Back from the dead, with some new information. To be honest, I did realized it three posts ago, but really engaged in going around, it seems going around is no more...
May the stars bury their children before themselves, before they even grow white hair, cuz these fuccs are hella long-lived already they can't stand to see a spec of rock out-live them...
- Val
I really expected to create along the history of one single planet up to 2 or 3 civilizations that appeared after the other after several catastrophes and life plane reboots, if all life had to start again it would take around 3 billion years to build back to complex life :P in my suppositions, given Vol has a life-expectancy of 11,6Gyrs, I've considered 9 to 10 billion years of history (I've really wrote a script on that). But lol, when I was making a post about the moon on my personal Facebook page, I've stumbled upon this Wikipedia article.
"[...] In about 600 million years from now, the level of carbon dioxide will fall below the level needed to sustain C3 carbon fixation photosynthesis used by trees."
Nice Val, you've done well, trying to ride a sciencey blog but stumbled upon the most fictional stuff you could ever have write.
For sake of scale, if mankind annihilate itself today in a Thanos-snap scale event, along with all other surface creatures and plants, let's say, nuclear war, in 600 million years the fish could walk back into the land and re-colonized the continents, and even at the end of this period, a new civilization could find itself in a dying world willing to escape the solar system. I take this because it took 600 million years from the first aquatic beings, first fungi, plants, flowers, dinosaurs, to the dawn of man. Fishes appeared 530 million years ago, if land-life disappeared today, along with some other shallow water fish, new fishes, advanced ones, could rise back, although at this point most of life-forms in the sea had achieved evolutionary stability, ie, their niches are only theirs, but no absolute doubts.
Now, we can certainly assume at most, a planet can only give birth to life in the way of an advanced technical species twice in a sun-like star lifetime.
TOP lines represent a sun-like star life-cycle.
BOTTOM lines represent an Earth-like planet life-cycle.
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On the bottom lines, the first red line means the planet formation, up to a billion years of crust cooling and stuff, the three blue lines represent the time life has spent in the seas, and the green line is how much longer Earth can sustain life as we know it, we are in the middle of the green band right now, the other black bars are how much time Earth will be devoid of life(?) under our sun.
Back at astrophysics, we can recall the fact that by the fact the Sun is constantly raising it's energy output (ie, brightness), life have been given the opportunity to grow more complex, as said before, the bacteria in your fridge and stomach will never develop more than they already are if energy and ambient conditions are kept the same.
Sure thing, we stumbled upon the verge of what is possible to find out there, there is this even narrower band of time and space where complex life can rise and develop into radio-astronomy.
A star is too young, planets aren't formed yet, or even, only primitive aquatic life exists there.
Star is too old, planets are already devoid of life, there is this narrow band of time, in a star's life-time where life can explode but it is at best, only 1 billion years-wide, and it must have happened the just right things - an impossible chain of events that leads to something like, you and me, here.
You may have heard already of the Drake Equation:
It takes numbers, the sheer number of each possibility, have ever someone thought about the this Narrow Slice we just discussed?
According to Drake and his colleagues in 1961, N is around 20 [link],some conservative and educated guess.
Carl Sagan supposed N is around 10 [link].
As said by Carl, if it is the case, we may not forget to consider that destroy ourselves tomorrow may be on our unwritten schedule, then we may be the only ones bearing in the galaxy.
Taking such low estimates about the number of technical civilizations out there, and evenly spread them through the galaxy, which disk cross-section is ~7.85 billion square light-years, gives us a kinda-bubble of ~392,7 million Ly², then, if we travel ~11.180 Ly in any direction away from Earth we may find only deserts devoid of complex life anymore than that of bacteria and algae.
Some modern estimates of low hope, argue, we are the only ones, even in the observable universe, giving N as 9.1x10⁻¹¹.
Other estimates take N up to a 15.6 million advanced civilizations, yet the Fermi Paradox still haunts us via the lack of any sign of all those aliens...
Considering the narrow slice is something Fc and L were supposed to mean, but are too ambiguous, they suppose everyone bears at the same time. Then how could we represent the narrow slice? A planet may develop a civilization once or twice in the span of a billion years only, supposing some catastrophe wipes out any evolutionary achievement upon land, maybe a couple more times if they manage to recover quick enough from any wars or near-extinction event.
