# Why does time and space have to be relative?

aaaa202
The lorentz-transform shows that both length and time are relative concepts.
My question is: Why does both time and length have to be relative? Why can't you mathematically construct a transform which transforms your x' relative to x such that light has same speed in both the x and x' frame while still keeping time an absolute quantity?

Homework Helper
The lorentz-transform shows that both length and time are relative concepts.
My question is: Why does both time and length have to be relative? Why can't you mathematically construct a transform which transforms your x' relative to x such that light has same speed in both the x and x' frame while still keeping time an absolute quantity?
Measurement of a distance requires simultaneous measurements of two different points in space. The reason distance measurements are not the same in all inertial reference frames (IFORs) is because observers in different IFORs do not agree on what is simultaneous.

AM

harrylin
The lorentz-transform shows that both length and time are relative concepts.
My question is: Why does both time and length have to be relative? Why can't you mathematically construct a transform which transforms your x' relative to x such that light has same speed in both the x and x' frame while still keeping time an absolute quantity?
You can, and it was considered, but that is not sufficient.
We discussed this in the recent (and still open) discussion thread here: