The Fermi paradox

If there are so many advanced civilizations out there, where is everybody?

The implication of this paradox is that we are alone in this universe. However, the question whether there is life in space is inherently more complex than this, and thought must be given to the massive distances involved, development of space travel technology, and other factors.

Astronomer Frank Drake penned an equation that approximates the probability of existence of technologically advanced life in space and that we will find out about it anytime soon.

N = R_* * f_p * n_e * f_l * f_i * f_c * L

N = Number of intelligent civilizations in space
R_* = Number of stars
f_p = Fraction of stars with planets
n_e = Probability of number of planets with habitable environments
f_l = Fraction of planets where life has originated
f_i = Chance of life evolving into a condition of intelligence
f_c = Percentage of life that has technology to send out signals into space
L = The "longetivity" factor, from 0 to 1, gauging the lifespan of the average intelligent civilization

Due to the number of unknowns in this equation that we will probably not find out within our lifetimes, it is still a mere conjecture on the subject. Estimates on the number of intelligent civilizations in the universe range from over the millions to zero.

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If there are other intelligent beings in the universe, then why aren't they here?

Though the scales of distance in the universe are large, the lengths of time necessary for traversing it is not as large as the time used during evolution. And because the amount of time from where civilization is developed to the point where interstellar travel and von Neumann probes seem reachable are significantly smaller, it seems likely that when a civilization reaches this point they will quickly spread around the universe.

Thus, if there are some out there, then why haven't they spread to here, or at least close enough to be detected? In some ways, it implies the lack of these other civilizations.

There have been various attempts to explain this apparent problem. Some suggest that we've been set aside, like a preserve, to achieve technology on our own. Others suggest that they transcend much before they really spread out into space. Or that they're actually here, but hidden on the nanoscale, or in some other manner.

Also see: Fermi's Paradox, Drake Equation, the great filter

Please Note: Yes, there are assumptions here, and possible explanations, but this is a short descriptive writeup, not a long paper to discuss it in detail. A search on the web for the Fermi Paradox will turn up many articles about it which deal with many of the things I have left out.

If there are other intelligent beings in the universe, then why aren't they here?

First of all, I have to question the use of the word "other". Are you suggesting that there are intelligent being on Earth? I assume you're referring to humans.

That having been said, okay, pretend there are other "intelligent" beings out there, same intelligence as humans. Why haven't they come here? Why haven't we gone there? We're the same intelligence as them, right?

The correct question would be "if there are much more intelligent beings in the universe, then why aren't they here?" The answer is because their first contact with us was an intercepted transmission of the Jerry Springer Show.

Intelligence, as we think of it, is a very narrow spectrum. Extraterrestrials would think completely different from us (I am Spock had some insights from a SETI scientist on this). Math is not a social construct in that 1+1=2 &c, but life on other planets would think this in a completely different manner, completely undecypherable by humans.

While we're at it, what we consider life is a very narrow spectrum. In Devil in the Dark (TOS) they discovered Horta which is a silicon based lifeform. Bones, of course, instantly argues with that analyses "That's impossible!" After all, we've never seen a lifeform like that, so it can't exist.

Or maybe they're hugely advanced but have never been enticed by that big void filled with little glowing white things. Maybe they're just interested in neurobiology, genetics, and philosophy. and mathematics.

Define intelligent. Define life.

Ohh... But look at all those assumptions you've gone and made!

1. Extraterrestrials are not now living among us.

2. The population density of Intelligent life is high enough that it is practical to commute.

3. Aliens can survive away from the planet's surface. (Low G isn't healthy for everyone).

4. Aliens are not xenophobic pacifists.

5. They find us interestering (But they're intelligent! Exactly...)

6. They reproduce fast enough to populate the stars.

7. They can see us. (Meat?!)

8. There is a spoon.

9. They would come at the right time and/or stay long enough to intersect with human civilization.

10. The life cycle of an intelligent species is long enough to leave a star system. (We're almost there... Cut it out with those nukes!)

If they were here, would we know?

If we were to detect, say, a century from now (to be pessimistic about the advance of our technology), another civilization which we were interested in visiting, I suspect that we would have many technologies at our disposal for doing so undetected. Nanotechnology is the most obvious.

Given this, I find it impossible to believe that any visitor to our civilization would be so clumsy as to attempt and fail to conceal themselves, as so often happens in popular accounts of extraterrestrials.

It is an unpleasant thought, but the possibility that we are being watched without our knowledge does not even require invocation of Clarke's Third Law any more. Of course, the probability of such surveillance is another matter, but set that aside for a moment.

A better argument against extraterrestrial intelligent life is that we haven't heard them yet...the "Why is the universe silent?" question. As the SETI folks argue, it makes more sense for us to listen. Nothing on the radio yet, though. Perhaps we should be theorizing about how our technology may soon advance to the point where radio waves will no longer escape our planet.

Enrico Fermi's paradox is not of other intelligent beings throughout the universe, rather of advanced civilizations, advanced enough to travel around the long distances implied between life-supporting biospheres(planets where life has resources to develop).

What it is not, and most people don't realize this, is that it isn't a valid paradox for every form of intelligent beings around the Universe. We can see this looking at Humanity itself: It is a form of intelligent life but it will take god knows how many more years just to travel to Mars, let's not comment travelling to a near star or even to a populated planet. This very concept of populated planet is enigmatic. How would we know in what planets to search for life, specially where to search for advanced life forms. In other words, even if there were intelligent beings capable of long distance Universe travels, how they would know that there is intelligent life on Earth, what would be so special about our little sun and planets that would tease an alien curiosity?

They could search around lots and lots of other planets and never even get around our Sun, taking account of the infinity of planets there are. They could have been from a distant galaxy and, searching around thousands of planets near them and not finding evidence of intelligence life, gived up trying to find one.

And if you manage to dismiss all above questions, there is still that ulterior one, the most philosophical of all: How intelligent are we? If such advanced civilizations existed that would be able to travel around stars through the Universe, would we really be considered intelligent? Would the corrupt virus that is humanity to a certain extent be considered smart, while they watch wars, brother against brother and people lost in egoistical prides? If aliens watched Hollywood movies, would they consider us intelligent?

Maybe the real question is: If there are many advanced civilizations out there, and if they in fact could visit Earth, would human life mean ANYTHING to them? Which in the end leaves us just with an existentialist paradox: What is the meaning of humanity itself?