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77-400: Stephen Baxter may refer to: Stephen Baxter (author) (born 1957), English science fiction author Stephen Baxter (footballer) (born 1965), Northern Irish football manager and ex-player Stephen B. Baxter (1929–2020), American historian Stephen Baxter (historian) (born 1969), historian of Anglo-Saxon and Norman England Steven Baxter,
154-656: A G2 star due to Earth's television and telecommunication broadcasts. In the absence of an apparent natural cause, alien observers might infer the existence of a terrestrial civilization. Such signals could be either "accidental" by-products of a civilization, or deliberate attempts to communicate, such as the Arecibo message . It is unclear whether "leakage", as opposed to a deliberate beacon, could be detected by an extraterrestrial civilization. The most sensitive radio telescopes on Earth, as of 2019 , would not be able to detect non-directional radio signals (such as broadband ) even at
231-477: A geological scale , let alone a cosmological one . Since there are many stars older than the Sun, and since intelligent life might have evolved earlier elsewhere, the question then becomes why the galaxy has not been colonized already. Even if colonization is impractical or undesirable to all alien civilizations, large-scale exploration of the galaxy could be possible by probes . These might leave detectable artifacts in
308-402: A better estimation of how common these potentially habitable worlds are. The Hart–Tipler conjecture is a form of contraposition which states that because no interstellar probes have been detected, there likely is no other intelligent life in the universe, as such life should be expected to eventually create and launch such probes. Self-replicating probes could exhaustively explore a galaxy
385-459: A character in the British drama The Second Coming Steve Baxter (entrepreneur) (born 1971), Australian investor and entrepreneur Steve Baxter (musician) (1952–2020), American songwriter and guitarist [REDACTED] Topics referred to by the same term This disambiguation page lists articles about people with the same name. If an internal link led you here, you may wish to change
462-418: A civilization might try to harness a large part of the energy produced by a star. He proposed a hypothetical "Dyson sphere" as a possible means: a shell or cloud of objects enclosing a star to absorb and utilize as much radiant energy as possible. Such a feat of astroengineering would drastically alter the observed spectrum of the star involved, changing it at least partly from the normal emission lines of
539-524: A fraction of a light-year away, but other civilizations could hypothetically have much better equipment. A number of astronomers and observatories have attempted and are attempting to detect such evidence, mostly through SETI organizations such as the SETI Institute and Breakthrough Listen . Several decades of SETI analysis have not revealed any unusually bright or meaningfully repetitive radio emissions. Exoplanet detection and classification
616-537: A full-time author in 1995. He is also a chartered engineer and fellow of the British Interplanetary Society . Fermi paradox The Fermi paradox is the discrepancy between the lack of conclusive evidence of advanced extraterrestrial life and the apparently high likelihood of its existence. Those affirming the paradox generally conclude that if the conditions required for life to arise from non-living matter are as permissive as
693-536: A host of fortuitous circumstances, such as a galactic habitable zone , a star and planet(s) having the requisite conditions, such as enough of a continuous habitable zone , the advantage of a giant guardian like Jupiter and a large moon , conditions needed to ensure the planet has a magnetosphere and plate tectonics , the chemistry of the lithosphere , atmosphere , and oceans, the role of "evolutionary pumps" such as massive glaciation and rare bolide impacts. Perhaps most importantly, advanced life needs whatever it
770-537: A natural stellar atmosphere to those of black-body radiation , probably with a peak in the infrared . Dyson speculated that advanced alien civilizations might be detected by examining the spectra of stars and searching for such an altered spectrum. There have been some attempts to find evidence of the existence of Dyson spheres that would alter the spectra of their core stars. Direct observation of thousands of galaxies has shown no explicit evidence of artificial construction or modifications. In October 2015, there
847-500: A perfect universe for us to be in, because nobody would be able to boss us around, and we'd get to be the voyagers, the Star Trek people, the starship builders, the policemen, and so on." The rapid increase of scientific and technological progress seen in the 19th and 20th centuries, compared to earlier eras, led to the common assumption that such progresses will keep growing at exponential rates as time goes by, eventually leading to
