I used to wonder about the Resurrection. What really happened and how could we know? I knew that there were two strands of evidence: empty tomb and appearances. Then I read an article which pointed out that the strands were independent in the earliest literature. (1) Paul mentions only appearances. Mark's Gospel, as originally written, mentions only the tomb. Thus, only the later Evangelists mention both and they received the tomb story only from Mark, not from founders or eye witnesses.
Remembering that Peter's Pentecost Sermon is regarded as an early source, I re-read the Sermon in order to confirm that it mentions only appearances. Instead, I found that it mainly mentions scriptural interpretations. For the first time, I asked: did the disciples infer the Resurrection from scripture? Re-reading Luke's Gospel confirmed this.
First a stranger en route to Emmaus, then the risen Jesus, interpreted scripture. I take the latter to mean that the disciples, inspired by memories of Jesus and by the words of the stranger whom they identified with him, re-interpreted scripture and that Luke later described the meeting in which the disciples formulated their new interpretation as a physical conversation between them and the risen Jesus. I think that this hypothesis adequately addresses the question of what could have happened.
The accounts remain mysterious and evocative. The Jesus who has gone before you to Galilee is a powerful myth like Gautama seeking the way to the end of suffering or Krishna teaching karma yoga on the battlefield of Kurukshetra, except that those guys could have done those things whereas I do not think that Jesus was still around after he had died.
1. John M. G. Barclay, "The Resurrection in Contemporary New Testament Scholarship", Chapter 1 of Gavin D'Costa (Ed.), Resurrection Reconsidered, Oxford, England, 1996, pp. 13-30.