The triduum is a three day service that begins on Maundy Thursday and concludes with the Easter Vigil. There are many variations of this service within various Christian traditions - some conclude without a vigil but instead with the sunrise service, for instance - but in general they all look toward the resurrection of Jesus.
Of course, the triduum doesn't last throughout each day. Rather, there are great liturgical pauses on Thursday night and Friday night, where the entirety of the worship is not concluded until the tomb is empty.
This feels weird to many, myself included, probably because we like closure, and these day-long pauses can interrupt our daily lives. How do we live without the completeness of the triduum?
But seriously, the great pauses in the triduum force us to consider the vitality of the resurrection, which of course disrupts our daily existence. Incompleteness and confusion reign without an empty tomb. Though Christ is at work, we await with hope for resurrection, knowing only that we cannot see God, that God seems dead.
And so the triduum gives us the chance to liturgically recognize the disruption of our world wrought by Christ on the cross. We begin Maundy Thursday, and pause after the God of the universe cleans dirty feet. We return Good Friday, and pause after the God of the universe bleeds out for our brokenness. We regather Holy Saturday to vigil, to wait, to hope for resurrection and redemption.
And we find an empty tomb. Excitement and confusion, hope and fear. We would see Jesus, but even then, we must wait.