Solar twin stars as a new probe for variations in the ne-structure constant

Our most successful theories of physics contain mysterious, fundamental numbers whose values cannot be calculated, only measured in nature. This thesis describes a new method – the solar twins method – of searching for variation in one such number, the fine-structure constant ("alpha"), which describes the strength of electricity and magnetism. Finding variation in alpha would be a huge discovery, and would immediately point the way towards entire new areas of physics. The solar twins method is found to be accurate and robust, yielding constraints on alpha nearly 100 times more precise than the current best astronomical methods.