Fermi paradox

The Fermi paradox is a contradiction that the physicist Enrico Fermi pointed out in 1950. The paradox questioned the likelihood of extraterrestrial intelligent life. It attempts to answer a basic question:

" Are we humans the only technologically advanced civilization in the universe? "

Strictly speaking, these are only an apparent paradox, since it reasonable assumptions, its accuracy is doubtful.

Due to the age of the universe and the vast numbers of stars life should be distributed outside of the earth, assuming the emergence of life on Earth would not be unusual event (see Rare Earth hypothesis). Enrico Fermi discussed in 1950 on the way to lunch at Los Alamos National Laboratory with Edward Teller, Emil Konopinski and Herbert York alleged UFO sightings and a cartoon from the New Yorker magazine about extraterrestrials and finally asked "Where is everybody? ". Why were observed neither spaceships other space residents still other traces of extraterrestrial technologies. A detailed scientific study of the problem began in the early 1970s with studies by Michael H. Hart, which is why even the term Fermi -Hart paradox will be used.

• 3.1 Lack of interest
• 3.2 Lack of visibility
• 3.3 They exist - we have only missed
• 3.4 They exist - we are ignored
• 3.5 They exist - we ignore them

• 7.1 Video

Basic consideration

Core of the Fermi paradox is the following consideration:

Starting from the assumption that the earth is not an absolute exception among the planets and our solar system is not unique ( in the sense that it contains intelligent life ), the (not yet quantifiable ) option is in the room that other technical civilizations in our galaxy exist. Our galaxy is about 100,000 light -years wide. A sub- light drive, such as the project Icarus at a rate by a factor of 0.01 to 0.1 of the speed of light would require a ( straight and without intermediate stops) to about ten million years on this route. The galaxy is about 10 billion years old. A crossing would have been possible several times in the duration of their existence.

If in the Milky Way even a single civilization exists that is capable of interstellar colonization, then the entire galaxy could be completely colonized within a few million years. The Milky Way is now much older than the required 20 and 40 million years; consequently extraterrestrial civilizations should exist in our galactic neighborhood anywhere. So far, however, no evidence of extraterrestrial civilizations could be found.

The paradox can be summarized as follows:

" The widespread belief that there is in our universe many technologically advanced civilizations, in combination with our observations that suggest the opposite, is paradoxical and suggests that either our understanding or our observations are incorrect or incomplete. "

In short: If it ' they ' are, why are not they here?

The Fermi Paradox is closely connected to the Drake equation, by which the probability of the simultaneous existence of other civilizations in the Milky Way to be estimated. As yet, however, most of the parameters of the Drake equation are unknown, it can currently contribute little to the solution of the paradox.

To explain the paradox, there are several approaches; it can (which, due to the laws of nature for all civilizations alike apply ) and are weak arguments distinction between principled arguments. The problem of weak arguments is that Fermi assumes that only a single civilization is necessary to cause the paradox described. However, this civilization must retain their basic features over geological periods. However, weak arguments make no fundamental obstacles dar. So we would have to assume that evolve all civilizations similar and therefore fail at the same obstacles.

The following passage was out of work The Fermi Paradox: An Approach Based on Percolation Theory by Geoffrey A. Landis translates to something like:

" Deny Proposed solutions to the Fermi paradox either completely the possibility of extraterrestrial civilizations, an assumption which so far can not be proven, or accept the possibility of extraterrestrial technical civilizations and observations to suggest why these have not yet colonized the Milky Way. The statements involve doing the proposals that such civilizations collapse or destroy itself, they run out of resources, they choose not to colonize or colonize, but ignore us aware. The problem with these attempts at explanation is that they all assume a similarity of the motifs of civilizations over extremely long periods of time. If even a single civilization for the colonization of the Milky Way decides these attempts at explanation must fail. "

Principal arguments

The hypothesis of the unusual Earth / We are indeed alone

One thought is that multicellular life in the universe is exceptionally rare because Earth-like planets are potentially rare. It had come together many unlikely coincidences, made ​​the life on earth possible. Such coincidences are the position of the Sun in the Milky Way (radiation), the position of the Earth in the solar system (temperature), the existence of a relatively large moon ( stabilization of the Earth's axis ), etc. (cf. Hoimar of Ditfurth, children of the universe ).

Finally, the parameters of the Drake equation are chosen so that in our galaxy there is only one civilization in this explanation - ours. In this respect, the Fermi paradox loses its paradoxical character, because already one of the basic assumptions is rejected.

Although this hypothesis is widely considered convincing as necessarily contradict other of the rarity of Earth-like planets (which is discovered by the increasing number of exoplanets is close ) or assert complex life need not necessarily Earth-like conditions to develop (see carbon chauvinism ).

A special form of this argument assumes that the development of higher intelligence in the course of evolution is extremely unlikely. Thus, the formation or the presence of higher intelligence is in any of the complex life forms that existed in the past to the ground is known.

