The Supernova of 1054, Our Very Special Guest Star

The transcript discusses the supernova of 1054, observed as a bright guest star in Taurus. It was visible worldwide and later identified as the Crab Nebula with a central pulsar, M1. The supernova's light took 7,500 years to reach Earth. The Crab Nebula is expanding, and its rate of expansion was found to be accelerating. Theories suggest missing mass due to stellar winds. The supernova remains a subject of fascination and study.

What theories exist regarding the missing mass of the pulsar and nebula from the 1054 supernova?

In what ways has the understanding of the supernova of 1054 evolved over the years?