New Propulsion, the "EM Drive"

I'm sorry the EM drive is likely never. At Cern, Switzerland and a few other places we have accelerated a few milligrams per year to 0.999999c. If we can miniturise this process in space we can propel a moderate size space craft for centuries, possibly accelerating the craft as fast a 1 g. Then new problems arise such as most of the systems in the space craft need a major retrofit about twice per century. Also we can't see ahead this fast, so a pea size pebble can total the space craft. Possibly we can use trash not practical to recycle as ejection mass. Possibly we need a few humans aboard to trouble-shoot and make repairs. Food is a problem the second century, if not sooner.

There is nothing other than a photon engine

Besides, to understand the nature of magnetic field do not exactly requires the special relativity even in the classical time space, they can be explained.

I don't think Einstein was wrong with his formula, but he certainly altered the explaination so that some misunderstanding followed up.

The most probably reason for a misleading understanding might be not to let the general people to understand the nature of physics.

However I think the EM drive is therotically impossible. A photon engine is more reliable than this one.