Apologies if this is a really stupid question but I've never seen it satisfactorily explained although that is perhaps because it is a really stupid question! Bill stays on earth, Ted flies off into space travelling randomly at or very near the speed of light. He's back after a few days and discovers hundreds of years have passed on earth. That's fine but what if Ted has a more definite journey - ie. to the nearest star and back. Bill and Ted both know it will take 9 years and Bill has the reception party waiting in 9 years time. But what does Ted actually experience relative to himself - does he find that he gets there in seconds, ie. his instruments indicate he is travelling at many times the speed of light? Or if he still exeriences everything as normal and believes 9 years have passed but actually gets back in just a few seconds having aged 9 years, then surely that is the wrong way round, ie more time has passed for him than on earth?