Are we alone in the Universe?
Well this question is capable of deriving itself onto multiple implications. For example:
- (One possibility) Are we, each one of us, alone even on Earth itself?
- (Another possibility) Are we alone in some particular way knowing that we are not alone for we are many members of a species?
- (Another possibility) Are we, human beings on Earth, alone as intelligent beings in the Universe?
Re-reciting these items a little bit:
- From Descartes it’s plausible that each man or woman can only assert his or her own existence.
- Even, non-descartesianly, if each one of us could assert his neighbour’s existence, could he or she feel yet alone in spirit?
- In the Universe as we best know it today, has no other civilization arisen so that it’s capable of communicating with us? (And, on the other hand, has no other civilization picked up the signals we have been sending out?)
***
Today we want to touch the third possibility of the subject title’s question for this indeed seems to be a very odd one.
The best we know of the Universe nowadays is that it is comprised by millions of galaxies and trillions of stars. This number is so big that it’s hard to grasp the magnificence of it all.
There is however an equation that has long been popularized by the TV Series Documentary by Carl Sagan made in 1970′s titled Cosmos. This popularized equation is Drake’s equation.
Drake’s equation is just a multiplication of probabilities, nothing more, nothing less. So in principle, it calls for a very simple arithmetic calculation.
Let’s see what the Drake equation states:
N = R . F_p . N_e . F_e . F_i . F_c . L
Where, borrowing Wikipedia’s text :
- N = the number of civilizations in our galaxy with which communication might be possible;
and
- R* = the average rate of star formation per year in our galaxy
- fp = the fraction of those stars that have planets
- ne = the average number of planets that can potentially support life per star that has planets
- fℓ = the fraction of the above that actually go on to develop life at some point
- fi = the fraction of the above that actually go on to develop intelligent life
- fc = the fraction of civilizations that develop a technology that releases detectable signs of their existence into space
- L = the length of time for which such civilizations release detectable signals into space.[3]
For the sake of playing a bit with the equation, let’s borrow, also from the Wikipedia’s piece, one possible scenario:
- R* = 10/year (10 stars formed per year, on the average over the life of the galaxy)
- fp = 0.5 (half of all stars formed will have planets)
- ne = 2 (stars with planets will have 2 planets capable of developing life)
- fl = 1 (100% of these planets will develop life)
- fi = 0.01 (1% of which will be intelligent life)
- fc = 0.01 (1% of which will be able to communicate)
- L = 10,000 years (which will last 10,000 years)
Drake’s values then give N = 10 × 0.5 × 2 × 1 × 0.01 × 0.01 × 10,000 = 10.
***
So Drake’s Equation, with the support of these above simulating values, gives us this number of 10 civilizations in the Milky Way, the galaxy where our Solar System and we ourselves reside.
Let’s multiply this 10 with millions and millions of other galaxies, everything, in all directions, respecting only some appropriate elapsed time so that heavier chemical elements might have been given the chance to be formed. That is, our Universe is 13.7 billion years, but a few initial billion years must have had passed so that gigantic stars could have formed the heavier chemical elements that we now find on Earth and on which life as we know it depends.
If we were to continue that multiplication, this 10 would grow so big that mind would indeed reel, for it’s hard to think that millions of other civilizations may exist and yet no other single one of them has come into contact with us and conversely no other single one of them has apparently responded to our sent-out signals.
As we close today’s message, let’s wish one another “peace”.
Let us indeed have peace!
