I'm assuming the book you read was "Starlight and Time" by D. Russell Humphreys, PhD. It's the only book I know of covering the subject.
If you've read the book then you've read pretty much everything accessible written about the subject. There are some more technical math papers associated with it that you can read if your math is up to it. I've only Bachelor level math, so it isn't. But there is really no other information out there other than the book, and some YEC articles summarizing it.
For those of you who haven't read it the essence is a hypothesis is that a combination of General Relativity and a very hypothetical gravitational distribution in the universe allows the Earth and nearby objects like the Sun to be only 6000 years old, thanks to extreme time dilation, while distant stars and the space around them are billons of years old, allowing time for their light to arrive here.
The book enjoyed a brief period of popularity and/or notoriety. The hypothesis is not given credence in mathematical circles or outside the YEC community.