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#1732781035331924-407: A series of calculations on the probability of earthlike planets, the probability of life given an earth, the probability of humans given life, the likely rise and duration of high technology, and so on. He concluded on the basis of such calculations that we ought to have been visited long ago and many times over." Teller remembers that not much came of this conversation "except perhaps a statement that
1001-408: A significant fraction of the size of the observable universe . Even if such civilizations are rare, the scale argument indicates they should exist somewhere at some point during the history of the universe, and since they could be detected from far away over a considerable period of time, many more potential sites for their origin are within range of human observation. It is unknown whether the paradox
1078-632: A significant number of extant civilizations in the Milky Way. This assumes the mediocrity principle , by which Earth is a typical planet . The second aspect of the Fermi paradox is the argument of probability: given intelligent life's ability to overcome scarcity, and its tendency to colonize new habitats , it seems possible that at least some civilizations would be technologically advanced, seek out new resources in space, and colonize their star system and, subsequently, surrounding star systems. Since there
1155-498: A slow speed-of-light dialogue between vastly distant neighbors. Rather than contending with the long delays a radio dialogue would suffer, a probe housing an artificial intelligence would seek out an alien civilization to carry on a close-range communication with the discovered civilization. The findings of such a probe would still have to be transmitted to the home civilization at light speed, but an information-gathering dialogue could be conducted in real time. Direct exploration of
1232-435: A trilogy co-authored with Arthur C. Clarke , is connected to Clarke's four Space Odyssey novels. The trilogy consists of Time's Eye , Sunstorm , and Firstborn . Another novel is based on a synopsis written by Clarke, The Light of Other Days . Baxter has also published a Doctor Who novel, The Wheel of Ice . His most recent sequel is The Massacre of Mankind , an authorised sequel to H. G. Wells' The War of
1309-531: A water world. In other words, 32 percent continental mass may be high among water worlds..." Brin continues, "In which case, the evolution of creatures like us, with hands and fire and all that sort of thing, may be rare in the galaxy. In which case, when we do build starships and head out there, perhaps we'll find lots and lots of life worlds, but they're all like Polynesia. We'll find lots and lots of intelligent lifeforms out there, but they're all dolphins, whales, squids, who could never build their own starships. What
1386-521: Is abiogenesis : a gradual process of increasing complexity of the first self-replicating molecules by a randomly occurring chemical process. Other proposed great filters are the emergence of eukaryotic cells or of meiosis or some of the steps involved in the evolution of a brain capable of complex logical deductions. Astrobiologists Dirk Schulze-Makuch and William Bains, reviewing the history of life on Earth, including convergent evolution , concluded that transitions such as oxygenic photosynthesis ,
1463-422: Is (nearly) impossible argue that the conditions needed for the evolution of life—or at least the evolution of biological complexity —are rare or even unique to Earth. Under this assumption, called the rare Earth hypothesis , a rejection of the mediocrity principle , complex multicellular life is regarded as exceedingly unusual. The rare Earth hypothesis argues that the evolution of biological complexity requires
1540-512: Is a very active sub-discipline in astronomy; the first candidate terrestrial planet discovered within a star's habitable zone was found in 2007. New refinements in exoplanet detection methods , and use of existing methods from space (such as the Kepler and TESS missions) are starting to detect and characterize Earth-size planets, to determine whether they are within the habitable zones of their stars. Such observational refinements may allow for
1617-423: Is also an active field of scientific research. This includes both efforts to find any indication of life, and efforts specifically directed to finding intelligent life. These searches have been made since 1960, and several are ongoing. Although astronomers do not usually search for extraterrestrials, they have observed phenomena that they could not immediately explain without positing an intelligent civilization as
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#17327810353311694-446: Is an English hard science fiction author. He has degrees in mathematics and engineering . Strongly influenced by science fiction pioneer H. G. Wells , Baxter has been vice-president of the international H. G. Wells Society since 2006. His fiction falls into three main categories of original work plus a fourth category, extending other authors' writing; each has a different basis, style, and tone. Baxter's " Future History " mode
