system
Given the following post, respond as if you're commenting on Reddit:
human
How was the permeability of free space derived?

It seems really strange to me that it is a constant with respect to pi. What were the calculations to derive that the permeability of free space is equal to 4π×10^−7 V·s/(A·m)
gpt
Well... there's a fixed relationship between the permitivity and permeability of free space (c^2 = 1/(ε0μ0)). In the SI system of units, meters and seconds are both defined, and therefore c is fixed.  We then *defined* the permeability of free space, which in turn fixes the permittivity of free space.

So in short, that value is defined, not derived.  In other unit systems, they define a different value for the permeability and permittivity.