Up to twenty years ago, a reasonable opinion among scientists was that there might be just one solar system. Ours. Scientists like to project gravitas; having little green men all over didn’t look serious.
However, studying delicately the lights of stars, how they vary, how they doppler-shift, more than 1,000 planets have been found. Solar systems seem ubiquitous. Astronomers reported in 2013 that there could be as many as 40 billion habitable Earth-size planets in the galaxy.
Yes, that’s the center of a galaxy, and it has experienced a galactic size explosion from its central black hole.
One out of every five sun-like stars in our galaxy has a planet the size of Earth circling it in the Goldilocks zone, it seems – not too hot, not too cold – with surface temperatures compatible with liquid water. Yet, we have a monster black hole at the center of our giant galaxy, just like the one exploding above.
The Milky way’s black hole is called Sagittarius A*. It exploded last two million years ago. Early Homo Erectus, down south, saw it. The furious lobes of the explosion are still spreading out, hundreds of thousands of light years away.
We are talking here about explosions potentially stronger than the strongest supernova by many orders of magnitude (depending upon the size of what’s falling into Sagittarius. By the way, a cloud is just heading that way).
Such galactic drama has a potentially impact on the presence of advanced life. The richer the galaxy gets in various feature the situation looks, the harder it looks to compute the probability of advanced life.
The profusion of habitable planets is all the more remarkable, as the primitive methods used so far require the planet to pass between us and its star.
(The research, started on the ground in Europe, expanded with dedicated satellites, the French Corot and NASA’s Kepler spacecraft.). Sun-like stars are “yellow dwarves”. They live ten billion years.
From that, confusing “habitable” and “habitated”, the New York Times deduced: “The known odds of something – or someone – living far, far away from Earth improved beyond astronomers’ boldest dreams on Monday. “
However, it’s not that simple.
Primitive bacterial life is probably frequent. However advanced life (animals) is probably very rare, as many are the potential catastrophes. And one needs billions of years to go from primitive life to animals.
After life forms making oxygen on Earth appeared, the atmosphere went from reducing (full of strong greenhouse methane) to oxidizing (full of oxygen). The greenhouse mostly disappeared. Earth froze, all the way down to the equator:
Yet volcanoes kept on belching CO2 through the ice. That CO2 built up above the ice, caused a strong greenhouse, and the ice melted. Life had survived.
That “snowball Earth” repeated a few times before the Earth oxygen based system became stable. catastrophe engaged, but avoided, just barely.
Many are the other catastrophes we have become aware of, that could wipe out advanced life: proximal supernovas or gamma ray explosions.
Cataclysmic eruption of the central galactic black hole happen frequently. The lobes from the last one are still visible, perpendicularly high off the galactic plane. The radiation is still making the Magellanic Stream simmer, 200,000 light years away. Such explosions have got to have sterilized a good part of the galaxy.
In 2014 when part of the huge gas cloud known as G2 falls into Sagittarius A*, we will learn better how inhospitable the central galaxy is for advanced life.
Many of the star systems revealed out there have susrprising feature: heavy planets (“super Jupiters“) grazing their own stars. It’s unlikely those giants were formed where they are. They probably swept their entire systems, destroying all the rocky planets in their giant way. We don’t understand these cataclysmic dynamics, but they seem frequent.
Solar energy received on Earth fluctuated and changed a lot, maybe from one (long ago) to four (now). But, as it turned out just so that Earthly life could survive. Also the inner nuclear reactor with its convective magma and tectonic plates was able to keep the carbon dioxide up in the air, just so.
The goldilocks zones astronomers presently consider seem to be all too large to allow life to evolve over billions of years. They have to be much narrower and not just with red dwarves (the most frequent and long living stars).
One of our goldilocks, Mars, started well, but lost its CO2 and became too cold. The other goldilocks, Venus, suffered the opposite major technical malfunction: a runaway CO2 greenhouse.
