The discovery of time travel in 2016 allows an experiment wherein a pair of twins at opposite ends of a "time pendulum" are sent simultaneously forward and backward in time, then swung in the opposite directions, increasing the scale of the swing by a factor of ten each time, to witness both the past of Earth and humanity, and their future.
| Date | Publication | Publisher | Type | Page | |
|---|---|---|---|---|---|
| September 1987 |
|
Project Pendulum | Walker & Co. | Novel | |
| February 1989 |
|
Project Pendulum | Hutchinson | Novel | |
| November 1989 |
|
Project Pendulum | Bantam Spectra | Novel | 3 |
| February 1990 |
|
Project Pendulum | Beaver Books | Novel | |
| July 1991 |
|
Opération Pendule | J'ai Lu | Novel | |
| March 1994 |
|
Opération Pendule | J'ai Lu | Novel | |
| August 2001 |
|
Cronos | ibooks | Omnibus | 113 |
| April 2011 |
|
Times Three | Subterranean Press | Omnibus | 379 |
| April 2011 |
|
Times Three | Subterranean Press | Omnibus | |
| September 2011 |
|
Project Pendulum | Gateway / Orion | Novel | |
| October 2012 |
|
Times Three | Subterranean Press | Omnibus | |4 |