I take your meaning, and it seems literally correct word-for-word, but it's hard to know what to make of it: a quantity is constant or it is not, and definitions do not change it.
Perhaps the relevant point is that the speed of light is not a number, but a dimensioned (if that's a word) quantity; and now the question becomes: is the dimensioned quantity (either its numerical value, or the meaning of the units) changing? I agree that it's hard to know how to make sense of the notion of units changing, though.
It's best to separate two elements here -- the measured speed of light, and the relationship between space and time. The relationship between space and time is easily expressed in closed form:
t' = t √(1-v^2/c^2)
That's pretty clear and easy to interpret. So measurements of c may be messy and subject to controversy, but the geometry expressed in the above equation, and what it tells us about spacetime, is much more clear.
Comments
I take your meaning, and it seems literally correct word-for-word, but it's hard to know what to make of it: a quantity is constant or it is not, and definitions do not change it.
Perhaps the relevant point is that the speed of light is not a number, but a dimensioned (if that's a word) quantity; and now the question becomes: is the dimensioned quantity (either its numerical value, or the meaning of the units) changing? I agree that it's hard to know how to make sense of the notion of units changing, though.
It's best to separate two elements here -- the measured speed of light, and the relationship between space and time. The relationship between space and time is easily expressed in closed form:
t' = t √(1-v^2/c^2)
That's pretty clear and easy to interpret. So measurements of c may be messy and subject to controversy, but the geometry expressed in the above equation, and what it tells us about spacetime, is much more clear.