1771-645: Is an earlier example of Baxter's blending of alternate history with science fiction. A more recent work in this direction is the Northland Trilogy , an alternate prehistory that begins with Stone Spring , set ten thousand years ago in the Stone Age , followed by Bronze Summer and Iron Winter , set in alternate versions of the Bronze Age and the Iron Age . In 2009, Baxter became a judge for
1848-401: Is an ordered system that can sustain itself against the tendency to disorder , Stephen Hawking's "external transmission" or interstellar communicative phase, where knowledge production and knowledge management is more important than transmission of information via evolution , may be the point at which the system becomes unstable and self-destructs. Here, Hawking emphasizes self-design of
1925-557: Is based on readings in evolutionary biology and human/animal behaviour. Elements of this appear in his future histories (especially later works like the Destiny's Children series and Flood / Ark ), but here it is the focus. The major work in this category is Evolution , which imagines the evolution of humanity in the Earth's past and future. The Mammoth Trilogy , written for young adults, shares similar themes and concerns as it explores
2002-578: Is based on research into hard science . It encompasses the Xeelee Sequence , which consists of nine novels (including the Destiny's Children trilogy and Vengeance/Redemption duology that is set in alternate timeline), plus three volumes collecting the 52 short pieces (short stories and novellas) in the series, all of which fit into a single timeline stretching from the Big Bang singularity of
2079-457: Is everybody?" (Teller's letter), or "Don't you ever wonder where everybody is?" (York's letter), or "But where is everybody?" (Konopinski's letter). Teller wrote, "The result of his question was general laughter because of the strange fact that, in spite of Fermi's question coming out of the blue, everybody around the table seemed to understand at once that he was talking about extraterrestrial life." In 1984 York wrote that Fermi "followed up with
2156-416: Is explored both in fiction and in scientific hypothesizing. In 1966, Sagan and Shklovskii speculated that technological civilizations will either tend to destroy themselves within a century of developing interstellar communicative capability or master their self-destructive tendencies and survive for billion-year timescales. Self-annihilation may also be viewed in terms of thermodynamics : insofar as life
2233-444: Is no significant evidence on Earth, or elsewhere in the known universe, of other intelligent life after 13.8 billion years of the universe's history, there is a conflict requiring a resolution. Some examples of possible resolutions are that intelligent life is rarer than is thought, that assumptions about the general development or behavior of intelligent species are flawed, or, more radically, that current scientific understanding of
2310-526: Is not only a potential biosignature but also a critical factor in the emergence of detectable technological civilizations. Another hypothesis in this category is the "Water World hypothesis". According to author and scientist David Brin : "it turns out that our Earth skates the very inner edge of our sun's continuously habitable—or ' Goldilocks '—zone. And Earth may be anomalous. It may be that because we are so close to our sun, we have an anomalously oxygen-rich atmosphere, and we have anomalously little ocean for
2387-509: Is relatively early in the potential timeline of intelligent life in the universe, as loud aliens would otherwise be observable by astronomers. Earlier in 2013, Anders Sandberg and Stuart Armstrong examined the potential for intelligent life to spread intergalactically throughout the universe and the implications for the Fermi Paradox. Their study suggests that with sufficient energy, intelligent civilizations could potentially colonize
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2464-475: Is stronger for the Milky Way galaxy or for the universe as a whole. The theories and principles in the Drake equation are closely related to the Fermi paradox. The equation was formulated by Frank Drake in 1961 in an attempt to find a systematic means to evaluate the numerous probabilities involved in the existence of alien life. The equation is presented as follows: Where N {\displaystyle N}
2541-661: Is the number of technologically advanced civilizations in the Milky Way galaxy, and N {\displaystyle N} is asserted to be the product of The fundamental problem is that the last four terms ( f l {\displaystyle f_{l}} , f i {\displaystyle f_{i}} , f c {\displaystyle f_{c}} , and L {\displaystyle L} ) are entirely unknown, rendering statistical estimates impossible. The Drake equation has been used by both optimists and pessimists, with wildly differing results. The first scientific meeting on
2618-468: The Sidewise Award for Alternate History , the first former winner among the panel. Another category, outside of the main body of Baxter's independent work, is sequels and installments of science-fiction classics. His first novel to achieve wide recognition (winning three literary awards) was The Time Ships , an authorised sequel to H. G. Wells' The Time Machine . The Time Odyssey series,
