A physics student is currently enrolled in a PhD program in the US, 1.5 years into yet. After few months he will have received his MSc degree and will start working on his thesis. While his physics department is relatively strong, he is unhappy (perhaps even disappointed) because his very sub-field of interest is particularly weak and researchers in this sub-field very rarely publish decent papers.
He's seriously considering starting again from scratch and apply for a new place where people are stronger at his field. Can he apply while still being enrolled in his PhD?
How much negativity does the fact that he plans to drop the current PhD add to his application?
Is it better to apply to UK universities, since in US he will be required to repeat the coursework?