Our
galaxy, The Milky Way, contains roughly between 200 and 400 billion stars. Most
of those stars are very dim red and brown dwarfs that cannot be seen even
through the largest telescopes but we can predict their existence in different
ways. The lower end estimates for total number of planets in our galaxy are
around 100 billion. It’s very probable that it is larger than that.
The
Drake equation was written by Dr. Frank Drake in 1961. It’s used to estimate the
number of alien civilizations that could exist in our galaxy at any given time,
which would be advanced enough to communicate with us (or at least be detected
by us receiving their radio signals). The equation states as follows:
Where V is the
result number of civilizations to be expected. R is the rate of star formation
within the galaxy; fp is a fraction of formed stars that have
planets; ne is an average number
of potentially habitable (depending on size, chemical composition and
temperature) planets per star; fl is a fraction of those planets that developed
life on their surface; fi is a fraction of planets with life on which it
has evolved to the point of intelligence and creating civilization; fc is a fraction of those civilizations that
developed technology allowing to send signals into space and L is average time
for which those civilizations exist (send signals).
It’s very hard to estimate the
parameters for the equation as there’s no way for us to just check them. If we
take lower estimates for number of stars with planets in our galaxy and assume
that there is 20% chance for a habitable planet orbiting any star; 13% chance
for a habitable planet developing life, 50% chance for that life becoming
intelligent over the whole time of its existence; 20% chance of them developing
signal sending technology and sending the signal for the average time of 100
thousand years we get that there should be 780 civilizations sending signals
into space right now in our galaxy alone. With the diameter of our galaxy being
roughly 100 thousand light-years, we should be able to already detect signals
from most of them as all electromagnetic waves travel through empty space at
the speed of light.
Yet we haven’t detected any
signals from any intelligent life so far. The huge disproportion between the number
of signals expected based on the Drake equation (example value of 780 for our
galaxy) and real number of signals received (zero) is called Fermi’s paradox.
The paradox was presented by Fermi actually long before the creation of Drake’s
equation and is not limited to the Milky Way alone. If we consider the entire
observable universe, the expected number of civilizations is many orders of
magnitude higher (tens of billions).
All of the above estimates don’t
account for advanced civilizations building spaceships and travelling through
the galaxy colonizing different planets. Had advanced civilizations died out, they would probably have left some detectable
artifacts, remnants of their technology sending some kinds of signals.
Maybe the
probability of life development is much smaller than we think? Or civilizations
destroy themselves much faster than we hope?
Comments
But who knows what future will bring...
It blew my mind completely. It opened my eyes, because I never thought about aliens this way before.
1. There are billions of stars in the galaxy that are similar to the Sun, many of which are billions of years older than Earth,
2. With high probability, some of these stars will have Earth-like planets, and if the Earth is typical, some might develop intelligent life.
3. Some of these civilizations might develop interstellar travel, a step the Earth is investigating now.
4. Even at the slow pace of currently envisioned interstellar travel, the Milky Way galaxy could be completely traversed in about a million years.
According to this line of thinking, the Earth should have already been visited by extraterrestrial aliens.
Fermi has asked why, if there are many other life forms on planets in Milky Way, haven't we received any signal from them. The answer is simple: there aren't many. Life on Earth might have been the winning lottery ticket in the galaxy, something that happened due to incredibly good set of circumstances. So good that it did not happen anywhere in our entire galaxy. Remember, we are looking for a planet not only with developed life, not only with it being intelligent, creating civilisations - but also we are assuming that it tried to communicate with us quite recently, when we were in any way ready to receive such signals, hasn't gone extinct yet, and many other factors. In this way Fermi's Paradox is not really a paradox - there just aren't that many other inhabited planets, potentially none in Milky Way.
My point is that maybe there actually is life on other planets, but why do we assume they would like to contact us?
Perhaps they don't want to be discovered at all. It is very likely that they are much more intelligent than humans and developed technology that allows them to be hidden from the dangers of the outside world. At the same time they can observe life on Earth, big problems our planet face and so on. It may be true that, from their perspective, there is nothing interesting on Earth, so it is not worth to conquer us.
