I can provide you with one of the most compelling arguments that scientists often cite in support of the existence of extraterrestrial life: the sheer vastness of the universe.
The observable universe is incredibly immense, containing billions of galaxies, each with billions of stars. Many of these stars are similar to our Sun and could potentially have Earth-like planets in their habitable zones, where conditions might be suitable for life as we know it.
Based on this vast number of potential habitats, it is statistically likely that some of them could support the development of life. Moreover, recent discoveries of exoplanets (planets outside our solar system) in the habitable zone of their respective star further strengthen the argument. For example, the Kepler Space Telescope has identified numerous exoplanets, some of which possess similar characteristics to Earth.
Additionally, the discovery of extremophiles—organisms on Earth that can thrive in extreme conditions, such as deep-sea hydrothermal vents or acidic environments—suggests that life might be more resilient and adaptable than previously thought. This resilience increases the chances of life existing in extreme environments on other planets or moons within our own solar system, such as Mars or the icy moon Europa.
While these arguments are not direct evidence of extraterrestrial life, they contribute to the growing body of evidence that suggests the possibility of life beyond Earth. However, no definitive evidence has been found to confirm the existence of extraterrestrial life. Ongoing scientific exploration and advancements in technology continue to shed light on this fascinating topic.