2695-548: The eukaryotic cell , multicellularity , and tool -using intelligence are likely to occur on any Earth-like planet given enough time. They argue that the Great Filter may be abiogenesis, the rise of technological human-level intelligence, or an inability to settle other worlds because of self-destruction or a lack of resources. Paleobiologist Olev Vinn has suggested that the great filter may have universal biological roots related to evolutionary animal behavior. In 2021,
2772-564: The human genome ( transhumanism ) or enhancement via machines (e.g., brain–computer interface ) to enhance human intelligence and reduce aggression , without which he implies human civilization may be too stupid collectively to survive an increasingly unstable system. For instance, the development of technologies during the "external transmission" phase, such as weaponization of artificial general intelligence or antimatter , may not be met by concomitant increases in human ability to manage its own inventions. Consequently, disorder increases in
2849-439: The search for extraterrestrial intelligence (SETI), which had 10 attendees including Frank Drake and Carl Sagan , speculated that the number of civilizations was roughly between 1,000 and 100,000,000 civilizations in the Milky Way galaxy. Conversely, Frank Tipler and John D. Barrow used pessimistic numbers and speculated that the average number of civilizations in a galaxy is much less than one. Almost all arguments involving
2926-473: The Drake equation suffer from the overconfidence effect , a common error of probabilistic reasoning about low-probability events, by guessing specific numbers for likelihoods of events whose mechanism is not yet understood, such as the likelihood of abiogenesis on an Earth-like planet, with current likelihood estimates varying over many hundreds of orders of magnitude . An analysis that takes into account some of
3003-422: The Fermi paradox is a function of the scale or the large numbers involved: there are an estimated 200–400 billion stars in the Milky Way (2–4 × 10 ) and 70 sextillion (7×10 ) in the observable universe . Even if intelligent life occurs on only a minuscule percentage of planets around these stars, there might still be a great number of extant civilizations, and if the percentage were high enough it would produce
3080-455: The Fermi paradox that rely on empirical evidence—that there are many potentially habitable planets , and that humans see no evidence of life. The first point, that many suitable planets exist, was an assumption in Fermi's time but is now supported by the discovery that exoplanets are common. Current models predict billions of habitable worlds in the Milky Way. The second part of the paradox, that humans see no evidence of extraterrestrial life,
3157-567: The Great Silence, and silentium universi (Latin for "silence of the universe"), though these only refer to one portion of the Fermi paradox, that humans see no evidence of other civilizations. In the summer of 1950 at Los Alamos National Laboratory in New Mexico , Enrico Fermi and co-workers Emil Konopinski, Edward Teller, and Herbert York had one or several lunchtime conversations. In one, Fermi suddenly blurted out, "Where
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3234-617: The Solar System has yielded no evidence indicating a visit by aliens or their probes. Detailed exploration of areas of the Solar System where resources would be plentiful may yet produce evidence of alien exploration, though the entirety of the Solar System is vast and difficult to investigate. Attempts to signal, attract, or activate hypothetical Bracewell probes in Earth's vicinity have not succeeded. In 1959, Freeman Dyson observed that every developing human civilization constantly increases its energy consumption, and he conjectured that
3311-464: The Solar System, such as old probes or evidence of mining activity, but none of these have been observed. The second form of the question is "Why are there no signs of intelligence elsewhere in the universe?". This version does not assume interstellar travel, but includes other galaxies as well. For distant galaxies, travel times may well explain the lack of alien visits to Earth, but a sufficiently advanced civilization could potentially be observable over
3388-528: The Worlds . In 2010, Baxter began working on a new series with Terry Pratchett . This collaboration produced five books, The Long Earth , The Long War , The Long Mars , The Long Utopia and The Long Cosmos . Baxter has written non-fiction essays and columns for such publications as Critical Wave and the British SF Association's Matrix . Baxter's story " Last Contact "
3465-414: The ability to construct a radio telescope are presumed to be a natural advance for technological species, theoretically creating effects that might be detected over interstellar distances. The careful searching for non-natural radio emissions from space may lead to the detection of alien civilizations. Sensitive alien observers of the Solar System, for example, would note unusually intense radio waves for
