This was a very short story, involving a Scientist who invents a Time Machine. He invites his friend/colleague and family on a trip through time. They both wish to leave their present due to due to either a repressive political regime or due to restrictions placed on research. It is explained that the only reason the Time Machine could be created was by combining data from several different fields of study, and that due to the current climate of specialisation such an event was unlikely to re-occur. The story had an interesting anti-specialisation thread when I read it in the mid 1970-80's.