Susan shakes her head. "Honestly, I don't know. I've been far too buried under my own research. At least that made sense. It was something I could get my head around properly, you know?" She smiled ruefully. "Thanks. It's ... I'm not sure yet how I feel about being here. I was working on this enormous research project -- how to travel between worlds and times, how to stop that kind of thing -- and I thought I had the 'how to travel' bit finished. So I tried, experimentally, for another time on Earth -- and here I am."