I know all this looks like a sci-fi movie scenario and seems to be unreal but... you can say that only from human point of view though.
I'm sure that there is another life in space, it is too big to not have other civilisations. Why haven't we already communicated with them? Maybe they don't want to or maybe we have technology, which is not yet capable of doing this.
Not matter how low probability, if you try something enough times it will succed and we have very, very large amount of stars and planets in our galaxy.
One of the most common cause is that our technology isn't developed enough. That they are much more intelligent than people, so they don't want to live with them. In some of the movies "aliens" (people/creatures from other civilizations) consider themselves as superior, so they don't want to waste their time, and in other they are caring towards people and are afraid what could happend if people met them.
Personally I am skeptical if it is about aliens or other civilizations, but I'm ready to change my mind (if there is some irrefutable proof) :)
In my opinion there's another life in the space, but it's impossible to get their signals. How should we do it? With WiFi, 3G, HSDPA, sounds, lights, fire?
Lots of years ago, there was nothing. No fire, no sounds, no electricity. We invented it. The same is with another life in the space - if exists, they have their own inventions which we don't know.
What's more, it's not a miracle that life started on Earth. We are just adapted to live here. We breathe air and need water to survive because these factors existed on Earth. First, it was Earth and then people occured. Not inversly.
“Or civilizations destroy themselves much faster than we hope?” - I really like this question. Actually, it reminds me of us - human beings. It looks like we’ll destroy ourselves even before the technology will be advanced enough to know if aliens exist.
Also, I think if we would have a Neumann probe now - we would know much more about the place we live in.
Some time ago I came across really interesting and funny video on this subject. Some disturbing thoughts was shared in it. What if, simply, we are too stupid for other life forms. So stupid they don't bother to contect us.
https://youtu.be/HO6ONMLfg5A?t=456
the equation is a bit overwhelming for human been to fill in the equation variables :),
maybe there are lives out there, perhaps they send singles as we do but maybe they use different way of communication not radio waves as we do.
People on our planet live only a second compared to time of universe. If one civilizations send a signal to other-
it could last millions of years to get into other place. We live too short to be able to receive signals from others. Maybe signals are being sent
in different way than we expecting them. It is really hard to find out why we don't know about others. We should also refer to concept with more
numbers of space-time dimension, like theory Kaluzy-Klenia.
Moreover we are only able to explore our galaxy, but there are billions of galaxies in visible universe, what if life greatly develops in somewhere and we can't notice it?
If you want to get more information about the Voyager and the golden plate here it is: https://www.youtube.com/watch?v=E118gyMUrLU
One of my favourite Sci-fi writer is Stanislaw Lem. His novels show to reader what could we meet somewhere in the future. The plot of his most famous book, "Solaris", is about a contact with alien "beign", that can't be even understood by whole mankind. Why? Because this alien beign is a whole planet, that after milions of years of its existence it's so complex, that his most visible "signs" of his alien life cannot be understood even by whole generations of scientists. And yes, at the same time, this "beign" is in some way conscious... But how can we communicate with such beigns that doesn't have brains like us? Why would we want to do that? For such beign, i think, we are like some sort of natural phenomenon. It could happen, that some aliens are like us, but it is nearly impossible.
I'm very passionately interested in the human future, on the Moon and Mars particularly, and elsewhere in the solar system. In this moment there are research and experiments about whole Universe. I think that retrieval foreign civilization is a matter of time.
Seager equation
When talking about our rights of physics we know very little about it, about rights that rule our world. For me we need to recognize more of them to discover the "aliens" somewhere in space.
It could be right that we are not smart enough to notice them or they are just simply hiding. Who knows?^^
PART I:
https://www.youtube.com/watch?v=sNhhvQGsMEc
PART II:
https://www.youtube.com/watch?v=1fQkVqno-uI
It's funny how humans are trying to seek the aliens and civilizations on the other planets but still we cannot even make peace between races of people on the single one.