Igor Novikov, theoretical astrophysicist, will deliver two lectures as the Thomas Gold Lecturer at Cornell University this month. Novikov, a professor at the Theoretical Astrophysics Center in Copenhagen, Denmark, will give a free, public lecture titled "Can We Change the Past?" at 4:30 p.m. on Thursday, Oct. 17, in Schwartz Auditorium, Rockefeller Hall. He will discuss the nature of time and its asymmetry from the past to the future and its possible reverse.

On campus for the week of Oct. 14, with an office in the Astronomy Department, Space Sciences Building, Novikov also will deliver a joint Physics/Astronomy Colloquium at 4:30 p.m. on Wednesday, Oct. 16, "Tidal Interaction of Stars With Supermassive Black Holes in Galactic Nuclei," also in Schwartz Auditorium.

Novikov has been director of the Theoretical Astrophysics Center since 1994. He also is professor of astrophysics at the Copenhagen University, where he has been since 1991. He previously was head of the Department of Theoretical Astrophyics at the Lebedev Physical Institute in Moscow and has been professor at Moscow State University. From 1974 to 1990 he was head of the Department of Relativistic Astrophysics at the Space Research Institute in Moscow.

Novikov has authored or co-authored 15 books on cosmology and astrophysics, and wrote, with A. Sharov, a biography of Edwin Hubble, E. Hubble, Life and Work (Cambridge University Press, 1992).

The Thomas Gold Lecture Series is sponsored by Cornell's Department of Astronomy and the College of Arts and Sciences in honor of Thomas Gold, professor of astronomy emeritus. The series brings a noted astronomer to Cornell each year for public lectures and colloquia with faculty and students.