Does the length of a string depend on it's energy?

[Nickyv2423]

Does the length of a string depend on its energy, or does its energy depend on its length? Similarly, does the area of a d brane depend on its energy, or does its energy depend on its energy?
Are these stupid questions?

 

[haushofer]

Well, if x(y) is a function of y, then y(x) is a function of x, whether you can explicitly write it down or not :P

 

[Urs Schreiber]

Well, if x(y) is a function of y, then y(x) is a function of x,

If the function is single valued, at least (which of course it is in the OP's question). Otherwise one gets a relation, not a function.

 

[haushofer]

That's what I meant by the part you left out.

 

[Urs Schreiber]

That's what I meant by the part you left out.

Okay. To me there is a difference between a function that has no "explicit expression" (say the Gauss error function), and a relation which simply does not map arguments to values at all. But anyway, it's not worth arguing about this much further here.