So I'm a little confused about the Meissner Effect. If we have both a perfect conductor and a superconductor (both above Tc) and place them in a magnetic field and lower their temperatures so they exhibit their respective properties, the magnetic field inside the perfect conductor persists whilst the field inside the superconductor is expelled. Now the perfect conductor is doing what we expect, there is no changing magnetic field and therefore no induced currents to counteract the field inside. Now take the case of the superconductor, it is said that current at the surface are induced and expel the field inside... but how does this happen with no changing magnetic field. Doesn't this violate conservation of energy and Maxwell's equations? Wikipedia and hyperphysics calls this the Meissner effect but there is little to no explanation of what exactly is happening. So what is happening? Is energy conserved because the original internal field is now on the outside? (I'm guessing this is what they mean by "expelled") But how does it expel this field? Thoughts, explanations, am I missing something? Thanks guys!