3542-551: The available evidence on Earth indicates, then extraterrestrial life would be sufficiently common such that it would be implausible for it not to have been detected yet. The quandary takes its name from the Italian-American physicist Enrico Fermi : in the summer of 1950, Fermi was engaged in casual conversation about contemporary UFO reports and the possibility of faster-than-light travel with fellow physicists Edward Teller , Herbert York , and Emil Konopinski while
3619-605: The concepts of quiet, loud, and grabby aliens were introduced by Hanson et al. The possible "loud" aliens expand rapidly in a highly detectable way throughout the universe and endure, while "quiet" aliens are hard or impossible to detect and eventually disappear. "Grabby" aliens prevent the emergence of other civilizations in their sphere of influence , which expands at a rate near the speed of light. The authors argue that if loud civilizations are rare, as they appear to be, then quiet civilizations are also rare. The paper suggests that humanity's current stage of technological development
3696-753: The depiction of advanced theories and ideas, such as the true nature of the Great Attractor , naked singularities and the great battle between baryonic and dark matter lifeforms. The Manifold Trilogy is another example of Baxter's future history mode, even more conceptual than the Xeelee sequence. Each novel is focused on a potential explanation of the Fermi paradox . The two-part disaster series Flood and Ark (followed by three additional stories, "Earth III," "Earth II," and "Earth I") which also fits into this category, where catastrophic events unfold in
3773-444: The distances to the next location of living beings may be very great and that, indeed, as far as our galaxy is concerned, we are living somewhere in the sticks, far removed from the metropolitan area of the galactic center." Fermi died of cancer in 1954. However, in letters to the three surviving men decades later in 1984, Dr. Eric Jones of Los Alamos was able to partially put the original conversation back together. He informed each of
3850-429: The entire Milky Way galaxy within a few million years, and spread to nearby galaxies in a timespan that is cosmologically brief. They conclude that intergalactic colonization appears possible with the resources of a single solar system and that intergalactic colonization is of comparable difficulty to interstellar colonization, and therefore the Fermi paradox is much sharper than commonly thought. There are two parts of
3927-552: The facts and hypotheses that together serve to highlight the apparent contradiction: Fermi was not the first to ask the question. An earlier implicit mention was by Konstantin Tsiolkovsky in an unpublished manuscript from 1933. He noted "people deny the presence of intelligent beings on the planets of the universe" because "(i) if such beings exist they would have visited Earth, and (ii) if such civilizations existed then they would have given us some sign of their existence". This
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#17327810353314004-480: The group was walking to lunch. The conversation moved on to other topics, until Fermi later blurted out during lunch, "But where is everybody?"—although the exact quote is uncertain . There have been many attempts to resolve the Fermi paradox, such as suggesting that intelligent extraterrestrial beings are extremely rare , that the lifetime of such civilizations is short, or that they exist but (for various reasons) humans see no evidence. The following are some of
4081-399: The idea that technologically advanced civilizations are rare in the universe. Amedeo Balbi and Adam Frank propose the concept of an " oxygen bottleneck" for the emergence of technospheres. The "oxygen bottleneck" refers to the critical level of atmospheric oxygen necessary for fire and combustion . Earth's current atmospheric oxygen concentration is about 21%, but has been much lower in
4158-460: The latter may lead to biological or mental degeneration. Possible means of annihilation via major global issues, where global interconnectedness actually makes humanity more vulnerable than resilient, are many, including war, accidental environmental contamination or damage, the development of biotechnology , synthetic life like mirror life , resource depletion , climate change , or poorly-designed artificial intelligence . This general theme
4235-466: The level of technological advancement necessary to communicate. Along with non-intelligent life, such civilizations would also be very difficult to detect. A trip using conventional rockets would take hundreds of thousands of years to reach the nearest stars. To skeptics, the fact that in the history of life on the Earth, only one species has developed a civilization to the point of being capable of spaceflight and radio technology, lends more credence to
4312-431: The link to point directly to the intended article. Retrieved from " https://en.wikipedia.org/w/index.php?title=Stephen_Baxter&oldid=1224035934 " Category : Human name disambiguation pages Hidden categories: Short description is different from Wikidata All article disambiguation pages All disambiguation pages Stephen Baxter (author) Stephen Baxter (born 13 November 1957)
