Datum

Devin Roarke, a quantum physicist from MIT, was much too smart for the world in which he lived. He had ideas, lots of them that would make the world a better place to live; the only problem was he worked for Advanced Dynamics and they only wanted him to built weapons for them. He had too many ideas to allow AD to get their hands on them so after working for them for seven years, he disappeared one weekend, changed his name, and moved to a small town in Idaho where he could work on his ideas while teaching at a local college during the day. His ideas included concepts in time travel and temporal geometry, teleportation, and gravitational propulsion, plus a slew of other ideas. He built a time machine, but it was more than that, or possibly, less, only one foot across on the outside, but one hundred feet across on the inside.
Devin or rather, Ken DiAvero as he became known after leaving AD, had a friend who saw more potential in him than he let on. Her name was Meghan Grant, a mathematics instructor at the same college where Ken taught physics. Ken never showed anyone his house, at least outside the living quarters since it also incorporated the same temporal geometry as did his time machine that he named Datum, for Dimensionally Altered, Time-Variable Machine. One night when he had Meghan and another friend over for dinner, as he did occasionally, he announced that he would be gone for a while and had something to show them, inviting them to return the next Friday night. Meghan became too curious and instead of leaving for the night, she returned to stumble upon two of his secrets when she found him working in his laboratory, in a space that shouldn’t have existed. He could hardly deny what she’d seen, so he introduced her to Datum, as he preferred to refer to the acronym for his time machine.
One thing led to another when she joined him for a test flight through time. Reviewing the past was enlightening, but the jaunt into the future produced the most surprises. They learned that terrorists would soon embark on a spree of destruction focused on major cities around the world; Washington DC and Moscow were only the first two. While in Chicago having dinner, they met Jason and Jennifer; he was a doctor doing his residency at a local hospital and she was a teacher at a local high school; they were engaged to be married once his internship ended. Chicago became the next target that evening, killing Jason and Jennifer before Devin and Meghan could save themâ€"or could they?
Datum kept the couple outside of time when the nuclear weapon detonated. At that moment, they realized that their new friend didn’t need to die, but the only alternative was to expose them to a world that no one had seen before. Nuclear weapons destroyed civilization; even they gave it up as a lost cause. As time progressed, though, they watched civilization rebuild and eventually flourish for one hundred and fifty thousand years. The world existed in peace until aliens devastating civilization again, only to be attacked by another race of beings. The new aliens were nearly destroyed before victory was theirs, but were they friend or foe, though? Alas, they were the latter, imprisoning Earth’s peaceful people, forcing them to mine ores and manufacture metals to build a new starship. The four explorers from the past were determined to right the wrong and set history straight by ridding Earth of her new, cruel masters while receiving a rude awakening lesson on how to survive the future.