Fermi's Paradox

From TinWiki.org

Fermi's Paradox is the apparent contradiction between the probability of extraterrestrial life in our galaxy and the lack of supporting empirical data. Enrico Fermi (1901-1954) was an Italian-born American physicist who asked the simple question: "Where are they?" This question has baffled some of the brightest scientific minds, and hence was given the suitable name: Fermi's Paradox.

1 Brief Background
- 1.1 The Drake Equation
2 Solving the paradox
3 References
4 External links
5 Relevant Discussion Threads

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Brief Background

With at least 100 billion, and perhaps as many as 400 billion, stars in our Milky Way Galaxy, the probability seems high that our galaxy would be home to many other intelligent beings. Even if a small percentage of 100 billion stars have Earth-like planets in their orbit, one could infer there to be many advanced civilizations in our galactic neighborhood. Assuming extraterrestrials have human-like behavior and motivation, scientists have estimated that even at sub-light speeds, an advanced civilization could colonize the galaxy in 5-50 million years.

Based on logical scientific assumptions, Fermi realized that alien beings would have had ample time to explore and colonize the galaxy many times over. Yet looking around, he saw no clear indication of their existence. Since Fermi first posed his question, many scientists and philosophers have attempted to resolve the paradox.

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The Drake Equation

A decade after Fermi first posed his question, astronomer Frank Drake came up with a formula to estimate the Number (N) of currently existent civilizations capable of advanced communication. The equation is written as:

N = (R_s)(f_p)(n_p)(f_b)(f_i)(f_c)(L_c)

where R_s is the rate of star formation in the Galaxy, f_p is the fraction of those stars with planetary systems, n_p is the mean number of planets suitable for life per planetary system, f_b is the fraction of those planets suitable for life on which life actually developed, f_i is the fraction of those planets with life on which intelligent organisms have evolved, f_c is the fraction of those intelligent species that have developed communicative civilizations, and L_c is the mean lifetime of those civilizations.

The first three factors are essentially astronomical in nature, the next two are biological, and the last two are sociological. Critics of the Drake Equation have argued that the biological and sociological aspects of the equation are unknown variables requiring too much guesswork.

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Solving the paradox

While attempting to tackle Fermi's Paradox, scholars have entertained a number of different ideas and scenarios.

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Unique Earth

This school of thought attempts to solve the paradox by hypothesizing that life is either unique to Earth or extremely rare. It states that the long and delicately balanced sequence of events leading to life on Earth could have been broken by a relatively small variation; hence we are lucky and extraterrestrials either do not exist or rarely come into existence due to this fine balance. Critics of the rare Earth scenario argue that, despite the lack of empirical data, the great deal of circumstantial evidence cannot be ignored. Theoreticians have come up with different formulas similar to the Drake Equation to illustrate the likelihood of the existence of other intelligent beings.

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We are the first

This angle postulates that we are simply the first intelligent beings to evolve in the galaxy. Again, this possibility is thought to be unlikely by the same premise which is used to argue against Unique Earth scenario. Given that the age of our galaxy is estimated to be 12 to 15 billion years, it is unreasonable to assume that terrestrial type planets capable of supporting life would not have formed within first several billion years of the birth of the galaxy.

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Colonizing the galaxy is technologically unfeasible

Attempts to argue that traversing the enormous distances of space is a near technological impossibility are widely regarded as a myth today. An idea for a nuclear starship dates back to the 1960's and is still regarded as one of the most practical forms of interstellar travel. Estimates predict that using known nuclear fission technology, waves of colonization could be sent traveling at 0.06 the speed of light and still colonize the galaxy in approximately four million years.

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We are one of the colonies

Many well-known intellectuals have conjectured that we are the result of a colonization effort. Critics have argued that this would only make sense if they had arrived over a billion years ago. At that time, multicellular life had not formed yet, and their colonization would have been in the form of a "seed." Evidence suggests we have not been "managed," as genetic manipulation brings into question a list of poor design considerations, for instance "swallowing down the wrong pipe."

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Advanced civilizations extinguish themselves

The possibility that advanced civilizations inevitably destroy themselves is also an option. One example of this would be nuclear war. Another example could be a biological or nanotech disaster. Perhaps some high energy physics experiment might go wrong and create a singularity, causing the destruction of a planet. Many feel that, while these are all within the realm of possibility, it is very unlikely that every civilization would fail to survive its "childhood."

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Alien code of non-interference

This is similar to Star Trek, in which more advanced civilizations, already part of a larger galactic community, are forbidden from interfering with less advanced civilizations. While this might make some sense from a sociological viewpoint, it again lacks empirical evidence, and one is forced to make assumptions on alien technology.

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