Pagina 29 de 212

After further consideration you cast a somewhat disdainful glance

at me-and rightly so-and you declare: "I maintain my previous

definition nevertheless, because in reality it assumes absolutely

nothing about light. There is only one demand to be made of the

definition of simultaneity, namely, that in every real case it

must supply us with an empirical decision as to whether or not

the conception that has to be defined is fulfilled. That my

definition satisfies this demand is indisputable. That light

requires the same time to traverse the path A → M as for the path

B → M is in reality neither a supposition nor a hypothesis about

the physical nature of light, but a stipulation which I can make

of my own freewill in order to arrive at a definition of

simultaneity."