Mars’axis of rotation tilts on the solar system’s plane enormously: by 60 degrees, over millions of years. So Mars experiences considerable climatic variations over the eons, as it goes through slow super winters and super summers.
Earth’s Moon prevents this sort of crazy hyper seasons. While, differently from Venus, Earth rotates at reasonable clip, homogenizing the temperatures. Venus takes 243 days to rotate.
It is startling that, of the four inner and only rocky planets, just one, Earth has a rotation compatible with the long term evolution of advanced life.
Earth has also two striking characteristics: it has a very large moon that store much of the angular momentum of the Earth-Moon system. Without Moon, the Earth would rotate on itself once every 8 hours (after 5 billion years of braking by Solar tides).
The Moon used to hover at least ten times closer than now, when earth’s days were at most 6 hours long.
The tidal force is the difference between gravitational attraction in two closely separated places, so it’s the differential of said attraction (which is proportional to 1/dd; d being the distance). Hence the tidal force is inversely proportional to the cube of the distance.
Thus on early Earth tides a kilometer high were common, washing back and forth every three hours. a hyper super tsunami every three hours, going deep inside the continents. Not exactly conditions you expect all over the universe.
Hence biological material fabricated on the continental margins in shallow pools would get mixed with the oceans readily. That would guarantee accelerated launch of life (and indeed we know life started on Earth very fast).
The theory of formation of the Moon is wobbly (recent detailed computations of the simplest impact theory do not work). All we know for sure, thanks to the Moon rocks from Apollo, is that the Moon is made of Earth mantle materials.
Somehow the two planets fissioned. (Fission. Get it? It maybe a hint.)
Another thing we know for sure is that Earth has, at its core, a giant nuclear fission reactor, keeping Earth’s core hotter than the surface of the sun. An unimaginable liquid ocean of liquid iron deep down inside below our feet undergoes iron weather. Hell itself, the old fashion way, pales in comparison.
Could the Moon and the giant nuclear reactor have the same origin? This is my provocative question of the day. The Moon, our life giver, could well have formed from a giant nuclear explosion, of another of our life givers, the nuke at the core. I can already hear herds of ecologists yelp in the distance. I present the facts, you don’t decide.
All the preceding makes this clear:
Many are the inhabitable planets, yet few will be habitated by serious denizens.
This means that the cosmos is all for our taking. The only question is how to get there. The closest stars in the Proxima, Beta and Alpha Centauri system are not attainable, for a human crew, with existing technology.
However, if we mastered clean colossal energy production, of the order of the entire present energy production of humanity, we could get a colony there (only presently imaginable technology would be fusion).
Giordano Bruno, professor, astronomer, and priest suggested that there were many other habitated systems around the stars. That insult against Islam Christianity was punished the hard way: the Vatican, the famous terrorist organization of god crazies, put a device in Giordano’s mouth that pierced his palate, and having made sure that way that he could not tell the truth, the terrorists then burned him alive. After seven years of torture.
The horror of truth was unbearable to theo-plutocrats.
Now we face something even worse: everywhere out there is very primitive life. It is likely gracing 40 billion worlds. But, if one has to duplicate the succession of miracles and improbabilities that made Earth, to earn advanced life, it may be just here that civilization ever rose to contemplate them.
Congratulations to India for launching yesterday a mission to Mars ostensibly to find out if there is life there (by finding CH4; while life is presently unlikely, Mars has much to teach, including whether it started there). That’s the spirit!
The spirit is to have minds go where even imagination itself did not go before.
If we sit back, and look at the universe we have now, from Dark Matter, to Dark Energy, to Sagittarius, to the nuclear reactor below, to billions of Earths, to a strange Higgs, to Non Aristotelian logic, we see a wealth, an opulence of possibilities unconceived twenty years ago.
Progress is not just about doing better what was done yesterday. It’s also about unconceivable blossoms of entirely new mental universes.