Astrophysicist Hakeem Oluseyi has lived a life that sounds almost impossible: a childhood marked by poverty, violence, and constant upheaval; a teenage obsession with Einstein; a stint in the Navy; addiction and recovery; work as a janitor; and eventually a PhD in physics from Stanford.

In this conversation, Michael Shermer and Oluseyi talk about his new book, Why Do We Exist?, and the biggest questions science can ask: what came before the Big Bang, whether the multiverse is real, why the universe seems fine-tuned for life, what dark matter and dark energy really mean, and why alien civilizations may be far rarer than we hope.

Hakeem Oluseyi is a multidisciplinary astrophysicist, multi-patented inventor, award-winning author and journalist, and internationally recognized educator. His new book is Why Do We Exist?: The Nine Realms of Universe That Make You Possible.