Search for alien life in and outside the Milky Way galaxy continues. Scientists believe that with trillions of galaxies in our universe there is a huge possibility of the existence of intelligent alien life which are waiting to be discovered. However, a new study suggests that galaxies such as our spiral galaxy is more suitable for life than giant elliptical galaxies.

In his study, Daniel Whitmire, a retired professor of astrophysics who is an instructor at the University of Arkansas' Department of Mathematical Sciences argues against a 2015 study that claims that giant elliptical galaxies are more likely to host advanced, technological civilisations than spiral disk galaxies like Milky Way. The five-year-old study that was published in journal Monthly Notices of the Royal Astronomical Society on May 1, 2015, suggested that there is a higher likelihood for life to emerge in such enormous galaxies because it hosts "many more stars and have low rates of potentially lethal supernovae."

As per the news release on the University's website, Whitmire believes that the previous study contradicts an important statistical rule called the principle of mediocrity. Popularly known as the Copernican Principle, the scientific notion states that "in the absence of evidence to the contrary, an object or some property of an object should be considered typical of its class rather than atypical." The principle has been subjected to controversy in the past and was also used by Sir Isaac Newton to calculate the approximate distance to the star Sirius.

Meanwhile, Whitmire suggests that the 2015 paper has some issues with regard to the principle. In his theory, he goes on to explain that Earth must be considered typical and not atypical of technological civilisations in our universe.

"The evolution of elliptical galaxies is totally different than the Milky Way," Whitmire said. "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 sterilised," he added.

These giant elliptical galaxies are believed to make up 10 to 15 percent of galaxies in the Virgo supercluster and the size range can go over to one hundred trillion stars. The stars that are found in these galaxies are considered much older than the stars of spiral galaxies. Some of the prominent examples of such galaxies are M49, M105, IC 1101, Maffei 1 and more. The size and mass of these galaxies vary vastly ranging from 3000 to 700,000 light-years in diameter.

"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 explains.

The milky way galaxy
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The study was published on April 13, in Monthly Notices of the Royal Astronomical Society.