Impossibility of interstellar colonization / Communication

The condition of the Fermi paradox " ... a civilization that is capable of interstellar colonization ... " may possibly principle not be fulfilled. Under these circumstances, there could be in the Milky Way several technical civilizations, but are spatially too far apart to influence each other.

To illustrate an example called the distance from our Sun to the nearest star, Proxima Centauri, which could be achieved even at the speed of light only after 4.2 years. Since exceeding the speed of light, according to current knowledge is not possible to ask a few questions:

• Whether a civilization (yet) could muster the resources to achieve foreign star systems, when a situation occurs that makes such things seem worthwhile or even necessary.
• What can accept time delay in the communication populations in different star systems need to even have the necessary for a civilization cohesion.

Distribution pattern / diffusion of civilization

After an approach by Geoffrey A. Landis, the colonization of the Galaxy can be studied by means of percolation theory as a diffusion -like process. Landis starts from two premises:

Under these circumstances, the galaxy would not equally populated, rather, "bubbles" would emerge, which are bounded by stagnant colonies. Within these bubbles then no further colonization would take place. Conversely, it could then also give bubbles with a high " density civilization ". The relationship between these bubbles is influenced significantly by the probability of successful colonization and the development of the colonizing or stagnant civilization type.

• If P is now below a threshold, the colonization will stop after a finite number of colonies.
• If P is above the limit, is almost filled the entire galaxy, with the exception of a few small bubbles.
• If P is close to the limit, the galaxy is crossed by a fractal structure, exist in both large populated and non- populated areas. We would live in a non populated area.

Mathematics A priori argument

After a consideration of the astrophysicist J. Richard Gott speaks against the likelihood of the hypothesis that galaxies are usually largely colonized since then almost all living things would be a member of such super civilizations. If there were such civilizations, then it would be unlikely for statistical reasons, to have been born just as a member of a relatively small, young and not yet colonized civilization such as ours. This purely mathematical consideration is equivalent to the so-called Doomsday argument and not an indicator of the existence of extraterrestrial life, but merely states that, if there should be such a life, it does not colonized. Thus Fermi's paradox is resolved because J. God negates its basic assumption.

Other arguments

Lack of interest

Even if the technical possibility of interstellar communication or colonization exists, the question arises whether a civilization ever has an economic or philosophical interest in using this technique. Our civilization has so far taken no great effort to consciously send out signals, and human space flight is largely limited to sending out probes. Even in principle possible interplanetary space flights to be questioned in terms of their economic and scientific sense.

Lack of visibility

The transmission of radio signals to communicate is relatively inefficient. If all civilizations within a short time to more efficient methods of communication over go ( self-focusing particle beams or the like. ), The proportion of radio waves over which would make a civilization noticeable decreases.

It was also proposed that a fundamental axiom of information theory could be behind the lack of recognizable signals. Information theory states that a maximum compressed message for those is indistinguishable from the background noise, do not know the compression algorithm. SETI however looks for all signals, an unmodulated sine wave only after the simplest. The basic assumption of SETI is the willingness of other life forms to communicate clearly by a simple signal to be discovered. For these reasons, today's search methods would overlook a highly compressed transfer simple.

They exist - we've only missed

This hypothesis is based on the fact that all visiting civilizations stagnate or die, rather than expand the long term. This can not be excluded, because the duration of human existence is to cosmological scale such small that even little changes to continue living our species for hundreds of thousands of years. This could civilizations in time and space simply too far apart to meet each other. This hypothesis contradicts the possibility of Von Neumann probes, which could have a far longer lifespan than their original civilization. A civilization that sends Von Neumann probes, this could also limit their reproduction so that each star system would assign a maximum probe. This probe would only reproduce when their own lifetime expires. You may also be stationary as buoys and, for example, emit only a weak signal.

They exist - we are ignored

With this assumption, it is assumed that under all civilizations in our neighborhood a consensus prevails to avoid contact. This speculation is also sometimes referred to as the " Galactic Zoo".

The obligation of non-intervention and the consequences if neglected, is the subject of the 1964 published novel, it is not easy to be Arkady and Boris Strugatsky of a god.

The science fiction writer Gene Roddenberry formulated this as " Prime Directive ", a strict non -interference, at least as long as civilization has not exceeded a defined threshold, such as the technological capacity to interstellar travel.

They exist - we ignore them

It is assumed that extraterrestrial civilizations have been attempts to make contact, both in the past and in the present made ​​, this would be ignored by modern science, however, or could not be perceived or would be kept secret by one or more governments. It is processed in several science fiction novels and films, as represented, among others, in The Hitchhiker's Guide to the Galaxy, and is also in some interpretations of UFO sightings, conspiracy theories and followers of various pseudo-sciences.

Conclusion

The current database does not allow to come to an estimate based on the Drake equation in the frequency of extraterrestrial civilizations. Only in the next few years or decades, Earth-like planets may be found in other planetary systems, until then all solutions must remain speculative.