Back In Time

In this article, a scientist has claimed to have discovered a new method for time travel. While I understand little of what is being said, I still have a vague concept of it. And, one thing they should have elaborated on was why one "can't go back in time prior to when the time machine was invented." I don't get that at all.

On a much related note, haven't we all wondered how our lives would be different if we had the option to go back and correct mistakes we made? I can think of any number of things that I wouldn't mind seeing changed. Of course, then one must wonder about the consequences of making said changes...