What is a black hole? Why do we remember the past but not the future? If time had a beginning, does it have an end?We don’t have the answers to some of the universe’s biggest questions. What we do know often feels bleak, such as the notion that in a billion years there will most likely be no life on Earth. Or the reality that someday the entire human race will probably be forgotten.Nonetheless, people search for answers. These are some of the cosmic questions that haunt the human experience.Guest: Dennis Overbye, the cosmic affairs correspondent for The New York Times.Background reading: When the largest space observatory ever built sent its images back to Earth, here’s what astronomers saw.In space you can’t hear a black hole scream, but apparently you can hear it sing. Hear what that sounds like.For more information on today’s episode, visit nytimes.com/thedaily. Transcripts of each episode will be made available by the next workday.