Astrophysics (Greek: Astro - meaning "star", and Greek: physis – φύσις - meaning "nature") is the branch of astronomy that deals with the physics of the universe, including the physical properties of celestial objects, as well as their interactions and behavior. Among the objects studied are galaxies, stars, planets, exoplanets, the interstellar medium and the cosmic microwave background. Their emissions are examined across all parts of the electromagnetic spectrum, and the properties examined include luminosity, density, temperature, and chemical composition. Because astrophysics is a very broad subject, astrophysicists typically apply many disciplines of physics, including mechanics, electromagnetism, statistical mechanics, thermodynamics, quantum mechanics, relativity, nuclear and particle physics, and atomic and molecular physics. In practice, modern astronomical research involves a substantial amount of physics. The name of a university's department ("astrophysics" or "astronomy") often has to do more with the department's history than with the contents of the programs. Astrophysics can be studied at the bachelors, masters, and Ph.D. levels in aerospace engineering, physics, or astronomy departments at many universities.

Neil deGrasse Tyson ( /ˈniːəl dəˈɡræs ˈtaɪsən/ born October 5, 1958) is an American astrophysicist and science communicator. He is currently the Frederick P. Rose Director of the Hayden Planetarium at the Rose Center for Earth and Space, and a research associate in the department of astrophysics at the American Museum of Natural History. Since 2006 he has hosted the educational science television show NOVA scienceNOW on PBS, and has been a frequent guest on The Daily Show, The Colbert Report, Real Time with Bill Maher, and Jeopardy!. It was announced on August 5, 2011, that Tyson will be hosting a new sequel to Carl Sagan's Cosmos: A Personal Voyage television series.

Tyson was born as the second of three children in the borough of Manhattan in New York City, but was raised in the Bronx. His mother, Sunchita Feliciano Tyson, was a gerontologist and his father, Cyril deGrasse Tyson, was a sociologist, human resource commissioner for the New York City mayor, John Lindsay, and was the first Director of HARYOU. Tyson attended the Bronx High School of Science (1972–1976, astrophysics emphasis) where he was captain of the wrestling team and was editor-in-chief of the school's Physical Science Journal. Tyson had an abiding interest in astronomy from the age of eleven, following his visit to the Hayden Planetarium at age nine. Tyson recalls that "so strong was that imprint [of the night sky] that I'm certain that I had no choice in the matter, that in fact, the universe called me." He obsessively studied astronomy in his teens, and eventually even gained some fame in the astronomy community by giving lectures on the subject at the age of fifteen.

Michio Kaku (加来 道雄, Kaku Michio^?, born January 24, 1947) is an American theoretical physicist, the Henry Semat Professor of Theoretical Physics in the City College of New York of City University of New York, a co-founder of string field theory, a futurist, and a "communicator" and "popularizer" of science. He has written several books about physics and related topics; he has made frequent appearances on radio, television, and film; and he writes extensive online blogs and articles. He has written two New York Times best sellers, Physics of the Impossible (2008) and Physics of the Future (2011). He has hosted several TV specials for BBC-TV, the Discovery Channel, and the Science Channel.

Kaku was born in San Jose, California to Japanese immigrant parents. His grandfather came to the United States to take part in the clean-up operation after the 1906 San Francisco Earthquake^{[citation needed]}. His father was born in California but was educated in Japan and spoke little English. Both his parents were put in the Tule Lake War Relocation Center, where they met and where his two brothers were born.