What makes Electricity and Magnetism a unified force?

[denjay]

What makes Electricity and Magnetism a "unified" force?

I'm taking upper level Electromagnetism and we've dealt with the various formulas dealing with electricity and magnetism. It seems to me that we are still largely dealing with them separately. In that, I mean we have a thing called a magnetic field and a thing called an electric field. They are related sure but what exactly makes them a "unified force".

I could be just confused about the semantics of all of this but what makes them a single force?

 

[andrien]

electrostatics and magnetostatics are of course seem unrelated.It is only when one consider the dynamics of electric and magnetic field,one sees the relation.they are best expressed by maxwell eqn.it is treated in every standard book on electromagnetism.

 

[dipole]

Because a magnetic field is just a lorentz transformation of an electric field, and vice versa. This result came later, from special relativity, but all of the electromagnetism can be contained in just a few relativistic equations. They really are the same field, and which you measure is observer dependent.

See http://en.wikipedia.org/wiki/Covariant_formulation_of_classical_electromagnetism for more info.

Normally E&M isn't done this way though, because most people are more comfortable manipulating PDE's than they are dealing with tensor equations.