4389-561: The long noses of animals such as aardvarks and elephants. As he points out, "dolphins have had ~20 million years to build a radio telescope and have not done so". In addition, Rebecca Boyle points out that of all the species that have ever evolved in the history of life on the planet Earth, only one—human beings and only in the beginning stages—has ever become space-faring. New life might commonly die out due to runaway heating or cooling on their fledgling planets. On Earth, there have been numerous major extinction events that destroyed
4466-451: The majority of complex species alive at the time; the extinction of the non-avian dinosaurs is the best known example. These are thought to have been caused by events such as impact from a large meteorite, massive volcanic eruptions, or astronomical events such as gamma-ray bursts . It may be the case that such extinction events are common throughout the universe and periodically destroy intelligent life, or at least its civilizations, before
4543-593: The men that he wished to include a reasonably accurate version or composite in the written proceedings he was putting together for a previously held conference entitled "Interstellar Migration and the Human Experience". Jones first sent a letter to Edward Teller which included a secondhand account from Hans Mark . Teller responded, and then Jones sent Teller's letter to Herbert York. York responded, and finally, Jones sent both Teller's and York's letters to Emil Konopinski who also responded. Furthermore, Konopinski
4620-478: The nature of the universe itself is quite incomplete. The Fermi paradox can be asked in two ways. The first is, "Why are no aliens or their artifacts found on Earth, or in the Solar System ?". If interstellar travel is possible, even the "slow" kind nearly within the reach of Earth technology, then it would only take from 5 million to 50 million years to colonize the galaxy. This is relatively brief on
4697-559: The near future and humanity must adapt to survive in three radically different planetary environments. In 2013, Baxter released his short story collection Universes which featured stories set in Flood/Ark, Jones & Bennet and Anti-Ice universes. Baxter signed a contract for two new books, Proxima and Ultima , both of which are names of planets, and they were released in 2013 and 2014, respectively. A second category in Baxter's work
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#17327810353314774-420: The past and may also be on many exoplanets. The authors argue that while the threshold of oxygen required for the existence of complex life and ecosystems is much lower, technological advancement, particularly that reliant on combustion, such as metal smelting and energy production , requires higher oxygen concentrations of around 18% or more. Thus, the presence of high levels of oxygen in a planet's atmosphere
4851-461: The past to his Timelike Infinity (1993) singularity of the future. These stories begin in the present day and end when the Milky Way galaxy collides with Andromeda five billion years in the future. The central narrative is that of humanity rising and evolving to become the second most powerful race in the universe, next to the god-like Xeelee . Character development tends to be secondary to
4928-519: The premise that extraterrestrial civilizations exist. In 1975, Michael H. Hart published a detailed examination of the paradox, one of the first to do so. He argued that if intelligent extraterrestrials exist, and are capable of space travel, then the galaxy could have been colonized in a time much less than that of the age of the Earth. However, there is no observable evidence they have been here, which Hart called "Fact A". Other names closely related to Fermi's question ("Where are they?") include
5005-644: The present, past, and future of a small herd of mammoths found surviving on an island in the Arctic Ocean . A third category of Baxter's fiction is alternate history , based on research into history. These stories are more human, with characters portrayed with greater depth and care. This includes his NASA Trilogy , which incorporates research into NASA and its history; and the Time's Tapestry series, which features science-fictional interventions into our past from an alternate-history future. The novel Anti-Ice
5082-429: The progress level required for space exploration. The "universal limit to technological development" (ULTD) hypothesis proposes that there is a limit to the potential growth of a civilization, and that this limit may be placed well below the point required for space exploration. Such limits may be based on economic reasons , natural reasons (such as faster-than-light travel being impossible), and even limitations based on
5159-654: The self-organizing properties of life. It is possible that even if complex life is common, intelligence (and consequently civilizations) is not. While there are remote sensing techniques that could perhaps detect life-bearing planets without relying on the signs of technology, none of them have any ability to tell if any detected life is intelligent. This is sometimes referred to as the "algae vs. alumnae" problem. Charles Lineweaver states that when considering any extreme trait in an animal, intermediate stages do not necessarily produce "inevitable" outcomes. For example, large brains are no more "inevitable", or convergent, than are
