Interesting short story I read 1970-80s.
A lifepod containing one occupant appears at a museum. At first hairy, dirty and wildly incoherent, the occupant becomes calmer, cleaner and communicative over time. Holding up messages to his window he explains he is travelling slowly backwards in time.
His plan is to build up potential then catapult himself into the future. He's a genius and feels he belongs there. The museum director debates whether to tell him he will be mad when he gets there and what that will mean for the world.
I thought it was called something like either 'Cometh the hour, cometh the man' or 'Uphill slowly, downhill fast'. But can't find either.