New study examines which galaxies are best for intelligent life
Giant elliptical galaxies are not as likely as previously thought to be cradles of technological civilizations such as our own, according to a recent paper by a University of Arkansas astrophysicist.
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He also had to show that most stars and therefore planets reside in large elliptical galaxies in order to nail down his argument that the earlier paper violated the principle of mediocrity.
According to the principle of mediocrity, Earth and its resident technological society should be typical, not atypical, of planets with technological civilizations elsewhere in the universe. That means that its location in a spiral-shaped disk galaxy should also be typical. But the 2015 paper suggests the opposite, that most habitable planets would not be located in galaxies similar to ours, but rather in large, spherical-shaped elliptical galaxies.
In his paper, Whitmire suggests a reason why large elliptical galaxies may not be cradles of life: They were awash in lethal radiation when they were younger and smaller, and they went through a series of quasar and star-burst supernovae events at that time.
"The evolution of elliptical galaxies is totally different than the Milky Way," said Whitmire. "These galaxies went through an early phase in which there is so much radiation that it would just completely have nuked any habitable planets in the galaxy and subsequently the star formation rate, and thus any new planets, went to essentially zero. There are no new stars forming and all the old stars have been irradiated and sterilized."
If habitable planets hosting
intelligent life are unlikely in large elliptical galaxies, where most stars and planets reside, then by default galaxies such as the Milky Way will be the primary sites of these civilizations, as expected by the principle of mediocrity, Whitmire said.More information: Daniel P Whitmire. The habitability of large elliptical galaxies, Monthly Notices of the Royal Astronomical Society (2020).
Journal information: Monthly Notices of the Royal Astronomical Society
Provided by University of Arkansas