Estimating the number of alien civilizations in our "Local Group" of galaxies is highly speculative and uncertain. The Local Group is a relatively small cluster of galaxies that includes the Milky Way (our galaxy), Andromeda, and several smaller galaxies. While there are billions of stars in our galaxy alone, estimating the number of potential alien civilizations is challenging due to several factors:
Uncertainty about Extraterrestrial Life: We have yet to discover any direct evidence of extraterrestrial life, so we do not have a clear understanding of how common or rare it might be. The existence of life beyond Earth is still an open question in scientific research.
Requirements for Life: We currently base our understanding of life on Earth, where conditions such as liquid water, organic molecules, and suitable environmental conditions are necessary for life as we know it. It is unclear how many other planetary systems in the Local Group or elsewhere might possess such conditions.
Fermi Paradox: The Fermi Paradox raises the question of why, given the vast number of potential habitable planets, we have not yet detected any signals or evidence of advanced civilizations. This paradox suggests that there may be various factors limiting the emergence or sustainability of intelligent civilizations.
Given these uncertainties, it is difficult to provide a reliable estimate of the number of alien civilizations within the Local Group. The Drake Equation is one attempt to estimate the number of detectable extraterrestrial civilizations in our galaxy, but it involves numerous assumptions and uncertainties.
Until we gather more evidence and explore other planetary systems within the Local Group and beyond, we can only speculate about the existence and abundance of alien civilizations.