Imagine the Universe!
Imagine Home  |   Ask an Astrophysicist  |  
Ask an Astrophysicist

The Question

(Submitted March 14, 1997)

Just curious about Black holes, and I wanted to know if the gravitational field of a black hole would pull an object in faster than the speed of light. If I understand correctly objects cannot go faster than the speed of light our they would be going back in time. If the acceleration of a black hole is constant, would an object that got sucked into a black holes velocity increase beyond the speed of light the closer it got to the black hole?

The Answer

The answer to your question is that the motion of a particle near a black hole is not governed by Newton's laws of motion in the familiar sense. The correct equations for motion near a black hole predict that an object on a radial path into the hole will have a velocity which approaches the speed of light as the object approaches the event horizon. For more information, I can only refer you to a textbook on general relativity, such as the one by Steven Weinberg ("Gravitation and Cosmology..." 1972 (Wiley: New York).

I hope this is of some help.

Tim Kallman

Previous question
Main topic
Next question

Imagine the Universe is a service of the High Energy Astrophysics Science Archive Research Center (HEASARC), Dr. Alan Smale (Director), within the Astrophysics Science Division (ASD) at NASA's Goddard Space Flight Center.

The Imagine Team
Acting Project Leader: Dr. Barbara Mattson
All material on this site has been created and updated between 1997-2012.

DVD Table of Contents
Educator's Index