Sentence:  Some of the most beautiful and thus appealing physical theories, including quantum electrodynamics and quantum gravity, have been dogged for decades by infinities that erupt when theorists try to <WSD>prod</WSD> their calculations into new domains. Getting rid of these nagging infinities has probably occupied far more effort than was spent in originating the theories. 
Meaning of the word marked with <WSD> tags:  To encourage, to prompt.