Even if there is no multiverse, no swirling plethora of other dimensions creating new universes in a cycle without beginning or end, the one universe we know about is damned big, and damned old.
And we’ve only barely dipped a toe into it.
Given all that cosmic real estate, and considering the known universe is three or more times older than our little planet, and considering how tenacious and opportunistic and diverse life is here on Earth, it would seem outrageously unlikely that Earth is the only place in the cosmos where life exists and evolves. Look at how much life has happened on our world in just 4.5 billion years, then imagine how much life could evolve on millions of planets over 15 billion years.
Now consider the possibility of multiple universes, and infinite time. Boggles, doesn’t it?
Odds are, we are not alone.
Here is an interesting article from Slate discussing the implications of all that, and the effort to discover who else is out there. The author is Evgenya Shkolnik, a professor in Arizona State University’s School for Earth and Space Exploration. Her article is good nutrition for gray cells.