Verified answer

Ray Bradbury's "Night Call, Collect".

http://spilledthejillybeans.blogspot.com/2012/01/b...

Timescape? It was written by Gregory Benford (and Hilary Foister, who was not credited), and an important character's name is Gordon Bernstein. Wikipedia explains part of the plot as follows:

"The story is written from two viewpoints, equidistant from the novel's publication in 1980. The first thread is set in a 1998 ravaged by ecological disasters such as algal blooms and diebacks on the brink of large scale extinctions. Various other events are mentioned in passing, such as student riots and an event of nuclear terrorism against New York City which took place before the events of the novel. This thread follows a group of scientists in the United Kingdom connected with the University of Cambridge and their attempts to warn the past of the impending disaster by sending tachyon-induced messages to the astronomical position the Earth occupied in 1962–1963. Given the faster-than-light nature of the tachyon, these messages will effectively reach the past. These efforts are led by John Renfrew, an Englishman, and Gregory Markham, an American most likely modeled on Benford himself.[4] Overseeing their efforts is Ian Peterson, a womanizing member of the World Council.

"The second thread is set in the University of California, San Diego, in La Jolla, California, in 1962 where a young scientist, Gordon Bernstein, discovers anomalous noise in a physics experiment relating to spontaneous resonance and indium antimonide. He and his student assistant, Albert Cooper (also likely based on the author and his experiences at UCSD), discover that the noise is coming in bursts timed to form Morse Code.

"The resulting message is made of staccato sentence fragments and jumbled letters, due to the 1998 team's efforts to avoid a grandfather paradox. Their aim is to give the past researchers enough information to start efforts on solving the pending ecological crisis, but not enough that the crisis will be entirely solved (thus making a signal to the past unnecessary and creating a paradox)."

Is that it?

By the way, if you liked that, have you seen the movie Frequency? The time-traveling radio waves plot device is the same, but the overall story is different—the combination is worth one viewing by any sci-fi fan.

I don't know that one, but you might enjoy Heinlein's THE DOOR INTO SUMMER.