So far we assume:
- A planet can only give birth to complex land life in a short span of ~1Gyr.
- As such, life leading to a technical civilization may only occur once or twice, but maybe a couple more times if previous evolutionary steps are not completely lost.
- Such cultures never left their home-planet, therefore are transmitting from there.
- G-type stars are the only ones capable of supporting the right lighting to allow complex life.
- All G-type stars are roughly the same age.
- Such stars are evenly spread throughout the galaxy.
1Gyr is roughly 1/5th of a given planet around a sun-like star on it's verge of atmospheric / chemical death. And around 1/10th of it's star's total life-span.
There are ~13860 stars within 100 light years, from which only ~512 are sun-like stars, from which 38 have confirmed planets. [link]
Carrying that to a macro-scale:
3,7% of stars around us are sun-like, of those, 7,4% have planets, and up to date, 0,00195% of that have confirmed life forms - EARTH.
From that, we could already guess, there is 14.8 billion suns out in the galaxy, from which 1 billion may have planets, from which 2.135.640 (2.1 million) may have life like our own planet.
Then, assuming this may be correct, or close to, as far as 0,0001443% (1/100th of a 100th) of all G-type stars have life.
For as well, we may consider some extra ~947 K-type stars per 100Ly radii, for sake of more liberal results later, which 21 (2,21%) have planets around, 947 would be ~6,83% of all stars. Assuming the same of life percentage goes for them.
As well, we are searching for communicative planets, there enters our narrow slice:
We can consider a technical species may only appear once, for a period of 100.000 years (approximate existence of modern humans), before threatening itself or developing radio-astronomy, broadcasting for a period of 500 years, which may be deliberate, considering our modern daily radio emissions are not able to go as far into the cosmos and still be detectable.
We represent that by:
ns = ~0,00002 | The period of time a technical species live safe from self-threatening tech is 2 hundredths of a thousandth of it's planet / star current age.
For what we may consider, that other hominids co-existed with us throughout history, potential species for the control of Earth, and that we ended up killing everyone else as well.
18 species of the Homo gender have lived within last 2,2Myrs, considering more 3 sub-species of the Homo sapiens, counting 21 candidates for dominant species
sr = ~0,0476 | Accounting up for ~4,76% of "success rate" in achieving a "stable" society and etc.
Updated formula may look like this:
N = R* x fp x ne x fl x fi x ns x sr x fc x L
Considering R* as the total stars in the Milky Way ~400 billion.
Since we already tackled a good estimate of planets with life, lets make the cuts taking the Narrow Slice and Success Rate as species into account.
Val's CONSERVATIVE estimates
2.135.640 x ns = 42,71 planets may have potentially technical species.42,71 x sr = 2 species may have achieved success in taking over their planet, and probably, had success in not destroying themselves in the way to radio-astronomy.
Assuming we are one, the other may be out there yet.
Val's LIBERAL estimates
(2.135.640 + 3.942.276 K-type stars probably with life) x ns = 121,55 planets may have potentially technical species.121,55 x sr = 5,78, between 5 and 6 species may have achieved radio-astronomy and are currently trying to communicate.
Val's AVERAGE estimates
At least 82 planets may have some contactable advanced species.
From which between 3 and 4 may have achieved radio-astronomy or some degree of technology / space travel.
Currently, we are one of those which is trying to communicate and have some degree of interplanetary travel in development.
At this point, only ~0,000015% of the stars in the Milky Way may harbor life in some degree.
Therefore, ~0,000000000205% of the stars in the galaxy may contain some advanced species.
If all the galaxies in the local group were the same size as the Milky Way, there would be 189 technological civilizations. And as galaxies are as old as the Universe itself, there would have existed a total of 529 civilizations in the local Group, if it is impossible for a culture to outlive a star in life-span.
Also, it would have been possible the existence of other 6 ~ 7 ancient civilizations only in our own galaxy.
Estimated via the number of stars in the Andromeda and Triangulum galaxies, that the number of civilizations in the local group is around 24, and at least the chance of previous 43 long gone already, the sheer number of other minor galaxies are statistically nullified.
- M.O. Valent, 19/08/2019
