any God could
therefore be construed as 1/8 or 12.5%. If this argument is valid it
implied that 1/8 of all planets should have technological
civilizations. A good many science fiction novelists wrote as if this
is the case — that thousands of planets within reach of Earth support
However, if intelligent workmanship, i.e. God's supernatural
intervention, is necessary to make planets fit for civilization, then
the odds of planets producing civilizations without divine help would
not be 1/8, but zero.
THE PROBABILITY GOES DOWN
In 1961 astronomer Frank Drake proposed the "Drake equation" of seven
factors needed to estimate the number of technological alien
civilizations. The problem is that although several factors can be
estimated such as the number of stars, the others are subjective
guesses — resulting in estimates for the number of alien civilizations
in the Universe other than on Earth as somewhere between billions and
In 1992 astronomers began discovering "exoplanets" i.e. planets outside
our Solar System. Thirty were discovered by 2000 CE. None of them have
been confirmed suitable for human life or even for any biological life.
This reduced the probability of planets being able to self-organize to
support intelligent life to 1 in 38 — or lower since the odds showed a
In January 2012 the number of confirmed alien worlds reached 720 — but
none have been confirmed fit for human life or any life. Some are too
cold, others too hot, too dry, too big with crushing gravity, or lack a
solid surface or stable orbit, or are bathed in lethal radiation with
no ozone layer or magnetic field for protection.
This made the probability, as based on observation 1/720 — or lower since the observed odds are still decreasing.
The current count of discovered planets is about 4200 but with no
indication yet of life on any of them. This makes the probability
1/4200 or lower.
No exoplanets are yet confirmed as fit for human life. Some exoplanets
are called "Earth-like". This does not imply that living things live
there, but merely that the planets are approximately the right size and
a suitable distance from their Sun. This much is also true of Mars,
Venus and the Moon — but all three seem lifeless.
We began with observable odds of 2/8 and are now down to 1/4200.
WILL THE PROBABILITY GO DOWN TO ZERO?
Wikipedia under "List of potentially habitable planets" says:
In November 2013,
astronomers reported, based on Kepler space mission data, that there
could be as many as 40 billion Earth-sized planets orbiting in the
habitable zones of Sun-like stars and red dwarfs in the Milky Way, 11
billion of which may be orbiting Sun-like stars.
Science News, quoting Professor Conselice, reports:
"There should be at
least a few dozen active CETI civilizations in our Galaxy under the
assumption that it takes 5 billion years for intelligent life to form
on other planets, as on Earth," said Professor Christopher Conselice...
Nicola Davis (2020) reports in Astrophysical Journal:
But according to new
calculations there could be more than 30 intelligent civilisations in
our galaxy today capable of communicating with others.
“I think it is extremely important and exciting because
for the first time we really have an estimate for this number of active
intelligent, communicating civilisations that we potentially could
contact and find out there is other life in the universe...” said
Christopher Conselice, a professor of astrophysics at the University of
Nottingham and a co-author of the research.
Paul Davies noted:
In recent years it has
become fashionable to assume that life emerges rather readily under
Earth-like conditions and is therefore likely to be widespread in the
universe. This belief underpins the ambitious astrobiology programmes
of NASA and the European Space Agency, the goal of which is to discover
a second sample of life. (2006)
Davies subsequently authored The Eerie Silence
(2011), discussing the total absence of radio signals of intelligent
origin, or other signs of aliens, and seeking explanations for this
Davies also wrote The Goldilocks Enigma Why Is the Universe Just Right for Life?
(2008) and shows that: "Calculations suggest that even small changes in
some key parameters would wreck familiar structures in the universe and
prevent life from arising."
The anomalous situation therefore is that we have a "Universe Just
Right for Life" but also an "Eerie Silence" as if there is no
technologically advanced life except on Earth.
With the odds of intelligent life as calculated from the number of
lifeless discovered planets going down, down, down, how low must the
odds get before it's reasonable to conclude: "God intervened
supernaturally to prepare Earth for human life?"
NASA's latest planet hunting telescope, the Transiting Exoplanet Survey
Satellite, "should be able to find 20,000 planets of all sizes ranging
from Jupiter-sized planets to planets the size of Earth or even the
size of Mars." (Weule 2018)
If all 20,000 planets turn out lifeless, the calculated odds of
intelligent life arising by natural means would decrease to about 1 in
24,000 or lower.
In astronomy and
astrobiology, the circumstellar habitable zone (CHZ), or simply the
habitable zone, is the range of orbits around a star within which a
planetary surface can support liquid water given sufficient atmospheric
pressure. Note that this does not ensure habitability...
The article mentions planets initially considered habitable but mistakenly so:
• HD 85512b was initially estimated to be potentially habitable, but ... is now considered non-habitable.
• Kepler-69c has gone through a
similar process; though initially estimated to be potentially
habitable, it was quickly realized that the planet is more likely to be
similar to Venus, and is thus no longer considered habitable.
• Similarly, Tau Ceti f was initially
considered potentially habitable, but the improved model of the
circumstellar habitable zone places the planet exterior to the outer
limits of habitability...
• Kepler-438b was also initially
considered potentially habitable ... however, it was later found
to be a subject of powerful flares that can strip a planet of its
atmosphere, so it is now considered non-habitable.
• KOI-1686.01 was also considered a
potentially habitable exoplanet after its detection in 2011, until
proven a false positive by NASA in 2015.
HOW MANY PLANETS?
A rough estimate is that the Universe has 100 billion galaxies and an
average of 100 billion stars per galaxy. With one planet on average
around each star that's a lot of planets — in fact
Regarding the Milky Way galaxy Wikipedia says:
About 1 in 5 Sun-like
stars have an "Earth-sized" planet in the habitable zone. Assuming
there are 200 billion stars in the Milky Way, it can be hypothesized
that there are 11 billion potentially habitable Earth-sized planets in
the Milky Way, rising to 40 billion if planets orbiting the numerous
red dwarfs are included.
These numbers are so big that scientists won't soon confirm the zero
probability — unless they discover general principles, distinct from
discovering and analyzing planets, by which to rule out intelligent
physical life outside our Solar System.
How small must the odds of intelligent, technology-using life
originating entirely naturally on a planet become before it's
reasonable to conclude that Earth became a "living planet" by
Davis, N. (2020)
Davies, P. In Search of a Second Genesis, New Scientist, 11 February, 2006, 48-49
Davies, P. 2008 The Goldilocks Enigma, Mariner Books
Davies, P. 2011 The Eerie Silence, Mariner Books
Haynes, K. February 12, 2020
Lee, K. (2018) https://blog.newspapers.com/mars-canals/
Smith, H.A. Alone in the Universe, American Scientist, July-August 2011, 320-327
Weule, G. (2018)