Time's End by D.W. Patterson (Paperback)

Time's End: A Novel

Strings of time that can split a man in half, fast-time bubbles that can age him to death, or frozen time that can banish him forever. It was all just part of the job.
Pearce Rawlings was a physicist who wanted to do his job, manipulate time, and get his pay. But as usual the world had different ideas. He would soon be involved in a cosmic battle for freedom, one the governments of Earth for some reason were trying to lose.

But Rawlings and a few friends wouldn't quit the job even when facing death.
Time's End is set in the future (2700s) and is the second novel in the Future Chron Universe: Time Series.

The Future Chron Universe consists of 33 volumes including 9 novels, 1 short story, 15 novellas, and 8 short stories.

Hard Science Fiction - Old School.