5236-575: The size of the Milky Way in as little as a million years. If even a single civilization in the Milky Way attempted this, such probes could spread throughout the entire galaxy. Another speculation for contact with an alien probe—one that would be trying to find human beings—is an alien Bracewell probe . Such a hypothetical device would be an autonomous space probe whose purpose is to seek out and communicate with alien civilizations (as opposed to von Neumann probes, which are usually described as purely exploratory). These were proposed as an alternative to carrying
5313-589: The source. For example, pulsars , when first discovered in 1967, were called little green men (LGM) because of the precise repetition of their pulses. In all cases, explanations with no need for intelligent life have been found for such observations, but the possibility of discovery remains. Proposed examples include asteroid mining that would change the appearance of debris disks around stars, or spectral lines from nuclear waste disposal in stars. Explanations based on technosignatures , such as radio communications , have been presented. Radio technology and
5390-632: The species is able to develop the technology to communicate with other intelligent species. However, the chances of extinction by natural events may be very low on the scale of a civilization's lifetime. Based on an analysis of impact craters on Earth and the Moon, the average interval between impacts large enough to cause global consequences (like the Chicxulub impact ) is estimated to be around 100 million years. It may be that while alien species with intelligence exist, they are primitive or have not reached
5467-447: The species' own biology. This is the argument that technological civilizations may usually or invariably destroy themselves before or shortly after developing radio or spaceflight technology. The astrophysicist Sebastian von Hoerner stated that the progress of science and technology on Earth was driven by two factors—the struggle for domination and the desire for an easy life. The former potentially leads to complete destruction, while
5544-568: The uncertainty associated with this lack of understanding has been carried out by Anders Sandberg , Eric Drexler and Toby Ord , and suggests "a substantial ex ante probability of there being no other intelligent life in our observable universe". The Great Filter, a concept introduced by Robin Hanson in 1996, represents whatever natural phenomena that would make it unlikely for life to evolve from inanimate matter to an advanced civilization . The most commonly agreed-upon low probability event
5621-440: Was able to later identify a cartoon which Jones found as the one involved in the conversation and thereby help to settle the time period as being the summer of 1950. The Fermi paradox is a conflict between the argument that scale and probability seem to favor intelligent life being common in the universe, and the total lack of evidence of intelligent life having ever arisen anywhere other than on Earth. The first aspect of
5698-499: Was nominated for the 2008 Hugo Award for best short story. Baxter was born 13 November 1957 in Liverpool , England , and studied at St Edward's College , a Catholic grammar school. He then read mathematics at University of Cambridge , and obtained a doctorate in engineering at University of Southampton , and received an MBA from Henley Management College . Baxter taught maths, physics, and information technology before becoming
5775-480: Was not a paradox for others, who took this to imply the absence of extraterrestrial life. But it was one for him, since he believed in extraterrestrial life and the possibility of space travel. Therefore, he proposed what is now known as the zoo hypothesis and speculated that mankind is not yet ready for higher beings to contact us. In turn, Tsiolkovsky himself was not the first to discover the paradox, as shown by his reference to other people's reasons for not accepting
5852-435: Was some speculation that a dimming of light from star KIC 8462852 , observed by the Kepler space telescope , could have been a result of Dyson sphere construction. However, in 2018, observations determined that the amount of dimming varied by the frequency of the light, pointing to dust, rather than an opaque object such as a Dyson sphere, as the cause of the dimming. Those who think that intelligent extraterrestrial life
5929-545: Was that led to the transition of (some) prokaryotic cells to eukaryotic cells , sexual reproduction and the Cambrian explosion . In his book Wonderful Life (1989), Stephen Jay Gould suggested that if the "tape of life" were rewound to the time of the Cambrian explosion, and one or two tweaks made, human beings most probably never would have evolved. Other thinkers such as Fontana, Buss, and Kauffman have written about
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