Einstein proved right; how fat can cause dementia; the science of tornadoes; and mapping English orchards

Summary: Being overweight can raise your chance of dementia according to a new study, but what's the connection?; The tornadoes in the USA last week broke all records - is something going on?; The satellite that has proved (at last) a key part of Einstein's theory of gravity; and the 2000 varieties of apples to be found in Olde English orchards