A strong flux of circularly polarised radiation in a star forming region could bias biological processes to a particular chirality on planets formed around stars in the region. Its an interesting connection, but that s as far as we d want to go right now. The correction within 300 million light years is almost zero. It fits within the model of general relativity, which takes account of time dilation and so on. In A brief history of time , Stephen Hawking talked about string theory.
Strings are a compacted energy source in one dimension.
Strings are now in disfavour. There hasn t been any evidence for them yet.