Not just hard, impossible: https://en.wikipedia.org/wiki/One-way_speed_of_light#Theories_in_which_the_one-way_speed_of_light_is_not_equal_to_the_two-way_speed h

Not just hard, impossible: https://en.wikipedia.org/wiki/One-way_speed_of_light#Theories_in_which_the_one-way_speed_of_light_is_not_equal_to_the_two-way_speed https://en.wikipedia.org/wiki/One-way_speed_of_light#Theorie...