In preparation for a career in academic medicine, I worked as a medical house officer at Columbia-Presbyterian Hospital from 1966 to 1968 and then joined Ira Pastan's laboratory at the National Institutes of Health as a Clinical Associate.

I had learned that science is a rewarding, active process of discovery, not the passive absorption of what others had discovered.

Anyone graduating from medical school in 1966 had first to fulfill military service before launching a career. Fiercely opposed to the Vietnam War, I sought to avoid it through an assignment to the Public Health Service.

The public schools I attended were dominated by athletics and rarely inspiring intellectually, but I enjoyed a small circle of interesting friends despite my ineptitude at team sports and my preference for reading.

For me, being able to engage with the details when necessary, when there's a challenge, when there's a particularly important pivot, yes, you have to do that. But in general, a leader needs to trust their commanders, needs to trust the team they've assembled, to actually execute in the right way.

Users are trying to discover apps; we are trying to improve the app discovery process, and developers are trying to reach users. If you step back, it's a problem we solved with search and ads in search.

I'm an optimist. My own fiction, while it has its own dark warnings about pitfalls ahead, depicts the potential of science to improve society by networking human minds.

In my lifetime, we have lost a President, a Civil Rights leader and a Presidential candidate - all to gun violence.